Long term operation of the superconducting triplet quadrupoles with cryocoolers for BigRIPS in-flight separator at RIKEN

27th International Cryogenics Engineering Conference and International Cryogenic Materials Conference 2018

Kusaka, K.^1

RIKEN Nishina Center, Saitama, Japan^1

关键词: Cooling Capacity;    Cooling methods;    Current leads;    G-m cryocooler;    In-flight separator;    Large aperture;    Operational experience;    Thermal shields;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/502/1/012103/pdf
DOI  :  10.1088/1757-899X/502/1/012103

来源: IOP

【 摘 要 】

The BigRIPS in-flight separator and the radioactive isotope (RI) beam delivery lines in the RIKEN RIBF (Radioactive Isotope Beam Factory) project are characterized by the superconducting triplet quadrupoles (STQs) with cryocoolers. STQ magnet is a superferric quadrupole triplet with large apertures. They are cooled by liquid helium bath cooling method in a single cryostat with two cryocoolers. A Gifford-McMahon (GM)/Joule-Thomson cryocooler re-condenses evaporating helium gas in the helium vessel and a GM cryocooler cools the thermal shield and current leads by conduction. We have operated 22 STQ systems for more than ten years. Most of the cryocoolers have been continuously operated since 2006 without warm-up the magnets. We report operational experiences in the long-Term operation of the STQ systems. Cold maintenance methods of cryocoolers, degradation of cooling capacity, and, failures of compressors are discussed.