Influence of direct current on performance of niobium conductor for miniature coaxial line

Abstract We have investigated the characteristics at 4.2 K and from 100 MHz to 2.3 GHz of a coaxial line containing a niobium wire which carries a direct current in addition to the high frequency current. The results can be understood in terms of flux penetration and are compared with published data relating to cold worked niobium in the mixed state.