Average electron temperature estimation of streamer discharge in ambient air.

The electron temperature of small streamer plasmas with low ionization degree is difficult to measure using existing diagnostic technologies such as Langmuir probe and laser Thomson scattering. In this report, we introduce a method of average electron temperature estimation based on the electron continuity equation. The equation includes a temporal derivative of electron density as the summation of diffusion current, drift current, and electron gain/loss events. In the considered example, the electron density is measured using the Rayleigh scattering while the currents and the rate coefficients of those events are functions of the electric field, electron collision frequency, and electron temperature. Therefore, once the electric field and collision frequency are either measured or estimated, the only unknown in the equation is the average electron temperature which can be solved. It was estimated that electron temperature in the streamer peaks at about 3.9 eV for the given example.