Gyrokinetic simulation of momentum transport with residual stress from diamagnetic level velocity shears

Journal Article · Fri Apr 15 00:00:00 EDT 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3579481· OSTI ID:21537647

Waltz, R E; Staebler, G M ^[1]; Solomon, W M ^[2]

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1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
2. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)

Residual stress refers to the remaining toroidal angular momentum (TAM) flux (divided by major radius) when the shear in the equilibrium fluid toroidal velocity (and the velocity itself) vanishes. Previously [Waltz et al., Phys. Plasmas 14, 122507 (2007); errata 16, 079902 (2009)], we demonstrated with GYRO [Candy and Waltz, J. Comp. Phys. 186, 545 (2003)] gyrokinetic simulations that TAM pinching from (ion pressure gradient supported or diamagnetic level) equilibrium ExB velocity shear could provide some of the residual stress needed to support spontaneous toroidal rotation against normal diffusive loss. Here we show that diamagnetic level shear in the intrinsic drift wave velocities (or ''profile shear'' in the ion and electron density and temperature gradients) provides a comparable residual stress. The individual signed contributions of these small (rho-star level) ExB and profile velocity shear rates to the turbulence level and (rho-star squared) ion energy transport stabilization are additive if the rates are of the same sign. However because of the additive stabilization effect, the contributions to the small (rho-star cubed) residual stress is not always simply additive. If the rates differ in sign, the residual stress from one can buck out that from the other (and in some cases reduce the stabilization.) The residual stress from these diamagnetic velocity shear rates is quantified by the ratio of TAM flow to ion energy (power) flow (M/P) in a global GYRO core simulation of a ''null'' toroidal rotation DIII-D [Mahdavi and Luxon, Fusion Sci. Technol. 48, 2 (2005)] discharge by matching M/P profiles within experimental uncertainty. Comparison of global GYRO (ion and electron energy as well as particle) transport flow balance simulations of TAM transport flow in a high-rotation DIII-D L-mode quantifies and isolates the ExB shear and parallel velocity (Coriolis force) pinching components from the larger ''diffusive'' parallel velocity shear driven component and the much smaller profile shear residual stress component.

• OSTI ID: 21537647
• Journal Information: Physics of Plasmas, Vol. 18, Issue 4; Other Information: DOI: 10.1063/1.3579481; (c) 2011 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR MOMENTUM
DOUBLET-3 DEVICE
L-MODE PLASMA CONFINEMENT
PLASMA
PLASMA DIAMAGNETISM
PLASMA PRESSURE
PLASMA SIMULATION
PRESSURE GRADIENTS
RESIDUAL STRESSES
ROTATION
SHEAR
TEMPERATURE GRADIENTS
TURBULENCE
VELOCITY
WAVE PROPAGATION
CLOSED PLASMA DEVICES
CONFINEMENT
DIAMAGNETISM
MAGNETIC CONFINEMENT
MAGNETISM
MOTION
PLASMA CONFINEMENT
SIMULATION
STRESSES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES