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 that the wave dispersion is dominated by a cool background electron distribution and the instability is driven by a low-density I-lot loss-cone-like electron distribution. The properties of Bernstein wave growth are most strongly dependent on the relative temperatures of the hot and cool electron distributions. For T-hot/T-cool greater than or similar to 10, the fastest growing Bernstein waves are produced. at frequencies just below each cyclotron harmonic in Bernstein modes lying below the upper-hybrid frequency. For T-hot/T-cool less than or similar to 10; additional Bernstein modes above the upper-hybrid frequency are excited, with wave frequencies in each excited mode lying significantly above the corresponding cyclotron harmonic. The dependence of Bernstein wave growth on the relative hot and cool electron number densities and emission angle is also discussed.