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

Nov 1991

Volume 62, Issue 11, pp. 2523-2836

Page 2 of 3 Pages Previous Page Next Page | Jump to Page

Characteristics of a surfatron driven ion source

Y. Hajlaoui, L. Pomathiod, J. Margot, and M. Moisan

Rev. Sci. Instrum. 62, 2671 (1991); http://dx.doi.org/10.1063/1.1142198 (8 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
A small, lightweight ion source based on a surface‐wave sustained plasma is investigated. Previously designed to be a 2 mA, 3 keV krypton ion launcher in an on board spacecraft experiment, its operation is extended to several common gases at various operating frequencies and extraction voltages. It is built around a fused silica discharge tube that has one end fitted with a two‐grid extraction system. This tube is enclosed by a surface‐wave launcher (surfatron) operated between 750 and 1000 MHz, and the discharge is sustained with only 35 W. The beam is neutralized by electrons emitted by a tungsten filament. Ion current densities extracted at a few kilovolts lie in the range 10–40 mA/cm2, depending upon the gas used. The largest ion current is obtained with hydrogen: 8.5 mA at 5 kV. Variations in the source performances with the gases used are analyzed using the ‘‘beam relative perveance’’ concept and the surfatron equivalent circuit model.
Show PACS
29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
52.80.Tn Other gas discharges

A new two‐dimensional particle detector for a toroidal electrostatic analyzer

R. M. Tromp, M. Copel, M. C. Reuter, M. Horn von Hoegen, J. Speidell, and R. Koudijs

Rev. Sci. Instrum. 62, 2679 (1991); http://dx.doi.org/10.1063/1.1142199 (5 pages) | Cited 70 times

Full Text: | Download PDF

Show Abstract
We describe a new two‐dimensional detector for the detection of ions scattered from a solid target, analyzed in energy and scattering angle by a toroidal electrostatic analyzer. The detector resolves the scattering angle with a resolution of 0.4° over a range of 25°, and the ion energy with a resolution of 120 eV over a range of 2000 eV, at 100 keV ion energy. The energy resolution of the spectrometer was improved with a factor 4 relative to its previous performance with a one‐dimensional scattering angle detector, while−at the same time−the dose efficiency (count/μC) was improved by a factor 5–10.
Show PACS
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
68.37.Vj Field emission and field-ion microscopy

High‐voltage deflection plate driver for the scanning‐beam switch

Stanley Humphries

Rev. Sci. Instrum. 62, 2684 (1991); http://dx.doi.org/10.1063/1.1142200 (5 pages)

Full Text: | Download PDF

Show Abstract
The scanning‐beam switch is a novel device to generate intense rf radiation for applications to electron accelerators. Operation is based on the transverse deflection of a high‐current sheet electron beam by an oscillating electric field. Amplifier experiments require a high‐voltage ac driver for beam deflection. This article describes a driver that combines a commercial high‐power pulsed triode with a resonant step‐up transformer. In initial tests, the device generated ac voltages up to ±12 kV at 50, 150, and 250 MHz.
Show PACS
29.20.-c Accelerators
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Triggered vacuum flashover switch for high‐power applications

J. C. Kellogg, J. R. Boller, R. J. Commisso, D. J. Jenkins, R. D. Ford, W. H. Lupton, and J. D. Shipman

Rev. Sci. Instrum. 62, 2689 (1991); http://dx.doi.org/10.1063/1.1142201 (6 pages)

Full Text: | Download PDF

Show Abstract
A command triggered, high‐power, surface‐flashover closing switch that operates in vacuum has been developed for use on a prototype inductive‐storage pulsed power generator, Pawn. This vacuum flashover switch isolates the high‐pressure‐gas tamped wire fuse from a second opening switch. The switch consists of an insulating ring sandwiched between electrodes. Plasma and ultraviolet light from eight small spark discharges driven by a 5 keV pulse initiate a flashover across the switch insulator. The entire triggering unit resides inside one of Pawn’s metallic conductors. The switch can be triggered after holding off voltage for ≂15 μs. Normally, switch closure occurs at 22–45 kV. Time to closure at a voltage of ≂30 kV is ≂320 ns, with a typical jitter of ±50 ns. Peak current is typically ≂1 MA. Current density in the switch is approximately 25 kA/cm2. The average risetime of the fuse output current pulse can be varied by a factor of 2 by triggering the switch at different closing voltages.
Show PACS
52.75.Kq Plasma switches (e.g., spark gaps)
84.32.Dd Connectors, relays, and switches
84.60.Ve Energy storage systems, including capacitor banks

