RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

May 1988

Volume 59, Issue 5, pp. 693-818

Page 1 of 2 Pages Next Page | Jump to Page

JET x‐ray pulse‐height analysis system

D. Pasini, R. D. Gill, J. Holm, E. van der Goot, and A. Weller

Rev. Sci. Instrum. 59, 693 (1988); http://dx.doi.org/10.1063/1.1139812 (7 pages) | Cited 14 times

Full Text: | Download PDF

Show Abstract
The pulse‐height‐analysis (PHA) system installed on the Joint European Torus (JET) measures the plasma soft x‐ray emission (2–30 keV) with an energy resolution of 450 eV and a time resolution of 200 ms. This diagnostic includes three Si(Li) detectors, equipped with sets of remotely controlled apertures and filters, which view the plasma in the midhorizontal plane of the torus along a single tangential line of sight. Automatic analysis of the spectra yields the central electron temperature, the central concentrations of chlorine, chromium, and nickel, and Zeff. Simulations of the measured spectra using a radiation code provides the basis to construct a consistent picture of the soft x‐ray emission in the central region of JET plasmas.
Show PACS
52.70.La X-ray and γ-ray measurements
29.30.Kv X- and γ-ray spectroscopy
29.40.Wk Solid-state detectors

Improved bolometry system for reversed field pinch research

G. Miller, J. C. Ingraham, and L. S. Schrank

Rev. Sci. Instrum. 59, 700 (1988); http://dx.doi.org/10.1063/1.1139813 (9 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
A bolometry system for time and spatially resolved energy‐loss measurements on the ZT‐40M reversed‐field pinch is described. This system allows ∼100‐μs time resolution with a radiation detection limit of ∼100 mW/cm2 , in particularly noisy electromagnetic environments. The bolometer element fabrication using evaporative techniques and photolithography is discussed. Increased noise rejection is realized by using an oscillator/FM receiver electronics system based on 5‐MHz ac excitation of the resistor. An improved oscillator is described. Because resistive sensing is done at 5 MHz, pulsed heating currents may simultaneously be passed through the bolometer resistor and this allows for absolute in situ system calibration. We describe a new method of such calibration that is independent of the resistor geometry.
Show PACS
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
07.50.-e Electrical and electronic instruments and components
52.70.Ds Electric and magnetic measurements

Hollow ballistic pendulum for plasma momentum measurements

S. F. Goncharov, P. P. Pashinin, V. Y. Perov, R. V. Serov, and V. P. Yanovsky

Rev. Sci. Instrum. 59, 709 (1988); http://dx.doi.org/10.1063/1.1139814 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
A novel pendulum design—hollow ballistic pendulum—is suggested for plasma momentum measurements. It has an advantage over the pendula used earlier in laser plasma experiments of being insensitive to a momentum of matter evaporated and scattered by the pendulum wall exposed to the plasma, which usually exceeds plasma momentum to be measured. Simple expressions describing pendulum performance are derived, and requirements of shape and size are established. Using this kind of pendulum in experiments on laser acceleration of thin foils made it possible to measure the momentum of accelerated foil with an accuracy of about 10%.
Show PACS
52.70.-m Plasma diagnostic techniques and instrumentation
52.38.-r Laser-plasma interactions
52.25.-b Plasma properties

CO2 dissociation in sealed rf‐excited CO2 waveguide lasers

B. A. McArthur and J. Tulip

Rev. Sci. Instrum. 59, 712 (1988); http://dx.doi.org/10.1063/1.1139815 (4 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
A mass spectrometer has been used to study the gas composition in a sealed rf‐excited CO2 waveguide laser during operation. CO2 dissociation levels, at 53% to 71%, are similar to those reported for dc‐excited waveguide lasers and substantiate prior measurements on rf‐excited discharges. The degree of dissociation decreases with increasing pressure and xenon content, but increases as the proportion of helium in the gas mixture is increased. Dissociation has been found to be insensitive to the rf input power per unit discharge length over the range of 2.7 to 4.7 W/cm. This is believed to be the result of increased rates of water vapor outgassing at higher input power levels.
Show PACS
42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.55.Ah General laser theory
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light

