Basic data of polyatomic ion-molecule systems for flue gas discharge modelling

Abstract

In the presence of an external electric field, ion transport coefficients (ion mobility and diffusion coefficients) are closely related to the ion-neutral interaction potential. A new generalized potential model, coupled to an optimized Monte Carlo technique, has been developed for the determination of the transport coefficients of polyatomic ions in weakly ionized gases. This corresponds to the polyatomic ion-molecule systems which can affect the electrical behaviour of the flue gas discharges used for the non-thermal plasma reactor for pollution control. The ion-molecule interaction has been described by a rigid core potential model which is adapted for both polar and non-polar systems and also symmetric and asymmetric systems. Momentum transfer cross sections are then determined using a semi-classical approach. The corresponding sets of cross sections including the dominant processes in our intermediate ion energy range (elastic and mainly charge transfer in certain cases) are used in the Monte Carlo code to calculate the ion transport coefficients over a wide range of reduced electric field E/N. These ion transport data fit quite well the drift tube measurements available in the literature for the CO2+/CO2 system, and also for certain weakly polar cases. The case of the H2O+/H2O system is then considered thus giving in this highly polar system the ion swarm data for the first time in the literature. Finally, we have considered with quite good reliability some asymmetric systems such as CO2+/N2 and N2+/CO2 whose ion data are also needed for flue gas discharge modelling.

Simulation tool for atmospheric aerosol nucleation bursts

“…In this case the polarizability is to be replaced by the total effective polarizability (see Loeb, 1955). The effective polarizability is calculated as follows (see Nelson, Benhenni, Yousfi, & Eichwald, 2001):…”

Drift and reactions of positive tetratomic ions in dry, atmospheric air: Their effects on the dynamics of primary and secondary streamers

“…• The asymmetric charge transfer reaction ͑18a͒ ͑N 2 + +O 2 → O 2 + +N 2 ͒ that occurs whatever energy ͑thermal or higher͒ while its backward reaction ͑18b͒ occurs only at ion energies above 3.51 eV, corresponding to a higher E/N range. 9,17 This means that during the discharge relaxation for low E/N ͓Fig. 12͑b͔͒, the asymmetric charge transfer is the dominant process.…”

“…[8][9][10] In the present work, the elastic momentum cross section Q m , has been calculated in the framework of a semiclassical formalism based on the JWKB approximation for the phase shift, 12 using a rigid core potential model describing the ion/ molecule interaction 13…”

“…The reduced mobility shows a plateau at low E/N followed by a small hump or peak around 100 Td because the well depth energy m is higher than the thermal energy 3/2 k B T g . 9 Table II shows the zero-field mobility data of N 2 O 2 + obtained from the previous approximation compared to the Monte Carlo calculations already shown in Fig. 5.…”

“…The first aim is to determine the ion swarm data of O 4 + and N 2 O 2 + in dry air ͑80% N 2 and 20% O 2 ͒ over a large E/N range up to 1000 Td, by using a method previously developed to determine the ion swarm data for polyatomic ions, particularly in the case of N 4 + in air. [8][9][10] The second aim is to use the present ion swarm data and those previously obtained for N 4 + in dry air [8][9][10] to analyze the effect of the ionic clusters N 4 + , O 4 + , and N 2 O 2 + on the streamer dynamics generated by a positive point-to-plane corona discharge in dry air by using a two-dimensional ͑2D͒ electrodynamics physical model. 11 The influence of these positive tetratomic ions will be analyzed during the primary and secondary streamer dynamics and also during the relaxation stage of the discharge.…”