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Dec 1987

Volume 58, Issue 12, pp. 2217-2346

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Optical double‐balanced quadrature mixer with applications to light‐beating spectroscopy and photon counting

H. C. Burstyn

Rev. Sci. Instrum. 58, 2217 (1987); http://dx.doi.org/10.1063/1.1139326 (9 pages) | Cited 1 time

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A doubly balanced optical quadrature mixer is proposed for use in light‐beating spectroscopy. The technique allows one to examine asymmetric optical spectra. The ratio of the antisymmetric to symmetric spectral densities can be found directly. The use of the device in the photon‐counting regime is also discussed. The instrument has direct applicability in the measurement of the dynamical properties of hydrodynamic systems out of equilibrium.
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42.79.Ci Filters, zone plates, and polarizers
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
47.80.-v Instrumentation and measurement methods in fluid dynamics

A lidar system for measuring atmospheric pressure and temperature profiles

Geary K. Schwemmer, Mark Dombrowski, C. Laurence Korb, Jeffry Milrod, Harvey Walden, and Robert H. Kagann

Rev. Sci. Instrum. 58, 2226 (1987); http://dx.doi.org/10.1063/1.1139327 (12 pages) | Cited 14 times

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The design and operation of a differential absorption lidar (LIght Detection And Ranging) system capable of remotely measuring the vertical structure of tropospheric pressure and temperature are described. The measurements are based on the absorption by atmospheric oxygen of the spectrally narrowband output of two pulsed alexandrite lasers. Detailed laser output spectral characteristics, which are critical to successful lidar measurements, are presented. Spectral linewidths of 0.026 and 0.018 cm−1 for the lasers were measured with over 99.99% of the energy contained in three longitudinal modes.
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42.68.Wt Remote sensing; LIDAR and adaptive systems
42.79.Qx Range finders, remote sensing devices; laser Doppler velocimeters, SAR, and LIDAR
42.68.Ay Propagation, transmission, attenuation, and radiative transfer
42.68.Bz Atmospheric turbulence effects

Design considerations for the construction of a reflecting symmetric multipass cell for use in laser molecular‐beam experiments

P. G. Lethbridge and A. J. Stace

Rev. Sci. Instrum. 58, 2238 (1987); http://dx.doi.org/10.1063/1.1139328 (6 pages) | Cited 9 times

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A theoretical discussion is presented of the design features that have been incorporated into a multipass cell appropriate for use in laser molecular‐beam experiments. A detailed description of the cell in two dimensions is given, and this is later expanded to highlight the problems of alignment in three dimensions. A prototype cell, constructed using the guidelines presented here, has demonstrated that 31 passes through a molecular beam can be easily achieved. Computer simulations suggest that the optimum potential of the cell is ≊101 passes. The fact that the position of the emergent laser beam is clearly defined makes the cell particularly useful for the purposes of studying absorption spectra.
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Microwave cavity reflection interferometer for single‐pulse transient conductivity measurements

D. J. Eckstrom, M. S. Williams, and J. S. Dickinson

Rev. Sci. Instrum. 58, 2244 (1987); http://dx.doi.org/10.1063/1.1139329 (5 pages) | Cited 2 times

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A technique is described for measuring transient real and imaginary conductivity histories in a single pulse using the microwave cavity perturbation technique when the perturbations are large, that is, when the frequency shift is larger than the FWHM of the cavity resonance and/or when the cavity Q changes significantly. A demonstration of the use of the technique to measure laser photoionization yields in a high‐pressure buffer gas is presented.
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07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)
07.60.Ly Interferometers
07.60.-j Optical instruments and equipment
42.79.-e Optical elements, devices, and systems
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Measurement of charge‐to‐mass ratio (Q/m) distribution of an ionized cluster beam by a special type of quadrupole mass analyzer

Deepak Nayak, Kambiz Pourrezaei, Michel Francois, and Ali Bahasadri

Rev. Sci. Instrum. 58, 2249 (1987); http://dx.doi.org/10.1063/1.1139330 (7 pages)

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Quadrupole mass analyzers (QMA) are the most common type of instruments for the measurement of partial pressures of residual gases in semiconductor industry. The maximum range of this instrument available today is 1–1000 amu, which is equivalent to charge‐to‐mass ratios (Q/m) of 108–105 C/kg. Here, we report in detail the design, construction, and testing of a QMA capable of measuring (Q/m) ratios down to 5 C/kg. This instrument has been used to measure the Q/m distribution of ions, clusters, and microdroplets emitted from a needle‐tip type liquid metal ion source (LMIS). The Q/m distribution of clusters and microdroplets has been found to form a broad peak, and is concentrated mainly between 105 and 103 C/kg. The variation of this distribution as a function of total beam current and beam emission angle has been studied.
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07.75.+h Mass spectrometers
29.25.-t Particle sources and targets
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Magnetic field stabilizer for NMR imaging systems with resistive magnets

