bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient conductivity measurements with subnanosecond time resolution
Authors: Beck G.
Published: March 2003

The parameters governing the response time of a system to follow transient changes of conductivity caused by short pulses of radiation are discussed, and designs for coaxial conductivity cells with parallel-plate electrodes to obtain subnanosecond time resolution are described. The performance of the system is evaluated using ionization pulses of 30-ps width. This yields values in agreement with theory: 95 ps for the rise time and 80 ps for the fall time with virtually no signal distortion. Ways to decrease these times further are discussed.
Differential capacitance sensor as position detector for a magnetic suspension densimeter
Authors: Frederick N. V. , Haynes W. M.
Published: March 2003

A differential capacitance sensor has been used in the servosystem of a magnetic suspension densimeter to detect the position of a magnetic buoy. This type of sensor has not previously been used in this application. Its design, performance, and advantages are described.
Rocket-borne instrumentation using the resonant absorption technique to study the geocoronal and interplanetary helium emissions
Authors: Crifo J. F. , Fahr H. J. , Seidi P. , Wulf-Mathies C.
Published: March 2003

A rocket payload able to perform a thorough and independent analysis of the He I 58.43340-nm geocoronal and interplanetary emissions is presented. It includes a sun-pointed resonant absorption spectrometer and a sky-scanning resonant absorption photometer. Both incorporate a similar helium resonance cell of original design featuring a most flexible pressure scanning capability and an accurate pressure measuring device, so that scanning by wavelength bandpasses from 20 down to 1 pm can be achieved. A description of the design and calibration of the instrument is given, followed by an indication of its successful operation in flight.
An interferometric technique for transient phase shift measurements in an electron-beam-pumped laser
Authors: Scheps Richard , Hunter R. O. , Oldenettel J. R.
Published: March 2003

An interferometric technique designed to measure optical homogeneity in an electron-beam-pumped plasma is described and characterized. The system provides a two-dimensional transient phase shift contour mapping of the excited region, at any time during or after the excitation pulse. The basic intrument is a 7-cm-field, 5-m Mach-Zehnder type interferometer coupled to a specially configured 2-m e-beam-pumped sample chamber. By virture of ’’e-beam partitioning,’’ absolute fringe shifts can be measured in a single shot. This relaxes the usually severe requirements on vibration isolation associated with systems of this size, and simplifies the overall mainframe construction. A short-pulse XeF discharge laser, developed specifically for this application, is also described, and sample interferograms are presented for e-beam-pumped noble gas and noble gas–NF3 mixtures. A ray calculus model is applied to the analytical interpretation of the interferograms produced by this technique. This model has general applicability to ray propagation in graded index media and is discussed in some detail.
Technique for measuring the beam shape of pulsed lasers
Authors: Prasad C. R. , Yoganarasimha A. , Venkateshan S. P. , Nagaraju T. G.
Published: March 2003

A simple technique for the measurement of the beam shape parameters of pulsed lasers, with just a single pulse of the laser is described. It involves the use of several beam dividers inclined at very small angles to the beam axis, reflecting the beam back to a screen or a phosphor placed near the exit of the laser. The reflected images are then photographed by a camera to yield the beam parameters.
Versatile type miniature diamond anvil high-pressure cell
Authors: Yamaoka S. , Fukunaga O. , Shimomura O. , Nakazawa H.
Published: March 2003

A miniature diamond anvil high-pressure cell 42 mm in diameter, 18 mm thick, and 150 g in weight has been constructed. The cell is loaded into a piston–cylinder type pressing device with an alignment mechanism and compressed to a desired pressure. After the pressure is clamped by three screws, the cell part is taken out. Thereby, in spite of the small and simple cell, pressure can be generated easily and steadily up to 200 kbar. Because the cell is small and light enough to be mounted on a usual goniometer head, and has large openings towards both the top and bottom, it can widely be used as a versatile apparatus for research at high pressure.
Two-megavolt divider for pulsed high voltages in vacuum
Authors: Pellinen Donald G. , Di Capua Marco S.
Published: March 2003

This paper describes the development of a resistive voltage divider to measure pulsed voltages in excess of 2 MV in vacuo for approximately 100 ns. The monitor can measure either positive or negative polarity by changing the low voltage insulator and reversing the remainder of the insulators and gradient rings.
Grid-gated photomultiplier photometer with subnanosecond time response
Authors: Barisas B. George , Leuther Michael D.
Published: March 2003

A grid-gated photomultiplier has been used in the construction of a subnanosecond-time-resolved photometer. The photocathode is gated on during a sampling window which occupies 4 ns of an 8-ns mode-locked ion laser cycle. The 0.5-ns rise-time sampling window is derived from the mode-locker drive signal and can be adjusted in phase relative to the incident laser light pulses. By resolving scattered light pulses from long-lived fluorescence, the photometer affords a 20-fold reduction in scattered light interfering with photobleaching recovery measurements of low-level fluorescence. Moreover, it has permitted the time-domain measurement with dc circuitry of fluorescence lifetimes as short as 0.7 ns. This time response is achieved using a photomultiplier which, in the absence of grid gating, exhibits an anode pulse rise time of 18 ns. Additional applications of this device and of a related narrow-window sampling photometer currently under development are discussed.
Automatically triggered digital integrator in flame atomic absorption spectrometry with discrete nebulization
Authors: Goto K. , Uchida T.
Published: March 2003

