Cryogenic Design of the 43 T LNCMI Grenoble Hybrid Magnet

Abstract

The association of two inner resistive coils (Polyhelix and Bitter) producing 34.5 T with an outer NbTi superconducting coil producing 8.5 T to obtain a 43 T hybrid magnet is a technical challenge. Accidental failure modes leading to complex electromagnetic behaviors and large transient dynamical forces should be anticipated. These considerations lead to a reinforced design and a thermo-hydraulic strategy to limit the overpressure. The cryostat has been designed with innovative thermomechanical supports sustaining the coil at 1.8 K-1200 hPa and the eddy current shield at 30 K, both being possibly overloaded by high dynamic forces in the worst accidental failure case.

43+T Grenoble hybrid magnet: Commissioning tests of the current leads and cryogenic satellite producing the pressurized superfluid He at 1.8 K

“…The design of the cryogenic infrastructure and cryostat has been already reported in [6], [7] and will only be briefly recalled here. The pressurized superfluid He at 1.8 K, 1200 hPa used to cool the superconducting magnet in its He vessel is obtained from a Claudet bath [8] located inside a cryogenic satellite, which is deported center to center to about 8 m from the magnet cryostat via a 5.5 m long cryogenic line (figure 1) in a reduced stray magnetic field region of 10 mT at maximum.…”