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

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

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

May 1971

Volume 42, Issue 5, pp. 561-732

Page 1 of 3 Pages Next Page | Jump to Page

A Low Temperature Glass‐Ceramic Capacitance Thermometer

W. N. Lawless

Rev. Sci. Instrum. 42, 561 (1971); http://dx.doi.org/10.1063/1.1685170 (6 pages) | Cited 46 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
Dielectric measurements are reported on capacitance thermometers based on SrTiO3 crystallized from glass at 1100 and 1200°C. Multilayer experimental units, approximately 5×2×1 mm, were fabricated using pilot plant facilities and measured from 1.7 to 300 K. If both the capacitance and loss tangent are measured, the range of the 1100°C crystallized thermometer is from at least 1.7 to 300 K. For capacitance measurement alone, the thermometer range is below 72 K, and in this range the capacitance varies smoothly and monotonically with temperature, becoming linear below 5.2 K. The sensitivity is largest in this linear region and averages 250 pF⋅K−1 for the 1100°C crystallized thermometers. The self‐heating at 4.2 K is about 70 pW (5 kHz, 7 mV) and decreases with decreasing temperature. The effect of a magnetic field on the thermometer was measured in an open Dewar of liquid helium at four frequencies in fields up to 80 kG. The measured changes were ≤±1 mK and are interpreted as fluctuations in the bath temperature rather than an intrinsic magnetocapacitance effect. The response time between 4.2 and 300 K is at least 70 K⋅sec−1. The main disadvantage of the thermometer is a transient (∼30 min) capacitance instability which is equivalent to a ≤30 mK change before stabilization. Once stabilized, the thermometer repeats to about ±2 mK when compared to a germanium thermometer, and repeats to ±13 mK on cyclically plunging into liquid helium (15 cycles) in the unstabilized case. This instability is apparently due to helium migration into the unencapsulated sensor body. The polar properties of glass crystallized SrTiO3, on which the thermometer is based, are briefly discussed, and comparisons are made with two other capacitance thermometers reported in the literature.

Studies of a Glass‐Ceramic Capacitance Thermometer between 0.025 and 2.4 K

W. N. Lawless, Ray Radebaugh, and R. J. Soulen

Rev. Sci. Instrum. 42, 567 (1971); http://dx.doi.org/10.1063/1.1685171 (4 pages) | Cited 10 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
Capacitance measurements from 0.025 to 2.4 K are reported for capacitance thermometers (made from an SrTiO3 glass‐ceramic crystallized at 1100 and 1203°C), two of which were the ones reported in the previous article. It was found that the 1200‐type thermometer has a useful thermometric range down to 0.06 K and a linear C‐T region down to 0.5 K. The 1100‐type thermometer has a useful range down to 0.110 K and a linear region down to 1.1 K. The measured data do not appear to be influenced by self‐heating or adiabatic correction effects. Both thermometers display an unexpected increase in capacitance with decreasing temperature below their monotonically decreasing ranges. The 1100‐type thermometer displays the more pronounced increase, with C∝T−1 from 0.100 to 0.025 K. It is argued that this T−1 behavior is due to the onset of an ultralow temperature phase transition in the glass crystallized SrTiO3, and the possibility of using this effect to achieve adiabatic depolarization cooling is discussed.

Studies of a Glass‐Ceramic Capacitance Thermometer in an Intense Magnetic Field at Low Temperatures

L. G. Rubin and W. N. Lawless

Rev. Sci. Instrum. 42, 571 (1971); http://dx.doi.org/10.1063/1.1685172 (3 pages) | Cited 30 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
The effect of an intense magnetic field on an 1100‐type capacitance thermometer (made from an SrTiO3 glass‐ceramic crystallized at 1100°C) was accurately measured at five temperatures between 1.5 and 4.2 K. At each manostatically maintained temperature, the capacitance changes were measured five times between B=0 and B=14 T, and it was found that these changes did not exceed the measurement uncertainty, ±0.3 pF≅±1 mK. Similar results were obtained on a second 1100‐type thermometer. Some suggestions are made for the use of this type of thermometer in magnetic field experiments.

Simulating Atmospheric Radio Noise from Low Frequency through High Frequency

Earl Bolton

Rev. Sci. Instrum. 42, 574 (1971); http://dx.doi.org/10.1063/1.1685173 (4 pages)

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
Generally it is too costly or otherwise not feasible to conduct performance tests on a radio communication system under conditions of actual atmospheric radio noise because this noise is nonstationary. Accurate simulation of desired conditions solves this difficulty. Magnetic tape recordings were made of atmospheric radio noise from low frequency through high frequency. The recordings were computer analyzed and were used as a model for the design of an atmospheric noise simulator. The simulation is valid and accurate for the limited available data base.

