bluuebunny/crossref_metadata_2025 huggingface dataset:
Sealed electrode configuration for gaseous plasmas
Authors: Kuehn D. G. , Smulders J. , Chanin L. M.
Published: March 2003

Described is an electrode configuration for gaseous plasmas in which Pyrex glass sheathes all but the interior of a hollow cathode. The inner surface is tailored to specific applications through the use of metal foils.
Closed-cycle cryogenic pump suitable for sounding rockets use
Authors: Erdman P. W. , Zipf E. C.
Published: March 2003

We have successfully used a closed-cycle cryogenic cooling system as a high-speed UHV pump for instruments carried into the upper atmosphere on board sounding rockets. The device utilizes a commercially available, Sterling-cycle refrigerator that has proven to be rugged and simple to use under field conditions.
Limited aperture light source streak photography
Authors: Vassiliou M. S. , Ahrens Thomas J.
Published: March 2003

In shock wave equation-of-state experiments employing inclined mirror techniques, limited aperture light sources such as the xenon flash lamp are generally more convenient to use than extended light sources employing explosives, but can create alignment problems when mirror inclination angles are large. These problems can be solved by employing a wedge-shaped inclined mirror in place of a flat one.
Silver halide film as a linear detector for 10.6 μm radiation
Authors: Mitchel G. R.
Published: March 2003

A two-step process is used to record middle infrared radiation on silver halide film for energy densities of <100 mJ/cm2 in a nanosecond pulse. This process uses the infrared light to sensitize the film to subsequent visible exposure. At such low infrared energy densities, a linear density increment above background is obtained.
Simple method for accurate ray tracing in electrostatic lenses
Authors: Kisker Erhard
Published: March 2003

A short basic program for calculating electron and ion trajectories in multiple-element tube lenses within the Gaussian approximation is presented. The program runs on personal computers with high accuracy.
Small computer-based system for determination of second- and third-order optical nonlinearities
Authors: Meredith Gerald R.
Published: March 2003

An apparatus is described which has been designed for the purpose of measuring second- and third-order nonlinear optical susceptibilities of electronic character. The optical power derives from a Q-switched Nd3+/YAG laser which through a variety of frequency converters allows thorough characterization in the spectral window between the high vibrational states in the near infrared and the low electronic transitions in the visible or near UV. Data collection, treatment, and analysis are performed by a small computer/controller. As example of the potentiality of the apparatus the observation of multiple cascading in summation third-order wave mixing by crystalline quartz is reported.
Chromatic aberration electron monochromator
Authors: Grisenti R. , Zecca A.
Published: March 2003

The performance of an electron monochromator based on the chromatic aberration of electrostatic lenses was investigated. A first approximation analysis of the monochromator’s operation is given. A prototype monochromator was built and tested to produce an electron beam of less than 25 MeV FWHM at 10−9A, with high stability and reproducibility. Design and operating details are given.
High-power neutral deuterium beam species measurement by neutralizer fusion product analysis
Authors: Smith R. R. , Strathman M. D.
Published: March 2003

Energy spectra of charged fusion products produced by 105-keV deuterium ions in a deuterium gas target are measured and used to infer the proportions of full, half, and one-third energy deuterons extracted from the accelerator.
Electron cooling in magnetic multipole arc discharges
Authors: Holmes A. J. T.
Published: March 2003

Internal magnetic structures or filters, which enhance the proton yield in magnetic multipole sources, also modify the electron temperature near the ion extraction electrodes. Results are presented for an electromagnetic filter which reduces the electron temperature by up to a factor of four. These measurements are in close agreement with a theoretical model based on the classical diffusion of particles and energy through the magnetic field of the filter.
High-impedance capacitive divider probe for potential measurements in plasmas
Authors: Benjamin Neil
Published: March 2003

It is often desirable, though difficult, to measure electric potential changes within a plasma, including variations due to waves and fluctuations. For a broad range of plasma parameters ac floating potential measurements may be made using the high input impedance probe described in this paper. A capacitive divider with an active buffer circuit is incorporated, such that a 50-Ω line can be driven with a 60-dB dynamic range and 100-MHz bandwidth. Details of the electronic circuit, mechanical construction, and calibration of the probe are given, together with a discussion of the parameter range over which successful measurements may be made.
Generation of synchronous, continuously tunable high-power picosecond pulses
Authors: Driscoll T. A. , Guidotti D. , Gerritsen H. J.
Published: March 2003

A system of synchronously pumped dye lasers is described that can produce 2 MW, nearly transform limited pulses of 15 ps duration. The two lasers are independently tunable between 550 and 710 nm with a bandwidth of 2 cm−1.
Dual polarization quasi-optical beam divider and its application to a millimeter wave diplexer
Authors: Payne J. M. , Davis J. E. , Hagstrom M. B.
Published: March 2003

A dual-polarization wire grid beam divider has been developed. This beam divider features simultaneous uniaxial dual-polarization operation, broad instantaneous coupling bandwidth, beam wave front preservation, and ease of fabrication. This paper describes a beam divider for 95 GHz, gives construction details, and presents a dual-polarization local oscillator injection diplexer as a typical example of a beam divider application.
Improved spectrometer for cathodoluminescence studies in scanning electron microscopy
Authors: Beauvineau J. , Semo J.
Published: March 2003

