bluuebunny/crossref_metadata_2025 huggingface dataset:
Hollow cathode startup using a microplasma discharge
Authors: Aston Graeme
Published: March 2003

The use of a microplasma discharge to initiate a hollow cathode discharge is described. Operating characteristics of a hollow cathode designed and built around this starting concept are presented. Possible applications for this hollow cathode are discussed.
Vacuum ultraviolet H2 laser excited by a traveling-wave discharge
Authors: Kirklan J. , Doggett F W. O. , Kim J. J.
Published: March 2003

A vacuum ultraviolet molecular hydrogen laser was pumped by a traveling-wave discharge in a novel slotted Blumlein transmission line. Reported herein is the design of the laser system and the results of a measurement of the speed of the traveling-wave discharge in a VUV H2 laser, (25.2±1.8 cm/ns). Also described is the experimental technique used to measure the speed of the breakdown propagation.
Apparatus to study the electron spin resonance of fluids under high pressure flowing at high temperature
Authors: Livingston Ralph , Zeldes Henry
Published: March 2003

An electron spin resonance (ESR) system is described in which a fluid sample is pressurized and flowed through a fused silica capillary that traverses the microwave cavity of an ESR spectrometer. The capillary is heated to a high temperature, and well-resolved spectra of short-lived free radicals may be seen at steady-state concentration during pyrolysis. The system operates to 20.7 MPa and 700 °C. High-pressure hydrogen may be injected prior to pyrolysis. A spectrum of benzyl during pyrolysis of toluene at 20.7 MPa and 680 °C is shown.
Comparison test of the response to pitch angles of some digital hot wire anemometry techniques
Authors: Andreopoulos J.
Published: March 2003

The same real time hot-wire data have been processed digitally by the cosine law method and that of Friehe and Schwarz for various pitch angles of the probe holder. It was found that mean velocities and turbulence intensities can be measured quite accurately even at very high pitch angles by the cosine law, while shear stresses can be measured with much better accuracy by the Friehe and Schwarz method.
Refractive index change and curvature in shock waves by angled beam refraction
Authors: Kiefer J. H. , Manson A. C.
Published: March 2003

Observations of front geometry and refractive index jump across shock waves in rare gases have been made with a new and particularly simple technique. The technique involves determination of the angular deflection of a narrow laser beam intersecting the shock front at a shallow angle. Measured refractive index jumps in rare gases are in excellent agreement with those calculated using Snell’s law and ideal shock theory. The apparent shock curvature is in close accord with deBoer’s theory for loading pressures below 20 Torr, but above this presure there is evidence of an indentation near tube center.
Simple control circuit for temperature regulation and other bridge applications
Authors: Cutkosky R. D. , Davis R. S.
Published: March 2003

A circuit is presented that makes use of low frequency square waves for exciting resistance bridges, detecting their departure from balance, and providing an output voltage for measurement or control purposes. Applications in several areas of precision metrology have been found.
Digital technique for the study of narrow structure in electron-atom and electron-molecule scattering
Authors: Paske W. C. , Shadfar S. , Lorentz S. R. , Steph N. C. , Golden D. E.
Published: March 2003

A digital technique has been developed which allows the study of narrow structure in total electron-atom and electron-molecule scattering cross sections without requiring a highly monoenergetic electron beam, modulation of the electron gun, or phase sensitive detection. The electron current transmitted through a gas cell is digitized as the electron energy is stepped by ΔE through the energy range of interest. A transmitted electron difference signal is then obtained using a computer. As examples of this technique, the difference spectra are presented for He near 19.35 eV and for N2 for the energy range from 10.3 to 15.0 eV. In the present case an instrumental resolution of 30 meV FWHM has been obtained.
Simple photoacoustic cell operating at N2 liquid temperature
Authors: Nunes O. A. Cleves , Monteiro A. M. M. , Neto K. Skeff
Published: March 2003

A simple low-temperature photoacoustic cell operating at the liquid N2 temperature is described. An application is made for monitoring the thermal agitation of a spin system close to its order–disorder critical temperature.
High repetition rate pulsed nozzle beam source
Authors: Cross Jon B. , Valentini James J.
Published: March 2003

A high repetition rate piezoelectric pulsed molecular beam source is described. Reptition rates as high as 750 Hz have been obtained with gas pulse widths from 100 μs to 10 ms. The measured expansion characteristics are very nearly those of an ideal isentropic expansion. The valve is highly reliable: We have obtained 107 pulses without failure.
Computerized refractive index measurements for bulk materials at UV, visible, and IR wavelengths
Authors: Wood D. L. , Fleming J. W.
Published: March 2003

A computer-controlled apparatus was built to measure refractive index and its temperture coefficient to fifth decimal place accuracy at UV, visible, and IR wavelengths. Deviation of monochromatic radiation through a prism having a reflecting rear surface is measured by the autocollimation method as in a Littrow prism spectrometer. Entrance and exit rays at the prism are superimposed, so that a fixed entrance/exit port permits convenient temperature-controlled enclosures for measurement of dn/dT. Angle measurments involve only rotation of the prism, making use of a 20-bit digital angle sensor suitable for computer readout. A geared stepping-motor drive permits computer control of data acquisition and processing. Useful wavelength coverage has so far included the range from 0.25 to 8 μm, but is limited only by source intensity, detector senstivity, and sample prism transparency. Index results for four germano–silicate glasses at 22 wavelengths between 0.36 and 1.69μm are reported and values of dn/dT for pure SiO2 to 373 K (100̊ C) are given. Sellmeier coefficients from fitting a three-term formula are listed, and determination of material dispersion values from the Sellmeier coefficients is discussed in terms of their use in optical fiber modeling calculations.
Infrared laser microwave double-resonance spectrometer with a high-precision multipass stark cell
Authors: Tanaka Takehiko , Inayoshi Akira , Kijima Kazuhiro , Harada Kensuke , Tanaka Keiichi
Published: March 2003

A spectrometer for infrared microwave double resonance with an intense Stark field is described that is useful for accurate determination of dipole moments and other electric properties of molecules. High precision and sensitivity are attained by the use of gold-coated glass optical-flat Stark plates, a white-type multiple reflection optical path, and microwave frequency stabilization. The spectrometer was tested by observing double resonances in H2CO with a CO laser as an infrared light source, and was shown to be adequate for measurement of dipole moments to better than ±10−4D.
Bolometer for measurements on high-temperature plasmas
Authors: Schivell J. , Renda G. , Lowrance J. , Hsuan H.
Published: March 2003

A bolometer has been developed based on a thin, die-cut platinum grid. It can survive high temperatures and the neutron and gamma radiation expected in the Toroidal Fusion Test Reactor (TFTR). The platinum resistance is measured with a square-wave carrier system to minimize sensitivity to ambient electromagnetic interference. Electrical power fed back to the sensor holds its temperature constant and provides an output directly proportional to absorbed radiation power. With a bandwidth of 50 Hz the noise is equivalent to 100 μW/cm2. Methods are described for dealing with the background effects expected to contribute to bolometer heating.
Mosfet high-power pulsed rf emitter—a design for nuclear-magnetic-resonance imaging
Authors: Darrasse Luc
Published: March 2003

We present a 350-Wrms pulsed emitter based on a single Mosfet device working with square-wave driven Class C. By tuning one single resonant circuit in the drain load, its operating frequency may be placed anywhere up to 15 MHz. With currently available Mosfet devices, the output power may be upgraded to several kW. This emitter also features sharp rf pulse edges, extremely high noise immunity, and provision for pulse envelope modulation. It is well suited for applications such as broadband nuclear magnetic resonance, especially if medical imaging is considered.
Unified approach to photographic methods for obtaining the angles of incidence in low-energy electron diffraction
Authors: Sobrero A. Charles , Weinberg W. Henry
Published: March 2003

An equation is developed to describe the geometrical relationships between the electron gun, the crystal surface, and the phosphorescent display screen in back-reflection, post-acceleration LEED experiments. Photographic methods for determining the polar and azimuthal angles of incidence in LEED experiments can be derived starting from this equation. In particular, two published procedures appear here as special cases. New methods are described for cases where the existing techniques do not apply. It is shown that the alignment of the electron gun and the positioning of the crystal can be checked using a photographic technique. An example illustrates that the angles of incidence can be measured with precisions of ±0.2° by recording data on several photographs taken over a wide range in electron energy.
Temperature-jump apparatus with infrared detection for relaxation studies in thin samples
Authors: Möller Karl O. , De Maeyer Leo C. M.
Published: March 2003

A temperature-jump apparatus with infrared detection is described, which has been developed for investigation of chemical reaction kinetics in electrically nonconducting systems: e.g., lipids, liquid crystals, and organic solutions. The sample (volume 8 μl) is attached on one side of a multireflection germanium-ATR plate (ATR = attenuated total reflection). The two long edges of the plate are p and n doped in an alloying process and connected to electrodes. The plate can be heated in less than 50 μs by several degrees K with a capacitor discharge of 1.8 kV. The sample is heated by heat conduction. Changes in infrared absorption are detected with a liquid nitrogen cooled HgCdTe photoconductive device. The homogeneity of temperature distribution on the plate surface after the T jump has been verified with a thermographic video camera. Performance tests have been carried out with a liquid crystal by observing its melting process.
Direct reading, noise immune resistance comparator for measurement of temperature and pressure
Authors: Gro/nlund Finn
Published: March 2003

Design of a circuit intended for pressure measurement with a manganin cell in the range 0–10 kbar (1 bar = 105 Pa). The output voltage is strictly proportional to the difference between the cell resistance and a reference resistance, changes smaller than 0.1 mΩ in 100 Ω are detectable, and noise is negligible. A similar design may be used in resistance thermometry.
Considerations on burst disk use in closed-cycle helium liquefier systems
Authors: Spencer Gregory F. , Fombarlet Christian , Ihas Gary G.
Published: March 2003