An automatically triggered digital integrator and the specific electronic circuits to measure the aspiration time was constructed and applied to flame atomic absorption spectrometry with discrete nebulization. The integrated signal was proportional to the absolute amount of the element in the sample solution injected. The ratio on the integrated signal to the aspiration time was proportional to the concentration of element in the sample solution irrespective of the volume injected. The reproducibility of the ratio method was 0.5%–1% for the sample volume ≳40 μl of 5 ppm Cu solution.
Automatic calibration circuit for a deep level transient spectrometer
Authors: Troxell J. R. , Watkins G. D.
Published: March 2003

A sample calibration circuit is described for a Deep Level Transient Spectroscopy (DLTS) spectrometer which is simple to use and does not interrupt the normal operation of the spectrometer. The circuit calibrates the entire spectrometer, and does not require an independent determination of sample capacitance.
Sweep devices for picosecond image-converter streak cameras
Authors: Cunin B. , Miehe J. A. , Sipp B. , Schelev M. Ya. , Serduchenko J. N. , Thebault J.
Published: March 2003

Four different sweep devices based on microwave tubes, avalanche transistors, krytrons, and laser-triggered spark gaps are treated in detail. These control circuits are developed for picosecond image-converter cameras and generate sweep pulses providing streak speeds in the range of 107 to 5×1010 cm/s with maximum time resolution better than 10−12 s. Special low-jitter triggering schemes reduce the jitter to less than 5×10−11 s. Some problems arising in the construction and matching of the sweep devices and image-streak tube are discussed. Comparative parameters of nanosecond switching elements are presented. The results described can be used by other authors involved in streak camera development.
Mechanical cell separator
Authors: Lenz Peter
Published: March 2003

This apparatus separates populations of cells or other particles suspended in a liquid. The cells are examined individually in a narrow rectangular flow channel, and sorted out by a device using high-speed microvalves.
Precision stress measurements in severe shock-wave environments with low-impedance manganin gauges
Authors: Vantine Harry , Chan John , Erickson Leroy , Janzen James , Weingart Richard , Lee Ron
Published: March 2003

We describe new techniques that permit the use of low-impedance manganin stress gauges in chemically reacting shock waves in the 1.0–40.0 GPa range. The rugged, small, and fast response gauge has reproducibility better than 2% when used in conjunction with a pulsed bridge circuit and adjustable, current-regulated power supplies. Techniques are presented for fabricating the transducer package, calibrating the bridge circuit and oscilloscopes, designing the drive system, and reducing the data. Data are presented for planar impact experiments performed with a 102-mm gas gun on high-explosive samples. In particular, we directly measured the Chapman-Jouquet pressure in the explosive RX03-BB [92.5% triaminotrinitrobenzene (TATB)/7.5% polychlorotrifluoroethylene (Kel-F binder)] as 28.2±0.6 GPa. These new developments open the possibility of applying low-impedance manganin gauges in chemically reactive hydrodynamic flows such as the evolution of a shock wave into a detonation wave.
Rapid scanning magnet power supply for a high resolution mass spectrometer
Authors: Greenwood G. J. , Stewart J. F. , Cantor D. M.
Published: March 2003

A modification to the CEC 21–110 mass spectrometer that permits the utilization of a stable programmable magnet power supply to allow rapid scanning with minimum reset time under either manual or computer control is described.
Reply to ’’Comment on pulsed high-density source cesium atoms’’
Authors: McCullen John D. , Jones D. W.
Published: March 2003

The authors respond to the comments by the TRW group on their theoretical model [AIP].
Spatial imaging detector system for pulsed plasma extreme ultraviolet diagnostics
Authors: Richards R. K. , Moos H. W. , Allen S. L.
Published: March 2003

A spectroscopic instrumentation system is described which forms one-dimensional monochromatic EUV images of pulsed plasma sources. The system uses a small monochromator and a 22 anode microchannel plate detector to simultaneously view 22 chords of the plasma at the wavelength of a given impurity emission with 100 μs resolution. Brightness profiles are measured and stored in a minicomputer at up to 400 time points during a single discharge. If the discharge is cylindrically symmetric, this data can be Abel inverted directly to produce the volume emission rates and impurity density profiles during the discharge. The design, construction, and testing of the system are described, as well as its performance on the Alcator A tokamak.
Temperature-controlled x-ray diffraction stage for simultaneous monitoring of structural and dimensional changes, with specimen straining capability
Authors: Ling Hung C. , Kaplow Roy
Published: March 2003

An x-ray diffraction stage has been constructed which allows following structural and precise dimensional changes simultaneously as a function of temperature. It also permits manual (tensile) straining of samples, in situ, at any point in a phase transformation sequence (temperature/phase-structure) to examine the interplay between stress (or strain), temperature variation and phase transfromation behavior.
Method for measuring evaporation rates of complex oil mixtures with low ambient vapor pressures
Authors: Baek S. H. , Harris J. E. , Brock J. R.
Published: March 2003

