Ionization efficiency in a geometrical pinched cascaded arc

Remote deposition allows separate optimization of the plasma production source and of the deposition process. To improve the ionization performance of the source, an argon cascaded are plasma is studied by simulations. improvements of the source performance in ion yield are achieved by constricting the bore of the are channel near the entrance. Such a geometrical pinch construction leads to a higher neutral density at the are inlet which results in increased ionization in the cascaded are. The improved ionization performance is analysed by solving numerically the conservation laws of mass, momentum and energy in a two-dimensional hydrodynamic approximation using a pressure linked algorithm. The results are compared with those of a simplified one-dimensional formulation in order to identify the main mechanisms. The results indicate that, by constricting the bore of the are channel, a very high ionization degree can be obtained.