J. Weis, V. Jellúš, and I. Frollo

Rev. Sci. Instrum. 58, 2256 (1987); http://dx.doi.org/10.1063/1.1139331 (4 pages) | Cited 1 time

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The NMR stabilizer has been constructed for the purpose of magnetic field stabilization. The error signal for field correction is derived from the 1H resonance of pure H2O. A NMR transducer, operating in the pulse mode with time multiplexing, is connected to the transmit–receive radio frequency stage and yields information about the magnetic induction changes in the frequency form which is compared with the reference frequency. The frequency deviation is evaluated as a voltage that controls the power supply of the electromagnet coil. The stability achieved was slightly better than ±1 ppm.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
07.55.Db Generation of magnetic fields; magnets
85.70.-w Magnetic devices
87.57.-s Medical imaging
87.63.-d Non-ionizing radiation equipment and techniques
87.85.Pq Biomedical imaging

Asymmetric double Langmuir probe: Small signal application

Taner Uckan

Rev. Sci. Instrum. 58, 2260 (1987); http://dx.doi.org/10.1063/1.1139332 (4 pages) | Cited 2 times

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We discuss the asymmetric double Langmuir probe (ADLP) and demonstrate the possibility of using it to measure plasma temperature Te and density n when it is operated in the region of small signal response. The area of one of the ADLP collectors is considerably larger than the other. This probe can be operated at a relatively low applied voltage eVa/Te<1, and still provides sufficient information to determine the plasma Te and n. There is no need for a direct measurement of the ion saturation current, which can be on the order of a few amperes in large fusion devices. This reduces the requirements on the probe power supply.
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07.50.-e Electrical and electronic instruments and components
52.70.Ds Electric and magnetic measurements

Measuring the escaping beam ions from a tokamak plasma

D. Buchenauer, W. W. Heidbrink, L. Roquemore, and K. McGuire

Rev. Sci. Instrum. 58, 2264 (1987); http://dx.doi.org/10.1063/1.1139333 (7 pages) | Cited 4 times

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A new technique using a silicon surface barrier (SSB) diode has been developed for measuring the escaping fast ion flux from a tokamak plasma. Calibration of the detector with an ion beam showed that at a fixed energy the diode’s output current varied linearly with the incident deuteron flux. The diode was mounted inside the PDX vacuum vessel with collimating apertures designed to admit the spiraling orbits of 50‐keV deuterons expelled from the plasma by MHD instabilities. Results from PDX indicated that relative measurements of the escaping fast ion flux due to several plasma instabilities could be made.
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29.40.Wk Solid-state detectors
52.70.Nc Particle measurements
85.30.Hi Surface barrier, boundary, and point contact devices

Hg resonance lamp with controlled 254‐nm line profiles for transient temperature measurements

W. Braun, I. Price, and M. D. Scheer

Rev. Sci. Instrum. 58, 2271 (1987); http://dx.doi.org/10.1063/1.1139334 (3 pages) | Cited 2 times

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A new method has been described elsewhere for measuring transient temperature changes using the absorption of the 254‐nm resonance radiation from an optically thick Hg lamp by traces of Hg vapor. The method is based upon the fact that the Hg resonance lines broaden in a known way with increasing temperature and pressure. The sensitivity and dynamic range of the temperature measurement depends upon the extent of line reversal which varies with the optical depth of the Hg lamp. It is shown here that this can be controlled by means of a proper lamp design. The mounting assembly for the lamp and the circuitry required for this purpose are described. It was demonstrated that the output of such a lamp is stable and reproducible with line profiles (optical densities) that could be varied over about a 20‐fold range. Within such a range of operating parameters, the measurement of transient temperature to 1500 K in gases at pressures below 100 Torr could be made.
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42.72.-g Optical sources and standards
06.20.F- Units and standards
07.20.-n Thermal instruments and apparatus
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Comparison of some glass thermometers at low temperatures in a high magnetic field

S. A. J. Wiegers, R. Jochemsen, C. C. Kranenburg, and G. Frossati

Rev. Sci. Instrum. 58, 2274 (1987); http://dx.doi.org/10.1063/1.1139335 (5 pages) | Cited 12 times

