Surface losses and self-pumping effects in a long Josephson junction - a semi-analytical approach

TL;DR

This paper develops a semi-analytical model for flux-flow dynamics in long Josephson junctions, incorporating surface losses and self-pumping effects, and validates it against numerical simulations.

Contribution

It introduces an approximate analytical solution for the modified sine-Gordon equation considering realistic effects in long Josephson junctions.

Findings

Good agreement between analytical and numerical results for current-voltage characteristics.

The model captures the impact of surface losses and self-pumping on fluxon dynamics.

Limitations of the analytical method are identified through comparison.

Abstract

The flux-flow dynamics in a long Josephson junction is studied both analytically and numerically. A realistic model of the junction is considered by taking into account a nonuniform current distribution, surface losses and self-pumping effects. An approximate analytical solution of the modified sine-Gordon equation is derived in the form of a unidirectional dense fluxon train accompanied by two oppositely directed plasma waves. Next, some macroscopic time-averaged quantities are calculated making possible to evaluate the current-voltage characteristic of the junction. The results obtained by the present method are compared with direct numerical simulations both for the current-voltage characteristics and for the loss factor modulated spatially due to the self-pumping. The comparison shows very good agreement for typical junction parameters but indicates also some limitations of the method.