New Mechanism for Electromagnetic Emission near the Geometric Mean Plasma Frequency

Abstract
We report the experimental observation and theoretical description of a previously unrecognized mechanism for electromagnetic emission from plasmas near the geometric mean plasma frequency. Very clear emissions were observed from the electric-field-dominated NASA Lewis bumpy torus plasma at a frequency which is inconsistent with familiar mechanisms of plasma emission. A theory based on a Penning-discharge-like beam-plasma interaction predicts a frequency in excellent agreement with the observations.