bluuebunny/crossref_metadata_2025 huggingface dataset:
Wide-bandwidth analog correlator and its application to mode-locked laser measurements
Authors: Ramsey J. M. , Hieftje G. M. , Haugen G. R.
Published: March 2003

A new instrument for the analog determination of correlation functions of wide-bandwidth signals is described and characterized. The instrument is comprised of microwave electronic components; a double-balanced mixer performs the multiplication operation involved in the correlation process, whereas a constant-impedance line stretcher introduces the variable delay. Measurements indicate that the correlator has a bandwidth of approximately 3 GHz. It is shown that this inexpensive and simple device can be used as a diagnostic tool for mode-locked argon-ion lasers when used in conjunction with a fast photodiode detector.
Schlieren technique for the measurement of low-level concentration fluctuations
Authors: Shilo K. , Appelbaum G. , Noter Y.
Published: March 2003

A device for the measurement of concentration fluctuations in flowing gases which can be used to establish and control the degree of mixing is described. The design is based on an improved laser-schlieren technique combined with photometric detection. The device operates on-line and has high sensitivity and fast response. A quantitative sensitivity evaluation is made and checked experimentally. The device is used to characterize the performance of some simple mixing configurations. The detection limits for various gas mixtures are given.
A nanosecond temperature-jump apparatus for high pressures
Authors: Liphard Klaus G.
Published: March 2003

An apparatus is described which extends the time range of the temperature-jump technique at high pressures to the nanosecond region. A temperature increase of a few degrees can be obtained within approximately 50 ns by discharging a high-voltage coaxial cable. Reactions are followed spectrophotometrically. Details of the temperature-jump microcell and high-pressure autoclave are presented. An application of this method is given for the reaction of phenol red with NH+4/NH3 buffer at 1 and 2000 bars.
A compound carbon thermometer for the temperature range 0.3–100 K
Authors: Adolf A. , Djerassi H. , Leszczyszyn J.
Published: March 2003

A compound carbon thermometer consisting of an abreast connection of a carbon Speer resistor and a carbon Allen-Bradley resistor was tested in the temperature interval 0.3–100 K, an interval which generally requires two independent resistors to be covered. The characteristics, sensitivity, and analytical handling of the resistance versus temperature data are discussed and compared with the corresponding behavior of other thermometers. The satisfactory performance of the compound carbon device contributes to the extension of wide-range thermometry to 0.3 K.
High-pressure stopped-flow apparatus up to 3 kbar
Authors: Sasaki Muneo , Amita Fujitsugu , Osugi Jiro
Published: March 2003

A high-pressure stopped-flow apparatus was constructed which could be operative at hydrostatic pressures up to 3 kbar. Some preparative results on anionic σ-complex formation reactions are presented up to 1.5 kbar between 2,4,6-trinitrobenzene (I) and hydroxide ion and between compound (I) and sulfite ion in water. It was found that this apparatus was sufficient to follow a chemical reaction whose half-life was longer than several milliseconds.
A differentially pumped low-energy ion beam system for an ultrahigh-vacuum atom-probe field-ion microscope
Authors: Amano Jun , Seidman David N.
Published: March 2003

An ultrahigh-vacuum (UHV) differentially pumped low-energy (50–3000 eV) ion beam system for the in situ irradiation of specimens in a UHV atom-probe field-ion microscope (FIM) was designed and constructed. The ion beam system consisted of a Finkelstein-type ion source, an Einzel lens, and a magnetic mass analyzer. The ion source was connected to the analyzer chamber by small apertures which resulted in differential pumping between the ion source and the analyzer chamber; during a typical in situ irradiation of a specimen in the atom-probe FIM the total pressure was maintained at ≈10−7 Torr. In the case of helium ion irradiation the optimum ion-current density was ≈0.5 μA cm−2 for 300-eV He+ ions at the atom-probe FIM specimen. After the completion of a helium ion irradiation the pumpdown time from 5×10−7 to ≈3×10−10 Torr in the atom-probe FIM chamber was 0.5 h.
A high-temperature and high-field nuclear magnetic resonance instrument
Authors: Ploumbidis D.
Published: March 2003

In the course of constructing an apparatus suitable for studies of nuclear magnetic resonance at high tempertures and high fields we developed a furnace with a new heating element which has been applied for the first time to NMR studies. The furnace can work in a 8-T field of a superconducting magnet system at temperatures up to 2200 K. Because of its geometrical form the heating element does not cause any measurable disturbing magnetic fields resulting from the heating current, and has many advantages compared to conventional heating elements. The temperature at which, up to this moment, we could observe NMR in external fields of 8 T amounts to 1200 K. The specifically adapted NMR probe works at radio frequencies up to 50 MHz. With this apparatus we carried out measurements of the magnitude, sign, and temperature dependence of the Knight shift of Mo in molybdenum metal.
A capacitance-based micropositioning system for x-ray rocking curve measurements
Authors: Miller G. L. , Boie R. A. , Cowan P. L. , Golovchenko J. A. , Kerr R. W. , Robinson D. A. H.
Published: March 2003