Considerations for the use of burst disks in the gas storage bank of a closed-cycle helium liquefier-recovery system are presented. Attention is focused on the unpredictable characteristics of these devices as well as on the aging processes inherent in them.
Calcium fluoride window mounting
Authors: Berger D. Douglas
Published: March 2003

A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.
High-temperature insulation for the copper vapor laser
Authors: Kim Jin J. , Convey Joel F.
Published: March 2003

A simple and inexpensive technique is presented for efficient thermal insulation for the copper vapor laser. This technique will allow for construction of a nanosecond rise-time transverse discharge system for the copper vapor laser.
Modification of a Kel-F-glass vacuum valve to give a gold-to-glass vacuum seal
Authors: Jones Wesley M.
Published: March 2003

Modifications of a commercial Kel-F-glass vacuum valve are described which give a gold-to-glass vacuum seal for use with corrosive gases. A valve that had been used with sulfur trioxide was found to be leak free with a helium leak detector.
Flow-through photoacoustic cell
Authors: Helander Per
Published: March 2003

An open photoacoustic cell has been modified to allow a fluid sample to continuously flow through the cell. The important features of the cell are discussed and demonstrated by experiments. Possible applications of the cell are outlined.
Miniature connectors for low-temperature cryostats
Authors: Schmiedeshoff G. M. , Gully W. J.
Published: March 2003

A compact terminal and heat sinking arrangement for shielded cable at dilution refrigerator temperatures is described.
TEA laser gas mixture optimization
Authors: Lipchak W. Michael , Luck Clarence F.
Published: March 2003

The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO2 TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.
Horizontally rotating light-beam chopper
Authors: Kendall-Tobias W. W.
Published: March 2003

A horizontal rotor can be used as an alternative to the common vertical chopper for light-beam modulation. The horizontal rotor is more compact than the vertical type and the modulation duty cycle is variable. This kind of chopper is well suited to the alternate modulation of two light beams. A well-designed chopper should be able to function as either a vertical or horizontal light modulator.
Plasma target output from a magnetically augmented, gas-injected, washer-stack plasma gun
Authors: Osher J. E.
Published: March 2003

This article describes a new washer-stack gun design developed for the application of plasma target production for the startup of neutral-beam trapping in a fusion research magnetic confinement system. The gun is a Mo anode type that is D2 injected and has an auxiliary pulsed magnet for control of plasma-flux mapping. One of the principal features of 2–10-ms duration pulses for gun operation in a suitable magnetic field is the formation of an arc column along magnetic field lines from the gun’s central cathode electrode to the vacuum chamber walls (at common anode potential). The primary power output from a 5.0-cm-i.d. gun is typically carried along this arc column by a stream of approximately 2000 A of 50–250-eV electrons. This primary stream of relatively low-density energetic electrons efficiently ionizes the injected gas, forming a quasi-dc source of denser secondary plasma of ∼1013/cm3 at a few eV, which is able to flow or diffuse away along a somewhat larger column of magnetic field lines. In plasma-target production tests on a test stand, a gun operated at a D2 gas flow of 22 Torr ls−1 yielded 250 A of equivalent plasma flow.
Graphical analysis method for a retarding potential analyzer and its application to the real-time measurements of ion temperature in space plasmas
Authors: Minami Shigeyuki , Tsutsumi Shiro , Takeya Yoshio
Published: March 2003

In order to obtain the ion temperature from a voltage-to-current characteristic of a retarding potential analyzer (RPA) in a drifted density (106 1/cc), low-temperature (1 eV) plasma such as an ionospheric plasma, optimum fitting procedures using the digital computer have been used. But these methods must take a lot of time to search the parameters. A graphical method using the sampling of a RPA curve has been developed to obtain the ion temperature quickly. Many diagrams were drawn by calculation to determine the ion temperature. This method is suitable not only for the processing of a large quantity of data but also for the in-flight data analysis aboard a sounding rocket. By the use of feedback control circuits, ion temperature data could be obtained at a ratio of several tens per second in the ionosphere, where the mass of the ion M varies slowly. The accuracy of this method and the effect of variations of M, angle of attack Θa, and drift velocity v0 is discussed. Also the efficacy of this method is confirmed. This method was examined in the ionosphere aboard a rocket whose velocity was about 2 km/s. The ion temperature data obtained are compared with those obtained by the usual optimum fitting procedure.
Application of light polarization technique to the generalized line-reversal method for gaseous temperature measurements
Authors: Kayukawa N. , Aoki Y. , Ozawa Y.
Published: March 2003

The light polarization technique was applied to the generalized line-reversal method in order to improve the inherently restricted resolution characteristics found in the conventional method using a chopper or a knife wedge, which discriminate the reference lamp light from the gaseous emission either temporally or spatially, respectively. In the proposed method, each of the lights was linearly and perpendicularly polarized and was detected through the same spatiotemporal optical path. The applicability of this method to measure the hot gaseous temperature was confirmed experimentally in a shock tube MHD power generation system.
Fabrication of ultrashort niobium variable-thickness bridges
Authors: Goto T.
Published: March 2003

