The Effective Periphery of a High Pressure Arc

A brief account is given of ideas which are aimed at providing a common reference point for theoretical treatments of arc problems through the equations of continuum magne-to-fluid-dynamics. By unifying theoretical solutions in the manner described, their usefulness in analyzing the results of experimental investigations may be greatly enhanced. The ideas center on the concept of an isothermal arc periphery, the temperature of which is regarded as an artificial gas property to be derived from the measured voltage gradient-current characteristic of a wall-stabilized arc of low power gradient. Evidence in support of this concept is given for various types of arc in nitrogen at one atmosphere pressure. Some of the implications of the use of an effective periphery of a high pressure arc are examined, and a suggestion is made for the complete set of boundary conditions to be applied at the periphery.