Electron current drive by fusion-product-excited lower hybrid drift instability

TL;DR

This paper demonstrates through first principles simulations how fusion-born ions can directly transfer energy to electrons, generating current via lower hybrid drift instabilities, a key step in alpha channelling for tokamaks.

Contribution

First simulation showing collisionless energy transfer from fusion ions to electrons via lower hybrid drift instability in a realistic plasma model.

Findings

Fusion-born ions excite lower hybrid range waves.

Electromagnetic waves induce electron Landau damping.

Resulting electron tail carries a net current.

Abstract

We present first principles simulations of the direct collisionless coupling of the free energy of fusion-born ions into electron current in a magnetically confined fusion plasma. These simulations demonstrate, for the first time, a key building block of some "alpha channelling" scenarios for tokamak experiments. A fully self-consistent electromagnetic 1D3V particle-in-cell code is used to evolve a parallel drifting ring-beam distribution of 3MeV protons in a 10keV thermal deuterium-electron plasma with realistic mass ratio. Collective instability gives rise to electromagnetic field activity in the lower hybrid range of frequencies. These spontaneously excited obliquely propagating waves undergo Landau damping on resonant electrons, drawing out an asymmetric tail in the distribution of electron parallel velocities, which carries a current.