CHANNEL IN A HIGH-CURRENT ARC.

The formation of the channel in a high-current arc is studied. When the primary mechanism for heat removal is radiation, the field in the channel E equals ROOT U (T)/ sigma (T), where U is the power radiated per unit volume and sigma is the conductivity. The field E has a minimum at temperatures that correspond to fully ionized plasma and it is suggested that the stable state of the channel corresponds to this minimum. This assumption replaces the other boundary condition needed for the Elenbaas equation for a freely burning arc. As a result, equations can be found for the field, the current density, and the temperature in the channel which are independent of the total arc current. These properties are compared with the available experimental data for nitrogen and argon arcs; satisfactory agreement is found.