Poloidal magnetic field measurement system in JT‐60

Nobuhiro Nishino, Hirotaka Kubo, Akira Sakasai, Yoshihiko Koide, Nobuo Akaoka, Tatsuo Sugie, Yoshimitu Tsukahara, Takao Ito, and Hiroshi Takeuchi

Rev. Sci. Instrum. 62, 2695 (1991); http://dx.doi.org/10.1063/1.1142202 (5 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
A diagnostic system using a helium beam for local poloidal magnetic field measurements (Zeeman polarimeter system) has been constructed. The Zeeman spectrum of the helium 31P‐21S line was observed in JT‐60. The intensity and energy of the neutral helium beam were up to 0.6 A and 200 keV, respectively. Resolution of the Zeeman polarimeter was 0.01 nm which was realized by using a Littrow‐type spectrometer. Photon counting efficiency was 0.065. Moreover, an in situ wavelength calibration could be done, using an Ar laser, within an error of 0.001 nm.
Show PACS
52.70.Ds Electric and magnetic measurements
07.60.Fs Polarimeters and ellipsometers

Simultaneous measurement of ion and electron temperatures in the scrape‐off layer of a small tokamak

R. P. da Silva and I. C. Nascimento

Rev. Sci. Instrum. 62, 2700 (1991); http://dx.doi.org/10.1063/1.1142203 (9 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
This article describes a system composed of an electrostatic ion probe associated with an electronic circuit designed and constructed to be used in the scrape‐off layer of the TBR‐1 tokamak for simultaneous measurements of local electron and ion temperatures. The electronic circuit is discussed. Details of the mechanical structure and dimensions of the probe can be found in another article [Rev. Sci. Instrum. 57, 2205 (1986)]. The circuit is composed of a sweep generator followed by an amplifier. The sweep time can be varied from 50 μs to 50 ms and the probe voltage amplitude from 0 to 200 V. The circuit supplies a maximum current of 250 mA, is short‐circuit protected, and provides cable capacitance neutralization. The ion current is detected by a current transformer sensitive to currents as low as 20 μA. The total probe current is measured by the voltage drop in a resistor inserted in the circuit. The system has been tested in the TBR‐1 boundary plasma and showed good performance with a time resolution better than 500 μs. The obtained results showed that, for TBR‐1 boundary plasma, the ion temperature is about two times the electron temperature.
Show PACS
52.70.Nc Particle measurements
52.70.Ds Electric and magnetic measurements
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
07.50.-e Electrical and electronic instruments and components

Hard x‐ray continuum crystal spectrograph for inertial confinement fusion (ICF) diagnostics

A. J. Burek, C. J. Armentrout, C. R. Bird, R. E. Frazier, J. B. Geddes, and D. F. Gorzen

Rev. Sci. Instrum. 62, 2709 (1991); http://dx.doi.org/10.1063/1.1142204 (10 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
We describe absolutely calibrated instrumentation for measuring hard x‐ray continuum produced during laser irradiation of ICF targets. The instrumentation includes a crystal spectrograph and two collimated filtered scintillators. The absolutely calibrated crystal spectrograph achieves high sensitivity to x‐ray continuum over the energy range of 5 to 35 keV with continuous energy coverage and a resolving power E/ΔE between 20 and 100. Time integrated spectra are recorded and stored electronically on a shot basis using two dimensional charge coupled device (CCD) camera readout of a proximity focused MCP detector close coupled to the x‐ray diffracting crystals. The filtered scintillators provide discrete, time‐resolved, high energy channels for recording integrated continuum in the 40–60 and 60–90 keV bands. End‐to‐end calibration of the crystal spectrograph was performed over the design energy interval. We discuss instrument design, calibration, and alignment and the factors affecting sensitivity and resolving power.
Show PACS
07.85.-m X- and γ-ray instruments
78.70.-g Interactions of particles and radiation with matter
79.20.Ds Laser-beam impact phenomena
52.70.La X-ray and γ-ray measurements

Photometric calibration of soft x‐ray and p‐terphenyl coated visible photodiodes in the 180–1500 eV range for fusion plasma spectroscopy

