Metallic melt transport across castellated tiles

Abstract

In future fusion reactors, extended melt pools in combination with strong plasma-induced accelerations, suggest that metallic melt could reach the gaps between castellated plasma-facing components, potentially accompanied by profound changes in their mechanical response. The first results of a combined experimental and modelling effort to elucidate the physics of melt transport across gaps are presented. Transient melting of specially designed tungsten samples featuring toroidal gaps has been achieved in ASDEX Upgrade providing direct evidence of gap bridging. Detailed modelling with the MEMENTO melt dynamics code is reported. Empirical evidence and simulations reveal that the presence of gaps can be safely ignored in macroscopic melt motion predictions as well as that the re-solidification limited melt spreading facilitates gap bridging and leads to poor melt attachment. The findings are discussed in the context of ITER and DEMO.

Melting of W/Cu flat type component for main limiter and its impact on plasma operation in EAST experiments

“…The presence of a liquid phase raises the possibility of significant surface profile modifications during melt events, which could degrade future power handling performance [5]. To address these concerns, extensive experimental studies have been conducted in various tokamak devices including TEXTOR [6][7][8], ASEDEX Upgrade [9][10][11][12][13], JET [14,15], DIII-D [16], WEST [17,18] and KSTAR [19] to investigate W melting behavior and its impact on plasma operations and engineering reliability. Additionally, predictive modeling using MEMENTO (formerly MEMOS-U), a state-of-the-art numeric tool exclusive to ITER, has been employed to study tungsten's thermal response and melt dynamics [20,21].…”