Millimetre-wave second-harmonic generation in an underdense magnetoplasma with a density ripple

A high-power millimetre wave (ω1,k1) propagating through a magnetized plasma at an angle to a density ripple (0, k0) produces density perturbations (ω1,k1, k0). The density perturbations couple with the oscillatory velocity at (ω1, k1) to produce a nonlinear current at (2ω1, 2k1+k0) driving second-harmonic electromagnetic radiation. The efficiency of the process is sensitive to the angle between the density ripple and the millimetre wave.