Der Einfluß der Wärmeleitung zur Kathode im elektrischen Feldbogen

For various cathode metalsKesaev has measured the arc lifetime as a function of current. RecentlyKingdon, assuming the field emission theory could not explain these experiments, suggested that the secondary electron emission produced by positive ions through a diffusion-controlled neutralization process determines the cathode mechanism. In this paper another assumption is made, based on the field emission theory: the cathode needs a minimal energy-supply for evaporation in order to maintain a higher vapourpressure and ion density near the cathode. For the mercury cathode this assumption seems to be valid. The temperature of the cathode spot and the voltage drop in front of it, for Bi, Pb, Zn, Tl, Cd, In, Sn, Cu, is not yet exactly known. Therefore the validity of the assumption made, concerning these materials can only be proved qualitatively.