Momentum source of the plasma maser

The plasma maser, an interesting nonlinear process in plasma, is an effective means of energy up-conversion in frequency from Langmuir turbulence to the electrostatic Bernstein mode. It is shown here that the primary momentum and energy source of the plasma maser is the external magnetic field, which is not the case for the standard mode-mode coupling processes. For strongly magnetized plasma (${\mathrm{\Omega }}_{\mathit{e}}$≥${\mathrm{\omega }}_{\mathit{p}\mathit{e}}$, where ${\mathrm{\Omega }}_{\mathit{e}}$ and ${\mathrm{\omega }}_{\mathit{p}\mathit{e}}$ are the electron cyclotron frequency and the plasma frequency, respectively), the growth rate of the Bernstein mode arises from the polarization term. The growth rate is large in contrast to the previous ion-sound-turbulence case. These results have potential importance in the interpretation of anomalous radiation phenomena in astrophysical, laboratory, and fusion plasmas.