Measurement of core velocity fluctuations and the dynamo in a reversed-field pinch

D. J. Den Hartog, J. T. Chapman, D. Craig, G. Fiksel, P. W. Fontana, S. C. Prager, J. S. Sarff

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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 et al., Fusion Technol. 19, 131 (1991)]. These measurements show that the flow velocity fluctuations are correlated with magnetic field fluctuations such that the electromotive force 〈ṽ ×B̃〉 approximately balances parallel Ohm's law, E+〈ṽ×B̃〉=ηJ . 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, 〈ṽ×B̃〉. Both the flow velocity and magnetic field fluctuations are the result of global resistive MHD modes of helicity m=1, n=5-10 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.

Original languageEnglish (US)
Pages (from-to)1813-1821
Number of pages9
JournalPhysics of Plasmas
Issue number5 I
StatePublished - May 1999

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


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