[20a-B11-1~10] 8.1 Plasma production and diagnostics

[20a-B11-3] Measurements of electron velocity distribution function of streamer discharges produced in the air using Thomson scattering

〇Kentarou Tomita¹, Kiichiro Uchino¹, Yuki Inada², Atsushi Komuro³, Xiang Zhang⁴, Ryo Ono⁴ (1.Ksyuhu Univ., 2.Saitama Univ., 3.Tohoku Univ., 4.Univ. Tokyo)

Keywords:streamer discharge, Thomson scattering, electron velocity distribution function

This paper reports a first experimental result that directly shows an electron velocity distribution function (EVDF) in a streamer discharge produced in the atmospheric air using laser Thomson scattering (LTS). For the discharge production, a pulsed 30 kV voltage was applied between a set of electrodes with a gap of 13 mm. Such the discharge was produced with an excellent reproducibility in time and space by using a specially-designed electrode set composed of five needles and a plate. The LTS was performed at the secondary streamer phase with a repetition rate of 2 Hz. A value of electron density was 2×10²⁰ m^-3. However, because of a huge amount of rotational Raman scattering from N₂ and O₂, the LTS signal from 20,000 laser-shot was needed to obtain a clear EVDF. It was found that the measured EVDF has deviated from the Maxwellian distribution.