Thyratron grid protection and monitor system

Thyratrons are still widely used in high power pulse systems. A technique to measure cathode state and thereby predict remaining tube life would be a very valuable system tool. Thyratron triggering circuits also have to survive a very large grid to cathode spike when the thyratron switches on. This spike becomes larger and longer as the tube ages and often eventually damages the trigger unit. However, the characteristics of this spike can give a useful prediction of overall behaviour and ageing characteristics of the tube. The paper will describe a technique using a saturable reactor that provides both trigger circuit protection and a method of monitoring of the spike behaviour that can be used to gain an indication of overall remaining tube life.