Electrode surface control of the transition from micro-arcs to high-current arcs in atmospheric-pressure plasmas

The role of electrode surface and, especially, the effect of work function of a composite electrode surface in the transition process from micro-arcs to big-arcs under atmospheric pressure plasma conditions have been analyzed using an arc-spot model. It is seen that the transition from microarcs to big-arcs occurs at relatively high work function values. An increase in the work function of a composite electrode surface results in arcs which carry higher currents, and have higher arc-spot temperatures. The critical arc current for the transition to this high-current big-arc mode is found to depend both on the electrode work function and on the electrode temperature. The model can also be used to predict the arc-spot temperature for any given arc temperature value.<>