Enhanced extraction efficiency of the sputtered material from a magnetically assisted high power impulse hollow cathode

The high power impulse hollow cathode sputtering (HiPIHCS) technique was pioneered by researchers attempting to combine the high ionization degree of sputtered species in a high power impulse magnetron sputtering discharge with the highly energetic electrons from a hollow cathode (HC) in order to obtain high-density and high-energy fluxes of sputtered metal species. Hence, this novel technique may open new horizons in surface engineering, offering the ability to control, enhance and tailor coating properties by using additional electric and/or magnetic fields. However, there are still many issues to be solved, including the ionization degree of the sputtered material and the deposition rate, as well as the extraction efficiency. This work reports on the improvement of the extraction efficiency of the sputtered material in an HiPIHCS process when an external magnetic field is applied. The HiPIHCS discharge was operated with ultra-short pulses (5 s) of high voltage (600-800 V) applied directly on the HC. The obtained experimental results show that the extraction efficiency of both neutral and ionized sputtered material increases at least by a factor of two when an external magnetic field of only 15 mT is applied in the HC discharge region.