Prism laser light‐scattering spectrometer

Benjamin Chu, Renliang Xu, Tadakazu Maeda, and H. S. Dhadwal

Rev. Sci. Instrum. 59, 716 (1988); http://dx.doi.org/10.1063/1.1139816 (9 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
A prism light‐scattering spectrometer capable of measuring both the angular distribution of scattered intensity and Rayleigh linewidth is described. The spectrometer employs a unique prism light‐scattering cell capable of making small‐angle self‐beating dynamic light‐scattering measurements down to a scattering angle of 2° and is able to achieve an optical coherence factor β∼0.9 routinely, with the theoretical limit for β being 1. The prism light‐scattering cell also permits refractive index measurements in the 1.33–1.60 range to a precision of 8×10−7 using a single‐axis lateral position sensor. It is a flow cell with potential as a detector for other analytical techniques once the cell volume can be minimized. The apparatus can be controlled by a computer for measurements, as well as acquisition, display, computation, and storage of data.
Show PACS
07.60.Rd Visible and ultraviolet spectrometers
42.87.-d Optical testing techniques
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation

Principle of a new reflectometer for measuring dielectric film thickness on substrates of arbitrary surface characteristics

B. L. Sopori

Rev. Sci. Instrum. 59, 725 (1988); http://dx.doi.org/10.1063/1.1139817 (3 pages)

Full Text: | Download PDF

Show Abstract
A reflectometer is described that can make accurate measurements of the thickness of a dielectric film on a large‐area substrate. The measured value does not depend on the surface characteristics of the substrate. Two basic principles that the new reflectometer invokes are: (i) the wavelength dependence of the integrated reflectance exhibits a minimum at a wavelength which can be related to the film thickness; and (ii) the reciprocity principle for integrated reflectance (i.e., the sample is illuminated with a light of wide angular distribution and the component of light reflected normal to the sample is measured). The instrument has applications in semiconductor industry in general and, in particular, in solar energy device fabrication. This instrument can also be used to measure the absolute reflectance.
Show PACS
07.60.Hv Refractometers and reflectometers
07.60.Fs Polarimeters and ellipsometers
42.87.-d Optical testing techniques
42.79.Wc Optical coatings

Measurements of electrical birefringence by using a transverse‐field Pockels cell as a compensator

Francisco Mendicuti

Rev. Sci. Instrum. 59, 728 (1988); http://dx.doi.org/10.1063/1.1139818 (9 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
An improved device for electrical birefringence measurements is described. The novel features of this apparatus include a new design of the Kerr cell and use of the Pockels cell as a compensator. These features show enhanced sensitivity and great improvement in reproducibility of results. A relationship between the intensity detected and the relative phase shifts in the Kerr and Pockels cells is determined by a matrix analysis of the amplitude of radiation passing through each optical element. Based on this analysis, a comparative study under different experimental configurations, as well as an evaluation of the effects of misalignments and methods to cancel the static birefringence, are made. From the results, the best experimental arrangement and procedure of measurement are deduced. Finally, the apparatus is checked by measuring Kerr constants (B) of several nearly isotropic solvents used for the study of polymers in solution.
Show PACS
07.50.-e Electrical and electronic instruments and components
07.60.-j Optical instruments and equipment
78.20.Jq Electro-optical effects

Refracting instrument for ultraviolet inverse photoemission spectroscopy

W. A. Royer and N. V. Smith

Rev. Sci. Instrum. 59, 737 (1988); http://dx.doi.org/10.1063/1.1139819 (4 pages) | Cited 12 times

Full Text: | Download PDF

Show Abstract
An instrument is described for k‐resolved ultraviolet inverse photoemission spectroscopy using a LiF lens monochromator and a rotatable high‐perveance electron gun. The energy resolution from all sources at ℏω=11 eV is 0.6 eV (FWHM). The angular spread of the incident electrons is calibrated using the properties of a well‐known and well‐characterized surface state on Cu(111), and is found to be 7°(FWHM).
Show PACS
07.60.Rd Visible and ultraviolet spectrometers
79.60.-i Photoemission and photoelectron spectra

Improved inverse photoemission detector

K. C. Prince

Rev. Sci. Instrum. 59, 741 (1988); http://dx.doi.org/10.1063/1.1139820 (2 pages) | Cited 12 times

