Theoretical Study of the Influence of H2O on Parameters of Low-Temperature Plasma in Humid Mixtures
Janda M., Hensel K., Martišovitš V., Morvová M.
22nd Symposium on Plasma Physics and Technology SPPT, Prague (Czech Republic), June 26-29, 39-40 (2006)
request a copy
|
|
Abstract: We performed series of Monte Carlo (MC) electron dynamic simulations in dry and humid
N2 and CO2, in order to get electron energy distribution functions (EEDFs) and electron mean
energy (ε), rate coefficients of electron impact reactions, mean free path (λ), drift velocity
(vd) and collisional frequency of electrons (ν), as functions of reduced electric fields strength
(E/N) and concentration of H2O.
The aim was to test the latest compilation of cross-sections
for H2O, the applicability of applied MC method, and the effect of the concentration of H2O.
The most important processes shaping EEDFs are vibrational excitations of N2 and CO2, and
rotational excitation of H2O, in ranges 1 – 4 eV, 2 – 5 eV, and below 0.3 eV, respectively. The
energy losses for each process may differ significantly. Thus, various parameters have
different sensitivity to the concentration of H2O, e. g. ν and λ are more sensitive than ε and
vd. The sensitivity depends strongly also on the E/N. For E/N > 100 Td the parameters may be
obtained as their linear combinations in pure gases. The deviation is below 5%. For E/N less
than 100 Td, the deviation increases rapidly and MC simulations in mixtures are necessary.
In weak field, the presence of H2O increases the rate coefficients of most studied reactions.
Processes with higher threshold energy imply stronger acceleration.
These calculations represent the first stage in a more complex modelling of atmospheric
pressure non-equilibrium electrical discharges and plasma induced chemical processes used
for the decomposition of various pollutants.
|
