Resistive wall modes in a reversed field pinch with interchangeable shells

• Published in: Physics of fluids. B, Plasma physics Plasma physics, 1992-04, Vol.4 (4), p.911-916
• Main Authors: Greene, Philip, Barrick, Greg, Robertson, Scott
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Magnetic confinement and equilibrium; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma interactions (nonlaser); Plasma-wall interactions; boundary layer effects; Plasma-wall interactions; boundary layer effects; plasma sheaths; Stellarators, spheromaks, compact tori, bumpy tori, and other toroidal confinement devices; Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices; Waves, oscillations, and instabilities in plasmas and intense beams
• ISSN: 0899-8221; 2163-503X
• DOI: 10.1063/1.860107

Resistive wall modes have been investigated in a reversed field pinch (Reversatron IIi [IEEE Trans. Plasma Sci. P S ‐ 1 6, 667 (1988)]) operated with three different boundary conditions: (1) a copper shell having a magnetic penetration time τ s comparable to the discharge duration, (2) a brass shell having τ s comparable to the setting‐up time, and (3) no shell, which gives τ s much shorter than the setting‐up time. The brass shell is found to impede the growth of the m=1, n=−6 ‘‘on‐axis’’ mode observed to grow in the setting‐up phase of no‐shell discharges. In the sustainment phase, there is a higher level of m=1 modes than with the copper shell and the discharge duration, ion temperature, and plasma current are reduced. The mode spectrum is broad in the sustainment phase and the degradation in discharges cannot be attributed to any single mode. There is evidence for transient mode locking resulting in a slinky mode in copper‐shell discharges.