Mechanism of enhanced plasma transport of vacuum arc plasma through curvedmagnetic ducts

The mechanism of the enhanced transport efficiency in a vacuum are plasma s ource equipped with a curved magnetic filter is investigated. The relations hip between the transported ion current and the cathodic are current is det ermined, and our results suggest that the outer and inner walls of the duct interact with the plasma independently. The plasma flux is composed of two components: a diffusion flux in the transverse direction due to particle c ollisions, and a drift flux due to the ion inertia. The inner wall of the m agnetic duct sees only the diffusion flux while the outer wall receives bot h fluxes. Thus, applying a positive potential to the outer duct wall reflec ts the ions and increases the output current. Our experimental data also sh ow that biasing both sides of the duct is more effective than biasing the o uter wall alone. (C) 1999 American Vacuum Society. [S0734-2101(99)03005-5].