Contributions of Electron Cyclotron Waves to Performance in Advanced Regimes on DIII-D
Abstract
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 Te>Ti is created. In the "highqmin" 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 ≈100%. 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.
- Publication:
-
Radio Frequency Power in Plasmas
- Pub Date:
- December 2011
- DOI:
- 10.1063/1.3665023
- Bibcode:
- 2011AIPC.1406..497P
- Keywords:
-
- plasma heating;
- plasma transport processes;
- differential equations;
- optimisation;
- 52.50.Qt;
- 52.25.Fi;
- 02.30.Hq;
- 02.60.Pn;
- Plasma heating by radio-frequency fields;
- ICR ICP helicons;
- Transport properties;
- Ordinary differential equations;
- Numerical optimization