A new experimental technique has been used to study the evaporation rates of complex hydrocarbon oils with low ambient vapor pressures. This technique follows the evaporation of an oil film on a piezoelectric quartz crystal in vacuum. Reasonable agreement is found between vapor pressure measurements of dioctylphthalate at 25 °C by this technique and values reported in the literature. Experimental evaporation rate data at 25 °C by this method are also given for four complex oils; No.2 diesel oil, ’’100 pale oil’’ and two crude oils.
Cross section measurements using a Cs vapor target of novel design
Authors: Meyer F. W.
Published: March 2003

A Cs vapor target is described that uses a surface ionization detector inside the target chamber for direct Cs density determination and whose length is variable, permitting variation of the target thickness at constant target density. By use of a variable length target, accurate cross sections are determined that do not require knowledge of the ’’effective’’ target length. Sample cross section data obtained using this target are shown for electron capture by H+ and H0 and electron loss by H− in Cs vapor at 1000 eV.
CO2 interferometer operation in doublet III
Authors: Baker D. R.
Published: March 2003

A CO2 laser interferometer is used for measuring the average free electron density along a vertical path in Doublet III, a large fusion research tokamak. The CO2 laser is used together with a colinear HeNe laser to form a two wavelength interferometer which is capable of measuring plasma fringe shifts which are much less than the fringe shifts due to mechanical vibrations. This diagnostic has been shown to be able to resolve plasma electron fringe shifts smaller than 1/17 of a fringe during the pulsed operation which causes mechanical motion resulting in as many as 10 fringe shifts. The interferometer is operated in the Michelson configuration with a total double path length through the plasma of 6 m. The density resolution then is better than 2×1012 cm−3. A density resolution of about 0.5×1012 cm−3 has been achieved during relatively quiet operation.
Interferometer for the determination of strains due to domain switching in ferroelectrics
Authors: Allensworth Dwight L.
Published: March 2003

A thermally stable double beam laser interferometer for the measurement of mechanical strains due to domain switching in ferroelectric materials is described. Sample sizes vary from 0.25 mm to 5 mm in thickness, and maximum strains produce from 1 to 50 fringes in the data. A quadrature detection scheme provides the resolution which is required to interpolate accurately the fringe record and determine the direction of surface mechanical displacement. Specific sample mounting techniques are also developed in order to attain well-defined loading conditions. Two sample holders, one for mounting very thin discs and the other for 5 mm cubes, are described. They induce minimal mechanical loadings on the samples. Typical data exhibiting the effects of domain switching due to an applied electric field are shown for the hot-pressed ceramic PZT 65/35.
Coaxial coupler for a 9 GHz EPR/ENDOR cryostat
Authors: Isaacson R. A. , Lulich C. , Oseroff S. B. , Calvo R.
Published: March 2003

We describe a coaxial coupler for 9 GHz EPR/ENDOR system operating between 1.4 and 300 K. This system, besides being sufficiently stable to minimize microphonic noise and drift, allows simple sample chaning.
Novel magnet-cryostat for hall effect studies at low temperature
Authors: Menezes Cornelius
Published: March 2003

We describe a simple electromagnet-cryostat design in which the poles of the electromagnet enter the specimen chamber of a liquid nitrogen cryostat. The arrangement enables fields of sufficient strength and uniformity to be obtained with a moderately small diameter of pole piece and a conventional power supply. Typical measurements on a germanium specimen were made. Experimental data indicate that an improvement in field homogeneity and field strength result from the use of this design compared to conventional nonentrant designs.
Transient photoconductivity apparatus
Authors: Scholl F. W.
Published: March 2003

A description is given of a versatile light source and detection electronics for observation of transient photoconductivity in polycrystalline silicon. The source generates variable optical pulse width and amplitude with penetrating 1.06 μm radiation; the detection electronics allows the observation of low level photocurrents with decay times varying over three orders of magnitude, from 1 μs to 1ms.
Simple experimental method for demonstrating transient frequency shifts in x- and gamma-irradiated quartz crystals
Authors: Bahadur Harish , Parshad R.
Published: March 2003

It is shown that a simple laboratory set-up can be used to demonstrate the occurrence of negative transient frequency shifts as quartz crystals are exposed to ionizing radiations.
Data acquisition and control system based upon the Rockwell AIM-65 microcomputer
Authors: Estler Ron C.
Published: March 2003

A data acquisition and control system based upon the Rockwell AIM-65 microcomputer is described. The system has been designed primarily to enhance laser-induced fluorescence spectra by linearly averaging multiple scans. Results illustrate that the power and flexibility of the low cost system are comparable to more costly averaging instrumentation.
Improving the mach number capabilities of arc driven shock tubes
Authors: Johnson III J. A. , Santiago J. , I Lin
Published: March 2003

New systematatic trends in one of the performance parameters of pressure loaded arc driven shock tubes have been determined. For a given configuration, the Mach number increases with the cube root of capacitor energy; however, the initial driver gas pressure is relatively unimportant. A qualitative model based on the assumption of Joule-preheating by the arc discharge is discussed.
Interfacing a data acquisition system to a computer for on-line analysis
Authors: Kao K. J. , Bamji S. S. , Perlman M. M.
Published: March 2003

