Cryogenics for Super-FRS at FAIR

Abstract The challenge of cooling down the huge cold mass up to 1100 tons (dominated by iron) to 4.5 K is addressed as one of the most important features for Super-FRS cryogenics at FAIR. For such large cold mass precooling with LN 2 is necessary due to the reason that approximately 80% of the cool down load is from 300K to 80K. The capacity of the LN 2 precooler at 80 K as well as the 4.5 K cooling power have been specified in order to reach a reasonable cooldown time of three to four weeks. In the paper we will also discuss the technical issues for Super-FRS magnet testing at CERN in terms of the limitations of the cooldown / warmup rates on magnets, interface definition, and the magnet cryostat protection against over-pressure under worst-case scenarios, i.e., quench and insulation vacuum sudden loss to air, which are the key issues for the cryogenic test facility planning and machine protection at FAIR. Meanwhile the important features of the refrigerator and the cryogenic distribution system for the Super-FRS at FAIR will be discussed.