The acoustic field of the near radiation zone formed upon EMAC in metals

This paper analyzes the behavior of bulk types of waves generated by a circular bus with current by the magnetostriction mechanism in a normal polarizing field in a magnetic high-conductivity halfspace in relative proximity to a media boundary. Calculated dependences of the module of the amplitude and the angle characterizing the direction of radiation of bulk waves in the near zone are presented for radiators of different shapes. It has been shown that the acoustic field in the near radiation zone is a superimposition of waves that differ from purely longitudinal or shearing waves due to a considerable contribution of harmonics from the decaying part of the spectrum. The characteristic points of the field (the maximum amplitudes) decay abruptly and are shifted inward by curved trajectories; it is only in the far zone that they are transformed into straight lines directed at certain angles. Recommendations for determining the transition region between the zones are given.