Optimization of eddy current transducers (surround coil)

This paper provides a rational approach to the design of surround coil transducers for eddy current testing by maximizing the product of filling factor and empty coil Q. It is shown that reasonable criteria for coils whose inner diameter lies in the range from .1 cm to 11. cm are (assuming operation at a frequency below self resonance): coil length to ID ratio should be in the range of 1.5-2.5, wall thickness to ID ratio should be in the range .13-.20, and the wire size should be selected so that the coil losses at operating frequency are only a few percent above the dc resistance.