Toroidal L and H equilibria with axisymmetric rotations

TL;DR

This paper models axisymmetric toroidal plasma equilibria with rotations, identifying L and H modes, and explores the transition as a bifurcation influenced by external heating and pellet injection, highlighting the role of edge gradients and electric fields.

Contribution

It introduces a set of solutions for toroidal equilibria with rotations, characterizing L and H modes and their transition as a bifurcation driven by external heating and pellet injection.

Findings

H mode has a steep edge gradient and large radial electric field.

L/H transition is modeled as a bifurcation between equilibrium states.

H mode is associated with improved confinement and zonal flows.

Abstract

Axisymmetric toroidal equilibria with toroidal and poloidal rotations are solved with a specific set of source functions. The two independent solutions are associated to L and H modes. The L/H transition is regarded as a bifurcation from one equilibrium configuration to another, under strong external heating and pellet injection to shape temperature and density profiles. Because of the steep edge gradient of the H solution, large static radial electric field, zonal flow, and improved confinements, come as consequences, not causes, of the H mode.