Thyratron Grid Protection and Monitor System

Summary form only given. Thyratrons are still widely used in high power pulse applications. A system able to measure cathode state and thereby predict remaining tube life would be a very valuable system tool. This paper discusses how such a system could be implemented. Thyratron triggering circuits have to survive a very large grid to cathode voltage spike each time the thyratron switches on. This spike becomes larger and longer as the tube ages, but also, more importantly, if the thyratron pre-fires (switches on without trigger pulses). Grid spikes are often the reason for damage to the trigger generator circuit. The characteristics of the grid spike, however, ought to give a useful prediction of the overall behavior and ageing characteristics of the tube. If implemented such a system could permit planned maintenance and minimize down time of a system. The paper will describe a technique that provides both trigger circuit protection and a monitor of spike behavior that can be used to gam an indication of overall remaining tube life. The paper will also give an overview of the characteristics of thyratron triggering and how they influence the spike. The protection and monitoring systems that will permit useful tube characteristics to be displayed will be described along with practical results and implementations.