Certain types of x-ray experiments require very precise angular positioning of crystals in the vicinity of the Bragg reflection condition. A system applicable to some measurement of this type is described which achieves a long-term angular stability of ∼10−7 radians, coupled with a linear angular readout. This is achieved through a novel capacitance sensing system which provides angle measurement, together with the use of an auxilliary servo loop based on the Bragg condition to ensure long-term overall angular stability.
A data acquisition and control system based on the new Commodore PET microcomputer
Authors: Jedju T. M.
Published: March 2003

A powerful data acquisition and control system at a very low cost is presented. This is made possible by providing the interfacing hardware and supporting software to integrate the new and low-cost consumer-marketed ’’personal computers’’ into a useful and powerful data acquisition system. This system can be configured to the user’s need at any given time, simply by writing the appropriate software. In addition to its computing power, the system has been programmed for use as a transient digitizer–multichannel analyzer with a minimum of 12 μsec per channel, a data and curve fitter, a general x-y recorder and averager, and a general purpose lab equipment controller. The system developed is, in many respects, at least as powerful as a DEC-PDP 11/04 system—at a small fraction of the cost.
Determination of the theoretical capacitance of a concave capacitance sensor
Authors: Abouelwafa M. S. A. , Kendall E. J. M.
Published: March 2003

The practical use of four concave capacitance plates for determining in situ volume fractions in two-phase pipelines has been amply demonstrated. In this letter, the system is analyzed theoretically using a microstrip technique and the results are compared with experimental data.
X-band cavity for ESR experiments
Authors: Linari R. , Tronconi A.
Published: March 2003

We describe an x-band cavity for ESR experiments built to produce the modulation of the magnetic field without using any coil. The modulation is obtained with a current circulating in the cavity walls. The mechanical construction of this device is simple and inexpensive and allow the reduction of the magnetic air gap of the spectrometer.
Range-resolved Brillouin scattering using a pulsed laser
Authors: Guagliardo J. L. , Dufilho H. L.
Published: March 2003

In order to acquire the three-dimensional information (frequency, depth, and intensity) required for a range resolved Brillouin spectrum, either a multichannel or integration technique must be employed. This paper describes a system in which many laser shots are used to ’’build up’’ one Brillouin spectrum for each range gate in an ocean subsurface experiment.
New experimental apparatus for the study of the Bénard–Rayleigh problem
Authors: Moreno J. , Jimenez J. , Córdoba A. , Rojas E. , Zamora M.
Published: March 2003

A new experimental system to measure the equivalent thermal conductivity of a liquid with regard to the Bénard–Rayleigh problem was constructed. The liquid is enclosed within walls of polymethylmethacrylate between two copper plates in which there are thermocouples to measure the difference in temperature between the lower and upper surfaces of the layer of liquid. Heat flux is measured by means of a linear heat fluxmeter consisting of 204 thermocouples in series. The fluxmeter was calibrated and the linear relationship that exists between the heat flux and the emf generated was verified. The thermal conductivity of the polymethylmethacrylate employed was measured and measurements of the equivalent conductivity in cylindrical boundaries of two silicone oils were made. The critical value of the temperature difference and the contribution of the convective process to the transmission of heat were determined.
Monolithic crystal monochromators for synchrotron radiation with order sorting and polarizing properties
Authors: Materlik G. , Kostroun V. O.
Published: March 2003

Two novel types of x-ray monochromators which eliminate unwanted higher orders usually present in crystal monochromatized synchrotron radiation beams have been used successfully in spectroscopic studies. The design of the monochromators is based on the refractive index correction’s dependence on wavelength and relative orientation of crystal surface to reflecting Bragg planes. In addition to the order sorting property, both types of monochromators can be used to decrease or increase the reflected beam cross section by Bragg focusing, and in one type, to determine the polarization state of the diffracted beam.
Varactor tuned ultrahigh frequency SQUID magnetometer
Authors: Long A. P. , Clark T. D. , Prance R. J.
Published: March 2003

We describe a 430-MHz SQUID magnetometer in which both the resonant frequency of the SQUID tank circuit and the input/output impedances of the following 4.2 K GaAs FET amplifier are varactor controlled. The intrinsic energy sensitivity of the magnetometer, in full flux lock from dc to 5 MHz, is 6.8×10−32 J/Hz (≡4×10−6Φ0/√Hz flux sensitivity). The figure of merit is 2.1×10−31 J/Hz.
Low inductance spark gap switch for Blumlein-driven lasers
Authors: Keto J. W. , Raymond T. D. , Walsh S. T.
Published: March 2003

We report the design of a low inductance park gap switch for Blumlein-driven lasers which is highly reliable under conditions of high repetition rate and high average power. The reported spark gap has provided reproducible pulse waveforms without maintenance for 108 shots in a Blumlein-driven nitrogen laser. When operated with a nitrogen–SF6 mixture in the laser tube, this laser provided peak powers in excess of 3 MW at 5-Hz repetition rate and an average power of 0.5 W at 120-Hz repetition rate.
CH2 molecular beam source
Authors: Porter R. A. R. , Grosser Arthur E.
Published: March 2003

