THE A.C. RESISTANCE OF NON-IDEAL SUPERCONDUCTORS,
Abstract
A direct electrical measurement is made of the resistance of non-ideal superconductors at power and audio frequencies, at 4.2 K and in zero applied field. The resistance of short samples of several Nb-Zr and Mo-Re alloys is found to be independent of the composition and of impressed current. The resistivity is found to depend on f(0.5) above 1000 cps and on f(1.7) at f below 500 cps. The resistance is also independent of wire diameter for a certain range of sizes in the vicinity of 10 mil. Three explanations are considered to see if they could account for resistance at low frequencies. Relaxation time effects are ruled out by measurements at high frequencies. Inductive coupling between the magnetic fields of the normal and the supercon ducting currents leads to a resistance effect six orders of magnitude lower than the observed ones, and an f(2.0) dependence. Trapping of flux with in the superconductor is considered and it leads to an upper bound for the resistance that agrees with the experimental results in being inde pendent of the wire diameter and the current, and giving the approximately correct resistance values, although an f(1.0) dependence. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1963
- Accession Number
- AD0418533
Entities
People
- Jacob L. Zar