ICEC/ICMC 2014 Conference

The cryogenic system for the 45 T Hybrid magnet of the HFML-Nijmegen

10 Jul 2014, 10:30

2h 15m

Poster presentation (105min) C-05: Cryostat technology Thu-Mo-Posters Session 3.2

Speaker

Mr Chris Wulffers (High Field Magnet laboratory, Radboud University Nijmegen)

Description

The High Field Magnet Laboratory of the Radboud University Nijmegen is developing a 45 T hybrid magnet system that comprises a 12.3T, 600 mm bore Nb3Sn/Cu CICC based superconducting outsert magnet and a 32.8 T, 22 MW resistive insert magnet of the Florida-Bitter type. The cryostat holding the CICC coil should also be able to withstand significant fault forces that may result from the interaction between the superconducting coil and the resistive insert magnet. The outsert magnet, the NbTi bus-bars and the coldest part of the Cu/BSCCO current leads are cooled by a forced flow of 4.5 K, 5 bar supercritical helium, supplied by a Linde LR140 type of refrigerator. In magnet idle mode the refrigerator supplies liquid helium for laboratory experiments. The correct settings of the helium flow are controlled by a valve box between the magnet and the refrigerator. In the valve-box the helium is pre-cooled to 4.5 K by a heat exchanger submerged in a bath of liquid helium. All stainless steel pillow-plate radiation shields of valve box, magnet cryostat, current lead cryostat and connecting cryo-lines are cooled by a forced flow of 20 bar helium to about 70 K by a single stage Stirling SPC-1 cryo-cooler. Finally the Cu heat exchanger of the warm part of the current leads is cooled with evaporating liquid nitrogen that fixes an intercept temperature of 78 K at the transition from the Cu-heat exchanger to the BSCCO section. In this paper we present the final design and features of the magnet cryostat and the cryogenic system.