Sensitivity to Error Fields in NSTX High Beta Plasmas
Authors: Jong-Kyu Park, Jonathan E. Menard, Stefan P. Gerhardt, Richard J. Buttery, Steve A. Sabbagh, Ronald E. Bell and Benoit P. LeBlanc
Abstract:
It was found that error field threshold decreases for high β in NSTX, although the density
correlation in conventional threshold scaling implies the threshold would increase since higher β
plasmas in our study have higher plasma density. This greater sensitivity to error field in higher β
plasmas is due to error field amplification by plasmas. When the effect of amplification is included
with ideal plasma response calculations, the conventional density correlation can be restored and
threshold scaling becomes more consistent with low β plasmas. However, it was also found that
the threshold can be significantly changed depending on plasma rotation. When plasma rotation
was reduced by non-resonant magnetic braking, the further increase of sensitivity to error field was
observed.
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Submitted to: Nuclear Fusion, (September 2011)
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Download PPPL-4707 (pdf 881 KB 18 pp)
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