Phase-slip centers in long superconducting filaments

The behavior of phase slip centers and their interactions via exchange of ac and dc quasiparticles in long superconducting filaments are studied with samples fabricated by using an electron beam lithography technique. The data show that the ac decay length of quasiparticles is shorter than the dc decay length in indium at temperatures near T _c . The interactions among phase slip centers in the long filament are interpreted on the basis of critical current variations due to quasiparticle exchange, from which a dc decay length Λ≈5.0 μm for indium at T/T _c =0.992 has been obtained. The results indicate that a phase slip center can be used as a quasiparticle detector to obtain information about other phase slip centers and their mutual interactions.