bluuebunny/crossref_metadata_2025 huggingface dataset:
Airborne nondispersive infrared monitor for atmospheric trace gases
Authors: Sebacher Daniel I.
Published: March 2003

An airborne gas-filter correlation analyzer was designed and assembled to monitor atmospheric trace gases. Flight tests indicated that a methane version of this nondispersive infrared instrument performed properly while measuring CH4 concentration profiles as small as 1 ppm from altitudes of 0.15 up to 1.2 km. A unique multiple chopping scheme was developed to simplify the gas-filter technique and to provide an easy mechanical nulling procedure. The single-beam rotating-cell optical system integrated with a multipass sampling cell and the signal processing circuit are described in detail.
New method for measuring the thermal conductivity
Authors: Goldratt E. , Greenfield A. J.
Published: March 2003

A new experimental method is presented for measuring the thermal conductivity as a function of temperature. The basic innovation lies in extracting from the measured temperature profile of a sample in vacuo, the thermal conductivity of each individual cross-sectional sample element. The estimated experimental error is ±1%. Not only is high accuracy achieved, but also a self-checking procedure offers the possibility of avoiding systematic errors. Measurements on two samples of type 304 stainless steel are presented. Three independent sets of measurements give consistent values for the thermal conductivity to well within the estimated error of ±1%.
Ultrahigh vacuum low- and high-temperature silicon–glass cell for thermal infrared and intense CO2 laser pulses
Authors: Heidberg J. , Hussla I. , Hoefs E. , Stein H. , Nestmann A.
Published: March 2003

A durable flame sealed silicon glass infrared cell for use at ultrahigh vacuum (≲4×10−8 Pa) and temperatures between 77 and 600 K is described. The cell is suitable for thermal infrared as well as MW/cm2 CO2 laser pulses of 1 J energy. It can be fused directly onto a glass to stainless steel seal on a standard Conflat flange, thus making a variable temperature metal seal onto a metal UHV system. The integral leak rate and the ir transmission of the cell were measured. Infrared chemical applications are described.
Mutual inductance bridge for low-temperature thermometry and susceptibility measurements
Authors: Whitmore S. C. , Ryan S. R. , Sanders T. M.
Published: March 2003

We describe a solid-state mutual inductance bridge suitable for low-temperature thermometry and susceptibility measurements. The design features an electronically simulated variable mutual inductance. Particular care is taken to reduce spurious capacitive effects. The bridge is highly stable and linear. It has a resolution of 10−4 over the range 15 μH to 150 mH, and a noise limited sensitivity of 55 Ip−1 nH with a l-s time constant, where Ip is the rms primary current in mA. Application to thermometry is discussed.
Inductive impedance transducer for recording displacements of ferromagnetic and nonferromagnetic conductive objects
Authors: Kaplan B. Z. , Mishal R. , Fetman A. , Gressel C.
Published: March 2003

The paper describes an inductive magnetic transducer for on-line recording of translations and vibrations. The transducer consists of an iron cored sensor coil and simple accompanying circuitry. The main features which are peculiar to the present transducer are (a) facility for linearizing the voltage versus displacement characteristic for certain regions of distances, (b) ability to measure vibrations and translations of both ferromagnetic objects and nonferromagnetic conductive objects, (c) relative simplicity of circuitry, and (d) the fact that only passive components are used for the transducer and an output voltage enhancement is attained by the employment of resonance. The paper is introduced by a comprehensive review of various types of magnetic transducers.
Force measurement using an inductively coupled sensor
Authors: Ashworth H. A. , Milch J. R.
Published: March 2003

A low-compliance, high-bandwidth force sensor is described. The bending of a quartz plate is converted to an analog voltage by using a phase-locked loop to measure the change in frequency of two oscillators inductively coupled to the plate. The resolution of the sensor is approximately 10−5 N, with a bandwidth of approximately 1 kHz.
Method for sealing nylon chambers for use at low temperatures
Authors: Bischoff G. C. , Matthews J.
Published: March 2003

Two methods are described which were found to seal nylon to nylon for use at low temperatures.
Shock tube for simulating nuclear blast durations
Authors: Andersen W. H. , Louie N. A.
Published: March 2003

The general design of a shock tube that was fabricated and used to produce a shock pulse having a relatively long duration (comparable to that produced by a nuclear detonation) is described. This shock tube used the reflected portion of the wave to produce the peak and early history wave pressure acting on the target, and nozzle flow through the rear of the driver tube to control the remainder of the decaying pressure pulse profile. The estimated pressure profile is compared with the profile obtained by a transducer that was located just above the target surface, and they are in general agreement. The general performance of the shock tube is discussed and suggestions made for further improvement of the technique.
Piezodriven 50-μm range stage with subnanometer resolution
Authors: Scire Fredric E. , Teague E. Clayton
Published: March 2003

