Test Results of Gas-Cooled Prototype Magnet for In-Flight Fragment Separator

The first quadrupole magnet at the in-flight fragment (IF) separator of heavy ion accelerator should withstand intense radiative heat load of neutron beam. Most of the HTS magnets are cooled by liquid cryogen or conduction cooling methods. However, the quadrupole magnet is exposed to the intense radiation heat load, and the quadrupole magnet can be cooled by the circulation of cold gaseous helium. The gaseous helium cooling system is composed of a liquid nitrogen precooler, a recuperator, a compressor at room temperature, and a single-stage GM cooler. Nichrome wire inside bobbin simulates the radiative heat load by neutron beam. The prototype magnet consists of two single pancake coils and has the half length of the full-scale HTS quadrupole magnet. HTS wire is wound on an aluminum bobbin without insulation layer. This paper describes the thermal stability test results of the prototype HTS magnet using additional heater to simulate the large radiation heat load. The operating current is transported while applying the additional heating on the bobbin surface, and the thermal characteristic is investigated. The experimental data will be used to design the thermal structure of the HTS magnets used in the first quadrupole magnet at the IF separator.