Thermal performance of TF coils in HT-7U under plasma disruption Original Research Article

One of the most severe events for HT-7U TF coils is the plasma disruption event. Within a short period of the plasma disruption, the case and the coils will be heated up by the eddy current and coupling loss induced by the magnetic field variation. Certain amount of the deposited heat in coil cases would be conducted to the coil bundles. In this paper, the center plasma disruption is modeled and electromagnetic field is calculated by ANSYS software. The generated heat is thus directly coupled to the transient thermal analysis with the same software. It was found when the plasma current in normal condition is 1.5 MA and the disruption time constant is 3 ms, the eddy current will heat the case up to a temperature increase of about 15 K in the middle of the inner straight leg. The heat transferred from case to the cable can warm up the helium in the CIC bundle to a temperature increase of about 0.4 K 10 s after plasma disruption. The coupling loss in the coils is evaluated based on the magnetic field variation and the coupling time constant of the CICC cable. By applying GANDALF for the stability calculation, it is shown the coupling loss due to plasma disruption can reduce the temperature margin of coil by 0.63 K.