Abstract :
A probe technique is described which can be used to measure transient changes in neutral gas density in a low-pressure gas discharge. The technique has been used to study changes in neutral gas density in the discharge space of a hydrogen thyratron on recurrent pulse load. The study reveals that the local density immediately prior to a current pulse depends on the gas filling pressure and the average value of the electrical load. During the current pulse the local density falls by an amount which depends on the pulse-current amplitude and duration, but recovers to its original value after the end of the current pulse in a few tens of microseconds. Since the arc-voltage drop, and therefore the power dissipated within the thyratron, varies with gas density and has a minimum value near the middle of the working density range, the observed changes in density result in the complex relation which exists between the energy losses in the thyratron and the electrical load to which it is subjected.
