Transport, equilibrium, and stability of a toroidal edge plasma
The stability and transport of the drift resistive ballooning mode (DRBM) and its impact on the dynamics of a toroidal edge plasma is studied. The linear stability of the DRBM is calculated analytically and numerically, and is found to be unstable over a broad range of mode numbers. The nonlinear dynamics of the mode were studied using a fully linear, three dimensional finite difference code. It was found that the saturated turbulent transport was anomalously large and exhibited a large ballooning-like poloidal asymmetry. The growth and saturation of this mode occurred on the time scale t[sub B] = (c[sub s]/[radical]RL[sub n])[sup [minus]1]. Nonlinear two dimensional axisymmetric toroidal simulations of a tokamak edge and scrape off layer were performed to study the effect of this transport on the edge dynamics. Large parallel flows of order the local sound speed c[sub s] were generated on the longer time scale t[sub s] = (c[sub s]/qR)[sup [minus]1]. The stability of this [open quotes]equilibrium[close quotes] depends upon the parameter [alpha] = p[sub s]qR/aL[sub r]. For [alpha] [much lt] 1, the edge was unstable to the Stringer spin up instability. For weak magnetic pumping (H-mode), a poloidal rotation of order the poloidal sound speed ac[sub s]/qR was generated in the electron diamagnetic drift direction. For strong pumping (L-mode), the rotation opposed the ion diamagnetic drift. The impact of particle sources at various poloidal locations was also studied. For [alpha] > 1 the edge was unstable to the parallel velocity shear instability. The turbulence gave order unity fluctuation levels and was localized inside the last closed flux surface and on the inner side of the torus.
- Research Organization:
- Maryland Univ., College Park, MD (United States)
- OSTI ID:
- 7204444
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
TOROIDAL PINCH DEVICES
BALLOONING INSTABILITY
EDGE LOCALIZED MODES
NEOCLASSICAL TRANSPORT THEORY
FINITE DIFFERENCE METHOD
NONLINEAR PROBLEMS
PLASMA SCRAPE-OFF LAYER
BOUNDARY LAYERS
CALCULATION METHODS
CLOSED PLASMA DEVICES
INSTABILITY
ITERATIVE METHODS
LAYERS
NUMERICAL SOLUTION
PINCH DEVICES
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
TRANSPORT THEORY
700330* - Plasma Kinetics
Transport
& Impurities- (1992-)
700340 - Plasma Waves
Oscillations
& Instabilities- (1992-)