Lower hybrid current drive experiments on Alcator C-Mod: Comparison with theory and simulation

Journal Article · Thu May 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2904569· OSTI ID:21120372

Bonoli, P T; Ko, J; Parker, R; Schmidt, A E; Wallace, G; Wright, J C; Fiore, C L; Hubbard, A E; Irby, J; Marmar, E; Porkolab, M; Terry, D; Wolfe, S M; Wukitch, S J ^[1]; Wilson, J R; Scott, S; Valeo, E; Phillips, C K ^[2]; Harvey, R W ^[3]

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1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
3. CompX, P.O. Box 2672, Del Mar, California 92014-5672 (United States)

Lower hybrid (LH) current drive experiments have been carried out on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] using a radio-frequency system at 4.6 GHz. Up to 900 kW of LH power has been coupled and driven LH currents have been inferred from magnetic measurements by extrapolating to zero loop voltage, yielding an efficiency of n{sub e}I{sub LH}R{sub 0}/P{sub LH}{approx_equal}2.5{+-}0.2x10{sup 19} (A/W/m{sup 2}). We have simulated the LH current drive in these discharges using the combined ray tracing/three-dimensional (r,v{sub perpendicular},v{sub parallel} ) Fokker-Planck code GENRAY-CQL3D (R. W. Harvey and M. McCoy, in Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992) and found similar current drive efficiencies. The simulated profiles of current density from CQL3D, including both ohmic plus LH drive have been found to be in good agreement with the measured current density from a motional Stark effect diagnostic. Measurements of nonthermal x-ray emission confirm the presence of a significant fast electron population and the three-dimensional (r,v{sub perpendicular},v{sub parallel}) electron distribution function from CQL3D has been used in a synthetic diagnostic code to simulate the measured hard x-ray data.

• OSTI ID: 21120372
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
COMPARATIVE EVALUATIONS
CURRENT DENSITY
CURRENTS
DISTRIBUTION FUNCTIONS
ELECTRIC POTENTIAL
ELECTRONS
FOKKER-PLANCK EQUATION
HARD X RADIATION
LOWER HYBRID CURRENT DRIVE
LOWER HYBRID HEATING
PLASMA
PLASMA DENSITY
PLASMA SIMULATION
PLASMA WAVES
RADIOWAVE RADIATION
STARK EFFECT
THREE-DIMENSIONAL CALCULATIONS
X-RAY SOURCES