Electron Currents in Field Reversed Mirror Dynamics--Theory and Hybrid Simulation

The role of electron currents in Field-Reversed Mirror (FRM) dynamics has been studied through both analytic and computational means. In particular, the effects of electron currents near a magnetic field null is closely examined. Since the electrons are not tied to field lines in this region, they are able to partially cancel the ion current there in response to an inductive electric field and ion drag. Past workers, using a fluid description, have suggested that this cancellation may be virtually complete, making impossible the steady state operation of the FRM as well as its start-up by neutral-beam injection. However, the fluid approximation is invalid near a field null. We have developed a detailed non-fluid model for the bulk dynamics of the electrons in this region. The region is treated as unmagnetized; electrons are accelerated by the inductive electric field and collisions with ions; damping is provided by viscosity due to adjacent "fluid" electrons and scattering on the ions. The resulting equation of motion when combined with Faraday's Law predicts that, due to viscosity, current cancellation is far from complete, although electron currents near the null may slow the attempt to reverse the field via neutral-beam injection by a factor of five or so.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Stark, Robert Armand

• Physics, Fluid and Plasma

Language dc:language

eng

Identifier

(UMI)AAI8803211

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/77417