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We have compared the low‐frequency capacitance of glass thermometers of various shapes, made of very pure SiO2 doped with ≊1200 ppm OH−, in the temperature range of 4–100 mK in a magnetic field of 9 T. The construction of the electrodes, the way the contacts are made, and the connection of the leads or cables influence both the voltage and the field dependence of the capacitance and of the loss. We have been able to construct capacitive glass thermometers of which the capacitance is not shifted in a field of 9 T at temperatures down to 4 mK, within our temperature accuracy of ≊5%. This has been determined by comparison with a cerium magnesium nitrate (CMN) thermometer in a field‐free region, and by comparing ultrasound measurements versus the thermometer capacitance with and without a magnetic field.
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07.20.Dt Thermometers
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

New dielectric method for the measurement of physical adsorption of gases at high pressure

T. K. Bose, R. Chahine, L. Marchildon, and J. M. St‐Arnaud

Rev. Sci. Instrum. 58, 2279 (1987); http://dx.doi.org/10.1063/1.1139336 (5 pages) | Cited 8 times

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A new method for the measurement of gas adsorption at high pressure is described in detail. The method is based on dielectric virial coefficients and it takes advantage of the dielectric technique for the accurate measurement of the compressibility factor of gases at high pressure. The method is simple, self‐sufficient, easy to use, and permits precise measurement of the density of nonideal gases. Adsorption measurements of methane on BPL‐activated carbon as a function of pressure at 25 °C are reported.
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82.80.-d Chemical analysis and related physical methods of analysis
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Ultrahigh‐vacuum system for surface studies using high‐energy ion scattering and x‐ray photoemission spectroscopy

R. J. Smith, C. N. Whang, Xu Mingde, M. Worthington, C. Hennessy, M. Kim, and N. Holland

Rev. Sci. Instrum. 58, 2284 (1987); http://dx.doi.org/10.1063/1.1139337 (4 pages) | Cited 16 times

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We describe a new ultrahigh‐vacuum facility which is being used for studies of solid surfaces. The target chamber is attached via a differentially pumped beamline to a 2‐MV Van de Graaff accelerator, and includes: (1) instrumentation for high‐energy ion backscattering and channeling studies and nuclear reaction analysis, (2) a 100‐mm radius hemispherical analyzer for photoemission studies, and (3) low‐energy electron diffraction (LEED) optics.
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07.30.Hd Vacuum testing methods; leak detectors
79.20.-m Impact phenomena (including electron spectra and sputtering)
79.60.-i Photoemission and photoelectron spectra

Very high‐vacuum heat treatment facility

W. M. Folkner, M. V. Moody, and J.‐P. Richard

Rev. Sci. Instrum. 58, 2288 (1987); http://dx.doi.org/10.1063/1.1139338 (4 pages) | Cited 2 times

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We have designed and constructed a vacuum heat treatment facility, with hot zone dimensions of 12×19×19 cm, at a cost substantially below that of a commercial unit. The design incorporates efficient water cooling and a resistive heating element. A vacuum pressure of 1.5×10−8 Torr at room temperature has been obtained after baking. The temperature limit is approximately 1900 °C. This limit results from our choice of niobium as the hot zone material.
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07.20.Ka High-temperature instrumentation; pyrometers
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
07.30.Hd Vacuum testing methods; leak detectors

Novel high‐pressure isolation cell capable of reaching 120 atm mounted in an ultrahigh‐vacuum chamber

T. G. Rucker, K. Franck, D. Colomb, M. A. Logan, and G. A. Somorjai

Rev. Sci. Instrum. 58, 2292 (1987); http://dx.doi.org/10.1063/1.1139339 (3 pages) | Cited 7 times

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A high‐pressure cell and manipulator mounted inside an UHV surface analysis chamber has been built which can reach 1800 psi. With this apparatus, catalytic reactions on small surface area (∼1 cm2) single crystals and polycrystalline surfaces are monitored, and the effect of reactant pressure, surface composition, and surface structure are correlated with catalytic activity. This article describes in detail the apparatus and typical experimental procedure.
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06.60.Sx Positioning and alignment; manipulating, remote handling
06.60.Ei Sample preparation (including design of sample holders)
82.80.-d Chemical analysis and related physical methods of analysis

Combination closed‐cycle refrigerator/liquid‐He4 cryostat for e− damage of bulk samples

E. C. Johnson

Rev. Sci. Instrum. 58, 2295 (1987); http://dx.doi.org/10.1063/1.1139340 (3 pages) | Cited 4 times

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A closed‐cycle refrigerator/cryostat system for use in ultrasonic studies of electron irradiation damaged bulk specimens is described. The closed‐cycle refrigerator provides a convenient means for long‐term (several days) sample irradiation at low temperatures. A neon filled ‘‘thermal diode’’ is employed to permit efficient cooling, via liquid helium, of the sample below the base temperature of the refrigerator.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
61.80.Fe Electron and positron radiation effects