D. Stutman, S. Kovnovich, M. Finkenthal, A. Zwicker, and H. W. Moos

Rev. Sci. Instrum. 62, 2719 (1991); http://dx.doi.org/10.1063/1.1142205 (4 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The efficiencies of x‐ray ultraviolet silicon, and p‐terphenyl coated visible photodiodes have been measured in the 180–1500 eV range using a K radiation‐Manson source. It is found that the quantum efficiency (electrons/photon) of the silicon diode varies between 25 and 400 in the above‐mentioned range; the p‐terphenyl coated diode is by two orders of magnitude less performing at the high‐energy end of the range considered, but approaches the efficiency of the silicon diode at 100 Å. Such diodes with built‐in amplifiers, coated with scintillator and thin layers of metal films, can be efficiently used in spectroscopic diagnostics of magnetically confined plasmas.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
52.70.La X-ray and γ-ray measurements
07.85.-m X- and γ-ray instruments

Simple cooled CCD camera for beam diagnostics

Vladimír Cambel, Ján Sudek, Alexander Dmitrievich Kovalenko, Vladimir Ivanovich Datskov, and Mikhail Alexandrovich Voevodin

Rev. Sci. Instrum. 62, 2723 (1991); http://dx.doi.org/10.1063/1.1142522 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
A simple system for beam positioning and spatial distribution diagnostics based on a cooled charge coupled device (CCD) camera, scintillation screen, and optics has been developed. Standard methods of recording beam profiles are different for low and high intensity beams, which complicates readout techniques. The main advantage of our system is its adaptability for intensity range 103–1012 particles/cm2/pulse. The system was tested at the Dubna synchrophasotron complex. Protons and nuclei beam profile and position monitoring in mentioned intensity range and energy range of 10 MeV to 10 GeV was provided. A CCD camera is used in wavelengths interval 400–1100 nm. The hardware, software, and cryogenics of this system are described. Effects of fixed pattern noise and dependence of nonuniformity of response on wavelength are shown and some results of beam diagnostic are presented.
Show PACS
07.77.-n Atomic, molecular, and charged-particle sources and detectors
85.30.Tv Field effect devices

A 1.5–4 K detachable cold‐sample transfer system: Application to inertially confined fusion with spin‐polarized hydrogen fuels

N. Alexander, J. Barden, Q. Fan, and A. Honig

Rev. Sci. Instrum. 62, 2729 (1991); http://dx.doi.org/10.1063/1.1142206 (9 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
A compact cold‐transfer apparatus for engaging and retrieving samples at liquid‐helium temperatures (1.5–4 K), maintaining the samples at such temperatures for periods of hours, and subsequently inserting them in diverse apparatuses followed by disengagement, is described. The properties of several thermal radiation‐insulating shrouds, necessary for very low sample temperatures, are presented. The immediate intended application is transportable target shells containing highly spin‐polarized deuterons in solid HD or D2 for inertially confined fusion experiments. The system is also valuable for unpolarized high‐density fusion fuels, as well as for other applications which are discussed.
Show PACS
28.52.Cx Fueling, heating and ignition
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
67.25.bh Films and restricted geometries

Cryopumping of atomic hydrogen

V. G. Luppov, M. Mertig, T. Roser, B. S. van Guilder, B. Vuaridel, Yu. M. Melnik, and A. F. Prudkoglyad

Rev. Sci. Instrum. 62, 2738 (1991); http://dx.doi.org/10.1063/1.1142207 (4 pages)

Full Text: | Download PDF

Show Abstract
The pumping speed for the cryopumping of an atomic hydrogen beam was measured. Measurements were made for cryocondensation, cryosorption, and differential pumping. The pumping speed for atomic hydrogen was observed to be much smaller than the pumping speed for molecular hydrogen. It is believed that this is due to the energy released during the recombination of the atomic hydrogen.
Show PACS
07.30.Cy Vacuum pumps
29.90.+r Other topics in elementary-particle and nuclear physics experimental methods and instrumentation (restricted to new topics in section 29)

A novel transient pulse viscometer for fluid viscosities at high pressures and elevated temperatures

