Emission of radiation from a long Josephson junction in a thin film

Space-time nonlocal electrodynamic equations are derived for nonlinear vort ex states of a Josephson junction in a film of thickness much smaller than the London penetration depth. The spectrum and damping of generalized Swiha rt waves propagating in such a junction are analyzed. The radiation damping constant associated with the possible emission of electromagnetic radiatio n is determined in the range of Swihart wave phase velocities exceeding the speed of light. The emission of radiation from nonlinear states having dim ensions greater than the distance traversed by light in vacuum during the c haracteristic time of variation of the phase difference is investigated. It is shown that the flux density of radiation emitted by such states is loca lized in a plane orthogonal to the axis of the tunnel junction and depends weakly on the angle of observation in this plane. (C) 1999 American Institu te of Physics. [S1063-7761(99)01904-6].