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Jul 2010

Volume 81, Issue 7, Articles (07xxxx)

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back to top Optics; Atoms and Molecules; Spectroscopy; Photon Detectors

Multicomponent wavefield characterization with a novel scanning laser interferometer

Thomas E. Blum, Kasper van Wijk, Bruno Pouet, and Alexis Wartelle

Rev. Sci. Instrum. 81, 073101 (2010); doi:10.1063/1.3455213 (4 pages)

Online Publication Date: 6 July 2010

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The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.
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07.60.Ly Interferometers
42.79.Ls Scanners, image intensifiers, and image converters
91.30.-f Seismology
81.70.Cv Nondestructive testing: ultrasonic testing, photoacoustic testing
43.35.Yb Ultrasonic instrumentation and measurement techniques

Thermoelastic analysis of a silicon surface under x-ray free-electron-laser irradiation

A. R. B. de Castro, Aurea R. Vasconcellos, and Roberto Luzzi

Rev. Sci. Instrum. 81, 073102 (2010); doi:10.1063/1.3455203 (12 pages)

Online Publication Date: 8 July 2010

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We present an analysis of the time evolution of a highly excited silicon substrate after partial absorption of a femtosecond soft x-ray pulse. The detailed time-dependent thermoelastic behavior of the substrate in terms of the displacements u(r,t) is derived for time delays for which the usual local thermodynamic variables, temperature T(r,t) and density n(r,t), become well-defined, namely, a few hundred femtoseconds after x-ray pulse absorption. For practical optical components under present conditions of operation with trains of pulses, we find that in a worst case scenario, already the second pulse in the train could be adversely affected by dynamic thermal distortion induced by the preceding pulse.
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46.25.Hf Thermoelasticity and electromagnetic elasticity (electroelasticity, magnetoelasticity)
42.55.Vc X- and γ-ray lasers
41.60.Cr Free-electron lasers

Stoichiometric analysis of compositionally graded combinatorial amorphous thin film oxides using laser-induced breakdown spectroscopy

N. Edwin Widjonarko, John D. Perkins, Jennifer E. Leisch, Philip A. Parilla, Calvin J. Curtis, David S. Ginley, and Joseph J. Berry

Rev. Sci. Instrum. 81, 073103 (2010); doi:10.1063/1.3455218 (8 pages)

Online Publication Date: 14 July 2010

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Laser-induced breakdown spectroscopy (LIBS) is a recently developed locally destructive elemental analysis technique that can be used to analyze solid, liquid, and gaseous samples. In the system explored here, a neodymium-doped yttrium aluminum garnet laser ablates a small amount of the sample and spectral emission from the plume is analyzed using a set of synchronized spectrometers. We explore the use of LIBS to map the stoichiometry of compositionally graded amorphous indium zinc oxide thin-film libraries. After optimization of the experimental parameters (distance between lens and samples, spot size on the samples, etc.), the LIBS system was calibrated against inductively coupled plasma atomic emission spectroscopy which resulted in a very consistent LIBS-based elemental analysis. Various parameters that need to be watched closely in order to produce consistent results are discussed. We also compare LIBS and x-ray fluorescence as techniques for the compositional mapping of libraries.
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52.38.Mf Laser ablation
42.55.Rz Doped-insulator lasers and other solid state lasers

A simple, compact, and efficient diode-side-pumped linear intracavity frequency doubled Nd:YAG rod laser with 50 ns pulse width and 124 W green output power

Sunil K. Sharma, Pranab K. Mukhopadhyay, Amarjeet Singh, Ranganathan Kandasamy, and Shrikant M. Oak

Rev. Sci. Instrum. 81, 073104 (2010); doi:10.1063/1.3457000 (7 pages)

Online Publication Date: 14 July 2010

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We have developed an efficient and high power repetitively Q-switched diode-pumped intracavity frequency doubled Nd:YAG/LiB3O5 based green laser capable of generating 124 W of average green power with 50 ns pulse duration in a highly compact and robust linear cavity configuration. The pump to green beam conversion efficiency is 16.8% and the overall wall-plug efficiency is 8.3%. The long term power stability is excellent with ±0.4 W variation at the maximum output power and ±2% amplitude fluctuation with ±2.9 ns timing jitter. The M2 parameter of the green beam was measured to be ∼ 27. This, combined with the short pulse duration and the high average power, makes this laser ideal for pumping ultrafast Ti:sapphire laser amplifier systems and for micromachining applications.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Wideband and high-gain frequency stabilization of a 100-W injection-locked Nd:YAG laser for second-generation gravitational wave detectors

Noriaki Ohmae, Shigenori Moriwaki, and Norikatsu Mio

Rev. Sci. Instrum. 81, 073105 (2010); doi:10.1063/1.3458007 (5 pages)

Online Publication Date: 14 July 2010

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Second-generation gravitational wave detectors require a highly stable laser with an output power greater than 100 W to attain their target sensitivity. We have developed a frequency stabilization system for a 100-W injection-locked Nd:YAG (yttrium aluminum garnet) laser. By placing an external wideband electro-optic modulator used as a fast-frequency actuator in the optical path of the slave output, we can circumvent a phase delay in the frequency control loop originating from the pole of an injection-locked slave cavity. Thus, we have developed an electro-optic modulator made of a MgO-doped stoichiometric LiNbO3 crystal. Using this modulator, we achieve a frequency control bandwidth of 800 kHz and a control gain of 180 dB at 1 kHz. These values satisfy the requirement for a laser frequency control loop in second-generation gravitational wave detectors.
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04.80.Nn Gravitational wave detectors and experiments
42.60.By Design of specific laser systems

Short vertical tube furnace for the fabrication of doped glass microsphere lasers

Jonathan M. Ward, Yuqiang Wu (邬宇强), Krimo Khalfi, and Síle Nic Chormaic

Rev. Sci. Instrum. 81, 073106 (2010); doi:10.1063/1.3455198 (4 pages)

Online Publication Date: 15 July 2010

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We report on the design of an electric tube furnace that can be used for the fabrication of doped glass microsphere lasers. The tube furnace has a short hot zone of length 133 mm and is based on a quartz tube design. Doped laser glass particles, specifically Er:Yb phosphate glass (IOG-2), of ∼ 1 μm diameter are blown into the furnace using a 60 ml syringe and microspheres ranging in size from 10 to 400 μm are collected at the output of the tube furnace in a Petri dish. The furnace operates at a wall temperature of ∼ 900 °C and is capable of making microspheres from glasses with glass transition temperatures of at least 375 °C. High quality (Q ∼ 105) whispering gallery modes have been excited within the microspheres by optically pumping at 978 nm via a tapered optical fiber.
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07.20.Hy Furnaces; heaters
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.70.Ce Glasses, quartz
64.70.P- Glass transitions of specific systems

A new tandem mass spectrometer for photofragment spectroscopy of cold, gas-phase molecular ions

Annette Svendsen, Ulrich J. Lorenz, Oleg V. Boyarkin, and Thomas R. Rizzo

Rev. Sci. Instrum. 81, 073107 (2010); doi:10.1063/1.3458014 (7 pages)

Online Publication Date: 20 July 2010

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We present here the design of a new tandem mass spectrometer that combines an electrospray ion source with a cryogenically cooled ion trap for spectroscopic studies of cold, gas-phase ions. The ability to generate large ions in the gas phase without fragmentation, cool them to ∼ 10 K in an ion trap, and perform photofragment spectroscopy opens up new possibilities for spectroscopic characterization of large biomolecular ions. The incorporation of an ion funnel, together with a number of small enhancements, significantly improves the sensitivity, signal stability, and ease of use compared with the previous instrument built in our laboratory.
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07.75.+h Mass spectrometers
33.15.Ta Mass spectra
87.64.-t Spectroscopic and microscopic techniques in biophysics and medical physics
87.15.-v Biomolecules: structure and physical properties

Tunable ultrafast extreme ultraviolet source for time- and angle-resolved photoemission spectroscopy

G. L. Dakovski, Y. Li, T. Durakiewicz, and G. Rodriguez

Rev. Sci. Instrum. 81, 073108 (2010); doi:10.1063/1.3460267 (7 pages)

Online Publication Date: 20 July 2010

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We present a laser-based apparatus suitable for visible pump/extreme UV (XUV) probe time-, energy-, and angle-resolved photoemission spectroscopy utilizing high-harmonic generation from a noble gas. Tunability in a wide range of energies (currently 20–36 eV) is achieved by using a time-delay compensated monochromator, which also preserves the ultrashort duration of the XUV pulses. Using an amplified laser system at 10 kHz repetition rate, approximately 109–1010 photons/s per harmonic are made available for photoelectron spectroscopy. Parallel energy and momentum detection is carried out in a hemispherical electron analyzer coupled with an imaging detector. First applications demonstrate the capabilities of the instrument to easily select the probe wavelength of choice, to obtain angle-resolved photoemission maps (GaAs and URu2Si2), and to trace ultrafast electron dynamics in an optically excited semiconductor (Ge).
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07.81.+a Electron and ion spectrometers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
79.60.Bm Clean metal, semiconductor, and insulator surfaces

A new flexible monochromator setup for quick scanning x-ray absorption spectroscopy

J. Stötzel, D. Lützenkirchen-Hecht, and R. Frahm

Rev. Sci. Instrum. 81, 073109 (2010); doi:10.1063/1.3458015 (7 pages)

Online Publication Date: 21 July 2010

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A new monochromator setup for quick scanning x-ray absorption spectroscopy in the subsecond time regime is presented. Novel driving mechanics allow changing the energy range of the acquired spectra by remote control during data acquisition for the first time, thus dramatically increasing the flexibility and convenience of this method. Completely new experiments are feasible due to the fact that time resolution, edge energy, and energy range of the acquired spectra can be changed continuously within seconds without breaking the vacuum of the monochromator vessel and even without interrupting the measurements. The advanced mechanics are explained in detail and the performance is characterized with x-ray absorption spectra of pure metal foils. The energy scale was determined by a fast and accurate angular encoder system measuring the Bragg angle of the monochromator crystal with subarcsecond resolution. The Bragg angle range covered by the oscillating crystal can currently be changed from 0° to 3.0° within 20 s, while the mechanics are capable to move with frequencies of up to ca. 35 Hz, leading to ca. 14 ms/spectrum time resolution. A new software package allows performing programmed scan sequences, which enable the user to measure stepwise with alternating parameters in predefined time segments. Thus, e.g., switching between edges scanned with the same energy range is possible within one in situ experiment, while also the time resolution can be varied simultaneously. This progress makes the new system extremely user friendly and efficient to use for time resolved x-ray absorption spectroscopy at synchrotron radiation beamlines.
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41.85.Si Particle beam collimators, monochromators
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.

