bluuebunny/crossref_metadata_2025 huggingface dataset:
Compact electron-beam source for formation of neutral beams of very low vapor pressure materials
Authors: Rutherford J. A. , Vroom D. A.
Published: March 2003

An electron-beam heater and associated power supply have been developed for use in formation of metal vapors for neutral beam studies. The device is small with relatively low power (250 W). It is easily constructed and designed such that the target surface is normal to the direction of propagation of the neutral beam. Beams of tantalum atoms and carbon particles have been formed using the device.
Hemispherical dielectric permittivity cell
Authors: Hayden Joseph S. , Berberian John G.
Published: March 2003

A three-terminal dielectric cell based on a hemispherical design is constructed for low-temperature measurements of dielectric permittivity. The cell has a small sample volume, is geometrically stable, and shows no frequency dependence of capacitance. Measurements on test samples are presented showing both cell constant stability data and the linearity of measured capacitance with dielectric constant.
Steel pressure vessels for hydrostatic pressures to 50 kilobars
Authors: Lavergne A. , Whalley E.
Published: March 2003

Cylindrical steel pressure vessels are described that can be used for hydrostatic pressures up to 50 kilobars. Monoblock vessels of 350 maraging steel can be used to 40 kilobars and compound vessels with an inner vessel of 350 maraging steel and an outer vessel of 300 maraging steel to 50 kilobars. Neither requires the cylinder to be end loaded, and so they are much easier to use than the more usual compound vessels with a tungsten carbide inner and steel outer vessel.
Construction of parallel grids acting as semitransparent flat mirrors in the far infrared
Authors: Sentz A. , Pyee M. , Gastaud C. , Auvray J. , Letur J. P.
Published: March 2003

The construction of metallic wired grids used as semitransparent mirrors is described. The reflectance of such grids varies widely with the polarization direction of the beam. The measured characteristics are compared with those calculated. These grids are used in the cavity of an HCN laser and determine the polarization direction of the output beam.
Microwave ion source for high-current implanter
Authors: Sakudo Noriyuki , Tokiguchi Katsumi , Koike Hidemi , Kanomata Ichiro
Published: March 2003

A long-life, high-current, microwave ion source for an electromagnetic mass separator is described. Ionization takes place due to the 2.45-GHz microwave discharge at a magnetic field intensity which is higher than the electron cyclotron resonance magnetic field. The discharge chamber is a ridged circular waveguide. The discharge region is restricted to a rectangular volume between the ridged electrodes by filling the remaining portions with dielectric. This source operates under low pressure (10−2–10−3 Torr) and with high power efficiency. The incident microwave power is only several hundred watts at maximum output. When PH3 gas is introduced, the total extracted current is about 40 mA with a 2×40-mm extraction slit. A P+ ion implantation current of more than 10 mA is obtained by combining the source with a 40-cm radius, 60° deflection magnetic mass separator.
Calibration models for high enthalpy calorimetric probes
Authors: Kannel Arne
Published: March 2003

The accuracy of gas-aspirated liquid-cooled calorimetric probes used for measuring the enthalpy of high-temperature gas streams is studied. The error in the differential temperature measurements caused by internal and external heat transfer interactions is considered and quantified by mathematical models. The analysis suggests calibration methods for the evaluation of dimensionless heat transfer parameters in the models, which then can give a more accurate value for the enthalpy of the sample. Calibration models for four types of calorimeters are applied to results from the literature and from our own experiments: a circular slit calorimeter developed by the author, single-cooling jacket probe, double-cooling jacket probe, and split-flow cooling jacket probe. The results show that the models are useful for describing and correcting the temperature measurements.
Glass enclosed resistance thermometer for temperature measurement inside a high-pressure vessel
Authors: Trappeniers N. J. , Biswas S. N. , Klooster P. van’t
Published: March 2003

A method is described for the measurement of temperature inside a high-pressure vessel to 3000 bars. This involves enclosing a Pt resistance thermometer in a soft glass tube with sealed Pt contacts. resistance thermometer in a soft glass tube with sealed Pt contacts.
Low cost auxiliary system for broadband NMR on strongly magnetic systems
Authors: Nevald Rolf , Hansen Poul Erik
Published: March 2003

A low cost auxiliary system consisting of He cryostat, superconducting magnet, and sample holder assembly with field probe has been constructed. The system meets the requirements of NMR on strongly paramagnetic or ordered magnetic materials, which are accurate temperature settings over a wide range, high NMR frequencies, high and accurate magnetic fields of moderate homogeneity, and exact crystal orientations in the fields. The following values are achieved: The temperature setting in the range 1.7–400 K varies less than 0.5% for 10 min, which is the typical recording time of a spectrum. The distance from the NMR oscillator to the sample is only 55 cm (wavelength of ∼550 MHz radiation), giving a tolerable He evaporation rate of 0.35 l/h. The maximum field at 4.2 K is 43.2 kG, which can be measured with an accuracy better than ±100 ppm. The homogeneity at maximum field over a central sphere 8 mm in diameter is 5 G. The uncertainty on the crystal orientation in the field is ±1/2 degree.
Airborne lidar aerosol measurements during the ASSESS II mission
Authors: Werner Ch. , Bachstein F. , Dietz S. , Herrmann H. , Köpp F. , Löffler H.
Published: March 2003

