Contributions of Electron Cyclotron Waves to Performance in Advanced Regimes on DIII-D

摘要

High-power electron cyclotron (EC) waves are used to increase performance in several Advanced Tokamak (AT) regimes on DIII-D where there is a simultaneous need for high noninductive current and high beta. In the Quiescent High-confinement mode (QH-mode), a direct measurement of the electron cyclotron current drive (ECCD) profile is made using modulation techniques, and a trapped electron mode (TEM) dominated regime with core T_(e)>T_(i) is created. In the "high q_(min)" AT scenario, ECCD provides part of the off-axis noninductive current and helps to produce a tearing stable equilibrium. In the hybrid regime, strong central current drive from EC waves and other sources increases the noninductive current fraction to approx=100percent. Surprisingly, the core safety factor remains above unity, meaning good alignment between the current drive profile and the desired plasma current profile is not necessary in this scenario.