Full Text: | Download PDF

Show Abstract
An inverse photoemission detector of the Geiger–Müller type is described, with a detection energy of 10.6 eV and resolution of 0.6 eV. The window material is MgF2 and the detecting gas is dimethyl ether, with argon as the multiplier gas. The detector offers a number of advantages compared with the conventional I2 /CaF2 detector, including a detection energy higher than that of previous detectors, insensitivity to temperature variations, and ease of handling because the detector gas is neither corrosive nor highly poisonous.
Show PACS
07.60.Rd Visible and ultraviolet spectrometers
79.60.-i Photoemission and photoelectron spectra

2π‐radian field‐of‐view toroidal electrostatic analyzer

D. T. Young, S. J. Bame, M. F. Thomsen, R. H. Martin, J. L. Burch, J. A. Marshall, and B. Reinhard

Rev. Sci. Instrum. 59, 743 (1988); http://dx.doi.org/10.1063/1.1139821 (9 pages) | Cited 20 times

Full Text: | Download PDF

Show Abstract
We describe a new type of electrostatic charged particle analyzer based on toroidal geometry. The analyzer features a 360°×10° (polar×azimuthal) field of view and a focal length in the polar direction significantly longer than that of similar devices based on spherical geometry. Extended focal length is a requirement for matching the electrostatic energy spectrometer with a second, mass‐resolving, analyzer. Laboratory tests show that the toroid design has a large geometric factor per unit of instrument weight, good energy‐angle resolution in the particle deflection plane, and sharp (1.0° FWHM) resolution at focus in the polar angle direction. The analyzer is well suited for use in satellite‐borne mass spectrometry and also as a stand‐alone electrostatic analyzer.
Show PACS
07.75.+h Mass spectrometers
95.55.-n Astronomical and space-research instrumentation

Bridged loop–gap resonator: A resonant structure for pulsed ESR transparent to high‐frequency radiation

Susanne Pfenninger, J. Forrer, A. Schweiger, and Th. Weiland

Rev. Sci. Instrum. 59, 752 (1988); http://dx.doi.org/10.1063/1.1139822 (9 pages) | Cited 56 times

Full Text: | Download PDF

Show Abstract
A new and inexpensive X‐band resonator structure for pulsed electron‐spin resonance and electron‐nuclear‐double‐resonance applications is introduced. The resonator consists of a bridged loop structure and is distinguished by a good reproducibility and reliability. It has a high filling factor and an adjustable Q value and is transparent to radio frequency fields with an upper limit >100 MHz. The inner diameter of 5 mm allows convenient sample access of standard 4‐mm quartz tubes in the temperature range between 4 and 300 K. Numerical computations of the resonant frequencies, the Q values, and the three‐dimensional distributions of the electromagnetic fields are presented. They are based on a discretization method for the solution of Maxwell’s equations and include all dielectric elements of the resonator structure. The field homogeneity in the sample area and the influence of the dimensions and the thickness of the metallic layers on field intensity, quality factor, and resonant frequency are determined experimentally. The performance of the resonator is demonstrated by a novel field‐swept echo‐induced electron‐spin‐resonance experiment with jumping magnetic field vectors.
Show PACS
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques
33.35.+r Electron resonance and relaxation

Computer‐controlled pulsed magnetic field gradient NMR system for electrophoretic mobility measurements

Timothy R. Saarinen and W. Stephen Woodward

Rev. Sci. Instrum. 59, 761 (1988); http://dx.doi.org/10.1063/1.1139823 (3 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
A computer‐controlled pulsed magnetic field gradient NMR (PFGNMR) system for making electrophoretic mobility and diffusion measurements is described. Emphasis is placed on the design and capabilities of the gradient and electrophoretic pulse generators. Various pulse sequences can be applied by the programmable gradient generator that can produce 0‐ to 10‐A current pulses for 0 to 13 ms and continuous currents from 0 to 50 mA. The pulse areas are reproducible to within approximately 1 ppm. A pair of opposed Helmholtz coils in the probe create linear magnetic field gradients during the current pulses. Electric fields are applied across a U‐tube electrophoretic cell by a 550‐V constant current generator.
Show PACS
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
82.45.-h Electrochemistry and electrophoresis

Sensitivity improvement of a Varian E‐109 EPR spectrometer with a low noise microwave amplifier

