Axial magnetic field effects on ignition switches

This report describes research on the effects of axial magnetic fields on ignitron switches. Investigations of effects of the field on the arc resistance, holdoff voltage, and visible plasma parameters were carried out on three different types of ignitrons; a commercial NL-2909 ignitron, two glass-walled ignitrons, and a specially built demountable ignitron. All measurements were made in a critically damped configuration utilizing either a 2.56 mF, 10 kV capacitor bank or a 1.89 |xF, 60 kV capacitor. Diagnostics included voltage and current monitoring along with high speed photography performed by a Dynafax framing camera. Model 326, and a TRW image converter camera. The photographic techniques were performed on the glass-walled tubes alone. Effects of the insertion of a dielectric shield into the demountable ignitron were studied. Additional measurements of risetime dependence of the arc voltage were performed on the demountable ignitron.