ISSN: 0090-3973
Page Count: 8

Eddy Current Decay Resistivity Measurements Using a Digital Voltmeter

Hua, CY
Senior engineer,General Research Institute for Non-Ferrous Metals,

McDonald, LC
Project consultant,Rimkus Consulting Group, Inc.,TX,

Hartwig, KT
Associate professor,Texas A & M University,TX,

(Received 27 November 1995; accepted 29 July 1996)

Abstract

A digital voltmeter is shown to successfully capture the voltage decay signal during eddy current decay (ECD) measurements at cryogenic temperatures on low-resistivity specimens. The use of a voltmeter simplifies ECD measurements, typically made using a digital oscilloscope. An added benefit of using a voltmeter is that under certain circumstances, measurement precision exceeds that which is normally obtained with a preamplifier-digital oscilloscope combination. Results indicate that the best combination of instruments for capturing extremely weak signals (i.e., those with long exponential time constants) is a preamplifier-voltmeter configuration. Results of a comparative study using a preamplifier-digital oscilloscope configuration, a digital voltmeter alone and a preamplifier-digital voltmeter arrangement are presented and discussed.

Keywords:
cryogenic, digital voltmeter, eddy current decay, resistivity, time constant

Paper ID: JTE11323J
DOI: 10.1520/JTE11323J
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