Rapid measurement of plasma radiation power during disruption in KSTAR by thin-foil based infrared bolometer

Abstract

Plasma disruption-a sudden loss of stored energy with the formation of localized heat loads and runaway electron (RE)-can give permanent damage to the in-vessel components of the tokamak device. Presently, plasma disruption mitigation research is one of the most important issues to be studied for safe operation scenarios of future fusion generations. A dual shattered pellet injector (SPI) system is currently operating on the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak to prepare the plasma disruption mitigation scenarios for the International Thermonuclear Experimental Reactor (ITER). To evaluate the disruption mitigation efficiency of the dual SPI quantitatively, we have developed a thin-foil based infrared (IR) bolometry system. The thin-foil based infrared sensor bolometer (IRSB) is designed to absorb the broadband radiation from the plasma and measure the radiation power in the order of few milliseconds inside the extreme tokamak environment. The IRSB successively measured the radiation power during the SPI experiments on the 2020 KSTAR campaign. The details of the IRSB from the design to the installation are presented. The analytical solution of the 0-D heat transfer model in linear response regime is introduced. The linear response regime providing a practical method to calculate the radiated power from the tokamak plasma by the IRSB signal data. The 0-D and 2-D heat transfer simulations were performed to verify the analytic solution in a linear response regime.