Title :
Cathode processes in free burning and stabilized by axial magnetic field vacuum arcs
Author :
Chaly, Alexey M. ; Logatchev, A.A. ; Nik, Sergey M Shkol
Author_Institution :
Tavrida Electr. LTD, Moscow, Russia
fDate :
8/1/1999 12:00:00 AM
Abstract :
Collective behavior of the cathode spots (CS) has been investigated in free burning and stabilized by axial magnetic field (AMF) vacuum arcs. Experiments carried out proved previously discovered phenomenon of CS group formation in free burning arc to be a general phenomenon for a short high-current vacuum arc. The dependency of CS group size in the developed are on arc current for different contact materials has been analyzed. Application of AMF with even relatively low intensity strongly affects on cathode processes. In short arcs, it hinders formation of the CS group and consequently reduces thermal stress applied to the electrodes. It has been revealed that high current vacuum arc under the action of AMF can exist only at current densities exceeding certain minimal value that depends on AMF intensity, contact gap, and does not depend on current itself. The dependency of this minimal (or normal) current density on AMF intensity has been studied for short and long vacuum arcs. A qualitative model of the cathode spot dynamics has also been proposed
Keywords :
plasma diagnostics; plasma instability; plasma transport processes; vacuum arcs; arc current; axial magnetic field stabilised vacuum arcs; cathode processes; cathode spot dynamics; cathode spot group formation; cathode spot group size; cathode spots; collective behavior; contact gap; contact materials; current density; developed arc; free burning vacuum arcs; high current vacuum arc; long vacuum arcs; short high-current vacuum arc; short vacuum arcs; thermal stress; Anodes; Cathodes; Electrodes; Ignition; Magnetic fields; Magnetic materials; Plasmas; Surface cleaning; Thermal stresses; Vacuum arcs;
Journal_Title :
Plasma Science, IEEE Transactions on