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

摘要

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 × 10~3 Pa has been measured by Laser Thomson Scattering (LTS). The peak voltage between two electrodes is 1520V and the current is 3A 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: T_e decreases exponentially from 1.75 eV to 0.1 eV and n_e increases rapidly to 3.94 × 10~(20) m~(-3) from 15 ns to 115 ns then decreases to 1.17 × 10~(19) m~(-3). In the discharge with cylindrical geometric symmetry, T_e increases from ball to plate, while n_e is opposite. In the r-direction, both T_e and n_e decrease from central to edge at 3.4 mm. Value of n_e varies by 20 times from maximum to minimum and T_e is only about 1.5 times.