S. L. Dexheimer and M. P. Klein

Rev. Sci. Instrum. 59, 764 (1988); http://dx.doi.org/10.1063/1.1139824 (3 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
The installation of a low noise GaAsFET microwave preamplifier into a Varian E‐109 homodyne X‐band EPR spectrometer is described, and measurements of the resulting improvement in sensitivity as a function of microwave power are presented. Particular attention is paid to modification of the automatic frequency control (AFC) system to compensate for the preamplifier gain, which would otherwise result in instability of the AFC servoloop and decreased spectrometer performance at moderate microwave power levels. Specific details are provided for modification of the Varian E‐102 bridge, but the general approach is applicable to other spectrometers.
Show PACS
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
61.05.Qr Magnetic resonance techniques; Mössbauer spectroscopy (for structure determination only)
84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)

Measurement of infrared absorptivities and line shapes and the distortion of anvils in diamond‐anvil cells

D. D. Klug, Aurele Lavergne, and Edward Whalley

Rev. Sci. Instrum. 59, 767 (1988); http://dx.doi.org/10.1063/1.1139825 (5 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The infrared transmission of diamond and other transparent anvil apparatuses that contain absorbing samples, has been calculated as a function of frequency for planar anvils that are inclined to one another or that are distorted into parabolic shapes. At frequencies where the samples are completely transparent, the height of the interference fringes decreases with increase of frequency at nearly the same rate for both parabolically distorted and inclined anvils for which the maximum difference in optical path length of the sample is the same. Hence, the distortion of anvils in a typical experimental configuration have been measured up to a mean pressure on the anvil faces of 60 kbar. They are consistent with the predictions of elasticity theory that distortions occur at the rate of about 20 μm in 500 kbar. The predicted effect of such distortions on the absorbance, integrated area, and time autocorrelation function of the dipole moment is insignificant in a well‐designed experiment, and so all these properties can now be measured accurately at high pressures.
Show PACS
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
62.50.-p High-pressure effects in solids and liquids

Optical spectroscopy at cryogenic temperatures using a Block–Piermarini diamond‐anvil cell

M. Leroux, J. Leymarie, G. Méheut, and G. Neu

Rev. Sci. Instrum. 59, 772 (1988); http://dx.doi.org/10.1063/1.1139826 (4 pages) | Cited 13 times

Full Text: | Download PDF

Show Abstract
A simple experimental setup allowing low‐temperature high‐pressure spectroscopy, with in situ pressure adjustment, is described. A Block–Piermarini diamond‐anvil cell is used together with standard laboratory materials. Results of semiconductor photoluminescence studies, using argon as a pressure‐transmitting medium, are given as an illustration and are also used for the study of the pressure conditions. Pressure homogeneity is better than 100 MPa up to 6 GPa, and the residual uniaxial component of the stress can be lower than 100 MPa.
Show PACS
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
07.60.Rd Visible and ultraviolet spectrometers
78.55.-m Photoluminescence, properties and materials
62.50.-p High-pressure effects in solids and liquids

Low‐temperature sample‐rotating cryostat with two degrees of freedom for measuring the anisotropy of the upper critical field of superconductors

B. G. Pazol and D. M. Ginsberg

Rev. Sci. Instrum. 59, 776 (1988); http://dx.doi.org/10.1063/1.1139827 (2 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
An apparatus is described for measuring the anisotropy of the upper critical field, Hc2 . It can rotate a sample through large angles about two orthogonal axes in a magnetic field. Three Hall probes determine the orientation of the sample relative to an applied magnetic field, giving an angular precision of less than 0.1°. This is an order of magnitude improvement in angular precision over previously reported devices. Its performance, operation, and advantages are discussed.
Show PACS
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
74.25.Op Mixed states, critical fields, and surface sheaths
74.70.Dd Ternary, quaternary, and multinary compounds (including Chevrel phases, borocarbides, etc.)