Measurement of the Thermal Pressure Coefficient (∂P∕∂T)v of Molten Salts

B. Cleaver, B. C. J. Neil, and P. N. Spencer

Rev. Sci. Instrum. 42, 578 (1971); http://dx.doi.org/10.1063/1.1685174 (3 pages)

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A method for the determination of the thermal pressure coefficient (∂P∕∂T)v or γv for molten salts up to 400°C and 400 bars is described. The results, which are considered to be accurate to ±3%, are compared with previous work.

Refrigerating Vapor Bath

L. J. Puckett, M. W. Teague, and D. G. McCoy

Rev. Sci. Instrum. 42, 580 (1971); http://dx.doi.org/10.1063/1.1685175 (4 pages) | Cited 6 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A simple and inexpensive refrigerating vapor bath has been developed for the purpose of cooling gas line traps. The cooling medium in the bath is the cold vapor from liquid nitrogen. The temperature regulation range is from −196 to ∼0°C. For a glass‐isolated stainless steel gas trap the liquid nitrogen consumption rate was less than ☒ liter∕24 h at temperatures between −130 and −196°C.

A Comparison of Ta, W, and Pt‐8%W Surface Ionization Detectors for Fast Potassium Atom Detection

J. F. Cuderman

Rev. Sci. Instrum. 42, 583 (1971); http://dx.doi.org/10.1063/1.1685176 (4 pages) | Cited 11 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
Data are presented which describe and compare the behavior of Ta, W, and Pt‐8%W surface ionization detectors for fast potassium atom detection. The potassium atom energy in these experiments covered the range from thermal energy to 500 eV.

A Low Cost Versatile Arc Melter

F. J. Cadieu, L. F. Cooley, and D. H. Douglass

Rev. Sci. Instrum. 42, 587 (1971); http://dx.doi.org/10.1063/1.1685177 (2 pages) | Cited 3 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
We have designed and built an arc melter which uses an inexpensive Pyrex pipe cross for a controlled atmosphere chamber. An argon jet has been incorporated into the electrode holder which provides both dynamic flushing and rapid quenching capabilities.

Paired Comparison Tests of the Relative Signal Detected by Capacitive and Floating Langmuir Probes in Turbulent Plasma from 0.2 to 10 MHz

J. Reece Roth and Walter M. Krawczonek

Rev. Sci. Instrum. 42, 589 (1971); http://dx.doi.org/10.1063/1.1685178 (6 pages) | Cited 20 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
Paired comparison measurements of the spectrum of electrostatic potential fluctuations in a steady state turbulent plasma confined in a magnetic mirror geometry have been made with capacitive and floating Langmuir probes over the frequency range from 0.2 to 10.0 MHz. For the experimental conditions investigated (5×107≤ne≤5×108∕cm3, 8≤Te≤38 eV, 350≤Ti≤930 eV, Bmax=1.0 T), no significant difference in the relative frequency response was observed below 4.0 MHz. At about this frequency, however, the signal detected by the floating Langmuir probe dropped off relative to that of the capacitive probe. The source resistance of the turbulent fluctuations sensed by the Langmuir probe was about 400 Ω. At higher frequencies (from 7.0 to 10.0 MHz) a signal was detected by the floating Langmuir probe that was not detected by the capacitive probe. This spurious signal may be confused with the turbulent fluctuations of the plasma in the absence of paired comparison tests.

Corona Discharge Anemometer and Its Operational Hypothesis

Prateen V. Desai and William C. Johnston

Rev. Sci. Instrum. 42, 595 (1971); http://dx.doi.org/10.1063/1.1685179 (6 pages) | Cited 1 time

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
The paper presents an outline of the physical mechanism of corona discharge between a highly stressed anode and a large plate cathode as applied to the operation of a new type of anemometer. An operational hypothesis is proposed for the anemometer with reference to its kinematic and electrostatic principles of performance. Experimental results are presented to justify the hypothesis and the calibration of the probe. A discussion of the probe sensitivity to yaw of gas stream is included.

Measurement of the Index of Refraction of Some Molten Ionic Salts

Jules Marcoux

Rev. Sci. Instrum. 42, 600 (1971); http://dx.doi.org/10.1063/1.1685180 (3 pages) | Cited 1 time

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A simple method for measuring the index of refraction of molten salts is described. The indices of CaCl2, KBr, NaCl, and KCl are given at wavelengths ranging from 4000 to 7000 Å. Dispersion curves are given. Comparison is made with values obtained by another method.

