Collisions superelastic

With energy conservation, E. = Ej.+ (Sj.- e )=E + ethe cross section for superelastic collisions E > Ep... 

Superelastic collision. A collision that increases the translational energy of the fast-moving collision partner. 

Here, e and e represent slow and fast electrons, respectively, and the superelastic collision may preferentially produce the A resonant excited state because A — A is a strong dipole transition. (Note that inelastic cross sections for electron-atom collisions are generally larger for dipole-allowed transitions compared to dipole-forbidden transitions.) Since the ground state density N is high, the electron excitation of A following Eq. (7) is fast ... 

It was mentioned in Section III that cools vibrationally in storage rings on time scales much shorter than the radiative vibrational lifetimes. The effect was shown to be correlated with the interaction of the stored ion beam with the electron beam, and it was concluded that since higher vibrational levels recombine faster than lower levels, there will be an increase of the relative population of lower vibrational levels as a function of time. More recent work has shown that superelastic collisions... 

The rate coefficient ei.excit. is expressed in cm /s E is the electric field strength, in V/cm and no is gas density in 1/cm. Numerical values of the parameters C and C2 for different electronically excited states (and ionization) of CO2 and N2 are presented in Table 2-18. If the level of vibrational excitation is high, superelastic collisions provide higher electron energies and faster electronic excitation at the same value of E/no. This can be taken into account by adding terms related to vibrational temperature Tv(in K) ... 

Relaxation of electronically excited atoms and molecules is due to different mechanisms. Superelastic collisions (energy transfer back to plasma electrons) and radiation are essential mostly in thermal plasma. Relaxation in collision with other heavy particles dominates in non-thermal discharges. Relaxation of electronic excitation into translational degrees... 

When the plasma ionization degree exceeds 10 the electronic excitation transfer can be effectively provided via interaction with an electron gas. These relaxation processes are due to superelastic collisions and are conventional for thermal plasma conditions. 

Scattering of electrons, fast atoms, or ions with laser-excited atoms A can result in elastic, inelastic, or superelastic collisions. In the latter case, the excitation energy of A is partly converted into kinetic energy of the scattered particles. Orientation of the excited atoms by optical pumping with polarized lasers allows investigations of the influence of the atomic orientation on the differential cross sections for A + B collisions, which differs for collisions with electrons or ions from the case of neutral... 

In the present analysis, the EEDF is determined by solving the Boltzmann equation as a fimction of the reduced electric field E/N so that the electron mean energy equals 3/2 times the electron temperature experimentally measured by the probe. The Boltzmann equation is simultaneously solved with the master equations for the vibrational distribution function (VDF) of the N2 X iZg+ state, since the EEDF of N2-based plasma is strongly affected by the VDF of N2 molecules owing to superelastic collisions with vibrationally excited N2 molecules. A more detailed account of obtaining the EEDF is given in the next section. 

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