bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-temperature thin graphite film thermometers
Authors: Dodson B. , Low T. , Mochel J.
Published: March 2003

Thin films of colloidal graphite (typically 1 μm), applied in spray aerosol form, have been tested for use as thermometers below 4 K. These thermometers are easily fabricated, have good low-temperature stability, an estimated heat capacity of 0.25 erg/K cm2 at 3 K, and a thermal relaxation time limited only by the properties of the substrate.
Zener diode dosimeter
Authors: Tomimasu T. , Yamazaki T. , Mikado T.
Published: March 2003

The nature of electron-induced changes in the electrical properties of Zener diodes and their application to a Zener diode dosimeter are presented. A standard Zener diode is used as a small size (0.15×0.4×0.4 mm), high-level dose detector. The irradiated dose can be estimated by a shift of the breakdown voltage of the Zener diode. The distinct advantages of its small size and superior resistance to radiation damage enable us to measure the cross-sectional profile of the high-intensity electron beam from a linac with high spatial resolution of about 0.4 mm.
Instrument for vacuum ultraviolet fluorescence lifetime measurements
Authors: Lyke Richard L. , Ware William R.
Published: March 2003

An instrument is described for measuring fluorescence lifetimes, fluorescence excitation spectra, and relative fluorescence quantum yields by photon counting in the vacuum ultraviolet. The temporal resolution is satisfactory down to lifetimes of 200 psec, and the sensitivity permits measurements on totally absorbing samples with quantum yields as low as 10−4. The nanosecond H2 flash lamp is a satisfactory source for these measurements with a useful range from 120 to 400 nm.
Influence of technology on the metrological properties of gold–chromium alloy pressure gauges
Authors: Bock Wojciech J. , Wiśniewski Roland
Published: March 2003

This paper discusses the technological processing of the gold–chromium (with 1.95±0.05% Cr) alloy pressure gauge, optimized to get the best metrological properties. It also presents experimental results of thermal and pressure measurements of the alloy. It was found that the Au–Cr pressure gauge, properly seasoned in the controlled seasoning process, is completely free of hysteresis in resistance due to pressure changes, with uncertainty of less than 0.4 bar in 6000 bars range. Resistance-pressure and resistance-temperature characteristics didn’t change during the pressure or temperature cycling. It is also shown in the paper that there is a possibility of employing Au–Cr pressure gauges for measurements of high pressures up to about 20 000 bars.
Wall shear stress measurement with a hot film in a variable temperature flow
Authors: Reichert J. K. , Azad R. S.
Published: March 2003

Although the calibration of the flush-mounted hot film device was affected by changes in the probe elevation temperature of as little as 1 °C, it was possible to use the probe over a considerable range of elevation temperature by appropriate calibration. The behavior of the calibration coefficients with changing elevation temperature has been documented. The general probe behavior presented by Bellhouse and Shultz was substantiated and extended to a wider range of operating conditions. The experience with the mounting system designed for the probe has suggested how to obtain an improved design to maintain the probe calibration. Sensitive measurements of the wall shear stress in developing turbulent pipe flow have been taken with the probe calibrated for flow temperature changes. These appear to be consistent with trends observed by others in developing duct flow.
Interfacing a pulsed nitrogen laser with electro-optic instrumentation of higher frequency
Authors: Switzer William L. , McCullen W. L. , Schreiner A. F.
Published: March 2003

The details of design and construction are given of an electronic delay trigger which makes it possible to use pulsed (ν0) nitrogen lasers with electro-optic instrumentation with modulation frequencies in excess of the laser pulse frequency, ν0.
Improved circular dichroism instrument in the vacuum ultraviolet
Authors: Gross K. P. , Schnepp O.
Published: March 2003

The vacuum ultraviolet circular dichroism instrument developed in this laboratory and originally described in 1970 has been modified and improved. The principal modification is the replacement of two lenses by a collimating mirror, thus converting to reflection optics. As a result, the efficiency of the instrument was considerably improved; particularly at wavelengths shorter than 160 nm. The effectiveness of the polarization optics at short wavelengths was investigated and found to be unimpaired out to 135 nm.
Extrusion rheometer for characterizing thixotropic materials
Authors: Hodgetts G. B. , Freestone A. R. I.
Published: March 2003

A special form of extrusion rheometer has been developed for characterizing thixotropic pastes and high viscosity materials. It consists of a cylinder with an orifice situated halfway along, and has a piston at each end. In use, a sample plug of material is forced through the orifice at a uniform rate by one of the pistons, and the load required is recorded. After a given recovery period the material is forced back through the orifice by the other piston, and the load again recorded. If the material is thixotropic, it will have a reduced viscosity on the second ’’pass,’’ and the percentage reduction in load will be related to the thixotropy of the sample. This rheometer was developed for testing resin adhesive pastes, but other possible applications might include the testing of paints, foodstuffs, cosmetics, toothpaste, printing inks, and greases.
Thermal cycling apparatus to test germanium thermometer stabilities
Authors: Plumb H. H. , Besley L. M. , Kemp W. R. G.
Published: March 2003

