Two-dimensional Thomson scattering diagnostics of pulsed discharges produced at atmospheric pressure

Laser Thomson scattering (LTS) method has been applied to measure two dimensional distributions of electron density (n_e) and electron temperature (T_e) of a pulsed discharge in Ne gas at a pressure of 400 Torr. Such a discharge was produced with good reproducibility by using a set of electrodes composed of a needle and a hemisphere with a spacing gap of 0.5 mm. The values of n_e and T_e at t = 25 ns after the start of the discharge and at the center of the discharge were evaluated to be 4.6 × 10²² m^-3 and 1.0 eV, respectively. Based on the observed signal intensity and noise components, signal-to-noise ratios were examined and the way to apply present diagnostic system to the discharge plasma with an electron density as low as 10¹⁸ m^-3 was discussed.