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Brookhaven National Lab (BNL) is in the process of building a 25 Tesla, 100 mm cold bore HTS solenoid for the Institute of Basic Science (IBS) in South Korea for their search for Dark Matter Axions. The magnet consists of 28 coils (in a 14 double-pancake (DP) coils configuration) with an inner diameter of 105 mm and has an outer diameter of 200 mm, wound using Second Generation (2G) High Temperature Superconductor (HTS) tape from SuperPower. Each coil is wound to size using approximately 300 m of conductor with the number of turns ranging between 620 to 630 turns. Most coils have one splice, but a few have three splices. Several voltage-taps are placed in each coil during winding. Two single pancake (SP) coils will be mated through a center interconnect (splice) to make a double pancake coil. Out of the 28 scheduled coils, 16 coils have been wound and tested at 77K in Liquid Nitrogen (LN2). The LN2 test is an important step during magnet construction as it provides a means to validate the quality and integrity of each coil. A significant variation in the critical current has been observed in the coils tested so far. This paper will present the construction and test results for the 16 coils at 77K.
*This work was carried out under a research agreement between Institute of Basic Science, Korea and Brookhaven Science Associates, LLC under contract No. IBS-NF-16-32. This work was also supported by Brookhaven Science Associates, LLC under contract No. DE-SC0012704, with the U.S. Department of Energy.
