Kinetic Theory of Transport Driven Current in Centrally fuelled Plasmas

TL;DR

This paper develops an analytical kinetic model to describe the transport-driven current in centrally fuelled tokamaks, extending previous collisionless simulations to include collisional effects, and predicts a significant current for ITER-like conditions.

Contribution

It provides the first-principles analytical expression for transport driven current in centrally fuelled tokamaks, incorporating collisional effects and trapped particle corrections.

Findings

Predicts about one mega-ampere of current for ITER conditions.

Extends collisionless models to collisional regimes.

Provides analytical expression based on kinetic theory.

Abstract

When a steady-state cylindrical plasma discharge is centrally fuelled, the collisionless radial electron flux is canonically coupled to an axial current. The identification and analysis of this transport driven current, previously reported in collisionless simulations [W. J. Nunan and J. M. Dawson, Phys. Rev. Lett. $\mathbf{73}$, 1628 (1994)], is addressed analytically and extended to the collisional regime by means of first-principles kinetic models. Collisionless radial transport is described with the standard quasilinear model and collisional velocity anisotropy relaxation with the Landau kinetic equation. When trapped particles corrections are taken into account, the solution of this kinetic model provides the analytical expression for the transport driven current in a centrally fuelled steady-state tokamak as a function of the thermonuclear power and discharge parameters. For ITER type discharges, with central fuelling, a current of about one mega-ampere is predicted by this first-principles analytical kinetic model.