THE MAGNETIC VAPOR SHIELD (MVS) MECHANISM FOR PROTECTION OF HIGH-HEAT FLUX COMPONENTS IN HIGH-FIELD TOKAMAKS

Components subjected to high-heat fluxes in tokamaks include limiters, RF antennas, and portions of the first wall. The simple vapor shield resulting from ablated surface material under high-heat load may be enhanced by the large magnetic fields present in compact, high-field tokamak designs. The resulting Magnetic Vapor Shield (MVS) may reduce total melting and ablation of these components, but the effectiveness of MVS depends on several key criteria. We formulate these criteria and provide preliminary evidence for a reduction in component melting, etc. , under high-field tokamak conditions.