An existing Princeton Applied Research Model 131 data acquisition system was modified by adding an inexpensive IMSAI 8048 microcomputer to increase the data transmission speed by a factor of fifty. The system was then interfaced to a PDP 11 minicomputer. The system, microcomputer, minicomputer, interfaces, and communication programs are described. The network enables on-line data acquisition and analysis, facilitating the work in experiments in which large amounts of accurate data are needed.
Free-standing photoresist films for microlithography
Authors: Little J. W. , Callcott T. A. , Arakawa E. T.
Published: March 2003

Microlithography, using computer-controlled electron-beam exposure of radiation-sensitive polymer films called photoresist, is a technique widely used in industry. However, the resolution of existing systems is severely limited by scattering of electrons from the substrate supporting the resist and within the resist film itself. We have developed several techniques for producing and processing free-standing films of photoresist which eliminate the solid substrate and thus the electron scattering from it. These films are also thin enough to reduce scattering within the photoresist significantly. We present some special techniques using free-standing photoresist films which may be utilized to improve the resolution of electron-lithography systems by minimizing the effects of electron scattering in photoresists.
Design and operational characteristics of a compact relativistic electron beam generator for the excitation of short wavelength lasers
Authors: Suzuki T. , Murakami H. , Saito Y. , Yamagishi A. , Inaba H.
Published: March 2003

We have designed and constructed a compact and simple high current relativistic electron beam (REB) generator for the excitation of lasers in the short wavelength region. The REB generator mainly consists of Tesla transformer type high-voltage generator, water pulse forming line, cold cathode electron gun and provides the operational characteristics of 250 keV high energy, 15 kA high current and 15 ns pulse width electron beam.
Angular resolved Raman scattering using fiber optic probes
Authors: Trott G. R. , Furtak T. E.
Published: March 2003

A unique method for obtaining angular resolved Raman spectra is described, the purpose of which will be to study the angular dependence of the surface enhanced Raman effect from molecules adsorbed on metal substrates. Our design employs two flexible fiber optic bundle probes which are optically coupled to the laser and the monochromator respectively. The probes which define the incident and detected angular resolution at 20°, can be independently positioned in 45° azimuthal angle increments and at 0°, 22 1/2°, 45°, and 67 1/2° with respect to the sample surface normal. In a test of the performance of the system, the angular dependence of the Raman intensity from the 992 cm−1 mode of benzene was recorded. The results are in excellent agreement with previous data, thus demonstrating the practicality of our device.
Microprocessor controlled pulse train generator for pulse optically detected magnetic resonance
Authors: Power R. K. , Nishimura A. M.
Published: March 2003

In pulse optically detected magnetic resonance (ODMR) spectroscopy, the precision in the spin relaxation data has been severely limited by instabilities in the timing of the sequence of pulses in the train. A digital pulse train generator is shown to be highly stable with resolution limited only by the response time of the circuit. In addition when the pulse train generator is controlled by a microprocessor, the programming capability allows an extremely wide variety of pulse sequences to be used in pulse ODMR. The use of this and an existing photon counter which is also under microprocessor control allows data manipulation to be made with ease and convenience. The microprocessor controlled pulse train generator is an inexpensive yet highly flexible apparatus useful in pulse ODMR, which can be adapted for application in pulse NMR.
Shock tube techniques in the study of pulverized coal ignition and burnout
Authors: Seeker W. R. , Lester T. W. , Merklin J. F.
Published: March 2003

The extension of shock tube techniques to the study of ignition and burnout of pulverized coal is examined. Nonintrusive optical techniques for characterizing the particle size distribution and the particle temperature as a function of time during burnout are described. Comparison of surface oxidation rates of soot particles and several bituminous coals obtained in the shock tube are in excellent agreement with the higher temperature results found in other apparatus. Because of the wide but controllable ranges of total pressures, oxygen parital pressures, particle temperatures, and coal loadings obtainable, the shock tube offers an additional instrument for the study of solid particle ignition and reactivity under conditions comparable to those found in mine explosions and anticipated in high intensity combustors.
Product transition correlator
Authors: Dewdney P. E.
Published: March 2003

A new kind of digital correlation device is described which resembles a 3-level by 3-level correlator. The product transition correlator consists of a multiplier followed by an accumulator which counts transitions of products from one state to another ranter than the products themselves. Although this approach slightly reduces the signal-to-noise ratio of the accumulated product, it results in a simpler design. Consequently the product transition correlator can operate at much faster sample rates than the conventional 3-level correlators.
Microprocessor system for automated sensory irritation studies
Authors: McCracken M. S.
Published: March 2003

A microprocessor controlled system which provides automatic acquisition and reduction of respiration data produced in sensory irritation studies has been developed. A microprocessor controlled system replaces a manual method where respiration patterns were recorded on a polygraph and then manually counted. A typical experiment consists of a twenty minute exposure and requires two hours to manually reduce the data. The new automated system reduces the data in a few seconds freeing the operator for other tasks. Statistical analysis of the reduced data and tabulation and plotting of results are also provided. Monitoring of the critical steps in the experiment are perfored by the automated system to insure the integrity of the experiments.
Rotating crystal ESR cavity for angular variation studies at room temperature
Authors: Ramani K. , Srinivasan R.
Published: March 2003