Using the fast Fourier transform to determine the period of a physical oscillator with precision

C. E. Goldblum, R. C. Ritter, and G. T. Gillies

Rev. Sci. Instrum. 59, 778 (1988); http://dx.doi.org/10.1063/1.1139828 (5 pages) | Cited 13 times

Full Text: | Download PDF

Show Abstract
Measuring the period of torsion pendulums with precision has long been a formidable challenge in gravitation experiments, particularly those measuring the Newtonian gravitational constant G. An alternative method to fitting the position signal of the pendulum to a sine wave is the use of the power spectrum generated by the fast Fourier transform (FFT) as the source of information from which the period of oscillation can be determined. There are, however, known limitations to the use of a FFT to measure the period of a physical oscillator with precision. These limitations include two effects due to the finiteness of the duration of the sinusoidal data record and one effect due to the uncertainty of the starting phase of the oscillator relative to the window imposed by this duration. We have done a phenomenological study of the FFT using a desktop computer to imitate a precision oscillator having the physical characteristics of a finite damping constant and drift in the zero potential‐energy position. Also, we have taken extensive data with a torsion pendulum, and analyzed them in this way. These studies show that for a real oscillator, such as the classical torsion pendulum, the FFT is a useful tool for determining the period of oscillation with the precision usually associated with larger, more complex, fitting algorithms. With good signal‐to‐noise ratio and under conditions appropriate to a torsion pendulum, the FFT method can measure the frequency or period to five parts in 106 or better.
Show PACS
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation
02.70.-c Computational techniques; simulations
02.30.Uu Integral transforms
02.30.Vv Operational calculus
45.05.+x General theory of classical mechanics of discrete systems

Oscillating vane for measuring speed of gas flow

H. H. Jonsson and B. Vonnegut

Rev. Sci. Instrum. 59, 783 (1988); http://dx.doi.org/10.1063/1.1139829 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Experiments with an oscillatory vane in a wind tunnel reveal that the vane’s oscillation frequency is directly proportional to the square root of the dynamic pressure of the flow. The linear relationship is observed for flow speeds up to the speed of sound in air, argon, and helium. The vane’s oscillations are a measure of mass flow, or if used on an aircraft, of indicated air speed. In constant density media the oscillation frequency is directly proportional to flow speed, and a simple count of the oscillations is a measure of distance traveled. At given ambient temperature and pressure, the vane’s frequency is the same at the speed of sound for all gases, irrespective of their molecular weight.
Show PACS
47.80.-v Instrumentation and measurement methods in fluid dynamics
51.90.+r Other topics in the physics of gases (restricted to new topics in section 51)

Two approaches to construction of vibrating probes for electrical current measurement in solution

Carl Scheffey

Rev. Sci. Instrum. 59, 787 (1988); http://dx.doi.org/10.1063/1.1139830 (6 pages) | Cited 25 times

Full Text: | Download PDF

Show Abstract
Two systems are described that implement the vibrating probe method for recording the voltage field in electrolyte solutions. The method has a spatial resolution of 5–40 μm and very low drift. The first system is a simple device that allows inexpensive but reliable use of the method to record the field in one dimension. It is based on a metal electrode vibrating along a line, with power supplied by a single piezoelectric bimorph. The second is a more complex system, with computer support, that measures the field in two dimensions, acquires the data to the computer disk, and plots the field measurement on a video image of the experimental preparation. A π‐shaped linkage of three bimorphs is used to move the metal electrode in two dimensions. Motor micrometers with optical encoders are used to move the electrode and monitor its position.
Show PACS
07.50.-e Electrical and electronic instruments and components
82.45.-h Electrochemistry and electrophoresis

Dedicated microprocessor system to control laser Doppler velocimetry measurements and to reduce data

D. V. Srikantaiah, T. Philip, and W. W. Wilson

Rev. Sci. Instrum. 59, 793 (1988); http://dx.doi.org/10.1063/1.1139831 (4 pages)

Full Text: | Download PDF

Show Abstract
A dedicated microprocessor system has been developed exclusively to control and reduce data from a two‐component laser Doppler velocimeter (LDV) which uses counter‐type signal processors. The system control and data‐acquisition/validation software residing in the EPROMs has made the LDV system a stand‐alone instrument. The measurements are initiated through a hex keypad where each key is programmed for a specific function including traverse of the optics. During measurements, blocks of 16 kbytes of raw data are transferred to a mass storage for detailed postmeasurement analysis. The system is also provided with a general purpose interface bus (GPIB) to enable access to a centralized data‐acquisition network. The overall LDV system is portable and has been successfully used in field measurements at various magnetohydrodynamic (MHD) facilities and in other laboratory applications.
Show PACS
07.05.Hd Data acquisition: hardware and software
07.05.Kf Data analysis: algorithms and implementation; data management
07.05.Rm Data presentation and visualization: algorithms and implementation
47.80.-v Instrumentation and measurement methods in fluid dynamics

High‐precision portable instrument to measure position angles of a video camera for bird flight research

W. G. Delinger and W. R. Willis

Rev. Sci. Instrum. 59, 797 (1988); http://dx.doi.org/10.1063/1.1139778 (5 pages)

Full Text: | Download PDF

Show Abstract
A battery‐powered portable instrument for research on the aerodynamics of bird flight has been built to automatically measure and record the horizontal and vertical angles at which a video camera is pointed as an operator videotapes a soaring bird. Each angle was measured to a precision of about 20 arc seconds or better. Two complete systems were constructed, and a triangulation method was used so the same bird in flight could be videotaped by two cameras at different locations to establish the radius vectors from an origin to the bird. The angle information was generated by rotary transducers attached to the camera mounts, and the angle values along with timing data were stored in the semiconductor memory of a single‐board computer. The equipment has been successfully tested in the field and promises to have a wider application where a portable instrument is required to measure angles to high precision.
Show PACS
07.68.+m Photography, photographic instruments; xerography
42.30.-d Imaging and optical processing

Micro Kelvin probe for local work‐function measurements

H. Baumgärtner and H. D. Liess

Rev. Sci. Instrum. 59, 802 (1988); http://dx.doi.org/10.1063/1.1139779 (4 pages) | Cited 27 times

Full Text: | Download PDF

Show Abstract
This article describes a miniaturized Kelvin probe with a lateral resolution of 40 μm. Applied to a conducting or semiconducting surface, it allows a microscopic imaging of the difference of the work functions between the Kelvin probe and a sample. The signal resolution is better than 6 mV with an integration time of 300 to 400 ms, which is sufficient for most of the applications. The necessary steps to optimize the signal processing are described in detail.
Show PACS
07.50.-e Electrical and electronic instruments and components
73.40.Cg Contact resistance, contact potential
81.70.-q Methods of materials testing and analysis
84.32.Tt Capacitors

State‐machine digital pulse generator

E. Y. Sidky, E. A. Wachter, and T. C. Farrar

Rev. Sci. Instrum. 59, 806 (1988); http://dx.doi.org/10.1063/1.1139780 (5 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
An architecturally simple yet versatile memory‐state‐based digital pulse generator (or state machine) has been developed for control of instrumentation with PC‐compatible microcomputers. The pulse‐programming device uses parallel memory allocation to allow simultaneous output‐state and address change capabilities. The pulse sequence is loaded into parallel sections of resident memory as a program consisting of output states, state durations, and partial pointers to succeeding states. The complete pointers are generated by concatenation of these address bits with the outputs of duration and loop counters, making complex jumps and loops possible. Minimum event duration and timing resolution is limited only by memory access time; fast or slow memory can be selected based on individual needs. The memory used in the device described has access times of 120 ns, allowing clock rates as high as 8 MHz. The cost of this device is under $200.
Show PACS
84.30.Ng Oscillators, pulse generators, and function generators
07.50.Ek Circuits and circuit components
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques

Drive mechanism for a surface force apparatus

Clifford Luesse, John Van Alsten, George Carson, and Steve Granick

Rev. Sci. Instrum. 59, 811 (1988); http://dx.doi.org/10.1063/1.1139781 (2 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
A technique is described for micropositioning a surface forces apparatus with low mechanical and thermal drift. The technique is less exacting and more stable than competing ones.
Show PACS
07.10.-h Mechanical instruments and equipment

Effect of mechanical agitation on fuse opening switch efficiency

W. M. Lee and R. D. Ford

Rev. Sci. Instrum. 59, 813 (1988); http://dx.doi.org/10.1063/1.1139782 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
It is demonstrated that an exploding wire fuse opening switch comprising aluminum wire in water can be made more efficient by mechanically agitating the wire while it is being exploded. The electrical current flowing through the wire collapses faster, generating a higher voltage output when the arrival time of the agitating source at the wire material is well selected. The agitation appears to facilitate the dispersion of the molten metal within the water tamper so that the electrical energy input necessary to open the switch is reduced.
Show PACS
84.32.Vv Fuses
52.75.Kq Plasma switches (e.g., spark gaps)
07.50.-e Electrical and electronic instruments and components
84.32.Dd Connectors, relays, and switches
Page 1 of 2 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close