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          Institute: MPI für Plasmaphysik     Collection: Articles, Books, Inbooks     Display Documents



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ID: 59836.0, MPI für Plasmaphysik / Articles, Books, Inbooks
Refrigeration system for W7-X
Authors:Bozhko, Y.; Schauer, F.
Language:English
Date of Publication (YYYY-MM-DD):2003
Title of Journal:Nuclear Fusion
Journal Abbrev.:Nucl. Fusion
Volume:43
Start Page:835
End Page:841
Copyright:Copyright © Institute of Physics and IOP Publishing Limited 2003
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The refrigeration system for the W7-X superconducting magnet and the divertor cryo-vacuum pumps is presented. In total, five main helium cooling circuits have to be supplied by the refrigerator—four for the magnet including auxiliary equipment like support structure, thermal shield and current leads, and one for the cryo-pumps. For the shields of the latter, an additional LN₂—cooling circuit is required. The lowest operating temperature is 3.3 K. It will be provided by evacuating a sub-cooler bath using a cold or warm compressor. Three of the helium cooling circuits use altogether four identical cold circulators. Apart from the current leads which are supplied with the coolant from a LHe storage tank, the peak reserve power required is equal to 7 kW at 4.5 K entropy equivalent. However, this potential maximal demand occurs continuously for periods of only a few hours at most, and altogether for less than 1% of annual time. The refrigerator thus will be designed for 5 kW continuous power at 4.5 Kequiv. corresponding to 1.5 MW compressor connected rating. The reserve peak power will be covered, if necessary, by using the latent heat and vapour enthalpy of LHe from a storage tank. This supporting LHe stream is added to the phase separator and fed subsequently to the low pressure return stream at the cold end of the cold box. LN2-pre-cooling equipment of the cold box—which is installed for W7-X cool-down anyway—can also be used to increase refrigeration power. The LHe required for maintaining reserve refrigeration power as well as for running the current leads is generally produced overnight when W7-X is in idle current mode.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Plasmaphysik/W7-X
Identifiers:DOI:10.1088/0029-5515/43/9/307
URL:http://stacks.iop.org/0029-5515/43/835
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