Apparatus has been developed for thermal cycling germanium thermometers from ambient temperatures to 20.280 K and evaluating their reproducibility at the lower temperature. Gaseous and liquid helium are drawn from a storage Dewar into refrigerators loosely attached to a shielded and insulated enclosure initially at room temperature. Cooling the enclosure requires 5 h; heating it up to room temperature afterwards, 7 h. The existing apparatus accommodates 30 germanium thermometers and a reference standard platinum resistance thermometer. Because digital voltmeters can be used effectively, most of the data collection is automated and statistical analysis of the data is performed in minutes. Experiments have demonstrated that the standard deviation of 11 series of measurements (no thermal cycling) is the equivalent of 0.04 mK for an average thermometer at 20.280 K. The apparatus is being employed to determine the stability of the 30 thermometers during a 100-cycle test.
Carbon and graphite monofilaments as in-line electron beam energy monitors
Authors: Keller D. V. , Rice D. A.
Published: March 2003

Carbon and graphite monofilaments have been evaluated for in-line diagnostics of pulsed relativistic electron beams used in testing the dynamic thermomechanical response of materials. The monofilaments are small enough to have negligible effect on the electron beams. This newly developed technique is capable of specific energy measurements from a few calories per gram to more than 1200. The measurement is made within a few microseconds, eliminating any need for time extrapolation to account for heat loss and permitting measurement before the active filament is destroyed by blowoff debris from spall or vaporization of adjacent material.
Magnetic resonance signal-to-noise calculation: direct vs lock-in recording
Authors: Conradi Mark S.
Published: March 2003

The signal-to-noise ratios (S/N) of magnetic resonance lines using two methods of post-spectrometer signal processing are compared. These methods are the direct method, which records the resonance line shape itself, and the lock-in method, which records its derivative. The S/N of the resonance line, its derivative, and its integral are derived for both methods. Calculated S/N for the two methods are substantially the same for the derivative of the line, but are better for the direct method for the line itself and its integral. Practical experimental considerations concerning the two methods are discussed.
Miniature plane mirror analyzer suitable for angle-resolved photoelectron spectroscopy
Authors: Smith N. V. , Larsen P. K. , Traum M. M.
Published: March 2003

A plane-parallel-plate electron energy analyzer is described based on the second-order-focusing 30° injection geometry. The small size of the analyzer permits it to be attached to a commercial rotary feedthrough and to be used in angle-resolved photoemission studies. The analyzer is operated in a constant pass energy mode, and the electron energy spectrum is obtained by sweeping the voltage on a preretardation/acceleration stage. A resolution function ΔE/E equal to ∼6% leads to a resolution of lower than 0.2 eV at sufficiently low pass energies. The performance is illustrated with results obtained using synchrotron radiation in a system having two identical analyzers.
Low-noise voltage-sensitive preamplifier with output stabilization by pole-zero cancellation in the feedback circuit
Authors: Kopp M. K. , Williams J. A.
Published: March 2003

Low-noise, voltage-sensitive preamplifiers were designed with pole-zero cancellation in the feedback circuit to stabilize the output baseline against variations in the mean rate and amplitude of random signals. Compared to conventional feedback and subsequent pole-zero cancellation, this method of baseline stabilization increased the fraction of signals transmitted without distortion by preamplifier saturation from 50 to ≳99% for steplike input signals of 240 mV amplitude occurring randomly at a mean rate of 104 signals/sec.
Liquid helium-cooled MOSFET preamplifier for use with astronomical bolometer
Authors: Goebel John H.
Published: March 2003

A liquid helium-cooled p-channel enhancement mode MOSFET, the 3N167, is found to have sufficiently low noise for use as a preamplifier with helium-cooled bolometers that are used in infrared astronomy. Its characteristics at 300, 77, and 4.2 K are presented. It is also shown to have useful application with certain photoconductive and photovoltaic infrared detectors.
Field-widened Michelson interferometer for measuring velocities of diffuse back surfaces of shocked specimens
Authors: Bailly-Salins R.
Published: March 2003

A classical Michelson spectrometer with different length arms used to study the velocity of a diffusing surface illuminated by a laser beam gives a signal whose modulation M decreases rapidly with increasing sensitivity of the apparatus and roughness of the surface. Using the Fraunhofer diffraction theory, a formula connecting these parameters has been established. It proves the advantage of the field-widened interferometer, and we have set up an original specimen where M=1 provided that all the points of the illuminated area move at the same velocity. For a disordered displacement of these points, the signal of this interferometer is more complicated; a particular case is solved and experimentally verified in connection with the free surface velocity of a fixed aluminum disk submitted to the impact of a thin plate projected with inaccurate parallelism.
Application of the Hall effect to the switching of inductive circuits
Authors: Inall E. K. , Robson A. E. , Turchi P. J.
Published: March 2003

Experiments are described in which the application of a pulsed magnetic field to a Corbino disk of indium antimonide causes an increase in resistance of about 2 orders of magnitude in a time of 5 μsec. The use of this element as a switch for the transfer of energy from an inductive energy store is discussed.
Video observation of a torsion pendulum
Authors: Gates A. S. , Edwards J. G.
Published: March 2003

A video camera, recorder, and monitor were used to record and observe the motion of a dynamic torsion–effusion pendulum. The operator was free to tend to the conditions of the experiment; data from the pendulum were obtained subsequently from the video record. Results are presented from a test of the method with no effusion occurring.
Time-dependent and thermal history effects in low temperature glass–ceramic capacitance thermometers
Authors: Swenson C. A.
Published: March 2003

