Experimental confirmation of transitions in the discharge operation mode in low-pressure capacitively coupled Ne plasmas*

In this work, the electron power absorption and ionization dynamics in low-pressure discharges operated in Ne are studied and a detailed comparison of simulated and experimental results is provided in a wide parameter regime. 1d3v PIC/MCC simulations and PROES measurements are performed at different driving frequencies, pressures and voltage amplitudes in a geometrically symmetric CCP reactor. Both in simulations and experiments, a transition of the discharge operation mode from $\alpha $ to $\gamma $ is found by increasing the voltage amplitude at a fixed frequency and pressure, as well as by increasing the pressure at a fixed frequency and voltage amplitude. However, the simulations and the experiments suggest different voltage amplitudes/pressures at which the transition happens. This study reveals the applicability of PROES (which provides the spatio-temporal distribution of the excitation dynamics of the Ne 2p1 state) to probe the discharge operation mode (which is determined by the spatio-temporal distribution of the ionization dynamics) under various discharge conditions.