No abstract available

[en] We review the calculational method of the lattice time-dependent Schroedinger equation (LTDSE) approach. Parallel computing implementation of LTDSE is also discussed. We apply the LTDSE approach here to collisions of Be⁴⁺ ions on hydrogen atoms and demonstrate how it can contribute to the goals of the Controlled Fusion Atomic Data Center. (author)

[en] Total and state-selective cross sections for charge transfer in ∼1-1000 keV/u He²⁺ + H collisions have been calculated using a variety of theoretical approaches, namely, the classical trajectory Monte Carlo, atomic-orbital close-coupling and lattice, time-dependent Schroedinger equation methods. Comparison of the results with available experimental measurements and other theoretical cross sections indicates the regimes in which each method is most reliable. The present cross sections here, and their evaluation in light of existing data, provide a new benchmark for this inelastic channel in the fundamental collision system He²⁺ + H over a wide range of collision energies and final quantum levels

[en] We propose a method to describe charge transfer in ion-atom collisions that hybridizes the lattice, time-dependent Schroedinger equation (LTDSE) approach with the atomic-orbital coupled-channel technique. This method takes advantage of the completeness of the treatment of the collision problem through the LTDSE approach within a relatively small space around the distance of closest approach during the collision. It then extends the solution into the asymptotic regime through the less computationally intensive continuation of the time evolution of the electronic states under consideration utilizing a small, external coupled-channels expansion. This method is employed to calculate coherence parameters of an electron captured into the n = 2 shell of hydrogen in H⁺+He collisions to illustrate its effectiveness. The results show excellent agreement with experimental measurements and constitute improvements over various existing theoretical treatments

[en] We present recent measurements of absolute electron-impact ionization cross sections for Be-like C III, N. IV, and O V forming Li-like C IV, N. V, and O VI. The measurements were taken using the crossed-beams apparatus at Oak Ridge National Laboratory. A gas cell beam attenuation method was used to independently measure the metastable fractions present in the ion beams. The measured ionization cross sections were compared with calculations using the R-matrix with pseudostates and distorted-wave theoretical methods. Best agreement is found with the R-matrix with pseudostates cross sections results that account for the metastable fractions inferred from the gas attenuation measurements. We present a set of recommended rate coefficients for electron-impact single ionization from the ground and metastable states of each ion

[en] Performance of the ITER is anticipated to be highly sensitive to the edge plasma condition. The edge pedestal in ITER needs to be predicted from an integrated simulation of the necessary first principles, multi-scale physics codes. The mission of the SciDAC Fusion Simulation Project (FSP) Prototype Center for Plasma Edge Simulation (CPES) is to deliver such a code integration framework by (1) building new kinetic codes XGC0 and XGC1, which can simulate the edge pedestal buildup; (2) using and improving the existing MHD codes ELITE, M3D-OMP, M3D-MPP and NIMROD, for study of large-scale edge instabilities called Edge Localized Modes (ELMs); and (3) integrating the codes into a framework using cutting-edge computer science technology. Collaborative effort among physics, computer science, and applied mathematics within CPES has created the first working version of the End-to-end Framework for Fusion Integrated Simulation (EFFIS), which can be used to study the pedestal-ELM cycles

[en] We present a joint theoretical and experimental study of the time evolution of electronic states of highly charged hydrogenic ions formed by capture during transmission through solids as they undergo multiple collisions and radiative decay. For this transport problem we have developed an inhomogeneous nonunitary Lindblad master equation that allows for a description of open quantum systems with both sinks (electron loss) and source (capture) present. We apply this theoretical framework to study transient coherences created in electron capture by 13.6 MeV/amu Ar¹⁸⁺ ions transmitted through amorphous carbon foils and decoherence during subsequent interaction with the foil. In the limit of thin targets we can directly probe electron capture cross sections under single collision conditions, while for thicker targets we follow the partially coherent dynamics of the open quantum system in interaction with the solid as a function of interaction time. The calculated results are in close agreement with experimental data obtained at the LISE facility in GANIL. Photon intensities from excited argon ions were determined through high resolution x-ray spectroscopy in which individual fine structure components were resolved. Measurements were performed for a wide range of carbon foil thickness to study the time development of the excited state populations