Space- and time-averaged values of the helium metastable density as a function of the nitrogen admixture concentrations obtained experimentally and from the PIC simulations. The base frequency is f_0 = 13.56 MHz, N = 4, and φpp = 500 V.
Experimental data are marked as exp
Simulation data are marked as sim
Nitrogen concentrateion[%]
Figure13a: Sim and exp data for time averaged helium metastable dens [cm^{-3}]
Figure13a_fit: sim fit [cm^{-3}]