A Solid State Light Pen and Computer Interface for the Tektronix 611 Storage Oscilloscope

R. A. Leskovec and P. R. Bevington

Rev. Sci. Instrum. 42, 602 (1971); http://dx.doi.org/10.1063/1.1685181 (4 pages)

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A solid state light pen has been developed to accommodate the phosphor characteristics of the Tektronix 611 storage oscilloscope. Computer interfacing for the 'scope includes remote control of the storage mode and expansion of both X and Y axes by a factor of 1–8 with variable trace positioning.

A Thermistor Anemometer for the Measurement of Very Low Air Velocities

Francisco S. Martino and Preston E. McNall

Rev. Sci. Instrum. 42, 606 (1971); http://dx.doi.org/10.1063/1.1685182 (4 pages) | Cited 3 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A new thermistor anemometer is described for measuring low air velocities of 0–100 cm∕sec. A theoretical performance curve (anemometer output vs air velocity) was calculated for the instrument. When compared with the experimental performance data, good correlation existed. Several characteristics of the anemometer were investigated experimentally. The instrument displayed excellent sensitivity and good stability (reproducibility of the calibration curve at a given ambient temperature). The output was not affected by the air flow direction. The anemometer output was affected by changes in ambient temperature, and the use of calibration curves for various ambient temperatures is suggested.

A Precision Variable Luminance Source for Photometric Applications

William V. Goodell

Rev. Sci. Instrum. 42, 610 (1971); http://dx.doi.org/10.1063/1.1685183 (3 pages)

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A variable luminance source having precise photometric characteristics is described. The instrument utilizes the principle of the integrating sphere, efficiently using the flux from a 45 W quartz‐halogen lamp to provide luminances from 1 to 500 fL in a continuous range. The color temperature was kept within ±100 K over the entire luminance range by geometric means without the introduction of aberrative optical elements. Luminance uniformity and stability of ±2.5 and ±0.5%, respectively, were maintained over a 42 mm output aperture for the tungsten spectrum from 0.4 to 1.4 μ.

Resistance of a Silicon Bronze at Low Temperatures

D. B. Sullivan

Rev. Sci. Instrum. 42, 612 (1971); http://dx.doi.org/10.1063/1.1685184 (2 pages) | Cited 10 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A specially prepared silicon bronze is shown to be quite insensitive to magnetic field and temperature change at liquid helium temperatures. The temperature coefficient of resistance is of the order of a few parts per million per degree over the range 2–10 K and the change in resistance at a flux density of 1 T (104 G) is about 10 ppm.

Polymers at Low Temperatures: Increasing Thermal Diffusivity in Specific Heat Measurements

Jesse L. Cude and Leonard Finegold

Rev. Sci. Instrum. 42, 614 (1971); http://dx.doi.org/10.1063/1.1685185 (2 pages) | Cited 7 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
The thermal diffusivity of samples of powdered high polymers can be increased (at least in the temperature range 1–20 K) by compressing them with copper powder. Hence thermal relaxation times in specific heat measurements can be decreased. The specific heat of the copper is relatively small and is well known. Calorimeter vessels are then unnecessary.

Circuit for Approximate Computation of Reciprocal of Time Delay to Maximum Cross Correlation

W. R. Tompkins and M. Intaglietta

Rev. Sci. Instrum. 42, 616 (1971); http://dx.doi.org/10.1063/1.1685186 (3 pages) | Cited 3 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A circuit was developed to measure the inverse time delay to maximum cross correlation between two stationary time varying voltages. The first voltage is delayed in a sample‐and‐hold circuit whose sampling frequency is swept. When the delay between the two signals is smaller than a quarter of the period of the fundamental, the sample‐and‐hold voltage is directly multiplied with the downstream voltage. When the delay is greater than a quarter of the period of the fundamental, the sample‐and‐hold signal is multiplied by the sample‐and‐hold value of the second signal, sampled at the same rate, 180° later. The filtered product for both cases has a maximum when the sampling frequency is inversely proportional to twice the delay to maximum cross correlation.

Apparatus to Rotate Samples Rapidly at Temperatures Less than 2 K in High Transverse Magnetic Fields

Wendell H. Potter

Rev. Sci. Instrum. 42, 618 (1971); http://dx.doi.org/10.1063/1.1685187 (8 pages) | Cited 4 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A system is described that allows rapid rotation of a sample at speeds up to 103 rps at temperatures less than 2 K in large transverse magnetic fields. It uses an He gas turbine with hydrostatic He gas bearings. A very compact, efficient counterflow heat exchanger was developed to cool the bearing and drive gas to 15 K. The system was developed specifically to produce high proton polarizations using the spin refrigerator technique, but is applicable to other experimental situations requiring high speed rotation at low temperatures in large transverse magnetic fields.