We describe an X-band ESR cavity for angular variation studies on single crystals at room temperature. The cavity was found to have a high Q over wide rotation angles.
Aluminosilicate-composite type ion source of alkali ions
Authors: Hughes D. W. , Feeney R. K. , Hill D. N.
Published: March 2003

A thermionic source of singly charged alkali ions consisting of an aluminosilicate-molybdenum emitter assembly rigidly mounted behind a Pierce-type electrostatic focusing structure is described. This ion source is compatible with an ultra-high vacuum environment and has generated intense, high purity ion beams for a continuous operating period of one month.
High-frequency Faraday cup array
Authors: Starke T. P.
Published: March 2003

A high frequency response Faraday cup array has been developed to measure the beam profile and high frequency wave behavior of the Auto-Resonant Accelerator electron beam.
Wall nonuniformity measurement of inertial fusion targets using a rolling technique
Authors: Rensel W. B. , Steinman D. A. , Crawley R. L. , Tanner D. J.
Published: March 2003

Commercial viability of inertial fusion (IF) requires high volume, low cost manufacture of the reactor targets. An important aspect of the manufacturing process is quality assurance of the hollow, spherical fuel containers used as targets. This report presents a rolling technique that can characterize and sort for wall uniformity rapidly and economically. We have demonstrated that shells having offset inner spheres roll at an angle down an inclined plane in accordance with a straightforward mathematical model.
Direct display of electron temperature oscillation in a plasma
Authors: Sengupta D. , Saha S. K. , Sengupta S. N. , Mukherjee S. K.
Published: March 2003

A simple differential technique using a floating Langmuir probe and a hot probe has been used to obtain direct oscillographic display of electron temperature oscillation in a plasma. The reliability of the method has been tested in artificially generated moving striations in the positive column of a cold cathode argon discharge (Id=8 mA; p=0.1 torr; 2r=5 cms).
Addenum heat capacity of a glass–ceramic capacitance thermometer at low temperatures
Authors: Lawless W. N.
Published: March 2003

The heat capacity of a glass–ceramic, capacitance thermometer is reported from 1.8 to 30 K. Below about 5 K, the metal electrodes dominate the heat capacity, and above 7 K, the glass–ceramic dominates. Accurate fitting equations are given.
Voltage and current sensors for a high-density z-pinch experiment
Authors: Ekdahl C. A.
Published: March 2003

Capacitively-coupled transmission-line voltage sensors and inductive-shunt current sensors used in experiments with a high-density gas-embedded z pinch have provided accurate and reliable measurements. Design and construction of these sensors is described, and their calibration is discussed in detail.
Application of a directly exposed self-scanning photodiode array as a linear position sensitive detector in a small-angle x-ray scattering instrument
Authors: Borso C. S. , Danyluk S. S.
Published: March 2003

A linear position sensitive small-angle x-ray detector has been developed which utilizes a directly exposed self-scanning photodiode array cooled to liquid nitrogen temperature to reduce fixed pattern noise. Direct exposure of the array improves the overall sensitivity to 8 keV photons by an order of magnitude over photoconversion techniques. With this improvement in sensitivity, the photodiode array has been effectively used to detect x rays from weakly scattering biological molecules in solution. The slit-like geometry of the photodector elements ideally matches that of a Kratky collimator employed with a low-flux x-ray source to enhance greatly the data collection rate. The detective quantum efficiency and stability of the detector have been determined while taking small-angle scattering measurements of proteins and the results are quantitatively applied to characterize the performance of the instrument.
Instrumentation at temperatures below 1 K
Authors: Anderson A. C.
Published: March 2003

This paper, a guide to the literature, is directed to experimentalists planning to extend their research into the temperature range of 0.01–1 K. Included are discussions of refrigeration, thermal contact and isolation, thermometry, and several examples of how standard physical measurement techniques have been adapted to the temperature regime below 1 K.
Production of 1.25 K 4He without 4He superfluid film
Authors: Goebel John H.
Published: March 2003

A refrigeration process is described which enables the production of a sub-λ-point 4He temperatures without the production of superfluid. The advantages of the process for zero gravity (0-g) and low-noise refrigeration are described. The lowest temperature produced to date is 1.25 K. The process is also useful with other gases for refrigeration; the output temperature is selected by gas type.
Selective fast neutron detector
Authors: Chrien R. E. , Strachan J. D.
Published: March 2003

A ZnO(Ga) scintillator has been developed which selectively detects 14 MeV neutrons in a large 2.5 MeV neutron and hard x-ray background. The detector will be useful in measuring the 14 MeV neutron emission with trace concentrations of tritium in a predominately deuterium plasma during early experiments in the Tokamak Fusion Test Reactor (TFTR) or the Joint European Torus (JET).
High-performance secondary ion mass spectrometer
Authors: Colton R. J. , Campana J. E. , Barlak T. M. , DeCorpo J. J. , Wyatt J. R.
Published: March 2003