The low temperature (4.2–45 K) calibrations of two commercial capacitance thermometers show drifts toward equilibrium values both when held at 4.2 K immediately after cooling from 77 K, and when subsequently warmed to higher temperatures. Irreproducibilities of up to 0.2 K in the equilibrium calibrations were traced to differences in the thermal history of the sensors.
15 cm duoPIGatron ion source
Authors: Stirling W. L. , Tsai C. C. , Ryan P. M.
Published: March 2003

The 10 cm (grid diameter) duoPIGatron ion source produces pulsed hydrogen ion beams of 10–15 A beam current in the 20–40 keV energy range for a duration of a few tenths of a second. To fulfill the requirement of the next generation of high-power neutral beam injectors for heating plasmas in CTR devices, this source has been enlarged to a version 15 cm in grid diameter. In addition, by utilizing a magnetic multipole line cusp field confinement method, the plasma created is characterized over the 15 cm grid diameter by a noise level within ±10% and spatial density variations within ±5% at a density on the order of 1012 cm−3. This larger source has operated reliably and produced a beam current exceeding 30 A of hydrogen at 27 keV. Initial operation of a 20 cm version of this source employing line cusp confinement has produced an extraction current of 60 A at 33 keV.
Comparison of techniques for extracting signals from a strong background
Authors: Arsenault H. H. , Marmet P.
Published: March 2003

The useful data from experiments are sometimes superimposed on a large-amplitude, slowly changing continuum that masks the information of interest. Techniques for extracting the information are analyzed and compared. We show that the processing comprises a tradeoff between removal of the continuum and detectability, distortion, and the signal-to-noise ratio of structures. It is found that wide structures are the hardest of all to extract without distortion and with a good signal-to-noise ratio, and that for a given set of experimental parameters, there is a limit to the class of structures that may be extracted from the data.
LED marine beam transmittance meter
Authors: Basano L. , Ottonello P. , Papa L.
Published: March 2003

In this paper we present a beam transmittance meter for measurements of turbidity in situ, which employs a LED (light emitting diode) as the light source. The electronic modulability of LEDs makes the whole modulation device extremely simple. Thanks to the aforesaid modulation,, which in good transmissometers is obtained by mechanical chopping, synchronous detection of the signal is made possible. The instrument is very sensitive, stable, and low cost.
High sensitivity nuclear acoustic resonance spectrometer incorporating a new calibration technique
Authors: Franz Judy R. , Mullen M. E.
Published: March 2003

A new type of nuclear acoustic resonance spectrometer with a sensitivity approximately two orders of magnitude greater than standard cw transmission spectrometers is described. A new technique for calibrating the sensitivity of ultrasonic spectrometers is also described. The calibration procedure can be carried out concurrently with experimental measurements when working with metal samples.
Construction of supported fission foils for laser excitation
Authors: Kerley T. M. , McArthur D. A. , Sasmor D. J.
Published: March 2003

A procedure is described for making smooth, durable coatings of uranium oxide (∼5 μm thick) on ceramic substrates such as alumina and beryllia. The coatings have shown no damage after being excited repeatedly to ∼1020 fissions/m3 with a thermal neutron pulse ∼150 μsec wide. The uniformity of fission fragment energy emission from the coatings has been measured and the coating structure has been studied with electron microscopy.
Field sweeper and recorder drive for de Haas–van Alphen type phenomena
Authors: Long Jerome R. , Batra Narendra K.
Published: March 2003

A collection of simple circuits using inexpensive integrated components has been developed for the purpose of obtaining slow, high-resolution magnetic field sweeps for study of de Haas–van Alphen and related effects with the option of either sweeping the field or driving a recorder at a rate inversely proportional to the field.
Compact fast-acting shutter for a multiple-position, planetary workholder
Authors: Bates B. , McCartney D. J. , Moore D. , Noble S. McC.
Published: March 2003

A compact shutter system for a vacuum coating plant is described which has simultaneous operation on three substrate positions on a planetary workholder. The shutter is located close to the substrate surfaces and can be fully opened in approximately 0.2 sec and closed in less than 0.1 sec.
Coaxial cables as feedthroughs for high-vacuum and low-temperature applications
Authors: Thompson J. R. , Thomson J. O.
Published: March 2003

The adaptation of small, commercially available coaxial cable for use as a vacuum feedthrough to a low-temperature apparatus is described.
Locking millimeter wavelength klystrons with a digital phase-frequency detector
Authors: Pickett Herbert M.
Published: March 2003

Modification of the phase detection circuit of a commercial phase-lock synchronizer is described. The new phase detector is a digital phase-frequency discriminator. The locks obtained with a millimeter wavelength klystron using this modification are much easier to obtain and are much more stable. In addition, phase locking is obtained only for one of the sidebands formed by mixing the klystron with reference source.
Self-supporting thin films—parting agent
Authors: Arakawa E. T. , Chung M. S. , Williams M. W.
Published: March 2003

To produce self-supporting thin films a substrate must be coated with a parting agent before the sample material is vacuum deposited on the substrate. We describe a spin-coating method which is simpler, faster, and more reliable than our previous methods of applying the parting agent.
Simple design of a high-temperature oxidizing furnace for integrated optics processing
Authors: Pastor A. C. , Tangonan G. L.
Published: March 2003

