Experimental investigation of the anode region of a free-burning atmospheric-pressure inert-gas arc. II. Intermediate current regime—multiple anode constriction

Stability of direct current transfer to thermionic cathodes: II. Numerical simulation

“…Results given in this section have been calculated for the (constant) thermal conductivity equal to 100 W m −1 K −1 and the specific heat equal to 200 J kg −1 K −1 ; these values may be assumed as characteristic for tungsten in the range of temperatures between 1000 and 3000 K. The pattern of the CVCs of different steady-state modes of current transfer to the cathode under these conditions is similar to the one shown in figure 1, except that the first axially symmetric spot mode on the cathode with an insulating lateral surface joins the diffuse mode [1,7]. means of equations (18) and (31) of appendix A in accord with table A1 of appendix A. The numerically calculated distributions of perturbations of these modes are shown in figure 3 for the state with U 0 = 12 V on the falling section of the CVC.…”

“…[14][15][16] and references therein) and diffuse, constricted and multiple-spot modes on anodes of high-pressure arc discharges (e.g. [17,18]; see also references in [19]). From the point of view of general theoretical physics, different modes on electrodes of dc gas discharges belong to the class of self-organization phenomena and their overall patterns are similar, in spite of particular physical mechanisms being quite different.…”

Understanding and modelling plasma–electrode interaction in high-pressure arc discharges: a review

“…The work [138] reported an experimental investigation of multiple anode constriction in free-burning arcs with watercooled electrodes in atmospheric-pressure argon and xenon in the intermediate current range. The multiple constriction was shown to be a result of an instability in the near-anode region rather than in the bulk plasma.…”

Formation of self-organized anode patterns in arc discharge simulations

“…This limited understanding is evidenced by the scarce scientific literature about the topic or by inconsistent or incomplete research findings. For example, the authors of the experimental investigation reported in [14] indicate that the transition among multiple anode attachment spots in the free-burning arc occurs due to the development of a thermal instability between Joule heating and gas cooling, whereas the authors of the comprehensive instability analysis in [17] and experiments reported in [16], conclude that multiple anode attachments form only when both, the electron overheating instability and the evaporation-ionization instability, are active. Furthermore, the experimental and theoretical studies in [19] show that the arc attachments on cold (passive) and hot (active) anodes are very different due to the dominance of different modes of instability; therefore, it could be expected that the instability dominating the attachment of an arc to a strongly cooled anode cannot be unambiguously identified.…”

“…Different types of pattern formation phenomena have been reported in a wide range of electrical discharges, from low-pressure -high-current vacuum arcs [4,5], to low-pressure -lowcurrent glow [6], streamer [7], and dielectric barrier (DBD) [8] discharges, to high-pressurelow-current glow [9,10,32], DBD [11,12], and arc [13] discharges, and to high-pressure -highcurrent arc discharges [14,15,16,17]. The phenomenological behaviors associated to the formation of electrode patterns are significantly different among these discharges.…”