B. B. Maini and S. Kokal

Rev. Sci. Instrum. 62, 2742 (1991); http://dx.doi.org/10.1063/1.1142208 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
This article describes the design and principle of operation of a new capillary unsteady‐state pulse viscometer for measuring the viscosities of fluids at high pressures and elevated temperatures. The asymptotic solution for the flow of a fluid in a capillary tube under a transient pressure gradient that decays at a rate proportional to the fluid flux in the tube is derived. The apparatus is relatively inexpensive to manufacture since it does not require a constant flow pump. Furthermore, it does not require large volumes of the fluid being measured and is comparatively faster than other conventional steady‐state viscometers. The accuracy of the viscometer is comparable to or better than the commercial steady‐state viscometers. The relevant flow equations are derived for calculating viscosity from measured differential pressure decay signals.
Show PACS
47.80.-v Instrumentation and measurement methods in fluid dynamics
89.20.Bb Industrial and technological research and development
66.20.-d Viscosity of liquids; diffusive momentum transport

End effect in a coaxial cylindrical viscometer

Hiroshi Kobayashi, Takeshi Nashima, Yoshizo Okamoto, and Fumito Kaminaga

Rev. Sci. Instrum. 62, 2748 (1991); http://dx.doi.org/10.1063/1.1142209 (3 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
The end effect in a coaxial cylindrical viscometer was determined as an effective length of an inner cylinder (bob) using the multiple bob method. In this viscometer, the data are for a rotating bob and not for a rotating cup. The end correction appears to increase over the Reynolds number 10, even in low viscosity and Newtonian liquids. It is shown that a conical end of the bob and a wide gap between the bob and cup give a larger end correction. The visualization of the liquid flow at the bottom of the bob makes it clear that the stream lines enter into the annular gap even in Couette flow, which is supposed to disturb the flow in the gap. With the increment of the Reynolds number, these entrances become larger, although the flow is not Couette but Taylor and turbulent flows.
Show PACS
47.80.-v Instrumentation and measurement methods in fluid dynamics
47.27.-i Turbulent flows

Improved multilaser/multiparameter flow cytometer for analysis and sorting of cells and particles

John A. Steinkamp, Robert C. Habbersett, and Richard D. Hiebert

Rev. Sci. Instrum. 62, 2751 (1991); http://dx.doi.org/10.1063/1.1142210 (14 pages) | Cited 17 times

Full Text: | Download PDF

Show Abstract
An improved multilaser instrument has been developed for quantitative analysis and separation of biological cells and particles. Argon ion, krypton ion, and dye lasers are employed as excitation sources to sequentially illuminate cells labeled with multiple fluorochromes as they pass through an improved flow chamber that incorporates an electronic cell‐volume sensor and an optical measurement region. Detectors located on the axis of each excitation beam are used to measure axial light loss and forward light scatter. Multicolor fluorescence is measured using a five‐channel detector located orthogonal to the laser beam(s)‐cell stream intersection(s). Sequential measurements are made on a cell‐by‐cell basis to provide pulse height, area, and width signals that are made coincident in time by analog delay modules to increase data throughput. Analog electronics are used to compute real‐time ratios, sums, and differences of signals. Up to eight signals are acquired and displayed as single‐parameter frequency distribution histograms and bivariate diagrams using a microcomputer. Processed signals also activate cell sorting according to computer‐controlled preselected parametric criteria. The unique measurement capabilities and other new features designed into this instrument represent marked technological improvements over our previous system.
Show PACS
87.80.-y Biophysical techniques (research methods)

A versatile system for stable generation of uniform droplets

Gary L. Switzer

Rev. Sci. Instrum. 62, 2765 (1991); http://dx.doi.org/10.1063/1.1142211 (7 pages) | Cited 18 times

Full Text: | Download PDF

Show Abstract
A system for the production of liquid droplets of uniform size and velocity is described. The precise control of the operating fluid provided by this system allows the generator to function in a droplet‐on‐demand, burst, or continuous mode of operation. The basic component of the uniform droplet generator is a radially contracting piezoelectric cylinder which forces liquid through a glass‐capillary nozzle. Droplet diameters ranging from 5 to 500 μm have been produced by appropriate selection of nozzle aperture and operating mode. Further control of size, velocity, and interdroplet spacing is exercised through the voltage‐ and fluid‐control elements of the system. In addition to its ability to operate in any orientation, the droplet generator is designed with a small cross section and a water cooling feature for operation in coflowing, elevated‐temperature environments. The uniform‐droplet‐generation system has exhibited long‐term stability in operations ranging from a single isolated droplet to a stream of calibration‐standard droplets separated by center‐to‐center spacings of less than two diameters. Its capabilities in controlling droplet development and dynamics make it an attractive candidate for use in a wide range of liquid‐droplet applications.  
Show PACS
06.60.Ei Sample preparation (including design of sample holders)

