Forced-cooled superconductors are viewed as a promising alternative in the development of high field superconducting magnets for future fusion devices. The high current density cabled superconductor is protected against thermal instabilities by forcing (single phase) supercritical helium through the cable.
The cryogenic cooling system for a forced-cooled superconducting magnet works as a refrigerator and a recirculator at the same time. The paper discusses the conceptual design of the cooling systems for forced-cooled superconducting magnets with the overall objective of reducing the refrigeration costs. The general conclusion of this article is that economic cooling systems must employ efficient cold pump recirculators in which the large flow demanded by the forced-cooled superconducting magnet is confined to the cold end of the refrigerating column. If the liquid helium pump efficiency is less than 40ยฐ/o, systems employing elevated temperature compressors are more economic.
Refrigerator-recirculator systems for large forced-cooled superconducting magnets
A. Be jan Nomenclature A Cp rh NTU d aleak S*gen T U l~actual WCarnot [~ dissipated A 7/ heat exchanger area specific heat at constant pressure mass flow rate number of exchanger heat transfer units refrigerator load heat leak originating at room temperature rate of entropy generation temperature room temperature overall heat transfer coefficient refrigerator power actual (irreversible) refrigerator power Camot (reversible) refrigerator power power dissipated in the cold space (mechanical, electrical) increment isentropic efficiency Fusion research and the need for strong and reliable magnetic fields justifies the interest in developing superconducting magnets employing forced-cooled superconductors. The idea of force-cooling hollow superconductors is not new. 1 The basic promise of forced-cooled superconductors is high current densities accompanied by the capability of The author is with the