Fluid simulation on effect of power-off duration on plasma characteristics in pulse-modulated RF atmospheric argon DBD: reverse electric field and double ionization peaks

For pulse-modulated atmospheric argon RF dielectric barrier discharges, a one-dimensional plasma fluid model is established by using the drift-diffusion approximation, and the model is solved by a finite difference method and numerical results are obtained. The results show that a band-shaped reverse electric field, with the direction to the bulk plasma region, forms near the powered dielectric surface due to the beginning of the power-on phase. The rapid establishment of the driving electric field determines the strength of the reverse electric field and motivates the migration and recombination of electrons to powered dielectric surface, which will strengthen the space charge field whose direction points toward the powered dielectric surface. As the space charge field gradually dominates and the reverse electric field dissipates, the sheath is established as a consequence. In addition, when the applied voltage amplitude is 800 V, the reverse electric field appears after a power-off duration of more than 2 RF cycles. As the power-off duration increases, the strength of the reverse electric field increases significantly, and the phenomenon of the double ionization peaks appears. When the power-off duration is longer than 600 RF cycles, the intensity of the ionization peak generated by the reverse electric field begins to exceed that of the normal ionization peak.