Hybrid fluid-kinetic cylindrical equilibria with axial background magnetic field

TL;DR

This paper develops a hybrid fluid-kinetic model for cylindrical screw-pinch equilibria with axial magnetic fields, solving a set of quasilinear ODEs to explore static and sheared velocity states.

Contribution

It introduces a novel hybrid fluid-kinetic equilibrium model with a three-parameter ion distribution function and numerical solutions for static and sheared velocity equilibria.

Findings

Equilibria depend on radial coordinate and include axial magnetic field.

Electron pressure is isotropic; electron current aligns with magnetic field.

Kinetic ions exhibit non-gyrotropic pressure tensor.

Abstract

Self-consistent, one-dimensional quasineutral screw-pinch equilibria are constructed within a hybrid model that couples fluid electrons with kinetic ions governed by the Vlasov equation. The equilibria depend on the radial coordinate perpendicular to the cylindrical axis and include an axial background magnetic field. Adopting a three-parameter ion distribution function depending on the energy and the canonical momenta conjugate to the two ignorable coordinates, the problem is reduced to a set of four quasilinear ODEs which are solved numerically. Both static equilibria and equilibria with macroscopic ion sheared velocities are obtained. The pressure of the electron fluid is isotropic and the electron contribution to the current density is parallel to the magnetic field, while the kinetic ions are associated with a non-gyrotropic pressure tensor. By means of the solutions the various equilibrium quantities are calculated and the impact of the free parameters on the equilibrium characteristics is examined.