Magnetic field structure in a finite-. beta. , toroidal plasma. [TERP II]

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5965725

Weber, B V

Toroidal plasmas with finite ..beta.. are produced in the TERP II device using fast rising applied fields. The formation and equilibrium phases are diagnosed using magnetic field probes. During formation, the plasma is rapidly heated by diamagnetic plasma currents. The diamagnetism decreases rapidly in the first few ..mu..sec due to an outward radial drift of the magnetic well. The loss of diamagnetism is attributed to the observed decrease and reversal of the toroidal current. The current decrease removes the inward I x B/sub z/ force necessary for radial force balance. The toroidal current behavior seems to be caused by coupling between the toroidal field coils and the plasma current. Several coupling mechanisms are examined, including anisotropic resistivity and plasma velocity. The observed current decrease can be explained by a resistive MHD model with enhanced resistivity and nearly force-free currents. Current reversal may be a toroidal effect caused by changing major and minor plasma radii. Current density in the reverse direction is seen inside the major radius during the formation. This reverse current is unstable and is lost to the chamber walls in about 10 ..mu.. sec. The forward current shows vertical motion but is confined in the outer half of the chamber. These observations agree with measurements of electron density. The current reversal phenomenon contributes to the observed rapid energy loss, limiting the ..beta.. value in the subsequent equilibrium phase, which lasts about 100 /sup +/sec.

• Research Organization: Maryland Univ., College Park (USA)
• OSTI ID: 5965725
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
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Heating
& Production
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BETA RATIO
CLOSED PLASMA DEVICES
COUPLING
CURRENT DENSITY
CURRENTS
DIAMAGNETISM
ELECTRIC CURRENTS
ENERGY LOSSES
LOSSES
MAGNETISM
PLASMA PRODUCTION
THERMONUCLEAR DEVICES
TOKAMAK DEVICES