A micropositioning stage has been developed for use with optical and electron microscopes in the accurate measurement of fine lines used by the microelectronics industry and microscopic objects such as biological cells, air pollution particles, and asbestos fibers. The stage combines a piezoelectric driving element and flexure pivoted lever arms to achieve a compact, vacuum compatible device with a resolution of 0.001 μm or less over a range of 50 μm.
Pressure-jump apparatus suitable for repetitive experiments
Authors: Yasunaga Tatsuya , Tatsumoto Nobuhide , Harada Shoji , Hiraishi Michinori
Published: March 2003

A repetitive pressure-jump apparatus has been devised and used for the measurement of a small relaxation effect in solution. Although the pressure rise time of the apparatus is inferior to the usual method, signal averaging has enhanced signal-to-noise ratio of the relaxation spectrum.
Shadowing technique for reducing charge buildup in scanning Auger microanalysis
Authors: Shaffner T. J.
Published: March 2003

Charge buildup on insulating specimens examined by the scanning Auger microprobe cannot be controlled by conventional surface metal coating techniques which hide the signal of interest. Instead, a simple TEM grid of appropriate geometry can be used as a mask during deposition to leave untouched select spots for analysis.
Parts-per-million water vapor generating system used to simulate moisture in small integrated circuit packages
Authors: Hartley Johnny L.
Published: March 2003

A simple, portable system has been developed and tested for generating a known water–vapor content is selected permanent gases or gas mixtures. Parts-per-million values ranging from 250 to 20 000 are generated in a continuous flowing stream at flowrates ranging from 50 to 200 cm3/min. A known volume of the flowing gas can be selected to simulate the internal free volume and internal pressure of hermetically sealed packages as small as 0.04 cm3. By using a variety of available connectors, the selected volume of gas may be transferred into the inlet system of a mass spectrometer for water–vapor calibration. Generator stabilizing time and upper flowrate limits are given along with test results when compared to a Transfer Humidity Standard.
Electronic micropositioning with ferroelastic–ferroelectrics
Authors: Lemons R. A. , Coldren L. A.
Published: March 2003

The change in crystal shape which accompanies domain wall motion in a coupled ferroelastic–ferroelectric crystal such as β-gadolinium molybdate can be utilized for precise micropositioning under electronic control. The displacement available from such a crystal is 10 to 100 times greater than a piezoelectric element of similar dimensions can provide.
Mass/thickness detector employing inexpensive integrated circuits
Authors: Ashworth H. A. , Shacklette L. W.
Published: March 2003

Modern integrated circuits have made possible the construction of a simple and inexpensive quartz crystal mass/thickness monitor having high sensitivity and good resolution. We have constructed such a thickness monitor having a resolution of 0.1 nm for evaporated lead films. This same device can also be readily made to function as a microbalance capable of resolving mass changes as small as 1 ng.
X-ray reflectometer for optical efficiency and scatter measurements
Authors: Reynolds J. M. , Fields S. A. , Holland R. L.
Published: March 2003

An instrument has been developed to determine the reflection efficiency and scatter characteristics of optical samples at x-ray wavelengths from 1.5 to 113 Å. The reflectometer operates in an oil-free vacuum chamber and measures the reflection efficiency and scatter characteristics as a function of the angle of incidence. The reflection efficiency is given for λ=8.34 Å incident on a fused silica sample finished to a flatness of λ/10. The experimental reflection efficiency is compared to the theoretical data. The scatter curves are given for the direct x-ray beam and for the beam reflected from the fused silica sample at ϑ=50 arc minutes. The full-width-at-half-maximum (FWHM) resolution of the instrument is approximately 13 arc seconds as determined by a least-squares smoothing of the experimental data.
Continuous radon concentration monitoring
Authors: Cathey LeConte
Published: March 2003

The use of ionization chambers to continuously monitor the concentration of radon dissolved in ground water is described. In one case, air is bubbled through the water sample to strip the radon into the chamber. In a second operating mode, the sample water itself is flowed through the chamber. Support electronics systems are described for remote and urban applications.
Simple cell for the measurement of the radio frequency electrical properties of earth materials
Authors: Chute F. S. , Cervenan M. R. , Vermeulen F. E.
Published: March 2003

The design of a simple cell for determining the radio frequency electrical properties of earth materials is described. Basically, the cell consists of a coaxial sample holder fitted with electric and magnetic field probes. When excited as a section of transmission line the induced probe voltages are related in a straightforward manner to the electrical properties of the sample. The device is intended for use with a vector voltmeter which permits the direct and simultaneous measurement of the relative amplitudes and phases of these probe voltages. The cell permits the accurate and rapid determination of the conductivity and dielectric constant of earth materials over the frequency range 1 MHz–1 GHz, without the tedious and time consuming procedures associated with the bridge and slotted line techniques commonly used in this frequency range.
Modified apparatus for low temperature/high pressure Mössbauer absorber studies
Authors: Liu C. M. , Ingalls R.
Published: March 2003

A method is described in which a system designed to study Mössbauer sources as a function of pressure and temperature is modified to include absorbers as well. This is accomplished by coupling the Mössbauer source, mounted inside a cryostat, to an external transducer by means of a bellows. In addition, a simple modification has converted an existing helium Dewar to a dynamic gas flow cryostat. Temperature can be continuously varied from 300 to 20 K at pressures up to 200 kilobars.
Temperature-compensated induction extensometer
Authors: Yazdi A. R. , Deeds W. E. , Dodd C. V.
Published: March 2003