During May 1977 the Airborne Science Spacelab Experiments System Simulation (ASSESS II) took place, using the NASA CV 990 aircraft. A ND:glass lidar system, measuring the aerosol mass concentration over large areas, was proxy operated by trained ’’Payload Specialists.’’ The main part of this paper is concerned with the lidar experiment and its results. The participants in the mission viewed it as a tool for judging their spacelab science management and as the final stage of a guide for future planning of experiments. A general result that has emerged is that, for a real spacelab mission, the handling of remote sensing experiments should be fully automatic.
Crossed grid anode and its image partitioning
Authors: Knapp Guenther
Published: March 2003

Measurements on an imaging crossed grid anode following a pair of microchannel plates indicate fast charge propogation via wire-to-wire capacitances, suggesting a temporal resolution of 100 ns. A figure of merit for partitioned systems has been suggested that provides an estimate of the position uncertainty of photoelectrons in the image plane of an anode. Solutions for two-, three-, and four-amplifier position algorithms are given, and basic system requirements are discussed.
Viscosity measurements in the diamond anvil pressure cell
Authors: Piermarini G. J. , Forman R. A. , Block S.
Published: March 2003

The viscosity of liquids can be measured in the diamond-anvil pressure cell utilizing a falling-solid sphere method and the ruby technique for pressure measurement. The pressure dependence of the viscosity of a 4:1 mixture (by volume) of methanol–ethanol was determined to 70 kilobars. The accuracy of the method is estimated from measurements made on a fluid of known viscosity.
Some new aspects of an alternating current demagnetization apparatus
Authors: Carrillo C. Roberto , Lozano Octavio , Pal Surendra
Published: March 2003

A combined mechanical–electronic system for a smooth linear control of the demagnetizing field is described. Actual demagnetizing curves obtained for some igneous rocks are given to illustrate good functioning of the apparatus in paleomagnetic research.
Balloon-borne photoionization mass spectrometer for measurement of stratospheric gases
Authors: Aikin A. C. , Maier E. J. R.
Published: March 2003

A balloon-borne photoionization mass spectrometer used to measure stratospheric trace gases is described. Ions are created with photons from high-intensity krypton discharge lamps and a quadrupole mass analyzer is employed for ion identification. Differential pumping is achieved with liquid helium cryopumping. To insure measurement of unperturbed stratospheric air, the entire system is contained in a sealed gondola and the atmospheric sample is taken some distance away during descent. The photoionization technique allows the detection of a low ionization potential constituent, such as nitric oxide, at less than a part in 109 in the presence of the major atmospheric gases and their isotopes. Operation of the mass spectrometer system was demonstrated during a daytime flight from Palestine, Texas on 26 April 1977. The sensitivity achieved and the unique selectivity afforded by this technique offer a capability for trace constituent measurement not possible with the more conventional electron impact ionization approach.
High-level noise source for the calibration of Johnson noise power thermometers
Authors: Blalock T. V. , Borkowski C. J.
Published: March 2003

A new high-level noise source was developed specifically for the calibration of Johnson noise power thermometers (JNPT), but it is useful in other applications requiring a stable, wideband, well-defined noise power spectral density. The design concept for the noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of an inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise of a 100-Ω resistor at a temperature of about 64 000 K. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 dB) in the frequency range 1–150 kHz which brackets typical passbands of the signal-processing channels of JNPTs. The noise source was evaluated by comparing its output noise power with the thermal noise power generated by a platinum resistor of known ohmic value at the temperature of the aluminum freezing point (933.52 K). The measured noise power was within 0.06% of the value computed from the fundamental thermal noise equation of Nyquist. The power spectral density varies less than 0.03% for ambient temperature fluctuations in the range 15°–35°C.
Multiwire proportional chamber system of the Fermilab single arm spectrometer
Authors: Anelli E. F. , Chiaradia M. T. , De Marzo C. , Distante A. , Favuzzi C. , Ferorelli R. , Germinario G. , Guerriero L. , La Vopa P. , Maggi G. , Perchiazzi M. , Posa F. , Sacchetti A. , Selvaggi G. , Spinelli P. , Waldner F.
Published: March 2003

We describe a system of two groups of multiwire proportional chambers and its special purpose interface used in the Single Arm Spectrometer (SAS) facility at Fermilab. The first set measures the coordinates of the fast particle going into the spectrometer arm with a space resolution down to ±0.5 mm. The second set, close to the target, measures the multiplicity and angular distributions of charged particles coming from the interaction. The chambers of this set have three sensitive planes with wires at 120° in the same gas volume to measure three coordinates for each physical point, two readout channels per wire to minimize the inefficiency due to the very high flux and insensitive regions at the center of the chambers where they are crossed by the beam.
ENDOR cavity for electron spin echo experiments
Authors: Davis J. L. , Mims W. B.
Published: March 2003

