Influence of the magnetic self-field on the formation of a cathode plasma jet in steady-state vacuum arcs

It is shown that magnetic pinching of a cathode plasma jet is initiated after various microjets have merged to form a single jet at a distance r>10³ d from the cathode (d is the diameter of the cathode microspot). The plasma jet acquires the form of a paraboloid of revolution whose surface oscillates about the equilibrium position because of the inertia of the plasma transverse motion. At this point, cooling of the jet ceases. Pis’ma Zh. Tekh. Fiz. 23, 47–53 (June 12, 1997)