Experimental investigation of anomalous absorption of electromagnetic waves in a magnetized plasma

A left circularly polarized electromagnetic wave (f = 2.45 GHz) is launched into an overdense electron cyclotron plasma (n approximately 2 x 1011 cm-3, T/sub e/ approximately 8 eV). The wave is observed to be anomalously transmitted for a period of time after which it is essentially completely absorbed with a concurrent increase in electron temperature of up to 50 percent. At the time of absorption, radio frequency probe measurements indicate the excitation of electrostatic plasma waveguide modes at frequencies both below the electron cyclotron plasma frequency and above the electron plasma frequency. Measurements of the frequencies, wave numbers and azimuthal orders were made and have identified these waves as Gould-Trivelpiece type modes. The excitation and subsequent damping of these modes is interpreted to be the mechanism for the absorption of the incident left wave