A microwave cavity is described for performing ENDOR measurements in conjunction with electron spin echo experiments. The frequency of the cavity is ≃9.4 GHz and the Q value ≃80. Both of these parameters can be changed by making small alterations in the design. The radio-frequency magnetic field is confined to a small volume in order to minimize inductance and maximize the field strength obtainable for a given current. Direct measurements show the field in the sample to be ≃11 G/A of coil current in a typical case. This corresponds to a field ≃8 G in the rotating frame per ampere of coil current.
Thermal sensitive paper as a diagnostic for intense relativistic electron beam dynamics
Authors: Gilgenbach R. M. , McDermott D. B. , Marshall T. C.
Published: March 2003

Thermal sensitive paper has been used as a diagnostic for an intense relativistic electron beam propagating in a rippled magnetic field. The Er×Bz rotation of the beam has been measured from the exposed pattern on the thermal paper and used to calculate the electrostatic field of the beam Er, and the corresponding values of electron density and beam current. Exposed strips of thermal paper show longitudinal modulation of the radial electron velocity with a period corresponding to that of a rippled magnetic field; modulation of the radial electron velocity at the cyclotron frequency has also been observed.
Bandpass (bandstop) digital filter design routine
Authors: Kaiser J. F. , Reed W. A.
Published: March 2003

As a complement to the design methods for low pass digital filters previously published [Rev. Sci. Instrum. 48, 1447 (1977)], we present a description of a bandpass (or bandstop) digital filter design program, a demonstration of its use, and the fortran code.
Design and construction of a temperature wave generator
Authors: Lee Tay-How , Gille John C.
Published: March 2003

A sinusoidal temperature wave generator has been developed and constructed. It consists of a cold plate, a heating coil, and an electronic feedback control with a thermocouple sensor. The design criteria, heating and cooling calculations, and electronic and mechanical construction details are presented and described. Results are shown, and possible modifications are discussed.
Power and energy measurements of transient electric discharge
Authors: Kono Michikata , Iinuma Kazuo , Kumagai Seiichiro
Published: March 2003

A simple and inexpensive calculating device for electrical power and energy of transient electric discharges is described. The calculation is made by multiplication of the voltage and current of the discharge by use of wideband integrated circuits.
New technique for single-scan T1 measurements using solid echoes
Authors: Burum D. P. , Elleman D. D. , Rhim W. K.
Published: March 2003

A simple technique for single-scan T1 measurements in solids is proposed and analyzed for single exponential spin–lattice relaxation. In this technique, the direct spin heating caused by the sampling process is significantly reduced in comparison with conventional techniques by utilizing the ’’solid echo’’ to refocus the magnetization. The applicability of this technique to both the solid and liquid phases is demonstrated.
Analog analysis of exponential decays using a transient recorder
Authors: Jousset Maurice , Thusius Darwin
Published: March 2003

An analog computation technique is described for the determination of amplitudes and time constants of one or two exponentials captured with a transient recorder. The method is based on operator-controlled processing of the periodic analog output of the recorder with log-antilog circuitry. In many cases the accuracy of the analysis approaches that obtained with numerical curve fitting procedures.
Multicomponent frequency shifting self-aligning laser velocimeters
Authors: Rizzo J. E. , Halliwell N. A.
Published: March 2003

A design using simple lenses and frequency shift by scattering disk has been developed, which allows easy construction, and alignment of one-, two-, and three-orthogonal-component, frequency shifting laser Doppler velocimeters. A series of instruments designed on this basis have proved to be inexpensive to construct, precise and accurate to use, adaptable to a wide range of applications, and have proven particularly advantageous in studies of turbulent phenomena and complex flows. In this paper the design concept is explained, construction and alignment procedures are outlined for the simplest assembly of the one and two component versions, and performance and application examples are presented. The extension of the system to measure the third orthogonal component is discussed.
Performance characteristics of high-conductivity channel electron multipliers
Authors: Timothy J. G. , Bybee R. L.
Published: March 2003

A new type of channel electron multiplier (CEM) has been developed which utilizes a high-conductivity glass to provide a very high count -rate capability. A linear response to count rates in excess of 2×106 count s−1 has been demonstrated with no measureable change in the detection efficiency at total accumulated signal levels of greater than 2×1011 counts. The measured loss of gain at 2×1011 accumulated counts was less than 20%. The cathode configuration of the CEM is optimized for maximum sensitivity at xuv wavelengths and detection efficiencies greater than 20% have been obtained using opaque MgF2 cathodes at wavelengths between about 150 and 800 Å.
Analyzer system capable of determining energy and direction of charged particles in ultrahigh vacuum
Authors: Allyn C. L. , Gustafsson T. , Plummer E. W.
Published: March 2003

We have constructed and tested a system capable of measuring the energy of charged particles emitted from a sample at any angle relative to the sample or the incident beam of exciting particles. The energy analysis is accomplished by a 180° spherical deflecting-type analyzer, operated at constant pass energy with a series of electrostatic lenses. The analyzer system is properly apertured to accept incoming particles from a spot of 1.5 mm diameter at the sample and within a cone of 2.5° half-angle. The lens system used has constant transmission independent of the incident energy. The energy analyzer is independently rotatable about two orthogonal axes, giving it complete freedom of access to any angle of collection relative to the sample orientation. The sample can rotate about two orthogonal axes so that any angle of incidence can be used. Specific examples are given of the performance of the system when used for the measurement of the angular distribution of photoelectrons excited by synchrotron radiation.
Flat-response, subkiloelectronvolt x-ray detector with a subnanosecond time response
Authors: Kornblum H. N. , Slivinsky V. W.
Published: March 2003

