The spatial-temporal distribution of the electron density and temperature in nanosecond pulsed discharge plasma measured by laser Thomson scattering

Abstract

The spatial-temporal distribution of the electron temperature (Te) and density (ne) in a nanosecond pulsed discharge (NPD) argon plasma with a ball-to-plate electrode configuration at 2 × 103 Pa has been measured by Laser Thomson Scattering (LTS). The peak voltage between two electrodes is 1520 V and the current is 3 A when the ball-like electrode is connected to the negative high voltage. The results indicate that it is possible to enhance the electron density of the plasma discharge using the rising edge of pulse voltage. The measured plasma parameters: Te decreases exponentially from 1.75 eV to 0.1 eV and ne increases rapidly to 3.94 × 1020 m−3 from 15 ns to 115 ns then decreases to 1.17 × 1019 m−3. In the discharge with cylindrical geometric symmetry, Te increases from ball to plate, while ne is opposite. In the r-direction, both Te and ne decrease from central to edge at 3.4 mm. Value of ne varies by 20 times from maximum to minimum and Te is only about 1.5 times.