The size of the emitting region and the current density at the cathode

• Published in: Proceedings ISDEIV. 18th International Symposium on Discharges and Electrical Insulation in Vacuum (Cat. No.98CH36073) Vol. 1; pp. 302 - 305 vol.1
• Main Authors: Mourzakaev, A.M., Volkov, N.B.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 1998
• Subjects: Arc discharges; Cathodes; Current density; Estimation theory; Magnetic fields; Optical surface waves; Physics; Plasma density; Stimulated emission; Vacuum arcs
• ISBN: 0780339533; 9780780339538
• ISSN: 1093-2941
• DOI: 10.1109/DEIV.1998.740631

The paper presents an experimental estimate of 10/sup 7/ A/cm/sup 2/ (lower estimate) for the current density in a vacuum arc cathode spot and a theoretical estimate of 10/sup 9/ A/cm/sup 2/ (upper estimate) of this quantity. A criterion for the existence of an emission center (ecton) has been obtained which is the power flux required for an emission center to form, being a constant for a given cathode material. A hypothesis about the formation of current cells determining the internal structure of a cathode spot at the initial stage of a vacuum discharge has been put forward and discussed. It has been shown that this hypothesis does not contradict the available experimental data on the structure and dynamics of cathode spots.