Axicon based conical resonators with high power copper vapor laser

Bijendra Singh, V. V. Subramaniam, S. R. Daultabad, and Ashim Chakraborty

Rev. Sci. Instrum. 81, 073110 (2010); doi:10.1063/1.3457847 (4 pages)

Online Publication Date: 27 July 2010

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We report for the first time the performance of axicon based conical resonators (ABCRs) in a copper vapor laser, with novel results. The unstable conical resonator comprising of conical mirror (reflecting axicon) with axicon angle ∼ π/18, cone angle ∼ 160°, and a convex mirror of 60 cm radius of curvature was effective in reducing the average beam divergence to ∼ 0.15 mrad ( ∼ 25 fold reduction compared to standard multimode plane-plane cavity) with output power of ∼ 31 W. Extraction efficiency of ∼ 50%–60% and beam divergence of <1 mrad was achieved in other stable ABCR configurations using flat and concave mirrors with the axicon. This is a significant improvement compared to 4–5 mrad normally observed in conventional stable resonators in copper vapor lasers. The conical resonators with copper vapor laser provide high misalignment tolerance β ∼ 4–5 mrad where β is the tilt angle of the conical mirror from optimum position responsible for ∼ 20% decline in laser power. The depth of focus d was ∼ three times larger in case of conical resonator as compared to that of standard spherical unstable resonator under similar beam divergence and focusing conditions.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Bh Lenses, prisms and mirrors

Kilohertz dye laser system for high resolution laser spectroscopy

J. H. Gurian, H. Maeda, and T. F. Gallagher

Rev. Sci. Instrum. 81, 073111 (2010); doi:10.1063/1.3462978 (3 pages)

Online Publication Date: 28 July 2010

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We have electro-optically sliced the output light of a commercial Coherent Evolution Nd:YLF laser to pump a kilohertz repetition rate nanosecond dye laser system. Simple and highly adjustable, this laser system can easily be used for initial state preparation for ultrafast systems as well as high resolution spectroscopy.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques

Determining time resolution of microchannel plate detectors for electron time-of-flight spectrometers

Qi Zhang (张琦), Kun Zhao (赵昆), and Zenghu Chang (常增虎)

Rev. Sci. Instrum. 81, 073112 (2010); doi:10.1063/1.3463690 (5 pages)

Online Publication Date: 28 July 2010

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The temporal resolution of a 40 mm diameter chevron microchannel plate (MCP) detector followed by a constant fraction discriminator and a time-to-digital converter was determined by using the third order harmonic of 25 fs Ti:sapphire laser pulses. The resolution was found to deteriorate from 200 to 300 ps as the total voltage applied on the two MCPs increased from 1600 to 2000 V. This was likely due to a partial saturation of the MCP and/or the constant fraction discriminator working with signals beyond its optimum range of pulse width and shape.
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29.30.Aj Charged-particle spectrometers: electric and magnetic
29.30.Ep Charged-particle spectroscopy
07.75.+h Mass spectrometers
42.79.Ls Scanners, image intensifiers, and image converters
back to top Particle Sources, Optics and Acceleration; Particle Detectors

Design and construction of pulsed neutron diagnostic system for plasma focus device (SBUPF1)

Sahar Rajabi Moghadam and Fereydoon Abbasi Davani

Rev. Sci. Instrum. 81, 073301 (2010); doi:10.1063/1.3458010 (4 pages)

Online Publication Date: 12 July 2010

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In this paper, two designs of pulsed neutron counter structure are introduced. To increase the activation counter efficiency, BC-400 plastic scintillator plates along with silver foils are utilized. Rectangular cubic and cylindrical geometries for activation counter cell are modeled using MCNP4C code. Eventually, an optimum length of 14 cm is calculated for the detector cell and optimum numbers of 20 silver foils for rectangular cubic geometry and ten foils for cylindrical geometry have been acquired. Due to the high cost of cutting, polishing of plastics, and etc., the rectangular cubic design is found to be more economical than the other design. In order to examine the functionality and ensure the detector output and corresponding designing, neutron yield of a 2.48 kJ plasma focus device (SBUPF1) in 8 mbar pressure with removal source method for calibration was measured (3.71±0.32)×107 neutrons per shot.
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29.40.Mc Scintillation detectors
42.15.-i Geometrical optics

An open-walled ionization chamber appropriate to tritium monitoring for glovebox

Zhilin Chen, Ruiming Chang, Long Mu, Guoyang Song, Heyi Wang, Guanyin Wu, and Xiye Wei

Rev. Sci. Instrum. 81, 073302 (2010); doi:10.1063/1.3458012 (4 pages)

Online Publication Date: 12 July 2010

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An open-walled ionization chamber is developed to monitor the tritium concentration in gloveboxes in tritium processing systems. Two open walls are used to replace the sealed wall in common ionization chambers, through which the tritium gas can diffuse into the chamber without the aid of pumps and pipelines. Some basic properties of the chamber are examined to evaluate its performance. Results turn out that an open-walled chamber of 1 l in volume shows a considerably flat plateau over 700 V for a range of tritium concentration. The chamber also gives a good linear response to gamma fields over 4 decades under a pressure condition of 1 atm. The pressure dependence characteristics show that the ionization current is only sensitive at low pressures. The pressure influence becomes weaker as the pressure increases mainly due to the decrease in the mean free path of β particles produced by tritium decay. The minimum detection limit of the chamber is 3.7×105 Bq/m3.
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29.40.Cs Gas-filled counters: ionization chambers, proportional, and avalanche counters
23.40.-s β decay; double β decay; electron and muon capture
07.77.Ka Charged-particle beam sources and detectors

Spatially uniform calibration of a liquid xenon detector at low energies using 83mKr

A. Manalaysay, T. Marrodán Undagoitia, A. Askin, L. Baudis, A. Behrens, A. D. Ferella, A. Kish, O. Lebeda, R. Santorelli, D. Vénos, and A. Vollhardt

Rev. Sci. Instrum. 81, 073303 (2010); doi:10.1063/1.3436636 (8 pages)

Online Publication Date: 14 July 2010

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A difficult task with many particle detectors focusing on interactions below ∼ 100 keV is to perform a calibration in the appropriate energy range that adequately probes all regions of the detector. Because detector response can vary greatly in various locations within the device, a spatially uniform calibration is important. We present a new method for calibration of liquid xenon (LXe) detectors, using the short-lived 83mKr. This source has transitions at 9.4 and 32.1 keV, and as a noble gas like Xe, it disperses uniformly in all regions of the detector. Even for low source activities, the existence of the two transitions provides a method of identifying the decays that is free of background. We find that at decreasing energies, the LXe light yield increases, while the amount of electric field quenching is diminished. Additionally, we show that if any long-lived radioactive backgrounds are introduced by this method, they will present less than 67×10−6 events kg−1 day−1 keV−1 in the next generation of LXe dark matter direct detection searches.
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29.40.Mc Scintillation detectors
06.20.fb Standards and calibration

A high resolution, broad energy acceptance spectrometer for laser wakefield acceleration experiments

Christopher M. S. Sears, Sofia Benavides Cuevas, Ulrich Schramm, Karl Schmid, Alexander Buck, Dieter Habs, Ferenc Krausz, and Laszlo Veisz

Rev. Sci. Instrum. 81, 073304 (2010); doi:10.1063/1.3458013 (7 pages)

Online Publication Date: 21 July 2010

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Laser wakefield experiments present a unique challenge in measuring the resulting electron energy properties due to the large energy range of interest, typically several 100 MeV, and the large electron beam divergence and pointing jitter >1 mrad. In many experiments the energy resolution and accuracy are limited by the convolved transverse spot size and pointing jitter of the beam. In this paper we present an electron energy spectrometer consisting of two magnets designed specifically for laser wakefield experiments. In the primary magnet the field is produced by permanent magnets. A second optional electromagnet can be used to obtain better resolution for electron energies above 75 MeV. The spectrometer has an acceptance of 2.5–400 MeV (Emax/Emin>100) with a resolution of better than 1% rms for electron energies above 25 MeV. This high resolution is achieved by refocusing electrons in the energy plane and without any postprocessing image deconvolution. Finally, the spectrometer employs two complimentary detection mechanisms: (1) absolutely calibrated scintillation screens imaged by cameras outside the vacuum chamber and (2) an array of scintillating fibers coupled to a low-noise charge-coupled device.
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29.40.Mc Scintillation detectors
29.20.Ej Linear accelerators
75.50.Ww Permanent magnets

A system for measuring bubble voidage and frequency around tubes immersed in a fluidized bed of particles

Kevin J. Whitty and Michael Siddoway

Rev. Sci. Instrum. 81, 073305 (2010); doi:10.1063/1.3462967 (5 pages)

Online Publication Date: 29 July 2010

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Gas-solid fluidized beds are common in chemical processing and energy production industries. These types of reactors frequently have banks of tubes immersed within the bed to provide heating or cooling, and it is important that the fluid dynamics within these bundles is efficient and uniform. This paper presents a simple, low-cost method for quantitatively analyzing the behavior of gas bubbles within banks of tubes in a fluidized bed cold flow model. Two probes, one containing an infrared emitter and one containing an infrared (IR) detector, are placed into adjacent glass tubes such that the emitter and detector face each other. As bubbles pass through the IR beam, the detector signal increases due to less solid material blocking the path between the emitter and detector. By calibrating the signal response to known voidage of the material, one can measure the bubble voidage at various locations within the tube bundle. The rate and size of bubbles passing through the beam can also be determined by high frequency data collection and subsequent analysis. This technique allows one to develop a map of bubble voidage within a fluidized bed, which can be useful for model validation and system optimization.
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47.55.D- Drops and bubbles
47.60.Dx Flows in ducts and channels
47.55.Lm Fluidized beds
back to top Nuclear Physics, Fusion and Plasmas

A new all-digital time differential γ-γ angular correlation spectrometer

Matthias Nagl, Ulrich Vetter, Michael Uhrmacher, and Hans Hofsäss

Rev. Sci. Instrum. 81, 073501 (2010); doi:10.1063/1.3455186 (9 pages)

Online Publication Date: 14 July 2010

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A new digital time differential perturbed angular correlation spectrometer, designed to measure the energy of and coincidence time between correlated detector signals, here correlated γ photons, is presented. The system overcomes limitations of earlier digital approaches and features improved performance and handling. By consequently separating the data recording and evaluation, it permits the simultaneous measurement of decays with several γ-ray cascades at once and avoids the necessity of premeasurement configuration. Tests showed that the spectrometer reaches a time resolution of 460 ps [using a 60Co sample and Lu1.8Y0.2SiO5:Ce (LYSO) scintillators, otherwise better than 100 ps], an energy resolution that is equivalent to the limit of the used scintillation material, and a processing capability of more than 200 000 γ quanta per detector and second. Other possible applications of the presented methods include nuclear spectroscopy, positron emission tomography, time of flight studies, lidar, and radar.
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29.30.Kv X- and γ-ray spectroscopy
23.20.En Angular distribution and correlation measurements
07.85.Nc X-ray and γ-ray spectrometers
29.40.Mc Scintillation detectors

Tangential soft-x ray imaging for three-dimensional structural studies in a reversed field pinch

T. Onchi, R. Ikezoe, K. Oki, A. Sanpei, H. Himura, and S. Masamune

Rev. Sci. Instrum. 81, 073502 (2010); doi:10.1063/1.3455216 (5 pages)

Online Publication Date: 14 July 2010

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Tangential soft-x ray (SXR) imaging diagnostic has been developed and three-dimensional (3D) structure of the internal magnetic surface has been deduced by comparing the experimental and calculated two-dimensional SXR images in a reversed field pinch. The SXR imaging system, consisting of a MCP, a fluorescent plate, and an intensified charge coupled device camera, has been installed in REversed field pinch of Low-Aspect-ratio eXperiment (RELAX) machine. Major characteristics of an experimental SXR image could be reproduced by numerical calculations of the image using a single island model, suggesting a helical hot core in RELAX. The SXR imaging system could be useful for 3D structural studies when tangential and vertical simultaneous imaging systems would be installed, with appropriate numerical modeling of 3D structure of the magnetic surfaces.
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52.70.La X-ray and γ-ray measurements
52.58.Lq Z-pinches, plasma focus, and other pinch devices
85.60.Ha Photomultipliers; phototubes and photocathodes
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.85.-m X- and γ-ray instruments

