Fast particle-driven ion cyclotron emission (ICE) in tokamak plasmas and the case for an ICE diagnostic in ITER

TL;DR

This paper discusses the use of ion cyclotron emission (ICE) as a passive, non-invasive diagnostic tool for fast ions in tokamak plasmas, emphasizing its potential application in ITER for monitoring fusion alpha particles and beam ions.

Contribution

It presents evidence from multiple tokamaks that ICE can effectively diagnose fast ions and supports its potential as a diagnostic in ITER's high-radiation environment.

Findings

ICE scales linearly with fusion reaction rate in JET

ICE indicates alpha-particle confinement close to classical in JET

Beam-driven ICE correlates with neutron rate drops in DIII-D

Abstract

Fast particle-driven waves in the ion cyclotron frequency range (ion cyclotron emission or ICE) have provided a valuable diagnostic of confined and escaping fast ions in many tokamaks. This is a passive, non-invasive diagnostic that would be compatible with the high radiation environment of deuterium-tritium plasmas in ITER, and could provide important information on fusion {\alpha}-particles and beam ions in that device. In JET, ICE from confined fusion products scaled linearly with fusion reaction rate over six orders of magnitude and provided evidence that {\alpha}-particle confinement was close to classical. In TFTR, ICE was observed from super-Alfv\'enic {\alpha}-particles in the plasma edge. The intensity of beam-driven ICE in DIII-D is more strongly correlated with drops in neutron rate during fishbone excitation than signals from more direct beam ion loss diagnostics. In ASDEX Upgrade ICE is produced by both super-Alfv\'enic DD fusion products and sub-Alfv\'enic deuterium beam ions.