Hybrid Magnet to Reach 43 Tesla

Intense magnetic fields are a powerful research tool, and researchers expect the opportunities opened up by the hybrid magnet being built at the CNRS National Laboratory for Intense Magnetic Fields (LNCMI) in Grenoble to be vast. Current magnets at the facility operate at 36 teslas, but a new hybrid magnet there, made up of an assembly of copper alloy electromagnets and a superconductive magnet, will produce a field of 43T. Air Liquide advanced Technologies (CSA CSM) contributed to the project by supplying the cryogenics required for magnet operation.

“Air Liquide had to adapt to our environment in direct contact with the laboratory,” says Luc Ronayette, cryogenics manager for the 43 T Hybrid magnet project. “Its team started integrating the components of the liquefaction system and their interconnections more than six months before the delivery of the equipment to our site. Moreover, Air Liquide had to adapt the connections between the cold box and the compressor using fiber optics rather than electrical cables, which would have been disturbed by the electro-magnetic fields in certain rooms they cross.”

The cryogenic systems supplied by Air Liquide are crucial to the new magnet, as the addition of a superconducting magnet with no electrical resistance at low temperatures reduces the energy required to generate intense magnetic fields.

“It’s no coincidence that our HELIAL3 helium liquefier was selected by the LNCMI. It is a reliable and robust liquefier that will operate 24 hours/day, 10 months/year,” says Simon Crispel, Air Liquide advanced Technologies’ hydrogen and helium product manager.

Combined with a sub-atmospheric pumping system, the system is capable of supplying the magnet with superfluid liquid helium pressurized to 1,200 hPa at a temperature of 1.8 K. “Its performance exceeds our requirements,” says Ronayette. “The contract provided for a production capacity of 130 liters of liquid helium per hour. In the trials conducted in the first half of 2015, we reached 150 liters/h.”

Such a level of efficiency was previously unseen for this range of helium liquefiers, according to Air Liquide, and was made possible by the use of 3D turbines. Air Liquide and LNCMI engineers presented on the magnet’s cryogenic design at ICEC26-ICMC2016, and a paper is now available in open access from Physics Procedia.