A linear displacement transducer, or extensometer, has been designed and constructed to measure displacements over a range of 0–150 mm. The transducer works by electromagnetic induction and consists of a bifilar coil coaxial with two conducting cylinders, one inside and the other outside the coil. The induction extensometer has been designed to eliminate errors caused by temperature changes from 0° to 1000°C. Experimental measurements show an error of 1 mm over the 150-mm displacement range for a temperature change of 500°C, and the error should not be larger over the full 1000°C temperature range. The displacement range can be varied from 2.5 to 250 mm by scaling the entire experiment up or down, and the temperature compensation can be made for any temperature range that is compatible with the constructional materials.
Microprocessor assisted real-time harmonic analysis by minicomputer
Authors: Matheson T. G. , Higgins R. J.
Published: March 2003

A real-time signal averaging and harmonic analysis technique for low audio frequency waveforms is described that, although based on based on earlier software emulations of lock-in detection instruments, eliminates problems inherent in the earlier systems. Parallel processing is employed between a data acquisition minicomputer (HP-2116B) and a microcomputer (Z-80) to (1) replace an earlier chopper-type lock-in algorithm with a coherent Fourier transform, (2) digitally produce a pure (0.01% THD) modulation sine wave, (3) simplify system tune-up, and (4) produce a high-quality, flicker-free, real-time display of the averaged waveform and its harmonic content.
Electrical noise measurements using a microprocessor-based system
Authors: Pender L. F. , Wintle H. J.
Published: March 2003

A microprocessor-based system for measuring low-frequency (less than 100 Hz) electrical noise power spectra is described. The main function of the microprocessor was to determine the noise autocorrelation function using simple ’’one bit’’ autocorrelation arithmetic, subsequent Fourier transformation to find the power spectra being done on a larger computer. Given that such larger computing facilities already exist, this system is much less expensive than more conventional analogue techniques. We illustrate the way in which this system was implemented to measure current noise in insulating polymers.
Compact sensitive instrument for direct ultrasonic visualization of defects
Authors: Bar-Cohen Y. , Ben-Joseph B. , Harnik E.
Published: March 2003

A simple ultrasonic imaging cell based on the confocal combination of a plano-concave lens and a concave spherical mirror is described. When used in conjuction with a stroboscopic schlieren visualization system, it has the main attributes of a practical nondestructive testing instrument: it is compact, relatively inexpensive, and simple to operate; its sensitivity is fair, resolution and fidelity are good; it has a fairly large field of view and a test piece can be readily scanned. The scope of its applicability is described and discussed.
Circuitry for the contactless detection of superconducting transitions
Authors: Gualtieri Devlin M.
Published: March 2003

Complete circuitry is presented for the detection of the superconducting transition in powders, or specimens for which the standard four-point resistance measurement cannot be performed. Specimens are placed within an inductance coil, and the change in the coil reactance is monitored as a function of temperature. The sensitivity is sufficient to detect the superconducting transition in 10−3 cm3 of lead, and only four integrated circuit packages are required.
Instrument for measuring the switching transition in ferroelectric thin films
Authors: Surowiak Zygmunt , Dec Jan
Published: March 2003

A description is given of the construction and operating principles of an instrument for investigation of the process of polarization reversing in ferroelectric thin films in an electric field arising from rectangular impulses. The system constructed enables investigation of changes of polarization as a function of intensity of electric field in a wide range of time intervals by means of an integrating system, and investigation of the time-course of polarization reversing as a function of intensity of electric field by means of a differentiating system.
Internal calibration to absolute values in flowthrough particle size analysis
Authors: Eisert W. G. , Nezel M.
Published: March 2003

Using a double-beam technique, a laser flowthrough microphotometer is described that allows internal calibrated size measurements of particles and suspension without the need of reference measurements. Nonspherical particles are oriented in a single file and their longest axes are measured by light absorption analysis. Additional information may be derived from light scattering. The size range is limited only by the flow system, and spans from 2 to 300 μm within a single measurement at the present design. Particle and cell analysis can exceed the rate of 100 000/s. Latex microspheres were analyzed and the data compared to that from microscopic examination. An example of the cell classification obtainable is given for stored human blood.
Low-dissipation tunable rf preamplifier for low temperature NMR applications
Authors: Wampach H. R. , Sullivan N. S.
Published: March 2003

We describe a simple circuit which can be used as an impedance matching device to improve the S/N ratio when lossy cables must be used in low-temperature NMR experiments. The total dissipation is less than 2 mW and the circuit operates satisfactorily down to 1.5 K. The only tuned circuit is the nuclear resonance circuit which incorporates GaAs (P) diodes which can be tuned remotely.
Coupled Marx–Tesla circuit for production of intense relativistic electron beams
Authors: Luches A. , Perrone A.
Published: March 2003

