Mb. Schulman et H. Schellekens, Visualization and characterization of high-current diffuse vacuum arcs on axial magnetic field contacts, IEEE PLAS S, 28(2), 2000, pp. 443-452
We have investigated the behavior of drawn vacuum arcs for several designs
of axial magnetic field (AMF) contacts using high-speed digital photography
and are voltage measurements. As the peak current was increased, a gradual
transition occurred in the are appearance from a multiple cathode-spot are
to the high-current diffuse mode, and then to a high-current diffuse colum
nar mode. Two relatively simple models based on the literature are used to
explain the results. The first is an empirical criterion for using the are
voltage behavior to determine the maximum are current for which an AMF geom
etry can produce a high-current diffuse mode from the initial bridge column
are. The second model predicts the highest are current that can be forced
into a fully diffuse mode for given values of the AMF and the contact arcin
g radius. The predictions of these models are compared to our experimental
and analytical results.