Resonance cones in a warm plasma for finite magnetic fields

The resonance cone structure excited by a localized source is studied theoretically and experimentally for a warm plasma with a finite, uniform magnetic field. The electrostatic Green’s function is evaluated by asymptotically expanding it in the limit where the observation point is far from the source. Results are obtained that are valid for all angles and for all frequencies below the upper hybrid. The theory predicts the functional dependence of the angular location of the main resonance cone peak and the angular spacing between interference peaks on the physical parameters. Experimental parameter studies were made to check the predicted functional dependence; it was found to produce a good fit to the data. Both density and temperature can be found from these measurements; thus, resonance cone measurements are a useful diagnostic technique in any magnetoplasma in which antennas can be inserted.