The design of a simple high-temperature oxidizing furnace is shown. This furnace has been useful in integrated optics waveguide formation in LiNbO3 and LiTaO3 by the techniques of metal in-diffusion and epitaxial growth by melting (EGM). The principal advantages of this design are direct observation of the sample during processing, high-temperature operation (up to 1500°C has been demonstrated), and low materials cost.
System employing laser heating for the measurement of high-temperature properties of materials over a wide pressure range
Authors: Whittaker A. Greenville , Kintner P. L. , Nelson L. S. , Richardson N.
Published: March 2003

An equipment system is described that can be used to obtain high-temperature physical property data on refractory materials by means of laser heating. Properties that can be measured are the vapor pressure of solid and liquid phases, the relative rate of vaporization, and emission spectra from solid and vapor phases. Solid phases can be studied by splat-cooling of the liquid and quench-cooling of the solid and vapor. Temperature can be measured both pyrometrically and spectroscopically. In addition, the effects produced by heating a material in an atmosphere of controlled composition and pressure can be studied.
Plasma studies on a duoPIGatron ion source
Authors: Tsai C. C. , Stirling W. L. , Ryan P. M.
Published: March 2003

In an effort to develop a plasma source capable of producing a dense, quiescent, uniform plasma for extracting tens of amperes of hydrogen ions, experimental and theoretical studies on a duoPIGatron ion source have been pursued. A study of plasma generation in the duoPIGatron was begun and a discharge model was subsequently developed to explain observed source behavior. The discharge model is based on two plasmas, a cathode plasma and a PIG plasma separated by a double layer of ions and electrons, and is similar to the existing model for a duoplasmatron. This discharge model is reviewed and the importance of the double layer on plasma generation in the duoPIGatron is discussed. Source electrode modifications suggested by the model resulted in a low noise level of about ±5% and a low-denisty nonuniformity of about ±10% over a 10-cm diameter at a high hydrogen plasma denisty of roughly 2×1012 cm−3. This source has been operated reliably to produce a hydrogen ion beam of 15 A at 40 keV. Initial operation of a 20-cm source employing magnetic multipole line cusp confinement [W. L.,Stirling, C. C.,Tsai, P. M.,Ryan, Rev. Sci. Instrum. 48, 533 (1977)] has delivered a beam of 60 A at 33 keV.
Integrated circuit Robinson oscillator for NMR detection
Authors: Deschamps P. , Vaissiére J. , Sullivan N. S.
Published: March 2003

A simple, compact, broadband, level-limited oscillator using integrated circuits is described for the detection of NMR absorption throughout the frequency range 1–70 MHz for rf levels of 1–100 mV.
Surface acoustic wave probing with spaced interdigital transducers
Authors: Bond W. L. , Fortunko C. M. , Quilici S. L. , Shaw H. J. , Souquet J.
Published: March 2003

We have found that interdigital surface acoustic wave (SAW) transducers deposited on glass substrates and positioned very close to a piezoelectric crystal delay line surface (’’spaced transducers’’) may be used to simulate identical transducers fabricated directly on the surface, for pretesting and prealignment of SAW devices. A novel spaced transducer mounting technique has been developed that utilizes a free floating gimbal, which permits positioning the spaced transducer substrate next to the delicately polished SAW substrate without any mutual wiping. This feature greatly extends the reliability of the spaced transducer and overcomes the problem of damaging the surface polish. The gimbal mechanism is mounted on a mobile support which ensures good positioning and orientation accuracy. A number of important uses for the new spaced transducer configuration in connection with surface acoustic wave delay line simulation are described, and a brief treatment of the electrical and coupling properties of spaced transducers is also presented.
Apparatus for measuring the thermoelectric power of thin film and bulk samples
Authors: Shen Y. R. , Leonard W. F. , Yu H. Y.
Published: March 2003

An apparatus for measuring the thermoelectric power (TEP) of bulk and thin film materials is described. Spring tension-welded thermocouple probes are used to make electrical contact with the sample surface. The apparatus is small, simple, and can be used under different environmental conditions at various temperatures. It is also designed so that the sample can be easily and quickly mounted and removed. Measurements taken on n-type and p-type bulk Bi2Te3 samples and a thin copper film are reported. The effects of sample thickness and surface conditions on the measured TEP values and criteria for minimizing errors are discussed.
’’Forgiving’’ lens for angular-dependent electron spectrometry
Authors: Best P. E.
Published: March 2003

It is shown that a tube–aperture lens has desirable properties as a retardation or acceleration element in angular-dependent electron spectrometry.
Phaser for lock-in null detectors
Authors: Work Richard N.
Published: March 2003

A motor driven, three-terminal capacitor introduces a small, periodic unbalance of low frequency and zero average deviation into the output of a transformer bridge. Presence of the resulting signal in the output of the lock-in demodulator permits easy adjustment of the reference phase without the need of disturbing bridge settings or the detector sensitivity.
Clipping level dependence of the photon count autocorrelation amplitude from Gaussian–Lorentzian light
Authors: Nieuwenhuysen P. , Clauwaert J.
Published: March 2003

