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, 岩崎昌子, 山岡広, 多和田正文（KEK）

Abstract:The SuperKEKB is proposed as the upgrade project of KEKB, with the 40 times higher target luminosity. In the 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. In the cryostat the beam pipe will be kept at room temperature. The distance between the warm beam pipe and the coil bobbin 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 on the superconductor. A vertical cryostat prototype with warm bore was fabricated. Several multi-insulation layers were applied in the evacuated narrow gap of 3.5 mm between 300 K and LHe temperature and cryogenic experiments were carried out. In this paper, the configuration of the cryostat prototype will be introduced and the preliminary results will be presented.