Notched velocity profiles and the radial electric field in high ion temperature plasmas in the Tokamak Fusion Test Reactor

Journal Article · Sun Mar 01 00:00:00 EST 1998 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.872771· OSTI ID:580342

Ernst, D R ^[1]; Bell, M G; Bell, R E; Bush, C E; Chang, Z; Fredrickson, E; Grisham, L R; Hill, K W; Jassby, D L; Mansfield, D K; McCune, D C; Park, H K; Ramsey, A T; Scott, S D; Strachan, J D; Synakowski, E J; Taylor, G; Thompson, M; Wieland, R M ^[2]

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1. Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)
2. Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

A large {open_quotes}notch,{close_quotes} or non-monotonic feature, appears in measured toroidal velocity profiles of the carbon impurity in the Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Fusion {bold 26}, 11 (1984)], centered near the radius of strongest ion temperature gradient. This is explained as a consequence of radial momentum transport dominated by anomalous diffusion together with parallel heat friction on the impurity ions arising from the hydrogenic neoclassical parallel heat flow. The toroidal velocity profile of the hydrogenic species is predicted to be monotonic, from measurements of the impurity toroidal velocity, consistent with the anomalous radial diffusion of toroidal momentum. This supports a neoclassical calculation of the radial electric field for near-balanced beam injection. In supershot plasmas [Phys. Rev. Lett. {bold 58}, 1004 (1987)], a well structure in the radial electric field profile is found in the enhanced confinement region. An associated shear layer separates the core, where the local confinement trends are favorable, from the degraded outer region. This provides a mechanism for the nonlinear coupling of the ion temperature gradient, ion thermal confinement, and the radial electric field, which may help explain the favorable core confinement trends of very high temperature supershot plasmas. {copyright} {ital 1998 American Institute of Physics.}

• OSTI ID: 580342
• Journal Information: Physics of Plasmas, Vol. 5, Issue 3; Other Information: PBD: Mar 1998
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION
TFTR TOKAMAK
VELOCITY
ELECTRIC FIELDS
DIFFUSION
CHARGED-PARTICLE TRANSPORT
ION TEMPERATURE
PLASMA CONFINEMENT
PLASMA IMPURITIES