Preliminary tests to design an EMAT with pulsed electromagnet for high temperature

Abstract

Electromagnetic Acoustic Transducers (EMATs) typically make use of permanent magnets since they provide high magnetic fields with a compact size. For high temperatures, the relatively low Curie point of suitable magnets is a disadvantage (e.g. 100-150 degrees C in NdFeB). An alterative approach is to employ an electromagnet, which can be used at elevated temperatures without cooling. Large power supplies and cooling are required for DC current electromagnets capable of producing magnetic flux densities comparable to NdFeB magnets. If one uses a pulsed current electromagnet, synchronous to the excitation current of the EMAT coil, the high field can be obtained with a relatively low duty cycle and insignificant heating of the coil. We present the preliminary results in the design of an EMAT, intended for high temperature operation using a pulsed electromagnet