On the second harmonic electron cyclotron resonance heating and current drive experiments on T-10 and DIII-D
- General Atomics, San Diego, CA (United States)
- Kurchatov Inst., Moscow (Russian Federation). Russian Research Center
- Inst. of Applied Physics, Nizhny Novgorod, (Russian Federation)
Studies of electron cyclotron current drive at the second harmonic resonance have been performed both on the DIII-D and T-10 tokamaks at injected power levels of approximately 0.5 MW. The DIII-D experiment used high held launch of the extraordinary mode at an angle of 15{degree} to the radial. In this experiment, with pulse lengths {approx_equal} 500 msec, a loop voltage difference, compared to the value expected from the measured profiles, of {approx_equal} 50 mV was ascribed to approximately 50 kA of rf-driven current. When dc electric field and trapped particle effects were considered, this was consistent with theoretical predictions. T-10 experiments planned for the fall of 1992 will use low field launch of the extraordinary mode and an injection angle of 21{degree} off-radial. In preliminary experiments with relatively poor machine conditions and pulse lengths {approx_equal} 400 msec, rf current drive was not observed despite the fact that driven currents as low as 10 kA, corresponding to a loop voltage difference for co- versus counter-injection of 20 mV, could have been detected. In this paper we examine the T-10 experiments using ray tracing and transport calculations in an attempt to understand the results. The dependence of the current drive efficiency on discharge parameters, flux penetration, and non-linear effects will be discussed. The results show that the launching geometry can have a significant effect on the observation of electron cyclotron current drive using the loop voltage as a diagnostic. In addition, predictions for the next series of experiments on T-10, for which greater than 2 MW of high frequency power should be available, will be presented.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114; W-7405-ENG-48
- OSTI ID:
- 10135846
- Report Number(s):
- GA-A-21107; CONF-9210300-2; ON: DE93008987
- Resource Relation:
- Conference: EC 8. joint workshop on electron cyclotron emission and electron cyclotron heating,Gut Ising (Germany),19-21 Oct 1992; Other Information: PBD: Feb 1993
- Country of Publication:
- United States
- Language:
- English
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