A simple technique for the fabrication of niobium variable-thickness bridges of length ∼0.1 μm is described. The bridges are found to operate as ideal Josephson junctions over a wide temperature range.
Observations of sonoluminescence using image intensification
Authors: Reynolds George T. , Walton Alan J. , Gruner Sol M.
Published: March 2003

A high-gain image intensifier system has been applied to the study of the light emitted when cavitation occurs in a liquid (sonoluminescence). Observations of sonoluminescence from several different magnetostrictive oscillators show that spatial and temporal distributions can be recorded in a few seconds in cases where recording on conventional film would not be possible. In the present experiments, the spectral transmission properties of the optics precluded recording of the light in ultraviolet. The spatial details of the cavitation process would not be available from photomultiplier records.
Phase-locked heterodyne receiver and its application to lower hybrid wave detection by microwave scattering
Authors: Uesugi Y. , Itoh T. , Takamura S. , Okuda T.
Published: March 2003

The frequency stabilized, low-noise heterodyne receiver is developed for microwave scattering measurements in a plasma. Its application to the observation of a lower hybrid wave (LHW) externally excited in a linear test plasma is demonstrated. The frequency fluctuation of 70 GHz klystrons employed for scattering measurements is stabilized by the phase-locked loop. The frequency resolution of the receiver is about 10 kHz and its noise equivalent power is about 7×10−19 W/Hz, corresponding to the minimum detectable density fluctuation ñe/n̄e=6×10−5 under present experimental conditions. By the scattering of 70 GHz millimeter waves using this heterodyne receiver, LHW externally excited by the helical antenna can be detected. The spatial intensity distribution and the wave number spectrum of the scattered power are obtained. These observations make clear not only the magnitude, but also the direction of the wave number of the excited wave. The observed wave numbers in the several scattering positions over the plasma cross section are almost in the radial direction but not always consistent with the theoretical expectations. Their magnitudes are close to those determined from the auxiliary measurements using an electrostatic probe. The density fluctuation obtained from the absolute value of the scattered power is about ñe/n̄e=5×10−4. The theoretical estimation gives ñe/n̄e=2×10−3.
Movable target assembly for diode sputtering system
Authors: Stone C. A. , Roz̆aj-Brvar A. , Davis R. F.
Published: March 2003

A decrease in the energy of sputtered atoms may be accomplished by either altering the gas pressure or the target-substrate distance. Increased gas pressure is sometimes accompanied by a deterioration in the quality of the deposited film. To offset this negative aspect, a movable cathode assembly with external control and direct measurement of separation distance has been designed and employed for the rf sputtering of SiC.
Television camera for fast-scan data acquisition
Authors: Noel B. W. , Yates G. J.
Published: March 2003

A fast-scan television camera is described that was designed specifically for closed-circuit data-acquisition applications. The camera is capable of field durations as low as 2.8 ms. The line and field rates are quasicontinuously adjustable. The number of lines, the integration duty cycle, and the scan direction are among the other adjustable parameters. Typical resolution at the fastest scan rate is ≳500 TV lines per picture height with a corresponding dynamic range (to light input) of more than 100. The camera uses the unique properties of FPS vidicons and specially designed electronics to achieve its performance level and versatility.
New spectrometer and sample technique for deuterium analysis of enriched water samples
Authors: Dumke J. , Niemann E.-G. , Brandt H.-W. , Heilig K.
Published: March 2003

The intensities of the atomic lines Hα and Dα produced in a high-frequency discharge in water vapor are measured to determine the deuterium content. A special spectrometer uses an interference filter and a Fabry–Perot interferometer for simultaneous recording of both intensities. Electronic calculation gives an observed intensity ratio which can be corrected via a calibration curve, thus yielding the deuterium content in percent. The relative accuracy of the method depends on the enrichment: above 1% deuterium the relaltive limit of error is about ±1%, down to 0.3% deuterium it is better than ±5%. A deuterium concentration of 0.03% can just be distinguished from normal water.
Typing a semiconductor with point contacts
Authors: Dhar S. , Nag B. R.
Published: March 2003

The results of typing measurements of semiconductor samples using a metal-semiconductor point contact technique, under different experimental conditions, are presented. The information obtained from these experiments has been verified for correctness by using standard techniques. A circuit arrangement is described which can be attached to a conventional four-probe resistivity jig in order to extend the applicability of the latter for determination of the type of a sample along with its resistivity measurements.
Low-voltage, high-current electron gun
Authors: Erdman Peter W. , Zipf Edward C.
Published: March 2003

A simple, high-performance, electrostatically focused electron gun, which is useful over an energy range extending from a few electron volts to at least 500 eV, is described. The current is delivered in a beam ∼1 mm in diameter, with <50 mrad angular divergence and typically has a current over 1 mA at 100 eV. The design is small, compact, and rugged. This electron gun has been used successfully in both laboratory and sounding rocket experiments.
Mathematical treatment of heat flow in differential scanning calorimetry and differential thermal analysis instruments
Authors: Mraw Stephen C.
Published: March 2003

