The role of radiative reabsorption on the electron energy distribution functions in H2/He plasma expansion through a tapered nozzle

2014 ◽  
Vol 21 (9) ◽  
pp. 093508 ◽  
Author(s):  
Giuliano D'Ammando ◽  
Mario Capitelli ◽  
Fabrizio Esposito ◽  
Annarita Laricchiuta ◽  
Lucia D. Pietanza ◽  
...  
1986 ◽  
Vol 68 ◽  
Author(s):  
M. Dilonardo ◽  
M. Capitelli ◽  
R. Winkler ◽  
J. Wilhelm

AbstractElectron energy distribution functions in molecular rf plasmas (CO, SF6) have been calculated by numerically solving the time dependent Boltzmann equation in a wide range of field frequencies up to the establishment of the periodic state.Particular attention is given to the reduction of the modulation degree and phase shift with respect to the rf field of the isotropic distribution function and of some macroscopic quantities as a function of frequency.Time averages of distribution functions and of some macroscopic quantities are then compared with the corresponding results obtained by using the effective field approximation.Finally we discuss the role of the second kind collisions in affecting the results.


1979 ◽  
Vol 34 (5) ◽  
pp. 585-593 ◽  
Author(s):  
M. Capitelli ◽  
M. Dilonardo

Abstract Electron energy distribution functions (EDF) of molecular H2 have been calculated by numerically solving the Boltzmann equation including all the inelastic processes with the addition of superelastic vibrational collisions and of the hydrogen atoms coming from the dissociation process. The population densities of the vibrational levels have been obtained both by assuming a Boltz-mann population at a vibrational temperature different from the translational one and by solving a system of vibrational master equations coupled to the Boltzmann equation. The results, which have been compared with those corresponding to a vibrationally cold molecular gas, show that the inclusion of superelastic collisions and of the parent atoms affects the EDF tails without strongly modifying the EDF bulk. As a consequence the quantities affected by the EDF bulk, such as average and characteristic energies, drift velocity, 0-1 vibrational excitation rate are not too much affected by the inclusion of superelastic vibrational collisions and of parent atoms, while a strong influence is observed on the dissociation and ionization rate coefficients which depend on the EDF tail. Calculated dissociation rates, obtained by EDF's which take into account both the presence of vibrationally excited molecules and hydrogen atoms, are in satisfactory agreement with experimental results.


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