The use of large superconducting magnets on the customer's premises as in the case of Iseult in the Neurospin laboratory or at the testing stations as in the case of JT-60SA in building 126 of CEA Saclay, and accelerating structures with superconducting cavities, on testing stations such as Supratech or on the Linear IFMIF Prototype Accelerator (LIPAc) at Rokkasho in Japan, require cryogenic systems to be installed, absorbing the powers developed at low temperatures in these pieces of equipment (static losses of cryostats and dynamic losses in radio frequency or with a variable magnetic field). These systems rely on industrial helium refrigerators (which have been until this time provided by Air Liquide), adapted and inserted into a cryodistribution architecture satisfying the specific needs of each project (temperature, flowrate, pressure, power to be extracted, etc.).
Following the design and implementation some years ago of the cryogenics in the 2 accelerator cryomodules of the SOLEIL ring, running on saturated liquid helium at 4.45 K, the latest cooling systems of this type that have been installed or will soon be installed are as follows:
- the equipment needed for superfluid helium cryogenics pressurized to 1.8 K for the Iseult magnet in the rooms and basements of the Neurospin laboratory;
- the cryogenic plant of the LIPAc associated with the cryomodule with 8 superconducting cavities at a radio frequency working at 4.45 K; SACM is responsible for the design of this supply and monitoring of its installation in Japan.
Both of these 2 projects required the adaptation of the machine's operating mode (magnet and accelerator), gas and liquid storage, the valve panels controlling the return of the fluid to ambient temperature, the valve boxes or cryogenic satellite, the helium pumping systems and the transfer lines providing cooling and continuous and reliable supply of helium to the superconducting elements. The refrigerators selected for these 2 applications develop, respectively, equivalent powers of 200 W and 300 W at 4.4 K for Iseult (already installed) and for LIPAc (in request for proposal).
Picture of the Air Liquide refrigerator installed in the basements of Neurospin with the storage of 5000 liters of liquid helium in the background.
Diagram of the cryogenic plant installed in the IFMIF-LIPAC building in Japan.
In the Iseult project, only the refrigerator and the cycle compressors (145 kW installed) have been requested of the manufacturer (Air Liquide Advanced Technologies). All other equipment was been designed and is being manufactured by SACM. In the IFMIF project, very far from our base of operations, the manufacturer who will supply the refrigerator (AL-AT or Linde Kryotechnik) will also have to construct and install the other equipment of the cryogenic station (175 kW installed) based on a design and specifications developed at Saclay.
For these different projects, we draw from the large amount of feedback and know-how of the teams working on our testing stations using these types type of cooling or liquefaction systems (4 machines are currently in service at SACM).
