1,721,011 research outputs found
Electron-Molecule Cross Sections for Plasma Applications: The Role of Internal Energy of the Target
No full textThe role of internal excitation in affecting electron-molecule cross sections is analyzed fo H2, N2 and O2 systems. Particular emphasisi is given to the role of vibrational energy in affecting both the resonant and non-resonant electron molecule cross sections. In general for resonant transitions the cross sections dramatically depend on the nitial vibrational quantum number of the target, while a minor effect is found for direct (non-resonant) transtions. Cross sections in this last case reflect the form of Franck-Condon factors and Franck-Condon densities linking the relevant bound-bound or bound-continuum transitions. A similar behaviour is presented when the target is electronically excited. In this case, however, the enhancement of cross section is much higher
Plasma Science for Aerospace and Thermonuclear Fusion Applications
No full textTheoretical applications of plasma science to space and thermonuclear fusion technologies is illustrated. In particular, the role of molecular non equilibrium plasmas in problems arising in re-entry conditions of space vehicles impacting on the atmosphere of a planet, in space explorations, and low temperature processes occurring in nuclear fusion tokamaks, is discussed. Particular emphasis is placed on the link between elementary processes occurring in the plasma at the microscopic level and the macroscopic behavior. In particular, recent results on cross section calculations for resonant electron-molecule collisions, involving N2, O2 and H2 molecules, are presented along with an application to the temporal evolution of a nitrogen plasma toward the thermal equilibrium
The dependence of electron impact excitation and ionization cross sections of H2 and D2 molecules on vibrational qunatum number
No full textElectron-molecule collision processes in non-equilibrium molecular plasmas
No full textThe role of internal degrees of freedom of molecular species in non-equilibrium plasmas is briefly
outlined. Importance of collision cross sections for electron-impact with excited molecules in kinetic
models is discussed, and few examples of some particular process in real plasma systems is
illustrated. Some preliminary results of vibrational excitations by electron impact are shown
Electron collisions with excited molecules in low temperature plasmas
Full text linkState-to-state vibrationally resolved cross sections for electron-impact processes
involving vibrationally excited molecules are reviewed, with particular emphasis on
atmospheric and fusion plasma applications
State-to-state electron impact cross sections for BeH+ molecular ions in ITER-like fusion edge plasmas with Be walls
No full textBeH+ molecules will be an important intermediary species present in fusion plasmas with Be walls (e.g. JET, ITER), both for impurity transport and spectroscopic studies. To enable such analyses the electron-impact-induced excitations X (1)Sigma(+)(v(i)) -> A (1)Sigma(+)(v(f)) and X (1)Sigma(+)(v(i)) -> B (1)Pi (v(f)) in BeH+(v(i)) molecular ion, occurring between the v(i) and v(f) vibrational levels of different electronic states (vibro-electronic transitions), have been studied using the Coulomb-Born approximation. The cross sections and rate coefficients for these transitions have been calculated in a broad energy and temperature range, respectively. Accurate analytic fit expressions have been derived for the cross sections and rate coefficients for the v(i) = v(f) = 0 case of considered electronic transitions that have correct asymptotic limits. It has been demonstrated that the cross sections and rate coefficients for v(i), v(f) > 0 transitions satisfy approximate (to within 10%) scaling relationships that involve the transition energies and matrix elements of dipole transition moments only
Equivalent Initial Conditions in the Study of Chemical Equilibrium: The Stoichiometric and Thermodynamic Points of View
No full textConsiders the existence of an infinite number of initial conditions that, at given temperature T and pressure p, lead to the same equilibrium compositio
Resonant vibrational-excitation cross sections and rate constants for low-energy electron scattering by molecular oxygen
No full textResonant vibrational-excitation cross sections and rate constants for electron scattering by molecular oxygen are presented. Transitions between all 42 vibrational levels of O2(X (3)Sigma(-)(g)) are considered. Molecular rotations are parametrized by the rotational quantum number J, which is considered in the range 1-151. The lowest four resonant states of O2(-), (2)Pi(g), (2)Pi(u), (4)Sigma(-)(u) and (2)Sigma(-)(u) are taken into account. The calculations are performed using the fixed-nuclei R-matrix approach to determine the resonance positions and widths, and the boomerang model to characterize the nuclei motion. Two energy regions below and above 4 eV are investigated: the first one is characterized by sharp structures in the cross section and the second by a broad resonance peaked at 10 eV. The computed cross sections are compared with theoretical and experimental results available in the literature for both energy regions, and are made available for use by modelers. The effect of including rotational motion is found to be non-negligible
Theoretical vibrational-excitation cross sections and rate coefficients for electron-impact resonant collisions involving rovibrationally excited N2 and NO molecules
No full textElectron-impact vibrational-excitation cross sections, involving rovibrationally excited N2 and NO molecules, are calculated for collisions occurring through the nitrogen resonant electronic state N2(-) (X (2)Pi(g)), and the three resonant states of nitric oxide NO(-)( (3)Sigma(-), (1)Delta, (1)Sigma(+)). Complete sets of cross sections have been obtained for all possible transitions involving 68 vibrational levels of N2 (X (1)Sigma(+)(g)) and 55 levels of NO(X (2)Pi), for incident electron energy between 0.1 and 10 eV. In order to study the rotational motion in the resonant processes, cross sections have also been computed for rotationally elastic transitions characterized by the rotational quantum number J running from 0 to 150. The calculations are performed within the framework of the local complex potential model, using potential energies and widths optimized to reproduce the experimental cross sections available in the literature. Rate coefficients are calculated for transitions between all vibrational levels by assuming a Maxwellian electron energy distribution function in the temperature range from 0.1 to 100 eV. All numerical data are available at http://users.ba.cnr.it/imip/cscpal38/phys4entry/database.htm
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