INITIATION OF MELTING AND EVAPORATING OF MATERIALS UNDER PLASMA DISRUPTION

In a tokamak reactor, a pulsed high heat flux, whose heat flux should result in up to 2x10(5)MW/m(2), would be injected to the plasma facing components (PFCs) due to a plasma disruption. By this heat load the P FCs are melted, evaporated and cracked. In this study melting and evap oration behavior was investigated through performing the experiment wi th use of an electron beam to simulate heat loads due to plasma disrup tions and tile numerical and approximate analyses. Experimental and an alytical results show that the evaporated mass increases abruptly at a curtain heat flux and time, and that the thickness of melting layer h as the maximum at a curtain heat flux. From dimensionless expressions of such results the simple dimensionless correlations between the rele vant values were obtained to estimate the significant characteristics such as evaporation thresholds and maximum melting layer thickness. Ap plying them to evaluation of the thermal resistance of materials again st various heat loads due to a plasma disruption confirms that against the milder heat load, the materials whose initiation of melting and e vaporation occurs late, such as tungsten, are suitable for armor mater ials and against the severer heat load, the materials that have a larg e of latent heat evaporation, such as graphite, are suitable for armor materials.