Some problems raised by studying defects in direct band-gap semiconductors can be solved with the help of spectral cathodoluminescence in scanning electron microscopy. This led us to build a spectrometer fitted to a SEM. A fully catadioptric optical system maintains achromatism over the whole spectral range and four blazed gratings allow wavelength dispersion between 0.2 and 3.0 μm with a wavelength resolution of the order of 5 nm. The detection unit, depending on the emitted radiations, is quite easily interchangeable.
Magnetically focused line source electron gun
Authors: Avida R. , Yeheskel J. , Friedman M. , Gazit D. , Levron D.
Published: March 2003

A magnetically focused line source electron gun for selective heat treatment of surfaces is described. A model calculation consisting of an electric field computation routine and a trajectory tracing procedure was performed. An electron gun, corresponding to the model, was built and tested and its characteristics measured. The gun delivered 10 kw/cm2 on a strip of 80×2 mm, which could be scanned over a range of 100 mm in a direction perpendicular to the long dimension of the strip, so that an area of 80×100 mm could be heat treated in a short time of the order of milliseconds. The magnetic focusing provides for uniform electron energy and beam density throughout the scanned area.
Alpha particle collimator for micron-sized beam
Authors: Henley F. J. , Oldham W. G.
Published: March 2003

A collimated alpha source is constructed from a drawn glass microcapillary and a plated polonium wire source. The shape of the capillary is approximately Gaussian, allowing an analytical model for the collimated flux intensity. The very gradual taper results in a nearly monochromatic beam. Two models are presented characterizing the particle flux intensity and its profile on a surface below the collimator tip. These models are experimentally verified using spectroscopy and isolated node mapping. Collimators having tip radii ranging from 5 to 25 μ have been successfully drawn and tested.
Characterization of shock and reaction fronts in detonations
Authors: Tulis Allen J. , Selman J. Robert
Published: March 2003

An instrumental technique has been developed which allows the concomitant measurement of the arrival times of both shock and reaction (flame) fronts in propagating detonations. A combination of fiber-optic probes and light detectors is used to monitor the arrival of the reaction front, whereas piezoelectric pressure gauges monitor the arrival of the pressure pulse from the preceding shock wave. Both signals provide the measurement of the detonation velocity; variance between shock and reaction front velocities implies nonstable detonation (growing or dying detonation) which can be attributed to variation in density, concentration, or homogeneity of the detonating media. This technique is straightforward in the case of pressed or cast formulations but presents difficulties when gas-phase or two-phase detonations are involved. The detonation of near-stoichiometric ethylene–air mixtures in a detonation-tube facility was used to refine the technique and calibrate the instrumentation. The technique was then used to characterize the detonation of two-phase aluminum powder–air mixtures of various concentrations. Compared to the 3-μs induction time between the shock and reaction fronts in the case of ethylene–air mixtures, the induction times for aluminum powder–air mixtures varied from about 1 to over 100 μs. The variation in induction time was attributed to several factors: extended heating time to ignition of the particles due to inhomogeneity of the two-phase mixtures; variation in particle size; and variable aluminum-oxide surface coating thickness. The concentration of aluminum powder in the air was monitored dynamically using instrumentation that related the concentration of aluminum to the attenuation of a laser beam through the mixture. A mean, or overall, value was also estimated by determining the mass flow rate and overall discharge time using photographic coverage. In the former case, in order to obtain meaningful signals for these high-concentration two-phase systems it was necessary to reduce the pathlength of the laser beam through the mixture to a small fraction of the total width of the tube. Hence, the observed concentration measurements did not necessarily reflect good homogeneity across the width of the tube. Nevertheless, with some modifications this technique can be exceptionally useful for this most difficult measurement.
Precision operational-amplifier mutual inductance bridge for cryogenic thermometry and susceptibility measurements
Authors: Corson M. R.
Published: March 2003

A mutual inductance bridge is described which employs operational amplifiers and a Kelvin–Varley divider in a configuration providing high precision and low noise. The linearity and stability of the bridge are approximately 10 ppm for the reactive part of the unknown mutual inductance in the frequency range 10–300 Hz. The noise is approximately 15 nV/√Hz. The bridge, built from readily available or constructed components, is suitable for cryogenic thermometry and ac susceptibility measurements.
Reliable and simple method to measure relative changes of sound velocity automatically
Authors: Bamberg J. , Schmitt H. , Arnold W.
Published: March 2003

A method is described which allows one to measure, automatically, relative velocity changes as a function of an external parameter. The method utilizes standard electronic equipment and is based on pulse-echo tracking by a sampling oscilloscope and an integrating amplifier. Its fast response time facilitates monitoring rapid velocity changes as occurring, for example, during the poling process of ferroelectric ceramics or at phase transitions, and relative velocity changes of the order of 10−5 can be detected easily.
Computer controlled digital planimeter
Authors: Blackburn James A.
Published: March 2003

An automatic digital planimeter is described. The system consists of a desktop computer, digital plotter, and high-resolution reflectance sensor. It operates on simply connected curves by first scanning and digitizing the figure, and then carrying out a numerical integration on the stored data. A test case confirms that the area evaluations are quite accurate.
Microcomputer-controlled fabrication of mirrors and lenses for far-infrared and submillimeter applications
Authors: DuVarney R. C. , Puckett O. H.
Published: March 2003