A general mathematical treatment is given which relates the techniques of classical differential thermal analysis, power-compensated differential scanning calorimetry, and heat-flux differential scanning calorimetry. An idealized system, representative of almost any type of differential thermal instrument, is presented, which, unlike those of previous treatments, incorporates two separate thermal resistances. This modification allows the heat-flux d.s.c. instrument to be considered in a unified analysis with the other techniques. General aspects of the idealized system are presented, and the equations governing heat flow within the system are developed. For each separate technique, the components of the idealized system are identified with the actual components of the physical instrument, and the specific equations which describe the measuring principles of that technique are derived. It is shown that a similar type of thermal resistance governs sample-temperature lag in both the power-compensated and heat-flux d.s.c. cases, and the method of estimating the value of this resistance from the slope of a fusion peak is discussed.
Robinson-type nuclear quadrupole resonance spectrometer adapted to field-effect transistors
Authors: Lee Jongmin , Choh Sung Ho
Published: March 2003

A nuclear quadrupole resonance spectrometer, the Robinson circuit adapted with field-effect transistors, has operated satisfactorily up to 30 MHz with rf levels ranging from 40 mV to 2.6 V peak to peak across the sample coil. The S/N ratio of 14N in hexamethylenetetramin is 85 at room temperature and 150 at 77 K, with a sample volume of 6 cm3 and a time constant of 10 s. The spectrometer is also capable of measuring the spin-lattice relaxation time by the saturation method.
New technique for measuring wind velocity
Authors: Khandelwal Govind S. , Singh Jag J.
Published: March 2003

A new technique for measuring wind velocities of meteorological interest is described. It is based on inverse square law variation of the counting rates as the radioactive source-to-counter distance is changed by the movement of the source caused by the wind velocity. The technique is usable anywhere, for all noncorrosive media, except in places with no local gravitational force. Measurements reported herein indicate that the proposed technique may be quite suitable for measuring wind speeds in the range of 5–100 m/s, that are either steady, or, whose rates of fluctuation are less than 1 kHz.
Optical technique for determining rarefaction wave velocities at very high pressures
Authors: McQueen R. G. , Hopson J. W. , Fritz J. N.
Published: March 2003

An optical technique to determine rarefaction wave velocities is described. The technique utilizes the property that many transparent materials emit copious radiation when shocked to high pressures. The usual method of producing a rarefaction wave by impacting a target plate with a thinner rapidly moving driver plate is employed. The target plate is made in the form of a step wedge which is covered by the transparent material (or analyzer). When the shock reaches the analyzer it radiates steadily until the rarefaction from the backside of the driver plate overtakes the shock front causing the radiation to decrease. The time between these events is a decreasing linear function of the target thickness and when extrapolated to zero determines the thickness where the rarefaction would have overtaken the shock wave at the surface of the target. Light pipes are used to transmit the radiation to photomultipliers whose response is measured by high-speed oscilloscopes.
Best absorber for CO2 laser light
Authors: Hidaka T. , Kumata K.
Published: March 2003

A new CO2 laser-light absorber made with 50 mol% GeO2–25 mol% ZnO–25 mol% K2O (alkali–zinc–germanate) glass has been developed with a specular reflectance of less than 0.1% at 10.6 μm. An example of the application of the absorber to a laser powermeter is described.
New method for focusing x rays and gamma rays
Authors: Smither R. K.
Published: March 2003

A new method for focusing x rays and gamma rays is described that can focus monochromatic radiation from a point source or parallel beam down to a line image. If two focusing elements are used or if a single element bent in two directions is used, the radiation can be focused to a point image. Conversely, radiation from a point source can be converted into a parallel beam. The method makes use of bent diffraction crystals in which the intercrystalline-plane spacing is varied as a function of position in the crystal. The Bragg angle for diffraction of monochromatic radiation will now vary as a function of position in the crystal, and this new degree of freedom can be used to obtain focusing of the diffracted beam. A number of ways to achieve this variation in crystal-plane spacing is discussed, including the use of thermal gradients and the variation of the elemental composition of the crystal. The applications of this new focusing system to a gamma-ray telescope and to the production of a real image of a strong x-ray source are considered.
Fast response Faraday cup for low-energy, nanosecond-pulse ion beams
Authors: Iida Toshiyuki , Taniguchi Ryoichi , Fujimoto Toshiaki , Sumita Kenji
Published: March 2003

A fast response Faraday cup has been developed for measuring low-energy, nanosecond-pulse ion beams. It is made of a coaxial Faraday cup before which a thin gold foil has been set, and it measures the waveform of low-energy, nanosecond-pulse ion beams by using the secondary electrons emitted in the forward direction from the foil.
Purity of He(23S) beams produced by coaxial electron impact sources
Authors: Onellion M. , Riddle T. W. , Dunning F. B. , Walters G. K.
Published: March 2003

Under certain operating conditions a helium metastable atom source based on coaxial electron impact excitation is observed to produce a beam that comprises principally fast neutral, rather than metastable, atoms. Implications of this are discussed.
Interfacing a pH meter to allow automatic pH adjustment
Authors: Hertl W. , Ramsey W. S. , Carter C. N. , Sokoloski E. J.
Published: March 2003

