Beam-Driven Growth of Lower Hybrid Wave in a Magnetized Relativistic Beam-Plasma System

In this work, a problem based on fluid theory of parametric decay of a lower hybrid wave in a magnetized relativistic beam-plasma system has been studied. The non-linear coupling of lower hybrid wave via beam mode excitation is numerically analysed. The lower-hybrid wave ( ω_p,k_p ) imparts energy and momentum to the electrons of the target plasma. The density fluctuation associated with the electron beam mode interacts with electron velocity and generates a non-linear current, driving sideband ( ω_s,k_s ), where ω_s=ω_p-ω_B , k_s=k_p-k_B on account of the pump wave. The excited sideband wave interacts with the pump wave, exerting a ponderomotive force on plasma electrons. This coupling drives the beam mode (the low frequency mode at ω_B,k_B ) . The beam driven instability’s growth rate in different beam density regions has been obtained with the dependency of parametric instabilities on the local plasma parameters. This finding suggests that the beam coupling that leads to parametric instability of the LH wave is mostly determined by electron dynamics.