Effect of macroscopic eroded debris on lifetimes of plasma-facing components during plasma instabilities

During plasma disruptions, the net power flux reaching the divertor surface due to the vapor-shielding effect is significantly reduced to <10% of the initial incident power from the scrape-off layer. Mass losses from atomic surface vaporization due to this reduced radiation power may be tolerated for the expected disruption frequency. However, mass losses due to splashing can be extremely high. This can severely limit the divertor system lifetime to only a few disruptions. Splashing is defined as mass loss in the form of macroscopic particles (MPs), i.e. droplets of liquid metals or particulates of nonmelting materials such as carbon-based materials. The MPs will interact with incoming plasma particles and with the vapor cloud above the surface. Therefore, the dynamic behavior of MPs in the vapor cloud and their influence on total erosion rate is a critically important problem. Results of self-consistent magnetohydrodynamic (MHD) calculations are obtained in which the dynamics of both vapor cloud and MP interaction are coupled with incoming plasma ions and electrons from the scrape-off layer during the disruption.