This is the arc evaporation cathode for a PVD coating system.
This design can let argon gas flows symmetrically through the cathode body and
uniformly across the target surface, eliminating localized high pressure regions on the target surface.
Premature target burn-through and skewed distribution are prevented. Argon gas flowing from the target surface creates a localized high pressure which reduces the tendency of sputtered material to redeposit on the target surface.