A two-stage Marx circuit was built and is used to multiply the input energy of our Tesla resonant transformer accelerator without missing resonance conditions. The present output characteristics of our coupled Marx–Tesla circuit are compared to those of the previous Tesla transformer. With the same input voltage and cathode to anode distance, we succeeded in doubling output voltage and current of the beam.
Description and characteristics of a wide-band linear circuit for pulse amplification
Authors: Kopp M. K.
Published: March 2003

A wide-band, linear, pulse amplifier stage was designed and tested. The closed-loop gain is ∼10, the gain-bandwidth product is 350 MHz, and the integral nonlinearity is <0.05%.
Vacuum interlock system for molecular beam epitaxy
Authors: Robinson J. W. , Ilegems M.
Published: March 2003

A vacuum interlock system which permits rapid loading of substrates for molecular beam epitaxy crystal growth is described. Substrates are introduced through a separate, independently pumped, loading chamber while maintaining the main growth chamber under vacuum, thereby minimizing contamination of the evaporation sources and reducing the downtime of the system between successive growth runs. The design permits outgassing of the substrates prior to their insertion in the growth chamber, and has provisions for a later addition of a separate sputtering or chemical etching capability.
Emission current regulator for ion cyclotron resonance spectrometers using an optical coupler. II
Authors: Amano C. , Inoue M.
Published: March 2003

An emission current control circuit for ion cyclotron resonance spectrometers has been constructed which maintains a constant beam current in the range 10−11–10−6 A with pulsed grid modulation. It regulates emission currents by automatically adjusting grid bias voltages with reference to a feedback signal. A solid state optical coupler is employed to transmit the feedback signal to a grid biasing circuit having a floating common voltage to accelerate electrons. Control to better than 0.1%/h is possible at any emission current between 10−10 and 10−6 A, and control to 0.3%/h at 10−11 A.
Cryostat for enzymology in the subzero temperature range
Authors: Churg Antonie K. , Gibson George , Makinen Marvin W.
Published: March 2003

An air-bath cryostat and sample stirrer for kinetic studies of enzyme reactions at subzero temperatures are described. The apparatus is designed to permit monitoring of the reactions using a commerical spectrophotometer. The sample temperature and mixing conditions are well defined and accurately controlled.
Practical thermometry with a thermographic camera—calibration, transmittance, and emittance measurements
Authors: Cetas T. C.
Published: March 2003

Methods of obtaining quantitative thermometric data with a thermographic camera are discussed. These include the assessment of errors associated with the camera itself and techniques for calibrating the particular camera. Difficulties arising from the nature of the object to be measured also are considered. These include determining the ’’penetration of depth’’ of infrared radiation emitted by the object (how ’’thick’’ is the surface?), measuring the transmittance of ’’windows’’ in front of th objects, and measuring the object’s emittance under somewhat adverse circumstances. Finally, an example of a temperature measurement is given. Practical considerations of theromometry are emphasized as opposed to radiometric measurements (such as spectral properties). Examples are drawn from measurements involving tissue-equivalent electromagnetic phantom materials.
Precision absolute measurements of strong and highly inhomogeneous magnetic fields
Authors: Honig A. , Moroz M.
Published: March 2003

The low-temperature (⪝4 K) dependence of the photoconductance in n-type silicon on the conduction electron and bound donor electron spin state serves as the basis of a high-precision, wide-range magnetic field measuring probe, which by virtue of its very small dimensions is well suited for spatial mapping of highly inhomogeneous fields produced by superconducting magnets. The probe may also be adapted to power and frequency measurement of microwave sources operating at ∼mW power levels and frequencies up to ∼500 GHz.
Multicell spinning drop interfacial tensiometer
Authors: Fink Thomas R. , Hearn Daniel P.
Published: March 2003

The design and performance characteristics of a thermostated multicell spinning drop interfacial tensiometer are described. The instrument features simple and reliable commercial components, ±1°C thermostating, reduced operational vibration, cells designed to reduce problems associated with gyrostatic equilibrium, and the capability to measure interfacial tensions between six pairs of liquids simultaneously.
Drive characteristics of a fast movable limiter in the JT-60 tokamak
Authors: Takashima T. , Ohta M. , Shimizu M.
Published: March 2003

A pair of fast-acting movable limiters are to be installed in the vacuum chamber of the JT-60 tokamak being designed at JAERI. Their purpose is to suppress skin current in the plasma column. They should travel across the vacuum chamber over a stroke of about 1 m in 0.1 s during the build-up phase of the plasma current. Each movable limiter system consists of the drive system, a vacuum seal, a bearing usuable at high temperature in a vacuum, and a molybdenum rail limiter head. For the drive a hydraulic mechanism is used with servovalves to control the oil flow. To develop satisfactory movable limiters for JT-60, the full-scale model was constructed and tested. Overall tests with the model showed high reliability, reproducibility, controllability, and safety of the movable limiter. The drive pattern measured is in good agreement with that simulated. The movable limiters should prevent the skin effect of plasma current in the current rising phase and also provide information on particle diffusion during the flat-top phase of plasma current.
Preparation of ultrathin polyethylene foils by film casting
Authors: Cranfill Betty
Published: March 2003

