Recent advances in high power ignitron development

The development of high-power ignitrons with peak current ratings of up to 1000 kA and simultaneous charge transfer rates of 250-500 C is described. The authors discuss the advances made in high-power ignitron switching capabilities in a comparison study between conventional Size D and Size E tubes, demountable experimental tubes and the new NL-9000. The differences in tube design are shown together with the associated peak current and charge transfer capabilities and lifetime expectancies. The critical design criteria are the anode shape and placement in order to control the plasma and prevent prefires. Tube failure modes and recent studies on alternate ignitor schemes are presented. In addition, results of plasma diagnostics performed on a demountable ignitron with optical access to the discharge plasma are shown. Time-resolved images of the interference patterns from an optical Mach-Zehnder interferometer were recorded with a mechanical high-speed camera and evaluated with the help of image processing