First total cooldown of the SPIRAL2 superconducting LINAC

The first total cooldown of the SPIRAL2 linear accelerator has been achieved in November, 2017 at GANIL.

Liquid helium was injected in all the cryomodules of the accelerating cavities and 16 of the 19 cryomodules met the pressure stability requirements for a significant duration.

Measurements of the helium bath pressure in the type A (left) and B (right) cryomodules.
Technical requirements ±5 mbar have been respected for all the cryomodules, and for a significant duration for 16 of the 19 cryomodules.

In parallel the pumping system was deployed to reach the required vacuum level, with a pressure consistent with beam requirements (below 10-8 mbar). Until next spring, upgrades of the cryogenic system will be performed in order to improve the pressure stability performances as well as the reliability of the system.

The SPIRAL 2 LINAC is based on superconducting, independently phased resonating cavities. The cryogenic system is crucial to achieve the superconducting state and stable operation conditions are required to insure the accelerating performances.