Imaging the separation of cathodic arc plasma and macroparticles in curved magnetic filters

Cathodic vacuum arc plasmas can be used to produce well-adherent, dense, high-quality films and coatings, provided macroparticles are removed from the plasma. Both plasma and macroparticles are produced at cathode spots, and in most cases both can easily be observed because they emit light. The nature of this light emission is briefly discussed. Using open, curved solenoids as magnetic filters, one can readily optically record the separation of plasma and macroparticles by the filter. Imaging can be used as a powerful tool to help developing macroparticle filters and optimizing their design.