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 (ne) and electron temperature (Te) 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 ne and Te 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.