An Apparatus for Magnetic Measurements at High Pressure

R. W. Vaughan, C. F. Lai, and D. D. Elleman

Rev. Sci. Instrum. 42, 626 (1971); http://dx.doi.org/10.1063/1.1685188 (4 pages) | Cited 4 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A nonmagnetic high pressure cell capable of being used for a variety of magnetic measurements to over 100 kilobars is described. A Bridgman anvil type of cell, it has a 3–5 mm3 sample volume and is suitable for both pulsed and wide line nuclear magnetic resonance (NMR) measurements. In addition to a detailed description of the apparatus used for wide line NMR measurements, the use of the high pressure cell for magnetoresistance and susceptibility measurements is described.

A Wien Filter for Use as an Energy Analyzer with an Electron Microscope

G. H. Curtis and J. Silcox

Rev. Sci. Instrum. 42, 630 (1971); http://dx.doi.org/10.1063/1.1685189 (8 pages) | Cited 41 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
An electron optical system is described which is suitable for energy loss analysis in an electron microscope. A focusing spectrometer of the Wien type has been added underneath the column of a Hitachi HU11A electron microscope. After passing through the microscope, the electrons are slowed down before entering the spectrometer and reaccelerated to the detection point. Appropriate control of the electron trajectories into the Wien analyzer is achieved with a quadrupole field lens which makes it possible to use a long entrance slit. The energy resolution of the analyzer is limited by the width of the entrance slit which is adjusted to match the beam spread (1.5 eV). It can be made large (250 μ) compared with that of the Möllenstedt analyzer (5 μ), thereby passing much higher intensity through the analyzer and increasing the system flexibility.

Improved Method of Spinning Rotors to High Speeds at Low Temperature

J. W. Beams

Rev. Sci. Instrum. 42, 637 (1971); http://dx.doi.org/10.1063/1.1685190 (3 pages) | Cited 1 time

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A technique is described for spinning rotors of almost any size up to rotational speeds limited only by their strength, at liquid helium temperatures. The rotor is spun on the lower end of a long vertical stainless steel hypodermic needle tube shaft which connects to an air turbine drive above the apparatus. Electrical leads from the rotor are brought out through the hollow shaft and liquid mercury contacts. A convenient low noise system of liquid mercury electrical connections is described.

Precision Beam Location

E. N. Sickafus

Rev. Sci. Instrum. 42, 640 (1971); http://dx.doi.org/10.1063/1.1685191 (4 pages)

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A method for precise positioning of a beam on a given target is described. The technique employs a time dependent bias applied to the relative target beam position and frequency tuned detection of an associated flux that is coherently sensitive to changes in the primary beam. A location reference is determined which is the centroid of the convolution product of the target shape function and the beam profile function.

The Behavior of Type K Thermocouples in Temperature Measurement: The Chromel P‐Alumel Thermocouples

M. Campari and S. Garribba

Rev. Sci. Instrum. 42, 644 (1971); http://dx.doi.org/10.1063/1.1685192 (10 pages) | Cited 2 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
A study has been made on the origin of internal errors of type K and particularly of Chromel P‐Alumel thermocouples. Physical and chemical nonuniformities fixed in the materials and subsequent modifications occurring in the system set a lower limit to the error band within which it is not legitimate to expect any better degree of accuracy. Effects of chemical attack, ordering, and cold work were specially considered. It appears that a kinetic model accounting for time dependence may be envisaged. Some basic recommendations are made for all cases.

A Miniature Turbulence Gauge Utilizing Aerodynamic Lift

Thomas E. Siddon

Rev. Sci. Instrum. 42, 653 (1971); http://dx.doi.org/10.1063/1.1685193 (4 pages) | Cited 4 times

Online Publication Date: 4 November 2003

Full Text: | Download PDF

Show Abstract
An advanced version of the aerofoil probe turbulence gauge is described. The new device uses an axisymmetric lifting body sensor of 2.4 mm diameter coupled directly to a miniature preamplifier unit (6.35 mm diam). The output voltage varies linearly with the v or w component of turbulence. The device has uniform sensitivity and good signal‐to‐noise ratio over a nominal frequency range of 10–10 000 Hz. A discussion of calibration procedures and application considerations is included.

Random Pulse Train Generator with Linear Voltage Control of Average Rate

J. A. Hanby and S. J. Redman

Rev. Sci. Instrum. 42, 657 (1971); http://dx.doi.org/10.1063/1.1685194 (6 pages) | Cited 1 time

Online Publication Date: 4 November 2003

Full Text: | Download PDF


See Also: Erratum

Show Abstract
An electronic instrument which generates a train of constant amplitude pulses occurring at random times is described. The average pulse rate of this process is a linear function of a controlling voltage. The intervals between successive pulses form a renewal process and the probability density of these intervals may be varied from an exponential distribution to a gamma distribution of variable form. Statistical measurements on the pulse train are described which support the claims on its statistical properties.
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close