A procedure for making normal and deuterated polyethylene foils with a thickness of 0.02 to 2 μm by the film casting method is described. The thickness of the foils is controlled by the concentration and temperature of the solution, and the quality is determined by the uniformity of temperature and rate of solution drainage.
Control of temporal and spectral jitter in single mode pulsed ND:YAG oscillators
Authors: Owyoung Adelbert , Jones Eric D.
Published: March 2003

We report reliable operation of a repetitively pulsed (3 pps) passively Q-switched Nd:YAG oscillator on a single longitudinal mode with a high degree of temporal and spectral stability. The total output is 3.5 mJ in a 7-ns bandwidth limited pulse with diffraction limited divergence of 0.33 mrad.
Two simple freeze drying microscope stages
Authors: Flink James M. , Gejl-Hansen Frederik
Published: March 2003

In many instances it is advantageous to make real-time observations of freeze drying phenomena on a microscopic level. Two simple vacuum freeze drying chambers, suitable for use with the optical microscope at higher magnifications (600×), are described and examples of their use are noted.
New evaporation geometry for deposition of silicon monoxide film
Authors: Singh Awatar
Published: March 2003

A new evaporation geometry for the deposition of pinhole-free films of silicon monoxide has been developed. This geometry makes use of the fact that if silicon monoxide is heated in a chamber connected to a long narrow baffle perpendicular to it and leading to another chamber with a V-shaped opening, the paths for particle ejection are eliminated and homogeneous and pinhole-free film deposition occurs. The use of this geometry leads to reproducible films on a high yield basis. The same principle can also be used in other applications requiring the filtering of vapors. The geometry is found to be compatible with other materials which do not react with it.
Miniature drag sphere velocity probe
Authors: Donelan M. A. , Motycka J.
Published: March 2003

The development and testing of a miniature drag sphere velocity probe is described. Impetus for its development arose from a need to investigate the flow structure and turbulence beneath breaking surface water waves, i.e., a requirement for a fast-response small velocity probe which is useable in oscillatory flows. However, the presence of both drag (velocity) and inertial (acceleration) forces limits the measurable fluctuations to those having scales at least an order of magnitude larger than the sphere diameter, while the sphere diameter is itself limited by the requirement that the drag coefficient be independent of velocity. The resulting probe, with a sphere diameter of 0.43 cm, while not free of temperature drifts, pressure sensitivity, and cross-channel talk, yields encouraging results.
Demountable 3He melting curve thermometer
Authors: Corruccini L. R. , Mountfield K. R. , Sprenger W. O.
Published: March 2003

We describe a demountable 3He melting curve thermometer, suitable for use at low temperatures with liquid helium samples at any pressure. The thermometer’s resolution is 10 μK below 0.l K. It is designed to be particularly useful for experiments performed in magnetic fields.
Novel interferometer for the measurement of plasma density
Authors: Jacobson A. R. , Call D. L.
Published: March 2003

This report describes an interferometer recently developed and tested in prototype form. The device combines certain features of predecessor interometers but in a module which, subject to limitations on path-length and bandwidth, is simpler to use.
Improvement of the reflecting properties of electroformed metal grids by polishing
Authors: Rousseau B. , Setton R.
Published: March 2003

A technique is described which considerably improves the reflecting properties of ultrathin metal grids used as optical beamsplitters.
System for ESR measurements at hydrostatic pressures to 60 kilobars
Authors: Barnett J. Dean , Tyagi Som D. , Nelson H. Mark
Published: March 2003

A single-crystal sapphire serves both as a solid microwave cavity (X band) and an anvil in a Bridgman-anvil pressure geometry. A metal gasket is used in a manner similar to its use in the diamond-anvil pressure cell, and single-crystal samples are subject to purely hydrostatic pressures. The ruby-fluorescence pressure–measurement technique is utilized. Sample size is limited to a disk approximately 0.6 mm in diameter and 0.1 mm thick. ESR data on Cr3+ in ruby to 60 kilobars are given as an illustration of the precision and data quality. Line widths and profiles, as well as line positions, are meaningful. Very little degradation of the data is experienced at the higher pressures. The first and second derivatives of the zero-field splitting (δ) of the states in ruby with pressure are measured as dδ/dP= (6.70±0.08) ×10−4 cm−1 kilobar−1 and d2δ/dP2= (−2.44±0.30) ×10−6 cm−1 kilobar−2 at P=0. The gyromagnetic ratio g11 is shown to experience a fractional change less than 2×10−4 to 60 kilobars.
90-kilobar diamond-anvil high-pressure cell for use on an automatic diffractometer
Authors: Schiferl D. , Jamieson J. C. , Lenko J. E.
Published: March 2003

A gasketed diamond-anvil high-pressure cell is described which can be used on a four-circle automatic diffractometer to collect x-ray intensity data from single-crystal samples subjected to truly hydrostatic pressures of over 90 kilobars. The force generating system exerts only forces normal to the diamond faces to obtain maximum reliability. A unique design allows exceptionally large open areas for maximum x-ray access and is particularly well suited for highly absorbing materials, as the x rays are not transmitted through the sample. Studies on ruby show that high-pressure crystal structure determinations may be done rapidly, reliably, and routinely with this system.
’’Crystal bridge’’ for measuring the equivalent electrical parameters of piezoelectric crystals
Authors: Ramadan B. , Kos J. F.
Published: March 2003

