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Apr 2007

Volume 78, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Rev. Sci. Instrum. 78, 011301 (2007); http://dx.doi.org/10.1063/1.2403783 (10 pages)

S. Marchesini
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Two-frequency acousto-optic modulator driver to improve the beam pointing stability during intensity ramps

B. Fröhlich, T. Lahaye, B. Kaltenhäuser, H. Kübler, S. Müller, T. Koch, M. Fattori, and T. Pfau

Rev. Sci. Instrum. 78, 043101 (2007); http://dx.doi.org/10.1063/1.2720725 (4 pages) | Cited 2 times

Online Publication Date: 2 April 2007

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We report on a scheme to improve the pointing stability of the first order beam diffracted by an acousto-optic modulator (AOM). Due to thermal effects inside the crystal, the angular position of the beam can change by as much as 1 mrad when the radio-frequency power in the AOM is reduced to decrease the first order beam intensity. This is done, for example, to perform forced evaporative cooling in ultracold atom experiments using far-off-resonant optical traps. We solve this problem by driving the AOM with two radio frequencies f1 and f2. The power of f2 is adjusted relative to the power of f1 to keep the total power constant. Using this, the beam displacement is decreased by a factor of 20. The method is simple to implement in existing experimental setups, without any modification of the optics.
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42.79.Jq Acousto-optical devices
42.79.Hp Optical processors, correlators, and modulators
37.10.De Atom cooling methods
37.10.Gh Atom traps and guides

Simple technique for obtaining photoacoustic spectra corrected for the spectral variation of the source in single scan

K. Sathiyamoorthy, C. Vijayan, and M. P. Kothiyal

Rev. Sci. Instrum. 78, 043102 (2007); http://dx.doi.org/10.1063/1.2721409 (4 pages)

Online Publication Date: 12 April 2007

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A simple technique is presented to obtain normalized photoacoustic (PA) spectra corrected for the spectral variation of the source in a single scan. The input light beam is passed through the center of a dual slot chopper, which splits it into two chopped output beams at two different frequencies at a fixed ratio. The beams fall on the sample and the reference kept side-by-side in the same sample chamber. The PA signals are detected by a microphone and processed by two lock-in amplifiers tuned at two different frequencies. The technique is tested by recording the PA spectra of standard samples.
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43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
43.58.Kr Spectrum and frequency analyzers and filters; acoustical and electrical oscillographs; photoacoustic spectrometers; acoustical delay lines and resonators

200 ns pulse high-voltage supply for terahertz field emission

Gregor H. Welsh, David A. Turton, David R. Jones, Dino A. Jaroszynski, and Klaas Wynne

Rev. Sci. Instrum. 78, 043103 (2007); http://dx.doi.org/10.1063/1.2724769 (3 pages) | Cited 2 times

Online Publication Date: 16 April 2007

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We present a method of generating 200 ns high-voltage (up to 40 kV) pulses operating at repetition rates of up to 100 kHz, which may be synchronized with laser pulses. These supplies are simple to make and were developed for ultrafast terahertz pulse generation from GaAs photoconductive antennas using a high-repetition-rate regeneratively amplified laser. We also show an improvement in signal-to-noise ratio over a continuous dc bias field and application of the supply to terahertz pulse generation.
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84.40.-x Radiowave and microwave (including millimeter wave) technology
84.40.Ba Antennas: theory, components and accessories
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Observation of mass analyzed threshold ionization using synchrotron radiation on a new-style time of flight mass spectrometer

Song Zhang, Yanmei Wang, Zhenzhou Cao, Bing Zhang, Sisheng Wang, Ruihong Kong, Yujie Zhao, Xiaobing Shan, and Liusi Sheng

Rev. Sci. Instrum. 78, 043104 (2007); http://dx.doi.org/10.1063/1.2727462 (5 pages) | Cited 1 time

