Normalized spatio-temporal plots of the measured emission of the 706.5 nm He I line (a) and normalized (to the maximum value of (b)) spatio-temporal plots of the electron-impact excitation rate obtained from the simulations for different choices of the surfaces coefficients listed in table 2. Discharge conditions: 355 V driving voltage amplitude, 1 slm He flow, 0.5 sccm N2 flow. The powered electrode is situated at x = 0, while the grounded electrode is located at x = 1 mm. The sheath edge position (white dashed lines) is calculated using the Brinkmann criterion [82] and is shown as white dashed line in the simulation plots.
Experimental data are marked as exp
Simulation data are marked as sim
x [t/TRf] , y[mm]
(Figure7a): exp Exc rate [a. u.] emission of 706.5nm line for 270V, 315V and 355V respectively
(Figure7b-7e): sim Exc. Rate [a. u.] normalized to the maximum value of (b) electron-impact excitation rate from the He I ground state into the He I (3s)3 S1-state for SEE ON α = 0.5, SEE OFF α = 0, SEE ON α = 0 and SEE OFF α = 0.5 respectively