bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic Emission Test Facility
Authors: James Darrell R. , Carpenter Steve H.
Published: February 2004

An acoustic emission test facility was designed and constructed to allow constant strain rate compressive deformation of samples up to an applied load of approximately 180 kg. Strain rates of from 1.6×10−3 to 3.2×10−6 sec−1 were obtained with total system noise limited to less than 10 μV peak-to-peak referred to the input of the pre-amplifier. Over-all signal amplification was 9900±100 over a bandwidth of 200 Hz–200 kHz.
A Technique for Precision Measurements of Elastic Surface Wave Properties on Arbitrary Materials
Authors: Tittmann B. R.
Published: February 2004

A technique is described for determining both the elastic surfce wave velocity and its temperature coefficient. The technique can be used on very small samples and is not restricted to any particular class of materials, such as piezoelectrics. It employs an adaptation of the old method of acoustic wave generation with a dc pulse rather than an rf signal applied to a piezoelectric transducer. The generator and receiver transducers are very small chips, approximating point sources, and at the receiver the vertical component of particle velocity is measured as a function of time enabling one to distinguish clearly between various types of surface modes, e.g., Rayleigh wave, pseudosurface wave, Lamb wave, etc. The technique yields absolute surface wave velocities accurate to 0.2% and is readily adaptable to the use of the sing-around technique for measuring relative changes in the sound velocity as small as 1 ppm.
The p-n-p Transistor Used Exponentially to Linearize the Voltage Output of the PCO2 Physiological Electrode
Authors: Hahn Clive E. W.
Published: February 2004

A silicon diffused transistor, connected in the transdiode mode, is utilized to generate the antilogarithm of the commercial Severinghaus type Pco2 electrode. Operational amplifier requirements are discussed and a new single point calibrating procedure is introduced. A theoretical relationship for output errors is discussed.
Compact Pulsed HF Lasers
Authors: Ultee C. J.
Published: February 2004

A compact electrically pulsed HF laser is being described. The laser operates on a mixture of SF6 and H2 with 0.06 J energy, 25 kV pulses with a repetition of 100 pulses/sec. The output consists of the P(1)–P(7) rotational lines of the 1–0 vibrational transition and the P(2)–P(9) lines of the 2–1 transition. Line selection is provided by using a plane 300 line/mm grating as one reflector; the other reflector is an Irtran 4 flat used as a semitransparent mirror. Average power in all lines is 20 mW. Peak pulse power in individual lines is 15–20 W. Average and pulse power show good stability. The laser provides a convenient and compact source of ir radiation in the 2.5–3.0 μ region.
Hydroacoustic Image Transducer
Authors: Knollman G. C. , Brown A. E.
Published: February 2004

A solid state, linear array piezoelectric acoustic image converter is described which has been developed for realtime underwater viewing, especially in turbid and/or turbulent oceanic environments. Sensitivity and resolution of the acoustoelectric transducer are on the order of 10−11 W/cm2 and 1 mm, respectively, at a frequency of 2.5 MHz. Imaging range up to 10 m is possible in turbidity concentrations of suspended ocean sediment (average particle diameter from 1 to 10 μ) of several thousand parts per million. Expected ranges are at least five times larger in clear water. Fabrication and performance of the transducer array are discussed. Image scanning mirror, internal and external electronic circuitry, and the image display, all associated with the hydroacoustic converter, are also delineated.
An Infrared Window Assembly for Ultrahigh Vacuum Systems
Authors: Kottke Michael , Greenler Robert G.
Published: February 2004

A simple compact window assembly for ultrahigh vacuum systems is described which uses Irtran 2 or Irtran 6 ir transmitting optical material. The assembly is made in a standard ultrahigh vacuum flange using commercially available components. The window is sealed in place with silicone resin. After curing, the assembly can be repeatedly heat cycled up to 200°C without failure.
Apparatus for Studying the Behavior of Sliding Electrical Contacts at Very High Speeds
Authors: McElligott P. E.
Published: February 2004

A pin on disk machine is described which is used to study the friction, wear, and electrical behavior of sliding electrical contacts at speeds to 145 m/sec. Some typical results for an electrographite brush on medium carbon steel are presented.
A Generator for Nanosecond Charge Pulses
Authors: Firth J. M.
Published: February 2004

The circuit described delivers small current pulses from a high impedance source. The 20 nsec pulse enables the circuit to be used as a charge source, variable from 10−15 to >10−12 C/pulse, for testing charge sensitive amplifiers. Rates up to 107 pps are available. An external gate input enables pulse bursts to be obtained, and single shot operation is possible, either manually or remotely triggered. A simple calibration check can be used.
A Spark Gap Monitor
Authors: Brown David
Published: February 2004

A relatively simple method for determining the delay of many electrical signals with respect to a common trigger (e.g., in capacitor banks) is described. Using the well known principle of time-to-pulse-height conversion, a low leakage polystyrene capacitor is charged to a voltage proportional to the delay. A reed relay is used to disconnect the capacitor from the charging circuit, which permits the charge to be maintained on the capacitor for many seconds. Another reed relay is employed to connect each capacitor to an ADC when it is desired to digitize the charge on the capacitor. A change in delay of less than 1 nsec (with a full scale of 200 nsec) is reliably detected for many hundreds of signals at a parts cost of less than $10 per signal.
A Simplified Retarding Field Photoelectron and Auger Electron Spectrograph
Authors: Klein Wolfgang
Published: February 2004

