Generalized ballooning and sheath instabilities in the divertor scrape-off layer
- Lodestar Research Corp., Boulder, CO (United States)
- FOM Institute for Plasma Physics, Nieuwegein (Netherlands)
The stability of the scrape-off-layer (SOL) in divertor tokamaks is important both because of the desire to stabilize edge localized modes (ELM`s) and to ensure a sufficient broad (i.e. turbulent) SOL so as to spread the heat load on the divertor plates. One aspect of this problem, treated in the present paper, is the SOL stability to high toroidal mode number (n) ballooning-type instabilities. Our equilibrium includes a simple model of the X-point geometry, and parallel (as well as cross-field) equilibrium variations of temperature, density and potential. The latter are computed numerically from the Braginsikii form for Ohm`s law. The high-n stability analysis includes the effects of curvature drive, parallel variation of the E x B drift frequency, and sheath boundary conditions at the divertor plate. Importantly, the equilibrium model assures consistency among the possible instability drives; i.e. the pressure weighting of the curvature, the plasma potential (E x B drift) and the conditions at the divertor plate are coupled by the equilibrium model. By using energy-principle-like integrals of the ballooning equation, the relative importance of the various destabilizing drives can be extracted and compared for different divertor equilibria. Sample numerical solutions will be presented.
- DOE Contract Number:
- FG02-88ER53263
- OSTI ID:
- 489385
- Report Number(s):
- CONF-960354-; TRN: 97:011526
- Resource Relation:
- Conference: International Sherwood fusion theory conference, Philadelphia, PA (United States), 18-20 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 1996 international Sherwood fusion theory conference; PB: 244 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effect of neutrals on scrape-off-layer and divertor stability in tokamaks
Linear and nonlinear studies of resistive-ballooning modes in a tokamak edge plasma with scrape-off layer