Voltage–Current Characteristics and Temperature Variation by DC Power Source for the YBCO Coated Conductor Under Spray Cooling Method

This paper proposes the spray cooling method in conducting the extremely low temperature cooling of the superconducting wire, and presents the results of cooling performance tests and characteristics of the spray cooling method. To that end, extremely low-temperature containers were designed and manufactured to enable the testing of immersion, conduction, and spray cooling methods. Then, a cooling performance test and dc transport current test were carried out according to individual cooling methods. The test results are outlined below for each cooling method. Similar trends were shown in the initial cooling performance and cooling maintenance performance of the existing immersion cooling method and the spray cooling method. Similar trends were also shown in voltage-current characteristics according to dc transport current. Thus, in order to observe the cooling characteristics of the spray cooling method further, additional tests were carried out to define temperature characteristics according to spray pressure, and the voltage-current characteristics based on spray duration. The test results confirmed that higher spray pressure resulted in better cooling performance, and longer refrigerant time resulted in more stable conduction of dc. Accordingly, quench voltage was detected as low.