Experimental results are presented for the clipping level dependence of the photon count autocorrelation amplitude from Gaussian–Lorentzian light. These show temporal and spatial integration effects, as predicted by theory, which hinder the application of the clipping gate test for digital clipped correlators by Chen et al. [Rev. Sci. Instrum. 46, 1356 (1975)].
Designing tapered anvil apparatus for achieving higher pressures
Authors: Bundy F. P.
Published: March 2003

An analysis is made for tapered anvils of ultrahigh-pressure apparatus in terms of the loading distribution on the face and flanks that would generate stress fields within the body of the anvil which are within the strength capability of the anvil material. To attain the highest possible face pressures the hardest and strongest materials must be used for the anvils, and in addition, the pressure of the gaskets against the tapered flanks must follow a proper gradient. The pressure performances of various actual apparatuses are presented to compare with the suggestions of the analysis. Using diamond anvil material together with optimum gasket geometry and structure it seems that useful apparatus pressures as high as one megabar (105 GPa) are possible.
High-temperature x-ray topography system for the investigation of semiconductor single crystals
Authors: Hastenrath M. , Krüger H. E. , Kubalek E.
Published: March 2003

A high-temperature x-ray topography (HT–XRT) system is described which allows the in situ investigation of temperature-induced defect generation in single crystals. The system is especially designed for the simulation of usual annealing processes in commercial HT furnaces, and it is shown that radial temperature gradients during heat cycling are comparable. The actual HT furnace is capable of continuous operation at temperatures exceeding 1700 K and is suited for experiments under vacuum better than 10−8 Torr as well as for inert gas flow or gas excess pressure. The system allows recording of specimen areas of 50 mm2 within 1 min with a resolution better than 15 μm. Application to the investigation of the creation, multiplication, and movement of single dislocations during the annealing of silicon wafers is demonstrated in a series of in situ topographs.
Thoriated tungsten hairpin-filament electron source for high- brightness applications
Authors: Murray R. G. , Collier R. J.
Published: March 2003

A carburized 2% thoriated tungsten hairpin-filament electron source, 0.125 mm in diameter, which operates at 10 kV with a brightness level of 5×104 A cm−2 sr−1 and has a rated life time of ≳700 h is described. The operating temperature of ∼1900 K (optical) is about 800 K below that of plain tungsten for the same brightness, and accounts for the order-of-magnitude increase in life. Methods for obtaining the required vacuum environment and carrying out the carburization are discussed.
New biasing elimination method for laser-Doppler velocimeter counter processing
Authors: Hoesel W. , Rodi W.
Published: March 2003

A new method is introduced for correcting the biased statistics of measurements with laser-Doppler velocimeters operating in the individual realization mode and using counters for signal processing. Two variations of the new correction method are proposed. One is suitable for all uniformly seeded flows; prior to averaging, the individual velocity measurements are weighted with the corresponding residence time of the seed particles in the probe volume. The other variation is suitable for flows with nonuniform seeding in which the average particle separation time is small compared with the time scale of the turbulent fluctuations, and in this method the particle separation time is used to weight the individual measurements. In both cases, a large number of samples is required. An experimental setup for realizing the new biasing correction method is described for each variation. The residence-time weighting method is applied to mean-velocity measurements in a uniformly seeded round jet. The results are compared with uncorrected measurements and with results using the McLaughlin–Tiederman correction. The uncorrected results show biasing errors of up to 25%, and the McLaughlin–Tiederman correction works only in the center portion of the jet where the instantaneous flow direction is nearly constant. The McLaughlin–Tiederman correction is restricted conceptually to this flow situation and to uniformly seeded flows. In contrast, the new correction method is not restricted to any particular flow situation. It supplements the new burst-gating counter system described in a parallel paper to form an especially accurate and versatile LDV-signal processor.
Variable angle photoelectron spectrometer
Authors: Mason Douglas C. , Mintz Donald M. , Kuppermann Aron
Published: March 2003

The design, construction, and performance of a spectrometer for measuring the angular and energy distributions of electrons photoejected by rare gas resonance light is described. Results using 584.4-Å photons from a helium lamp are reported. Flexibility of instrumental design allows for the use of other light sources. A 180° hemispherical electrostatic electron energy analyzer is rotatable about the center of an enclosed sample chamber. The instrument is highly automated, with an on-line computer used to control the detector angle and the data acquisition and reduction. This automation is required by the long and continuous data acquisition.
Free-standing microdisk targets for single beam laser experiments
Authors: Varon Joshua
Published: March 2003

This note describes a simple, inexpensive, but very effective method of producing free-standing microdisk targets for single beam laser experiments. Aluminum targets 100 μm in diameter with thicknesses of 1–10 μm have been produced in batches of 2500, having a maximum variation in thickness of less than 10%.
LiNbO3 electro-optic light modulator performing 100% intensity modulation at 550 MHz
Authors: Risch Ch. , Weber H.
Published: March 2003

An electro-optic light modulator using a LiNbO3 crystal of large cross section (1.5 × 1.5 mm2) is described. The LiNbO3 crystal is placed in a 3λM/4 coaxial cavity and may be biased by a dc voltage. 100% intensity modulation at a frequency νM=550 MHz is achieved by maintaining the good optical quality of the modulator. The simple arrangement permits the modulation of light of large spectral width without requiring temperature control.
Microwave ion source
Authors: Sakudo Noriyuki , Tokiguchi Katsumi , Koike Hidemi , Kanomata Ichiro
Published: March 2003

