Development of Large-Current Indirectly Cooled Radiation-Resistant Magnets

• Published in: IEEE transactions on applied superconductivity 2016-06, Vol.26 (4), p.1-4
• Main Authors: Takahashi, H., Agari, K., Hirose, E., Ieiri, M., Katoh, Y., Minakawa, M., Muto, R., Naruki, M., Noumi, H., Sato, Y., Sawada, S., Shirakabe, Y., Suzuki, Y., Takasaki, M., Tanaka, K. H., Toyoda, A., Watanabe, H., Yamanoi, Y., Saitoh, Y., Satoh, Y., Yahata, K.
• Format: Article
• Language: English
• Subjects: Buses (vehicles); Coils; Conductors; Conventional accelerator magnet; Cooling; High-intensity accelerator; High-intensity beam lines; Insulation; Magnet coils; Magnetic separation; Magnets; Microwave integrated circuits; Radiation-resistant magnet; Solders; Superconducting magnets; Temperature measurement; Water pipelines; Water pipes
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2016.2516591

This paper reports developments of indirectly cooled radiation-resistant magnet coils, which can be loaded with 2000-A dc. This current capacity is required for the most upstream magnets of a new high-momentum beam line to be constructed in the future extension of the J-PARC hadron experimental facility. Indirectly cooled coils using solid-conductor-type mineral insulation cables (MICs) and stainless-steel water pipes were adopted to achieve high radiation hardness. MICs were sandwiched by independent cooling water pipes and stacked in a casing, and the entire coil assembly was filled with solder. However, the maximum load applied to the indirectly cooled MIC coils was limited to 1000-A dc, mainly owing to a heat problem at the end parts of the coils. In pursuit of the required current capability, we have carried out load tests using a test sample of the end parts, which consists of MIC current leads and a copper bus bar connecting the MIC conductors, instead of a whole MIC coil. By improving the structure of the end parts, we have succeeded to operate the test piece stably with 2000-A dc in a vacuum.