Spatially resolved absolute densities of helium 23S1 metastables obtained experimentally for fixed N = 4 and 0.05% of N_2 admixture concentrations for ‘peaks’ and ‘valleys’ waveforms (a). Space- and time-averaged densities of the helium metastables for different numbers of harmonics and N_2 admixture concentrations for ‘peaks’- waveforms (b). The powered electrode is located at x = 0, while the grounded electrode is at x = 1 mm. The base frequency is = 13.56 MHz, φpp = 500 V
Experimental data are marked as exp
Simulation data are marked as sim
x[mm]
(Figure6a): Exp absolute helium metastable density [cm^{-3}]
(Figure6b): Exp and sim space and time averaged densities of helium metastables [cm^{-3}]