At a relatively low cost, a standard lathe was equipped and interfaced for microcomputer control for use in the fabrication of mirrors and lenses for far-infrared and submillimeter applications.
Bubble-free encapsulation of magnetic probes for use in a high-voltage plasma discharge
Authors: Deniz Alban , Merlino Robert L.
Published: March 2003

A procedure is described for effecting a bubble-free encapsulation of a magnetic probe for use in a high-voltage plasma discharge.
Easily constructed high-vacuum valve
Authors: Gilbert S. L. , Wieman C. E.
Published: March 2003

We present a design for a high-vacuum valve which can be built very quickly and easily. It has the additional feature that it is very thin.
Level based on moiré deflectometry
Authors: Livnat A. , Kafri O.
Published: March 2003

We demonstrate an optical level based on the measurement of the inclination angle between a mirror and a reference liquid surface by moiré deflectometry. It may be operated with noncoherent light under conditions of relatively low mechanical stability.
Closed-cycle refrigerator solution cell for low-temperature optical spectroscopy
Authors: Carter T. P. , Gillispie G. D.
Published: March 2003

The design and construction of a solution cell for low-temperature optical spectroscopy with a closed-cycle refrigerator is discussed.
Scanning delay generator for measurement of kinetic decays using laser-induced fluorescence techniques
Authors: Halpern Joshua B. , Towns Theodore G.
Published: March 2003

An electronic device is described which generates a delayed pulse, where the delay is increased in a step-like manner. This device finds application in the measurement of kinetic decays, particularly when laser-induced fluorescent (LIF) detection of the decaying species is used. The circuit uses 15 low-power Schottky TTL chips and is contained within a dual width NIM module.
Optical pumping of He(23S) atoms by a color-center laser
Authors: Giberson K. W. , Cheng Chu , Onellion M. , Dunning F. B. , Walters G. K.
Published: March 2003

A color-center laser operating at 1.08 μm has been used to optically pump a thermal He(23S) atom beam via 23S→23P transitions. Even modest laser powers (∼10 mW) result in more efficient optical pumping than is obtained using a 400-W rf-excited helium resonance lamp. The laser also permits optical pumping via transitions to selected 23P fine structure levels.
Reproducible triggering of a vacuum spark
Authors: Fong K. , Ng A. , Barnard A. J.
Published: March 2003

The reproducibility of a vacuum spark discharge has been improved by plasma injection triggering, in which the discharge is initiated by the injection of plasmas formed from a triggering electrode. With this triggering method, the first Z pinch of the discharge occurs reproducibly with a jitter of only 50 ns.
Frequency-modulated coil sensor for magnetic suspensions
Authors: Bernard Bruce E. , Cheung W. Stephen , Ritter Rogers C.
Published: March 2003

A FM coil sensor using digital electronics is described here for use as a position transducer in a magnetic suspension. This is similar to the Q-coil method of Beams et al. [Rev. Sci. Instrum. 33, 151 (1962)] as used in magnetic suspensions except that a different parameter is being controlled. The circuits are presented and their operating characteristics are discussed.
S−100/Z80 microprocessor-based scanning microdensitometer and signal processing system
Authors: Sala K. L. , LeSage R. , Yip R. W.
Published: March 2003

A S-100/Z80 8-bit microprocessor-based system which is used to digitize, reduce, and smooth picosecond data is described. Utilizing real-time signal sampling combined with a software-controlled signal averaging, the system uses, to the maximum extent, all of the information obtainable from the microdensitometer. The versatility of the system, in terms of both the hardware and software, minimized the need for extensive in-house interfacing and makes it possible to scan a film containing six spectra (6×40K raw data points) in 16 min. The use of a LS1 stepping motor controller chip is described.
Low-energy neutral atom spectrometer
Authors: Voss D. E. , Cohen S. A.
Published: March 2003

The design, calibration, and performance of a low-energy neutral atom spectrometer are described. Time-of-flight analysis is used to measure the energy spectrum of charge-exchange deuterium atoms emitted from the PLT tokamak plasma in the energy range from 20 to 1000 eV. The neutral outflux is gated on a 1-μs time scale by a slotted rotating chopper disc, supported against gravity in vacuum by magnetic levitation, and is detected by secondary electron emission from a Cu–Be plate. The energy dependent detection efficiency has been measured in particle beam experiments and on the tokamak so that the diagnostic is absolutely calibrated, allowing quantitative particle fluxes to be determined with 200-μs time resolution. In addition to its present application as a plasma diagnostic, the instrument is capable of making a wide variety of measurements relevant to atomic and surface physics.
Supersonic nozzle beam source of atomic oxygen produced by electric discharge heating
Authors: Silver J. A. , Freedman A. , Kolb C. E. , Rahbee A. , Dolan C. P.
Published: March 2003

An atmospheric pressure supersonic nozzle beam source of atomic oxygen is described. Dissociation of molecular oxygen is accomplished by injection into a flow of helium and/or argon which has been heated in a commercial plasma torch. Dissociation efficiencies approaching unity are achieved with beam velocities in the range of 1.5–4.0 km s−1. Production of rare gas metastable and electronically excited oxygen species are minimized by the source design.
Infrared laser spectroscopy of molecular beams using a room-temperature beam detector: Application to the study of translational freezing in free-jet expansions
Authors: Miller R. E.
Published: March 2003

