title: Recondensation performance of liquid helium cryostat for a 28 GHz electron cyclotron resonance ion source.
abstract: Cryostat performance is essential for the stable operation of a superconducting magnet. A closed-cycle liquid helium cryostat was adopted for use for a superconducting electron cyclotron resonance (ECR) ion source by recondensing liquid helium vapor. The goal was to maintain the liquid helium filled reservoir at a constant level without transferring any liquid helium during the normal operation of the ECR ion source. To accomplish this, Gifford-McMahon (GM) refrigerators, which have two cold heads, were installed on the top of the cryostat. The cooling power of the GM cryocooler is 1.5 W at the second stage and 50 W at the first stage. Each stage was connected to the liquid helium reservoir, a radiation shield including high-Tc current lead, and related items. Before commissioning the ECR ion source, a preliminary evaluation of the recondensation performance was carried out with the magnet in partial operation. The design of the cryostat, its fabrication, and the experimental results are reported.
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Seyong
authors.initials: S
authors.lastname: Choi
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Byoung-Seob
authors.initials: BS
authors.lastname: Lee
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Park
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Ok
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Chang Seouk
authors.initials: CS
authors.lastname: Shin
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Jang-Hee
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Busan Center, Korea Basic Science Institute, Busan 609-735, South Korea.
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Won
authors.affiliation: Center for Ionizing Radiation, Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea.
authors.forename: Byoung-Chul
authors.initials: BC
authors.lastname: Kim