A detector that has a flat response to x rays with energies between 100 eV and 1.5 keV has been built. It has been used to measure x rays emitted from gold disks irradiated by the Argus laser at Lawrence Livermore Laboratory. Results from this detector are in good agreement with results from other techniques.
Broadband stable detector for ultraviolet (300–1700 Å) plasma spectroscopy
Authors: Richards R. K.
Published: March 2003

A CuI coating on the first dynode of a windowless photomultipler creates a broadband and stable detector for ultraviolet plasma spectroscopy with a quantum efficiency above 2% from 400 to 1600 Å. The stability of this photocathode was tested in the environment of tokamak discharges; no degradation was found after one year’s use.
Decoding unstable FSK modulated signals
Authors: Richner Hans , Phillips Peter D.
Published: March 2003

When a phase locked loop (PLL) is used for decoding FSK (frequency shift keying) modulated signals its output is very sensitive to even slight changes of the ’’mark’’ and ’’space’’ frequencies which—by international convention—are rather close together. The use of a nonstandard circuit around the PLL can improve greatly its ability to properly decode distorted or poorly modulated FSK signals.
Apparatus for phase transformation of glassy materials in steep thermal gradients
Authors: Sanampudi Kondala Rao , Risbud Subhash H.
Published: March 2003

The design and fabrication of an apparatus for phase transformations under steep (≈600°C/cm) thermal gradient conditions is described. Applications in controlled recrystallization of glassy phases and crystal growth are discussed.
Ultrahigh vacuum chamber for Raman studies of gases adsorbed on metals
Authors: Stencel J. M. , Noland D. M. , Bradley E. B. , Frenzel C. A.
Published: March 2003

An ultrahigh vacuum chamber is described which is being used to study laser Raman spectra associated with gas adsorption on clean metal surfaces. The system enables sample temperatures from -85° to 600°C to be obtained, and besides surface cleaning capabilities associated with high-temperature oxidation or reduction, it incorporates an Ar+ sputter gun for surface cleaning. Initial experiments of CO+H2 adsorption on crystalline Ni surfaces are described and the effects of H2 and O2 exposure shown for the 80 cm−1 band which results from CO+H2 adsorption.
Laser flash method for measuring thermal conductivity of liquids—application to low thermal conductivity liquids
Authors: Tada Yutaka , Harada Makoto , Tanigaki Masataka , Eguchi Wataru
Published: March 2003

A laser flash method developed for the measurement of thermal conductivity of solids was applied to liquids of low thermal conductivity. The sample liquid was sandwiched in between a small thin metal disk and a sample holder. When the laser beam is absorbed in the front surface of the metal disk, the temperature of the disk quickly rises about 2 K and heat then flows downwards through the sample liquid as one-dimensional heat flow. The thermal conductivity of liquid can be obtained from the temperature fall of the disk without employing any reference materials and also without measuring the thickness of the sample liquid layer. Thermal conductivities of water and toluene near room temperature were measured by this method with a mean deviation of 2.6%. This laser flash method may be applied to the measurement of the thermal conductivity of liquids such as molten salts at elevated temperatures.
Improved high-intensity microwave discharge lamp for atomic resonance absorption and fluorescence spectrometry
Authors: Lifshitz Assa , Skinner Gordon B. , Wood David R.
Published: March 2003

An unusually good combination of high intensity and narrow line has been achieved in a microwave discharge lamp by placing the optical window in the center of the microwave cavity. Construction details and performance characteristics are described.
Molecular ion source having low energy spread and single-electron-impact excitation
Authors: Spezeski Joseph J. , Ruff George A. , Wing William H.
Published: March 2003

A cylindrically symmetric electron-bombardment ion source is described that has been useful in beam experiments with molecular ions. Measurements indicate that the ions have a kinetic-energy spread (full-width at half-maximum) of 0.5–1.0 eV, a current of several microamperes, and a population distribution that is consistent with vibrational and rotational factors resulting from single-electron-impact ionization. The source exhibits low noise (≲ twice the theoretical shot-noise limit) and has a compact and easily serviceable construction.
Observation and removal of higher-order (ghost) energy-loss lines present in Möllenstedt electron velocity analyzers
Authors: Rueckner W. H. E. , Barlas A. D. , Wellenstein H. F.
Published: March 2003

Möllenstedt electron velocity analyzers, used in high-energy electron impact spectroscopy, have been found to be limited by higher-order (ghost) energy-loss lines superimposed upon the real energy-loss spectrum. The origin of these ghost lines, as well as a method of removing them experimentally, is discussed.
Pulsed acousto-optical modulator driver
Authors: Jones E. D. , Franklin F. R. , Palmer R. E. , Padrick T. D.
Published: March 2003

A gated rf driver for an acousto-optic modulator used to actively mode-lock a laser is described. The modulator is driven in a pulsed mode, so that much higher rf power can be applied to obtain high modulation indices.
Manual ellipsometry made semiautomatic
Authors: Melmed A. J. , Carroll J. J.
Published: March 2003