A simple and inexpensive alternative to the liquid He bolometer for observing laser induced vibrational excitation in molecular beams is reported. A room-temperature pyroelectric detector is used to directly measure the increase in molecular energy resulting from laser excitation. With this detector, line broadening effects have been used to study translational freezing in free-jet expansions.
Method for measuring specific heats in intense magnetic fields at low temperatures using capacitance thermometry
Authors: Lawless W. N. , Clark C. F. , Arenz R. W.
Published: March 2003

A drift method is described for measuring specific heats in intense magnetic fields at low temperatures. Capacitance thermometry is used, and an automated data-collection system utilizes the imbalance of a transformer-ratio-arm bridge to process the capacitance data. The zero-field specific heat must be known, and measurement of the in situ drift in zero-field calibrates the thermal link. Additional calibration of the link is required if the link’s magnetothermal conductivity effects are significant, and a specific example of a copper-wire link is presented. The method resolves complex structure in the specific heat near a steep λ-type anomaly, as illustrated by measurements on a chromite spinel at 7.5 T. The uncertainty in the method is estimated to be ≂±7%.
Electrical properties of an input–output cable for Josephson applications
Authors: Anderson C. J.
Published: March 2003

The electrical properties of an 80 signal line microstrip cable for transmitting signals between room-temperature electronics and cryogenic electronics were calculated and verified. The impedance, propagation velocity, skin effect losses, dielectric losses, forward wave cross talk, and backward wave cross talk were investigated for a copper and polyimide microstrip cable. An effective method of reducing forward wave cross talk was discovered. The microstrip cable has a high signal line density, 19.7 lines/cm, and a high bandwidth, dc-1 GHz.
High repetition rate mini TEA CO2 laser using a semiconductor preionizer
Authors: Rickwood K. R. , McInnes J.
Published: March 2003

A mini TEA CO2 laser using a semiconductor preionizer is described. The laser will operate at a pulse repetition frequency greater than 5 kHz. At a pulse repetition frequency of 1 kHz a mean power output of 35 W can be maintained over extended periods. Burst mode operation of 104 shots at a pulse repetition frequency of 1.5 kHz can produce mean power in excess of 50 W.
Fast transient digitizer system using a TV camera for the measurement of optically induced spin polarization
Authors: Takagi Y.
Published: March 2003

A fast digitizer for single transient analysis is described which is composed of a microcomputer-based image processor and a TV camera attached to a 1-GHz oscilloscope. Oscilloscope traces are viewed by a TV camera and displayed on a TV screen in a digitized form. The corrected data can be accumulated at 1.5 s intervals. The system has been used successfully for measurements of nanosecond single transients in a study of optically induced spin polarization. Hardware design, software, and experimental performance are described.
High-pressure–low-temperature apparatus for NMR study of phase transitions
Authors: Schuele Paul J. , Schmidt V. Hugo
Published: March 2003

An apparatus has been developed for nuclear-magnetic-resonance (NMR) measurement of relaxation times in solids at hydrostatic pressures to 7 kbar and temperatures down to 77 K. Sample temperature can be controlled accurately with ±2 mK stability allowing measurement of dynamic phenomena very near phase transitions. The high-pressure vessel is equipped with additional electrical feedthroughs so that dielectric measurements can be carried out concurrently, providing additional information on ferroelectric phase transitions.
Balanced cavity scheme for saturation transfer dispersion electron paramagnetic resonance
Authors: Anderson James R. , Mailer Colin
Published: March 2003

Dispersion electron paramagnetic resonance (EPR) suffers from high AM noise levels due to discrimination of FM noise from the klystron by the high Q cavity. If the EPR cavity is placed in one arm of a magic tee, and a similar cavity in the other arm, then this noise can be removed by arranging the two (correlated) noise components to cancel. Signal-to-noise ratio improvements of a factor of 40 are easily attainable. Only minor modifications to commercial instruments are required.
Automatic capacitance–voltage (C–V) plotter for solar cells
Authors: Purshotham M. , Das S. R. , Mukerjee A. K. , Chopra K. L.
Published: March 2003

An instrument is described which measures the capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of solar cells in the dark and under illumination and other semiconductor junction devices in the capacitance range of 2–200 000 pF. The instrument is also provided with the facility for DLTS measurements.
Design and operation of a self-calibrated thermistor plasma calorimeter
Authors: Simpson J. D.
Published: March 2003

This report describes the design and operation of a new diagnostic instrument for measuring the conversion of laser energy into plasma ions and soft x rays during ICF laser-target interaction experiments. The instrument is operated as a differential calorimeter, and uses low mass thermistor flakes as both energy transducers and calibration sources. The calorimeter provides its own running energy calibration, in situ, by inducing electrical self-heating of the thermistor elements. The instrument can be calibrated over a range of energies, either automatically or by manual selection. Calibration and operating principles are discussed, as well as physical and electronic design considerations, measurement and calibration data, and error sources.
Ballistic pendula for measuring the momentum of a laser-produced plasma
Authors: Grun J. , Ripin B. H.
Published: March 2003

