THOMSON SCATTERING DIAGNOSTICS OF ARC DISCHARGE PLASMAS CONTAINING METALLIC VAPORS

摘要

Laser Thomson scattering (LTS) has been applied to atmospheric arc discharge plasmas for the measurements of electron density (ne) and electron temperature (Te). The arc plasmas were generated between two hemispherical electrodes, which were settled in a discharge chamber. A peak voltage and a peak current of the discharge were 6 kV and 600 A, respectively. The discharge voltage and current decayed with a time constant of 25 us. The LTS measurements were performed in the temporal range of 10-50 us after the start of the discharge. The collected LTS signals were dispersed by a triple grating spectrometer and detected by an ICCD camera. As a result of the LTS measurements, spatiotemporal evolutions of ne and Te of arc discharges were obtained. Measured ne and Te values satisfied the relation calculated by the Saha equation. In addition, the decay processes of ne and Te were clearly different when the conditions of the discharges were different.