Caption: The powered electrode is located at x = 0, while the grounded electrode is at x = 1 mm. The base frequency is 13.56 MHz and the peak-to-peak value of the driving voltage waveform is kept constant at 500 V. The concentration of the N2 admixture is 0.05%. The columns show data for different numbers of consecutive driving harmonics, N.

Experimental data are marked as exp
Simulation data are marked as sim
(Figure4a-4d): x (mm), exp Helium metastable densities (cm-3)
(Figure4e-4h): x (mm), sim He metastable densities (cm-3)
(Figure4i-4l): x (mm), sim averaged Helium metastable densities (cm-3)
(Figure4m-4p): x (mm), sim Source (cm-3 s-1) Singlets and Triplets
(Figure4r-4u): x (mm), sim exc. Rate (cm-3 s-1)
Harmonics:
N = 1: a, e, i, m, r
N = 2: b, f, j, n, s
N = 3: c, g, k, o, t
N = 4: d, h, l, p, u