We describe the use of a ballistic pendulum array to measure the momentum of a laser-produced plasma. An in situ calibration method is described and the pendulum results are compared to measurements made with other diagnostics.
Improved instrumentation to carry out surface analysis and to monitor chemical surface reactions in situ on small area catalysts over a wide pressure range (10−8–105 Torr)
Authors: Cabrera A. L. , Spencer N. D. , Kozak E. , Davies P. W. , Somorjai G. A.
Published: March 2003

Improved one-tier and two-tier designs for a high-pressure–low-pressure (HPLP) apparatus are described together with some of their recent applications. These instruments are used for surface analysis and in situ monitoring of catalytic reactions on small samples with a geometrical surface area of 1 cm2. Catalytic reactions are studied over a wide range of pressures (10−8–105 Torr) and temperatures (273–1273 K). The apparatus incorporates surface analysis methods such as Electron Spectroscopy for Chemical Analysis (ESCA), High Resolution Electron Energy Loss Spectrometry (HREELS), and 14C-radiotracer labeling in addition to Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), and mass spectrometry. Facilities are also available for argon sputter-ion cleaning, deposition of adsorbates by evaporation, and coverage calibration by means of a thickness monitor.
Local area time dissemination by carrier-current waves
Authors: Mureddu L. , Pegna G. G.
Published: March 2003

Carrier-current waves (CCW) on ac power lines have been used to build up a new type of transmission network for timing signals. The peculiarities of the information carrier characterize its behavior as a standard frequency relay. Already existing very low-frequency (VLF) timing receivers and constructed ad hoc transmitters have been used. Results reported here of tests carried out over extended time periods show that high precision and reliability are obtainable.
Modification of a commerical NOx detector for high sensitivity
Authors: Delany A. C. , Dickerson R. R. , Melchior F. L. , Wartburg A. F.
Published: March 2003

We describe modifications of a commercial chemiluminescent NOx detector to provide sufficiently high sensitivity to measure oxides of nitrogen in clean continental air. The changes include a larger reaction chamber, a faster vacuum pump, and a prereactor for background measurement. The detection limit, defined as a signal-to-noise ratio of 1:1 at the 2σ level, is about 0.10 ppb, with a response time of about 3 s. This corresponds to a ten-fold improvement over the original detection limit.
Lightweight ozonizer for field and airborne use
Authors: Stone E. J. , Caldwell J. R. , de Waal C. , Horvath J. J. , Pearson R. , Stedman D. H.
Published: March 2003

An efficient, lightweight apparatus for the production of ozone in flowing oxygen or air has been constructed and tested. The exciter is an automotive electronic ignition running from a 28-V dc power source. The discharge tube consists of coaxial conductive-coated flint glass tubing fitting into Teflon end pieces. A single such unit will produce 4% ozone in oxygen flowing at 0.2 l/min, or a maximum of 0.020 l of ozone per minute in a total flow of 1.0 l/min.
Automatic apparatus for nucleation investigations
Authors: Baldwin Mark , Vonnegut Bernard
Published: March 2003

An automated apparatus serves repeatedly to detect and record the repeated formation of the crystalline phase in a single sample of a supercooled liquid. The technique is successfully applied to investigations of the nucleation of ice formation with silver iodide by repeatedly freezing and thawing a small volume of water in a U-shaped capillary tube.
Modified gauge for time-resolved skin-friction measurements
Authors: Ajagu Christopher O. , Libby Paul A. , LaRue John C.
Published: March 2003

A new gauge for skin-friction measurements in turbulent flows involving a wire close to the surface and a second, flush-mounted film which serves as a constant temperature guard heater is described and evaluated. It is shown that a laminar calibration of the gauge applies to measurements in turbulent flow and that the frequency response of the gauge is appropriate for time-resolved data in such a flow. Initial results from a turbulent channel flow are presented.
Nozzle design yielding interferometrically flat fluid jets for use in single-mode dye lasers
Authors: Härri Hans-Peter , Leutwyler Samuel , Schumacher Ernst
Published: March 2003

Fundamentals and design principles are presented for the generation of interferometrically flat jets of viscous fluids. The jet quality is optically analyzed and nozzle performance investigated in cw single-mode dye laser operation. A nozzle providing a dye jet with an optically flat area of 9 mm2 is described. It produces a single-mode bandwidth of ∼5 MHz without any active stabilization.
Simple arrangement for spatially scanning gain measurements in cw lasers
Authors: Massig Juergen H.
Published: March 2003

A scheme for spatially scanning gain measurements is presented. Here, the parallel shift of the probe laser beam is effected by a rotating assembly of two plane mirrors. The arrangement is inexpensive and easy to adjust. It was applied to measure spatial gain profiles of a cw DF laser.
Subnanosecond high-voltage 50-Ω calibrated attenuator
Authors: Bartolini L. , Fascetti M.
Published: March 2003

We describe a single stage 50-Ω, 10× resistive attenuator with a rise time less than 100 ps used to measure 20-kV, 2-ns pulses, driving an electro-optic shutter in a 50-J, CO2 laser system. An aqueous solution of aluminum nitrate is used as a resistive element. An axially symmetric shielded structure allows cascade operation of more units. Practical design parameters for a given matched impedance and attenuation as well as calibration procedures are reported.
Possible systematic error in molecular beam time-of-flight analysis with a quadrupole mass spectrometer
Authors: Siddiqui H. R. , Khan A. , Siska P. E.
Published: March 2003

