Validation and Performance of the LHC Cryogenic System Through Commissioning of the First Sector

Abstract

The cryogenic system [1] for the Large Hadron Collider accelerator is presently in its final phase of commissioning at nominal operating conditions. The refrigeration capacity for the LHC is produced using eight large cryogenic plants and eight 1.8 K refrigeration units installed on five cryogenic islands. Machine cryogenic equipment is installed in a 26.7-km circumference ring deep underground tunnel and are maintained at their nominal operating conditions via a distribution system consisting of transfer lines, cold interconnection boxes at each cryogenic island and a cryogenic distribution line.The functional analysis of the whole system during all operating conditions was established and validated during the first sector commissioning in order to maximize the system availability. Analysis, operating modes, main failure scenarios, results and performance of the cryogenic system are presented. ABSTRACTThe cryogenic system [1] for the Large Hadron Collider accelerator is presently in its final phase of commissioning at nominal operating conditions. The refrigeration capacity for the LHC is produced using eight large cryogenic plants and eight 1.8 K refrigeration units installed on five cryogenic islands. Machine cryogenic equipment is installed in a 26.7-km circumference ring deep underground tunnel and are maintained at their nominal operating conditions via a distribution system consisting of transfer lines, cold interconnection boxes at each cryogenic island and a cryogenic distribution line.The functional analysis of the whole system during all operating conditions was established and validated during the first sector commissioning in order to maximize the system availability. Analysis, operating modes, main failure scenarios, results and performance of the cryogenic system are presented.

Design, Production and First Commissioning Results of the Electrical Feedboxes of the LHC

“…Starting from April 2007, the DFBs of sector 7-8 of the LHC have been cooled and their circuits progressively powered [9][10]. One of the first tasks during the commissioning was to verify the liquid helium levels in the DFBs and the correct cryogenic operation.…”

Commissioning of the Cryogenic Transfer Line for the Katrin Experiment

“…A value of 0.2 W/m was reported in [9] for the 1.9 K circuit in the cryogenic distribution system of the LHC. 9 The value relates to the transfer line length, not to each process line F and G.…”

“…With a total length of 20 m between the coldbox and the WGTS valve box, a specific thermal loss of 0.35 ± 0.10 W/m was measured in the WGTS beam tube cooling circuit 9 , with passive lines A, C and D. This heat leak will be lower during standard operation, being then distributed to both the beam tube and the magnet cooling circuit, while the sum for both circuits will increase.…”

First assessment of reliability data for the LHC accelerator and detector cryogenic system components

“…This means that important reliability issues become rapidly common knowledge amongst users as well as suppliers. In the past there have been only a few initiatives to collect systematic reliability data for cryogenic installations, and the number of reliability reports from individual installations is limited [7][8][9][10][11][12][13][14][15]. This might be explained by the fact that most laboratories will only dispose of one or very few cryogenic installations and do therefore not have sufficient hindsight.…”