Mw. Gillenwater et al., EDDY-CURRENT DECAY AND RESISTIVITY MEASUREMENTS ON LONGITUDINALLY GROOVED HIGH-PURITY ALUMINUM BARS, Journal of testing and evaluation, 26(4), 1998, pp. 320-328
The eddy current decay (ECD) method for determining electrical resisti
vity uses a relationship between the time constant of magnetic flux di
ffusion and resistivity. This method is shown to be valid for determin
ing the resistivity of solid high-purity aluminum cylinders with eight
equally spaced longitudinal grooves machined into the surface. The ef
fects of changes in groove dimensions for a 25.4-mm-diameter, supercon
ducting magnetic energy storage (SMES) conductor stabilizer are report
ed. Observations of machining, heat treatment, and material inhomogene
ity effects are discussed. It is found that the ECD time constant is d
ependent primarily on groove depth and that groove width has only a mi
nor influence. An empirical equation relating groove dimensions with t
he time constant and with resistivity is presented.