Cooling Strings of Superconducting Devices Below 2 K: The Helium II Bayonet Heat Exchanger
High-energy particle accelerators and colliders contain long strings of superconducting devices — acceleration RF cavities and magnets — operating at high field, which may require cooling in helium II below 2 K. In order to maintain adequate operating conditions, the applied or generated heat loads must be extracted and transported with minimum temperature difference. Conventional cooling schemes based on conductive or convective heat transport in pressurized helium II very soon reach their intrinsic limits of thermal impedance over extended lengths. We present the concept of helium II bayonet heat exchanger, which has been developed at CERN for the magnet cooling scheme of the Large Hadron Collider (LHC), and describe its specific advantages as a slim, quasi-isothermal heat sink. Experimental results obtained on several test set-ups and a prototype magnet string have permitted to validate its performance and sizing rules, for transporting linear heat loads in the W. m”1 range over distances of several tens of meters.
KeywordsHeat Exchanger Large Hadron Collider Heat Exchanger Tube Superfluid Helium Corrugate Tube
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- 1.Ph. Lebrun, Cryogenic systems for accelerators, in: “Frontiers in Accelerator Technology”, S.I. Kurokawa, M. Month and S. Turner, editors, World Scientific, Singapore (1996), pp. 681–700.Google Scholar
- 2.Ph. Lebrun, Superfluid helium as a technical coolant, in: “Atti XV Congresso Nazionale sulla Trasmissione del Calore”, Edizioni ETS, Politecnico di Torino (1997), pp. 61–77.Google Scholar
- 4.L.R. Evans, The Large Hadron Collider project, in: “Proceedings of ICEC16/ICMC Kitakyushu”, T. Haruyama, T. Mitsui and K. Yamafuji, editors, Elsevier Science, Oxford (1997), pp. 45–52.Google Scholar
- 10.B. Flemsaeter, “Contribution to the Dynamic Analysis and Optimal Control of the Superfluid Helium Cooling Loop for the LHC Magnet String”, Thesis, NTU Trondheim, Norway (1995)Google Scholar
- 11.A. Gauthier, L. Grimaud, B. Rousset, A. Bézaguet and R. van Weelderen, Thermohydraulic behaviour of He II in stratified co-current two-phase flow, in: “Proceedings of ICEC16/ICMC Kitakyushu”, T. Haruyama, T. Mitsui and K. Yamafuji, editors, Elsevier Science, Oxford (1997), pp. 519–522.Google Scholar
- 12.B. Rousset, A. Gauthier, L. Grimaud and R. van Weelderen, Latest developments in He II co-current two-phase flow studies, paper presented at this conference.Google Scholar
- 13.M.M. Kado, Thermal conductance measurements on the LHC helium II heat exchanger pipes, CERN Report AT/95–34 (CR) (1995).Google Scholar
- 14.K. Kauder, “Strömungs- und Widerstandsverhalten in Gewellten Rohren”, Thesis, Technische Universität Hannover, Germany (1971).Google Scholar
- 15.F. Déliot, private communication (1996).Google Scholar
- 16.A. Bézaguet, J. Casas-Cubillos, B. Flemsaeter, B. Gaillard-Grenadier, Th. Goiffon, H. Guinaudeau, Ph. Lebrun, M. Marquet, L. Serio, A. Suraci, L. Tavian and R. van Weelderen, The superfluid helium system for the LHC Test String, design, construction and first operation, in: “Advances in Cryogenic Engineering” Vol. 41A (1996), pp. 777–784.CrossRefGoogle Scholar
- 17.M. Chorowski, W. Erdt, Ph. Lebrun, G. Riddone, L. Serio, L. Tavian, U. Wagner and R. van Weelderen, A simplified distribution scheme for the Large Hadron Collider, paper presented at this conference.Google Scholar