The high temperature superconducting (HTS) magnets cooled by solid nitrogen (SN2) are of great merits of lower thermal temperature gradient, better thermal uniformity and thermal stability. However, the existing cooling system cannot provide a long-term stable low-temperature circumstance for HTS magnets due to significant heat load, since they are not specially designed for the SN2. Meantime, due to the large density and thickness of the stainless steel, which is the main constituent constructing the cryostat, the whole system is too weight to realize the compact and light-weight design of the HTS magnets. To overcome these shortcomings, we utilized two radiation shields, which are cooled by liquid nitrogen and first stage of cryocooler, to reduce the heat load of SN2 cooling system as well as to improve the working time of SN2 in this study. And we have introduced a pluggable cryocooler to reduce the whole weight of the SN2 cryostat. Afterwards, we have investigated the performance of the presented cooling system in conjunction with HTS magnets, the theoretical calculation shows that the 20 liters of SN2 can work more than 6 hours from 30K to 40K without any operating and thermal problems. The results of this work could provide a diagram for the future design and construction of high efficiency SN2 cooling system for HTS magnets.
Key words: Solid nitrogen; Cooling system; HTS magnets; Heat load