The methods and instrumentation for carrying out precise measurements of the equivalent electrical parameters of piezoelectric crystals have been developed. An accuracy exceeding 0.05% has been achieved with low power dissipation in the crystal permitting the use of this system at low temperatures and particularly in applications concerning the detection of gravitational radiation.
High-pressure EPR cavity
Authors: Jaworski M. , Checiński K. , Bujnowski W. , Porowski S.
Published: March 2003

A high-pressure resonant cavity for sensitive EPR measurements is described. The cavity operating in the TE115 cylindrical mode enables EPR experiments to be carried out in the 77–300 K temperature range at high hydrostatic pressure up to 8 kilobar.
Simple analog correlator
Authors: Guharay S. K. , Saha S. K. , Sen Gupta S. N. , Mukherjee S. K.
Published: March 2003

An analog correlator has been constructed using a delay unit which is realized by simulation of the sixth-order Padé approximated result of exp(−jωτ) where j=√−1, ω the angular frequency of the signals of concern, and τ the delay in seconds. Several sinusoidal signals and a noise spectrum have been autocorrelated with this correlator; also, it has been applied to determine the impulse response of an RC low-pass filter. Results are in good agreement with theoretical predictions. This correlator has been used to study low- frequency signals in the region 1–50 kHz.
Novel electrode adaptation for N2 lasers
Authors: Fisher Amnon , Peacock Jon , Lee Edward K. C.
Published: March 2003

A novel electrode design is described and its performance is indicated.
Moving coil linear variable differential transformer
Authors: Ellis J. F. , Walstrom P. L.
Published: March 2003

A moving-coil linear variable differential transformer with no ferromagnetic components is described. The device is essentially interchangeable with a conventional moving-core linear variable differential transformer, but is virtually unaffected by ambient magnetic fields up to 8 T. The transducer is connected to a standard commercially available carrier amplifier for signal conditioning.
Op-amp mutual inductance bridge
Authors: Dundon Jeffrey M. , Kretschmar Mark E.
Published: March 2003

A mutual inductance bridge constructed from operational amplifiers is described.
Absolute calorimeter for measuring low-energy outputs from CO2 lasers
Authors: Jurela Z. , Jokić T.
Published: March 2003

This paper describes the construction of a calibrated energy measuring device for pulsed CO2 lasers of low output energy. An aluminium disk of low thermal capacity has been used for the detection of laser radiation. An Al2O3 layer has been electrolytically deposited on the aluminium disks. It is used as a highly absorbing surface (≳95% for wavelengths between 8.5 and 11.0 μm), thus eliminating the need for calibration. The laser output energy is calculated from the measured increase of temperature of a calorimeter disk of known thermal capacity. Calculations and measurements have shown that this device is capable of measuring the energy of a single pulse of the order of 1 mJ, and in a set of 10 pulses even to 0.1 mJ, for pulses as short as 1 psec.
Multichannel (e,2e) apparatus
Authors: Moore John H. , Coplan Michael A. , Skillman Thomas L. , Brooks Eugene D.
Published: March 2003

We describe an apparatus for the coincident observation of both outgoing electrons in an electron impact ionization, or (e,2e), experiment. The device employs ten detectors arranged such that every pair corresponds to a different set of momenta for the outgoing electrons intercepted by that pair. By simultaneously monitoring the output from all ten detectors it is possible to perform 25 simultaneous (e,2e) experiments. The results of these experiments can be compared without considering temporal variations of source conditions.
Multiple species ion energy analyzer applied to laser-induced plasma experiments
Authors: Hahn Sangkoo F. , van Hulsteyn David B. , Becker Michael F.
Published: March 2003

We have developed a device which employs parallel dc electric and magnetic fields in combination with an array of collectors and accompanying electronic circuits to measure simultaneously the momentum distributions of different ion species from a laser produced plasma. This diagnostic system automatically separates the ion species according to mass to charge ratio and utilizes the cyclotron motion to provide the momentum separation. The principle of operation, design configuration, and circuitry for the system are presented along with representative data obtained from a series of laser-induced plasma experiments.
Accurate Josephson junction analog
Authors: Magerlein J. H.
Published: March 2003

An accurate and simple electronic analog of a Josephson junction has been constructed and found useful in studying junction behavior in many circuits. The junction voltage is integrated using appropriate resetting circuitry to calculate the phase φ, and a current proportional to sinφ is generated. A simple nonlinear network for modeling the quasiparticle conductance is also described.
Anomalous gain changes in photomultiplier tubes for use in scintillation counting
Authors: Yamashita Mikio
Published: March 2003

Abrupt pulse height changes and different steady state pulse heights exhibited at particular count rates are observed reproducibly in RCA 8850 and 8575 tubes. These phenomena are shown to be identical in nature with the hysteresis effect observed previously in a different type of tube. The implications for a standard count rate stability test and precision scintillation counting experiments are briefly discussed.
Gas discharge ion source. I. Duoplasmatron
Authors: Bacon F. M.
Published: March 2003

