Ion sheath evolution and plasma replenishment inside an 80-mm-diameter pipe for plasma-based ion implantation and deposition

The aim of this work is to know the plasma replenishment inside a pipe after the end of the application of a negative high voltage pulse in plasma-based ion implantation and deposition system. The pipe with a diameter of 80 mm and a length of 150 mm is immersed in a titanium cathodic arc generated in nitrogen gas. The plasma density inside the pipe is non-uniform mainly due to a violent vaporization of the cathode material. A transient ion sheath is produced inside the pipe by the pulse voltage application. After the end of the pulse, the plasma replenishment starts by the plasma invasion from both edges of the upstream and downstream of the pipe, because of the shortage of the plasma inside the pipe. The completion of the replenishment is dependent on the position inside the pipe because of the initial spatial distribution of the plasma species. As a result, the invasion speed also changes with the position.