Speaker
Carlos Daniel Pintassilgo
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/I5.312.pdf
Kinetic mechanisms in air plasmas
C. D. Pintassilgo1,2, V. Guerra1
1
Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico,
Universidade de Lisboa, Lisboa, Portugal
2
Dep. de Engenharia Física, Faculdade de Engenharia,
Universidade do Porto, Porto, Portugal
This work presents a comprehensive modelling study on the most important kinetic
mechanisms that take place in air plasmas at low pressures (p ~1 Torr). Within this purpose
we adopt three different experimental situations in synthetic dry air (N2-20%O2): (i) single
DC pulsed plasmas; (ii) their afterglows and (iii) repetitively DC pulsed discharges, each of
them produced in a cylindrical tube with inner radius of 1 cm, considering pulse durations of
the order of a few milliseconds, as reported in [1, 2].
Our simulations for the pulsed discharge are based on the numerical solutions of the
electron Boltzmann equation coupled to the system of time-dependent rate-balance equations
which incorporates the kinetics of the most populated heavy (neutral and ionic) species
produced in an air mixture including the vibrationally excited states of ground state
molecular nitrogen of molecular nitrogen N2(X 1∑g+,v) [3]. The afterglow regime is
described by the temporal relaxation of all heavy species, discarding the role of electron
impact collisions [4].
Modelling simulations show that the production of N(4S) and O(3P) atoms, as well as
NO(X) molecules is governed by an important interplay between mechanisms N2(X, v ≥ 13)
+ O → NO(X) + N(4S) and NO(X) + N(4S) →N2(X, v~3) + O for pulse durations longer than
1 ms, with an important contribution from N(2D) + O2 → NO(X) + O and N2(A) + O →
NO(X) + N(2D) reactions for shorter times. These predictions include the important
interdependence between most of the reaction rate coefficients and the gas temperature,
namely in what concerns the highly exothermic process NO(X) + N(4S) →N2(X, v~3) + O
(~2.45 eV), by solving at the same time the gas thermal balance equation.
This work was partially supported by the Portuguese FCT Fundação para a Ciência e a Tecnologia, under
Project UID/FIS/50010/2013.
[1] A. Rousseau, A. Dantier, L. Gatilova, Y. Ionikh, J. Röpcke, Y.Tolmachev Plasma Sources Sci. Technol. 14
(2005) 70
[2] Y. Ionikh, A. V. Meshchanov, J. Röpcke , A. Rousseau 322 (2006) Chem. Phys. 411–22
[3] C.D. Pintassilgo, O. Guaitella, A. Rousseau Plasma Sources Sci. Technol. 18 (2009) 025005
[4] C.D. Pintassilgo, V. Guerra, O. Guaitella and A. Rousseau Plasma Sources Sci. Technol. 19 (2010) 055001
