Plasma maser with cyclotron resonance

The plasma-maser process, including whistler mode turbulence and a test Langmuir wave, is considered for weakly magnetized plasma ${\omega }_{\mathrm{pe}}{\mathrm{>\Omega }}_e,$ where ${\omega }_{\mathrm{pe}}$ and ${\Omega }_e$ are the electron plasma and cyclotron frequency, respectively. The cyclotron resonant interaction between electrons and whistler mode is effective for the growth of the Langmuir wave through the plasma-maser process. The unstable test Langmuir wave and the whistler mode propagate in opposite directions. The direct coupling contribution exactly cancels out with the reverse absorpting effect due to the quasi-linear effect. The polarization coupling contribution gives the plasma-maser effect. The theory can explain a recent numerical simulation.