Modeling and mechanisms of macroscopic erosion of melt layers of plasma facing components in fusion reactors
Abstract
Metallic materials such as tungsten and beryllium are candidates for the design of the plasma facing components (PFC). During plasma instabilities with short durations such as disruptions, edge-localized modes (ELM), and runaway electrons, high-power fluxes are directed to and deposited on the PFC. The thermal response of these PFC reaches melting and vaporization conditions. Considering the phenomenon of vapor shielding, both experimental and simulation results show that the material loss by vaporization is one to two orders of magnitude less than the resulting melt layer thickness [1]. Therefore, losses due to melt layer erosion and splashing can be critical erosion mechanisms and serious lifetime issues. The main mechanisms of melt layer erosion are liquid splashing due to body forces (gravity, magnetic force), momentum exchange and pressure gradient [2], which lead to the development of hydrodynamics instabilities such as Rayleigh-Taylor or Kelvin-Helmholtz instabilities [3], and boiling induced bubble formation, growth, and droplets emission [4]. The present work is to investigate in more details the physical models of these macroscopic erosion mechanisms. The numerical models are implemented based on a two-moving boundary thermal response model including the vapor-shielding effect [5]. A comprehensive understanding of these mechanisms is a key element in the design of the metallic PFC and to identify the proper operation of future fusion reactors such as ITER device.
Degree
M.S.En.E.
Advisors
Hassanein, Purdue University.
Subject Area
Nuclear engineering
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