Enhancement of Acoustic‐Electromagnetic Wave Coupling Across a Plasma‐Air Boundary

摘要

The linearized field equations for ion acoustic and electromagnetic waves in a low‐pressure gas discharge or semiconductor are considered. Boundary conditions at a density discontinuity and a plasma‐air surface are examined and expressions are derived for the reflected and transmitted fields excited by an incident acoustic wave. Numerical results for the power transmission through a plasma‐air boundary indicate that great enhancement can be obtained in a narrow frequency range by a boundary layer of reduced density and a thickness of an odd multiple of the acoustic half‐wavelength.