Online Publication Date: 17 April 2007

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We have developed an efficient and applicable apparatus that combines mass-analyzed threshold ionization (MATI) with continuous molecular-beam mass spectrometry using tunable vacuum ultraviolet synchrotron radiation at National Synchrotron Radiation Laboratory. The new design, in which the spoiling field and the pulsed ionization field are perpendicular to each other, can obtain efficiently the ionic spectra of molecule. The MATI spectra of Ar and N2 have been recorded in the energy region between 15.5 and 17.5 eV to illustrate the feasibility of this scheme. With its unique features, the important experiment considerations are potentially a powerful tool for study of information of ionization energies and ionic states of complex organic compounds.
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33.15.Ta Mass spectra
34.50.Gb Electronic excitation and ionization of molecules
07.75.+h Mass spectrometers
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment

Complex impedance measurements of calorimeters and bolometers: Correction for stray impedances

Mark. A. Lindeman, Kathleen A. Barger, Donald E. Brandl, S. Gwynne Crowder, Lindsay Rocks, and Dan McCammon

Rev. Sci. Instrum. 78, 043105 (2007); http://dx.doi.org/10.1063/1.2723066 (5 pages) | Cited 12 times

Online Publication Date: 18 April 2007

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Impedance measurements provide a useful probe of the physics of bolometers and calorimeters. We describe a method for measuring the complex impedance of these devices. In previous work, stray impedances and readout electronics of the measurement apparatus have resulted in artifacts in the impedance data. The technique allows experimenters to find an independent Thevenin or Norton equivalent circuit for each frequency. This method allows experimenters to easily isolate the device impedance from the effects of parasitic impedances and frequency dependent gains in amplifiers.
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
07.20.Fw Calorimeters
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Application of superlattice multipliers for high-resolution terahertz spectroscopy

C. P. Endres, F. Lewen, T. F. Giesen, S. Schlemmer, D. G. Paveliev, Y. I. Koschurinov, V. M. Ustinov, and A. E. Zhucov

Rev. Sci. Instrum. 78, 043106 (2007); http://dx.doi.org/10.1063/1.2722401 (6 pages) | Cited 13 times

Online Publication Date: 30 April 2007

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Frequency multipliers based on superlattice (SL) devices as nonlinear elements have been developed as radiation sources for a terahertz (THz) laboratory spectrometer. Input frequencies of 100 and 250 GHz from backward wave oscillators have been multiplied up to the 11th harmonic, producing usable frequencies up to 2.7 THz. Even at these high frequencies the output power is sufficient for laboratory spectroscopy. Comparisons to conventional high-resolution microwave spectroscopy methods reveal several superior features of this new device such as very high line frequency accuracies, broadband tunability, high output power levels at odd harmonics of the input frequency up to high orders, and a robust applicability.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Nv Optical frequency converters
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Induction charge detector with multiple sensing stages

Manuel Gamero-Castaño

Rev. Sci. Instrum. 78, 043301 (2007); http://dx.doi.org/10.1063/1.2721408 (7 pages) | Cited 7 times

Online Publication Date: 11 April 2007

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An induction charge detector yields the net charge and the time of flight of a particle. The unique ability to independently measure these two parameters sets apart this rather simple detection technique. The main shortcoming of this instrument is its high charge detection limit, resulting from the intrinsic noise of the detector electronics and the low signal associated with the charge to measure. The goal of the present work is to lower the detection limit of this detector. This article describes an induction charge detector whose main novelty is a sequence of aligned cylindrical electrodes for measuring the charge of a particle n times. In a time domain analysis, this feature reduces both the detection limit and the standard error of the charge measurement by factors of math and math. More importantly, sensing stages could be added to arbitrarily lower the detection limit in a frequency domain analysis.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
06.30.Ka Basic electromagnetic quantities

Development of bellows and gate valves with a comb-type rf shield for high-current accelerators: Four-year beam test at KEK B-Factory

Yusuke Suetsugu, Ken-ichi Kanazawa, Kyo Shibata, Mitsuru Shirai, Aleksander E. Bondar, Victor S. Kuzminykh, Aleksander I. Gorbovsky, Kurt Sonderegger, Minoru Morii, and Kakuyu Kawada

Rev. Sci. Instrum. 78, 043302 (2007); http://dx.doi.org/10.1063/1.2723747 (7 pages) | Cited 2 times

