Lower hybrid destabilization of trapped electron modes in tokamak and its consequences for anomalous diffusion

TL;DR

This paper investigates how lower hybrid waves interact with trapped electron modes in tokamaks, leading to destabilization and increased anomalous diffusion, which impacts plasma confinement.

Contribution

It introduces a new understanding of parametric coupling effects between lower hybrid waves and trapped electron modes in tokamaks.

Findings

Destabilization of short wavelength modes

Enhanced anomalous diffusion coefficient

Growth of trapped electron drift waves

Abstract

Parametric coupling of lower hybrid pump wave with low frequency collisionless/weakly collisional trapped electron drift wave, with frequency lower than the electron bounce frequency is studied. The coupling produces two lower hybrid sidebands. The sidebands beat with the pump to exert a low frequency ponderomotive force on electrons that causes a frequency shift in the drift wave, leading to the growth of the latter. The short wavelength modes are destabilized and they enhance the anomalous diffusion coefficient.