An add-on device for the automatic adjustment of solution pH is described which can be used with any pH meter with an alarm circuit. The desired pH is keyed into the pH meter, and the add-on device controls the addition of acid or base until the desired pH is attained. Unbuffered solutions can be automatically adjusted to within 0.1 pH unit and buffered solutions to within 0.005 pH unit.
Efficiencies of gas neutralizers for multi-MeV beams of light negative ions
Authors: Grisham L. R. , Post D. E. , Johnson B. M. , Jones K. W. , Barrette J. , Kruse T. H. , Tserruya I. , Da-Hai Wang
Published: March 2003

We report measurements of the neutral and charged particle fractions produced by running beams of Li−, C−, O−, and Si− at energies up to 7 MeV through gas cells of N2, Ar, or CO2. We discuss the implications of these measurements for the design of neutralizers to produce high-energy light atom beams for heating or current drive in tokamaks.
New temperature measurement technique for thermal plasmas
Authors: Mehmetoḡlu M. T. , Kitzinger F. , Gauvin W. H.
Published: March 2003

A novel electro-optical technique for the measurement of radial and axial temperature profiles in thermal plasmas has been developed. It is based on the determination of the variations in the outputs of a two-wavelength pyrometer that views a small section of the plasma, as the latter is swept rapidly by a blocking element. This diagnostic technique was used to determine the temperature profiles in the plasma column of an argon transferred arc. Temperatures up to 18 000 K were recorded on the axis of the plasma column near the cathode tip.
Automatic apparatus for catalyst characterization by temperature-programmed reduction/desorption/oxidation
Authors: Boer H. , Boersma W. J. , Wagstaff N.
Published: March 2003

An apparatus is described for the automatic quantitative registration of reduction, desorption/adsorption, and oxidation phenomena which occur when a catalyst sample is heated or cooled under temperature programming in a flowing gas that contains either hydrogen or oxygen as the reactive component. The design considerations and the automation scheme are fully discussed. A typical example of the characterization of a catalytic reforming catalyst by means of its temperature-programmed reduction, (hydrogen) desorption, and oxidation profiles is shown. Quantitative results are repeatable to within 1% relative.
Influence of convection, conduction, and radiation on the frequency response of heat fluxmeters
Authors: Malcorps H.
Published: March 2003

A simple model for a heat fluxmeter, exchanging heat by radiation, convection, and conduction with the surrounding air is introduced. The final analytical solution is interpreted by means of electronic analog circuits and an explanation of the properties of the radiometer of Gier and Dunkle (AIEE Trans. 70, 107–114, 1953) is given.
Distribution of radioactivity in a spark-source mass spectrometer
Authors: Chastagner P.
Published: March 2003

An AE1 MS7 spark-source mass spectrometer was decommissioned after 18 years of analytical service. More than 2000 of the 6200 samples analyzed were highly radioactive materials including Cf, Cm, Am, and Pu. A total of about 0.5 Ci(∼1×1012 dpm) of α radioactivity was put into the instrument. Many of the samples were contaminated with small amounts of β and γ emitters. As predicted, most of the radioactivity remained in the source housing and was removed with the source plates and shields. About 1×108 dpm migrated to the ion-source pumping line. Contamination in the magnetic analyzer was about 100 dpm/100 cm2. No activity was detected in the photoplate magazine.
Ultraviolet laser, short pulse-width measurement by multiphoton ionization autocorrelation
Authors: Rayner D. M. , Hackett P. A. , Willis C.
Published: March 2003

An autocorrelation technique for the measurement of ultrashort laser pulse widths in the ultraviolet is demonstrated. Multiphoton ionization is used as the nonlinear process.
Small solenoid with a superconducting shield for nuclear-magnetic-resonance near 1 mK
Authors: Muething K. A. , Edwards D. O. , Feder J. D. , Gully W. J. , Scholz H. N.
Published: March 2003

A small superconducting solenoid to provide the steady homogeneous field for NMR at ultralow temperatures is described. The solenoid is shielded by a superconducting tube and there is a simple method of computing the field distribution. Three different shield materials, Pb, Nb–Ti, and pure Nb, were investigated. The final version of the solenoid and shield gives a field of ∼0.5  T with a homogeneity of ∼5×10−4 over 1 cm with, heating of less than 0.1 μ W.
Simple jig for orienting and polishing a single crystal
Authors: Chang Y. K.
Published: March 2003

A simple device was constructed for preparing single-crystal surfaces. The jig can be used to accurately orient and polish crystals along any desired crystallographic plane without undesired transfer of the sample from one device to another. The mounted specimen may be removed for examination and easily reloaded back into the jig without loss of orientational reference. Excellent results were obtained with many soft and hard crystals.
Cellstat—A continuous culture system of a bacteriophage for the study of the mutation rate and the selection process at the DNA level
Authors: Husimi Yuzuru , Nishigaki Koichi , Kinoshita Yasunori , Tanaka Toyosuke
Published: March 2003

