VACUUM ARC PLASMA TRANSPORT THROUGH A MAGNETIC DUCT WITH A BIASED ELECTRODE AT THE OUTER WALL

Metal plasma formed by a vacuum arc plasma source can be passed through a toroidal-section magnetic duct for the filtering of macroparticles from the plasma stream. In order to maximize the plasma transport efficiency of the filter the duct wall should be biased, typically to a positive voltage of about 10–20 V. In some cases it is not convenient to bias the duct, for example if the duct wall is part of the grounded vacuum system. However, a positively biased electrode inserted into the duct along its outer major circumference can serve a similar purpose. In this article, we describe our results confirming and quantifying this effect. We also show the parametric dependence of the duct transport on the experimental variables.