Accession Number : AD0710957

Title :   CRITICAL CURRENT ENHANCEMENT IN SUPERCONDUCTING LEAD SAMPLES OF VARYING CROSS SECTION.

Descriptive Note : Technical rept.,

Corporate Author : ARMY ELECTRONICS COMMAND FORT MONMOUTH N J

Personal Author(s) : Winter,J. J. ; Breslin,J. T. ; Leupold,H. A.

Report Date : JUL 1970

Pagination or Media Count : 40

Abstract : It is found that the superconducting critical currents of lead samples of a certain shape are frequently far below the values one would expect from the application of Silsbee's rule ((H sub c)(G) = (I sub c) (A)/5r(cm)). Values as low as 20%-25% of those expected are typical. By various mechanical and chemical treatments of the surface and through use of certain solders, these degraded critical currents can be greatly restored, sometimes even to their full expected value. The trapping of magnetic flux in a specimen is also capable of enhancing its resistance-free current capacity either partially or fully; the degree of enhancement depending in samples that trap appreciable amounts of flux, it is shown that its maintenance requires only negligible amounts. Infrequently, samples are encountered in which enhancement may also be attained merely by exposure to sufficiently high transport currents. (Author)

Descriptors :   (*SUPERCONDUCTORS, LEAD(METAL)), (*LEAD(METAL), ELECTRIC CURRENTS), MANUFACTURING, MAGNETIC FIELDS, HYSTERISIS

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE