Reciprocity relations in an isotropic compressible multifluid plasma

Reciprocity relations in an isotropic compressible multifluid plasma with collisions are theoretically investigated. The reciprocity theorem for current sources and electromagnetic fields which is often employed for a free space is found to be guaranteed in such a medium. The reciprocity is shown to be valid also for the case that an antenna is surrounded by an abrupt vacuum sheath under a physically permissible boundary condition. Furthermore, the reciprocity theorem is established for electric charge sources and number density of wave perturbed particles under the condition that there is no collisions among perturbed particles of different species. It is also shown that the similar reciprocity relation holds for the quasistatic approximation without any restrictions. Finally, as an application of the reciprocity theorem, a general expression giving antenna receiving voltages for incident electrostatic waves such as an electron plasma wave and an ion acoustic wave are obtained.