Design and performance of a bakable, stainless steel, ultrahigh vacuum apparatus for Auger electron spectroscopy, photoelectron energy distribution, and work function measurements are described. It is easily built, can be attached as an accessory to any vacuum system with a 6.3 cm i.d. flange, and is especially useful for the investigation of photoemitters.
The Stability of Carbon Resistance Thermometers
Authors: Johnson W. L. , Anderson A. C.
Published: February 2004

The drift in resistance at a fixed temperature of a variety of carbon composition resistance thermometers has been measured in the temperature range 0.03–6 K. It is found that the drift in terms of an apparent ΔT/T is smaller for resistors having a smaller temperature sensitivity, and that these thermometers therefore have a better reproducibility in the usual meaning of the word. It is also shown that baking a resistor at temperatures of 300 to 400°C produces units essentially identical to unbaked resistors having the same room temperature resistance as the baked unit.
Correlation Measurements of the Response of Fast Photomultipliers in the Subnanosecond Region
Authors: Corti M. , Vendramini A.
Published: February 2004

We describe a method for measuring intensity correlations of light over times shorter than the resolving time of a photomultiplier. The method is based on sampling techniques and utilizes commercial electronics. The correlation times of photomultipliers are determined with an error smaller than 20 psec. The correlation characteristics of three fast photomultipliers, one C70045 and two XP1210, are measured for different anode voltages.
A Wavelength Insensitive Electron Diffraction System
Authors: Nee H. J. , Longini R. L.
Published: February 2004

A ring of diffracted electrons is focused onto an electron detector by an on-axis focusing electrode. In this way diffraction pattern data can be interpreted electrically and it is possible to obtain crystallographic data from crystal films while they are being deposited or while they are undergoing morphological changes. The system is insensitive to precise beam energy. In fact, for an on-axis spherical focusing electrode the determination of crystal structure is essentially independent of the wavelength of the incident electron radiation. We believe this to be a unique result. In practice it is necessary to use a compromise electrode because there is no possible way to support or to apply voltage to an isolated sphere.
New Methods for Derivation of Plasma Light Data from Television Apparatus
Authors: Rather John D. G. , Hayes Cecil H. , Nelson Christopher M.
Published: February 2004

We describe some novel uses of television for continuous monitoring and adjustment of a pulsed beam plasma experiment. Quantitative information can be obtained giving the position, size, and shape of the light emitting plasma. The absolute light intensity and the profile of the plasma can be separately obtained from a video scan analyzer. Time resolution of events occurring in a time span of ∼10 nsec can be achieved by incorporating a pulsed image intensifier ahead of the television camera tube. These techniques supplant photographic methods and augment information derivable from microwave and magnetic diagnostics. Some suggestions are made for future applications to other types of data analysis in physics and astronomy.
Measurement of Fluid Velocity Gradients Using Laser-Doppler Techniques
Authors: Goldstein R. J. , Adrian R. J.
Published: February 2004

Two methods are developed for the measurement of fluid velocity gradients using a laser-Doppler anemometer. In the first method the velocity gradient is found by a single measurement of the bandwidth of the laser-Doppler signal spectrum. In the second, velocity gradients very close to a wall are calculated from the amount the signal spectrum shifts in frequency for a small change in the position at which the spectrum is measured. Both methods are examined theoretically and experimentally.
A Digital Multichannel Photometer
Authors: Beaver Edward A. , McIlwain Carl E.
Published: February 2004

A semiconductor diode image tube system has been built which has the characteristics of a good photomultiplier tube but which can simultaneously measure light intensity at 38 different positions. Tube dark current is 0.02 count/sec/position. A tube with up to 1000 elements appears feasible.
vhf Pulsed Magnetic Resonance Duplexers
Authors: Moores B. Michael , Armstrong Robin L.
Published: February 2004

Coupling schemes for pulsed magnetic resonance spectrometers operating in the vhf region are discussed. Three such schemes are described in detail and their performances compared, using the 81Br nuclear quadrupole resonance signal at ∼200 MHz in polycrystalline K2PtBr6. The first scheme employs a hybrid T, coaxial ring circuit with the transmitter, receiver, sample coil, and a dummy load in the four arms. Series and shunt PIN diode switching elements form the basis of the second scheme proposed. Finally, a PIN diode bridge which combines the previous two schemes is described.
The Elimination of Second Order Aberrations in Uniform Field Wedge Magnets with Slightly Rotated Edges
Authors: Donnetti M. , Sanna G.
Published: February 2004

The coefficients of the first and second order optic transformation for the midplane of a uniform field wedge magnet having curved entrance and exit boundaries and rotated input and output faces have been first derived by Brown, Belbeoch, and Bounin [Rev. Sci. Instrum. 35, 481 (1961)]. Assuming such results and limiting the edge angles to be small (i.e., of the same order of magnitude as the input conditions of the trajectories) simplified analytical expressions can be derived for the above coefficients. Taking advantage of this achievement, it is possible to develop a general discussion concerning the possibility to eliminate the aberration terms. It is shown that for magnets with deflection angles within the interval (π,2π) a complete elimination of the second order terms in position (x) can be achieved. For magnets with deflection angles in the interval (0,π) it is only possible to nullify some pairs of such terms.
Magnetic Densimeter Using an rf Sensing Coil
Authors: Almeida S. P. , Crouch T. H.
Published: February 2004

