The lowest order mode-mode coupling in weak plasma turbulence consists of three processes: the three wave resonance, resonant scattering and nonlinear plasma maser. The plasma maser interaction is a new nonlinear process in turbulent plasma. The process leads to up-conversion of wave energy from low frequency turbulent fields to high frequency waves through nonlinear interaction of waves and particles. Thus the process has potential importance to interpret numerous radiation phenomena in space and laboratory plasmas.

The plasma maser effect occurs when nonresonant as well as resonant plasma oscillations are present. The resonant oscillations are those for which the Cherenkov resonance condition is satisfied, while the nonresonant oscillations are those for which the neither the Cherenkov resonance condition nor the nonlinear Landau resonance conditions are satisfied.

Results of numerical simulation of E.M. wave interaction with Langmuir turbulence. [a] Growth rates vs. beam density, [b] Time history of electric field energy for different magnetic field strengths.

At Centre of Plasma Physics, we carry out both analytical and numerical research on various topics of plasma maser interaction.