ABSTRACT
Arcs are self-sustaining DC discharges, but in contrast to glow, they have a low cathode fall voltage of about 10 eV, which corresponds to the ionization potential. Arc cathodes emit electrons by intensive thermionic and field emission; these are able to provide high cathode current already close to the total discharge current. The secondary electron emission does not make major contributions in electrode kinetics of arc discharges, but are important in other discharges, especially in glow discharges. A picture of the gliding arc discharge trapped in the reverse vortex flow is shown on the cover of this book. Based on the Fowler-Nordheim formula, determine the critical value of the electric field necessary for the field electron emission and its dependence on the work function.
