The performance of new, redesigned ignitron tubes in axial magnetic fields

The test results from two special ignitron tubes exposed to axial magnetic fields are described. The experiments were made using a capacitor bank with 2.56 mF total capacitance and 128 kJ maximum energy at 10 kV. To study the effects of axial magnetic fields on the switching characteristics, including the self-breakdown voltage of the tubes, the test specimens were mounted inside four high-power, water-cooled electromagnets. The highest magnetic field which can be generated by this arrangement is 0.7 T for conduction tests and 1.0 T for high-voltage tests. The test results include voltage and current measurements along with optical diagnostics performed on a special tube which provides optical access to the discharge volume. The ignitron tubes tested were a small, glass-walled tube and one experimental size-D tube with stainless steel walls. Particular attention is given to the failure of the glass tube and the change in holdoff ability with and without magnetic field for both the metal and glass ignitrons