A high-performance research-oriented secondary ion mass spectrometer (SIMS), based on a double-focusing mass spectrometer, has been designed, constructed, and evaluated. This instrument is relatively free of some of the instrumental limitations associated with conventional molecular SIMS instrumentation such as energy and mass discrimination. Theoretical design considerations and its construction are discussed. Its performance has been evaluated in various operational modes using a variety of samples and some important instrumental parameters are reported. Finally, the novel and outstanding high-mass capability of this SIMS instrument is demonstrated.
Thermal interlock system with quick response time for high-power magnetic coil systems
Authors: Kubota Y. , Kodaira J. , Miyahara A.
Published: March 2003

A thermal interlock system with a quick response time has been developed to protect high-power magnetic coil systems from thermal overloads. In this system thermal sensors are directly attached to coils and are electrically connected to other components through isolation transformers. The response time of the interlock system is estimated to be less than 1.5 seconds.
Modified electrometer for constant current I–V measurements
Authors: Gallego J. M. , Reehal H. S. , Thomas C. B.
Published: March 2003

A simple circuit is described which when added to a commercial KEITHLEY electrometer (Model 610C) enables the instrument to be used for carrying out current–voltage measurements with any known and constant current, in the range 10−12–10−5 A, passing through a specimen and with up to 100 V dropped across it.
Signal to noise enhancement of lock-in amplifiers
Authors: Neelakantan K. , Dattagupta S. , Rajappan K. P.
Published: March 2003

A lock-in amplifier can be considered to be a special case of the more general box-car averager. Expressions for the output noise voltage of lock-in amplifiers are deduced from the corresponding results derived earlier for box-car averagers. Deviations from the simple (4 RC)1/2 law are shown to exist in the case of nonwhite noise.
Laser power-per-line analyzer
Authors: Fusek Richard L. , Gokay M. Cem , Marcheski Joseph S.
Published: March 2003

The power-per-line analyzer is an instrument designed to provide a continuous real-time display of any laser spectra on an oscilloscope. In this article the HF and DF laser version of this instrument is described. A new continuous drive and electronic calibration method are used, eliminating the need for mechanical and optical recalibration. The wavelength is proportional to the dc voltage generated by the scanner’s angular position transducer, which drives the x axis of an oscilloscope. The relative line intensity is proportional to the dc voltage generated by a pyroelectric detector and drives the y axis of the oscilloscope. The wavelength calibration accuracy of the final instrument is 0.8% full scale, and the resolution is 2 nm.
Determination and optimization of frequency response of constant temperature hot-wire anemometers in supersonic flows
Authors: Bonnet J. P. , Alziary de Roquefort T.
Published: March 2003

In order to achieve turbulence measurements in supersonic flows the frequency response of CTA is tested and improved. A fast and convenient technique to determine electrically the frequency response is proposed; the response is also tested by direct heating of the wire by means of a laser beam. The two techniques are in good agreement. Under certain experimental conditions (M=2, Reφ=400) it is possible to use CTA with a satisfactory frequency response up to 250 kHz and overheat ratios down to 0.07. In these severe operating conditions, the square-wave test technique seems to be not sufficient to ensure optimum settings and it is necessary to use symmetrical bridges with fine adjustment of offset voltage.
Circuit to measure hysteresis
Authors: Peters Robert A. , Refai Talat F.
Published: March 2003

A circuit is described which permits a hysteretic ratio to be graphed versus another experimental parameter. The hysteretic ratio can be defined either: (a) by the two discontinuities of the I–V response (or more exactly the two discontinuities in (dV/dt) or (b) by the two polarity changes (as in ferromagnetic B vs H curves). The circuit features a large dynamic range (≳40 dB with no adjustments) and works well for modulation frequencies between 10−3 and 300 Hz.
Ultraminiature high-power gas discharge lasers excited through high dielectric constant ceramic materials
Authors: Hasson V. , von Bergmann H. M. , Jones E. G.
Published: March 2003

The authors show that millimeter-size high-pressure UV nitrogen lasers can be excited through high dielectric constant materials and provide peak beam powers of 104–105 W.
Adaptation of an ultrahigh vacuum angle-resolving photoemission chamber for sample manipulation and rotation
Authors: Royer W. A.
Published: March 2003

A sample-manipulator attachment to a UHV angle-resolving photoemission system is described which permits the sample to be rotated azimuthally and to be transported to a LEED/Auger optics. The manipulator may be assembled from readily available commercial parts.
Versatile High-throughput filter for altering the spectrum of multiple-frequency lasers
Authors: Greiner N. R.
Published: March 2003

This device filters any desired subset of frequencies from a multiple-frequency laser without reducing substantially either the power in the remaining frequencies or the optical quality of the reconstructed beam. It should be useful in multiple-frequency laser photochemistry and the probing of multiple-frequency laser media.
Low energy ion counting efficiency of a Johnston electron multiplier
Authors: Stickel R. E. , Kellert F. G. , Smith K. A. , Dunning F. B. , Stebbings R. F.
Published: March 2003

We report a measurement of the absolute efficiency of a Johnston Laboratories MMl electron multiplier for detection of 2–4 keV Ne+. The measured detection efficiency depends both on ion impact energy and on the magnitude and direction of an externally applied electric field near the first dynode.
Construction of a new unclipped digital correlator for quasielastic light scattering
Authors: Lempert Walter , Wang C. H.
Published: March 2003

