THEORETICAL-ANALYSIS OF GAS-BREAKDOWN CHARACTERISTIC THROUGH A NARROW DISCHARGE-TUBE

The breakdown characteristic through a narrow discharge tube, such as a plasma tube of gas lasers, is different from that between parallel electrodes given by Paschen's law. The physical modelling of the gas breakdown process in a narrow tube is established based on Townsend discharge theory. This kind of breakdown process can be divided into two stages. The first one is the changing process of the guiding electrical field of wall charges formed by the deposition of charged particles from the avalanche, and the second one is the electron avalanche process through the whole discharge tube. From the physical modelling mentioned above, the parameters just before breakdown and the breakdown characteristic through a narrow discharge tube will be analysed theoretically. 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 are compared with the experimental results and the errors are discussed.