ELECTRON-CYCLOTRON MASER THEORY FOR EXTRAORDINARY BERNSTEIN WAVES

Electron-cyclotron maser emission is investigated. in the regime where wave growth in the electrostatic Bernstein modes dominates (omega(p)/ Omega(e) > 1.5). A semirelativistic growth rate is derived assuming th at the wave dispersion is dominated by a cool background electron dist ribution and the instability is driven by a low-density I-lot loss-con e-like electron distribution. The properties of Bernstein wave growth are most strongly dependent on the relative temperatures of the hot an d cool electron distributions. For T-hot/T-cool greater than or simila r to 10, the fastest growing Bernstein waves are produced. at frequenc ies just below each cyclotron harmonic in Bernstein modes lying below the upper-hybrid frequency. For T-hot/T-cool less than or similar to 1 0; additional Bernstein modes above the upper-hybrid frequency are exc ited, with wave frequencies in each excited mode lying significantly a bove tile corresponding cyclotron harmonic. The dependence of Bernstei n wave growth on the relative hot and cool electron number densities a nd emission angle is also discussed.