A coaxial microwave ion source which provides high-current ion beams is presented. The microwave discharge takes place in a magnetic mirror field. The intensity of this field is higher than that of the electron cyclotron resonance at 2.45 GHz over the entire discharge region. The antenna of the discharge chamber is water cooled to protect the ceramic which is used as the vacuum seal as well as the conduit for microwaves into the discharge chamber. The ion beam is extracted through a three-stage multiaperture lens with 124 holes 3 mm in diameter. An electron suppressed Faraday cup is used to collect 200-mA argon and 400-mA hydrogen ion beams.
Quadrature interferometer for plasma density measurements
Authors: Buchenauer C. J. , Jacobson A. R.
Published: March 2003

An interferometer has been developed with which it is possible to make accurate plasma density measurements in the presence of density gradients. A modified Mach–Zehnder interferometer employing a linearly polarized scene beam and a circularly polarized reference beam generates signals proportional to the sine and cosine of the phase shift introduced by the plasma. The differential sensitivity of the phase shift measurements is independent of the instantaneous phase angle, and the phase angle may be unambiguously followed through multifringe excursions of the interferometer. The phase shift measurement is also independent of fringe contrast fluctuations caused by the refractive bending of the scene beam by the plasma.
Direct reading dc electro-optic voltmeter with high input resistance
Authors: Geisen K. , Käppler W. , Kühn H.
Published: March 2003

A voltmeter based on the linear electro-optic effect in LiNbO3 has been constructed. Using a compensation technique with two crystals, electric decoupling of the input circuit and the electronic monitoring circuit is achieved. The detected photocurrent is fed back to the second crystal by a solid state high-voltage amplifier. This compensating voltage is monitored on a digital panel meter. Direct- current voltages up to ±1200 V have been measured with an absolute accuracy of ±0.5% ±1 digit over the whole range. The input resistance and input capacitance are Ri=2×1015 Ω and Ci=5 pF, respectively.
Electron beam production by a Tesla transformer accelerator
Authors: Boscolo I. , Leo M. , Luches A. , Provenzano L.
Published: March 2003

We describe the characteristics of an intense electron beam produced by a field emisson diode fed by a Tesla transformer high-voltage (HV) pulser. Beam parameters (current intensity, pulse width, electron energy, etc.) are compared to those calculated, assuming a certain working mode of the HV pulser and solving numerically the resulting differential equation system. The theoretical results agree well with the experimental ones.
Computer assisted correlation spectrometer for the remote sensing of air pollution
Authors: Onderdelinden D. , Strackee L.
Published: March 2003

A correlation spectrometer for the remote sensing of SO2 and NO2 gas burdens in the atmosphere has been developed. The instrument, utilizing natural skylight as its light source, is interfaced to a minicomputer operating in a real time system that controls the scanning monochromator and the data acquisition on disk memory. The main advantage of this approach is that baseline shifts due to spectral variation of the skylight can be eliminated computationally.
Recording coulometer for controlled-atmosphere reactions of metals in molten salts
Authors: Henrie T. A. , MacDonald D. J. , Raddatz A. E.
Published: March 2003

An apparatus was designed and constructed to continuously record mass transfer to or from a metal electrode immersed in a molten-salt electrolyte while a constant current is passed through it, thereby providing a direct measure of the electron-to-atom transfer ratio. Special features include provisions for use of vacuum or inert gas atmospheres and for successive removals and replacements of electrode specimens without disturbing the molten-salt electrolyte. The technique proved successful on electrolyses in the NaCl–TiCl2–TiCl3 molten-salt system.
Optics of single-stage accelerated ion beams extracted from a plasma
Authors: Whealton J. H. , Jaeger E. F. , Whitson J. C.
Published: March 2003

A new iteration scheme for numerical solution of the Poisson–Vlasov system of equations is used to investigate parametric dependence of optics in single-stage ion sources with fixed or similar geometry. Ion optics is found always to be aberration dominated for any reasonable low emittance. Ion temperatures strongly affect the transparency and the optics. The electron temperature has little effect, meaning that out of six physical parameters governing the ion optics only two combinations are important—an ion temperature parameter and the perveance.
Microradiographic characterization of laser fusion pellets
Authors: Henderson T. M. , Cielaszyk D. E. , Simms R. J.
Published: March 2003

A method has been developed to characterize spherical shells geometrically using contact microradiography. The method has been used extensively to study glass shells (of diameters 30–300 μm) used in laser-induced thermonuclear fusion experiments.
Accelerator system for 1-MV STEM
Authors: Marsh G. E.
Published: March 2003

The accelerator, magnetic shielding–equipotential grading system, and voltage divider chain of the University of Chicago 1-MV STEM are described. A dynamical analysis of the system is presented in addition to a discussion of the problem of ’’electron loading’’ encountered while conditioning the accelerator tube.
Response functions of ring-to-axis, axis-to-axis, and n=1.5 cylindrical mirror analyzers with finite source and slit and central angle 30°–65°
Authors: Draper James E. , Lee Cheng-yi
Published: March 2003

