Magnetohydrodynamic Activity in High-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>, Currentless Plasmas in Heliotron-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>E</mml:mi></mml:math>

Abstract

Electron-cyclotron and neutral-beam heating have been used to produce currentless plasma with $〈\ensuremath{\beta}〉\ensuremath{\approx}(1\ensuremath{-}2)%$ in the Heliotron-$E$ device. For moderately peaked profiles, magnetohydrodynamic activity that peaks at the $t=1$ surface has been observed. The characteristics of the fluctuations are consistent with theoretical expectations for an $m=1$ pressure-driven instability. The magnetohydrodynamic activity is associated with particle and energy losses but has not yet been directly linked to global confinement.