Online Publication Date: 12 April 2007

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Since a comb-type rf shield was proposed in 2003 as a rf shield for future high-intensity accelerators, various types of bellow chambers and gate valves with this rf shield have been installed in the KEK B-Factory rings in series and tested with beams. Through beam tests to check the performance, a structural simplification has been tried in parallel. The temperatures of the bellow corrugations decreased by a factor of 3–6 compared to those with a conventional finger-type rf shield in most cases. The temperatures of the body of the gate valves also decreased by a factor of 2–5. These results demonstrated the availability of the comb-type rf shield. Although a discharge was observed in one simplified model, the latest model has shown no problem up to a stored beam current of 1.8 A (1.3 mA/bunch, 6 mm bunch length). Experiences with the comb-type rf shield in these four-year beam tests are reviewed here.
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29.27.Eg Beam handling; beam transport
29.20.db Storage rings and colliders

33.7 MHz heavy-ion radio frequency quadrupole linac at VECC Kolkata

Alok Chakrabarti, Vaishali Naik, Siddhartha Dechoudhury, Arup Bandyopadhyay, Manas Mondal, Hemendra Kumar Pandey, Tapatee Kundu Roy, Dirtha Sanyal, and Debasis Bhowmick

Rev. Sci. Instrum. 78, 043303 (2007); http://dx.doi.org/10.1063/1.2727457 (5 pages) | Cited 3 times

Online Publication Date: 16 April 2007

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A 33.7 MHz heavy-ion radio frequency quadrupole (RFQ) linear accelerator has been designed, built, and tested. It is a four-rod-type RFQ designed for acceleration of 1.38 keV/u, q/A ≥ 1/16 ions to about 29 keV/u. Transmission efficiencies of about 85% and 80% have been measured for the unanalyzed and analyzed beams, respectively, of oxygen (16O2+, 16O3+, 16O4+), nitrogen (14N3+, 14N4+), and argon (40Ar4+). The system design and measurements along with results of beam acceleration test will be presented.
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29.20.-c Accelerators
41.75.Ak Positive-ion beams

Low-energy linear oxygen plasma source

André Anders and George Yu. Yushkov

Rev. Sci. Instrum. 78, 043304 (2007); http://dx.doi.org/10.1063/1.2723753 (7 pages) | Cited 6 times

Online Publication Date: 17 April 2007

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A new version of a constricted plasma source is described, characterized by all metal-ceramic construction, a linear slit exit of 180 mm length, and cw operation (typically 50 kHz) at an average power of 1.5 kW. The plasma source is here operated with oxygen gas, producing streaming plasma that contains mainly positive molecular and atomic ions, and to a much lesser degree, negative ions. The maximum total ion current obtained was about 0.5 A. The fraction of atomic ions reached more than 10% of all ions when the flow rate was less then 10 SCCM O2, corresponding to a chamber pressure of about 0.5 Pa for the selected pumping speed. The energy distribution functions of the different ion species were measured with a combined mass spectrometer and energy analyzer. The time-averaged distribution functions were broad and ranged from about 30 to 90 eV at 200 kHz and higher frequencies, while they were only several eV broad at 50 kHz and lower frequencies, with the maximum located at about 40 eV for the grounded anode case. This maximum was shifted down to about 7 eV when the anode was floating, indicating the important role of the plasma potential for the ion energy for a given substrate potential. The source could be scaled to greater length and may be useful for functionalization of surfaces and plasma-assisted deposition of compound films.
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52.50.Dg Plasma sources
52.25.Fi Transport properties
52.70.Nc Particle measurements
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

New fast beam profile monitor for electron-positron colliders

A. V. Bogomyagkov, V. F. Gurko, A. N. Zhuravlev, P. V. Zubarev, V. A. Kiselev, O. I. Meshkov, N. Yu. Muchnoi, A. N. Selivanov, V. V. Smaluk, and A. D. Khilchenko

Rev. Sci. Instrum. 78, 043305 (2007); http://dx.doi.org/10.1063/1.2720729 (6 pages)

