Measurement of core velocity fluctuations and the dynamo in a reversed-field pinch
- Department of Physics, University of Wisconsin---Madison, 1150 University Avenue, Madison, Wisconsin 53706 (United States)
Plasma flow velocity fluctuations have been directly measured in the high-temperature magnetically confined plasma in the Madison Symmetric Torus (MST) Reversed-Field Pinch (RFP) [R. N. Dexter {ital et al.}, Fusion Technol. {bold 19}, 131 (1991)]. These measurements show that the flow velocity fluctuations are correlated with magnetic field fluctuations such that the electromotive force {l_angle}{tilde {bold v}}{times}{bold {tilde B}}{r_angle} approximately balances parallel Ohm{close_quote}s law, E{sub {parallel}}+{l_angle}{bold {tilde v}{times}{tilde B}}{r_angle}{sub {parallel}}={eta}J{sub {parallel}}. This initial measurement is subject to limitations of spatial localization and other uncertainties, but is evidence for sustainment of the RFP magnetic field configuration by the magnetohydrodynamic (MHD) dynamo, {l_angle}{bold {tilde v}{times}{tilde B}}{r_angle}. Both the flow velocity and magnetic field fluctuations are the result of global resistive MHD modes of helicity m=1, n=5{endash}10 in the core of MST. Chord-averaged flow velocity fluctuations are measured in the core of MST by recording the Doppler shift of impurity line emission with a specialized high resolution and throughput grating spectrometer. Magnetic field fluctuations are recorded with a large array of small edge pickup coils, which allows spectral decomposition into discrete modes and subsequent correlation with the velocity fluctuation data. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 344904
- Report Number(s):
- CONF-981127-; ISSN 1070-664X; TRN: 99:005500
- Journal Information:
- Physics of Plasmas, Vol. 6, Issue 5; Conference: 40. annual physics of plasmas meeting, APS Division of Plasma Physics, New Orleans, LA (United States), 16-20 Nov 1998; Other Information: PBD: May 1999
- Country of Publication:
- United States
- Language:
- English
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Measurement of core velocity fluctuations and the dynamo in a reversed-field pinch