Laboratory Plasmas: Summary Report

Three papers were presented in this session, two on plasma resonances and one about Bernstein‐mode electrostatic waves. M. P. Bachynski and B. W. Gibbs (RCA Laboratories, Montreal, Canada) gave the results of their experiment which concerns electrostatic resonances excited in a layer of isotropic plasma by means of plane transverse electromagnetic waves incident from free space. The angle of incidence was small, i.e., θ = 0° ∼ 12°. Incident waves are polarized, circularly and linearly, and have a fixed frequency, 9.2 GHz. The incident power density was of the order of 0.1 mw cm −2 . The thickness of the plasma slab was 1.56 free‐space wave lengths. Two electric dipoles were used as receiving antennas, one totally immersed in the plasma and the other placed outside the plasma. The immersed dipole was oriented normal to the plasma‐slab boundary and consequently nearly longitudinal to the incident wave. Strong electric fields were observed in the regions under conditions in which the frequency of the incident wave equaled the plasma frequency, and the electric vector of the incident field was in the plane of incidence. These strong fields seem to be longitudinal electrostatic fields, since only weak electric fields of longitudinal direction were observed if the incident electric field was perpendicular to the plane of incidence.