Second Cooldown of ESS Cryogenic Distribution System Starts

CM installation
Jianqin Zhang, Cryogenics Engineer and test leader for the second cooldown, by the first medium beta elliptical cryomodule installed in the ESS superconducting linac. All images: Ulrika Hammarlund/ESS

The second phase of cooldown for the accelerator cryogenic system kicks off this week. Another step in the test and commissioning for the successful operation of the accelerator cryoplant and cryogenic distribution system.

Spoke CM

Last touches on the first installed Spoke Cryomodule, connected to the cryogenic system.

This week at ESS the Accelerator cryogenics team and in-kind partners started the second phase of testing the cryogenics for the linac. This test consists of several activities involving the accelerator cryoplant, cryogenic distribution system, and the pilot elliptical and spoke cryomodules assembly. All these components will be cooled down, operated under cryogenic conditions, and then warmed up again.

The key goal of the testing is to identify and eliminate any leaks and thermo-acoustic oscillations (unwanted acoustic vibrations) that could disrupt the  performance of the facility.

Furthermore, the tests will include the first-time operation of the two pilot cryomodules under cryogenic conditions. This step will help identify any potential hardware or control system shortcomings, ensuring that any issues are addressed before serial cryomodule installation begins.

Next steps

Following the completion of this second cooldown, ESS will start the installation of the full series of cryomodules.

Superconducting radiofrequency (SRF) cavities installed along the ESS superconducting linac (the blue part in the schematic image below) will be cooled down to an extremely low temperature (2 Kelvin), using the cryogenic distribution system.  At these temperatures, electricity is conducted without any ohmic resistance, resulting in highly efficient energy transfer.

Accelerator schematic

Linac layout

Illustration: Mamad Eshraqi/ESS

ESS cryogenics team

The cryogenic distribution system is a collaborative effort between ESS and two in-kind partners, WUST from Poland and IJCLab from France. The installation and subsequent tests are led by the ESS cryogenics team, supported by the SRF team and cryogenics controls team.

Cryo team

ESS cryogenics team in the local control room.