Arc source designs

Abstract

This chapter discusses the practical application of physics to arc source design. The chapter discusses the design of continuous sources. Currently, there are many examples of arc deposition of coatings on a commercial scale. There are numerous variations of cathodic-arc source designs, but most can be classified by pulse duration and macroparticle filtering, and all are governed by the same basic rules. Pulse duration is typically divided into two categories, which can be delineated by the arc power source. If the arc is sustained only for the duration of the discharge of a capacitor, it is designated pulsed. If the arc is sustained by a DC current source, it is designated continuous or at least quasi-continuous. Pulsed and continuous sources each have their own advantages. In a pulsed source, the arc duration is typically short enough that direct cathode cooling is not needed, which simplifies the design, and makes changing cathodes a simple matter. Also, confinement of the arc spot to the cathode surface is less of problem, as the duration is typically short enough that there is insufficient time for the arc spot to move off the cathode surface. Continuous sources have correspondingly higher rates, but the cathode must be designed to dissipate the heat generated by the arc as well. Since the heating is concentrated in small spot, direct water cooling is typically required. This leads to difficulty in changing cathodes and limits the use of some low thermal conductivity materials.