Zonal flows and transient dynamics of the L-H transition.
We elucidate the role of zonal flows in transient phenomena observed during L-H transition by studying a simple L-H transition model which contains the evolution of zonal flows, mean ExB flows, and the ion pressure gradient. Zonal flows are shown to trigger the L-H transition and cause time-transient behavior through the self-regulation of turbulence before a mean shearing, due to a steep pressure profile, secures a quiescent H mode. Surprisingly, this self-regulation lowers the power threshold for the ultimate transition to a quiescent H-mode state.
Kim
Eun-jin
EJ
Department of Physics, University of California-San Diego, La Jolla, California 92093-0319, USA.
Diamond
P H
PH