Mechanism of Low Pressure dc Breakdown in a Thermo-Cathode Gas Discharge

A theory about the dc breakdown process of a gas discharge with thermocathode in a very low pressure (10^-2 Pa) is provided. The mobility of ions due to ion-neutral charge exchange collisions is mainly responsible for the space cumulative effect of positive charges and the formation of the virtual anode. A numerical result for the breakdown process of the argon gas discharge is given.