Presented here is a description of a magnetic densimeter using an rf sensing coil. The coil is used to sense the position of a small buoy floating in a liquid whose density is to be determined. The instrument's electronics is completely composed of solid state components. The densimeter was tested by making a calibration run on a National Bureau of Standard's sucrose sample. It was found to be capable of making density measurements to better than 3 ppm.
Application of an Energy Selective Detector to the Sputtering Analysis of Solids
Authors: Summers A. J. , Freeman N. J. , Daly N. R.
Published: February 2004

An ion probe facility is described. A single stage magnetic mass spectrometer coupled to an energy selective ion detector has been used to analyze sputtered ions. Energy selective operation is demonstrated for the analysis of a stainless steel sample.
Superconducting Magnetic Spectrometer for Cosmic Ray Nuclei
Authors: Smith L. H. , Buffington A. , Wahlig M. A. , Dauber P.
Published: February 2004

This paper describes the design, calibration, and operation of a magnetic spectrometer for particle astronomy. The spectrometer consists of a superconducting magnet, optical spark chambers, scintillation detectors, and associated electronics. The instrument has been flown in a balloon gondola to 4.8 g/cm2 residual atmosphere, where it was used to analyze the charge and differential rigidity spectra of primary nuclei from 5 to 100 GeV/c.
Source for Negative Ions of Refractory Metal Oxides
Authors: Center R. E.
Published: February 2004

A source is described for the production of negative ions of tungsten and rhenium oxides. Total negative ion currents of 4×10−8 and 1.5×10−8 A were obtained for rhenium and tungsten oxides, respectively, the dominant ions being ReO3− and ReO4− or WO3−, (WO3)2−, and (WO3)3−. Both thermionic emission and hot cathode arc discharges were used as the ion source with the oxides being produced by direct oxidation of the heated cathode.
High Sensitivity Piezogravimetric Method for the Study of Physical Adsorption
Authors: Khan G. M.
Published: February 2004

The reliability and the scope of the piezogravimetric method using a 10 MHz AT-cut quartz crystal is described. The influence of side effects on the resonant frequency is analyzed and evaluated. The rugosity of the crystal surface, as determined from the adsorption isotherm of argon at −196°C is nearly 2, and the sensitivity of the crystal microbalance, with the requisite long-term stability, is 2.14×10−9 g · cm2 · Hz−1, showing a significant improvement over the values quoted in the literature. Isotherms for argon, n-hexane, and water vapor have been obtained, and compared with those determined by other workers.
Computer-Controlled Microscope for Automatic Scanning of Solid-State Nuclear Track Recorders
Authors: Cohn Charles E. , Gold Raymond
Published: February 2004

An optical microscope having computer control of specimen motion in three dimensions, via stepping motors, has been developed and used for automatic scanning of solid-state nuclear track recorders. Programming for this system includes provisions for detection and area measurement of individual tracks as well as automatic adjustment of focus.
Gain Variations in Channel Electron Multipliers
Authors: Bedo D. E.
Published: February 2004

Using measurements of pulse height distributions of four channel electron multipliers, the individual multiplier gains have been followed throughout an operating history of 2×1011 counts. These multipliers all exhibit an initial gain decrease occurring over the first 109 counts followed by a slight gain increase and stabilization at approximately 1010 counts. An intentional increase in anode voltage after an accumulated exposure of 2×1010 counts resulted in a gain increase which was reasonably maintained for the remainder of the testing period. Additional operational tests in which chemical additives were introduced into the vacuum environment have isolated at least one chemical (lauric acid) which appears to offer a technique for producing gain recovery in a degrading multiplier.
Pressure Cell with Ten Electrical Leads for Liquid Hydrostatic Pressures to 60 Kilobars
Authors: Zeto Robert J. , Hryckowian E. , Vanfleet H. B.
Published: February 2004

A cylindrical two-part stainless steel pressure cell with 10 electrical leads that exit directly from a 2.33 cm3 liquid working volume was designed for the generation of hydrostatic pressures to 60 kilobars in a liquid-solid hybrid system. The structural design, electrical lead system, high pressure liquid seals, and capability of the hydrostatic pressure system are described and discussed. The hydrostatic pressure cell has been used successfully for several years.
A Mechanical Device for Controlling the Radial Intensity Distribution of a Light Beam
Authors: Turner R. , van der Hoeven C. J.
Published: February 2004

A device is described which produces a beam of light which, time averaged, is axially symmetrical in intensity. Results are given which show that the intensity distribution can be controlled to within ½% of a desired symmetrical distribution.
Xenon Flash Lamp for EPR Kinetic Studies
Authors: Doetschman D. C.
Published: February 2004