An unclipped digital correlator that we have built has been described. Our digital correlator can be easily incorporated (with only a moderate cost) in an established light scattering laboratory equipped with a computer.
Tunable laboratory extended x-ray absorption fine structure system
Authors: Cohen G. G. , Fischer D. A. , Colbert J. , Shevchik N. J.
Published: March 2003

A new sensitive x-ray monochromator and detector system for performing extended x-ray absorption fine structure (EXAFS) measurements in the laboratory is described. The monochromator combines x-ray focusing optics with rapid elemental tunability. The detection system effectively removes glitches from the data stream, regardless of whether they are due to impurity lines from the x-ray source or if they are due to random instabilities in the incident beam. Used together with a high intensity rotating anode x-ray source, this system can provide synchrotronlike photon intensities, flexibility and resolution, with the easy access and control possible only in the laboratory.
Calorimetric system for recording plasma blowoff and scattered light distributions from laser plasmas
Authors: Villeneuve D. M. , Richardson M. C.
Published: March 2003

A complete system is described for the measurement of the distribution of energy emanating from laser-produced plasmas in the form of (1) plasma blowoff (ions, electrons, neutral particles, and x rays), and (2) scattered laser light. The detectors consist of small modules containing two differential calorimeters in one package, one for each form of energy. Modular autozeroing amplifiers enable the slowly varying signals to be measured by computer with the aid of CAMAC analog to digital converters. The computer is also capable of absolutely calibrating the units in situ. The programs used to record and display the data, and to calculate the fraction of laser energy absorbed, are described.
Broadband superheterodyne tracking circuits for millimeter-wave measurements
Authors: Doane J. L.
Published: March 2003

Superheterodyne stimulus-response measurements can be made with high dynamic range, but are often sensitive to oscillator frequency drift and noise. The usual techniques for reducing this sensitivity often become impractical at millimeter-wave frequencies and above. This paper describes a feedforward tracking technique and its application to single frequency millimeter-wave interferometry and Doppler-shift scattering measurements on tokamak plasmas. Swept frequency transmission measurements can also be made with high dynamic range using this technique.
Compact resonance absorption spectrometer to monitor the profile of the solar He 58.4 nanometer line
Authors: Crifo J. F. , Seidl P. , Delaboudinière J. P. , Schmidtke G.
Published: March 2003

A miniature resonance absorption spectrometer is able to perform a routine monitoring in space of the line profile and intensity of the He i resonance line from the solar disk with a time resolution of about 1 min and a spectral resolution of 105. It consists of a predispersive spectrometer incorporating a helium gas absorption cell. The instrument has been designed to meet a small size and weight. It was tested on a rocket flight in June 1976. The construction, principles of operation, and laboratory calibration of the instrument are presented. Its capability to resolve details of the order of 0.3 pm FWHM and its sensitivity to the intensity of line wings three order of magnitudes fainter than the peak of the line have been established by laboratory investigation.
Continuous ammonia monitor using a Stark microwave cavity resonator
Authors: Uehara Hiromichi , Ijuuin Yasuharu , Morino Yonezo , Kamidate Tamio , Nakamura Akiya , Imai Hideo
Published: March 2003

An ammonia monitor has been made by using a rectangular Stark microwave cavity tightly coupled through an iris to a Gunn oscillator. The Stark electrode installed inside the cavity is provided with a 100 kHz sinusoidal modulation voltage and a dc sweep voltage. The oscillation of the Gunn diode is tuned with the coupled Stark cavity to a frequency near a J,K=3,3 transition (23870.1 MHz) of ammonia. By fixing the Stark dc bias to a voltage which gives a peak intensity of the derivative output of the electric-resonance signal, ammonia is continuously monitored. An extremely good long-term stability is obtained. The noise level corresponds to 0.08 ppm of ammonia.
Two-filter monitor for atmospheric 222Rn
Authors: Schery S. D. , Gaeddert D. H. , Wilkening M. H.
Published: March 2003

A two-filter, continuous monitor has been developed for atmospheric 222Rn. Features include a sensitivity of better than 0.01 pCi/l, a high specificity for 222Rn, and immediate start up capability. The monitor has been computer modeled to facilitate calibration and selection of operating parameters. The filters are stationary and require no moving parts for control. Field trials indicate high reliability and maintenance-free operation for periods of a week and longer.
Multichannel digitizer for routine monitoring of ion emission from laser-driven implosions
Authors: Raven A. , Rumsby P. T. , Watson J.
Published: March 2003

The design and construction of a multichannel Faraday cup detector and digitizer system for routine monitoring of ion emission characteristics from laser driven implosions are discussed. Experimental results are presented to demonstrate the operation of the device.
Production of flat top beam profiles for high energy lasers
Authors: Grojean R. E. , Feldman D. , Roach J. F.
Published: March 2003

Production of uniform (flat top) high energy laser beam profiles with relatively little beam energy loss is possible through the use of a modified kaleidoscope, multiple reflection beam scrambler.
Wheatstone bridge technique for magnetostriction measurements
Authors: Sullivan Michael
Published: March 2003