The effects of the plasma expansion cup on the operation of a duoplasmatron ion source have been investigated by measuring the total ion current and the distributions of the ion energy, mass, and current density. A copper expansion cup did not affect the magnetic field near the anode of the ion source and consequently the ion current density distribution was sharply peaked near the center of the cup. Ion energy distributions were approximately symmetrical about anode potential. The dominant ionic species were D+3 and D+ at low and high arc currents, respectively. Changes in the electrical potential of the copper cup with respect to the anode produced negligible changes in the above data. A mild steel plasma expansion cup caused the magnetic field to diverge and intercept the cup walls, resulting in ion current density distributions that were flatter and more amenable to focusing than the ones with the copper cup. With the steel cup at anode potential, the ion mass distribution was similar to that from the copper cup; however, the ion energy distribution was asymmetrical about the anode potential with a peak about 10–20 V above anode potential. The total ion current from this mode of operation was about one-third the value from the copper cup. If the steel cup assumed floating potential, about 50 V below anode potential, the total current increased to the level observed from the copper cup and the ion energy distribution was similar to that observed with the copper cup but the current density distribution was much flatter than that of the copper cup. The ion mass distribution was 60%–70% atomic ions over the entire arc current range investigated. Based on these data, a modified plasma expansion cup was designed with tapered steel walls lined with a boron nitride insert. The overall performance of the duoplasmatron ion source with this cup was superior to any of the previous three modes of operation. The improved design uses a molybdenum anode insert which is far superior to copper in regard to erosion over extended operating times. A total beam current of 200 mA was produced at an arc current of 24 A.
Low background cold cathode ion source for molecular beam detection
Authors: Faubel M. , Holber W. M. , Toennies J. P.
Published: March 2003

An extractor gauge type electron bombardment ion source using carbon fiber bundles as field electron emitters is described. The cold cathode permits operation of the ionizer within a liquid He cooled cryopump. The high pumping speed for all molecules (except helium) together with its low background pressure make this ion source a very promising detector for crossed molecular beam scattering experiments.
New automatic heat flow calorimeter
Authors: Frauenfelder R.
Published: March 2003

A calorimeter was developed which is capable of measuring heats of reaction with high precision, without making use of a precision thermostat. In comparison with conventional heat flow calorimeters, the measuring time is reduced considerably by electronic means. The reproducibility is comparable to that of adiabatic calorimeters, while the operation is easier because no filling and weighing of water and temperature readings are necessary. The final result is indicated automatically.
High-flux beam source of fast neutral helium
Authors: Fahey D. W. , Schearer L. D. , Parks W. F.
Published: March 2003

A high-flux beam source of fast neutral helium has been constructed by extending the designs of previous authors. The source is a dc or pulsed electric discharge in an expanding gas nozzle. The beam produced has a flux on the order of 1015 atoms/s sr and a mean velocity on the order of 107 cm/s. The composition of the beam has been determined by the use of particle detectors and by the observation of the excitation of certain target gases. An upper bound of 3.7×10−5 has been estimated for the He(23S1)/He(1S0)beam density ratio and a value of 0.2 found for the He+/He(11S0) beam density ratio.
Technique for the measurement of the amplitude and phase velocity of a slow space charge wave on a relativistic electron beam
Authors: Gammel G. , Nation J. A. , Read M. E.
Published: March 2003

A technique is described for the measurement of the axial electric field of a slow space charge wave. The measurement employs a double probe arranged to give an output proportional to the rate of change of magnetic flux linking the probe loop. This output may be related to the electric field of the wave. Two such probes used in an interferometer arrangement allow for the measurement of the phase velocity of the wave.
Fluorescence polarization: measurements with a photon-counting photometer
Authors: Jameson David M. , Weber Gregorio , Spencer Richard D. , Mitchell George
Published: March 2003

A T-format, photon-counting polarization photometer was constructed to facilitate precise polarization measurements at low signal-to-noise ratios. The instrument optics and electronics are described. Several examples of the instrument’s performance are given, including measurements on picomolar fluorescein solutions at low excitation resolution and the excitation polarization spectrum of indole (2×10−4M) at a resolution of 5 Å.
New design of an ion cyclotron resonance cell capable of temperature variation over the range 80⩽T⩽450 K
Authors: Wren A. G. , Gilbert P. , Bowers M. T.
Published: March 2003

The design of an ICR cell capable of convenient operation over the temperature range 80⩽T⩽450 K is reported. Time–temperature plots indicate that the cell can undergo changes in temperatures of ΔT=100 K in 30–45 min. Thermal gradients in the cell are small, less than ±2 K. Factors that governed the design of the cell are discussed in detail, as are potential problem areas. The cell is tested by measuring two proton transfer equilibrium constants, one that shows a large temperature coefficient and the other a small temperature coefficient. In each case the results agree well with similar experimental data in the literature.
Polarization by a tilted absorbing glass plate
Authors: Walraven R. L.
Published: March 2003

