The voltage–current characteristics of a boundary layer arc

Abstract

The voltage–current characteristics of a boundary layer arc were measured over wide ranges of flow velocity (Ma 0.02–1.5) and current (10–100 A) by using three different experimental combinations. The arc is held in close contact with a solid surface because of the relative motion of the surrounding gas. The measured data show reasonable agreement with the predictions of a temperature-dependent Prandtl boundary layer model. Analysis of the saturation ion current from the arc to a Langmuir probe set in the solid surface shows that the inner surface of the arc lies very close to the surface as assumed in the theoretical model. A similar arc–flow–solid configuration arises in some circuit breakers, arc heaters, gas lasers, and even spark ignition devices. The ranges of current and flow velocities in these situations generally lie within the ranges covered by the results described in this paper.