<title>Model of non-Josephson oscillations in the resistive state of superconducting films</title>

Abstract

A new mechanism of inelastic quasiparticle scattering in the resistive state of superconducting films (the bremsstrahlung effect) is proposed, which stimulates quantum transitions of quasiparticles (with simultaneous 'photon' emission) from the resonance level (epsilon) <SUB>1</SUB> to the edge of the superconductor energy gap (Delta) . The phase slip center (PSC) is simulated with a S-N-S contact, in which the N-layer width is d<SUB>N</SUB> equals 2(1<SUB>E</SUB>(xi) )<SUP>1/2</SUP> and the electrochemical potentials of the superconducting 'banks' are shifted (1<SUB>E</SUB> is the penetration depth of the longitudinal electric field, (xi) (T) is the coherence length). We believe, that the genesis of the level (epsilon) <SUB>1</SUB> is associated with interference effects between quasiparticles scattered by the phase boundaries. Electrons pick up the energy (epsilon) <SUB>1</SUB> in the electric PSC field due to the multiple Andreev reflection. On the NS boundary of PSC there exists nonstationary perturbation addition to the order parameter potential with amplitude (delta) approximately (Delta) (Gamma) <SUP>3/2</SUP> ((Gamma) is the depairing factor of the superconductor). In terms of model developed the non- Josephson generation effect is only possible in the case of effective overbarrier quasiparticle scattering by (delta) , when the condition (epsilon) <SUB>1</SUB> - (Delta) &gt;= (delta) is fulfilled. The generation frequency is found from the condition (epsilon) <SUB>1</SUB> - (Delta) equals $HBARw<SUB>o</SUB> on the order of (Delta) (Gamma) <SUP>3/2</SUP>. This gives the characteristic frequencies w<SUB>sn</SUB> approximately 10 MHz for tin and w<SUB>Al</SUB> approximately MHz for aluminum, which is in good agreement with experiment. The other consequences of the model proposed are discussed, which were supported experimentally.