Laser Thomson Scattering Measurement to Diagnose the Low Temperature Plasmas

This paper describes how to measure the plasma temperature and density using laser Thomson scattering signal. Electron energy probability functions (EEPFs) having a fine resolution of electron energy were measured in low-pressure inductively coupled plasma with laser Thomson scattering method (LTS) at various plasma conditions (rf powers and gas pressures) and compared with the EEPFs measured by a single Langmuir probe (SLP) at the same experimental conditions. The result of LTS showed that the measured electron density normally increases with the rf power and the gas pressure, and the electron temperature decreased with the rf power and the gas pressure. The results have a good agreement not only with the previous reports qualitatively but also with our SLP measurement result quantitatively.