Electron power absorption in micro atmospheric pressure plasma jets driven by tailored voltage waveforms in He/N2

In atmospheric pressure capacitively coupled microplasma jets, Voltage Waveform Tailoring (VWT) was demonstrated to provide ultimate control of the Electron Energy Distribution Function (EEDF), which allows enhance and adjust generation selected neutral species by controlling electron power absorption dynamics. However, at fundamental level, physical origin these effects VWT remained unclear. Therefore, in this work, dynamics is investigated a He/N$_2$ jet with nitrogen concentration 0.05\% driven valleys waveform base frequency 13.56 MHz for different numbers harmonics using self-consistent Particle Cell simulation spatio-temporally resolved analysis based on momentum balance equation. Due local nature transport pressure, ohmic dominant. Increasing number harmonics, due peculiar shape excitation sheath collapse grounded electrode shortened relative one powered electrode. As consequence, order ensure flux compensation electrons positive ions electrode, high current through discharge time short collapse. This electric field. Close where density low field high, are accelerated energies strong ionization as well formation maximum observed. leads ambipolar that acts an reversal accelerates even higher energies. These understood detail fundamentally explain unique potential EEDF such plasmas.