Theory of fluxflow voltage noise in type II superconductors
Abstract
A theory for the fluxflow voltage noise in a typeII superconductor in the mixed state is developed. The interactions between the vortices are taken into account via a wavevector dependent interaction matrix. Applied to Johnson noise in a film without flux flow for a special measuring circuit, the theory predicts a suppression of the power spectrum at low frequencies. For fluxflow noise produced when a perfect vortex lattice moves in a superconducting foil or film containing a random array of independent pinning centers, the theory gives two contributions to the power spectrum: one from tranverse velocity fluctuations, which has a characteristic frequency determined by the characteristic frequency of the power spectrum of the elementary pinning force; the other from longitudinal density fluctuations, which may have a characteristic frequency determined by the elastic constants and the geometry of the measuring circuit. Both of these frequencies are much higher than experimentally observed values.
 Publication:

Ph.D. Thesis
 Pub Date:
 February 1981
 Bibcode:
 1981PhDT........81S
 Keywords:

 Flux Pinning;
 Noise Spectra;
 Superconductivity;
 Superconductors;
 Electric Potential;
 Electrical Measurement;
 LandauGinzburg Equations;
 Magnetic Fields;
 Magnetic Properties;
 Power Spectra;
 Superconducting Films;
 Electronics and Electrical Engineering