A molecular beam source of CH2 is described. Coaxial beams of methylene halide and alkali metal react and the mixture is formed into a molecular beam. Passage through a mechanical velocity selector rotating at a suitably high speed purifies the beam, separating light, fast CH2 from heavier, slower contaminating species.
Balanced bias differential current amplifier circuit for detection of laser induced multiphoton ionization
Authors: Adams T. E. , Morrison R. J. S. , Grant E. R.
Published: March 2003

A circuit is described for the production of an amplified, single-ended output signal from a well-shielded multiphoton ionization cell.
Filament chucks for multifilament ion sources
Authors: Conrad J. R. , Horne S. F. , Pirkle D. R. , Torti R. P.
Published: March 2003

A simple method for fabricating filament chucks for multifilament ion sources is described.
Power measurement for frequencies up to ∼1 GHz using a sampling oscilloscope and a low-frequency multiplier
Authors: Anderson John M.
Published: March 2003

Accurate measurement of electrical power above ∼1 MHz is accomplished by reconstruction of the voltage and current waveforms at a lower frequency using a sampling oscilloscope. The low-frequency waveforms are then multiplied in a 4-quadrant tranconductance-type multiplier module.
Image accumulation, storage, and display system for a scanning transmission electron microscope
Authors: Zubin J. A. , Wiggins J. W.
Published: March 2003

This paper describes a high resolution scanning transmission electron microscope data collection, storage, and display system. Included are a novel analog-to-digital converter, a digital hardware divider, a direct memory access interface to a PDP 11/20, a flicker-free gray scale TV display, two new gray scale hardcopy devices, and a software description of the system. The system described here accepts three 8-bit channels of image data from a single picture element every 30 μs. Each picture element intensity is measured simultaneously by three detectors. Scans of 64, 128, 256, or 512 lines of picture elements are provided. All the data are stored on one of eight disk files, and one of the three simultaneous data channels is displayed on a digitally refreshed TV screen in real time. Production of hard-copy images and magnetic tape images, and other manipulations of the data are provided after data accumulation is terminated.
High pressure clamp for electrical measurements up to 8 GPa and temperature down to 77 K
Authors: Bandyopadhyay A. K. , Nalini A. V. , Gopal E. S. R. , Subramanyam S. V.
Published: March 2003

A compact clamp-type high pressure cell for carrying out electrical conductivity measurements on small solid samples of size 1 mm or less at pressures upto 8 GPa (i.e., 80 kbar) and for use down to 77 K has been designed and fabricated. The pressure generated in the sample region has been calibrated at room temperature against the polymorphic phase transitions of Bismuth and Ytterbium. The pressure relaxation of the clamp at low temperatures has been estimated by monitoring the electrical conductivity behavior of lead.
Simple noise level digitizer
Authors: Latham Don J.
Published: March 2003

A simple, high-precision technique for measuring the rms value of noise signals is described. The technique is based on a statistical theory relating the number of threshold crossings of a noise signal to its variance.
Design, description, and application of a micromanipulator suitable for use in closed systems
Authors: van Netten C. , Belton P.
Published: March 2003

A design for a compact micromanipulator is presented. The range and sensitivity of movements it provides are comparable with large, benchmounted instruments, yet several of these micromanipulators can be mounted in a small chamber holding an electrophysiological preparation. With the use of such a chamber the environment of its contents can be closely controlled yet access is maintained at all times.
Precision analog simulator for a Josephson junction
Authors: Yagi Akihiko , Kurosawa Itaru
Published: March 2003

A precision analog simulator for a Josephson junction has been developed. This simulator is composed of several unit circuits and its sources of the error are tractable. The term corresponding to sinφ is generated by an integrator with a resetting switch and a sinusoidal function generator. The time dependence of junction voltages and the I–V characteristics are obtained for a current driven Josephson junction and compared with the analytical solutions for nonhysteretic case. The sources of the error are investigated in this simulator. In order to simulate quasiparticle conductance, an adjustable nonlinear resistance network was also constructed.
Method for producing thin sheets of proton-sensitive CR-39 plastic track detectors
Authors: Kinoshita K. , Price P. B.
Published: March 2003

Uniform, high-quality sheets of CR-39 (allyl diglycol carbonate) from ∼25 to ∼500 μm thick can easily be made by curing the initiated monomer between thin glass plates within a suitable gasket in a hot water bath or in an air oven.
Calorimeter for simultaneous, low-temperature measurements of energy release and of resistivity recovery in irradiated metals
Authors: Jackson J. J.
Published: March 2003

In this paper are described an irradiation calorimeter and data acquisition system used for simultaneous determinations of the rates of energy release and of resistivity recovery during anneals at low temperatures of irradiated metals. Both rates are measured on the same sample. the system provides efficient heat transfer from the specimen during irradiations and a good, reproducible degree of thermal isolation of the specimen during anneals. Necessary corrections to the raw data are discussed. The application of these measurements to determination of the energy released by interactions which immobilize self-interstitial atoms is described and illustrated by data from the recovery between 12 and 35 K of platinum irradiated with 20.6-MeV deuterons.
Wide-angle scattering configuration for laser Doppler measurements of electrophoretic mobility
Authors: Uzgiris E. E. , Cluxton D. H.
Published: March 2003