High-speed dual Langmuir probe

Robert B. Lobbia and Alec D. Gallimore

Rev. Sci. Instrum. 81, 073503 (2010); doi:10.1063/1.3455201 (9 pages)

Online Publication Date: 15 July 2010

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In an effort to temporally resolve the electron density, electron temperature, and plasma potential for turbulent plasma discharges, a unique high-speed dual Langmuir probe (HDLP) has been developed. A traditional single Langmuir probe of cylindrical geometry (exposed to the plasma) is swept simultaneously with a nearby capacitance and noise compensating null probe (fully insulated from the plasma) to enable bias sweep rates on a microsecond timescale. Traditional thin-sheath Langmuir probe theory is applied for interpretation of the collected probe data. Data at a sweep rate of 100 kHz are presented; however the developed system is capable of running at 1 MHz—near the upper limit of the applied electrostatic Langmuir probe theory for the investigated plasma conditions. Large sets (100 000 sweeps at each of 352 spatial locations) of contiguous turbulent plasma properties are collected using simple electronics for probe bias driving and current measurement attaining 80 dB signal-to-noise measurements with dc to 1 MHz bandwidth. Near- and far-field plume measurements with the HDLP system are performed downstream from a modern Hall effect thruster where the time-averaged plasma properties exhibit the approximate ranges: electron density ne from (1×1015)–(5×1016) m−3, electron temperature Te from 1 to 3.5 eV, and plasma potential Vp from 5 to 15 V. The thruster discharge of 200 V (constant anode potential) and 2 A (average discharge current) displays strong, 2.2 A peak-to-peak, current oscillations at 19 kHz, characteristic of the thruster “breathing mode” ionization instability. Large amplitude discharge current fluctuations are typical for most Hall thrusters, yet the HDLP system reveals the presence of the same 19 kHz fluctuations in ne(t), Te(t), and Vp(t) throughout the entire plume with peak-to-peak divided by mean plasma properties that average 94%. The propagation delays between the discharge current fluctuations and the corresponding plasma density fluctuations agree well with expected ion transit-times observed with distinct plasma waves traveling away from the thruster at velocities >10 km/s.
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52.70.Ds Electric and magnetic measurements
52.80.-s Electric discharges
52.35.Ra Plasma turbulence
52.25.Jm Ionization of plasmas
52.25.Gj Fluctuation and chaos phenomena
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)

A novel flat-response x-ray detector in the photon energy range of 0.1–4 keV

Zhichao Li, Xiaohua Jiang, Shenye Liu, Tianxuan Huang, Jian Zheng, Jiamin Yang, Sanwei Li, Liang Guo, Xuefeng Zhao, Huabin Du, Tianming Song, Rongqing Yi, Yonggang Liu, Shaoen Jiang, and Yongkun Ding

Rev. Sci. Instrum. 81, 073504 (2010); doi:10.1063/1.3460269 (4 pages)

Online Publication Date: 19 July 2010

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A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1–4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1–4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiation temperatures inferred from the detector agree well with those from the diagnostic instrument Dante installed at the same azimuth angle from the hohlraum axis, demonstrating the feasibility of the detector.
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29.40.-n Radiation detectors

A uniformly redundant imaging array of penumbral apertures coupled with a heuristic reconstruction for hard x-ray and neutron imaging

Tatsuki Ueda, Shinsuke Fujioka, Shinya Nozaki, Rumiko Azuma, Yen-Wei Chen, and Hiroaki Nishimura

Rev. Sci. Instrum. 81, 073505 (2010); doi:10.1063/1.3460623 (5 pages)

Online Publication Date: 19 July 2010

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A coded imaging and decoding (image reconstruction) scheme was developed for diagnosing a hot and dense region emitting hard x-rays and neutrons in laser-fusion plasmas. Because the imager was a uniformly redundant array of penumbral aperture (URPA) arranged in an M-matrix, URPA leads to N times (N: the total number of apertures) enhancement of signal intensity in comparison with a single penumbral aperture. A recorded penumbral image was reconstructed by a computer-based heuristic method to reduce artifacts caused by noises contained in a penumbral image. Applicability of this technique was investigated by imaging x-rays emitted from laser-produced plasmas, demonstrating a spatial resolution of 16 μm. Under the present conditions, the spatial resolution was determined dominantly by a detector resolution (10.5 μm) and a signal-to-noise ratio of the obtained penumbral image.
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52.70.La X-ray and γ-ray measurements
52.58.-c Other confinement methods
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.25.Tx Emission, absorption, and scattering of particles
42.30.Wb Image reconstruction; tomography
52.70.Nc Particle measurements

Electron cyclotron emission reconstruction image and m/n = 3/2 mode in HT-7 tokamak

Erzhong Li, Liqun Hu, Bili Ling, Yong Liu, Ang Ti, Kaiyun Chen, Biao Shen, and Xiang Gao

Rev. Sci. Instrum. 81, 073506 (2010); doi:10.1063/1.3459882 (4 pages)

Online Publication Date: 21 July 2010

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Electron cyclotron emission reconstruction image has been used for flux surface reconstruction. The reconstruction image is based on plasma rigid rotation which is obtained from Mirnov diagnostic. From the reconstructed two-dimensional flux surface, the classical m/n = 3/2 mode is visualized, which is of similar spatial structure as neoclassical 3/2 mode observed in some other tokamaks [ B. Esposito et al., Phys. Rev. Lett. 100, 045006 (2008) ].
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52.70.-m Plasma diagnostic techniques and instrumentation
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.35.Vd Magnetic reconnection
52.55.Fa Tokamaks, spherical tokamaks
52.65.Kj Magnetohydrodynamic and fluid equation

The MaPLE device of Saha Institute of Nuclear Physics: Construction and its plasma aspects

Rabindranath Pal, Subir Biswas, Subhasis Basu, Monobir Chattopadhyay, Debjyoti Basu, and Manis Chaudhuri

Rev. Sci. Instrum. 81, 073507 (2010); doi:10.1063/1.3458005 (6 pages)

Online Publication Date: 21 July 2010

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See Also: Publisher's Note

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The Magnetized Plasma Linear Experimental (MaPLE) device is a low cost laboratory plasma device at Saha Institute of Nuclear Physics fabricated in-house with the primary aim of studying basic plasma physics phenomena such as plasma instabilities, wave propagation, and their nonlinear behavior in magnetized plasma regime in a controlled manner. The machine is specially designed to be a versatile laboratory device that can provide a number of magnetic and electric scenario to facilitate such studies. A total of 36 number of 20-turn magnet coils, designed such as to allow easy handling, is capable of producing a uniform, dc magnetic field of about 0.35 T inside the plasma chamber of diameter 0.30 m. Support structure of the coils is planned in an innovative way facilitating straightforward fabrication and easy positioning of the coils. Further special feature lies in the arrangement of the spacers between the coils that can be maneuvered rather easily to create different magnetic configurations. Various methods of plasma production can be suitably utilized according to the experimental needs at either end of the vacuum vessel. In the present paper, characteristics of a steady state plasma generated by electron cyclotron resonance method using 2.45 GHz microwave power are presented. Scans using simple probe drives revealed that a uniform and long plasma column having electron density ∼ 3–5×1010 cm−3 and temperature ∼ 7–10 eV, is formed in the center of the plasma chamber which is suitable for wave launching experiments.
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52.75.-d Plasma devices
52.50.-b Plasma production and heating
52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma
52.25.-b Plasma properties
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)

Quantum-dot-array diffraction grating with single order diffraction property for soft x-ray region

Longyu Kuang, Chuanke Wang, Zhebin Wang, Leifeng Cao, Xiaoli Zhu, Changqing Xie, Shenye Liu, and Yongkun Ding

Rev. Sci. Instrum. 81, 073508 (2010); doi:10.1063/1.3464197 (4 pages)

Online Publication Date: 22 July 2010

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A gold transmission grating is used routinely to disperse the x-ray spectrum at the Z soft x-ray facility to measure the spectrum and temporal history of the absolute soft x-ray power emitted from z-pinch and hohlraum radiation sources. A quantum-dot-array diffraction grating (QDADG) of 250 lines/mm for soft x-ray is designed and fabricated for the first time according to the principle of binary sinusoidal transmission grating. The diffraction efficiencies of the grating are measured in the 150–300 eV photon energy range on the Beamline 3W1B of Beijing Synchrotron Radiation Facility. This article describes the basic concept and calibration techniques and presents calibration results. It is shown that the 250 lines/mm QDADG can be used to disperse light without higher-order diffractions in soft x-ray range, and the diffraction efficiencies of this grating are nearly constant (about 25%), which is beneficial in the spectrum analysis.
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42.79.Dj Gratings
41.50.+h X-ray beams and x-ray optics

A new absolute extreme ultraviolet image system designed for studying the radiated power of the Joint Texas Experimental Tokamak discharges

J. Zhang, G. Zhuang, Z. J. Wang, Y. H. Ding, X. Q. Zhang, and Y. J. Tang

Rev. Sci. Instrum. 81, 073509 (2010); doi:10.1063/1.3469799 (5 pages)

Online Publication Date: 29 July 2010

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A bolometer imaging system mounted on different toroidal and poloidal locations used for radiation observation has been developed in the Joint Texas Experimental Tokamak (J-TEXT tokamak). Three miniature pinhole AXUV16ELG (16 elements absolute extreme ultraviolet silicon photodiodes) array cameras, which are settled down in the same toroidal position but in three different poloidal places, can provide a broad viewing angle that covers the whole plasma cross-section, and hence can measure the total radiated power and provide the radiated emissive profile, while nine AXUV10EL (10 elements absolute extreme ultraviolet silicon photodiodes) array cameras are divided into three groups and will be mounted on different toroidal locations to observe the toroidal radiated power distribution. Among these detectors, one element of the AXUV16ELG array is absolutely calibrated by the synchrotron radiation source to verify the system reliability. Although there are some discrepancies between the typical responsivity given by IRD Co. and the calibrated results, it is confirmed that the discrepancies have no major effect on the final result after the simulation. The details of the system as well as observations are presented in the paper.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.55.Fa Tokamaks, spherical tokamaks
52.80.-s Electric discharges
06.20.fb Standards and calibration
back to top Microscopy and Imaging

Thermal exchange radius measurement: Application to nanowire thermal imaging

Etienne Puyoo, Stéphane Grauby, Jean-Michel Rampnoux, Emmanuelle Rouvière, and Stefan Dilhaire

Rev. Sci. Instrum. 81, 073701 (2010); doi:10.1063/1.3455214 (5 pages)

Online Publication Date: 2 July 2010

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In scanning thermal microscopy (SThM) techniques, the thermal exchange radius between tip and sample is a crucial parameter. Indeed, it limits the lateral spatial resolution but, in addition, an accurate value of this parameter is necessary for a precise identification of thermal properties. But until now, the thermal exchange radius is usually estimated but not measured. This paper presents an experimental procedure, based on the 3ω-SThM method, to measure its value. We apply this procedure to evaluate the thermal exchange radius of two commercial probes: the well-known Wollaston one and a new probe constituted of a palladium film on a SiO2 substrate. Finally, presenting silicon nanowire images, we clearly demonstrate that this new probe can reach a spatial resolution better than 100 nm whereas the Wollaston probe hardly reaches a submicronic spatial resolution.
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07.20.-n Thermal instruments and apparatus
07.79.-v Scanning probe microscopes and components
81.07.Gf Nanowires

A simple hard x-ray “nanoslit” for measuring wavefront intensity

Hidekazu Takano, Takuto Hashimoto, Takuya Tsuji, Takahisa Koyama, Yoshiyuki Tsusaka, and Yasushi Kagoshima

Rev. Sci. Instrum. 81, 073702 (2010); doi:10.1063/1.3456447 (3 pages)

Online Publication Date: 12 July 2010

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A new method is proposed for nanoscale hard x-ray measurements. This method uses a reflection on a heavy-metal wire that functions as a single slit with a nanoscale aperture for a parallel x-ray beam. This “nanoslit” can be used to perform high-spatial-resolution measurements of the intensity distribution of a wavefront that diverges from an aperture. In experiments, Fresnel fringes generated by a rectangular aperture were measured using a 300-μm-diameter platinum wire as the nanoslit. In these experiments, the finest fringes with a period of 26 nm could be successfully resolved.
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07.85.-m X- and γ-ray instruments

Quality analysis of selective microparticle deposition on electrically programmable surfaces

J. Wagner, F. Löffler, K. König, S. Fernandez, A. Nesterov-Müller, F. Breitling, F. R. Bischoff, V. Stadler, M. Hausmann, and V. Lindenstruth

Rev. Sci. Instrum. 81, 073703 (2010); doi:10.1063/1.3456986 (6 pages)

Online Publication Date: 12 July 2010

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Image processing and pattern analysis can evaluate the deposition quality of triboelectrically charged microparticles on charged surfaces. The image processing method presented in this paper aims at controlling the quality of peptide arrays generated by particle based solid phase Merrifield combinatorial peptide synthesis. Incorrectly deposited particles are detected before the amino acids therein are coupled to the growing peptide. The calibration of the image acquisition is performed in a supervised training step in which all parameters of the quality analyzing algorithm are learnt given one representative image. Then, the correct deposition pattern is determined by a linear support vector machine. Knowing the pattern, contaminated areas can be detected by comparing the pattern with the actual deposition. Taking into account the resolution of the image acquisition system and its magnification factor, the number and size of contaminating particles can be calculated out of the number of connected foreground pixels.
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87.80.-y Biophysical techniques (research methods)

Digitally tunable, wide-band amplitude, phase, and frequency detection for atomic-resolution scanning force microscopy

Z. Khan, C. Leung, B. A. Tahir, and B. W. Hoogenboom

Rev. Sci. Instrum. 81, 073704 (2010); doi:10.1063/1.3458009 (5 pages)

Online Publication Date: 14 July 2010

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Frequency-modulation atomic force microscopy (FM-AFM) relies on an accurate tracking of the resonance frequency of a scanning probe. It is now used in environments ranging from ultrahigh vacuum to aqueous solutions, for slow and for fast imaging, with probes resonating from a few kilohertz up to several megahertz. Here we present a versatile experimental setup that detects amplitude, phase, and frequency of AFM probes for resonance frequencies up to 15 MHz and with >70 kHz maximum bandwidth for amplitude/phase detection. We provide generic parameter settings for variable-bandwidth frequency detection and test these using our setup. The signal-to-noise ratio of the frequency detector is sufficiently high to record atomic-resolution images of mica by FM-AFM in aqueous solution.
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42.60.Fc Modulation, tuning, and mode locking
07.79.Lh Atomic force microscopes

Self-manifestation and universal correction of image distortion in scanning tunneling microscopy with spiral scan

Junting Wang, Jihui Wang, Yubin Hou, and Qingyou Lu

Rev. Sci. Instrum. 81, 073705 (2010); doi:10.1063/1.3449322 (5 pages)

Online Publication Date: 15 July 2010

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We demonstrate that severe distortions may occur but hard to identify in a standard line-by-line scanned scanning tunneling microscope image, deforming the atomic lattice into a completely different structure type and leading to a wrong interpretation of the data. We also show that a spiral scan image can reveal the details of the drifting by causing the atomic rows to bend with the curvatures being closely related to the extent and direction of the drifting. By straightening the curved atomic rows, the true atomic arrangement can thus be precisely recovered.
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07.79.Cz Scanning tunneling microscopes

Multiple-scanning-probe tunneling microscope with nanoscale positional recognition function

Seiji Higuchi, Hiromi Kuramochi, Olivier Laurent, Takashi Komatsubara, Shinichi Machida, Masakazu Aono, Kenichi Obori, and Tomonobu Nakayama

Rev. Sci. Instrum. 81, 073706 (2010); doi:10.1063/1.3456990 (5 pages)

Online Publication Date: 15 July 2010

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Over the past decade, multiple-scanning-probe microscope systems with independently controlled probes have been developed for nanoscale electrical measurements. We developed a quadruple-scanning-probe tunneling microscope (QSPTM) that can determine and control the probe position through scanning-probe imaging. The difficulty of operating multiple probes with submicrometer precision drastically increases with the number of probes. To solve problems such as determining the relative positions of the probes and avoiding of contact between the probes, we adopted sample-scanning methods to obtain four images simultaneously and developed an original control system for QSPTM operation with a function of automatic positional recognition. These improvements make the QSPTM a more practical and useful instrument since four images can now be reliably produced, and consequently the positioning of the four probes becomes easier owing to the reduced chance of accidental contact between the probes.
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07.79.Cz Scanning tunneling microscopes
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)

Intermittent contact hydration scanning probe microscopy

G. Aloisi, F. Bacci, M. Carlà, and D. Dolci

Rev. Sci. Instrum. 81, 073707 (2010); doi:10.1063/1.3458006 (4 pages)

Online Publication Date: 22 July 2010

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Hydration scanning probe microscopy is a technique similar to scanning tunneling microscopy, in which the probe current, sustained by the slight surface conduction of a thin hydration layer covering an insulating support surface, is essentially electrochemical in nature instead of electronic tunneling. Such a technique allows the imaging of a great variety of samples, including insulators, provided that they are hydrophilic, as well as the study of molecular samples of biological interest (such as DNA) fixed on a suitable supporting surface. The main problem to obtain stable and reproducible images comes from the very critical determination of the operating conditions under which the probe-hydration layer interaction does not lead to the formation of a relatively large water meniscus. It has been suggested that this issue can be removed by adding a high frequency oscillation to the probe movement, as in tapping atomic force microscopy. Meniscus formation and breakup have been investigated in order to determine the best values for the amplitude and the frequency of the oscillation. Results obtained in this mode are discussed in comparison with the usual continuous contact mode.
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07.79.-v Scanning probe microscopes and components

Real-time optical system for observing crystallization in levitated silicate melt droplets

Yuko Inatomi, Atul Srivastava, Hisao Satoh, Takao Maki, and Katsuo Tsukamoto

Rev. Sci. Instrum. 81, 073708 (2010); doi:10.1063/1.3462968 (5 pages)

Online Publication Date: 22 July 2010

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In this study, a real-time optical system was developed to observe crystallization in a small spherical melt droplet (few millimeters in diameter) by containerless processing. This system can be used to simultaneously observe the inside and the surface of a transparent melt droplet, as well as its ambient gas atmosphere at high temperatures. A silicate melt with a diameter of ∼ 2 mm and a composition of MgO:SiO2 = 48:52 was levitated using a gas-jet levitation system, and its crystallization process was successfully observed from 2385 K in real time with good contrast using the developed optical setup.
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64.70.dg Crystallization of specific substances
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Noise analysis of grating-based x-ray differential phase contrast imaging

Vincent Revol, Christian Kottler, Rolf Kaufmann, Ulrich Straumann, and Claus Urban

Rev. Sci. Instrum. 81, 073709 (2010); doi:10.1063/1.3465334 (7 pages)

Online Publication Date: 27 July 2010

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The sensitivity of x-ray radiographic images, meaning the minimal detectable change in the thickness or in the index of refraction of a sample, is directly related to the uncertainty of the measurement method. In the following work, we report on the recent development of quantitative descriptions for the stochastic error of grating-based differential phase contrast imaging (DPCi). Our model includes the noise transfer characteristics of the x-ray detector and the jitter of the phase steps. We find that the noise in DPCi depends strongly on the phase stepping visibility and the sample properties. The results are supported by experimental evidence acquired with our new instrument with a field of view of 50×70 mm2. Our conclusions provide general guidelines to optimize grating interferometers for specific applications and problems.
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07.85.-m X- and γ-ray instruments

Fabrication of multilayer Laue lenses by a combination of pulsed laser deposition and focused ion beam

Tobias Liese, Volker Radisch, and Hans-Ulrich Krebs

Rev. Sci. Instrum. 81, 073710 (2010); doi:10.1063/1.3462985 (4 pages)

Online Publication Date: 27 July 2010

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X-ray diffractive techniques using Fresnel zone plate lenses of various forms are of great technical interest because of their ability to form images at very high spatial resolution, but the zone plates are unfortunately very hard to produce by lithography. Alternatively, multilayer Laue lenses (MLLs) and multilayer zone plates are used due to the higher and easily adjustable aspect ratio necessary for different wavelengths. In this paper, the fabrication of a MLL by a combination of pulsed laser deposition and focused ion beam machining is described. All steps of the production of a Ti/ZrO2 microlens test structure with focal length of 220 μm (for a wavelength of 2.88 nm in the “water window” regime) are explained in detail. It is shown that this combination of two powerful techniques is very effective for the fabrication of MLL. All steps can be done in a very precise and controlled way without introducing damage to the grown multilayer structures.
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42.79.Bh Lenses, prisms and mirrors
42.82.Cr Fabrication techniques; lithography, pattern transfer
81.15.Fg Pulsed laser ablation deposition

An alternative method to determining optical lever sensitivity in atomic force microscopy without tip-sample contact

Christopher J. Tourek and Sriram Sundararajan

Rev. Sci. Instrum. 81, 073711 (2010); doi:10.1063/1.3459886 (5 pages)

Online Publication Date: 28 July 2010

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Force studies using atomic force microscopy generally require knowledge of the cantilever spring constants and the optical lever sensitivity. The traditional method of evaluating the optical lever sensitivity by pressing the tip against a hard surface can damage the tip, especially sharp ones. Here a method is shown to calculate the sensitivity without having to bring the tip into contact. Instead a sharpened tungsten wire is used to cause a point contact directly onto the cantilever and cause cantilever bending. Using beam theory, the sensitivity thus found can be converted to the equivalent sensitivity that would be obtained using the tip location. A comparison is presented between sensitivity values obtained from the conventional tip contact method and those derived from the wire-based technique for a range of cantilevers in air. It was found that the difference between the calculated sensitivity from the wire-based technique and the sensitivity obtained conventionally was less than 12%. These measurements indicate the presented method offers a simple alternative approach to obtain optical lever sensitivity without compromising the tip shape.
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07.79.Lh Atomic force microscopes
back to top Condensed Matter; Materials

Hot nanoindentation in inert environments

Jonathan C. Trenkle, Corinne E. Packard, and Christopher A. Schuh

Rev. Sci. Instrum. 81, 073901 (2010); doi:10.1063/1.3436633 (13 pages)