A basic Wheatstone bridge, with additional electronic instrumentation, has been used in the measurement of magnetostriction. This method allows a resolution of ∼10% on measurements of magnetostrictions less than 0.75 parts per million.
Low energy H atom analyzer using a cesium heat pipe
Authors: Brisson D. , Baity F. W. , Quon B. H. , Ray J. A. , Barnett C. F.
Published: March 2003

The efficiency of detecting H and D atoms (E<1 keV) escaping a plasma has been increased by use of a cesium vapor cell to form negative ions by electron attachment collisions. A 30 cm long heat pipe confines the cesium to a localized region. The resulting negative ions are energy analyzed with a single-channel, parabolic parallel-plate analyzer and detected by a channel multiplier. The H0 conversion efficiency was 10−2 at 100 eV, increasing to 3.8×10−2 at 500 eV. For a H0 energy of 100 eV, the analyzer is 2.5 orders of magnitude more efficient than a comparable N2 stripping cell analyzer. The analyzer has been used to measure ion temperatures as low as 30 eV on the EBT Plasma experiment.
A new method for measuring the particle size distribution of aerosols
Authors: Tropp R. J. , Kuhn P. J. , Brock J. R.
Published: March 2003

A new method (electronic cascade impaction) of measuring the particle size distribution of aerosols is presented, and an instrument we call an electronic cascade impactor (ECI) which uses the method is described. Aerosol particles are charged in a unipolar charger and enter a multistage cascade impactor. Each collection stage and the final filter is isolated electrically from other parts of the impactor and connected to an electrometer detector. Particles deposit on the collection stages according to their aerodynamic diameters, and from the associated electrical current the deposition rate onto each stage and the particle size distribution can be determined. Calibration data for the ECI are presented. The ECI has been used to study atmospheric aerosol dynamics in real time, and typical data are given. The ECI has proven to be relialbe in several hundred hours of laboratory and field use and other versions employing the same general method should prove useful in a wide variety of measurement situations.
Production of ribbon quenched samples using an arc furnace
Authors: Tutzauer H. , Esquinazi P. , de la Cruz M. E. , de la Cruz F.
Published: March 2003

We describe a new device to produce ribbons of disordered metals by ultrarapid quenching combining an arc furnace with a rotating cylinder. The characterization of samples of disordered La70 Cu30 and La76Au24 prepared using this method shows good agreement with those obtained by other authors for the same alloys.
Design of a guarded electrode
Authors: Collins R. E. , French O. R.
Published: March 2003

A simple technique is described for constructing a plane guarded electrode which has a very small gap between electrode and guard ring.
A roller-plate technique for preparing uniform thin films from the melt
Authors: Suzuki Takeyuki , Kōda Michiaki , Hashimoto Yasuharu , Satō Reiko
Published: March 2003

A new quenching technique of the melt is described. By using this, it is possible to make uniform, flat and thin films. Cooling rate is fast enough to quench Bi2O3 into an amorphous solid, which had been impossible by the gun technique.
Heat capacity cryostat and novel methods of analysis for small specimens in the 1.5–10 K range
Authors: Forgan E. M. , Nedjat S.
Published: March 2003

We describe a method for measuring heat capacity of small specimens in the 1.5–10 K range by means of thermal relaxation over that range. Our methods of calibration and analysis make use of the simple properties of the thermal link between specimen and its surroundings, and offer several advantages. The cryostat has been used in magnetic fields of up to 4.5 T, and simple relationships for the magnetoresistance of heat links and thermometer have been determined. Measurement of the heat capacity of a 90 mg copper sample shows that the method is accurate to 1%.
Beamlet steering by aperture displacement in ion sources with large acceleration-deceleration ratio
Authors: Conrad J. R.
Published: March 2003

The steering of ion beamlets by aperture displacement is studied analytically and numerically for the case of triode extractors with large acceleration-deceleration ratios. Here the acceleration-deceleration ratio ε is defined by ε≡Va/Vb, where Va and Vb are the potentials applied to the second and third grids of the extractor, relative to the beam forming grid at zero potential. Both slit and round apertures are examined. When the second-order effects of space charge and potential sag in the extractor are included in the analysis, good agreement with numerical simulations is obtained.
Fast pulsed gas valve
Authors: Keyser C. J. , Dembinski M. , John P. K.
Published: March 2003

A fast valve which can inject gas pulses with durations from 25 to 400 μs into a vacuum system is described. Quantities up to 5 Torr l can be injected. A pressure rise time of ∼0.5 Torr/μs has been determined at the valve opening. A fast opening time is achieved by having a magnetically accelerated ring collide with a disk which is used as a vacuum seal. Gas pulse parameters have been measured with a fast ionization gauge.
Detection of cathodoluminescence of Giemsa stain and its applications
Authors: Basu S.
Published: March 2003

Giemsa stain shows an intense and durable cathodoluminescence (CL) when studied at 20–30 kV with a quartz transmission light pipe–photomultiplier system in a scanning electron microscope. Clear CL images of Giemsa-stained chromatin, nuclei, and chromosomes were recorded at low electron does (approximately 10−5–10−4 C/cm2). Careful and control experiments have suggested that true cathodoluminescence of Giemsa has been recorded. The CL emission of Giemsa is attributable to one of its ingredients, eosin-y, whose bromine molecules apparently act as radiation scavengers.