Heat transfer analysis of force-cooled current leads in superconducting electric equipments based on finite element method

In superconducting electric equipments, the current lead connects the room-temperature power supply and the low-temperature superconducting magnet. It is the main source of thermal leakage in the system. In order to decrease the thermal leakage, it is necessary to analyze the thermal loss of current lead. The heat leakage analysis and optimization design of 35kV/2kA current lead are presented in this paper. Based on initial range of current lead acquired from traditional methods, the electric-thermal coupling analysis will be executed based on finite element method. The length and cross sectional area ratio of the current lead at minimum heat leakage condition will be got. Under the nitrogen forced cooling flow condition, the heat transfer problem of the current lead and the nitrogen is analyzed under FLOTRAN software. The temperature distribution of copper wire and nitrogen flow, heat transfer coefficient and pressure will be calculated. The results are helpful to determine the operating parameters of the vacuum pump.