Warm bore anti-cryostat to investigate temperature profile of the SuperKEKB IR magnet coil bobbin
宗 占国, 大内 徳人, 土屋 清澄, 東 憲男, 山岡 広, 多和田 正文, 有本 靖 （KEK）
Abstract:In the SuperKEKB interaction region (IR), the final focus system for each beam consists of the superconducting quadrupole and correction magnets. These magnets are located between two beams and are required to be as close to the interaction point (IP) as possible. The magnets have strong space constraint and the superconducting wire will be placed on the bobbin with a small inner radius. The beam tubes will be kept at room temperature and the distance to the coil bobbin of LHe temperature is only about 3.5 mm. The thermal radiation from the warm tube will increase the coil temperature and limit the superconductor operation. This R&D is dedicated to investigating the influence of the thermal radiation with various multi-layer insulations on the superconductor. A vertical anti-cryostat prototype with warm bore was fabricated and MLI were applied in the evacuated narrow gap of 3.5 mm between 300 K and LHe temperature. In the previous experiments, the thermal radiation was estimated according to the temperature difference over the G10 cylinder wall, which covered the bobbin tube immersed in the LHe. Some improvements have been made so that the thermal radiation could also be estimated by the helium evaporation rate. This paper will introduce the improvements and the experiment results.