Fast flow phenomena in a toroidal plasma
- Department of Physics, University of Wisconsin---Madison, 1150 University Avenue, Madison, Wisconsin 53706 (United States)
- Department of Nuclear Engineering and Engineering Physics, University of Wisconsin---Madison, 1500 Johnson Drive, Madison, Wisconsin 53706 (United States)
The bulk fluid velocity is measured spectroscopically with 10 {mu}s time resolution in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. {bold 19}, 131 (1991)], a diagnostic capability used to study the fast flow dynamics associated with locked modes and the RFP dynamo. The phase velocity of the tearing modes and the fluid velocity accelerate between sawtooth events, reaching a maximum speed of about 20 km/s in a few ms. Both slow down at the sawtooth crash in {approx}100 {mu}s. This deceleration time scale is as calculated for the tearing modes from the action of electromagnetic torque on the magnetic islands, but is much faster than expected from the viscous torque on the bulk fluid. In the RFP, correlated fluctuations in the tearing modes and fluid velocity probably also generate current via the ``RFP dynamo,`` {l_angle}{tilde u}{times}{tilde B}{r_angle}, where {bold u} is the bulk fluid velocity. Initial data indicate a possible increase in {l_angle}{ital {tilde u}}{sub {phi}}{ital {tilde B}}{sub {ital r}}{r_angle} during sawtooth events, coincident with toroidal flux generation. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
- OSTI ID:
- 165300
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 2; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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