Online Publication Date: 1 July 2010

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An instrument capable of performing nanoindentation at temperatures up to 500 °C in inert atmospheres, including partial vacuum and gas near atmospheric pressures, is described. Technical issues associated with the technique (such as drift and noise) and the instrument (such as tip erosion and radiative heating of the transducer) are identified and addressed. Based on these considerations, preferred operation conditions are identified for testing on various materials. As a proof-of-concept demonstration, the hardness and elastic modulus of three materials are measured: fused silica (nonoxidizing), aluminum, and copper (both oxidizing). In all cases, the properties match reasonably well with published data acquired by more conventional test methods.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli

Wide-range wavevector selectivity of magnon gases in Brillouin light scattering spectroscopy

C. W. Sandweg, M. B. Jungfleisch, V. I. Vasyuchka, A. A. Serga, P. Clausen, H. Schultheiss, B. Hillebrands, A. Kreisel, and P. Kopietz

Rev. Sci. Instrum. 81, 073902 (2010); doi:10.1063/1.3454918 (4 pages)

Online Publication Date: 6 July 2010

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Brillouin light scattering spectroscopy is a powerful technique for the study of fast magnetization dynamics with both frequency and wavevector resolutions. Here, we report on a distinct improvement of this spectroscopic technique toward two-dimensional wide-range wavevector selectivity in a backward scattering geometry. Spin-wave wavevectors oriented perpendicularly to the bias magnetic field are investigated by tilting the sample within the magnet gap. Wavevectors which are oriented parallel to the applied magnetic field are analyzed by turning the entire setup, including the magnet system. The setup features a wide selectivity of wavevectors up to 2.04×105 rad/cm for both orientations, and allows selecting and measuring wavevectors of dipole- and exchange-dominated spin waves of any orientation to the magnetization simultaneously.
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07.60.Rd Visible and ultraviolet spectrometers
75.30.Ds Spin waves
75.78.-n Magnetization dynamics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Simplified manual fabrication of cubic-zirconia gem anvils for extended energy-range spectroscopic studies to routine high pressures of 100–150 kbar (10–15 GPa)

N. R. Jackson, R. M. Erasmus, and G. R. Hearne

Rev. Sci. Instrum. 81, 073903 (2010); doi:10.1063/1.3455812 (6 pages)

Online Publication Date: 7 July 2010

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Methodology has been developed so as to attain routine extreme conditions as high as 10–15 GPa in a gem anvil optical pressure cell using hand (manual) processed gem anvils. The anvils polished by a simplified hand held tool are inexpensive single crystal cubic zirconia (CZ) gems that have various optical advantages over diamond anvils. Appreciable pressures are attained with culet and corresponding sample cavity dimensions that are relatively convenient to load with sample material. Some technical details are provided as regards the simplified manual fabrication process, thus emphasizing the relative ease and cost effectiveness of the hand polishing technique for fabricating such high pressure anvils. Raman spectroscopy measurements, in triple subtractive mode with a confocal pinhole geometry, are used to exemplify the usefulness of the CZ gem anvil cell methodology in pressure tuning experiments. This is particularly convenient for conventional low wave-number (lattice mode regime) Raman high pressure studies, which have not been reported previously in this context. Various other applications of such anvils are suggested.
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81.05.-t Specific materials: fabrication, treatment, testing, and analysis
78.30.Hv Other nonmetallic inorganics
62.65.+k Acoustical properties of solids

RASOR: An advanced instrument for soft x-ray reflectivity and diffraction

T. A. W. Beale, T. P. A. Hase, T. Iida, K. Endo, P. Steadman, A. R. Marshall, S. S. Dhesi, G. van der Laan, and P. D. Hatton

Rev. Sci. Instrum. 81, 073904 (2010); doi:10.1063/1.3458004 (9 pages)

Online Publication Date: 12 July 2010

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We report the design and construction of a novel soft x-ray diffractometer installed at Diamond Light Source. The beamline endstation RASOR is constructed for general users and designed primarily for the study of single crystal diffraction and thin film reflectivity. The instrument is comprised of a limited three circle (θ, 2θ, and χ) diffractometer with an additional removable rotation (ϕ) stage. It is equipped with a liquid helium cryostat, and post-scatter polarization analysis. Motorized motions are provided for the precise positioning of the sample onto the diffractometer center of rotation, and for positioning the center of rotation onto the x-ray beam. The functions of the instrument have been tested at Diamond Light Source, and initial test measurements are provided, demonstrating the potential of the instrument.
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61.05.cm X-ray reflectometry (surfaces, interfaces, films)
61.05.C- X-ray diffraction and scattering

Turnbuckle diamond anvil cell for high-pressure measurements in a superconducting quantum interference device magnetometer

Gaétan Giriat, Weiwei Wang, J. Paul Attfield, Andrew D. Huxley, and Konstantin V. Kamenev

Rev. Sci. Instrum. 81, 073905 (2010); doi:10.1063/1.3465311 (5 pages)

Online Publication Date: 27 July 2010

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We have developed a miniature diamond anvil cell for magnetization measurements in a widely used magnetic property measurement system commercial magnetometer built around a superconducting quantum interference device. The design of the pressure cell is based on the turnbuckle principle in which force can be created and maintained by rotating the body of the device while restricting the counterthreaded end-nuts to translational movement. The load on the opposed diamond anvils and the sample between them is generated using a hydraulic press. The load is then locked by rotating the body of the cell with respect to the end-nuts. The dimensions of the pressure cell have been optimized by use of finite element analysis. The cell is approximately a cylinder 7 mm long and 7 mm in diameter and weighs only 1.5 g. Due to its small size the cell thermalizes rapidly. It is capable of achieving pressures in excess of 10 GPa while allowing measurements to be performed with the maximum sensitivity of the magnetometer. The performance of the pressure cell is illustrated by a high pressure magnetic study of Mn3[Cr(CN)6]2⋅xH2O Prussian blue analog up to 10.3 GPa.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)

Deconvolution of charged particle spectra from neutron depth profiling using Simplex method

V. Hnatowicz, J. Vacík, and D. Fink

Rev. Sci. Instrum. 81, 073906 (2010); doi:10.1063/1.3463692 (7 pages)

Online Publication Date: 28 July 2010

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Neutron depth profiling (NDP), based on neutron induced nuclear reactions, is a well known, nondestructive technique for the determination of the concentration depth profiles of some isotopes in the surface layers of solids. The profile determination consists of deconvolution of a relevant part of the energy spectra of the charged reaction products. Several solutions have been suggested for this problem. In this work, an alternative computer code (LIBOR), which makes use of the Simplex minimization technique for the deconvolution of the NDP spectra, is described and its performance is documented on several examples.
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61.72.sh Impurity distribution
back to top Chemistry

Electrochemical cell for neutron reflectometry studies of the structure of ionic liquids at electrified interface

Y. Lauw, T. Rodopoulos, M. Gross, A. Nelson, R. Gardner, and M. D. Horne

Rev. Sci. Instrum. 81, 074101 (2010); doi:10.1063/1.3455178 (6 pages)

Online Publication Date: 28 July 2010

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We describe the design and use of a closed three-electrode electrochemical cell for neutron reflectometry studies of the structure of the electrical double-layer in ionic liquids. A transparent glass counter electrode was incorporated to allow easy monitoring of any gas bubbles trapped in the cell. A 100 mm diameter silicon wafer polished to 0.1 nm rms roughness coated with gold over a chromium adhesion layer was used as the working electrode. The utility of the cell was demonstrated during neutron reflectometry measurements of the ultrahigh purity ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyr][NTf2]) at two different applied potentials.
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61.05.fj Neutron reflectometry
61.25.Em Molecular liquids
82.45.Fk Electrodes
82.45.Wx Polymers and organic materials in electrochemistry
back to top Biology and Medicine

Experimental study of pancreaticojejunostomy completed using anastomotic chains

Wei-Dong Pan, Rui-Yun Xu, Nan Li, He-Ping Fang, Cu-Zhi Pan, and Zhao-Feng Tang

Rev. Sci. Instrum. 81, 074301 (2010); doi:10.1063/1.3458008 (5 pages)

Online Publication Date: 15 July 2010

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The most difficult, time-consuming, and complication-prone step in pancreaticoduodenectomy is the pancreaticojejunostomy step. The largest disadvantage of this kind of anastomosis is the high incidence of postoperative anastomotic leakage. Once pancreatic leakage occurs, the patient death rate can be very high. The aim of this study was to design a pancreaticojejunostomy procedure using anastomotic chains, which results in the cut end of the jejunum being attached to the pancreatic stump without suturing, and to evaluate the safety and efficacy of this procedure in domestic pigs. The pancreaticojejunal anastomotic chains had the following structures: the chains consisted of two braceletlike chains made of titanium, named chain A and chain B. The function of chain A was to attach the free jejunal end onto the pancreatic stump, whereas the function of chain B was to tighten the contact between the jejunal wall and the surface of the pancreatic stump to eliminate gaps between the two structures and ensure tightness that is sufficient to guarantee that there is no leakage of jejunal fluid or pancreatic juice. The following procedure was used to assess the safety and efficacy of the procedure: pancreaticojejunostomies were performed on ten domestic pigs using anastomotic chains. The time required to complete the pancreaticojejunal anastomoses, the pressure tolerance of the pancreaticojejunal anastomoses, the pig death rate, and the histopathological examinations of the pancreaticojejunostomy tissues were recorded. The average time required to complete the pancreaticojejunal anastomosis procedure was 13±2 min. The observed tolerance pressure of the pancreaticojejunal anastomoses was more than 90 mm H2O. All ten domestic pigs that underwent operations were still alive four weeks after the operations. Pathological examinations showed that the anastomotic surfaces were completely healed, and the pancreatic cutting surfaces were primarily epithelialized. In conclusion, the use of anastomotic chains in pancreaticojejunostomy procedures results in a decrease in or elimination of pancreatic leakage. In addition, the procedure is simple to perform, is not time-intensive, and appears to be safe in a pig model.
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87.85.-d Biomedical engineering

Development of a multitarget tracking system for paramecia

Yu-Sing Yeh, Ke-Nung Huang, Sun-Lon Jen, Yan-Chay Li, and Ming-Shing Young

Rev. Sci. Instrum. 81, 074302 (2010); doi:10.1063/1.3460266 (8 pages)

Online Publication Date: 21 July 2010

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This investigation develops a multitarget tracking system for the motile protozoa, paramecium. The system can recognize, track, and record the orbit of swimming paramecia within a 4 mm diameter of a circular experimental pool. The proposed system is implemented using an optical microscope, a charge-coupled device camera, and a software tool, Laboratory Virtual Instrumentation Engineering Workbench (LABVIEW). An algorithm for processing the images and analyzing the traces of the paramecia is developed in LABVIEW. It focuses on extracting meaningful data in an experiment and recording them to elucidate the behavior of paramecia. The algorithm can also continue to track paramecia even if they are transposed or collide with each other. The experiment demonstrates that this multitarget tracking design can really track more than five paramecia and simultaneously yield meaningful data from the moving paramecia at a maximum speed of 1.7 mm/s.
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87.17.Jj Cell locomotion, chemotaxis
89.20.Ff Computer science and technology

Magnet polepiece design for uniform magnetic force on superparamagnetic beads

Todd Fallesen, David B. Hill, Matthew Steen, Jed C. Macosko, Keith Bonin, and George Holzwarth