A wide-angle, crossed-beam laser Doppler scattering configuration is described. This configuration is optimized for measurement of electrophoretic mobility of blood cells. It is easy to align and maintain aligned and is stable against microphonic disturbance. The optimum scattering angle for blood cells is shown to be in the range of 25°–45°, a condition that is easy to implement with this configuration and within the geometrical constraints imposed by the use of narrow gap rectangular electrodes for applying an electric field.
Novel method for measuring high-temperature furnace gradients
Authors: Ma C. K. , Ohtsuka M. , Bedford R. E.
Published: March 2003

We describe a method for measuring the temperature distribution in high-temperature furnaces with thermocouples that is independent of thermocouple calibration or inhomogeneity errors, and of the presence of leakage voltages on the thermocouple. The method uses several thermocouples and the wire bridge method of true temperature indication; the distribution is obtained from the rate of change of furnace temperature and the time between successive melts. We illustrate the method using gold as the indicator, and in this case achieve an accuracy approaching ±0.2 °C.
Nondimensional tuning of accelerating structures
Authors: McKeown J. , Schriber S. O.
Published: March 2003

A method is described for tuning coupled-cavity structures without the need for iterative machining. Small field displacements caused by the rotation of alternate segments of on-axis coupled structures are sufficient to change the coupling cell frequency without having a significant effect on the accelerating cell frequency. The results from a nine-cell experimental model have implications in the suppression of nonaxially symmetric modes which cause beam blow up in cw microtrons.
Some carbon resistance thermometers in low magnetic fields
Authors: Crooks Michael J.
Published: March 2003

The magnetoresistance in the liquid helium temperature range has been determined for a number of Ohmite/Allen–Bradley 1/8 W and older Allen–Bradley 1/10 W resistors in magnetic fields from 0.01 to 0.1 T. The new resistors show ΔR/R∝B1.3±0.2; the older resistors show negative ΔR/R over a large part of this field range. Both sets show larger fractional changes at higher temperatures. The apparent fractional temperature shifts are also given for typical resistors when used as thermometers.
Mirror-trapped potassium plasma with hot filament array
Authors: Kiwamoto Y.
Published: March 2003

An array of hot tungsten wires is used for surface ionization of potassium atoms introduced perpendicular to the magnetic field. The array is opaque to the neutral beam but is highly transparent to the axially flowing plasma. By placing it in a magnetic mirror configuration, well trapped ions are produced.
Dielectric spectroscopy at sub-audio frequencies—two techniques in comparison
Authors: Vallance Michael , Faith Don C. , Cooper Stuart L.
Published: March 2003

Two dielectric spectrometers for use at sub-audio frequencies have been designed around a digital microcomputer and data acquisition system. In one technique the driving signal and the current response are harmonic. In the other technique a current transient results from a voltage step. Comparison of the two techniques on real materials reveals good agreement between complex relative permittivity spectra. Moisture and electrode polarization aspects of specimen preparation are addressed.
Effective noise discriminator for use in acoustic emission studies
Authors: Sondergeld Carl H.
Published: March 2003

Both coherent and random short duration electromagnetic noise source pose serious problems to meaningful acoustic emission studies. A simple but effective discriminator is described which makes acoustic emission studies possible in severe noise environments. Additional circuitry is presented which permits one to eliminate coherent noise sources from the acoustic emission data.
High pressure apparatus for optical studies of liquids
Authors: Dawson Daniel R. , Offen Henry W.
Published: March 2003

A simple optical cell for high-pressure studies of liquids and solutions to 5 kbar, and used in the 0–60 °C temperature range, is described. Convenient methods for pressure measurement, temperature control and isolation of the sample from the pressure fluid are presented. This system is used to detect liquid-solid phase transitions in benzene and trans-decalin by scattered light measurements.
High-temperature, multi-atmosphere, constant stress compression creep apparatus
Authors: Carter C. H. , Stone C. A. , Davis R. F. , Schaub D. R.
Published: March 2003

The conceptual design and construction of an apparatus developed for deforming materials by subjecting them to constant compressive stresses at elevated temperatures is described. Sample loading and alignment procedures and performance capabilities are discussed. A computer controlled data acquistion, storage and manipulation system is also described.
Techniques for compressibility measurements on explosive materials using an opposed diamond-anvil optical cell
Authors: Brasch J. W.
Published: March 2003

A strain gage transducer system has been developed which functions as ’’electronic calipers’’ to measure changes in thickness of samples as they are compressed in an opposed diamond-anvil optical cell. Planimeter measurements on photomicrographs of the same samples determine area changes and ruby fluorescence techniques provide pressure measurements. These techniques permit direct volume change measurements to be performed in the diamond cell. Accuracies in v/vi of 1% or better provide experimental PVT data to assist in developing equation of state models for explosive materials.
Mass spectrometric studies of material evolution from magnetic liquid seals
Authors: Raj K. , Grayson M. A.
Published: March 2003

Evolution of ferrofluid contained in two vacuum rotary feedthroughs is studied for the first time by a time-of-flight mass spectrometer in order to provide information on the background material these seals introduce into a high vacuum system. The seals used diester and poly(phenyl ether) based ferrofluids. The rate of evolution of the diester was found to be of the order of 3×10−10 g/s and that of the poly(phenyl ether) was below the detection limit of the mass spectrometer, i.e., 10−10 g/s. The oxygen and water evolution, which are generally of prime interest in vacuum application, were found to be 10−9 g/s for both seals at 3,000 rpm. The feedthroughs were successfully employed in precision abrasion mass spectrometric experiments.
Use of a capacitively coupled marginal oscillator for contactless transient conductivity measurements
Authors: McElroy Robert G. C.
Published: March 2003

