Laser induced photo-detachment of O₂ in DC discharge

Abstract

Determination of the negative ion number density of O 2 and Oin a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photodetachment technique. The temporal evolution of the extra electrons resulting from the photodetachment of O 2 and Owere used to evaluate the negative ion number density. The ratio of O 2 number density to Ovaried from 0.03 to 0.22. Number density of both O 2 and Oincreased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function (EEDF) using the I-V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the a O 2 1 g D ( ) metastable state is discussed.

Observation of a significant drop of electron density in cascaded arc argon plasma doped with oxygen gas using laser Thomson scattering

“…As the electron affinity of O − and O 2 − are 1.46 eV and 0.46 eV, respectively [51], the negative ions (O − and O 2 − ) can be easily detached by the laser photon with the wavelength of 532 nm (2.33 eV), which generates the detached electrons with energy of 0.87 eV and 1.89 eV, respectively. These electrons with the specific energy will severely distort the electron energy distribution function (EEDF) [52].…”