Driven resonant current amplification in self-organized plasma configurations with uniform λ and plasma pressure confinement

Abstract

Driven resonant current amplification in uniform λ=μoJB, self-organized plasma configurations with plasma pressure confinement is studied. This work extends previous analyses of force-free states (J∥B) to equilibria with plasma pressure gradients (∇P=J×B≠0). An analytical treatment shows that in equilibria with uniform λ and a plasma pressure gradient that varies linearly with poloidal magnetic flux, driven resonances are either downshifted or upshifted from their force-free values. Additionally, a modification of off resonance current amplification is observed in pressure confining equilibria. Computational results add support to analytical predictions, and also include driven resonance behavior with equilibrium profiles not considered analytically. These results suggest not only persistence, but also modification of driven resonant current amplification in sustained spheromak configurations with plasma pressure confinement when compared to force-free states. By providing a basis for the existence of driven, high current amplification, pressure confining equilibria, this work provides insight into the accessibility of sustained spheromak states of most interest for potential fusion energy applications.

Effect of injected flux and current temporal phasing on self-organization in the HIT-SI3 experiment

“…The remaining three cases all solve for the state where one of the individual injectors has unit flux, and the remaining injectors plus the axisymmetric flux in the confinement volume are all zero. The purely non-axisymmetric structure of these injector states ensures that they do not couple to the axisymmetric eigenstate, as with symmetric vacuum fields, 20,21 allowing these states to be combined with k given by the lowest eigenvalue. Linear combinations of these four equilibria, possible by the use of the same eigenvalue k, allow for approximations of the 3D structure of full equilibria, including injector perturbations, to be considered.…”