A xenon flash lamp is described which delivers a 3.5 μsec light pulse (2.9×1016 quanta) to an EPR crystal sample. The pulse is directly transmitted through a fused silica light pipe from the discharge to the crystal. The method is a significant improvement upon the use of a flash tube with conventional optics.
A Simple, Effective Device for Supplying a Controlled Temperature Gas Stream
Authors: Jensen F. R. , Bushweller C. H. , Beck B. H.
Published: February 2004

A very simple but highly effective system for supplying a gas stream at a temperature variable from room temperature to the temperature of the heat exchanger bath is reported.
The Use of Platinum Black for Improved Electron Collection
Authors: Losee Jon R. , Burch David S.
Published: February 2004

The total secondary electron emission coefficient for platinum black on stainless steel is measured over a range of electron energies from 0 to 40 eV. Also, the electron reflection characteristics for an improved platinum blacked screened collector are reported.
A Fluorine Compatible Low Temperature Electrical Feedthrough
Authors: Straty G. C. , Younglove B. A.
Published: February 2004

A simple seal is described which has been used successfully to seal electrical leads into a cell containing liquid or gaseous fluorine.
Measurements of the Shielding Effectiveness of Coaxial and Two-Conductor Cables
Authors: De Lorenzo J. T.
Published: February 2004

A technique to measure the effectiveness of shields on coaxial and two-conductor cables was developed and applied to several different types. Such measurements require considerable skill, and the published literature does not describe methods adequately to make reliable measurements without extensive experimentation and, very likely, misleading results. This paper describes this measurement technique and gives results on several cables. The reliability of the measurement was verified by comparing calculated and measured results for a solid copper-sheathed coaxial cable.
Calibration of Small Gauge Thermocouples
Authors: Stewart W. F. , Edwards S. F.
Published: February 2004

A technique has been developed to dynamically calibrate fine wire thermocouples of 0.025 mm diam and smaller to 1625 K in less than 10 sec. In this method, the varying physical parameters present under typical dynamic heating conditions are simulated, and therefore, wire deterioration can be related to time, temperature, pressure, and atmosphere. A description of the equipment and procedures is given along with the preliminary results that correlate well with thermoelectric theory.
Analysis of Automatic Fission Track Scanning in Solid-State Nuclear Track Recorders
Authors: Gold Raymond , Cohn Charles E.
Published: February 2004

A computer controlled microscope has been developed for the automatic scanning of fission tracks in solid-state track recorders. Emphasis has been placed on the attainment of absolute accuracy comparable to that already demonstrated in manual track scanning. Analysis of automatic fission track data is considered in detail. It is demonstrated that track overlap or pileup can be accurately described within the framework of the paralyzable counter model. Absolute calibration of this system has been successfully carried out for Makrofol solid-state track recorders. Absolute fission rate measurements by automatic track scanning of Makrofol have been established with at least as high an accuracy as that of manual track scanning. Limitations due to effects of nonuniformity in fission track density have been estimated. Extension of these precise capabilities to mica solid-state track recorders has been attempted. In contrast with Makrofol, unresolved difficulties have been encountered in the automatic scanning of mica.
Energy Dispersed Neutral Beams
Authors: Barnett C. F. , Ray J. A.
Published: February 2004

Energy dispersed neutral hydrogen beams have been obtained by passing H+ or H2+ through an argon gas cell. The gas cell was composed of an 11-electrode ceramic structure across which a retarding potential was placed. Neutrals formed had an energy characteristic of the equipotential line on which the electron capture collision occurred. Flat energy distributions were obtained with linear retarding potentials.
A Semiautomatic Stripping Analysis Instrument
Authors: Megargle Robert
Published: February 2004

A stripping analysis instrument was designed and constructed using relays at key points to control the operation. Each relay can be operated manually with switches on the front panel or placed under the control of a digital control circuit. The control circuit takes the instrument sequentially through five modes. In the ready mode the operator fills the cell, sets the controls, and pushes start. The instrument goes into the electrodeposition mode for a preset time where the unknown is deposited on the electrode at constant potential in a stirred cell. This is followed automatically by a wait mode for another preset time, and then by a scan mode where the metals deposited in the electrodeposition mode are stripped off and measured. When the scan mode time is over, the instrument enters the completion mode where the final voltage is held for exhaustive stripping of the electrode. The instrument goes from the completion to the ready mode when the operator intervenes.
A Vertically Oriented Double-Crystal Attachment for Studying Molecular X-Ray Spectra
Authors: Whitehead H. C. , Layfield J. D. , Andermann G.
Published: February 2004

A vertically oriented double-crystal attachment was designed and constructed for use on a standard Norelco vacuum x-ray spectrograph. The attachment achieves the mechanical stability and performance of similar horizontal attachments. It yields usable intensities and resolutions of 1–2 eV, thus providing capabilities for studying molecular x-ray spectra.
A Furnace for High Field Mössbauer Experiments
Authors: Coey J. M. D. , Price D. C. , Morrish A. H.
Published: February 2004

A vacuum furnace for Mössbauer effect experiments is described which fits into the 5 cm room temperature bore of a superconducting solenoid. The temperature homogeneity of the absorber, a disk 2.0 cm in diameter, is better than 0.25°C at 360°C. As an illustration of its use, the complete temperature dependence of the hyperfine fields at the five iron sites of SrFe12O19 has been determined.
Rapid Readout from Dual Wavelength Spectrophotometers
Authors: Chance Britton , Graham Norman , Sorge John , Legallais Victor
Published: February 2004

