Spatial distributions of absolute densities of argon metastable state 3p54s in a Gaseous Electronics Conference Reference Cell

The spatial distributions of the 3p54s metastable state of Ar have been measured in radio frequency argon plasmas in a Gaseous Electronics Conference Reference Cell by means of high resolution absorption spectroscopy. A single-mode, tunable diode laser has been used to obtain absorption profiles at 750 and 801 nm. Spatial profiles across the gap between electrodes have been measured with 1 mm resolution for various pressures (0.15–1.0 Torr) and plasma powers (1–320 W). The densities of 3p54s metastable were obtained from integrated absorption profiles.