Sensitivity analysis via kinetic global modeling of rotating spokes in HiPIMS
Sara Gallian, Jan Trieschmann, Thomas Mussenbrock, William N. G. Hitchon, Ralf Peter Brinkmann
66th Annual Gaseous Electronics Conference (GEC), Princeton (New Jersey), USA, 30 September - 04 October (oral contribution)
High Power Impulse Magnetron Sputtering discharges are characterized by high density plasma (peak electron density 10^18 - 10^20 m^-3 ) in a strong magnetic field (100 mT), with highly energetic secondary electrons (500 - 1000 eV). The combination of these factors results in a discharge showing a vast range of instabilities, in particular, a single rotating high emissivity region is often observed. This highly ionized region -or spoke- shows a stationary behavior in the current plateau region and rotates with [some] kHz. We apply a global model that evolves the electron energy distribution function self-consistently with the rate equations for Ar and Al species. The volume average is performed only in the structure region and a net neutral flux term is imposed to model the spoke rotation. Outside the spoke region, the neutral densities are evolved according to a phenomenological fluid model. The model is solved using a re- laxation method. We present a sensitivity analysis of the resulting steady state on the different physical mechanisms and comment on the anomalous electron transport observed.
The authors gratefully acknowledge funding by the Deutsche Forschungsgemeinschaft within the frame of SFB-TR 87.
A.Hecimovic et al.(2013), submitted. S. Gallian et al. (2013), submitted.