Toroidal Rotation and Core Ion Confinement with RF Heating in DIII-D

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:766933

deGrassie, J S ^[1]; Greenfield, C M; Baker, D R; Burrell, K H; Lin-Liu, Y R; Lohr, J; Luce, T C; Petty, C C; Prater, R; Staebler, G M; Heidbrink, W W; Porkolab, M

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1. General Atomics

Shear in the E x B flow velocity can stabilize turbulent transport [1], and so it is of interest to understand the physics behind electric field generation and modification in the tokamak. In DIII-D the core radial electric field in many regimes is generated by flow velocities driven by momentum input from neutral beam injection (NBI). In a variety of conditions it is observed that direct electron heating is accompanied by a reduction in the NBI driven toroidal rotation velocity, U{sub {phi}}, and the ion temperature, T{sub i}, primarily in the core, {rho} <0.5 (where {rho} is a radial coordinate of the normalized toroidal flux). This electron heating can be done with either electron cyclotron heating (ECH) or fast wave electron heating (FWEH). Both can be accompanied by the reduction in U{sub {phi}} and T{sub i} [2-4]. Details of the parallel wavenumber (k//) spectrum of the launched rf do not seem to be important in either case for the effect to exist. Reductions are observed for EC waves launched with nonzero k// for current drive or launched radially with k//=0; and for FWEH with waves directed either co or counter, using the DIII-D four strap antennas [5], This universality indicates that increased electron temperature, T{sub e}, is increasing ion momentum and thermal transport, at least in the parameter regimes of these experiments. It is also possible that nonambipolar transport of resonantly heated particles is playing a role. To date, the great majority of the DIII-D experiments have been conducted with the rf target discharges driven by co-injected NBI.

• Research Organization: General Atomics, San Diego, CA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC03-99ER54463; W-7405-ENG-48
• OSTI ID: 766933
• Report Number(s): GA-A23141
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAM INJECTION
CONFINEMENT
CURRENT-DRIVE HEATING
DOUBLET-3 DEVICE
ELECTRON TEMPERATURE
ION TEMPERATURE
ROTATION
TOROIDAL CONFIGURATION