Formulas for the response of an optical detector to the transmitted component of a tilted absorbing glass plate are derived in terms of the angle of incidence, the thickness of the plate, and the absorption coefficient and index of refraction of the glass. Numerical results are discussed for detectors of various sizes compared to the width of the incident beam and thickness of the plate.
BNC–JJ coaxial floating shield bakable and coolable vacuum feedthrough useful from dc to 4 GHz
Authors: Ishimaru Hajime
Published: March 2003

A floating (1011 Ω), bakable (300°C), coolable (liquid helium temperature) BNC–JJ-type coaxial vacuum feedthrough is described. It has a VSWR ⩽1.22 from dc to 1.3 GHz and ⩽1.35 from 2.0 to 4.0 GHz.
Two-dimensional spectral line emission reconstruction as a plasma diagnostic
Authors: Myers B. R. , Levine Morton A.
Published: March 2003

A technique for reconstructing point-by-point light emission from a plasma using a series of one-dimensional, line-of-sight measurements is described. The method, an adaptation of tomographic x-ray scans, does not assume any symmetry in the plasma, unlike an Abel inversion. Results from the Tormac IV toroidal bicusp device are presented, in which plasma light was collected by a 16-channel polychromator with 0.4-Å resolution and a 1-μs time response. Reconstructed plasma light emission with spatial, temporal, and wavelength resolution is then calculated. The profiles of reconstructed spectral lines (Stark broadened Hβ and Doppler broadened He ii 4686-Å lines from the 90% H, 10% He plasma) are used to monitor local plasma density and temperature. A spatial resolution of 2 cm in a 14×24 cm vessel, which is determined by the number of angles that the plasma is viewed from, is realized. This technique is particularly useful when a high-temperature plasma is surrounded and obscured by a low-temperature, highly emissive plasma near the vessel walls.
Technique for the measurement of spatial vorticity distributions
Authors: Francis M. S. , Kennedy D. A. , Butler G. A.
Published: March 2003

A method for measuring mean spatial vorticity content has been described for flows where the primary convective velocity (free stream) is larger than the mean crossflow components. Employing an ’’X’’-geometry hot-wire probe and linearized anemometer system in conjuction with a precision probe traversing mechanism, this relatively simple technique can be used to evaluate the circulation associated with various spatial contours. Errors associated with the technique are computed exactly and in simple linearized forms to illustrate its validity in a wide range of flows. A priori knowledge of the flow character and resultant careful selection of the integration paths for a given flow situation is observed to result in minimal measurement errors. Application to the problem of an isolated trailing vortex is presented as an example. Experiments at the trailing edge of a lifting wing confirm the accuracy of the method when compared with existing theories and other experimental data. The method can be extended to periodically driven unsteady flows using phase-lock techniques.
Generation and measurement of subpicosecond electron beam pulses
Authors: Hosokawa T. , Fujioka H. , Ura K.
Published: March 2003

The generation and measurement of subpicosecond electron beam pulses by the transverse-longitudinal combination gate system is described. The temporal property of the pulse gate is analyzed with the help of the longitudinal emittance diagram. Close agreement has been obtained between the calculated pulse width and the observed one which was measured by the Lissajous’s figure method. A beam pulse of 0.2 ps (FWHM) was produced.
Interference fringe signal generator and its application
Authors: Ohishi Tadanao
Published: March 2003

A fringe signal generator for checking performance of a fringe shift measuring system has been devised. A pair of fringe signals in phase quadrature are provided by the generator with an electric input signal. The accuracy of the outputs is about 0.01 fringe over 2.5 fringe and its response is up to 1 fringe/60 μs. Nonlinearity of a fringe shift measuring system was tested by the generator.
Phase fluorometer for measurement of picosecond processes
Authors: Haar H. -P. , Hauser M.
Published: March 2003

Time-dependent fluorescence processes can be investigated using a phase fluorometer with variable frequency. The high cutoff frequency of 500 MHz leads to a time-resolving power of about 1 ps.
Glass capillary for high resolution NMR measurements at pressures up to 400 MPa
Authors: Williams R. K.
Published: March 2003

A glass capillary for use in high resolution NMR spectroscopy at pressures up to 400 MPa is described together with the method of construction and use.
Ten-microsecond pulsed molecular beam source and a fast ionization detector
Authors: Gentry W. Ronald , Giese Clayton F.
Published: March 2003

We describe a pulsed gas valve which we have developed for use as a molecular beam source. In order to observe the performance of the pulsed beam source, we also have developed an ionization detector with a rise time of about 1 μs. The pulsed valve produces very intense supersonic molecular beam pulses of about 10 μs duration for light gases such as H2 and He, and of somewhat longer duration for heavier gases. As a new tool for the study of molecular collisions, the pulsed beam technique offers substantial advantages over the conventional continuous-beam method for experiments which are limited by the signal-to background ratio for scattered products.
Secondary particle collection in ion implantation dose measurement
Authors: Jamba Douglas M.
Published: March 2003

The measurement of ion implantation doses in the presence of secondary ions and electrons emitted from the target is discussed. A circuit and electrode geometry for obtaining accurate ion beam current measurements in the presence of both positive and negative secondary particles is presented.