MHD stability of the spheromak

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5949664

Marklin, G J

A variety of typical experimental spheromak equilibria are analyzed for their stability to zero-..beta.. current driven ideal MHD modes. Both internal and free boundary modes are considered. For free boundary modes the exterior region is treated as vacuum or as conducting plasma, which produces line tying. Both analytical and numerical techniques are employed, but most calculations use 2-D equilibrium and stability codes which were developed as part of this thesis. It is shown that the force-free Taylor equilibrium in cylindrical geometry is stable to internal tilting when the length is less than 1.68 times the radius. A large aspect ratio analytical model is used to show that equilibria with peaked current profiles or large flux holes are stable to free boundary kink modes when the q value on axis is greater than 1.2/n. Computer codes are used to examine free boundary modes in more general spheromak configurations. A study is made of the parametric dependencies of the n = 1 and n = 2 growth rates on the smoothness of the current profile near the separatrix, which controls the size of the flux hole and the q value on axis, the shape of the plasma surface, the position and shape of the stabilizing walls, and the effect of line tying. N = 1 tilt and shift modes are always unstable without a conducting wall. N = 2 modes are not greatly affected by plasma shape or wall position and can be stabilized by keeping the q value on axis greater than .6.

• Research Organization: Maryland Univ., College Park (USA)
• OSTI ID: 5949664
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700103 -- Fusion Energy-- Plasma Research-- Kinetics
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
ANALYTICAL SOLUTION
ASPECT RATIO
BOUNDARY CONDITIONS
CLOSED PLASMA DEVICES
HYDROMAGNETIC WAVES
INSTABILITY
PLASMA INSTABILITY
SPHEROMAK DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES