MACROPARTICLE DISTRIBUTION IN A QUARTER-TORUS PLASMA DUCT OF A FILTERED VACUUM-ARC DEPOSITION SYSTEM

The macroparticle (MP) flux distribution in a quarter-torus filtered v acuum are deposition system was experimentally investigated and compar ed with theoretical predictions based on a previously developed model. The average MP flux was measured by collecting the MPs generated from a Ti cathode on substrates located at different radial positions on t he entrance and the exit planes of the quarter-torus filter, and measu ring the MP size distribution function using an automated microscopic image analysis system. The average MP flux along the torus centre line decreased by a factor of 50 from the entrance to the exit, while the average MP flux decrease near the outer wall of the torus was more mod erate. The flux near the outer wall was greater by a factor of three t han the centreline flux. Increasing the toroidal magnetic field from 4 to 10 mT resulted in no substantial change in the MP flux on the cent reline, while near the outer wall it decreased by a factor of two. The experimental results on the MP flux in the near outer wall region are consistent with electrostatic reflection of the charged MPs by the ch arged wall.