Effects of pressure and incident field on visible light intensity from microwave nitrogen breakdown

A model consisting of spatially averaged continuity equations for electrons and excited atoms, equations of electron momentum and energy, and an equation of photon emission is used to calculate the photon emission rate during microwave nitrogen breakdown, in order to estimate the visible light intensity. The effects of nitrogen pressure and the incident field on the photon emission rate are analyzed, when the electron density reaches the maximum value above which no ionization occurs. As nitrogen pressure increases, the photon emission rate first increases to a maximum, and then decreases. The simulated dependence of the photon emission rate on pressure is qualitatively consistent with the experimental observation. As the incident field increases, the photon emission rate increases, and the pressure corresponding to the maximum photon emission rate increases. The simulated results for breakdown electric fields and delay times agree very well with experimental data.