A vibrating fiber microbalance for measuring layer‐by‐layer adsorption on graphite

L. Bruschi and G. Torzo

Rev. Sci. Instrum. 62, 2772 (1991); http://dx.doi.org/10.1063/1.1142212 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
This article describes an improved version of the graphite fiber microbalance, a device that was recently proved to be a useful tool for investigating adsorption phenomena. Hydrodynamic effects, that may yield large errors in the calculation of the adsorbed mass, if not properly evaluated, are carefully accounted for. An accurate measurement of the film coverage is obtained by using a correction to Stokes equations in the region of semiballistic regime that is much simpler than the slip theory used by other authors.
Show PACS
06.30.Dr Mass and density
68.55.-a Thin film structure and morphology

A gold/platinum thermocouple reference table

M. Gotoh, K. D. Hill, and E. G. Murdock

Rev. Sci. Instrum. 62, 2778 (1991); http://dx.doi.org/10.1063/1.1142213 (14 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
The thermoelectric voltage of the gold/platinum thermocouple has been measured over the range 0–962 °C by comparison with calibrated platinum resistance thermometers. From 0 to 500 °C, the measurements were carried out in stirred liquid baths; from 660 to 964 °C, they were carried out in a pressure‐controlled sodium‐filled heat pipe furnace that provided an isothermal intercomparison environment. Measurements were also made in the metal freezing points of indium, tin, zinc, antimony, and silver, at the melting point of gallium, and at the liquidus point of the silver‐copper eutectic. By fitting the measured thermoelectric voltages to a single eighth‐degree polynomial in temperature by the method of least squares, a reference function is obtained for the Au/Pt thermocouple that provides emf as a function of temperature (ITS‐90) to within ±10 mK from 0 to 962 °C. The Au/Pt thermocouple merits serious consideration for precise temperature measurements as its stability approaches that of the high‐temperature platinum resistance thermometer.
Show PACS
07.20.Dt Thermometers
06.20.F- Units and standards

A wide‐range superconductor thermal sensor for low‐temperature measurement

M. V. S. Lakshmi, K. Ramkumar, and M. Satyam

Rev. Sci. Instrum. 62, 2792 (1991); http://dx.doi.org/10.1063/1.1142214 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
This paper aims at describing a low‐temperature thermal sensor based on superconductor films which can be designed to have required variation of resistance with temperature through an appropriate geometry. Further, it has been shown that the temperature range can be varied to some extent by controlling the bias current.
Show PACS
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures

The systematic uncertainty in the calibration of the Langavant calorimeter

M. Balbás, J. I. Díaz, F. Gascón, and A. Varadé

Rev. Sci. Instrum. 62, 2795 (1991); http://dx.doi.org/10.1063/1.1142215 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
A mathematical study is made of the systematic uncertainty in the Langavant calorimeter calibration, determining the most influent variables being able to optimize the method. The influence of calibration constants on the determination of the heat of hydration of a cement is analyzed. Accuracy modification of several measuring instruments is suggested and imprecisions correction in the UNE 80‐118‐86 Spanish Standard and in the NF P 15‐436‐88 French Standard are proposed.
Show PACS
07.20.Fw Calorimeters

An automated, high precision unit for low‐pressure physisorption

W. S. Borghard, E. W. Sheppard, and H. J. Schoennagel

Rev. Sci. Instrum. 62, 2801 (1991); http://dx.doi.org/10.1063/1.1142216 (9 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
A physisorption apparatus with very high sensitivity has been constructed. It is capable of accurately measuring adsorption and desorption isotherms of gases on solids in the pressure range of 10−5–1000 Torr. This is particularly useful for investigating argon sorption on catalysts and catalyst supports, e.g., FCC, reforming and hydroprocessing catalysts; zeolites; and pillared layered materials. The isotherms contain information about micropore and mesopore size distribution, BET surface area, etc. The operation of the unit and the analysis of isotherm data are both fully automated. Details of the equipment and the software are described.
Show PACS
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Radio frequency signal processing with a monolithic four‐quadrant multiplier