Rev. Sci. Instrum. 81, 074303 (2010); doi:10.1063/1.3469792 (5 pages)

Online Publication Date: 29 July 2010

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Here we report construction of a simple electromagnet with novel polepieces which apply a spatially uniform force to superparamagnetic beads in an optical microscope. The wedge-shaped gap was designed to keep ∂Bx/∂y constant and B large enough to saturate the bead. We achieved fields of 300–600 mT and constant gradients of 67 T/m over a sample space of 0.5×4 mm2 in the focal plane of the microscope and 0.05 mm along the microscope optic axis. Within this space the maximum force on a 2.8 μm diameter Dynabead was 12 pN with a spatial variation of approximately 10%. Use of the magnet in a biophysical experiment is illustrated by showing that gliding microtubules propelled by the molecular motor kinesin can be stopped by the force of an attached magnetic bead.
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07.55.Db Generation of magnetic fields; magnets
75.20.-g Diamagnetism, paramagnetism, and superparamagnetism
back to top Gravity; Geophysics; Astronomy and Astrophysics

Quartz tube extensometer for observation of Earth tides and local tectonic deformations at the Sopronbánfalva Geodynamic Observatory, Hungary

Gy. Mentes

Rev. Sci. Instrum. 81, 074501 (2010); doi:10.1063/1.3470100 (6 pages)

Online Publication Date: 29 July 2010

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In May 1990, a quartz tube extensometer was installed in the Sopronbánfalva Geodynamic Observatory of the Geodetic and Geophysical Research Institute (GGRI) of the Hungarian Academy of Sciences for recording Earth tides and recent tectonic movements. The paper describes the construction of the extensometer and a portable calibrator used for the in situ calibration of the instrument. The extensometer is very sensitive. Its scale factor is 2.093±0.032 nm/mV according to the highly precise calibration method developed at the GGRI. Since the stability of extensometers is strongly influenced by the geological structure and properties of the rocks in the vicinity of the recording site, the observatory instrument system was tested by coherence analysis between theoretical (as the input signal) and measured tidal data series (as the output signal). In the semidiurnal tidal frequency band the coherence is better than 0.95, while in the diurnal band it is about 0.8. Probably this is due to the fact that the noise is higher in the diurnal band (0.4–0.5 nstr) than in the semidiurnal band (0.19–0.22 nstr). Coherence analysis between theoretical and measured data corrected for barometric changes yielded a small improvement of coherence in both frequency bands, while using temperature data correction, no observable improvement was obtained. Results of the tidal analysis also show that the observatory instrument system is suitable for recording very small tectonic movements. The 18 years of continuous data series measured by the extensometer prove the high quality of the extensometer. On the basis of investigations, it was pointed out that further efforts should be done to improve the barometric correction method and that correction for ocean load, as well as considering topographic and cavity effects are necessary to increase the accuracy of determining tidal parameters.
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07.10.-h Mechanical instruments and equipment
91.10.Tq Earth tides
91.45.-c Tectonophysics
06.20.fb Standards and calibration
back to top Electronics; Electromagnetic Technology; Microwaves

Adapting TESLA technology for future cw light sources using HoBiCaT

O. Kugeler, A. Neumann, W. Anders, and J. Knobloch

Rev. Sci. Instrum. 81, 074701 (2010); doi:10.1063/1.3443561 (9 pages)

Online Publication Date: 12 July 2010

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The HoBiCaT facility has been set up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities in cw mode of operation and it was successfully demonstrated that TESLA pulsed technology can be used for cw mode of operation with only minor changes. Issues that were addressed comprise of elevated dynamic thermal losses in the cavity walls, necessary modifications in the cryogenics and the cavity processing, the optimum choice of operational parameters such as cavity temperature or bandwidth, the characterization of higher order modes in the cavity, and the usability of existing tuners and couplers for cw.
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42.72.-g Optical sources and standards
85.25.-j Superconducting devices
84.40.Az Waveguides, transmission lines, striplines

Calorimetric method of ac loss measurement in a rotating magnetic field

P. K. Ghoshal, T. A. Coombs, and A. M. Campbell

Rev. Sci. Instrum. 81, 074702 (2010); doi:10.1063/1.3458003 (8 pages)

Online Publication Date: 15 July 2010

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A method is described for calorimetric ac-loss measurements of high-Tc superconductors (HTS) at 80 K. It is based on a technique used at 4.2 K for conventional superconducting wires that allows an easy loss measurement in parallel or perpendicular external field orientation. This paper focuses on ac loss measurement setup and calibration in a rotating magnetic field. This experimental setup is to demonstrate measuring loss using a temperature rise method under the influence of a rotating magnetic field. The slight temperature increase of the sample in an ac-field is used as a measure of losses. The aim is to simulate the loss in rotating machines using HTS. This is a unique technique to measure total ac loss in HTS at power frequencies. The sample is mounted on to a cold finger extended from a liquid nitrogen heat exchanger (HEX). The thermal insulation between the HEX and sample is provided by a material of low thermal conductivity, and low eddy current heating sample holder in vacuum vessel. A temperature sensor and noninductive heater have been incorporated in the sample holder allowing a rapid sample change. The main part of the data is obtained in the calorimetric measurement is used for calibration. The focus is on the accuracy and calibrations required to predict the actual ac losses in HTS. This setup has the advantage of being able to measure the total ac loss under the influence of a continuous moving field as experienced by any rotating machines.
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74.81.-g Inhomogeneous superconductors and superconducting systems, including electronic inhomogeneities
07.20.Fw Calorimeters
06.20.fb Standards and calibration

Solid-state Marx based two-switch voltage modulator for the On-Line Isotope Mass Separator accelerator at the European Organization for Nuclear Research

L. M. Redondo, J. Fernando Silva, H. Canacsinh, N. Ferrão, C. Mendes, R. Soares, J. Schipper, and A. Fowler

Rev. Sci. Instrum. 81, 074703 (2010); doi:10.1063/1.3461134 (6 pages)

Online Publication Date: 19 July 2010

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A new circuit topology is proposed to replace the actual pulse transformer and thyratron based resonant modulator that supplies the 60 kV target potential for the ion acceleration of the On-Line Isotope Mass Separator accelerator, the stability of which is critical for the mass resolution downstream separator, at the European Organization for Nuclear Research. The improved modulator uses two solid-state switches working together, each one based on the Marx generator concept, operating as series and parallel switches, reducing the stress on the series stacked semiconductors, and also as auxiliary pulse generator in order to fulfill the target requirements. Preliminary results of a 10 kV prototype, using 1200 V insulated gate bipolar transistors and capacitors in the solid-state Marx circuits, ten stages each, with an electrical equivalent circuit of the target, are presented, demonstrating both the improved voltage stability and pulse flexibility potential wanted for this new modulator.
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29.20.-c Accelerators
84.30.Jc Power electronics; power supply circuits
84.32.Dd Connectors, relays, and switches
84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors

Simple nonlinearity evaluation and modeling of low-noise amplifiers with application to radio astronomy receivers

F. J. Casas, J. P. Pascual, M. L. de la Fuente, E. Artal, and J. Portilla

Rev. Sci. Instrum. 81, 074704 (2010); doi:10.1063/1.3463295 (6 pages)

Online Publication Date: 27 July 2010

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This paper describes a comparative nonlinear analysis of low-noise amplifiers (LNAs) under different stimuli for use in astronomical applications. Wide-band Gaussian-noise input signals, together with the high values of gain required, make that figures of merit, such as the 1 dB compression (1 dBc) point of amplifiers, become crucial in the design process of radiometric receivers in order to guarantee the linearity in their nominal operation. The typical method to obtain the 1 dBc point is by using single-tone excitation signals to get the nonlinear amplitude to amplitude (AM-AM) characteristic but, as will be shown in the paper, in radiometers, the nature of the wide-band Gaussian-noise excitation signals makes the amplifiers present higher nonlinearity than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNA’s nominal operation, the 1 dBc point has to be obtained, but using realistic excitation signals. In this work, an analytical study of compression effects in amplifiers due to excitation signals composed of several tones is reported. Moreover, LNA nonlinear characteristics, as AM-AM, total distortion, and power to distortion ratio, have been obtained by simulation and measurement with wide-band Gaussian-noise excitation signals. This kind of signal can be considered as a limit case of a multitone signal, when the number of tones is very high. The work is illustrated by means of the extraction of realistic nonlinear characteristics, through simulation and measurement, of a 31 GHz back-end module LNA used in the radiometer of the QUIJOTE (Q U I JOint TEnerife) CMB experiment.
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95.55.Jz Radio telescopes and instrumentation; heterodyne receivers
98.70.Vc Background radiations
back to top Thermometry; Thermal Diffusivity; Acoustics; Photothermal and Photoacoustic

The effect of volume fraction concentration on the thermal conductivity and thermal diffusivity of nanofluids: Numerical and experimental

Faris Mohammed Ali, W. Mahmood Mat Yunus, Mohd Maarof Moksin, and Zainal Abidin Talib

Rev. Sci. Instrum. 81, 074901 (2010); doi:10.1063/1.3458011 (9 pages)

Online Publication Date: 14 July 2010

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This article reports on the effect of aluminum (Al) volume fraction concentration on the thermal conductivity and thermal diffusivity of Al nanoparticles suspended in water, ethylene glycol, and ethanol based fluids prepared by the one step method. The Al nanoparticles were independently produced and then mixed with a base fluid to produce the nanoparticles suspension. The thermal conductivity and thermal diffusivity of the nanofluids were measured using the hot wire-laser beam displacement technique. The thermal conductivity and thermal diffusivity were obtained by fitting the experimental data to the numerical data simulated for Al in distilled water, ethylene glycol, and ethanol. The thermal conductivity and thermal diffusivity of the nanofluids increase with an increase in the volume fraction concentration.
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47.85.Np Fluidics
07.10.Cm Micromechanical devices and systems
05.70.Ce Thermodynamic functions and equations of state
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Time-resolved ellipsometry for studies of heat transfer at liquid/solid and gas/solid interfaces

Chang-Ki Min, David G. Cahill, and Steve Granick

Rev. Sci. Instrum. 81, 074902 (2010); doi:10.1063/1.3465329 (7 pages)

Online Publication Date: 28 July 2010

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We describe a sensitive method for measuring time-dependent changes in refractive index within ∼ 5 μm of an interface using off-null time-resolved ellipsometry and a dual-cavity femtosecond laser. The sensitivity to changes in refractive index is two orders of magnitude higher than conventional picosecond interferometry. A thin metal film on a sapphire substrate is heated by ∼ 10 K using an ultrafast optical pump pulse; the subsequent changes of the phase difference δΔ between math and math polarized reflectivity are tracked using off-null ellipsometry using a time-delayed probe pulse. We demonstrate a sensitivity of δΔ ≈ 3×10−7 deg/√Hz using interfaces between Au and water, and Au and various gases including R134a, a common refrigerant. Our data for the damping rate of ≈200 MHz frequency acoustic waves in O2, N2, and Ar at atmospheric pressure agree well with prior results obtained at much lower pressures and frequencies.
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42.62.-b Laser applications
47.27.te Turbulent convective heat transfer
back to top General Instruments

A simple air system for temperature stabilization in the range −10 to +80 °C for use in NMR spectroscopy