Online Publication Date: 23 April 2007

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A new fast beam profile monitor has been developed at the Budker Institute of Nuclear Physics. This monitor is based on the Hamamatsu multianode photomultiplier with 16 anode strips and provides turn-by-turn measurement of the transverse beam profile. The device is equipped with an internal memory, which has enough capacity to store 131 072 samples of the beam profile. The dynamic range of the beam profile monitor allows us to study turn-by-turn beam dynamics within the bunch charge range from 1 pC up to 10 nC. Using this instrument, we have investigated at the VEPP-4M electron-positron collider a number of beam dynamics effects which cannot be observed by other beam diagnostics tools.
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29.27.Fh Beam characteristics
29.27.Eg Beam handling; beam transport
29.27.Bd Beam dynamics; collective effects and instabilities
85.60.Ha Photomultipliers; phototubes and photocathodes
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Electron energy distribution function in plasma determined using numerical simulations of multiple harmonic components on Langmuir probe characteristic—Efficiency of the method

J. L. Jauberteau and I. Jauberteau

Rev. Sci. Instrum. 78, 043501 (2007); http://dx.doi.org/10.1063/1.2719211 (12 pages) | Cited 2 times

Online Publication Date: 3 April 2007

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The method proposed to determine the electron energy distribution is based on the numerical simulation of the effect induced by a sinusoidal perturbation superimposed to the direct current voltage applied to the probe. The simulation is generating a multiple harmonic components signal over the rough experimental data. Each harmonic component can be isolated by means of finite impulse response filters. Then, the second derivative is deduced from the second harmonic component using the Taylor expansion. The efficiency of the method is proved first on simple cases and second on typical Langmuir probes characteristics recorded in the expansion of a microwave plasma containing argon or nitrogen-hydrogen gas mixture. Results obtained using this method are compared to those, which are determined using a classical Savitzsky–Golay filter.
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52.70.Ds Electric and magnetic measurements
52.65.Vv Perturbative methods
52.50.Dg Plasma sources

Irradiation of cryogenic temperature sensors by gamma dose of 1 MGy

Yu. P. Filippov, V. M. Miklayev, and A. K. Sukhanova

Rev. Sci. Instrum. 78, 043502 (2007); http://dx.doi.org/10.1063/1.2715927 (9 pages)

Online Publication Date: 9 April 2007

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This article presents results of investigations of the cryogenic thermometers which can operate under high radiation environment. To clarify the temperature shifts due to gamma irradiation up to 1 MGy, the platinum (two types), carbon-glass, and TVO temperature sensors have been tested. Before the irradiation run, the selected sensors were calibrated and a series of experiments was carried out under irradiation of the sensors at 77.3 and 293 K when their readings were taken in situ. Afterwards, the postirradiation evolution (short and long time) of the sensors was measured at 4.2, 77.3, and 293 K. The results, depending on the type of the sensor, can be optimistic or pessimistic. Some comparisons with analogous data for fast neutron treatment have also been made.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
61.80.Ed γ-ray effects
07.20.Dt Thermometers

High dynamic range streak camera for subpicosecond time-resolved x-ray spectroscopy

C. Bonté, M. Harmand, F. Dorchies, S. Magnan, V. Pitre, J.-C. Kieffer, P. Audebert, and J.-P. Geindre

Rev. Sci. Instrum. 78, 043503 (2007); http://dx.doi.org/10.1063/1.2720718 (8 pages) | Cited 8 times

Online Publication Date: 11 April 2007

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The full characterization of a time resolved x-ray spectrometer is presented. It is based on the coupling of a conical crystal with a subpicosecond x-ray streak camera. The detector is designed to operate in accumulation mode at high repetition rate (up to 1 kHz) allowing signal to noise ratio as high as 104:1. Optical switches have been used to limit the jitter induced in the subpicosecond range, demonstrating the very long term stability (a few hours) of the entire device. The data analysis have been developed to get the spectral and temporal resolution of an ultrashort laser-plasma-based x-ray source.
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07.85.Nc X-ray and γ-ray spectrometers
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
06.60.Jn High-speed techniques (microsecond to femtosecond)
52.70.La X-ray and γ-ray measurements

Analog integrator for the Korea superconducting tokamak advanced research magnetic diagnostics

J. G. Bak, S. G. Lee, D. Son, and E. M. Ga

Rev. Sci. Instrum. 78, 043504 (2007); http://dx.doi.org/10.1063/1.2721405 (5 pages) | Cited 5 times

