Plasma activation mechanisms governed by specific energy input: Potential and perspectives

Abstract

In a low-temperature plasma, the electrons pick up energy from the electric field in collisions with atoms and molecules, gaining high kinetic energy that must be sufficient for ionizing reactions to sustain the plasma. For molecular gases, an average energy per heavy gas particle is thus available in the plasma, the specific energy input, yielding plasma activation by inelastic collisions. Following a distribution law, the probability for the activation mechanism can be described by an Arrhenius-like equation. The potential of this approach is demonstrated on the basis of plasma polymerization and plasma CO2 conversion. For perspective, energy efficiencies are discussed as a function of conversion indicating the optimum that can be achieved by electron impact activation compared with additional ways of energy transfer, probably depending on certain constraints.