Atmospheric pressure glow discharges. Modelling and experimental data

One of the solutions to increase the efficiency of surface treatments and to avoid the drawbacks associated to low-pressure discharges (i.e. very expensive equipment and extensive outgassing of polymer surfaces) is to use glow discharges working at the atmospheric pressure (APGD). Unfortunately stable glow discharges are much more difficult to obtain at high pressure than at low pressure and it is therefore necessary to improve our understanding of this type of discharge in order to determine the parameters which play a prominent role in obtaining a stable regime. To facilitate the study the numerical modeling is a very useful tool complementing experimental information. However, in this case, there is a strong drawback as, since the discharge reaches a stable state after several periods, it is necessary to follow it over a long time (of the order of a few microseconds). As the charged particles cannot disappear at the electrodes, they accumulate for a long time and it follows that the structure of a new discharge (and consequently its stability is strongly controlled by the amount of charge released by the previous discharge). The numerical study of this type of discharge is then much more difficult to carry out than when the discharges are independent, only the propagation of an isolated discharge must be considered