Abstract: An electric arc ion plating apparatus to coat a metal material on an object includes: (a) an vacuum chamber; (b) an electric arc bombardment chamber in the vacuum chamber, comprising an anode, a cathode target, and an arc triggering electrode to generate metal particles when a voltage is applied on the anode and the cathode, and on the arc triggering electrode; and (c) a magnetic coil having a longitudinal axis. The magnetic coil emanates from the electric arc bombardment chamber and encloses at least a part of the electric bombardment chamber. The magnetic coil contains a constant-diameter section enclosing and immediately emanating from the electric arc bombardment chamber to guide the metal particles away from the cathode and toward the object, and a varying-diameter section away from the electric arc bombardment chamber to provide optimum distribution of the metal particles before they reach the object surface.