A simple, inexpensive mechanical device is described that was designed to provide more effective data acquisition and to fit onto an already existing polarizer wheel drive mechanism of a commercially available, manual ellipsometer. A gas/metal adsorption experiment is used to illustrate typical results. Use procedures are detailed.
Platinum wire NMR thermometer for ultralow temperatures
Authors: Buchal C. , Hanssen J. , Mueller R. M. , Pobell F.
Published: March 2003

We report on the construction and behavior of a platinum wire NMR thermometer. The thermometer has been calibrated down to 14.6 mK, and used down to 0.55 mK; the latter temperature has been achieved by nuclear demagnetization of PrNi5.
High sensitivity image intensifier-TV detector for x-ray diffraction studies
Authors: Reynolds Geo. T. , Milch J. R. , Gruner S. M.
Published: March 2003

A sensitive, efficient image intensifier-TV x-ray detector is described that has been optimized for a large class of diffraction studies of biological structures. All of the major components are commercially available. The system is well suited to measuring the intensity of diffraction patterns that are weak, or changing with time. Because there is no count rate limitation, it is particularly well suited for studies utilizing the high fluxes of synchrotron sources.
’’NODUS’’—a sensitive new instrument for analyzing the composition of surfaces
Authors: Brongersma H. H. , Hazewindus N. , van Nieuwland J. M. , Otten A. M. M. , Smets A. J.
Published: March 2003

A novel type of ion-scattering spectrometer for analyzing the composition of surfaces is described. By means of a specially designed cylindrical mirror analyzer the sensitivity of the instrument is increased by two or three orders of magnitude as compared with that of equipment used hitherto. The increased sensitivity allows analyses to be performed using extremely low ion doses. Under these conditions, destruction of the surface is negligible. The use of a differential pumping system guarantees UHV conditions at the target, thus minimizing contamination.
Automated luminescent topographic system
Authors: Luciano Michael J. , Kingston D. L.
Published: March 2003

A new optical-scanning technique with a spatial resolution of 10 μm has been developed for the observation of surface luminescence. The photoluminescence topographic technique is a fully automated system capable of measuring luminescence intensity from a surface area as large as 25.8 cm3 as well as the actual luminescence spectra from a spot as small as 10 μm in diameter. The system consists of an Ar-ion laser for excitation, a bidirectional scanner with focusing lens, a spectrometer for high spectral resolution, and a photomultiplier for photon counting. Experimental control and data acquisition and display are performed by a Hewlett-Packard 9820A calculator and interface package. Applications of the technique in the analysis of impurity segregation in semiconductor wafers are illustrated.
Fiber optic heterodyne interferometer for vibration measurements in biological systems
Authors: Nokes Mark A. , Hill Bruce C. , Barelli Anthony E.
Published: March 2003

An optical heterodyne interferometer utilizing a fiber optic target probe and a digital phase compensation system is described. Optical performance and the effect of background motions on output are described. Maximum sensitivity for a simulated biological target in aqueous medium is 0.05 Å Hz−1/2 for a signal-to-noise ratio of unity.
Efficient, high-spectral-resolution Bragg crystal x-ray polarimeter
Authors: Doyle B. L. , Schiebel U. , Ellsworth L. D. , Macdonald James R.
Published: March 2003

Utilizing Bragg scattering near 90°, an x-ray polarimeter is described that has high spectral resolution and reasonable efficiency. The latter is achieved by using a position-sensitive proportional counter to discriminate spatially resolved x rays dispersed by the crystal. This instrument has been used to measure the linear polarization of lines from one- and two-electron oxygen ions. For this study, aligned initial states have been populated in oxygen beams by various excitation processes in foil, gas, and thick solid targets. In spite of the small probability for the production and radiative decay of few-electron excited states in the presence of intense background radiation, the instrument resolution and efficiency are sufficient to permit polarization measurements.
Improved method for minimizing vibrational motion transmitted by pumping lines
Authors: Kirk W. P. , Twerdochlib M.
Published: March 2003

A description is given for a technique that is very effective in reducing vibrations transmitted along large-diameter (≳8 cm) vacuum and gas pumping lines. This technique uses a supported double-gimbal metal bellows design. When compared with other techniques such as the crossed T metal bellows design, a factor of 7 improvement was measured. An analysis is included which compares the various techniques, and shows that, in principle, improvement factors as high as 80 or more can be realized with the double-gimbal design.
High-power CO2 laser-beam monitor
Authors: Grosjean Dennis F. , Olson Robert A. , Sarka Benjamin , Rabe Douglas C.
Published: March 2003

A diagnostic system for measuring the beam power and quality of a high-power cw CO2 electro-aerodynamic laser is described. A ZnSe beamsplitter was employed to split off a small fraction (0.5%) of the main laser beam for diagnostic purposes. The low-power beam was split again to provide two beams for power and energy-distribution measurements, concurrent with sample irradiation by the main beam. An electrically calibrated disk calorimeter was used to measure beam power. The temporal and spatial energy distributions were measured by means of a mechanically scanned, one-dimensional pyroelectric array. This provided a 16×16 element two-dimensional map of the beam profile at a rate of up to 10 Hz.
Liquid helium cryopump and reliable opening device for a balloon-borne mass spectrometer
Authors: Ingels J. , Arijs E. , Nevejans D. , Forth H. J. , Schäfer G.
Published: March 2003