Detailed shapes of theoretical response functions are presented for 36 geometries of electrostatic cylindrical mirror analyzers of electron energies. They include ring-to-axis, axis-to-axis, and an intermediate case, and they include seven angles from 30° to 65° for the central ray. The source radius, cylindrical slit width, and collector radius are all of finite extent, unlike the usual approximations, and their sizes are optimized by criteria discussed. Presented are graphs of the optimized slit width, source radius, and collector radius, as well as transmission, normalized counting rate, and the shapes of the response functions. In the calculation of response functions no assumptions are made about the independence of the various contributions to the resolution. The result for n=2, ϑ=60° compares well with an analyzer constructed at Princeton University.
Physical properties of an electron beam—sliding spark device
Authors: McCorkle R. A. , Vollmer H. J.
Published: March 2003

A novel device employing the interaction of a tightly pinched electron beam with a dense plasma formed by a sliding spark capillary discharge has been investigated. Experimental results show that such arrangements are potentially useful for lasing in the short wavelength (below 200 Å) region.
NaF:OH and KCl:OH magnetic field-independent capacitance thermometers
Authors: Hartmann J. B. , McNelly T. F.
Published: March 2003

Capacitance thermometers, fabricated from KCl:OH and NaF:OH crystals, have been studied between 0.065 and 2.5 K. Their sensitivity, d lnC/dT, is one to two orders of magnitude greater than that of commercially available capacitance thermometers over most of this temperature range. NaF:OH was tested for magnetic field independence at 20 and 40 kG; KCl:OH has previously been tested in fields up to 50 kG. Magnetoresistance data, obtained using these thermometers, are presented for Speer 200-Ω, 0.5-W carbon resistors in fields of 20 and 40 kG from 0.07 to 0.4 K.
Mass-dependent channel electron multiplier operation
Authors: Fields S. A. , Burch J. L. , Oran W. A.
Published: March 2003

This paper contains the results of measurements to determine the absolute counting efficiencies and pulse height distributions of a continuous channel electron multiplier (Spiraltron) used in the detection of hydrogen, argon, and xenon ions. The technique involves the post-acceleration of 8-eV ion beams to energies between 100 and 4000 eV. The absolute counting efficiency versus effective ion energy for the ions H2+, A+, and Xe+ is given. The Spiraltron was operated in a marginally gain saturated mode to investigate the charge pulse distribution for the three ions H2+, A+, and Xe+ at ion energies of 3 keV. The pulse height distribution for the light ion H2+ peaked near an equivalent gain of 2×107, while the distributions for the heavier ions displayed no significant peaks. This study suggests that discrimination between light and heavy ions may be accomplished in the energy range E<2 keV by utilizing continuous channel electron multipliers.
Deflection of an ion beam in the two-dimensional electrostatic quadrupole field
Authors: Zeman H. D.
Published: March 2003

The deflecting properties of a two-dimensional quadrupole field have been calculated to second order in input position, angle, and energy. The use of this field as an energy analyzer and as an achromatic deflector are described. The calculated dispersion, which is 84.5% that of of a 127° analyzer of equal angular aberration, has been confirmed by measurement on a deflector designed and built for merging an ion beam with a laser beam. This deflector can bend a 3-kV ion beam of 2-mm diameter, ±2-mrad angular spread, and 1-eV FWHM energy spread by 90° without causing a detectable increase in the diameter or angular spread of the beam.
Simple calorimetric system for the temperature range 3–300 K with on-line computer
Authors: Moses D. , Ben-Aroya O. , Lupu N.
Published: March 2003

In this report we describe a computerized adiabatic calorimetric system operating in the temperature range 3–300 K, with an accuracy better than 0.3%, limited mainly by the accuracy of thermometer calibration. The calorimetric system measures and calculates the specific heat as a function of the temperature, which in turn is obtained from computer-stored thermometer calibration curves. The system is able to work in a discrete or a continuous heating mode and provides the computed results during the measurements. The cryostat, the adiabatic shield control, the electronic system, and the software logic are described.
Simple multisample stage for the scanning electron microscope
Authors: Bowers F. M. , Ellis S. G.
Published: March 2003

The stage is made by drilling a large stub so that it will receive three small stubs. The rotary control allows all three stubs to be viewed.
Noninductive current probe
Authors: Bak C. K.
Published: March 2003

The current probe described is a low-cost, shunt resistor for monitoring current pulses in e.g., pulsed lasers. Rise time is <5 nsec, inductance introduced in the circiut <7 nH, and current handling capability ∼100 A2 sec.
Piston gauge weight handler
Authors: Davis Harry
Published: March 2003

An electromechanical hydraulic lift has been developed and subsequently used to load and unload weight stacks from precision piston gauges without affecting the reliability or the operation of these gauges.
Method for heat injection into a liquid
Authors: Shlien D. J.
Published: March 2003

A novel technique of heat injection into a liquid is presented. Advantages of the technique (based on direct ohmic heating) include the ease with which the apparatus can be set up and its simplicity of operation. Very small heat sources can be fabricated to closely approximate point sources.
Low-consumption atomic beam source
Authors: Witteveen G. J.
Published: March 2003

A sodium atom beam source is described in which those atoms which intercept the collimator surface are returned to the oven chamber, thus minimizing the total sodium consumption for a given collimated beam intensity.
Bridge for differential tunneling spectroscopy
Authors: Colley S. , Hansma P.
Published: March 2003

