On 3 december 2018, the two-year interruption of the Large Hadron Collider LHC began at CERN in Geneva. During this time, the LHC will be shut down to revise or replace components and raise its energy level.
The newest accelerator ring at CERN, the LHC, is 27km in circumference, has 1.9K operating temperature and lies at a depth of 100m. The High Luminosity LHC (HL-LHC) is a LHC performance enhancement project designed to sustain scientific progress. As part of the HL-LHC project, the LHC refrigeration systems will experience an increase in heat loads and need to be expanded or rebuilt accordingly.
The above-mentioned conversions from 2019 till 2021 will take place in this overall context. The Linde Kryotechnik contribution is required primarily at point 4. The refrigeration system installed there in 1993 is a bottleneck due to its dual task. It cools the LHC ring section between points 3 and 4 as well as the superconducting RF cavities at point 4. The refrigeration system has already been upgraded for the LEP200 and the LHC, however a third upgrade is possible to meet the growing needs of the HL-LHC. That impresses. The upcoming conversion will increase the capacity of the refrigeration system by another 2 kW from 16.5 kW to 18.5 kW @ 4.2 K equivalent refrigerating capacity. Responsible for the increase in performance will be new, more efficient turbines whose larger dimensions require corresponding modifications to the cold boxes and adjacent accessories.
A refrigeration system, which served to cool down the Crab Cavities during operation, takes on another task for the LHC conversion time and had to be transported to point 4 accordingly. The mobile version of this refrigeration system was developed and built by Linde Kryotechnik at the request of CERN in 2016 to test the RF cavities at point 4 during the upcoming two-year conversion phase.
In Meyrin, the headquarters of CERN, another new refrigeration plants will be commissioned in 2019 for 35 g / s @ 4.2 K. Here, tests are to be carried out with new magnets, cavities and modules intended for future, stronger radiation bundles. Only then will HL-LHC be able to meet the scientific requirements by 2033.