Observation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>H</mml:mi></mml:math>-Mode Confinement in the DIII-D Tokamak with Electron Cyclotron Heating

Abstract

The first observation of $H$-mode confinement with electron heating as the sole auxiliary heating method has been made in divertor discharges in the DIII-D tokamak. These discharges exhibit the usual characteristics of the $H$ mode, including improved confinement of particles and energy, when electron cyclotron heating is added at a power level above 0.7 MW. The $H$-mode transition is accompanied by the development of an electron temperature pedestal of 0.25 keV and a dramatic steepening of the density gradient near the separatrix.