A marginal oscillator circuit is described. This circuit was developed for measuring slow photoconductivity kinetics in high resistivity semiconductors. In this measurement technique, the sample is the dielectric of a parallel plate capacitor. This arrangement is compared and contrasted with the alternative configuration where the rf energy is coupled into the sample inductively. The optimum sample parameters for the use of this method are response times in the range 10−5 to 102 s and resistivities from a few hundred to 105 ohm cm.
Single crystal filters for neutron spectrometry
Authors: Nieman H. F. , Tennant D. C. , Dolling G.
Published: March 2003

Measurements of the effective absorption coefficient μ have been made, for a range of neutron energies, of large single crystal specimens of quartz, silicon and sapphire, at 300 K and 80 K. The effectiveness of such filters is given by the ratio of μ for (unwanted) epithermal neutrons to that for the desired thermal neutron beam. Our results indicate that sapphire is significantly more effective than either quartz or silicon for a wide range of neutron energies.
Homodyne method for detecting asymmetric spectra
Authors: Asada O. , Inoue A. , Tsukishima T.
Published: March 2003

A homodyne method proposed for detecting asymmetric spectra encountered in scattering experiments is examined theoretically and experimentally. The experiments are carried out on a simulated electrical circuit, and the validity of the proposed method is demonstrated. Various kinds of error in spectra obtained by the proposed homodyne method are examined and identified.
Ion beamlet steering by aperture displacement in two-stage accelerators
Authors: Conrad J. R.
Published: March 2003

The steering of ion beamlets by aperture displacement in two-stage four-grid accelerators is examined using a model previously developed for single-stage three-grid accelerators with large acceleration-deceleration ratio. The analysis (which includes the second order effects of space charge and the effect of potential sag due to finite aperture radius) is shown to be in good agreement with experimental data from two-stage accelerators.
Measurements of velocity profiles of gas in a rapidly rotating cylinder
Authors: Tokoi H. , Ozaki N. , Harada I.
Published: March 2003

The azimuthal and axial velocity of the source-sink flow in a rapidly rotating cylinder were measured by using the back scattered mode of the laser-Doppler velocimeter. A rotating optical system was devised for measuring the gas flow with a high angular velocity of 5.2×102 rad/s. The incident laser beams were introduced into the cylinder through the rotating optical system which synchronously, but independently, rotating with the cylinder. The Doppler-shifted signal was observed from the light back-scattered by small paraffin mist particles of about 1 μm in diameter. The accuracies of the measurements were within ±5% for the azimuthal flow-velocity component and ±8% for the axial one. The E1/4 layers formed on the sidewall and the feed radius were clearly observed due to the small Ekman number E=2.2×10−5. The theoretical results (boundary layer theory and numerical calculation) agree quantitatively with the experimental ones, except in the case of the feed radius.
Light scattering cell for studying crystals under uniaxial stress
Authors: Čopič M. , Zgonik M. , Lavrenčič B. B.
Published: March 2003

We describe the construction of optical scattering cell which has been used for the Brillouin spectroscopy of ferroelastic KH3(SeO3)2. Using a pneumatic transducer, we were able to obtain uniaxial stress up to 18 MPa in a 4 mm cube sample. Temperatures down to liquid N2 and up to 60 °C are obtainable with the stability of 2 mK. The cell is constructed for 90 degrees scattering geometry and allows the use of index matching liquid.
Experimental technique for determining surface potential as a function of gate voltage of a MOS capacitor
Authors: Tonner Paul D. , Simmons John G.
Published: March 2003

In studies of the MOS system is usually desirable to know the surface potential as a function of the gate voltage. This paper presents two methods which allow the surface potential of MOS capacitor to be obtained directly as a function of gate voltage, under either quasiequilibrium or nonequilibrium conditions.
Recent assessment of the performance and accuracy of a chemiluminescent rocket sonde for upper atmospheric ozone measurements
Authors: Hilsenrath Ernest , Kirschner Peter T.
Published: March 2003

The chemiluminescent rocket ozonesonde utilizing rhodamine-B as a detector and self-pumping for air sampling has been improved. The instrument employs standard meteorological sounding systems and is the only technique available for routine nighttime ozone measurements above balloon altitudes. The chemiluminescent detector, when properly calibrated, is shown to be specific to ozone, stable, and of sufficient sensitivity for accurate measurements of ozone from about 65–20 km. An error analysis indicates that the measured ozone profiles have an absolute accuracy of about ±12% and a precision of about ±6%. Approximately 20 flights have been conducted for geophysical investigations, while additional flights were conducted with other rocket and satellite ozone soundings for comparisons. In general, these comparisons showed good agreement.
Apparatus for zeta potential measurement of rectangular flow cells
Authors: DePalma V. A.
Published: March 2003