Online Publication Date: 11 April 2007

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An analog integrator, which automatically compensates an integrating drift, has been developed for the magnetic diagnostics in the Korea superconducting tokamak advanced research (KSTAR). The compensation of the drift is done by the analog to digital converter-register-digital to analog converter in the integrator. The integrator will be used in the equilibrium magnetic field measurements by using inductive magnetic sensors during a plasma discharge in the KSTAR machine. Two differential amplifiers are added to the signal path between each magnetic sensor and the integrator in order to improve the performance of the integrator because a long signal cable of 100 m will be used for the measurement in the KSTAR machine. In this work, the characteristics of the integrator with two differential amplifiers are experimentally investigated.
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07.55.Ge Magnetometers for magnetic field measurements
52.70.Ds Electric and magnetic measurements
52.55.Fa Tokamaks, spherical tokamaks

Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments

G. S. Sarkisov, S. E. Rosenthal, and K. W. Struve

Rev. Sci. Instrum. 78, 043505 (2007); http://dx.doi.org/10.1063/1.2712938 (5 pages) | Cited 3 times

Online Publication Date: 11 April 2007

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A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good agreement up to the time of melting. Good agreement is also demonstrated with resistive magnetohydrodynamics simulation. A similar thermodynamical calculation for Mo, Ti, Ni, Fe, Al, and Cu shows good agreement with experimental data. The thermodynamical technique is useful for verification of the voltage measurements in exploding wire experiments. This technique also shows good agreement with an exploding W foil experiment.
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52.50.Lp Plasma production and heating by shock waves and compression
52.80.Qj Explosions; exploding wires
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.65.Kj Magnetohydrodynamic and fluid equation
52.25.Kn Thermodynamics of plasmas
52.25.Fi Transport properties

Evolution of the millimeter-wave collective Thomson scattering system of the high-field tokamak Frascati Tokamak Upgrade

U. Tartari, G. Grosso, G. Granucci, F. Gandini, S. Garavaglia, G. Grossetti, A. Simonetto, V. Mellera, V. Muzzini, L. Lubyako, A. Shalashov, F. P. Orsitto, G. Ciccone, and F. Volpe

Rev. Sci. Instrum. 78, 043506 (2007); http://dx.doi.org/10.1063/1.2719197 (11 pages) | Cited 3 times

Online Publication Date: 16 April 2007

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We first describe the improved receiving system of the diagnostic experiment of millimeter-wave collective Thomson scattering being run on the Frascati Tokamak Upgrade (FTU), and then discuss some peculiar problems and new operating procedures related to the investigation of strong anomalous spectra of nonthermal origin, many-orders-of-magnitude stronger than the ion thermal feature merged in them, systematically observed in the experimentation, and finally ascribed to a perturbation of the gyrotron that generates the probing beam. Arguments in favor of a more general valence of the solutions actuated for the specific case of FTU are finally given.
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52.70.Gw Radio-frequency and microwave measurements
52.55.Fa Tokamaks, spherical tokamaks
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.25.Fi Transport properties

Design of multipulse Thomson scattering diagnostic for SST-1 tokamak

Ajai Kumar, Chhaya Chavda, Y. C. Saxena, Ranjeet Singh, Aruna Thakar, Jinto Thomas, Kiran Patel, Kaushal Pandya, and Vijay Bedakihale

Rev. Sci. Instrum. 78, 043507 (2007); http://dx.doi.org/10.1063/1.2724775 (8 pages) | Cited 5 times

Online Publication Date: 16 April 2007

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A multipulse Nd:YAG (Yttrium aluminum garnet) Thomson scattering (TS) system is designed and developed for measuring electron temperature (Te) and density (ne) profiles of SST-1 tokamak. The system operates at vertical, divertor, and horizontal (midplane) regions of plasma and measures the electron temperature of 20 eV to 1.5 keV and density of 1018–1019 m−3. Six Nd:YAG lasers synchronized with external control is used to get three different temporal resolutions (30 Hz, 180 Hz, and 1 kHz). The entire system is laboratory tested for the stability of alignment and performance over a distance of 30 m. Different imaging lens assemblies are designed to image the scattered photons from each of the scattering region to an array of optical fibers. A low cost and compact five-channel interference filter polychromator is designed, fabricated, and tested for its image quality and the filter transmission characteristics. Detection system with an avalanche photodiode and required signal conditioning electronics is developed for detecting the scattered photons. A data acquisition and control module operating on PXI bus is developed for the real time data acquisition and system control. A detailed description of design and testing of TS subsystems is presented in this article.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.55.Fa Tokamaks, spherical tokamaks
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Three-dimensional analysis of microwave generated plasmas with extended planar laser-induced fluorescence

