Lambda Front Propagation in the Superfluid Helium Contained in the External Auxiliary Bus-Bar Line of the LHC
Journal Article
·
· AIP Conference Proceedings
- CERN, European Organization for Nuclear Research, 1211 Geneva 23 (Switzerland)
The array of the corrector magnets of the LHC arc, associated with the main and some dispersion suppressor quadrupoles are powered by a special line routed inside the cryostat, running alongside the cold mass of the half-cell. This line, composed of a 50 mm diameter stainless steel tube fixed to the cold mass, houses the superconducting multi-wire cable(s) carrying the 600 A and 6 kA current to the corrector magnets and special quadrupoles. It is cooled down to 1.9 K with pressurized superfluid helium provided by links to the cold-mass placed at regular intervals (one half-cell).The paper is focused on the process of sub-cooling the long channel from 4.5 K down to 1.9 K, including the propagation of the lambda front along the pipeline. The mechanism of sub-cooling is based on a zone of phase transformation traveling along the channel, with the heat transport both in helium and in the copper wires. A new 2-D model, including the radial heat exchange between copper and He II, has been used to study the process. A clamped temperature problem with a jump-like variable section of the channel has been solved. The model has been applied to the analysis of recovery of the line after a quench in the main magnets. A comparison with the measurements in the LHC prototype cell (String 2) is shown.
- OSTI ID:
- 20653136
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 710; ISSN APCPCS; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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