The apparatus described in this paper is designed to measure the zeta potential of rectangular plates of materials. Additionally, this design permits exposure of the plates to protein solutions injected into an electrolyte flowing between the plates. The plates, separated by glass shims, form a rectangular flow cell that is readily disassembled after exposure, enabling a detailed surface chemical examination of the adsorbed protein. Zeta potentials are calculated with values from the ratio of the streaming potential to the differential pressure drop across the cell, using an expression for the rectangular flow cell derived in the course of this work. Modulated fluid flow conditions reduce the effect of electrical drift of the measuring electrodes. Zeta potential, as a function of salt concentration (for flow cells constructed from glass slides and quartz plates), is documented and compared with present values in literature.
Precise stimulus for the measurement of visual flicker sensitivity
Authors: Gander R. E. , Frecker R. C.
Published: March 2003

The stimulus described uses a high-output, red, light-emitting diode (LED) as a light source. The luminance of the LED is kept constant by solid state cooling under feedback control. A specially developed 16 °, soft-edge field target is presented to the observer through Maxwellian view optics with a 1.6 mm artificial pupil. An adjustable, three-point head restraint holds the observer fixed relative to the stimulus, which itself can be aligned with the observer in three dimensions. These adjustments are resettable to within ±0.5 mm for repeat sessions on one observer. A two-alternative forced choice paradigm is used in conjunction with a modified staircase method of limits under on-line computer control. The stimulus is presently being used in a clinical research facility in the investigation of psychoactive drugs effects on flicker sensitivity.
Microsphere thermal deformeter
Authors: Koo Jackson C.
Published: March 2003

We have developed a highly sensitive thermal deformeter for measuring submicron variations in the dimensions of glass microspheres as a function of temperature. This allows us to determine the maximum temperature at which these microspheres can be DT (deuterium and trituium) filled through permeation without nonreversible deformation in the preparation of inertial confinement fusion targets.
Analytical design of the constant-stress cam lever
Authors: Arrowood Roy , Mukherjee A. K.
Published: March 2003

A suitably shaped cam lever permits creep testing of polycrystals under constant stress rather than constant load. The usual procedure for designing the cam lever is a graphical method, or an equivalent computational scheme. This paper derives simple analytical formulas for the cam lever shape.
Rotary-valve gas pulser
Authors: Madson J. M. , Theby E. A.
Published: March 2003

A rotary-valve gas pulser that produces a pulse-modulated seedant gas for mixing with a steady flow carrier is described.
New application of the Kelvin method involving the scanning of the bucking voltage
Authors: Ritty B. , Wachtel F. , Ott F. , Manquenouille R. , Donnet J. B.
Published: March 2003

A new technique is described pertaining to the Kelvin method and involving the scanning of the bucking voltage. In addition an automatic data acquisition system has been applied, thus improving its sensitivity and reliability, particularly when a small area reference electrode is used. Moreover, in contrast with what is usually the case in every null method, the calculation of the error is entirely free of ambiguity.
Interface for rapid data transfer from NIM counters to small computers
Authors: Person James C. , Nicole Paul P.
Published: March 2003

The advantages of using two parallel input/output ports to interface a small computer to the Ortec counter print loop are discussed.
70 kW high repetition rate laser exciter
Authors: Karny Ziv , Rotstien Anatol , Chuchem David , Milanski Israel S.
Published: March 2003

A high average power pulser rated at 70 kW of electrical power is described. The innovative feature of this pulser is a saturable charging inductor which provides for a more rapid charging time without compromising thyratron recovery.
Automated system for low loss dielectric measurements under pressure
Authors: Farzaneh M. , Destruel P.
Published: March 2003

We describe here an automated system for dielectric measurements under pressure at high frequency. This system is governed by a Commodore micro-computer type P.E.T. 2001. The advantage of this equipment is to prevent any error due to operators in the measurement procedure and consequently to increase the accuracy of measurement.
Endoscopic system for simultaneous visual examination and electronic detection of fluorescence
Authors: Kinsey J. H. , Cortese D. A.
Published: March 2003

A sensitive parallel system for visual examination of a target area with simultaneous detection and measurement of fluorescent emission from the same region is described. This device, originally designed and constructed for bronchial cancer detection, alternates visual illumination and narrow band excitation radiation in conjunction with a synchronously shuttered PMT at frequencies above the visual flicker fusion threshold to provide parallel operation. The signal from the PMT is synchronously amplified using a lock-in amplifier, the dc output of which is voltage-to-frequency converted and amplified to provide an audible tone whose frequency is proportional to the fluorescence sensed.
Method for precise balancing of a radio frequency bridge in wide line nuclear magnetic resonance spectrometer
Authors: Szczurek T. , Wieczorek J. , Gutsze A. , Hunger M.
Published: March 2003

A wide line NMR spectrometer working at 12 MHz has been constructed. The spectrometer employs an rf bridge based on a hydrid junction. Precise balancing of the bridge is performed by means of varicaps and a dc heated electric bulb as the variable reactive and active elements respectively.
Improved spherical electrical feedthroughs for high-pressure, nonambient temperature vessels
Authors: Vassiliou John K. , Jamieson John C.
Published: March 2003

