Role of kinetic instability in runaway electron avalanche and elevated critical electric fields

Abstract

The effects of kinetic whistler-wave instabilities on the runaway-electron (RE) avalanche is investigated. With parameters from DIII-D experiments, we show that RE scattering from excited whistler waves can explain several poorly understood experimental results seen in a variety of tokamaks. We find an increase of the avalanche growth rate and threshold electric field, bringing the present model much closer to observations than previous results. The excitation of kinetic instabilities and the scattering of resonant electrons are calculated self-consistently using a quasilinear model. We also explain the observed fast growth of electron cyclotron emission (ECE) signals and excitation of very low-frequency whistler modes observed in the quiescent RE experiments at DIII-D [D. A. Spong et al., submitted to Phys. Rev. Lett.]. These results indicate that by controlling the background thermal plasma temperature, the plasma wave can be excited spontaneously in tokamak disruptions and the avalanche generation of runaway electrons may be suppressed.

References in corpus (6)

• Effective Critical Electric Field for Runaway-Electron Generation
• Effect of partially-screened nuclei on fast-electron dynamics
• On the relativistic large-angle electron collision operator for runaway avalanches in plasmas
• Effect of bremsstrahlung radiation emission on fast electrons in plasmas
• Adjoint Fokker-Planck equation and runaway electron dynamics
• Quasi-linear analysis of the extraordinary electron wave destabilized by runaway electrons

Cited by in corpus (13)

• Runaway electron deconfinement in SPARC and DIII-D by a passive 3D coil
• Fast dynamics of radiofrequency emission in plasmas with runaway electrons
• The effects of kinetic instabilities on the electron cyclotron emission from runaway electrons
• Analytical nonlinear collisional dynamics of near-threshold eigenmodes
• Impact of a minority relativistic electron tail interacting with a thermal plasma containing high-atomic-number impurities
• Runaway electron synchrotron radiation in a vertically translated plasma
• Tomographic reconstruction of the runaway distribution function in TCV using multispectral synchrotron images
• Experimental and synthetic measurements of polarized synchrotron emission from runaway electrons in Alcator C-Mod
• Kinetic whistler instability in a mirror-confined plasma of a continuous ECR ion source
• Hot-tail electrons' impact on assimilation and injection penetration of D2 Shattered Pellet Injections
• The impact of fusion-born alpha particles on runaway electron dynamics in ITER disruptions
• Drift surface solver for runaway electron current dominant equilibria during the Current Quench
• Firewall effect on electron acceleration by R-waves and parallel electric fields