Three methods are described for extending the time range of the dual wavelength spectrophotometric technique. First, a dual wavelength system employing interference filters (essentially a differential colorimeter) is described which employs no light modulation and thus gives operation down to the shortest time measurable in view of the system signal-to-noise (S/N) ratio. The second method employs dual wavelength light modulation and synchronizes the transient phenomena to the flash of the measuring light. While this method extends the time range down to that obtainable in view of S/N ratio of the optical system it is essentially a single beam method and does not compensate for optical artifacts that occur during a single flash of the measuring light. The third method extends the time range of the dual wavelength method by substituting for the vibrating mirror an air-turbine-driven mirror capable of rotating at several kilohertz and giving dual wavelength readout every 400 μsec or less. The three methods have been employed in time ranges of 40, 200, and 1000 μsec, respectively, in the measurement of the fast reaction of oxygen with cytochrome oxidase bound to mitochondrial membranes.
Reanalysis of the Trajectories of Electrons in 127° Cylindrical Spectrometers
Authors: Arnow M. , Jones D. R.
Published: February 2004

An approximate solution for electron trajectories in a cylindrical field is presented and discussed in connection with the 127° spectrometer originally proposed by Hughes and Rojansky. The approximate solution is compared to a numerical one, and is used to calculate the line shape in a few special cases.
Ultrasensitive Technique for Microwave Susceptibility Determination Down to 10−5
Authors: Patton Carl E. , Kohane Theodore
Published: February 2004

An ultrasensitive technique has been developed which allows the measurement of the microwave susceptibility components down to levels on the order of 10−5 on small spherical samples of ferrite materials. The novel feature is a feedback scheme to lock the signal klystron onto the 3 dB points of the high-Q cylindrical activity containing the sample. By beating the signal klystron against a crystal-oscillator-stabilized reference klystron, the frequency width of the cavity at half-power can be measured with an error less than a few hundred hertz, leading to the extremely high resolution. The most useful application of the technique to date is the study of microwave relaxation in the form of an effective linewidth several thousand oersteds away from ferromagnetic resonance.
Simultaneous Measurement of Attenuation and Velocity Change with an ltrasonic Continuous Wave Spectrometer
Authors: Hoffman A. R. , Purvis M. K.
Published: February 2004

A somewhat simplified version of the continuous wave ultrasonic spectrometer described by Leisure and Moss [Rev. Sci. Instrum. 40, 946 (1969)] has been used to simultaneously measure variations in both sound velocity and attenuation. The system has reproducibly measured velocity changes as small as a few parts in 108 and amplitude changes of a few parts in 104. Procedures for use of the cw system are discussed and results in two different metal samples are presented.
Residual Drag Torque on Magnetically Suspended Rotating Spheres
Authors: Fremerey J. K.
Published: February 2004

An almost quantitative explanation of the residual drag torque on freely spinning steel spheres in magnetic suspension is given by comparing previously published experimental data with theoretical results of Keith (1963). Accordingly, the residual drag torque is mainly caused by the earth's rotation. The associated decay ratio −ω̇/ω increases quite linearly with the rotor angular velocity ω. A distortion of the rotational symmetry of the supporting magnetic field enhances the decay ratio. This effect decreases with increasing rotor speed. The influences of rotor imperfections and of lateral rotor vibrations are also considered.
Simultaneous Measurements of Temperature and Velocity in Heated Flows
Authors: Chevray Rene , Tutu Narinder K.
Published: February 2004

Although measurements in nonisothermal flows have been made with constant current hot wire anemometers, the signals obtained are not amenable to linearization and do not permit continuous and simultaneous measurements of velocity and temperature. The instrument described here, consisting of two hot wire probes operated in different modes provides separate and simultaneous signals directly proportional to velocity and temperature for the frequency range of interest (0–10 kHz). This instrument was tested in a controlled environment and the results proved very satisfactory.
Laser Radar (LIDAR) for Mapping Aerosol Structure
Authors: Allen R. J. , Evans W. E.
Published: February 2004

This paper describes a third-generation experimental Q-switched, ruby laser radar or lidar useful for air pollution mapping and meteorological studies. This system differs from its predecessors in that it incorporates (1) automatic inverse-range-squared receiver gain compensation, (2) coaxial transmitter and receiver optics, (3) automatic scanning and pulsing at equal angle increments or time intervals for fixed operation, and at equal distances traveled for mobile operation, and (4) video disk storage and instant replay of scan sequences. Details of these improvements are included. Photographs of typical displays are also included to illustrate atmospheric returns recorded during range-height mapping of a smoke plume from an industrial plant, showing a cross section of the plume's structure; plan position mapping of the effluents from several industrial plants, indicating those emitting particulates; and distance-height mapping, showing differences in pollution and changes in the height of the inversion layer obtained while driving through a city.
Instrument Response Functions for Potential Modulation Differentiation
Authors: Houston J. E. , Park Robert L.
Published: February 2004