A. V. Anisimov and N. R. Dautova

Rev. Sci. Instrum. 81, 075101 (2010); doi:10.1063/1.3455826 (4 pages)

Online Publication Date: 2 July 2010

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This paper proposes a design for a system of temperature stabilization within the range from −10 to +80±0.5 °C for NMR spectrometers which is simple and affordable to fabricate in a laboratory. The design utilizes a closed system of circulation of an air heat carrier, twofold flow around the thermostabilized system, cooling element on Peltier thermal modules, and a proportional-integral-derivative regulator.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
FREE

Inductive conductivity tensor measurement for flowline or material samples

John L. Kickhofel, Amine Mohamide, Jonatan Jalfin, Joshua Gibson, Philip Thomas, Gerald Minerbo, Hanming Wang, and Dean M. Homan

Rev. Sci. Instrum. 81, 075102 (2010); doi:10.1063/1.3449320 (9 pages)

Online Publication Date: 2 July 2010

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Present-day galvanic-based electrical conductivity measurements are hampered by limitations and necessary corrections, especially in the domain of geological core analysis. Low-accuracy techniques such as crucible, two-electrode, and four-electrode are constricted by current-path requirements, while high-accuracy techniques are time consuming and have limited domains of applicability. We present a novel apparatus capable of electrical conductivity tensor measurements in a noninvasive, noncontact, inductive manner with resolution from 5 mS/m. Inspired by the triaxial induction logging technology appearing in the oil patch today, our apparatus is naturally applicable in a novel way not only to anisotropic geological core analysis but also to arbitrary material samples and flowline systems.
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
93.85.-q Instruments and techniques for geophysical research: Exploration geophysics

Power spectrum analysis with least-squares fitting: Amplitude bias and its elimination, with application to optical tweezers and atomic force microscope cantilevers

Simon F. Nørrelykke and Henrik Flyvbjerg

Rev. Sci. Instrum. 81, 075103 (2010); doi:10.1063/1.3455217 (16 pages)

Online Publication Date: 6 July 2010

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Optical tweezers and atomic force microscope (AFM) cantilevers are often calibrated by fitting their experimental power spectra of Brownian motion. We demonstrate here that if this is done with typical weighted least-squares methods, the result is a bias of relative size between −2/n and +1/n on the value of the fitted diffusion coefficient. Here, n is the number of power spectra averaged over, so typical calibrations contain 10%–20% bias. Both the sign and the size of the bias depend on the weighting scheme applied. Hence, so do length-scale calibrations based on the diffusion coefficient. The fitted value for the characteristic frequency is not affected by this bias. For the AFM then, force measurements are not affected provided an independent length-scale calibration is available. For optical tweezers there is no such luck, since the spring constant is found as the ratio of the characteristic frequency and the diffusion coefficient. We give analytical results for the weight-dependent bias for the wide class of systems whose dynamics is described by a linear (integro)differential equation with additive noise, white or colored. Examples are optical tweezers with hydrodynamic self-interaction and aliasing, calibration of Ornstein–Uhlenbeck models in finance, models for cell migration in biology, etc. Because the bias takes the form of a simple multiplicative factor on the fitted amplitude (e.g. the diffusion coefficient), it is straightforward to remove and the user will need minimal modifications to his or her favorite least-squares fitting programs. Results are demonstrated and illustrated using synthetic data, so we can compare fits with known true values. We also fit some commonly occurring power spectra once-and-for-all in the sense that we give their parameter values and associated error bars as explicit functions of experimental power-spectral values.
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07.10.Cm Micromechanical devices and systems
02.70.Hm Spectral methods
02.70.Rr General statistical methods
42.50.Wk Mechanical effects of light on material media, microstructures and particles

Frequency-feature based antistrong-disturbance signal processing method and system for vortex flowmeter with single sensor

Ke-Jun Xu, Qing-Lin Luo, Gang Wang, San-Shan Liu, and Yi-Bo Kang

Rev. Sci. Instrum. 81, 075104 (2010); doi:10.1063/1.3455204 (7 pages)

Online Publication Date: 14 July 2010

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Digital signal processing methods have been applied to vortex flowmeter for extracting the useful information from noisy output of the vortex flow sensor. But these approaches are unavailable when the power of the mechanical vibration noise is larger than that of the vortex flow signal. In order to solve this problem, an antistrong-disturbance signal processing method is proposed based on frequency features of the vortex flow signal and mechanical vibration noise for the vortex flowmeter with single sensor. The frequency bandwidth of the vortex flow signal is different from that of the mechanical vibration noise. The autocorrelation function can represent bandwidth features of the signal and noise. The output of the vortex flow sensor is processed by the spectrum analysis, filtered by bandpass filters, and calculated by autocorrelation function at the fixed delaying time and at τ = 0 to obtain ratios. The frequency corresponding to the minimal ratio is regarded as the vortex flow frequency. With an ultralow-power microcontroller, a digital signal processing system is developed to implement the antistrong-disturbance algorithm, and at the same time to ensure low-power and two-wire mode for meeting the requirement of process instrumentation. The water flow-rate calibration and vibration test experiments are conducted, and the experimental results show that both the algorithm and system are effective.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
07.68.+m Photography, photographic instruments; xerography

A high-temperature high-pressure calorimeter for determining heats of solution up to 623 K

Essmaiil Djamali, Peter J. Turner, Richard C. Murray, Jr., and James W. Cobble

Rev. Sci. Instrum. 81, 075105 (2010); doi:10.1063/1.3462966 (6 pages)

Online Publication Date: 21 July 2010

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A high-temperature high-pressure isoperibol calorimeter for determining the heats of solution and reaction of very dilute substances in water (10−4 m) at temperatures up to 623 K is described. The energies of vaporization of water at steam saturation pressure were measured as a function of temperature and the results agree with the corresponding values from steam tables to better than 0.08±0.18%. The novelties of the present instrument relative to flow type heat capacity calorimeters are that measurements can be made at orders of magnitude lower concentrations and that measurement of heat of reaction involving solids or gases or in the presence of high concentrations of supporting electrolytes, acids, and bases is possible. Furthermore, the advantage of using enthalpy data over heat capacity data for calculations of the standard state Gibbs free energies of electrolytes is that the experimental heat data of this research need only be integrated once to derive higher temperature free energy data from lower temperatures. The derived heat capacities can be used mathematically to obtain free energies by double integration. However, the resulting errors are much smaller than if experimental aqueous heat capacities were used for the integrations.
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07.20.Fw Calorimeters
82.45.Gj Electrolytes
05.70.Ce Thermodynamic functions and equations of state

rf power system for thrust measurements of a helicon plasma source

Alexander W. Kieckhafer and Mitchell L. R. Walker

Rev. Sci. Instrum. 81, 075106 (2010); doi:10.1063/1.3460263 (8 pages)

Online Publication Date: 22 July 2010

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A rf power system has been developed, which allows the use of rf plasma devices in an electric propulsion test facility without excessive noise pollution in thruster diagnostics. Of particular importance are thrust stand measurements, which were previously impossible due to noise. Three major changes were made to the rf power system: first, the cable connection was changed from a balanced transmission line to an unbalanced coaxial line. Second, the rf power cabinet was placed remotely in order to reduce vibration-induced noise in the thrust stand. Finally, a relationship between transmission line length and rf was developed, which allows good transmission of rf power from the matching network to the helicon antenna. The modified system was tested on a thrust measurement stand and showed that rf power has no statistically significant contribution to the thrust stand measurement.
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52.50.Dg Plasma sources

Temperature dependent thermoelectric material power factor measurement system

Jonathan D’Angelo, Adam Downey, and Timothy Hogan

Rev. Sci. Instrum. 81, 075107 (2010); doi:10.1063/1.3465326 (4 pages)

Online Publication Date: 22 July 2010

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Thermoelectric materials can be used for cooling/heating applications, or converting waste heat into electricity. Novel thermoelectric materials have been discovered in recent years. Characterization of an electrical conductivity and thermopower of a sample from room temperature to ≥ 900 K is often necessary for thermoelectric materials. This paper describes a system built for measurement of the power factor of thermoelectric materials from 300 to 1273 K. Characterization results of the system are also presented.
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84.60.-h Direct energy conversion and storage
07.20.Hy Furnaces; heaters

Two-dimensional dielectric spectroscopy: Implementation and validation of a scanning open-ended coaxial probe

Mohammad Habibi, David P. Klemer, and Valerica Raicu

Rev. Sci. Instrum. 81, 075108 (2010); doi:10.1063/1.3462974 (10 pages)

Online Publication Date: 23 July 2010

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Dielectric spectroscopy is a powerful tool for characterizing and classifying materials based on their electrical properties. In order to perform dielectric measurements on a sample with spatially varying properties, the measuring probe typically is repositioned manually on the surface of the sample for each measurement. In this paper, we present a novel technique, based on a reconfigurable multielectrode array, which facilitates the recording of measurements at various different spatial locations without physically moving the measuring electrodes. By electronically selecting one of the electrodes as the inner line and connecting the remainder of the electrodes together to form the outer line, an open-ended coaxial probe is created, which can be repositioned by simply selecting different electrode combinations; hence the name of a “traveling” coaxial probe. The geometric factor, or the cell constant, of each coaxial probe in the array was estimated from measurements on saline solutions with known electrical characteristics. In order to validate the setup for measurement of dielectric properties of biological cells, the plasma membrane capacitance and cytoplasm conductivity of yeast cells suspended in aqueous solutions were measured and compared to results from published reports. Dielectric spectroscopy imaging was carried out on tissue phantoms made of an agar gel with inclusions consisting of concentrated yeast cell suspensions. Measurements were performed on the phantoms, and the dielectric data were spatially mapped with respect to electrode location. The spatial electrical data correlated precisely with locations of yeast cell inclusions within the phantoms.
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77.22.-d Dielectric properties of solids and liquids

Fast scanning cavity offset lock for laser frequency drift stabilization

Nicolas Seymour-Smith, Peter Blythe, Matthias Keller, and Wolfgang Lange

Rev. Sci. Instrum. 81, 075109 (2010); doi:10.1063/1.3455830 (5 pages)

Online Publication Date: 26 July 2010

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We have implemented a compact setup for long-term laser frequency stabilization. Light from a stable reference laser and several slave lasers is coupled into a confocal Fabry–Pérot resonator. By stabilizing the position of the transmission peaks of the slave lasers relative to successive peaks of the master laser as the length of the cavity is scanned over one free spectral range, the long-term stability of the master laser is transferred to the slave lasers. By using fast analog peak detection and low-latency microcontroller-based digital feedback, with a scanning frequency of 3 kHz, we obtain a feedback bandwidth of 380 Hz and a relative stability of better than 10 kHz at timescales longer than 1 s, a significant improvement on previous scanning-cavity stabilization systems.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking

A new magnetron based gas aggregation source of metal nanoclusters coupled to a double time-of-flight mass spectrometer system

Tahzeeb Momin and Ashok Bhowmick

Rev. Sci. Instrum. 81, 075110 (2010); doi:10.1063/1.3465304 (10 pages)

