Faraday rotation of microwave fields in an electron cyclotron resonance plasma

An electron cyclotron resonance (ECR) plasma is created with 2.45-GHz linearly polarized microwaves, which propagate in the direction of the magnetic field. Measurements of the relative power and polarization angle versus z have been made within the first few centimeters of the quartz entry window. As the microwave electric field enters the plasma, it rotates while becoming elliptically polarized then circularly polarized. The rotation angle versus z and the component of the microwave field along the major axis of the polarization ellipse versus z are explained by cold plasma dispersion theory.