An exact method is outlined for handling the effect of amplitude on the results of potential modulation differentiation. The method involves the derivation of the response functions for the various spectral components corresponding to a unit impulse input. Actual analytical expressions are derived for these components corresponding to both cosine and square wave modulation functions. The formalism is demonstrated to be applicable to arbitrary input functions and of particular value in situations where signal-to-noise requirements forbid the use of small modulation amplitudes.
The Design and Construction of an Ultrastable Air-Bearing Turntable
Authors: Saunders K. D. , Beardsley R. C.
Published: February 2004

The design of an ultrastable but inexpensive air-supported turntable for rotating fluid dynamics experiments is presented. The rotational stability of this turntable is a few parts in 105, about an order of magnitude better than other turntables commonly in use.
Automatic Impedance Measurements Using Thermal Noise Analysis
Authors: Micheron F. , Godefroy L.
Published: February 2004

An apparatus permitting measurements of current and voltage thermal noise of two terminal devices has been built using a correlator amplifier and a controlled amplitude white noise generator. It allows accurate determinations of device impedance components, especially of nonlinear devices such as thin ferroelectric capacitors.
An Automatic Balanced-Filter Device Featuring Three Levels of Attenuation and an Automatically Operating Beam Stop with an Adjustable Range
Authors: Buscemi Mario
Published: February 2004

A compact balanced filter device for use with an automated x-ray diffractometer is described. Besides the balanced filters, the device also contains two automatically controllable attenuators providing three levels of attenuation. It also features an automatically operating beam stop which is not dependent upon the electrical system and adjusts to blank out the incident beam from 0° to ±6° two theta. Simplicity of design permits easy duplication.
Multichannel Photon Counter for Luminescence Decay Measurements
Authors: de Bye J. A. W. van der Does , van den Bosch A. C. P. , Hart C. M. , Saitoh M. , Slob A. , Verhoog P.
Published: February 2004

A photon counting 10 channel buffer memory enables the storage of periodically excited fast decays from weak luminescent sources in commercially obtainable multichannel analyzers, digital oscilloscopes, and other instruments with relatively slow memories. Integrated E2CL gate circuits serve as the building blocks and make a time resolution of about 10 nsec possible. Light emitting diodes were used to simulate exponential decays for the testing of the measuring system.
Switching Jitter in Spark Gap Triggered by a TEM00-Mode Mode-Locked Ruby Laser
Authors: Milam D. , Gallagher C. C. , Bradbury R. A. , Bliss E. S.
Published: February 2004

The first study of jitter in a laser triggered spark gap switched by pulse trains from a mode-locked ruby laser is described. The spark gap was fired by producing gas breakdown in a high pressure argon-nitrogen mixture between the pole pieces. Jitter was measured as a function of the position of the lens used to focus the laser beam and as a function of the ratio of the applied voltage to the self-breakdown voltage of the gap. Jitter values of less than 2 nsec were obtained under optimum conditions provided that the gap was fired by the early part of the pulse train.
An Electronic Correlator for Photoelectric Correlation Measurements
Authors: Chopra S. , Mandel L.
Published: February 2004

An instrument has been developed for determining intensity correlation functions of a light beam with high accuracy. It is based on digital storage of the arrival times of up to six photoelectric pulses following a start pulse. The times are stored in the memory of a multichannel analyzer, such that the histogram of arrival times is a direct measure of the form of the intensity correlation function. The correlator allows data to be accumulated at a much higher rate than in a time-to-amplitude converter.
A Method for Measuring the Spatial Dependence of the Index of Refraction with Double Exposure Holograms
Authors: Küpper F. P. , van Dijk C. A.
Published: February 2004

An extension of Luneburg's lens calculation to weakly refractive media offers the possibility of determining the spatial dependence of the index of refraction n if there exists a linear relation between (n−1)2 and r2. Experiments are described to prove the idea. The method provides a test for the radial dependence of the refractive index as well as (in the case of a suitable distribution) a measurement of the characteristic parameter that defines this dependence. The procedure is based on the detection of a change of the focal length of a system by double exposure interferometric holography. Focal lengths longer than 103 m can be detected. The application of the method to measure electron densities of plasmas is discussed.
An Adjustable Gas Inlet System for an Isotope Mass Spectrometer
Authors: Coleman M. L. , Gray J.
Published: February 2004

A versatile gas inlet system has been devised that overcomes many of the difficulties associated with other methods. A metering valve has been inserted between one of the two capillaries and the source of an isotope mass spectrometer. Tests have shown that the valve not only controls flow rate but also determines the proportion of molecular to viscous flow, in such a way that the fractionating effects of the inlet systems are equalized regardless of the differences between their reservoir pressures. Some of the advantages are ease of balancing capillaries (allowing the use of glass) and elimination of bellows or mercury pistons, allowing baking of the whole inlet system. The device may be automatically controlled for continuous balancing of flow rates.
A Precision Current Pulse Generator for NMR Self-Diffusion Measurements by the Pulsed Gradient Technique
Authors: Matson Gerald B.
Published: February 2004

An apparatus is described for delivering controlled pulses of current into an inductive load. Digital logic is utilized for control of the pulse duration, and current feedback is used to control the magnitude of the pulse. The apparatus was designed to enable NMR self-diffusion measurements to be obtained by the pulsed gradient technique, and diffusion results are shown for number 15 white mineral oil using pulse durations of 10 msec and magnitudes of over 25 A.
Application of Dual Parameter Analyzers in Solid-State Laser Tests
Authors: Schleusener Stuart A. , White Kenneth O.
Published: February 2004