The design, technical characteristics, and test and flight results of a liquid helium cryopump and an opening device operating on board a balloon-borne mass spectrometer combining a cryopump and a quadrupole mass filter are reported. The gas inlet of this mass spectrometer is opened through a simple and reliable remote-controlled system, which is also described.
Automatic NMR field-frequency lock—pulsed phase locked loop approach
Authors: Kan S. , Gonord P. , Fan M. , Sauzade M. , Courtieu J.
Published: March 2003

A self-contained deuterium frequency-field lock scheme for a high-resolution NMR spectrometer is described. It is based on phase locked loop techniques in which the free induction decay signal behaves as a voltage-controlled oscillator. By pulsing the spins at an offset frequency of a few hundred hertz and using a digital phase-frequency discriminator this method not only eliminates the usual phase, rf power, offset adjustments needed in conventional lock systems but also possesses the automatic pull-in characteristics that dispense with the use of field sweeps to locate the NMR line prior to closure of the lock loop.
Pressure jump method with detection of optical rotation and circular dichroism
Authors: Gruenewald Bernd , Knoche Wilhelm
Published: March 2003

A pressure jump technique for fast kinetics using optical rotation and circular dichroism detection is presented and a suitable cell design for both detection methods is discussed. The detectability of changes in optical rotation far away from the Cotton region is considered, and measurements made on a pressure-dependent folding reaction of the protein serum albumin are given as an application.
Viking gas chromatograph–mass spectrometer
Authors: Rushneck D. R. , Diaz A. V. , Howarth D. W. , Rampacek J. , Olson K. W. , Dencker W. D. , Smith P. , McDavid L. , Tomassian A. , Harris M. , Bulota K. , Biemann K. , LaFleur A. L. , Biller J. E. , Owen T.
Published: March 2003

The Mars viking gas chromatograph–mass spectrometer is described. The system is designed to determine the composition of the Martian atmosphere and detect and identify chemical compounds vaporized or pyrolyzed from the Martian soil. Construction details, performance data, data processing methods, and references to manufacturing and test procedures are also provided.
Noninvasive beam-wave reflectometric instrumentation for measuring complex permittivity of dielectric materials at microwave frequencies
Authors: Neelakantaswamy P. S.
Published: March 2003

A noncontact and nondestructive method of measuring at microwave frequencies the complex permittivity of a selected region in a dielectric slab is described. For this purpose the test dielectric sample is irradiated with a focused (gaussian) microwave beam by means of a suitable applicator. From the characteristics of the reflected beam wave measured at a reflectometric bridge arrangement, the complex permittivity of the exposed region is determined. Some theoretical and experimental results analysing the test conditions are presented. Application of this method to biological in vivo (or in vitro) measurements of dielectric properties of bones and tissues, with selective partial-body microwave irradiation, is discussed.
Simple manipulator for rotating spheres
Authors: Weinstein B. W. , Hendricks C. D. , Ward C. M. , Willenborg D. L.
Published: March 2003

We describe a simple device for rapidly rotating a small sphere to any orientation for inspection of the surface. The ball is held between two small, flat surfaces and rolls as the surfaces are moved differentially parallel to one another.
Identification of a previously undetected source of systematic error in capillary viscometry measurements
Authors: Wedlake G. D. , Vera J. H. , Ratcliff G. A.
Published: March 2003

A new analysis of the factors affecting the driving head within a capillary viscometer has identified a previously undetected source of error due to surface tension. In contrast to the well-known capillary rise correction to the effective driving head, this additional effect requires that a correction be made to the apparent head of liquid. Calculations show that this source of error may be responsible for deviations in experimental results as large as 1%. A new calibration equation which compensates for both surface tension effects is recommended.
Actively mode-locked and Q-controlled Nd:glass laser
Authors: Tomov I. V. , Fedosejevs R. , Richardson M. C.
Published: March 2003

A Q-controlled Nd:glass ring laser system has been developed which is actively mode-locked by means of either KD*P or LiNbO3 electro-optic modulators and is capable of producing 1.5 mJ, 100 ps, 1.06 μm pulses synchronized to better than 400 ps to an external event. By using prelase methods or saturable absorbers shorter pulses from 37 to 15 ps duration can be generated with poorer synchronization.
High-temperature dilatometer system for measuring the shrinkage kinetics of a liquid-containing ceramic system
Authors: Sandison R. D. , Eggerding C. L.
Published: March 2003

A dilatometer system usable to 1600°C in atmospheres varying from oxidizing to reducing, with or without controlled dew points, is described. The system was optimized to measure the shrinkage of a liquid-containing ceramic material without causing deformation by viscous creep. Shrinkages up to 20% may be measured continuously during a heating cycle.
Intense source of spin-polarized electrons
Authors: Hodge L. A. , Dunning F. B. , Walters G. K.
Published: March 2003