A bacteriophage is continuously cultured in the flow of the host bacterial cell under the control of a minicomputer. In the culture, the population of the noninfected cell is kept constant by the endogeneous regulation mechanism, so it is called the ’’cellstat’’ culture. Due to the high dilution rate of the host cell, the mutant cell cannot be selected in the cellstat. Therefore, the cellstat is suitable for the study of the mutation rate and the selection process of a bacteriophage under well-defined environmental conditions (including physiological condition of the host cell) without being interfered by host-cell mutations. Applications to coliphage fd, a secretion type phage, are shown as a measurement example. A chimera between fd and a plasmid pBR322 is cultured more than 100 h. The process of population changeovers by deletion mutants indicates that the deletion hot spots exist in this cloning vector and that this apparatus can be used also for testing instability of a recombinant DNA.
Coupling device for quick high-pressure connections to 100 MPa
Authors: Yayanos A. Aristides , Boxtel R. Van
Published: March 2003

The joining of a pressure vessel to a pumping system was achieved quickly with a threadless coupling device consisting of a coupler and an adapter. The easily made adapters were attached to standard high-pressure valves having a 6.35-mm female fitting. The coupler was attached to a high-pressure pump by flexible stainless-steel tubing for use to 100 MPa (1000 bars).
Automatic control for a Helitran exhaust gas heater
Authors: Yanowski E.
Published: March 2003

We describe a simple circuit for use with Helitran cryostat systems which provides automatic control of the instruments’ exhaust gas heater. Both digital and analog heater control circuits are discussed. This circuit considerably simplifies operation of the instrument as well as provides protection against damage.
Low-energy ion beam system for materials studies
Authors: Nelson G. C. , Borders J. A. , Oborny M. C.
Published: March 2003

An ion accelerator system has been developed for the measurement of low-energy, hydrogen isotope sputter yields. This system provides well-characterized, mass-analyzed beams of hydrogen isotopes at low ion energies and high current densities. The system delivers these beams into an ultrahigh vacuum chamber equipped with a cylindrical mirror analyzer for in situ Auger electron spectroscopy measurements on samples after hydrogen isotope exposure, and a quadrupole mass analyzer for secondary ion mass spectroscopy measurements during hydrogen isotope bombardment. Ion energies range from 300 eV to 10 keV at flux densities of up to 3.6×1016 atoms/cm2 s over a 6-mm diam spot. The performance characteristics and analytical capabilities of the system are described. Representative sputtering data for Si by deuterium are given and other brief surface studies are described.
Theoretical evaluation of the temporal and spatial resolutions of Photochron streak image tubes
Authors: Niu H. , Sibbett W. , Baggs M. R.
Published: March 2003

A method involving modulation transfer functions has been used to study the temporal and spatial resolutions of Photochron streak tubes. This is shown to be a much more physically realistic and reliable approach for the evaluation of the temporal resolution of a streak camera than that based on the commonly applied Gaussian approximations. The results obtained from the temporal modulation transfer functions (TMTF) indicate that the increase of the electric field near the photocathode is an insufficient condition to ensure the best temporal resolution. It is also shown that there is an optimum streak speed for which the camera instrumental function is a minimum, and theoretical estimates are given for the Photochron I, II, and IV streak image tubes.
Bandpass x-ray diodes and x-ray multiplier tubes
Authors: Wang C. L.
Published: March 2003

We present a simple method of obtaining bandpass x-ray detectors. The lower and upper bounds of the bandpass are determined by the absorption edges of the photocathode and of the filter, respectively. Examples are given for windowless and vacuum bandpass x-ray diodes. Extension of the method to electron multiplier tubes is also presented.
Gas discharge ion source. IV. Further studies with the duopigatron
Authors: Bickes R. W. , O’Hagan J. B.
Published: March 2003

Experimental studies with a duopigatron gas discharge ion source are described; measurements of the ion current, mass and energy distributions, and current density profiles as a function of the aperture sizes of the source electrodes are reported. Larger aperture diameters were required to minimize damage to the original ion source [configuration described in Rev. Sci. Instrum. 49, 435 (1978)] observed during its operation on the Sandia Intense Neutron Source Target Test Facility. The ’’best’’ new configuration produces a 200-mA ion beam that contains 52% D+ at an arc current of 13 A. In addition to the performance measurements, extensive mass analyses of the ionic impurities produced inside of the ion source were carried out. The large aperture sources produce beams that contain approximately 0.5% contaminants. Typical mass spectra are described and the sources of the impurities discussed.
Microprocessor-controlled phase analysis for a 2-mm microwave interferometer on the TCA tokamak
Authors: Lister J. B. , Means R. W. , Oberson P.
Published: March 2003

