Acoustic generation in solid dielectrics excited by steep square-wave voltage edges under non-uniform electric field configurations

Steep edges of square-wave voltages can excite observable acoustic signals in solid dielectrics, yet the underlying source mechanism remains insufficiently understood, particularly in non-uniform electric field configurations. In this Letter, the acoustic force components responsible for edge-induced acoustic generation in a needle–plate dielectric specimen are analyzed, and the dependences of the response on voltage amplitude and edge time are experimentally verified. The needle-side acoustic wave exhibits a characteristic double-peak waveform distinct from the nearly single-peak response of a plate–plate specimen. Source-resolved analysis attributes this waveform to the combined contributions of interfacial surface forces and electrostrictive forces. The response further separates into geometry-background and space-charge-coupled components with quadratic and linear voltage-amplitude dependences, respectively. Both components decrease monotonically with increasing edge time and exhibit similar edge-time dependences. These findings reveal strong correlations of edge-induced acoustic signals with field geometry, voltage edge dynamics, and space-charge effects, highlighting their value for assessing insulation-state evolution.