Low-threshold induced side-scattering instability in the edge transport barrier at O-mode ECRH experiments in magnetic fusion devices

TL;DR

This paper predicts a low-threshold side-scattering instability caused by lower hybrid wave trapping in tokamak edge barriers, which can broaden power deposition profiles in ECRH experiments, impacting current and future fusion devices.

Contribution

It introduces the concept of a low-threshold absolute parametric decay instability induced by wave trapping in the edge barrier, affecting microwave power deposition.

Findings

Prediction of wave trapping in tokamak edge barriers.

Identification of a low-power-threshold instability.

Potential impact on power deposition profiles in fusion devices.

Abstract

The lower hybrid wave trapping in a tokamak edge transport barrier is predicted. This effect makes possible excitation of the low-power-threshold absolute parametric decay instability leading to side-scattering of the ordinary microwave pump in the electron cyclotron resonance heating experiments. The instability can result in broadening of the power deposition profile both in present day machines and in ITER.