Conventional, single junction inelastic electron tunneling spectra contain undesirable background structure due to the metal electrodes and the oxide layer. This structure can be minimized with a bridge that measures the difference between the tunneling spectra of doped and undoped junctions.
Versatile multicontact thin-film superconducting switch
Authors: Finnegan T. F. , Holdeman L. B.
Published: March 2003

A versatile mechanical superconducting switch which is suitable for use in various cryoelectronics applications has been developed. The switch design utilizes thin films for compactness and proximity layers of gold to prevent contact oxidation. A prototype four-pole, four-position switch is described in detail.
Simple closure for high pressures and low temperatures
Authors: Goedegebuure W. , Schouten J. A. , Trappeniers N. J.
Published: March 2003

A new seal is described which can be used at pressures up to 15 kilobar.
Simple goniometer for precise grinding and electropolishing of single crystal surfaces
Authors: Wendelken J. F. , Withrow S. P. , Foster C. A.
Published: March 2003

A simple goniometer, which can be used to rigidly support a crystal in a precise orientation through all phases of surface preparation, including mechanical, chemical, and electrochemical polishing, is described.
Low-noise circuitry for low-temperature NMR and SQUIDs
Authors: Conradi Mark S. , Edwards Carl M.
Published: March 2003

A method of coupling the low-temperature induction coil of an NMR or SQUID system to a preamplifier is proposed. This method greatly reduces the Johnson noise generated by line losses. A suitable 9-K noise-temperature GaAs FET, liquid nitrogen cooled preamplifier is described. The coupling scheme and preamplifier will yield a spectrometer with a noise temperature near 15 K.
Improved emission control for the MRC electron beam zone refiner
Authors: Kamm G. N.
Published: March 2003

Greatly improved emission current regulation can be obtained for the beam filament in MRC electron beam zone refiners by replacing the existing magnetic amplifier regulator by a programmable electronically regulated dc power supply and an operational amplifier control circuit. This yields much longer filament lifetimes with less contamination of the specimen and permits delicate crystal growing operations not otherwise possible.
PTFE seal for superfluid He
Authors: Windgassen N. R.
Published: March 2003

A design is given for a demountable, space saving, nonsuperconducting PTFE (Teflon) bakeable seal which is vacuum tight for superfluid helium.
Laser-driven 3 kA x-ray source
Authors: Roth Shmuel , Freund Isaac
Published: March 2003

An x-ray source driven by a 10-pps Nd–YAG laser is described which, because of its high peak power and automatic synchronization to the laser, is especially suited for the study of x-ray optical interactions. The device is of very simple construction, is based upon a 1-m-long 3-Ω coaxial transmission line charged to 40 kV, and delivers 20-ns wide pulses at peak currents of ∼3 kA. A simple analysis which is in good agreement with experiment predicts that a 1-Ω line charged to 60 kV should yield peak currents of ∼15 kA.
Micro-Fresnel zone plates for coded imaging applications
Authors: Ceglio N. M. , Smith Henry I.
Published: March 2003

Design considerations and fabrication procedures for Fresnel zone plates appropriate for high-resolution coded imaging of x-ray and particle emission from laser produced plasmas are presented. Fabrication results for free standing zone plate structures of high Z material (gold), large zone number (100⩽n⩽240), microscopic minimum linewidth (2.6⩽Δr⩽10.2 μm), and appreciable material thickness (1⩽t⩽7 μm) are reported.
Full-photon-counting Rayleigh spectrometer: a correlation and/or fast Fourier transform instrument
Authors: Han Charles C.
Published: March 2003

A fast, flexible, and relatively inexpensive minicomputer based Rayleigh spectrometer has been constructed. This spectrometer can utilize photon pulses in a most efficient way by performing autocorrelation and/or FFT with any desired number of channels. Its capability has been demonstrated by measuring large latex particles, small sodium dodecyl sulfate micelles, and a polydisperse latex-γ-globulin system. Detailed timing diagrams and circuit schematics are also included.
Pressure vessel for tensile testing in high-pressure gases at elevated temperatures
Authors: Yokogawa Kiyoshi , Fukuyama Seiji , Mitsui Murao , Kudo Kiyokatsu
Published: March 2003

A pressure vessel for tensile testing has been developed to measure tensile stress in high-pressure up to 50.5 MPa at elevated temperatures up to 773 K. The vessel is designed to facilitate the measurement of the actual tensile load on the specimen by an external load cell without the influence of axial stress due to high pressure in the vessel and the effect of friction at sliding seals where the load rod enters the vessel. Application of the vessel to tensile testing of a steel in hydrogen atmosphere is briefly described.
Low-noise amplification of voltage and current fluctuations arising in epithelia
Authors: Van Driessche W. , Lindemann B.
Published: March 2003

Two low-noise differential input amplifiers designed for voltage and current fluctuation measurements in epithelia are described. The first one uses a matched pair of low-noise transistors and is particularly suited for low-frequency current and voltage noise measurements in frog skin and other preparations with impedances below 1 kΩ. The second one is designed around a matched pair of JFETs and can also be used for higher source impedance. Performance is demonstrated with Na+ current power density spectra obtained from frog skin with the transistor-input stage.