CURRENT-DRIVEN PLASMA INSTABILITIES IN SUPERCONDUCTING SYSTEMS

Experimental evidence is presented for the existence of a current-driv en plasma instability in superconducting films. Anomalous dissipation has been observed in a current-carrying superconducting YBa2Cu3O7 micr obridge film which is separated from a superconducting tin film by an insulating spacer layer. This is consistent with the instability predi cted for a system of two superconductors separated by an ideal interfa ce and carrying oppositely directed currents. New calculations show th at in spite of the presence of the insulting layer, the instability sh ould still occur due to proximity effects.