An evaporation source capable of depositing extremely adherent coatings at high rates on conducting substrates is described. A high-current arc generated by a hot hollow cathode of the type developed by Lidsky et al. is directed upon a hearth containing the coating material. The arc evaporates and ionizes the material. Application of a potential to the substrate causes the acceleration of the ions toward the substrate. Ions bombarding the substrate surface remove adsorbed species and penetrate the lattice, producing excellent adhesion. Strengths exceeding 3.5×109 dyn cm−2 (51 000 psi) have been measured. Design details, performance data, and properties of the coatings are covered.