Analysis of the transient heat flux on divertor surface during plasma disruption in EAST

Abstract

Plasma disruption is one of the most dangerous events which will directly influence operation safety of future large-scale fusion devices. During the thermal quench (TQ) stage, extremely high transient heat flux up to thousands of MWm−2 (in several ms) is deposited on the surface of plasma-facing components (PFCs), which will undoubtedly cause damage, namely, roughness, cracking, and even melting of the metal wall material, seriously shortening the lifetime of the PFCs. Based on temperature evolution measurement by a high temporal and spatial resolution IR diagnostic system in combination with the thermal calculation using ANSYS, the transient heat flux on the divertor during plasma disruption was investigated in the EAST. The maximum surface temperature rise during plasma disruption can reach up to 1000 °C in the case of stored energy ∼250 kJ, and the corresponding local peak heat flux during plasma disruption calculated to be more than several hundred MWm−2 (∼ms), which is possible to induce the damage to metal PFCs. The transient heat-flux-induced cracking and melting phenomena on the dome and baffle plates of the divertor, also illustrate that the local transient heat flux during plasma disruption in EAST may be significant and cannot be ignored. Moreover, the statistical analysis of plasma discharge parameters reveals that the maximum temperature rises and local transient heat flux on wall surface during the disruption phase generally increases with the increasing of energy storage in the core plasma. Thus, the EAST should pay attention to mitigating of plasma disruption in the future high parameter operations.

Keywords

• Disruption
• Transient heat load
• Divertor
• Melting
• EAST