New applications of a 128×128 channel, computer controlled, dual parameter analyzer used to record, compute, and display solid state laser emission and propagation data are described. The pulse height analysis coincidence mode is used to make spike amplitude measurements on reference and propagated signals or make spike coincidence measurements on two spectrometer output signals. An X-Y contour mode display provides a real time visual indication of results for wavelength dependent absorption tests, cavity mode tests, and beam cross section studies. A description of an operating system and initial test results are presented.
A Tubular Calorimeter for High Power Laser Pulses
Authors: Gunn Stuart R.
Published: February 2004

An isoperibol calorimeter employing a 72 junction thermopile and a massive metal jacket is described. The receiver consists of a nickel-plated copper tube; the beam enters at an angle of 45° and travels through the interior, undergoing multiple partial reflections. The aperture is 16 mm; the detection limit for small pulses is 1 mJ and the precision for large energies is 0.1%. Measurements have been made with 100 nsec, 500 mJ cm−2 pulses. The instrument has a number of advantages over cone calorimeters.
An Electrohydrodynamic Ion Source for the Mass Spectrometry of Liquids
Authors: Evans C. A. , Hendricks C. D.
Published: February 2004

An electrohydrodynamic ion source has been constructed and attached to a high resolution mass spectrometer. This ionization process is based on the interaction of a conducting liquid surface and an intense electrostatic field. An ion source operating on Ga–In eutectic alloy has produced in excess of 30 μA of ion current. The mass spectra obtained from the Ga–In source provided conclusive proof of the production of singly charged, monatomic ions. In addition the ion source ionized five impurities dissolved in the liquid eutectic.
Subnanosecond High Voltage Attenuator
Authors: Sutphin H. Dean
Published: February 2004

A high voltage attenuator has been developed and tested that is capable of maintaining pulse rise times of less than 300 psec. Pulse amplitudes to 5 kV may be attenuated by a factor of 16, allowing the use of high speed, lower voltage commercial attenuators for reduction of the pulses to oscilloscope levels. The mechanical and electrical design maintains an impedance of 50 Ω.
A Gasdynamic Method for Calibrating Volume Flowmeters
Authors: Winicur Daniel H. , Fraites James F.
Published: February 2004

A simple, inexpensive gasdynamic method is presented for calibrating volume flowmeters. The method requires no reference flowmeter and can be carried out in any system in which a gas flows through an orifice from a high-pressure source. Experimental results are presented which indicate that the accuracy of the gasdynamic calibration is about 3%.
Low Temperature Faraday Susceptibility Apparatus
Authors: Quinn Rod K. , Knauer Robert C.
Published: February 2004

A Faraday balance is described that permits highly accurate static magnetic susceptibility measurements to be made in the temperature range 2 to 300 K. Design features and measurement techniques are described that illustrate rapid sample processing and ease of operation.
An Automated Group Delay Measurement
Authors: Matsinger J. H.
Published: February 2004

An automated system to measure delay line group delay and transfer function phase as a function of frequency is presented. Measurements are made at fixed phase increments using a cw signal and a feedback system to stabilize the frequency source at each measurement point. Operation of the system is explained, block diagrams are presented, and potential errors are discussed in detail.
Film Deposition on Cylindrical Substrates by Asymmetric ac Sputtering
Authors: Mitsuoka Takeshi , Onodera Yutaka
Published: February 2004

The characteristics of film deposition by glow discharge sputtering on cylindrical substrates sitting on the anode surface are examined. In normal dc sputtering, the deposited mass is greater at the upper part of a substrate than at the lower part. But with asymmetric ac sputtering, it is found that the deposit distribution is more uniform, because sputtered particles arrive not only from the cathode but also from the anode. High quality Ta film resistors of tubular type are being produced with this technique.
An 11 Megawatt 6.8 Joule Flashlamp Pumped Coaxial Liquid Dye Laser
Authors: Bunkenburg J.
Published: February 2004

A coaxial flashlamp-pumped liquid dye laser is described having an output of 6.82 J with Rhodamine 6 G and 4.18 J with 7-diethylamino-4-methylcomarin. Outputs for treated and untreated dyes as well as geometries giving Gaussian and multimode output are compared.
High Trigger Current Structure for Double-Discharge TEA Lasers
Authors: Otis G.
Published: February 2004

The use of resistive plastic materials in the trigger circuit of double-discharge lasers has proven excellent in producing increased trigger current values, and in achieving successfull operation of lasers with large (up to 7.6 cm) electrode separations. Small signal gain values of 0.04 cm−1 have been obtained in a He:N2:CO2=50:20:30 gas mixture. Furthermore, the dielectric constant and resistivity of the plastic materials can be selected for pulse shaping in the trigger circuit. A trigger assembly has been designed in a simple and rugged unit, suitable for cascaded operation in long laser amplifier systems.
Scanning FM-CW Radar Sounder
Authors: Richter J. H. , Jensen D. R. , Phares M. L.
Published: February 2004

