Flux generation and sustainment of a field reversed configuration with rotating magnetic field current drive

Abstract

A new experimental device has been constructed to study the flux build-up and sustainment of a field reversed configuration (FRC) with a rotating magnetic field (RMF). Even though complete penetration was expected from RMF theory, the RMF field was observed to penetrate only a few centimeters inside the FRC separatrix. Despite the limited penetration, significantly larger toroidal currents (40 kA) were driven than in previous experiments (∼2 kA) with the same RMF field. The high currents and lack of deep penetration allowed the axial field to be the dominant field throughout the FRC. The radially inward pondermotive force arising from axial screening currents at the FRC edge had a significant influence on energy and particle confinement, reducing convective losses to the limit of observability. With only ohmic heating, the measured low ion temperatures (2 eV) left the ions unmagnetized while the electrons (∼40 eV) were well magnetized. No destructive instability was observed for the RMF driven FRC despite the lack of a strong kinetic ion component.

A Self-Organized Plasma with Induction, Reconnection, and Injection Techniques: the SPIRIT Concept for Field Reversed Configuration Research

“…The primary solution candidates are RMF [33][34][35][66][67][68] and neutral beam injection [54,55,69,70]. In both the TCS and STX (Star Thrust Experiment) devices, long-time current drive by RMF was successfully demonstrated [36,71]. Field reversal was maintained as long as the RMF was supplied.…”

MHD Activity in an Extremely High-Beta Compact Toroid

“…At the same time, the FRTP-based formation method has been significantly improved (Slough et al, 1989;Hoffman et al, 1993;Pietrzyk et al, 1987;Pierce et al, 1995;Guo et al, 2004Asai et al, 2000;Binderbauer et al, 2010;Guo, et al, 2011). Recently initiated new formation methods include (1) counter-helicity spheromakmerging (CHSM) (Yamada et al, 1990;Ono et al, 1993;Gerhardt et al 2008), (2) rotating magnetic field (RMF) (Slough & Miller, 2000;Knight & Jones, 1990;A. Hoffman et al, 2002;Guo et al, 2007), (3) field-reversed mirror configuration (FRM) driven by neutral beam injection (NBI) (Logan et al, 1976), relativistic electron beam (REB) (Davis, 1976), and intense light ion beam (ILIB) injections (Greenly et al, 1986;Schamiloglu et.…”

“…Since the 1990's, a variety of alternative formation methods have emerged (Ono, Y et al, 1993;Gerhardt et al 2008;Slough & Miller, 2000;Knight & Jones, 1990;A. Hoffman et al, 2002;Guo et al, 2007;Logan et al, 1976;Davis, 1976;Greenly et al, 1986;Schamiloglu et.…”

Transient and quasisteady behavior with rotating magnetic field current drive

“…The Star Thrust Experiment ͑STX͒ has somewhat higher RMF antenna power; it forms FRCs that are more elongated than in previous experiments. 6 Another facility, the Translation, Confinement and Sustainment ͑TCS͒ Experiment, has recently been converted to include RMF antennas; there RMF current drive will eventually be applied to a hot FRC initially created by a field-reversed theta pinch. 7 The objective of this article is to investigate transient RMF phenomena on intermediate timescales that are associated with the ion fluid inertia.…”