Spin angular momentum conservation in chemiionization reactions involving optically oriented He(23S) atoms in a flowing helium afterglow has been exploited to yield a source of spin-polarized electrons. Either transversely or longitudinally polarized electrons can be extracted. Polarized electron beam currents of ∼2 μA have been realized at 40% polarization. The beam has an effective emittance of ∼2 mrad/cm over the energy range 100–400 eV, an energy spread of ≲0.15 eV, and the polarization is readily reversible. The source is relatively inexpensive and appears suitable for the majority of low-energy spin-dependent scattering experiments proposed to date.
Broadband electrostatic acoustic transducer for ultrasonic measurements in liquids
Authors: Cantrell John H. , Heyman Joseph S. , Yost W. T. , Torbett M. A. , Breazeale M. A.
Published: March 2003

A broadband capacitive electrostatic acoustic transducer (ESAT) has been developed for use in a liquid environment at megahertz frequencies. The ESAT basically consists of a thin conductive membrane stretched over a metallic housing. The membrane functions as the ground plate of a parallel plate capacitor, the other plate being a dc biased electrode recessed approximately 10 μm from the electrically grounded membrane. An ultrasonic wave incident on the membrane varies the membrane–electrode gap spacing and generates an electrical signal proportional to the wave amplitude. The entire assembly is sealed for immersion in a liquid environment. Calibration of the ESAT with incident ultrasonic waves of constant displacement amplitude from 1 to 15 MHz reveals a decrease in signal response with increasing frequency independent of membrane tension. The use of the ESAT as a broadband ultrasonic transducer in liquids with a predictable frequency response is promising.
Mott electron spin polarization analysis system of novel design
Authors: Hodge L. A. , Moravec T. J. , Dunning F. B. , Walters G. K.
Published: March 2003

A novel Mott polarization analysis system is described. This system is much simpler than earlier designs and offers improved rejection of electrons inelastically scattered from the gold target foil. In addition the analyzer is capable of ’’in-line’’ polarization measurements.
Fast, large-signal, free-standing foil bolometer for measuring ultrasoft x-ray burst fluence
Authors: Degnan James H.
Published: March 2003

A fast (∼300 ns), large-signal (≳1 V), free-standing foil bolometer was developed for measuring ultrasoft x-ray burst fluences. The results of bolometer measurements of the radiation output of an imploding foil liner plasma indicate yields of several tens of kJ, assuming isotropic emission. This is in substantial agreement with filtered metal photocathode (x-ray diode) measurements. The bolometer design, response function, and comparison with x-ray photodiode data are discussed. This type of bolometer is particularly applicable to radiation measurements of high-energy, destructive pulsed plasmas such as high-energy imploding liner plasmas.
Laser-heated emission of electrons from a carbon-coated metal surface and its application to the emissive probe measurements
Authors: Ono S. , Teii S.
Published: March 2003

An electron source utilizing the CO2 laser-heated electron emission from a carbon-coated metal surface has been experimentally studied. This type of emission may have the advantage that no potential gradient exists in the vicinity of the metal surface and emission from a surface of very small dimension and of arbitrary shape can be easily obtained. Experimental emission current characteristics for various target temperatures were given and discussed. An application to the emissive probe for measuring the plasma space potential is shown. The results obtained by the emissive probe are also checked independently by using the rf probe method.
Time-of-flight photoelectron spectroscopy of gases using synchrotron radiation
Authors: White M. G. , Rosenberg R. A. , Gabor G. , Poliakoff E. D. , Thornton G. , Southworth S. H. , Shirley D. A.
Published: March 2003

A gas-phase time-of-flight (TOF) photoelectron spectrometer has been developed for use with synchrotron radiation. The excellent time structure of the synchrotron radiation at the Stanford Positron Electron Accelerator Ring (SPEAR) has been used as the time base for the TOF measurements. The TOF analyzer employs two multichannel plates (MCPs) in tandem as a fast electron multiplier with a matched 50-Ω anode to form an electron detector with a timing resolution of ⩽70 ps. The spectrometer is presently capable of analyzing electrons over a wide energy range (1–50 eV) at medium energy resolution (⩽5%) and high angular resolution (±3°).
Multiparameter system for investigation of the effects of high-power ultrasound on metals
Authors: Mignogna Richard B. , Green Robert E.
Published: March 2003

A multiparameter system has been developed which, for the first time, permits simultaneous measurement of sufficient quantities to test all of the proposed mechanisms for the influence of high-power ultrasound on metal specimens. Results of measurements using this system give new insight into the mechanical and thermal processes involved. Data are presented which show typical results obtained during tensile elongation of polycrystalline and single-crystal aluminum specimens.
Nuclear susceptibility thermometry using enriched 119Sn
Authors: Babcock J. , Kiely J. , Manley T. , Weyhmann W.
Published: March 2003

Tin enriched to 84.5% 119Sn has been used for static nuclear susceptibility thermometry. A calibration in the 2–40 mK range shows that it is linear in T−1 quite accurately from 2 to 15 mK. The thermometer is easy to use and responds rapidly.
Direct continuous measurements of thermal expansion coefficients of liquids and solids using flow microcalorimetry
Authors: Fortier Jean-Luc , Simard Marc-André , Picker Patrick , Jolicoeur Carmel
Published: March 2003

