School of Science, Beijing University of Chemical Technology, Beijing 100029, China 2 .The fourth laboratory, Beijing Vacuum Electronics Research Institute, Beijing 100015,China
Funds: supported by the National Natural Science Foundation of China ( No. 50877003)
A two-dimensional model of a weakly-ionized hydrogen direct-current (DC) discharge at low pressure is simulated. In the model, the metal electron overflow and secondary electron emission coefficient at the cathode spot are introduced to represent the relationship between the electron and ion density, and the electron energy distribution function is expressed by kinetic theory. The electron current density and reaction constant reasonably set on the boundary are discussed. In addition, it is determined that 11 collision reactions play a major role in low pressure and weakly ionized hydrogen discharges. On this basis, the relationship between mobility, electrode spacing, and breakdown voltage is verified. Good agreement is achieved between the simulation curve and Paschen curve.