1952c
The following is a paper by H. Aspden published in The Journal of Scientific
Instruments, vol. 29, pp. 371-374, (1952).
A METHOD OF MEASURING THE MAGNETIC PERMEABILITY OF ROD
SPECIMENS
Abstract: A method is described by which the
permeability of open-ended rod specimens is measured by detecting changes in
flux density and field strength by search coil and fluxmeter means. A feature is
introduced whereby a repeated reversal of magnetizing field results in the
field-indicating fluxmeter adding all the field changes in the same sense so
that the customary compromise between accuracy and sensitivity involved in
direct measurements of field strength is avoided. The method is extended by
connecting in opposition the field search coil and the flux search coil so that
the above arrangement can be used as a sensitive flux-balance indicator and the
accuracy of a permeability measurement rendered substantially independent of
fluxmeter errors.
Commentary: This paper was written during a
period when the author was working for a Ph.D. degree which involved
experimental research on the eddy-current anomaly. See the related paper: [1956a].
However, this method was not used in the eventual experiments which were the
basis of that Ph.D. This paper was awarded a prize by the U.K. Institute of
Physics.
