Computational study on eddy current characteristics in a super conducting tokamak

Eddy currents in a super conducting (SC) tokamak were calculated in order to understand the characteristics of magnetic fields, electromagnetic (EM) forces and joule heat generations due to those currents. The SC tokamak with plasma current of 10 MA and an elongated shaped plasma with a major radius of 4.8 m was taken for the study. The characteristics other than those on the vacuum vessel (VV) were studied. The magnetic fields due to eddy currents on the cryostat as well as the VV could not be ignored. The cryostat eddy current produced a 5×10−3 T vertical field. The EM force on the cryostat was on the order of 10 kPa, much less than atmospheric pressure. The TFC structures experienced joule heat of 2.2 MJ due to eddy currents in a normal discharge, but 10 times more joule heat was calculated in a disruption. A large amount of joule heat generation was calculated in the case of TFC SC quench, which would halt running of experiments for several days.