Characteristics of a direct current （DC） discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its stead...Characteristics of a direct current （DC） discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its steady state till it takes a period of time. Moreover, the required time increases and the current density of the steady state decreases with increasing the gap width. Through analyzing the spatial distributions of the electron density, the ion density and the electric field at different discharge moments, it is found that the DC discharge starts with a Townsend regime, then transits to a glow regime. In addition, the discharge operates in a normal glow mode or an abnormal glow one under different parameters, such as the gap width, the ballast resistors, and the secondary electron emission coefficients, judged by its voltage-current characteristics.展开更多
A one-dimensional fluid model has been used to describe the effect of radio frequency （RF） on the characteristics of carbon dioxide （CO2）, nitrogen （N2） and helium （He） mixture discharge at 120 mbar in fast-ax...A one-dimensional fluid model has been used to describe the effect of radio frequency （RF） on the characteristics of carbon dioxide （CO2）, nitrogen （N2） and helium （He） mixture discharge at 120 mbar in fast-axial- flow RF-excited CO2 laser. A finite difference method was applied to solve the one-dimensional fluid model. The simulation results show that the spatial distributions of electron density and current density rely strongly on the modulating driven frequency. When the excitation fre- quency changes from 5 to 45 MHz, the plasma discharge is always in a mode. Moreover, as the excitation frequency increasing, the higher densities of COv and N2vib can be obtained, which is important to get higher excitation efficiency for the upper laser level.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11575050 and 10805013)the Midwest Universities Comprehensive Strength Promotion Project+1 种基金the Natural Science Foundation of Hebei Province,China(Grant Nos.A2016201042 and A2015201092)the Research Foundation of Education Bureau of Hebei Province,China(Grant No.LJRC011)
文摘Characteristics of a direct current （DC） discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its steady state till it takes a period of time. Moreover, the required time increases and the current density of the steady state decreases with increasing the gap width. Through analyzing the spatial distributions of the electron density, the ion density and the electric field at different discharge moments, it is found that the DC discharge starts with a Townsend regime, then transits to a glow regime. In addition, the discharge operates in a normal glow mode or an abnormal glow one under different parameters, such as the gap width, the ballast resistors, and the secondary electron emission coefficients, judged by its voltage-current characteristics.
文摘A one-dimensional fluid model has been used to describe the effect of radio frequency （RF） on the characteristics of carbon dioxide （CO2）, nitrogen （N2） and helium （He） mixture discharge at 120 mbar in fast-axial- flow RF-excited CO2 laser. A finite difference method was applied to solve the one-dimensional fluid model. The simulation results show that the spatial distributions of electron density and current density rely strongly on the modulating driven frequency. When the excitation fre- quency changes from 5 to 45 MHz, the plasma discharge is always in a mode. Moreover, as the excitation frequency increasing, the higher densities of COv and N2vib can be obtained, which is important to get higher excitation efficiency for the upper laser level.
