High-current arcs in transverse magnetic fields in air at atmospheric pressure

This paper gives measurements of the velocity and voltage, and estimates of the size (`effective drag width¿) of electric arcs driven by transverse magnetic fields in air at atmospheric pressure. Ranges of parameters covered are: electrode spacing up to 10cm, magnetic field up to 1.75Wb/m2, and current up to 20000A. Several different electrode configurations and dimensions, and various electrode materials, are used, and conditions have been found where arc movement is virtually independent of the electrode material and spacing. Some comments on the interaction of electrode and column influences are made. In particular, it is noted that electrode influences can be significant under some conditions, and should then be accounted for, in the analysis of experimental results by similarity parameters based on column theory. Although the condensation of data achieved by similarity parameters is very great and highly illuminating in that under many conditions it is possible to predict arc velocity and column voltage gradient within about ±50%, given only the arc current, magnetic field, and electrode spacing and material, there is still much variation within these limits which is difficult to predict. Thus the dependence of the behaviour of an arc on the precise nature of its environment should not be overlooked.