Substantial error in estimating widths of supersonic molecular beam speed distributions can result when using a conventional quadrupole mass spectrometer in pulse-counting mode as a molecular beam detector. This results mainly from improper discriminator settings reached in attempting to maximize signal to background. The effect is illustrated with measurements on a nominally Mach-10 helium supersonic beam.
Simple powerful tunable single-mode and mode-locked TEA CO2 laser
Authors: Dougal R. A. , Gundersen M. A. , Williams P. F.
Published: March 2003

A simple method for constructing a single longitudinal-mode CO2 laser that is tunable within individual rotational transitions is presented. Useful power levels, typically 0.3 J per pulse in a single-mode beam, are obtained from a single-stage device. Mode-locked output can also be obtained from the laser. In addition, design and construction of a local oscillator for making absolute in situ frequency measurements is described.
Discharge energy loading characteristics of a UV-preionized TEA CO2 laser
Authors: Suzuki Shun-ichi , Ishibashi Yuko , Obara Minoru , Fujioka Tomoo
Published: March 2003

The effects of ultraviolet (UV) preionization energy and initial electron number density on discharge loading are experimentally clarified in a UV preionized TEA CO2 laser. Dependence of the laser output energy on the spatial uniformity of the preionization has also been examined. In order to produce the laser output energy efficiently, the input energy for the UV preionizer is required to be in excess of 2% of the input energy for the main discharge. With the sufficient initial electron number density, the laser energy was little dependent on the spatial nonuniformity of preionization in the discharge volume at low-energy loadings (≲ 100 J/l). At higher energy loadings, the laser output energy was found to depend not only on the initial electron number density but also on the spatial uniformity of the preionization.
Far infrared laser system for the measurement of collision-induced absorption spectra
Authors: Dagg I. R. , Read L. A. A. , Vanderkooy J.
Published: March 2003

A system for the measurement of collision-induced absorption using a CO2 optically pumped FIR laser is described. The report emphasizes the laser stabilization systems that have been developed, the design of the absorption cell, and the detection methods employed to obtain the required data. Also included are some typical results at 15.1 cm−1 for nitrogen, ethylene, carbon dioxide, and ethane gases.
Interferometric refractometer for measuring the relative refractive index of two liquids
Authors: Singer K. D. , Merlin M. S. , Lalama S. J. , Garito A. F.
Published: March 2003

An interferometric technique for directly measuring small differences in refractive index between two liquids of similar refractive index is described. The method is based on measuring the phase change on translation normal to the beam propagation in one arm of a Michelson interferometer of a compensating double wedge filled with the two liquids. Details of the sample cell, interferometer construction, signal detection, and experimental procedure are described. Resolution in refractive index difference of 10−6 has been obtained.
Point focusing x-ray camera and the study of total external reflection
Authors: Kurata Hisashi
Published: March 2003

The total external reflection coefficients of a glass and gold reflector for CuK radiation were determined experimentally, with results in good agreement with the theoretical calculation. Partial monochromatization of the reflected beam by the glass reflector was also verified experimentally. Based on this study, a point focusing x-ray camera with two bent (horizontal and vertical) reflectors was designed and made. The horizontal reflector uses a glass mirror, and the vertical reflector uses either a glass mirror or a monochromator. This camera can thus be used in either a mirror–mirror (Franks optics) or a mirror–monochromator configuration (Huxley–Holmes optics). By changing the vertical reflector, the configuration can be simply exchanged and the best use of the characteristics of the two available optics can be made. The choice of optics depends mainly upon the irradiated size of the specimen: the mirror–mirror optics gives narrow beams (3′–6′), and the mirror–monochromator optics gives convergent beams (1°–1.2°) and much greater intensity. Small-and wide-angle diffraction patterns are detected with variations of specimen to film distance. For diffraction angles smaller than about 1°, both cases require a fine focus source smaller than about 0.1×0.1 mm in projection to prevent the production of Kα1–Kα2 doubled diffraction pattern by the monochromator and a reduction of resolution due to the extent of the focusing point by the glass reflector.
Sciopticon array analysis of ORNL ion sources
Authors: Ryan P. M. , Whealton J. H. , Feezell R. R.
Published: March 2003

The neutral beam sciopticon (pinhole camera) has been expanded to an array of pinhole apertures in order to simplify the process of distinguishing between beam imperfections caused by extraction nonuniformities and those caused by beamlet missteering. An analysis scheme is presented whereby the power transmission loss due to beamlet missteering may be estimated if the average beamlet divergence anlge is known. For a well-focused ion source, the sciopticon array can also give the approximate beam focal length and average beamlet divergence angle. Results from testing five ORNL ion sources indicate that the principal mechanism for differences in power transmission is beamlet missteering.
Cesium supersonic jet for D− production by double electron capture
Authors: Bacal M. , Doucet H. J. , Labaune G. , Lamain H. , Jacquot C. , Verney S.
Published: March 2003

A steady-state, supersonic cesium jet generator has been developed for use in an intense negative deuterium ion source, based on double electron capture. The cesium target thickness is 2.5×1015 atoms/cm2 for an oven temperature of 600°C, with an average geometrical thickness of 3.0 cm. The cesium flux, determined from calorimetric measurements, is found to be in agreement with a simple calculation of supersonic flow through a slit.
Multichannel CO2-laser interferometer using a PbSnTe detector array
Authors: Hugenholtz C. A. J. , Meddens B. J. H.
Published: March 2003

