Capacitively coupled radio-frequency discharges in nitrogen at low-pressure

This paper studies capacitively coupled radio-frequency discharges (13.56 MHz frequency) in pure nitrogen, produced within the LATMOS and the GREMI cylindrical parallel-plate reactors, surrounded by a lateral grounded grid, at 2-30 W coupled powers and 0.2-1 mbar pressures. Simulations use an hybrid code [1] that couples a 2D ($r$,$z)$ time-dependent fluid module for the charged particles and a 0D kinetic module for the nitrogen (atomic and molecular) neutral species. The coupling between these modules adopts the local mean energy approximation to define space-time dependent electron parameters for the fluid module and to work-out space-time average rates for the kinetic module. The model gives good predictions for the self-bias voltage and for the intensities of radiative transitions (average and spatially-resolved OES measurements) with the nitrogen SPS and FNS, and with the argon 811nm atomic line (present as an actinometer). Model results underestimate the experimental electron density (average resonant-cavity measurements) by a factor of 3-4. \\[4pt] [1] L. Marques et al, J. Appl. Phys. 102, 063305 (2007).