The invention provides a power conversion device operable in a discontinuous conduction mode under the control of a switch. In certain implementations, cyclic AWGs are employed. The cutter includes a shaft in which a substantial axial portion is fitted into a sleeve and a remaining axial portion serves as a cantilever extending out of the sleeve, and a head which is formed at a distal end of the shaft. After the entire target has been processed, the target is cooled to a predetermined lower temperature while still intermittently subjecting the target to atomic hydrogen.