A multichannel CO2-laser interferometer has been built to measure electron line-density profiles of plasmas. In the work path a sheet-like beam is transmitted over the total extension of the plasma, to be refocused onto a detector array, where interference with the reference beam occurs. In this way a ’’phase image’’ of the plasma is produced on the detector elements. With the data acquisition system used, it is possible to follow the development in time of the profiles.
Modified Millikan capacitor for photoemission studies
Authors: Altwegg L. , Pope M. , Arnold S. , Fowlkes Wm. Y. , El Hamamsy M. A.
Published: March 2003

A description is given of the modification made to the Millikan capacitor that renders it particularly suitable for precise photoemission measurements on individual particulates in controlled atmospheres. These measurements make it possible to use photoemission as a tool for the study of bimolecular processes.
Energetic ion mass spectrometer
Authors: Neugebauer M. , Clay D. R. , Goldstein B. E. , Goldstein R.
Published: March 2003

A new type of spectrometer for space application has been developed and tested in the laboratory which measures separately, mass/charge and the three-dimensional velocity distribution of incident ions. The instrument has relatively high resolution (m/Δm = 600 amu/m) and allows rapid measurement of the four-dimensional set: mass/charge, speed, elevation angle, and azimuth angle. The basic components include: (1) a sector magnet which serves as a momentum/charge filter with a very wide angular acceptance, (2) an electrostatic deflector which spreads the momentum-analyzed ion beam according to energy/charge (or mass/charge), (3) microchannel plate detectors with position sensitive readout, and (4) a set of grids with variable applied voltage to accelerate or decelerate the incident ions before they enter the analysis part of the instrument. For application in a comet environment an electrostatic mirror would be used to reflect ions into the instrument while preventing dust from entering the field of view.
Technique for generating focal-plane flattop laser-beam profiles
Authors: Veldkamp Wilfrid B.
Published: March 2003

A highly efficient technique for shaping laser-beam profiles has been developed. This technique can produce one- or two-dimensional approximate flattop profiles in the far-field and focal-plane domains. It uses a binary diffraction grating with a central π-phase reversal in the periodic relief structure. Grating periodicity and relief depth parameters determine the shape of the beam profile in the focal plane. Two configurations of the beam shaper, transmissive and reflective, have been tested with 10.6 μm, CO2, TEMoo mode lasers.
Intense square-flash source for time-resolved absorption spectroscopy
Authors: Paur Richard J. , Dorsett John L. , Bair Edward J.
Published: March 2003

This paper describes a compact xenon flash source and associated circuit designed as an absorption background source for time-resolved spectroscopic measurements. The output is a square wave of nearly constant intensity for a period of 250 μs. Its spectral emissivity is roughly equivalent to a blackbody of 12 000 K, depending on the voltage used, except for a cutoff in the far ultraviolet by the quartz envelope. The lamp jacket is simple and inexpensive to replace and refill.
Improved optical probe for monitoring dust explosions
Authors: Conti R. S. , Cashdollar K. L. , Liebman I.
Published: March 2003

An improved optical probe was developed to monitor dust-cloud concentration in explosions even in the presence of dust flame radiation. Principal features of the probe include a pulsed light-emitting diode and a photodetector with optical interference filter to reduce flame radiation. The probe has a U-shaped configuration and air jets to keep the windows dust free. Experimental data are presented for a coal dust explosion.
Mass adjuster for pressure balance
Authors: Smart P. W.
Published: March 2003

A device for changing the masses in a Bell and Howell gas operated piston gauge without breaking the vacuum is described. This saves time and minimizes the risk of contamination.
Direct-drive magnetic stirrer
Authors: Yang Chan-Lon , Su Tzu-Min
Published: March 2003

A simple analog circuit is described for a direct-drive stirrer for use with a dye laser. It has advantages of simplicity over a motor-driven stirrer and a digital circuit for direct drive.
Regulated heater and controller for safe, rapid warming of helium Dewars
Authors: Mueller R. M. , Ihas G. G. , Adams E. D.
Published: March 2003

A 120-W heater and its control circuit for the safe warming of a helium Dewar to room temperature are described. The controller senses the temperature of the heater by a thermistor attached to it and shuts the heater off when it is just above room temperature. In the case of a dangerous malfunction, a meltable link mounted on the heater opens the electrical circuit when the heater reaches 61 °C.
Fabrication of spiral filaments for multifilament ion sources
Authors: Persing H. M. , Conrad J. R. , Horne S. F. , Pirkle D. R.
Published: March 2003

A simple method for fabricating spiral filaments for multifilament ion sources is described.
ACT-I: A steady-state torus for basic plasma physics research
Authors: Wong K. L. , Ono M. , Wurden G. A.
Published: March 2003

The construction and operation of a steady-state toroidal plasma device are described. The toroidal plasma can be maintained without any rotational transform and the plasma quality is significantly better than that in linear devices. It opens up new areas for basic plasma physics research. Examples of experiments on wave propagation, heating, and current generation are presented.
Properties of an intense 50-kV neutral-beam injection system
Authors: Gardner W. L. , Barber G. C. , Blue C. W. , Dagenhart W. K. , Haselton H. H. , Kim J. , Menon M. M. , Ponte N. S. , Ryan P. M. , Schechter D. E. , Stirling W. L. , Tsai C. C. , Whealton J. H. , Wright R. E.
Published: March 2003