An improved version of the ball and ball seat method using the plastic Kapton is presented for sealing electrical leads in hydrostatic 1 GPa vessels. Tools and method for the manufacture of such seals are presented. The seals may be exposed to nonambient temperatures ranging from 80–400 K according to the experimental needs.
Production of pulsed electric fields using capacitively coupled electrodes
Authors: Kendall B. R. F. , Schwab F. A. S.
Published: March 2003

It is shown that pulsed electric fields can be produced over extended volumes by taking advantage of the internal capacitances in a stacked array of electrodes. The design, construction, and performance of practical arrays are discussed. The prototype arrays involved fields of 102–103 V cm−1 extending over several centimeters. Scaling to larger physical dimensions is straightforward.
Dual-variable detection method providing a wider dynamic range to a photomultiplier
Authors: Hayashi Hidechika , Tachibana Hideki , Wada Akiyoshi
Published: March 2003

The dual-variable detection method is a device to provide a wider dynamic range to the light intensity measurement by a photomultiplier. A dynamic range as wide as seven orders of magnitude is attainable by controlling and analyzing both the dynode voltage and the anode current. The electronic circuit is illustrated and its application to the simultaneous measurement of the absorbance and the circular dichroism, which have used to require different light intensity range for the optimum operation, is described.
Laser beam manifold and particle photography system for use in fluid velocity measurements
Authors: Owen Robert B. , Campbell C. Warren
Published: March 2003

A laser beam manifold and particle photography system has been developed for use in fluid velocity measurements. The laser manifold is a device which transforms a single laser beam into several uniform parallel beams. By orienting two manifolds mutually perpendicular, an optical grid can be formed which acts as a reference for fluid velocity measurements. This optical grid is for all practical purposes totally nonperturbing to the flow. Tracer particles moving in the plane of the grid are then photographed to yield fluid velocities that can be measured relative to the optical grid. System construction and theory are presented.
Continuous void swelling measurements using fission fragment irradiation
Authors: Lefakis H. , Blewitt T. H. , Birtcher R. C.
Published: March 2003

A new simulation technique has been developed for the study of void swelling. Its salient characteristics include the use of fission-fragment irradiation produced by doping with 235U and irradiating in a thermal neutron flux; use of bulk specimens and the yield of continuous, in situ swelling data. This technique has several unique advantages and, in conjunction with other conventional methods, it offers the possibility of detailed evaluation of void nucleation and growth theories. Preliminary results for low-dose void swelling in Ni at 500°C are presented.
Rapid nondestructive technique for monitoring polishing damage in semiconductor wafers
Authors: Sopori B. L.
Published: March 2003

A rapid nondestructive (optical) technique, which can be used to monitor directly the chemical polishing/etching time required for removal of lapping (or sawing) damage in semiconductor wafers, is described. This technique utilizes dependence of the amplitude of surface photovoltage signal on the residual surface stress to determine the ’’end-point’’ of chemical polishing/etching. It is shown that this technique is very sensitive and well suited for large scale polishing facilities.
0.1 ppm four-terminal resistance bridge for use with a dilution refrigerator
Authors: Edmunds D. L. , Pratt W. P. , Rowlands J. A.
Published: March 2003

Measurement of electrical resistance of pure metal samples at low temperatures poses special problems because the resistance is usually very small and must be measured very precisely to be useful. We present a tested design for a bridge which in several significant respects is superior to previous ones. At ultralow temperatures it permits the measurement of resistance to 0.1 ppm in resistors from ∼1 mΩ to 0.1 μΩ, or lower. Indeed, relatively high precision measurements can be made over the whole temperature range from ∼20 mK to near 7 K. Finally, a new technique is developed which eliminates most of the problems of making a comparison (or standard) resistor and at the same time eliminates the necessity of an extrapolation to zero temperature in order to obtain ρ0, as is conventionally done.
Self-crowbarring, load-isolating triggered spark gap
Authors: Robinson James W.
Published: March 2003

Crowbarring is achieved when a magnetically driven arc contacts an electrode in the crowbar circuit. No auxiliary timing circuitry is required and, at the time of crowbarring, the arc divides into two parts such that the load is isolated from the source. A discharge which peaks at 200 kA in 4 μs is crowbarred and displays a 50-μs e-folding time with a ripple current of less than 5%. Main switching and crowbarring are combined in a single 3-electrode spark gap which is triggered by a pin between two of the electrodes. Crowbar timing is insensitive to gap dimensions and to current magnitude. Pin placement is critical but little energy is dissipated in the neighborhood of the trigger pin.
Rogowski coil for measuring fast, high-level pulsed currents
Authors: Pellinen Donald G. , Di Capua Marco S. , Sampayan Stephen E. , Gerbracht Harold , Wang Ming
Published: March 2003

This paper describes the theory and design of Rogowski-wound coils used to measure nanosecond electrical curent pulses in the megampere range. The coils have risetimes of less than one nanosecond, microsecond decay times and typical sensitivities in the range of 10−3 to 10−4 V A−1. They operate in large radiation fields, under intense electron bombardment and at high rates of current rise.
Analysis of the spiral generator
Authors: Rühl F. , Herziger G.
Published: March 2003