Delay line anodes for microchannel‐plate spectrometers

M. Lampton, O. Siegmund, and R. Raffanti

Rev. Sci. Instrum. 58, 2298 (1987); http://dx.doi.org/10.1063/1.1139341 (8 pages) | Cited 44 times

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We describe a photon‐counting readout system for microchannel‐plate spectrometers that uses a delay line and timing circuit for the wavelength coordinate and a wedge–wedge charge division system for the orthogonal spatial coordinate. A novel zigzag layout allows these two anode patterns to coexist on a common planar substrate and share the charge from each photoevent, thereby simultaneously localizing the photon in each of its two dimensions. Unlike wedge‐and‐strip or resistive anode encoders, the delay line offers a spatial resolution that is relatively independent of the format length. Unlike discrete anode systems, the delay line readout system’s complexity is also independent of the field of view size. These facts make the delay line readout system advantageous in large format detectors. We have assembled a testbed detector having a delay line propagation speed of 2.2 mm/ns and a time resolution of 33 ps FWHM. Ultraviolet testing shows a Gaussian event distribution having a 70 μm FWHM width; the readout system blur contribution is less than 50 μm FWHM.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Rd Visible and ultraviolet spectrometers
07.50.-e Electrical and electronic instruments and components

Improved oscillating buoy viscometer

Rogers C. Ritter and Janelle A. Molloy

Rev. Sci. Instrum. 58, 2306 (1987); http://dx.doi.org/10.1063/1.1139342 (7 pages) | Cited 4 times

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An improved design of the vertically oscillating buoy viscometer with real‐time computer control, evaluation, and plotting is presented. In this method, the optically observed phase lag of the buoy relative to a sinusoidal driving force is a direct and absolute measure of viscosity. Construction features of the new version improve reassembly precision and give three‐axis positioning of the sphere, as well as an 80‐fold improvement in the signal‐to‐noise ratio for small amplitudes of the buoy motion. Design of the ‘‘crossed coil’’ system is discussed and the magnetic and mechanical faults which lead to various kinds of motional instability are considered. Boundary layer corrections are now computer corrected as are temperature variations. The evaluation of ‘‘intrinsic viscosity’’ as a measure of molecular ellipticity is discussed and one measurement set is presented.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
66.20.-d Viscosity of liquids; diffusive momentum transport

Apparatus for programmed high‐performance purification of surfactant solutions

K. Lunkenheimer, H.‐J. Pergande, and H. Krüger

Rev. Sci. Instrum. 58, 2313 (1987); http://dx.doi.org/10.1063/1.1139343 (4 pages) | Cited 29 times

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Generally, surfactants contain trace impurities that will falsify their adsorption properties enormously. To carry out reliable experiments with surfactant solutions necessitates removing those trace impurities beforehand. A programmed apparatus for removing surface‐active trace impurities from surfactant solutions has been constructed and tested. It takes advantage of the contaminants’ stronger surface activity and considerably lower content in comparison with the main surfactant component. Surface‐active material of the solution to be purified is allowed to adsorb at its surface. After considerable reduction of the solution surface area, the adsorbed material is sucked off from the surface in a definite manner by using a fine capillary. The single operating steps are repeated periodically and automatically until the solution reaches the state of ‘‘surface chemical purity.’’ The apparatus can be utilized for a wide range of different conditions given by the individual surfactant properties simply by changing the operating parameters. The instrument favorably and effectively provides that peculiar grade of surfactant purity necessary for all kinds of fundamental surfactant research and characterization.
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06.60.Ei Sample preparation (including design of sample holders)
82.80.-d Chemical analysis and related physical methods of analysis
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Design of electromagnetic devices using commercial finite element programs

M. Johnson, R. Wands, and E. Wolin

Rev. Sci. Instrum. 58, 2317 (1987); http://dx.doi.org/10.1063/1.1139344 (7 pages)

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The two‐dimensional electrostatic modeling capability of the ANSYS finite element program is used in the design of the coax‐to‐parallel plate microwave transformer. Its two‐dimensional axisymmetric capability is used in the design of a laser‐triggered coaxial Blumlein spark gap. Finally, its three‐dimensional magnetic modeling ability is used to model a large dipole magnet (the Chicago cyclotron magnet). The results of the calculations compare well with measurements for two of the above cases.
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02.70.-c Computational techniques; simulations
03.50.De Classical electromagnetism, Maxwell equations
45.05.+x General theory of classical mechanics of discrete systems
03.50.-z Classical field theories

