Heat load measurements on the JET first wall during disruptions

Abstract

Disruptions in tokamaks lead to high heat loads onto the plasma facing components (PFC). Two processes, of particular concern for the first wall integrity, have been studied in dedicated experiments at JET: (1) During the thermal quench, it is measured (using fast IR thermography) that 5% of the plasma stored energy is deposited onto the outer and inner poloidal limiters. More surprisingly, during the current quench, about 10% of the magnetic energy is deposited onto the outer and inner poloidal limiters via plasma wall interaction. (2) Very localised heat loads due to runaway electrons, generated in disruptions triggered by massive injection of argon and neon, are measured onto the JET upper dump plate. The temperature increase measured on the CFC tiles scales with the square of the runaway current.