Elastic and vibrationally inelastic slow collisions: H + H₂, H⁺+ H₂

Abstract

We report on a comprehensive study of the scattering of hydrogen atoms on the ground electronic surface of hydrogen molecules in the range of centre of mass energies 0.1-100 eV. Differential and integral elastic cross sections, the related transport cross sections, and vibrationally inelastic cross sections starting from both ground and excited vibrational states, are calculated using a fully quantal, coupled-channel approach in a truncated vibrational basis set, while the rotational dynamics of H 2 is treated with the infinite order sudden approximation prescription. For comparison and to highlight the major physical mechanisms revealed in these collisions, a parallel study is carried out for scattering of protons on hydrogen molecules.

Mass changes in NSTX surface layers with Li conditioning as measured by quartz microbalances

“…potential curves, using coupled cluster singles-doubles-triplesquadruples (CCSDTQ) method with unrestricted Hartree-Fock [15], equivalent to the full configuration interaction for 4 electron systems, and are in good agreement with the full valence CI calculations of Boutalib et al [16]. Fully quantum-mechanical calculations of the cross sections, convergent in partial waves, were performed in the range 10 -4 -0.12 eV, using Johnson method of logarithmic derivatives [17,18] and applying plane-wave boundary conditions for nuclear motion at R max =100 Bohrs. The singlet and triplet potentials were smoothly matched to the asymptotic Van der Walls form [19].…”

“…The momentum transfer cross section of lithium on molecular deuterium was estimated from Li+D cross section using analogy with comparison of fully quantal results of H+D and H+D 2 in refs. [17,18]. The mean free path of Li at 627 °C in 1 mtorr of molecular deuterium at 27 °C is estimated to be 7.7…”

Improved elastic collision modeling in DEGAS 2 for low-temperature plasmas

“…20 At the divertor throat, electron temperatures are T e ϳ40 eV, while T e ϳ1 -2 eV throughout much of the divertor. In regions of high density and low temperature, areas of intense localized recombination form, increasing the neutral density within the divertor.…”

Mean free paths and elastic and related transport cross sections for neutrals and singly charged ions of Li, Be, and B in hydrogen plasmas

“…The QM approach 13,14,16,19,22,25 is based on the solution of the radial Schrödinger equation for each relevant partial wave ͑angular momentum͒ component on the adiabatic quasimolecular state potential energy curve of the systems under consideration, namely ͑LiH͒ + , ͑BeH͒ + , ͑BH͒ + , and LiH. These curves evolve from the relevant A + +H, A +H + , or Li+H states ͑A =Li,Be,B͒, at large internuclear separations.…”