New Studies of the Arc Discharge

The equation V = A + B/Iⁿ which correctly represents all normal arc characteristics is used as the starting point for a general discussion of arc phenomena and industrial applications. Tests of this equation are applied to iron arcs in various gas atmospheres to obtain a series of values for A and B, making possible certain deductions about arc voltage variations and significance of the characteristics. In limiting the current exponent n, the anode temperature must exert considerable influence on the discharge as a whole. Suggestions are given why this may be so. A value of n is predicted from the arc stream geometry, and is compared with actual values of n for various arcs. From energy considerations of this equation new concepts of the ``minimum energy´´ and the ``excess energy´´ requirements in the arc conduction process are gained. Some applications to arc problems prove these concepts valuable. On this basis high temperature arcs are shown to be the most efficient. Light intensity and probe measurements on the arc stream suggest a new physical picture of high current arcs. Some difficulties are removed in accounting for energy equilibrium at the welding arc cathode.