High Reliability and Availability of the Iseult/Inumac MRI Magnet Facility

A new innovative Whole Body 11.7-T MRI magnet is currently being manufactured at Alstom Belfort as part of the Iseult/Inumac project. It will be installed in 2016 in a neuroscience research center with other very-high-field MRI equipment, operating in France at CEA Saclay. The magnet has external dimensions of 5 m in diameter and 5 m in length, with a stored magnetic energy of 338 MJ. The magnet will operate at a homogeneous field level of 11.75 T within a 90-cm warm bore and at a current of 1483 A in driven mode. The external cryoplant is connected to the magnet, and it provides pressurized Helium II at 1.8 K. The magnet facility has to operate 24 h a day continuously for several years. Therefore, all external components have been designed to avoid magnet discharge as much as possible in case of failure from the mains, power supplies, liquefier, helium compressor, etc. In order to increase its reliability, the quench detection system is based on majority voting redundancy. This paper describes the redundancy of the power supplies system, the architecture of the magnet safety system, the high availability of the magnet control system, and cryogenic supply.