Dynamic contraction of the positive column of a self-sustained glow discharge in a reacting flow

Contraction occurs when current contracts from a uniform volumetric weakly ionized plasma into a localized channel. This dynamic transition provides a promising technique for reliable ignition of ultra-lean combustion mixtures. In this work we study the dynamic contraction of the positive column of a self-sustained glow discharge in a reacting H2-O2-N2 flow. We developed a one-dimensional numerical model of the plasma contraction in a cylindrical frame. The contraction process is described by a set of time-dependent equations. We analyzed the critical conditions for transitions from the uniform to contracted state. The plasma instability in reacting flows is not only governed by the ionization-thermal mechanism, but also heat release/absorption in chemical reactions. Specifically, electron-impact fuel ionization, combustion heat release and the electron attachment to combustion-related species would shift the critical current for triggering the plasma instability. The study of the plasma instability in a combustion mixture will advance the understanding of the kinetic and thermal interaction between non-equilibrium plasma and combustion and lay foundations for the development of plasma assisted ignition.