Patent ID: 8337682

Claim:
An arc plasma source for evaporating a cathode material of a cathode by arc discharge controlled by a magnetic field, the source comprising: the cathode; a magnetic field forming mechanism arranged outside the cathode for forming a magnetic field in parallel to the center axis of the cathode near an evaporation surface at the front end of the cathode; a supporting mechanism for supporting the cathode; a cooling mechanism for cooling the cathode; and a tapered ring being truncated cone shaped and having a through-hole into which the cathode penetrates along the axial direction of the through-hole, the tapered ring being arranged to be tapered toward the evaporation surface of the cathode; wherein the tapered ring is made of a ferromagnetic material and the front end of the tapered ring is positioned coplanar with the evaporation surface of the cathode or is positioned posterior to the evaporation surface in use.