Laser-induced breakdown in freon-doped rare gas

Abstract

The breakdown of argon gas containing freon-12 impurity is reported. At high pressure the freon increases the breakdown threshold, while at low pressure it decreases the threshold. This behavior is shown to result from attachment and multiphoton ionization of the freon. The experiment is considered to provide further evidence for multiphoton ionization and for the cascade theory of breakdown.

Femtosecond filamentation induced fluorescence technique for atmospheric sensing*

“…The ns laser pulse ionizes the molecules/atoms of the gaseous material mainly through the following processes; [11,16] (i) multiphoton ionization of impurities, giving rise to the first few free electrons; [5] (ii) the acceleration of these free electrons through inverse bremstrahlung followed by cascade (avalanche) ionization by these electrons in the laser field of long duration (ns) resulting in a plasma or breakdown. [6][7][8][9] The series of atomic lines from the emission spectra of the plasma enable characterizing different types of molecules. However, the chemical bond between the atoms can be easily broken through electron collision.…”