Online Publication Date: 28 July 2010

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A new magnetron based gas-aggregation source for continuous production of metal nanoclusters has been built and coupled to a double time-of-flight mass spectrometer system. The capability of the source to produce neutral, positive, and negative nanoclusters within one production cycle, particularly under the same optimized experimental conditions, has been tested. The source performs steadily for continuous long operations and has high beam intensity that would be preferable for size selective measurements in gas phase on individual nanoclusters. This paper describes on the instrumentation of the integrated complete experimental setup for gas-phase measurement on nanoclusters including the source. It reports on the production of copper nanoclusters using the source. Mass abundances of neutral and charged clusters have been investigated and the results are discussed with respect to reported results using various other types of sources. The experimental isotopic distributions of 63Cu versus 65Cu within individual cluster mass peaks have been derived and compared to corresponding theoretical profiles.
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07.75.+h Mass spectrometers
85.35.-p Nanoelectronic devices
84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)

Stand alone experimental setup for dc transport measurements

A. V. Suslov

Rev. Sci. Instrum. 81, 075111 (2010); doi:10.1063/1.3463691 (4 pages)

Online Publication Date: 28 July 2010

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Described is a system consisted of Keithley’s current source Model 6221 and nanovoltmeter Model 2182A pairs. That pair was developed by Keithley for precise measurements of a sample’s one electrical parameter by the dc current-reversal transport technique. Nonstandard synchronization method employed in the presented setup allows assembling several pairs together for low level electrical measurements of a sample’s several parameters associated with the same current, thus expanding the applications of these devices. The equipment was tested by simultaneous measurements of such two parameters as transverse magnetoresistance and Hall voltage on the following materials: Si/SiGe, Ge:Mn; HgTe/HgCdTe, and InMnSb.
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)

Symmetric miniaturized heating system for active microelectronic devices

Michael McCracken, Michael Mayer, Isaac Jourard, Jeong-Tak Moon, and John Persic

Rev. Sci. Instrum. 81, 075112 (2010); doi:10.1063/1.3469794 (6 pages)

Online Publication Date: 29 July 2010

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To qualify interconnect technologies such as microelectronic fine wire bonds for mass production of integrated circuit (IC) packages, it is necessary to perform accelerated aging tests, e.g., to age a device at an elevated temperature or to subject the device to thermal cycling and measure the decrease of interconnect quality. There are downsides to using conventional ovens for this as they are relatively large and have relatively slow temperature change rates, and if electrical connections are required between monitoring equipment and the device being heated, they must be located inside the oven and may be aged by the high temperatures. Addressing these downsides, a miniaturized heating system (minioven) is presented, which can heat individual IC packages containing the interconnects to be tested. The core of this system is a piece of copper cut from a square shaped tube with high resistance heating wire looped around it. Ceramic dual in-line packages are clamped against either open end of the core. One package contains a Pt100 temperature sensor and the other package contains the device to be aged placed in symmetry to the temperature sensor. According to the temperature detected by the Pt100, a proportional-integral-derivative controller adjusts the power supplied to the heating wire. The system maintains a dynamic temperature balance with the core hot and the two symmetric sides with electrical connections to the device under test at a cooler temperature. Only the face of the package containing the device is heated, while the socket holding it remains below 75 °C when the oven operates at 200 °C. The minioven can heat packages from room temperature up to 200 °C in less than 5 min and maintain this temperature at 28 W power. During long term aging, a temperature of 200 °C was maintained for 1120 h with negligible resistance change of the heating wires after 900 h (heating wire resistance increased 0.2% over the final 220 h). The device is also subjected to 5700 thermal cycles between 55 and 195 °C, demonstrating reliability under thermal cycling.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
07.20.Dt Thermometers

A test cassette for x-ray-exposure experiments at the National Ignition Facility

K. B. Fournier, J. Celeste, V. Rekow, D. R. Bopp, M. J. May, J. H. Fisher, R. Horton, C. D. Newlander, P. Jenkins, and K. Trautz

Rev. Sci. Instrum. 81, 075113 (2010); doi:10.1063/1.3470684 (9 pages)

Online Publication Date: 30 July 2010

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We present the design and operation of a test cassette for exposure of samples to radiation environments at the National Ignition Facility. The cassette provides options for square and round samples and exposure areas; the cassette provides for multiple levels of filtration on a single sample, which allows dynamic range in experiments. The samples had normal lines of sight to the x-ray source in order to have uniform x-ray illumination. The incident x-radiation onto the samples was determined by the choice of filter thicknesses and materials. The samples were held at precise locations, accurate to within a few hundred microns, in the target chamber in order to have a known fluence incident. In the cassette, the samples were held in place in such a way that a minimal “line contact” allows them to have the maximal mechanical response to the x-ray load. We present postshot images of the debris found on films used for filters, and pre- and postexposure specimens.
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07.85.-m X- and γ-ray instruments

Global Event-identifier Module: A distributed digital approach to event-of-interest identification logic for physics experiments

Kusum Rani and E. T. Subramaniam

Rev. Sci. Instrum. 81, 075114 (2010); doi:10.1063/1.3430070 (7 pages)

Online Publication Date: 30 July 2010

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The demands from current data acquisition systems are to acquire data from a large number of detectors (or signals) while providing a high throughput. This can be achieved by having some preprocessing capability in the data acquisition system so that it can identify the events of interest. Precise selection of events with minimal time for identification and preprocessing is an experimental challenge. To address this challenge, we have developed a “Global Event-identifier Module” (GEM) on the CAMAC platform, which can flexibly adapt to the experimental requirements and validate an event with minimal time. GEM is a single width CAMAC module capable of operating in a “distributed” data acquisition environment where multiple CAMAC crates (each with one GEM module) can be used to collect synchronized data from all the crates. Event-of-interest decision can be made on signals connected to different crates. Inter-GEM communication is via the ubiquitous ethernet (unshielded twisted pair, CAT5) cable. The event of interest is decided within 32 ns (excluding cable delay). Implementation is accomplished using field programmable gate array which enables greater flexibility for algorithm modifications and updates without hardware changes. GEM supports unified, distributed, and multi-strobe data acquisition, enabling higher throughput, with data collection from a large number of signals by selective reads of events of interest as determined by the experimenter while providing timestamped data of each event.
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07.05.Hd Data acquisition: hardware and software
29.85.Ca Data acquisition and sorting
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Note: Supplements and corrections to the generalized conic flexure hinge model

Guimin Chen, Yunlei Du, and Xiaoyuan Liu

Rev. Sci. Instrum. 81, 076101 (2010); doi:10.1063/1.3460270 (2 pages)

Online Publication Date: 15 July 2010

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Some supplementary equations have been provided for the generalized model for conic flexure hinges [ G. Chen et al., Rev. Sci. Instrum. 80, 055106 (2009) ] for the purpose of avoiding division-by-zero issues (having zeros in their denominators) in programming languages such as MATLAB, C, and FORTRAN. Some typos have been corrected as well. In comparison, these equations are more concise and effective.
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89.20.Kk Engineering
46.35.+z Viscoelasticity, plasticity, viscoplasticity

Note: New design of a cryogenic linear radio frequency multipole trap

Oskar Asvany, Frank Bielau, Damian Moratschke, Jürgen Krause, and Stephan Schlemmer

Rev. Sci. Instrum. 81, 076102 (2010); doi:10.1063/1.3460265 (3 pages)

Online Publication Date: 16 July 2010

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A new design of a cryogenic linear 22-pole ion trap has been constructed and tested. It is essentially a copper housing to which opposite inner walls two electrode sets are attached via sapphire insulators. These stainless steel electrodes are electroformed in one piece to guarantee good heat conduction. Connected to an external coil, they form an LC-circuit of about 19 MHz resonance frequency. This circuit is excited with a rf power supply made of a commercial digital synthesizer followed by a 10 W amplifier. Buffer gas-cooled H2D+ ions have been stored in this trap at a nominal trap temperature of 14 K. Spectroscopy of the ions confirmed that the kinetic (Doppler) temperature is in reasonable agreement with this value.
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29.25.-t Particle sources and targets
84.30.Le Amplifiers
84.30.Bv Circuit theory

Note: Microelectromechanical systems Coulter counter for cell monitoring and counting

Yifan Wu, James D. Benson, John K. Critser, and Mahmoud Almasri

Rev. Sci. Instrum. 81, 076103 (2010); doi:10.1063/1.3462327 (3 pages)

Online Publication Date: 19 July 2010

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This note describes the design, fabrication, and testing of a novel microelectromechanical systems Coulter counter. The Coulter counter will be used to detect and monitor impedance changes of cells as a function of time in response to different experimental extracellular environments. The device consists of SU-8 (negative photoresist) microchannels, vertical electroplated electrodes, polydimethylsiloxane cover, and is divided into a passive mixing region, a focusing region using negative dielectrophoretic forces, and a measuring region defined by multiple electroplated electrode pairs. The devices were tested using both microbeads in saline water and fibroblast cells in phosphate buffered saline solution. The results show that the proposed microsystem is capable of monitoring impedance of cells at different positions along the Coulter microchannel.
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87.16.-b Subcellular structure and processes
87.85.-d Biomedical engineering
07.10.Cm Micromechanical devices and systems

Note: A thermally stable tension meter for atmospheric soundings using kites

K. T. Walesby and R. G. Harrison

Rev. Sci. Instrum. 81, 076104 (2010); doi:10.1063/1.3465560 (3 pages)

Online Publication Date: 21 July 2010

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Kites offer considerable potential as wind speed sensors—a role distinct from their traditional use as instrument-carrying platforms. In the sensor role, wind speed is measured by kite-line tension. A kite tether line tension meter is described here, using strain gauges mounted on an aluminum ring in a Wheatstone bridge electronic circuit. It exhibits a linear response to tension (19.5 mV N−1) with good thermal stability (mean drift of −0.18 N °C−1 over 5–45 °C temperature range) and a rapid time response (0.2 s or better). Field comparisons of tether line tension for a Rokkaku kite with a fixed tower sonic anemometer show an approximately linear tension-wind speed relationship over the range 1–6 ms−1.
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93.85.-q Instruments and techniques for geophysical research: Exploration geophysics
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
92.60.Gn Winds and their effects

Note: Thermal properties of magnesium in the 60–150 mK range

M. Galeazzi, D. F. Bogorin, K. Prasai, Y. Uprety, and D. McCammon

Rev. Sci. Instrum. 81, 076105 (2010); doi:10.1063/1.3465561 (3 pages)

Online Publication Date: 27 July 2010

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Refrigerators for space and other applications working around 100 mK require lightweight components with good thermal properties. We have measured the thermal properties of high-purity (99.95%) magnesium, which is five times lighter than copper, over the 60–150 mK range and found that it is well-behaved down to these temperatures. Both conductivity and heat capacity are in good agreement with extrapolations from measurements at higher temperatures. The heat capacity per unit volume is about the same as copper and the thermal conductivity about 2.7 times lower than copper of similar residual resistivity ratio, as expected from magnesium’s higher room-temperature resistivity.
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66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
65.40.Ba Heat capacity
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Publisher's Note: “The MaPLE device of Saha Institute of Nuclear Physics: Construction and its plasma aspects” [ Rev. Sci. Instrum. 81, 073507 (2010) ]

Rabindranath Pal, Subir Biswas, Subhasis Basu, Monobir Chattopadhyay, Debjyoti Basu, and Manis Chaudhuri

Rev. Sci. Instrum. 81, 079901 (2010); doi:10.1063/1.3479579 (1 page)

Online Publication Date: 30 July 2010

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Abstract Unavailable
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52.75.-d Plasma devices
52.50.-b Plasma production and heating
52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma
52.25.-b Plasma properties
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
99.10.Fg Publisher's note
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