Stability of field-reversed configurations in the large [ital s] experiment (LSX)

• Published in: Physics of fluids. B, Plasma physics Plasma physics, 1993-12, Vol.5:12
• Main Authors: Slough, J.T., Hoffman, A.L.
• Format: Article
• Language: eng ; jpn
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 700310 > Plasma Confinement-- (1992-); CLOSED PLASMA DEVICES; COMPACT TORUS; CONFINEMENT; FIELD-REVERSED THETA PINCH DEVICES; FLUID MECHANICS; HIGH-BETA PLASMA; HYDRODYNAMICS; INSTABILITY; MAGNETOHYDRODYNAMICS; MECHANICS; PINCH DEVICES; PLASMA; PLASMA CONFINEMENT; PLASMA INSTABILITY; PLASMA MACROINSTABILITIES; PROBES; STABILIZATION; THERMONUCLEAR DEVICES; TILTING INSTABILITY; TORI 700340 > Plasma Waves, Oscillations, & Instabilities-- (1992-)
• ISSN: 0899-8221; 2163-503X
• DOI: 10.1063/1.860554

Data from several diagnostics employed on the Large [ital s] Experiment (LSX) field-reversed theta pinch were analyzed to seek correlation between plasma distortions and the confinement properties of the field-reversed configurations (FRC's) formed. In particular, an array of [ital B][sub [theta]] probes was used to determine separatrix movement, which might indicate the existence of low-order modes, such as a tilt instability. No correlation between the quality of confinement and signal was observed. The parameter [ital s], equal to the average number of ion gyroradii inside the separatrix, has been postulated as a measure of FRC stability with values above 2, leading to instability and loss of confinement. However, the confinement observed in experiments conducted over a large range of [ital s] (1[lt][ital s][lt]8) appeared to correlate more with the shape of the equilibrium radial density profile produced during formation rather than [ital s]. Flatter profiles correlated with poorer confinement.