The output voltage of spiral generators, which are used for high voltage pulse generation, is derived analytically from a coupled wave analysis that includes the switch impedance, loading of the output terminals, and the influence of the finite conductivity of the spiral-wound conductors. It is demonstrated that the spiral generator behaves like a damped LC resonance element which is charged by a fraction of the switch current. Graphs of the output voltage as function of dimensionless parameters and scaling relationships for spiral generators are given.
Design and development of the coaxial duoPIGatron ion source
Authors: Horiike Hiroshi , Akiba Masato , Arakawa Yoshihiro , Matsuda Shinzaburo , Sakuraba Junji
Published: March 2003

A new variation of a duoPIGatron ion source, named coaxial duoPIGatron has been proposed and designed. This ion source has a magnetic center pole in the intermediate electrode, thereby feeding ionizing electrons widely to the arc chamber. The first model had produced a source plasma of excellent uniformity, but the density level was low presumably due to leakage or bridging magnetic flux in the cathode plasma region. Numerical calculations have been performed on the magnetic field structure for several shapes of the intermediate electrode with center pole. The source was designed and constructed on the basis of these numerical results and was tested experimentally. It was confirmed that the primary electrons were fed widely to the PIG chamber along the spreading magnetic lines of force, and they produced a uniform source plasma with high density. Thus the concept of hollow feeding of electrons has proved its applicability to an ion source of larger beam extracting area.
La–Mo emitters in hollow cathodes
Authors: Goebel D. M. , Forrester A. T. , Johnston S.
Published: March 2003

A hollow cathode which utilizes lanthanum molybdenum (LM) as the active electron emitter is described and compared in performance to a LaB6 emitter of equal area in an identical configuration. Tests in both argon and hydrogen produced effective emission current densities of up to 10 A/cm2 from the LM material in continuous and long pulse operation. Examination after 40 h running time showed no sign of damage or rapid evaporation. Impurity build up on the emitting surfaces which stopped the LaB6 emission after 50 h was not apparent with the LM and long lifetimes are anticipated for cathodes using this emitter.
Device for deformation-free electrolytic etching of thin specimens
Authors: Weerheijm H. , de Keijser Th. H. , Meijer H. D. F.
Published: March 2003

An easily constructed device is described that ensures deformation-free electrolytic etching of thin (μm range) specimens and avoids elaborate and time-consuming procedures. Essentially the device consists of a perforated electrode on which the specimen is held by maintaining a low pressure underneath. In addition the description of a valve assembly is given which is used for the recycling of the electrolyte that is sucked out of the bath through the holes in the electrode.
Adapting a displex closed-cycle helium refrigerator for ultrahigh vacuum operation
Authors: Fowler G. L. , Panitz J. A.
Published: March 2003

A modification of a commercial closed-cycle liquid helium refrigerator is described which permits operation at pressures below 10−9 Torr. By using a sapphire insulator on the low-temperature stage, and incorporating vacuum-compatible heating elements, samples can be biased to ±30 kV over a temperature range of 15–300 K.
Chemical lathe for the efficient preparation of high-quality surfaces for low-cycle fatigue
Authors: Bober Henry T. , Quesnel David J.
Published: March 2003

This paper describes a chemical lathe for the efficient preparation of high-quality surfaces on samples for low-cycle fatigue testing. The chemically machined gage lengths of samples prepared by this unit are of metallographic quality and free of machining marks and residual stresses. This paper discusses the theory of operation, design, construction, and setup of the chemical lathe. The basic concept of this unit may be readily applied to a variety of specimen geometries employed in other mechanical tests.
Carbon plasma gun
Authors: Mendel C. W. , Zagar D. M. , Mills G. S. , Humphries S. , Goldstein S. A.
Published: March 2003

A family of plasma guns supplying highly ionized carbon plasma is described. The guns are simple and inexpensive to construct and are pulsed by small capacitor banks of a few hundred joules. The output consists of 1017–1018 multiply ionized carbon ions traveling at about 107 cm/s. Neutral output is very low and arrives well after the ionized carbon. The guns and pulsers are very reliable.
Capacitively-coupled inductive sensors for measurements of pulsed currents and pulsed magnetic fields
Authors: Ekdahl C. A.
Published: March 2003

In experiments involving pulsed high magnetic fields the appearance of the full induced voltage at the output terminals of large-area inductive sensors such as diamagnetic loops and Rogowski belts imposes severe requirements on the insulation near the output. Capacitive detection of the inductive-sensor output voltage provides an ideal geometry for high-voltage insulation, and also accomplishes the necessary voltage division. An inductive-shunt current monitor was designed to utilize the capacitive-detection principle. The contruction of this device and its performance are described in this paper.
Synchronized actively mode-locked short pulse ruby laser
Authors: Martin F. , Grek B. , Pépin H.
Published: March 2003

An actively mode-locked, Q-controlled ruby laser has been developed which produces high-intensity (1.5 GW/cm2) 35 ps pulses synchronized to better than 100 ps with an event produced by another mode-locked laser.
Simple laser power-monitor for use with moderate power infrared lasers
Authors: Hendricks Lloyd J.
Published: March 2003

A simple, inexpensive yet reliable power monitoring device for power levels of 1–10 W in the infrared is described. The monitor uses a thin foil of refractory material to convert the infrared radiation to visible radiation, where the power may be determined by a conventional visible light photometric device.