**3.2 Plasma bias**

The plasma is generated by a DC glow discharge between a stainless steel solid cylinder, acting as an anode, and the vacuum chamber as a cathode (figure 4). The DC power supply ranged within 0-1200 V/2A. The gas admission control to the vacuum chamber drives a gas dosing valve and the work gases being nitrogen and argon. The whole device is typically operated at a 1×10-6 Torr as base pressure and, during the PIII process, the work pressure falls into the 10-2 to 10-1 Torr interval.
