Numerical simulation versus experiment on a long hollow target PVD reactor

Summary form only given. The work described has been performed in the general framework of a pre-industrial PVD reactor development. This device is devoted to the online coating of ceramic fibers for aerospace industries and, to achieve this task, the fiber passes axially through an hollow cylindrical target which is sputtered by the confined plasma. This unusual geometry has been chosen to maximize the flux of sputtered atoms on the fiber although the ratio between facing surfaces remains very low (/spl sim/10/sup -3/), and to produce a columnar plasma which should ideally stand close to the inner surface of the target. It should also be noted that the ratio between the length and the radius of the confining target is high (/spl sim/30), and can be suspected to generate instabilities. We recently started Monte Carlo simulations to reproduce, understand and fix this phenomenon. First computations show that electrons are accelerated from the gun, following the magnetic field lines (as it is classically expected) but loose their energy in the first collisions which occur at the top of the target. Then, they are probably not able to recover this lost energy in the constant plasma potential. Further numerical results should confirm this hypothesis. In this case, post-accelerating strategies will be implemented to enhance the sputtering and the coating processes.