ECRH beam broadening in the edge turbulent plasma of fusion machines

TL;DR

This paper develops analytical models to predict how ECRH microwave beams broaden in turbulent edge plasma of fusion devices, validated against numerical simulations, highlighting significant beam broadening at ITER conditions.

Contribution

The paper introduces two new analytical models for ECRH beam broadening in turbulent edge plasma, providing explicit expressions and validation against numerical simulations.

Findings

Strong spatial beam broadening predicted at ITER edge conditions

Analytical models agree with 2D Maxwell solver results

Beam diffusion effects are significant in turbulent plasma edges

Abstract

Two analytical models for the ordinary mode propagating through inhomogeneous edge plasma layer are developed. Simple analytical expressions for diffusion-like angular and spatial beam width variation are obtained and compared to time-averaged results coming from 2D Maxwell's equations solver for different turbulence k-spectra and plasma conditions. The strong spatial broadening of microwave beam is predicted by the two approaches at realistic turbulent edge parameters for ECRH experiments at ITER.