Circuit based models for understanding breakdown in a high pressure vortex waterwall argon arc lamp

Abstract

Summary form only given. Vortex water wall high pressure argon arc lamps are used to generate intense light and are capable of operating at radiative efficiencies greater than 50%. These lamps are being considered for use in a pulsed DC mode of operation in the next generation of rapid thermal processing applications. The design of an ignition power supply for this type of system poses special problems because of the electrically conducting inner water wall. The lamp head consists of a tungsten coated copper cathode, an anode located 150 mm from the cathode and a hemispherical metallic ground plane located 1 mm from the outside surface of the cylindrical glass envelope. A field enhancing pointed tip is attached to the shaft of the cathode and the anode electrode is recessed within a cylindrical metal shroud. The plasma is initiated at the pointed tip, then slides along the water wall surface before finally traversing the gap between the water wall and the anode electrode. An improved understanding of how to design the ignition power supply has been obtained by proposing three circuit based models to describe the breakdown process.