U. Stopper, P. Lindner, and U. Schumacher

Rev. Sci. Instrum. 78, 043508 (2007); http://dx.doi.org/10.1063/1.2722399 (6 pages) | Cited 5 times

Online Publication Date: 18 April 2007

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We present the development and application of a diagnostic system for the analysis of microwave generated low-pressure plasmas, which might also be used for the investigation of the edge regions in magnetically confined fusion plasmas. Our method uses planar laser-induced fluorescence, which is produced by excitation of neutral metastable atoms through a short, intense, pulsed laser. The beam expansion optics consist of an uncommon setup of four lenses. By controlled shifting of an element of the optics sideways, the location of the laser sheet in the plasma is scanned perpendicular to the excitation plane. Together with a spectrometer observing different observation volumes along the beam path, we are able to map absolute three-dimensional (3D) population density distributions of the metastable (2P1/2o) 3s[1/2]0o state of Ne I in an electron cyclotron resonance heating (ECRH) plasma. This optical tomography system was used to study the influence of the microwave power and mode on the spatial structure of the plasma. The results show that the population density of the neutral neon in this metastable state is found to be in the range of 1016 m−3, and that its spatial distribution is associated with the 3D structure of the magnetic field. We also report that the spatial distribution strongly varies with the mode structure, which depends on the microwave power.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.50.Dg Plasma sources
52.40.Hf Plasma-material interactions; boundary layer effects
52.25.Ya Neutrals in plasmas
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating

Plasma rotation measurement in small tokamaks using an optical spectrometer and a single photomultiplier as detector

J. H. F. Severo, I. C. Nascimento, Yu. K. Kuznetov, V. S. Tsypin, R. M. O. Galvão, and M. Tendler

Rev. Sci. Instrum. 78, 043509 (2007); http://dx.doi.org/10.1063/1.2723749 (5 pages) | Cited 1 time

Online Publication Date: 18 April 2007

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The method for plasma rotation measurement in the tokamak TCABR is reported in this article. During a discharge, an optical spectrometer is used to scan sequentially spectral lines of plasma impurities and spectral lines of a calibration lamp. Knowing the scanning velocity of the diffraction grating of the spectrometer with adequate precision, the Doppler shifts of impurity lines are determined. The photomultiplier output voltage signals are recorded with adequate sampling rate. With this method the residual poloidal and toroidal plasma rotation velocities were determined, assuming that they are the same as those of the impurity ions. The results show reasonable agreement with the neoclassical theory and with results from similar tokamaks.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.30.-q Plasma dynamics and flow
52.55.Fa Tokamaks, spherical tokamaks
52.25.Vy Impurities in plasmas
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.25.Fi Transport properties

Localized etching of an insulator film coated on a copper wire using an atmospheric-pressure microplasma jet

Hiroyuki Yoshiki

Rev. Sci. Instrum. 78, 043510 (2007); http://dx.doi.org/10.1063/1.2727488 (4 pages) | Cited 4 times

Online Publication Date: 20 April 2007

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Atmospheric-pressure microplasma jets (APμPJs) of Ar and Ar/O2 gases were generated from the tip of a stainless steel surgical needle having outer and inner diameters of 0.4 and 0.2 mm, respectively, with a rf excitation of 13.56 MHz. The steel needle functions both as a powered electrode and a gas nozzle. The operating power is 1.2–6 W and the corresponding peak-to-peak voltage Vp.p. is about 1.5 kV. The APμPJ was applied to the localized etching of a polyamide-imide insulator film (thickness of 10 μm) of a copper winding wire of 90 μm diameter. The insulator film around the copper wire was completely removed by the irradiated plasma from a certain direction without fusing the wire. The removal time under the Ar APμPJ irradiation was only 3 s at a rf power of 4 W. Fluorescence microscopy and scanning electron microscope images reveal that good selectivity of the insulator film to the copper wire was achieved. In the case of Ar/O2 APμPJ irradiation with an O2 concentration of 10% or more, the removed copper surface was converted to copper monoxide CuO.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
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Effect of contact stiffness on wedge calibration of lateral force in atomic force microscopy

