Swihart velocity

Originally, in superconducting transmission lines, the Swihart velocity is the propagation velocity of electromagnetic waves along transmission lines.

Swihart velocity plays an important role in the physics of long Josephson junctions (LJJ) that, in essence, are superconducting transmission lines with dispersion and nonlinearity due to Josephson effect. In LJJ, Swihart velocity is a characteristic velocity of propagation of electromagnetic waves (aka Josephson plasma waves), see long Josephson junction for details. For example, the group velocity may have any value from zero up to Swihart velocity.