The method of phase analysis is presented for a 2-mm microwave interferometer built to measure the plasma density in a tokamak. Use is made of a fast phase shifter (FPS) constructed from a switchable four-port circulator to resolve the phase ambiguity inherent in a simple interferometer. The phase between 0–2π is calculated by a microprocessor accessing a look-up table and the total phase is calculated by taking the 0 to 2π crossings into consideration. It is software controlled and the complete sampling and analysis cycle takes 24 μs which is sufficiently rapid for the application considered. The phase information is available in analog and digital form.
Production of a large diameter hot-electron plasma by electron cyclotron resonance heating
Authors: Kawai Y. , Sakamoto K.
Published: March 2003

A large diameter hot-electron plasma is produced by electron cyclotron resonance heating, using a slotted Lisitano coil as a launcher. It is found from detailed measurements of the plasma parameters that ne≲3×1011 cm−3 and Te≲40 eV, with a diameter ≊14 cm. High-energy tails with temperatures of more than 100 eV are observed.
LSI-11/2 microcomputer-based data-acquisition system for laser spectroscopy
Authors: Fisher Paula L. , Cone R. L.
Published: March 2003

A versatile data-acquisition system using a DEC LSI-11/2 microcomputer and interface routines written in the C programming language is presented. The system described is used to control laboratory equipment, take data, and perform computational tasks such as signal averaging. A major advantage of this system is its expandability.
Multidirectional photodiode array for the measurement of solar radiances
Authors: Davis J. M. , Vogel C. , Cox S. K.
Published: March 2003

An instrument designed to measure the angular variation of an incident radiance field is described. The instrument utilizes a multidetector design which views the incident radiance field from several angular positions simultaneously. A version of the instrument which utilized 13 silicon photodiode detectors has been constructed and used to collect data of interest to the meteorological community. The instrument was deployed on a high-altitude jet research aircraft to measure the angular variation of radiances reflected from various natural surfaces. Results are presented for measurements over desert, ice, and the windblown ocean surface. The description of the data analysis procedures is sufficiently general to allow application to any instrument of similar design. It is shown that for small values of experimental error ≃1%, the fields of view may be increased to 60° half-angle while maintaining an acceptable level of information content. If the fields of view are increased to 90° half-angle, only eigenfunctions associated with the three largest eigenvalues have acceptable information content. The multidetector design of the instrument greatly simplifies the data-collection process by eliminating the need for more expensive tracking or scanning hardware and, when data is collected from an aircraft platform, by eliminating the need for more complicated flight patterns.
Microcomputer system for acquisition and processing of video data
Authors: Oreb B. F. , Brown N. , Hariharan P.
Published: March 2003

A simple setup is described which uses a microcomputer to control the acquisition of video data by a large auxiliary random-access memory. This results in an inexpensive and versatile system which can be used where large amounts of data must be acquired at a high rate but can be processed subsequently at a lower rate.
New measurement of the Fano factor of mercuric iodide
Authors: Ricker G. R. , Vallerga J. V. , Dabrowski A. J. , Iwanczyk J. S. , Entine G.
Published: March 2003

We have measured a new upper limit to the Fano factor of mercuric iodide of 0.19±0.03. This new limit was achieved by slightly cooling the mercuric iodide x-ray detector and preamplifier to −20 °C so that the contribution to the full width at half-maximum due to charge collection efficiency was minimized. The new upper limit is part of a gradual trend toward a lower Fano factor as growing and fabrication techniques for mercuric iodide improve.
Plasma studies on a hollow cathode, magnetic multipole ion source for neutral beam injection
Authors: Goebel D. M. , Forrester A. T.
Published: March 2003

A series of Langmuir probe studies has been undertaken on the hydrogen plasma of an 8×8-cm extraction area hollow cathode, magnetic multipole ion source intended for use in neutral beam injection systems. Five movable probes were utilized to measure plasma density, electron temperature, plasma potential, and primary electron density as a function of position in the plasma generator and performance of the ion source. The measurements indicate that at discharge current below 150 A, a fairly uniform plasma over the source volume, with a potential positive with respect to the anode, is generated. The performance of the plasma generator at low currents resembles the filament discharge, magnetic multipole confinement ion source. The ion source in this case has good efficiency and plasma uniformity, but atomic species fractions of less than 70%. As the discharge current is increased, the plasma separates into a high-density, high-ionization, positive potential region near the cathode, and a lower-density, negative potential plasma near the extraction grids. This plasma near the acceleration electrodes is characterized by a relatively low primary electron to plasma electron density ratio of about 2%. The performance of the source significantly increases over the uniform volume plasma case with atomic species output of typically 85% and gas utilization efficiencies of 40%–65%. The high-current, hollow cathode discharge produces a plasma configuration and output performance similar to that of the duoPIGatron ion source, but with lower noise levels.
Sealed copper vapor laser assembly
Authors: Alger Terry W. , Benett William J.
Published: March 2003

Improvements in a discharge heated copper vapor laser (CVL) assembly may result in greater long term performance and reliability. This new design incorporates a positive gas seal to allow high-pressure sealed or controlled leak rate operation. High-pressure operation at low buffer-gas leak rates results in a decrease in copper loss rate and, because of this, an improved useful lifetime. A description of materials and construction method for this copper vapor laser assembly is provided.