THEORETICAL-ANALYSIS OF GAS-BREAKDOWN CHARACTERISTIC THROUGH A NARROWDISCHARGE-TUBE

The breakdown characteristic through a narrow discharge tube, such as a plasma tube of gas lasers, is different from that between parallel e lectrodes given by Paschen's law. The physical modelling of the gas br eakdown process in a narrow tube is established based on Townsend disc harge theory. This kind of breakdown process can be divided into two s tages. The first one is the changing process of the guiding electrical field of wall charges formed by the deposition of charged particles f rom the avalanche, and the second one is the electron avalanche proces s through the whole discharge tube. From the physical modelling mentio ned above, the parameters just before breakdown and the breakdown char acteristic through a narrow discharge tube will be analysed theoretica lly. It can be seen that the breakdown potential is dependent not only on the pressure, the tube length, and the species of gas but also on the diameter of the discharge tube. Finally, the calculated results ar e compared with the experimental results and the errors are discussed.