Fei Wang and Xuezeng Zhao

Rev. Sci. Instrum. 78, 043701 (2007); http://dx.doi.org/10.1063/1.2720723 (4 pages) | Cited 7 times

Online Publication Date: 2 April 2007

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Quantitative friction measurement of nanomaterials in atomic force microscope requires accurate calibration method for lateral force. The effect of contact stiffness on lateral force calibration of atomic force microscope is discussed in detail and an improved calibration method is presented. The calibration factor derived from the original method increased with the applied normal load, which indicates that separate calibration should be required for every given applied normal load to keep the accuracy of friction measurement. We improve the original method by introducing the contact factor, which is derived from the contact stiffness between the tip and the sample, to the calculation of calibration factors. The improved method makes the calculation of calibration factors under different applied normal loads possible without repeating the calibration procedure. Comparative experiments on a silicon wafer have been done by both the two methods to validate the method in this article.
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07.79.Lh Atomic force microscopes
06.20.fb Standards and calibration
07.10.Pz Instruments for strain, force, and torque
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.40.Pq Friction, lubrication, and wear
62.20.Qp Friction, tribology, and hardness

Experimental setup for lensless imaging via soft x-ray resonant scattering

Maurizio Sacchi, Carlo Spezzani, Alessandro Carpentiero, Mauro Prasciolu, Renaud Delaunay, Jan Lüning, and François Polack

Rev. Sci. Instrum. 78, 043702 (2007); http://dx.doi.org/10.1063/1.2720726 (6 pages) | Cited 1 time

Online Publication Date: 3 April 2007

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We have developed a setup for measuring holographically formed interference patterns using an integrated sample-mask design. The direct space image of the sample is obtained via a two-dimensional Fourier transform of the x-ray diffraction pattern. We present the details of our setup, commenting on the influence of geometrical parameters on the imaging capabilities. As an example, we present and discuss the results of test experiments on a patterned Co film.
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07.85.-m X- and γ-ray instruments
42.30.Kq Fourier optics

Environmental chamber for an atomic force microscope

J. Lievonen, K. Ranttila, and M. Ahlskog

Rev. Sci. Instrum. 78, 043703 (2007); http://dx.doi.org/10.1063/1.2719598 (4 pages) | Cited 5 times

Online Publication Date: 9 April 2007

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A commercial atomic force microscope (AFM), originally designed for operation in ambient conditions, was placed inside a compact aluminum chamber, which can be pumped down to high vacuum levels or filled with a desired gaseous atmosphere, including humidity, up to normal pressure. The design of this environmental AFM is such that minimal intrusion is made to the original setup, which can be restored easily. The performance inside the environmental chamber is similar to the original version.
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07.79.Lh Atomic force microscopes
07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Calibration of atomic force microscope cantilevers using piezolevers

Saltuk B. Aksu and Joseph A. Turner

Rev. Sci. Instrum. 78, 043704 (2007); http://dx.doi.org/10.1063/1.2719649 (8 pages) | Cited 12 times

Online Publication Date: 12 April 2007

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The atomic force microscope (AFM) can provide qualitative information by numerous imaging modes, but it can also provide quantitative information when calibrated cantilevers are used. In this article a new technique is demonstrated to calibrate AFM cantilevers using a reference piezolever. Experiments are performed on 13 different commercially available cantilevers. The stiff cantilevers, whose stiffness is more than 0.4 N/m, are compared to the stiffness values measured using nanoindentation. The experimental data collected by the piezolever method is in good agreement with the nanoindentation data. Calibration with a piezolever is fast, easy, and nondestructive and a commercially available AFM is enough to perform the experiments. In addition, the AFM laser must not be calibrated. Calibration is reported here for cantilevers whose stiffness lies between 0.08 and 6.02 N/m.
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07.79.Lh Atomic force microscopes
06.20.fb Standards and calibration
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