In order achieve the HL-LHC goal of running at an levelled luminosity 5 ×1034 cm-2s-1, the cryogenic infrastructure for the cooling of the LHC magnet powering system and accelerating structures will have to be adapted and upgraded along several lines.
Specific cryogenic cooling capacity upgrades will be required for the main 400 MHz RF-cavities in IR4, functioning presently at saturated helium temperatures (4.5 K) and being cooled from the same refrigerator source as the whole 3.3 km long magnet sector they belong to. The refrigerator for sector 34 will be upgraded to compensate for the RF load, while sector 45 will profit for the reduced load from P5 triplet. WP9 also takes charge of the required studies and deployment of the cryogenic infrastructure for the cooling of the crab-cavities installed in IR1 and IR5.
The higher HL-LHC luminosities will as well lead to an increase of the thermal load on the magnets near the interaction points (IPs). At present these magnets share the cooling resources with the 3.3 km long magnet sector they belong to, a situation which cannot be maintained in the HL-LHC era. Therefore, new cryo-plants in the collision points of Point 1 and 5 of about 2-4 kW per IP need to be installed. Besides the obvious benefit of increased cryogenic power, this will allow complete separation of the cryo-infrastructures of the arc and of the triplet magnets and therefore provide operational flexibilities such as the independent cool-down and warm-up of these machine sectors. WP9 also takes charge of the required distribution system of the new cryogenic infrastructure and for its connection to the new equipment in the tunnel area.