A second generation FM-CW radar sounder is described which has scanning capability and is fully mobile. The sounder is used as a remote sensor with unprecedented range resolution for fine scale structural details in the lower troposphere. Design considerations and performance characteristics of this new sounder are presented and examples of observations of clear air atmospheric scattering layers and structure of rain are given.
A Precise Low Temperature dc Ratio Transformer
Authors: Harvey I. K.
Published: February 2004

A prototype low temperature dc ratio transformer is described. This transformer, which uses a new technique for the precise equalization of current ratios, provides dc ratios which have accuracies of the order of 0.01 ppm and may be calibrated to 0.002 ppm. The ratio transformer may be applied in low temperature current and resistance ratio measurements of high accuracy and may, without modification, be used as a sensitive current detector.
Laser Driven High Power Pulsed X-Ray Tube
Authors: Passner A.
Published: February 2004

This paper describes an x-ray tube which delivers 10 A at 100 keV into a 1.5 mm diam spot in a 10−8 sec pulse at 500 pps using the photoelectric effect for the electron source.
Remotely Sensing Strain-Rate Meter Based on the Doppler Shift of Laser Light
Authors: Erdmann Joachim C. , Jahoda James A.
Published: February 2004

Laser light back-scattered in nonspecular directions from a rough specimen surface undergoing tensile deformation carries a Doppler shift. The device described employs two slightly separated light probes. The two scattered beams are mixed in a phototube with small aperture, approximately matched to the average speckle size. The strain-rate is proportional to the differential Doppler frequency. The accumulated strain is found by fringe counting.
An Adjustable Specimen Holder for X-Ray Texture Goniometers
Authors: Moment Roger L.
Published: February 2004

A specimen holder for use on a Siemens x-ray texture goniometer is described. It provides a reference surface against which the prepared specimen surface is pressed. It also allows for fine adjustment of the specimen position in and out of the diffraction circle. Use of the new holder results in increased intensity of the diffracted x rays.
A Segmented Faraday Cup to Measure kA/cm2 Electron Beam Distributions
Authors: Pellinen Donald
Published: February 2004

A segmented Faraday cup using 3.5 mm diam collectors has been used to measure electron beam current densities with incident power fluxes as high as 30 GW/cm2. The detector system has a rise time of 1–2 nsec.
Microsecond Duration Intense Relativistic Electron Beams
Authors: Friedman M. , Ury M.
Published: February 2004

A preliminary study was performed to ascertain the feasibility of delivering large quantities of electrical energy in relativistic electron beams of long pulse duration. An electron beam of 8 kA peak current and 250 kV peak voltage was produced with a duration of ≳1 μsec. The electron beam was transported through a 1 m long drift tube with little energy loss.
Improvement of the Translation Stage for the Transmission Topographic Goniometer
Authors: Middleton R. M. , Caslavsky J. L.
Published: February 2004

The Jarrell-Ash-Lang goniometer (manufactured by Picker X-Ray since 1970) is equipped with a Schneeberger stage to provide the accurate translational motion necessary for x-ray topographs. The commercial model produces striations on the topographs perpendicular to the scanning direction. These are caused by a torque exerted on the stage by the drive mechanism. This difficulty has been remedied by design changes.
Fast Ionization Gauge Studies of Quasisteady Gas Injection into Vacuum
Authors: Inutake Masaaki , Kuriki Kyoichi
Published: February 2004

Quasisteady gas injection into vacuum has been carried out by using a fast-acting valve of piston configuration. The pulsed motion of the piston was analyzed from stroboscopic photographs. There is no scatter in valve operation due to O-ring friction. The pulse width of the jet of several milliseconds and the mass flow rate during steady state can be varied independently. The rise time and the quasisteadiness of the pressure in the transient gas flow were measured by a newly developed fast ionization gauge of triode construction. The guage has a constant sensitivity from 3×10−3 to 2 Torr and a sufficient time resolution, and it introduces little obstruction of the gas flow. The pressure distribution measured in the jet expanding into vacuum agrees well with the rarefied gasdynamic prediction.
A Large Double Plasma Device for Plasma Beam and Wave Studies
Authors: Taylor R. J. , MacKenzie K. R. , Ikezi H.
Published: February 2004

The DP (or double plasma) device consists of two essentially collisionless plasmas that are separated from each other (for electrons only) by a negatively biased grid. Large cross section beams of ions are produced in one plasma by raising the potential of the other. Ion waves or shocks are produced in one plasma by oscillatory or large sudden (or ramp) potential changes in the other. Electrons emitted from two electrically separate spatial arrays of small filaments produce the two plasmas with densities in the range from below 108 to ∼1010 ion/cm3 with noise levels 〈δn/n〉≈5×10−4.
Ultrahigh Vacuum Quartz Spring Microbalance for Determination of Evaporation Rate and Vapor Pressure
Authors: Gardos Michael N.
Published: February 2004

An ultrahigh vacuum quartz spring mass sorption microbalance was designed and fabricated to measure the evaporation rates of low volatility substances, e.g., lubricants considered for space applications. The balance is accurate to ±7.2×10−4 g. Optimum test temperatures range from room ambient to 120°C. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. The observed vapor pressures of pure organic compounds were found to agree closely with those calculated and extrapolated according to applicable temperature-vapor-pressure relationships. Typical data are given on the evaluation of a conventional lubricating oil considered for space application.