Microprocessor‐based data‐acquisition system

Charles I. Umeagukwu, Walter H. Peters, and John R. Dickerson

Rev. Sci. Instrum. 58, 2324 (1987); http://dx.doi.org/10.1063/1.1139345 (7 pages) | Cited 1 time

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This article describes the development of an automated microprocessor‐based data‐acquisition system and, in particular, the use of an inexpensive microcomputer to automate an acoustic experiment. Specifically, it explains the use of a Motorola MC6801 in the single‐chip mode to control a rather complex experimental process. The system is configured to provide for automated, two‐dimensional data acquisition of ultrasonic transmissibility through a specimen surface. Results to evaluate the accuracy and the performance of the system with known analytical predictions will be presented.
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07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation
07.05.Bx Computer systems: hardware, operating systems, computer languages, and utilities
07.07.Mp Transducers
43.58.Ta Computers and computer programs in acoustics

Channel electron multiplier compatibility with Viton and Apiezon‐L vacuum grease

D. J. McComas, J. R. Baldonado, S. J. Bame, and B. L. Barraclough

Rev. Sci. Instrum. 58, 2331 (1987); http://dx.doi.org/10.1063/1.1139346 (2 pages) | Cited 6 times

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Clean Viton and Viton coated with Apiezon‐L vacuum grease were tested for their noncontaminating compatibility with channel electron multipliers (CEMs). The test setup and procedure were the same as those used previously in conjunction with CEM compatibility tests of certain epoxies, solder, and fluorocarbon polymer materials useful for construction of spaceflight sensors. While some CEM gain degradation was noted during exposure to Viton and Apiezon‐L, the present tests indicate that, at least over instrument lifetimes of ∼2×1012 counts, these materials should be suitable for (1) preflight space sensor testing systems, (2) hermetic seals for CEM‐based space sensors, and (3) terrestrial CEM‐based instrumentation.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
06.60.Vz Workshop procedures (welding, machining, lubrication, bearings, etc.)
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Rotating sample holder for ESR studies of relatively high conductivity, thin samples

V. G. Zarifis

Rev. Sci. Instrum. 58, 2332 (1987); http://dx.doi.org/10.1063/1.1139347 (3 pages) | Cited 1 time

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We have designed a low‐loss dielectric sample holder for positioning very thin, metallic, semiconductor samples in a TE102 cavity for ESR studies at liquid‐helium temperatures. The sample holder can be rotated ±15° from the center position, allowing accurate positioning of the high‐conductivity sample at minimum electric field. This results in maximizing the Q factor and allowing symmetric excitation on both faces of the sample. We have also devised a method of setting the microwave phase to desired value to better than 0.3° by utilizing the hyperfine lines of a dilute As‐doped Si sample.
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06.60.Sx Positioning and alignment; manipulating, remote handling
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
06.60.Ei Sample preparation (including design of sample holders)

Low‐noise ac/dc voltage source with continuous zero crossing

S. T. Ruggiero and J. B. Barner

Rev. Sci. Instrum. 58, 2334 (1987); http://dx.doi.org/10.1063/1.1139348 (2 pages) | Cited 1 time

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We have developed an active voltage source with low‐noise characteristics. The circuit was designed to drive components at constant voltage which are sensitive to extrinsic noise and power‐supply zero‐crossing transients.
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84.30.Jc Power electronics; power supply circuits

Simplified pipe gun

H. Sørensen, A. Nordskov, B. Sass, and T. Visler

Rev. Sci. Instrum. 58, 2336 (1987); http://dx.doi.org/10.1063/1.1139349 (2 pages) | Cited 4 times

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A simplified version of a deuterium pellet gun based on the pipe gun principle is described. The pipe gun is made from a continuous tube of stainless steel and gas is fed in from the muzzle end only. It is indicated that the pellet length is determined by the temperature gradient along the barrel right outside the freezing cell. Velocities of around 1000 m/s with a scatter of ±2% are obtained with a propellant gas pressure of 40 bar.
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28.52.-s Fusion reactors
52.55.-s Magnetic confinement and equilibrium
52.75.-d Plasma devices

Simple scheme for variable high‐power laser beam attenuation

Stephen E. Bialkowski

Rev. Sci. Instrum. 58, 2338 (1987); http://dx.doi.org/10.1063/1.1139651 (2 pages) | Cited 3 times

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A venetian style infrared attenuator placed prior to a pinhole spatial filter results in variable high‐power laser attenuation. This attenuation scheme has a wide dynamic range, results in high‐quality Gaussian beams, does not introduce beam walk‐off error, and is independent of polarization.
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42.79.Ci Filters, zone plates, and polarizers
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
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