The properties of an intense 50-kV neutral-beam system are discussed. The salient features of this system are a transmission efficiency of 76% of the extracted ion beam through a 30×34 cm aperture that is 4.5 m from the ion source, a transmitted neutral power of 1.8 MW H0 (2.0 MW D0) at extraction parameters of 50 kV/100 A/0.1 s (53 kV/85 A/0.1 s), a proton fraction of ∼80%, an ion-source arc efficiency of ∼1.3 A/kW, an ion-source gas efficiency of ∼35%, and a reliability of ≳90%.
Dewar design for optically pumped semiconductor lasers
Authors: Roxlo C. B. , Salour M. M.
Published: March 2003

A liquid-nitrogen Dewar has been constructed to allow precise and stable alignment of semiconductor platelets. Laser action in an external cavity is observed when the platelets are longitudinally pumped by an Ar+ laser. A microscope objective mounted inside the Dewar is used to focus both the pump and the semiconductor laser beam to a 5-μm spot. The sample can be moved and tilted while being kept at a temperature of 85 K. Sample mounting techniques are also described.
Novel corrosion-resistant supersonic expansion cluster source
Authors: Kay Bruce D. , Lindeman T. G. , Castleman A. W.
Published: March 2003

A corrosion-resistant stagnation chamber and supersonic nozzle assembly has been developed. The performance of this device as a source of hydrogen-bonded clusters is reported.
Remotely controlled passive pulse-shaping device for subnanosecond duration voltage pulses with stepwise selectable pulse length
Authors: Luthjens L. H. , Vermeulen M. J. W. , Hom M. L.
Published: March 2003

Described in this paper is the construction, the electric selection circuit, and the performance of a remotely controlled device that produces subnanosecond duration pulses with fast rise and decay times with stepwise selectable pulse length. Coaxial line pieces with a short-circuited side branch of definite transmission length are inserted in a coaxial pulser output cable. The device can be used in combination with a 50-Ω coaxial line pulser for nanosecond pulses and pulse voltages up to several kilovolts. More than 1000 h of successful operation in the terminal of a Van de Graaff electron accelerator has proven its reliability.
Frequency-swept detector for ion cyclotron resonance mass spectrometers
Authors: Wronka J. , Ridge D. P.
Published: March 2003

Design, construction, performance, and use of a frequency-swept bridge detector for ion cyclotron resonance mass spectrometry are described. Special features include characterization and simple automatic correction of phase shift to allow broadband detection. The result is a detection system that may be used either at constant field or constant frequency. Drift-mode operation is simplified in that it may be satisfactorily used without the various signal modulation schemes used in previous detectors. In the trapped mode the detector may be pulsed to control the timing of ion detection. This detector makes it possible to do frequency-swept double resonance experiments which provide spectra of all the product ions of a given reactant ion. Circuit schematics and typical frequency- and field-swept spectra are shown.
High-temperature battery calorimeter
Authors: Hansen L. D. , Hart R. H. , Chen D. M. , Gibbard H. F.
Published: March 2003

A battery calorimeter was built for the measurement of thermal energy generation of high-temperature lithium–aluminum/iron sulfide battery cells, which are under development for electric vehicle propulsion and other energy storage applications. The calorimeter was designed with a temperature range of 400 °–500 °C, a detection limit of 1 mW, and an upper limit of heat flow of 50 W. The results of measurements on 200-Ah LiAl/FeS cells were in excellent agreement with the predictions of thermodynamic calculations based on precise measurements of the total cell polarization and the temperature coefficient of the emf. Details of the construction and operation principles of this calorimeter are given.
Stable wideband ac–dc converter
Authors: Kakimoto Akira , Ohshita Masahide
Published: March 2003

This paper describes improvements on a stable wideband ac–dc converter, which is basically composed of a dual junction field effect transistor and a low drift operational amplifier. This converter has a stable square-law transfer characteristic up to 200 MHz for 0–0.5 V output with a drift of less than 0.1 mV/h. Its input capacitance is 6–10 pF and input conductance is negligibly small. It can also be used as a well-balanced differential converter for two ac inputs. With the combination of several temperature compensation techniques, the temperature dependence of the output level is reduced to −0.1%/ °C.
CRISIS detector: Characteristics and performance
Authors: Shapiro A. M. , Alyea E. D. , Barreiro F. , Goloskie D. A. , Kistiakowsky V. , McManus J. B. , Stoughton T. B. , Wadsworth B. F , Wu Y. , Plano R. J. , Bugg W. M. , Kitagaki T. , Ludlam T. , Murphy O. E. , Steiner R. V. , Taft H. D.
Published: March 2003

A drift chamber, which makes possible the identification of charged particles in the momentum range 5–100 GeV/c by taking 192 samples of the ionization which they produce in 1.6 cm of 80% argon–20% CO2, has been constructed and tested. It is 1×1×3 m in the sampling direction and is operated at a pressure slightly above atmospheric. It has been found to be very stable in operation and to give an average resolution for the average charge distribution of 8.13±0.18% (FWHM) in agreement with the predicted value of 8.4%.