Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X

Abstract Radial profiles of density fluctuations and the radial electric field, E r , have been measured using Doppler reflectometry during post-pellet enhanced confinement phase achieved, under different heating power levels magnetic configurations, 2018 W7-X experimental campaign. A pronounced -well is with local values as high ?40 kV m ?1 in range ? ? 0.7–0.8 phase. The maximum intensity scales both plasma electron cyclotron level, following a similar trend to energy content. good agreement found when are compared simulations carried out neoclassical codes, drift kinetic equation solver (DKES) orbit-averaging for stellarators (KNOSOS). fluctuation level decreases from edge toward core drop more than reference gas-fuelled plasmas. Besides, phase, lower iota configuration standard one. To determine whether this difference related differences or stability properties two gyrokinetic codes stella EUTERPE. simulation results point profile evolution after pellet injection stabilization effect field dominant players turbulence.