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Title: High temperature superconducting current leads for fusion magnet systems

Superconducting magnets for fusion applications typically have very high operating currents. These currents are transmitted from the room temperature power supplies to the low temperature superconducting coils by way of helium-vapor-cooled current leads. Because of the high current magnitude and the resistive characteristics associated with the normal metallic lead conductors, a substantial amount of power is dissipated in the lead. To maintain a stable operation, a high rate of helium vapor flow, generated by the boil-off of liquid helium, is required to cool the lead conductors. This helium boil-off substantially increases both the installation capacity and the operating cost of the helium refrigerator/liquefier. The boil-off of liquid helium can be significantly reduced by employing ceramic high temperature superconductors, such as Y-Ba-Cu-O, in the low temperature part of the lead conductor structure. This concept utilizes the superconducting, as well as the low thermal conductivity properties of the superconductor materials in eliminating power dissipation in part of the current lead and in inhibiting heat conduction into the liquid helium pool, resulting in reduced helium boil-off. This design concept has been conclusively demonstrated by a 2-kA current lead test model using Y-Ba-Cu-O (123) material which, although not optimized in design, has significantly reducedmore » the rate of helium boil-off in comparison to optimized conventional leads. There appear to be no major technological barriers for scaling up this design to higher current levels for applications in fusion magnet systems or in fusion related testing activities. The theoretical basis of the current lead concept, as well as the important design and technology issues are addressed. The potential cost saving derived from employing these leads in fusion magnets is also discussed. In addition, a design concept for a 10-kA lead is presented.« less
Authors:
; ;  [1] ;  [2]
  1. (Westinghouse Electric Corp., Pittsburgh, PA (United States). Science and Technology Center)
  2. (Argonne National Lab., IL (United States))
Publication Date:
OSTI Identifier:
6129358
Report Number(s):
ANL/CP-74429; CONF-910968--21
ON: DE92001927
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: 14. IEEE symposium on fusion engineering, San Diego, CA (United States), 30 Sep - 3 Oct 1991
Research Org:
Argonne National Lab., IL (United States)
Sponsoring Org:
DOE; USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Ma; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; SUPERCONDUCTING WIRES; HIGH-TC SUPERCONDUCTORS; THERMONUCLEAR REACTORS; COST; CRYOGENICS; DESIGN; HELIUM; POWER SUPPLIES; SUPERCONDUCTING MAGNETS; YTTRIUM COMPOUNDS; ELECTRICAL EQUIPMENT; ELECTROMAGNETS; ELECTRONIC EQUIPMENT; ELEMENTS; EQUIPMENT; FLUIDS; GASES; MAGNETS; NONMETALS; RARE GASES; SUPERCONDUCTING DEVICES; SUPERCONDUCTORS; TRANSITION ELEMENT COMPOUNDS; WIRES 700480* -- Fusion Technology-- Component Development; Materials Studies-- (1992-); 665411 -- Basic Superconductivity Studies-- (1992-); 360207 -- Ceramics, Cermets, & Refractories-- Superconducting Properties-- (1992-)