Elastic, diffusion, and viscosity cross sections for collisions involving excited atomic hydrogen

Collision Integrals for Interactions Involving Atoms in Electronically Excited States

“…In the phenomenological potential eq 6 the charge, q, is assumed to depend on the principal quantum number, n, In considering highly excited states, the polarizability value has been estimated as an average value over quantum sublevels by using the formula proposed by Hey 42 while the effective charge increases up to the limit of H + -H + interaction; that is, q ) 1. In Figure 5, the diffusion-type collision integrals obtained in the frame of the phenomenological approach are reported for 2 e n e 5 and compared with results by Celiberto et al 16 As can be appreciated, the method satisfactorily reproduces the increase in the Ω value due to the electronic excitation of the collision partners. Actually, the agreement is better at higher temperatures in a coulomb repulsive regime with percentage relative errors below 10% for n > 2 for T > 13 000, whereas in the low-temperature region discrepancies up to 25% are found.…”

“…The paper by Celiberto et al 16 has the great merit of investigating the collision integral dependence on the principal quantum number in symmetric collisions H(n)-H(n) up to n ) 2) interaction as a function of temperature as compared with results in the literature: (s) present multipotential approach, (---) multipotential approach by Capitelliand Lamanna 15 and by Celiberto et al 16 ([). Results of the phenomenological approach are also reported ( 5.…”

“…For hydrogen, a database of transport cross sections has been created by using scaling relations or extrapolation formulas fitting available excited-state calculations. 15,16 The derivation of complete and internally consistent data set of collision integrals for excited species is strongly hindered, within a traditional calculation scheme, by the need for accurate potential energy curves for the multiplicity of electronic terms correlating with species in a specific quantic state. This is already a challenging problem, since in the combination of orbital and spin angular momenta, a multiplicity of states arise, whose potential energy curves are largely unknown.…”

Estimation of higher-order contribution to viscosity of hydrogen plasmas including electronically excited states

“…[1][2][3][4] The transport coefficients of hydrogen plasma have been usually evaluated by using the first approximation of the Chapman-Enskog method 5 and have shown a strong dependence on the presence of electronically excited states especially at high pressures. [1][2][3][4] The transport coefficients of hydrogen plasma have been usually evaluated by using the first approximation of the Chapman-Enskog method 5 and have shown a strong dependence on the presence of electronically excited states especially at high pressures.…”

Molecular physics and kinetics of high-temperature planetary atmospheres

“…The reliability of the ground-state approximation, underlying the cited approaches, is however controversial. In fact, it has been proved that transport properties of atomic hydrogen plasma in thermodynamic equilibrium are affected by a proper account of electronically excited states with the estimated dependency of transport cross-sections on the quantum state (Capitelli and Lamanna 1974;Celiberto et al 1998;Laricchiuta et al 2009b) of interacting chemical species (Capitelli et al 2004;Bruno et al 2007a, b) and non-equilibrium conditions are expected to amplify these effects.…”