Application of two-photon absorption laser induced fluorescence to validate actinometry measurements of absolute atomic oxygen number density based on improved EEDFs obtained from PIC simulations.

Actinometry is a non-invasive optical technique that allows absolute atomic oxygen density determination within a plasma provided certain conditions are met. However, the technique is sensitive to to the accuracy of the Electron Energy Distribution Function (EEDF). A Maxwellian distribution is often used for actinometry calculations, but this is typically just an approximation. A Particle in Cell (PIC) code is used to try and generate a more accurate EEDF to improve the actinometry results. To do this the electron density in the plasma is measured using a hairpin probe and compared to the electron density predicted by the PIC code. The code is adjusted to get a reasonable agreement with the hairpin probe electron densities. The corresponding EEDF from the PIC code is then used in the actinoometry model to calculate the atomic oxygen density in the plasma. The actinometry results are compared to oxygen density measurements made using Two-photon Absorption Laser Induced Fluorescence to validate the actinometry results.