Analysis of sudden quench of an ITER superconducting NbTi full-size short sample usingthe THELMA code

Abstract

The coupled thermal–hydraulic electromagnetic model, implemented in the THELMAcode, is applied to the analysis of the sudden quench in the ITER NbTi poloidal fieldconductor insert full-size joint sample. The computed results are compared with themeasured values, showing that the major experimental features, like the prematureand sudden voltage take-off, as well as the presence of precursors of the quenchin the form of voltage spikes, can be qualitatively reproduced by the code. Aself-consistent explanation of the phenomenon is presented, emphasising the effectof current, magnetic field and temperature non-uniformities on the cable crosssection, together with the fundamental role played by coupled electromagnetic andthermal–hydraulic dynamics in the current redistribution associated with the voltagespikes.