Experimental investigation of emission intensities in an inductively coupled afterglow neon plasma

Experimental results of time-resolved optical emission intensities of atomic neon lines (585.2 and 640.2 nm) in a pulsed, low pressure (10-95mTorr) inductively coupled afterglow neon plasma are presented. It is found that the light intensity at 585.2 nm decays exponentially but at 640.2 nm shows a typical bi-exponential decay after the rf power is turned off. Since the population of these two excited levels is generated by inelastic collisions between electrons and atomic neon (1s(5) metastable and ground state), the evolution of these two emission lines can also be estimated by a simple collisional-radiative (CR) model which uses time-dependent results of EEPF and the concentration of 1s5 atoms, both of which can be measured by using optical absorption techniques and a Langmuir probe. It is found that the measured evolution of the emission intensity at 640.2 nm has an excellent agreement with that from the model, over a long time interval after the rf power is turned off (from 20 to 150 mu s), as long as the measured EEPF is used instead of an assumed Maxwellian.