Faraday Rotation of Microwave through Gaseous Plasmas

Abstract

There appears the elliptically rotated Faraday effect for microwaves transmitted through lossy plasmas with magnetic field. The detector signal of an electric field component of the wave through plasmas oscillates for the monotonous decrease of the plasma electron density, where the cyclotron frequency is higher than the applied frequency. It is shown that the electron density and the collision frequency can be cletei-Tnined from the maxima and the minima of the detector signal.
From the detected microwave signal through an afterglow plasma in a waveguide in pressures of 2 and 5 mmHg in Neon or Argon, the electron density decays from 10¹²-10¹⁰cm^-3 with time are determined for different magnetic fields from 3400 to 6000 Gauss. These decays show, reasonable values of trio recombination coefficient in the later period, where the electron energy rel, sxes to the thermal equilibrium with the gas temperature, because the recombination loss predominates for these afterglow plasmas with radial diffusion suppressed by the strong magnetic field.
The collision frequencies of electrons with ions, which predominate over those with neutral atoms under this experimental condition are determined and plotted versus the electron density. A plausible explanation is discussed for these values somewhat higher than the theoretical ones.