Equilibrium evolution in oscillating-field current-drive experiments
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
- Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 90095 (United States)
Oscillating-field current drive (OFCD) is a proposed method of steady-state toroidal plasma sustainment in which ac poloidal and toroidal loop voltages are applied to produce a dc plasma current. OFCD is added to standard, inductively sustained reversed-field pinch plasmas in the Madison Symmetric Torus [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)]. Equilibrium profiles and fluctuations during a single cycle are measured and analyzed for different relative phases between the two OFCD voltages and for OFCD off. For OFCD phases leading to the most added plasma current, the measured energy confinement is slightly better than that for OFCD off. By contrast, the phase of the maximum OFCD helicity-injection rate also has the maximum decay rate, which is ascribed to transport losses during discrete magnetic-fluctuation events induced by OFCD. Resistive-magnetohydrodynamic simulations of the experiments reproduce the observed phase dependence of the added current.
- OSTI ID:
- 21432225
- Journal Information:
- Physics of Plasmas, Vol. 17, Issue 8; Other Information: DOI: 10.1063/1.3461167; (c) 2010 American Institute of Physics; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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