Miroslav Kasal, Ivan Hruby, Piercarlo Mustarelli, and Sergio Scotti

Rev. Sci. Instrum. 62, 2810 (1991); http://dx.doi.org/10.1063/1.1142217 (6 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
A new monolithic and linear four‐quadrant multiplier allows replacement of traditional hybrid‐based circuits used in frequency conversion, and in‐phase or amplitude modulation schemes. We demonstrate the advantages of this approach by evaluating the performances of a wideband amplitude and phase modulation unit built around the 500 MHz multiplier AD834. Key specifications of the unit we assembled are an 80 dB attenuation range, a 100 ns response time, a 360° range of phase shift, and an accuracy up to 0.02°. The device suits the phase and amplitude modulation needs of a nuclear magnetic resonance spectrometer.  
Show PACS
84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques

Noise measurements on silicon J‐FETs at low temperature using a very high Q superconducting resonator

F. Ayela, J. L. Bret, and J. Chaussy

Rev. Sci. Instrum. 62, 2816 (1991); http://dx.doi.org/10.1063/1.1142218 (6 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
Noise voltage and noise current measurements have been carried out at different temperatures on two kinds of low‐noise silicon J‐FET at moderately high frequencies up to 100 kHz. We have made careful noise current measurements by constructing a very low‐loss superconducting resonator working in the kHz frequency range, whose quality factor reaches 3×105. At 10 kHz, the measured noise energy lies between 1.1 and 1.8×10−24 W/Hz for both types of transistors, but the ratio between the noise voltage and the noise current exhibits pronounced differences depending on the device under test.
Show PACS
85.30.Tv Field effect devices
07.50.-e Electrical and electronic instruments and components
07.55.-w Magnetic instruments and components

Dead time correction of time distribution measurements

F. Esposito, N. Spinelli, R. Velotta, and V. Berardi

Rev. Sci. Instrum. 62, 2822 (1991); http://dx.doi.org/10.1063/1.1142219 (6 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
We report in this article an analysis of the distortion of the time distribution due to the dead time of the detection chain. The special case of distributions coming from a pulsed source is considered and a relatively simple method for the reconstruction of the true time distribution is given. The method is applicable in both extended and nonextended dead times. It can be applied to correcting an experimental time distribution and, if the shape of the distribution is known, to deducing the true rate of events from that measured by a counter. An experimental method to simulate a pulsed source with a controllable mean production rate is also shown; the time distributions obtained from this source have been used as test distributions to prove the reliability of the reconstruction procedure.
Show PACS
06.30.Ft Time and frequency
29.50.+v Computer interfaces
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques
07.05.-t Computers in experimental physics

Errors in the measurement of non‐Gaussian noise spectra using rf spectrum analyzers

M. H. Anderson, R. D. Jones, J. Cooper, and S. J. Smith

Rev. Sci. Instrum. 62, 2828 (1991); http://dx.doi.org/10.1063/1.1142168 (3 pages)

Full Text: | Download PDF

Show Abstract
We discuss the nature of errors which may occur when the spectra of random signals not obeying Gaussian statistics are measured with typical rf spectrum analyzers. These errors depend on both the noise statistics and the process used to detect the random signal after it has been passed through a narrow bandpass filter within the spectrum analyzer. In general, for random signals not obeying Gaussian statistics, the output of the bandpass filter must be measured with a square law detector if the resulting measurement is to be strictly proportional to the power spectrum of the input signal. We compare measurements of the power spectra of non‐Gaussian noise using a commerical spectrum analyzer with its resident envelope detector, with measurements by the same analyzer fitted with a square law detector. Differences of about 5% were observed.
Show PACS
74.20.-z Theories and models of superconducting state
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques

Simulated lock‐in amplifier deep level transient spectroscopy

C. A. B. Ball and A. B. Conibear

Rev. Sci. Instrum. 62, 2831 (1991); http://dx.doi.org/10.1063/1.1142169 (2 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
A technique is presented for the analysis of digitally recorded capacitance transients in order to determine the energy and capture cross section of deep levels. The method is essentially a digital simulation of the measurement carried out by a lock‐in amplifier. This technique in principle allows trap parameters to be determined in a single temperature scan. The more efficient use of data brought about by the method permits a detailed study of the Arrhenius plot and in particular gives insight into cases where the capacitance transient is nonexponential. The method may be adapted to allow more efficient data usage in conventional lock‐in amplifier deep level transient spectroscopy.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close