A differential heat capacity flow microcalorimeter is used to monitor in a continuous mode the thermal expansion of a sample during a programmed temperature scan. The sample may consist of liquids, suspensions, or bulk solids in a confining liquid and the typical temperature scanning rate is of the order of 1 K/min. The technique has a precision better than 1% and a detection limit of 10−6 ml s−1. In contrast to conventional dilatometers, this technique offers variable sensitivity and is not limited by the magnitude of the total volume change during the experiment. Various expansibility data obtained in the temperature range 10–55 °C are reported for several systems, namely water, benzene, carbon tetrachloride, and aqueous solutions of sodium chloride. The volume changes for the thermal transition of Teflon and the phase separation of 2-butoxyethanol/water mixtures further illustrate the possibilities of this new technique.
Novel sample container for solution calorimetry
Authors: Raschella D. L. , Fellows R. L. , Peterson J. R.
Published: March 2003

A new design for calorimeter sample containers is described. The basic design is a hollow right cylinder with thin, glass membranes covering both ends. The membranes are intended to be broken out completely to release the sample contained within. The membranes are sealed to the container body with silicone rubber. The sample containers are easily fabricated, have highly reproducible volumes, and are surprisingly durable. Even though the membranes are fragile, the design permits considerable handling of the container with impunity.
Low jitter, low inductance solid dielectric switches
Authors: Guenther A. H. , Strickland D. M. , Bettis J. R.
Published: March 2003

It has been shown that the use of graded solid dielectric sandwiches in laser-triggered spark gaps (LTS) can lead to highly desirable multichannel operations while maintaining the low delay and jitter performance characteristics of LTS. As many as ten separate breakdown channels were observed when small circular or hexagonal aluminum inserts were inserted between two Mylar dielectric sheets stressed at 4.1 kV/mil. A reduction in rise time was noted for these multichannel switching events.
Boxcar controller for low-repetition-rate use
Authors: Cooke W. E. , Gallagher T. F.
Published: March 2003

We present a simple digital circuit which will control a Princeton Applied Research Corporation (model No. 164) boxcar integrator and thereby allow full utilization of the linear sum mode. This provides for improved signal-to-noise ratios and shorter data acquisition times for short signals [10–50 ns occuring at moderate repetition rates (1–20 Hz)]. This provides significant data acquisition time savings for low-repetition-rate, high-time-resolution measurements. It also increases the signal-to-noise ratio in many circumstances.
New Kerr cell for low-temperature measurements
Authors: Crossley J. , Morgan B. K. , Rujimethabhas M.
Published: March 2003

A Kerr cell has been constructed which can be used to study the Kerr effect in liquids from room temperature down to 77 K. At low temperatures, the cell windows are free of moisture. The cell has been tested and measurements on liquid carbon disulfide, between 170 and 300 K, are discussed.
Precooling of a superconducting magnet using a cryocooler and thermal switches
Authors: Yamamoto Junya , Yanai Masayoshi
Published: March 2003

A simple precooling system for a superconducting magnet is developed using a Cryomech GB02 cryocooler and gas filled thermal switches. A superconducting magnet (NbTi wire, 7 T of maximum field, 5.6 kg of weight) is precooled to 16 K in about 70 h without any manual control. Heat transfer rate of each thermal switch (H2 or N2 gas filled at 1.3 MPa at room temperature) is about 3×10−1 W/K during the ON state, and 5×10−3 W/K during the OFF state.
Superconducting helically wound magnet for the free-electron laser
Authors: Elias L. R. , Madey J. M.
Published: March 2003

Theoretical and experimental studies conducted by the Stanford Free Electron Laser group have resulted in the first operation of a free-electron laser amplifier and free-electron laser oscillator. Two superconducting helically wound periodic magnetics have been constructed for use with the laser. In this paper we present a discussion of design considerations and test results for the two magnets. The tests included measurement of the magnitude and the variation of the transverse magnetic field with radius in the bore of the magnets, the critical current, and the intensity, angular distribution, and spectrum of the spontaneous radiation emitted by electrons moving through the field.
Automatic continous frequency calibration for super-regenerative oscillators used in nuclear quadrupole resonance
Authors: Murgich Juan
Published: March 2003

A new and improved method for continuous frequency calibration of the super-regenerative oscillator spectrum is described. The arrangement employs a Hewlett–Packard Model HP5345A reciprocal frequency counter capable of measuring the carrier frequency of rf pulses. The counter gate time is externally controlled via the quench pulses. High-resolution measurements are obtained through the use of the frequency-averaging mode provided by the counter. Three successive digits are displayed on a two-channel recorder using a digital-to-analog converter along with the lock-in output. This method provides automatic and continous high-accuracy frequency calibration of the spectrum which is independent of the rf level, quench frequency, and FM amplitude.
Conversion of a Cary 60 spectropolarimeter into a fast circular dichroism instrument for use with standard rapid reaction techniques
Authors: Bächinger H. P. , Eggenberger H. P. , Hänisch G.
Published: March 2003

The conversion of a Cary 60 spectropolarimeter to a fast circular dichroism instrument (CD) using CD detection for standard rapid reaction techniques and for recording normal CD spectra is described. Although the optical setup remains nearly the same, the electronics are modified to increase the frequency response. The use of a 18-kHz piezo-optical birefringence modulator allows measurements of relaxation times down to 5 ms. As an example of the kind of data obtainable with this instrument, measurements are presented on the acid denaturation of hemoglobin in the time range of 100 ms.