J. Colgan

Dielectronic Recombination Data for Dynamic Finite-Density Plasmas. I; Goals and Methodology

A programme is outlined for the assembly of a comprehensive dielectronic recombination database within the generalized collisional-radiative (GCR) framework. It is valid for modelling ions of elements in dynamic finite-density plasmas such as occur in transient astrophysical plasmas such as solar flares and in the divertors and high transport regions of magnetic fusion devices. The resolution and precision of the data are tuned to spectral analysis and so are sufficient for prediction of the dielectronic recombination contributions to individual spectral line emissivities. The fundamental data are structured according to the format prescriptions of the Atomic Data and Analysis Structure (ADAS) and the production of relevant GCR derived data for application is described and implemented following ADAS. The requirements on the dielectronic recombination database are reviewed and the new data are placed in context and evaluated with respect to older and more approximate treatments. Illustrative results validate the new high-resolution zero-density dielectronic recombination data in comparison with measurements made in heavy-ion storage rings utilizing an electron cooler. We also exemplify the role of the dielectronic data on GCR coefficient behaviour for some representative light and medium weight elements.

Dielectronic recombination data for dynamic finite-density plasmas III. The beryllium isoelectronic sequence

Dielectronic recombination data for the beryllium isoelectronic sequence has been calculated as part of the assembly of a dielectronic recombination database necessary for modelling of dynamic finite-density plasmas (Badnell et al. 2003, A&A, 406, 1151). Dielectronic recombination coecients for a selection of ions from this sequence are presented and the results discussed.

Dielectronic recombination data for dynamic finite-density plasmas VI. The boron isoelectronic sequence

We have calculated dielectronic recombination rate coefficients for 22 ions of the boron isoelectronic sequence, between C+ and Xe49+, within the generalized collisional-radiative framework, as outlined by Badnell et al. (2003). Calculations have been performed from both ground and metastable initial states, in both LS- and intermediate-coupling, allowing for Deltan = 0 and Deltan = 1 core-excitations. Results are presented and discussed for a selection of ions from the sequence. Results which are not presented here can be accessed from the Atomic Data and Analysis Structure (ADAS) database (Summers 2003) or from the Oak Ridge Controlled Fusion Atomic Data Center (http://www-cfadc.phy.ornl.gov). Comparison is made with the results of other existing theoretical calculations.

Dielectronic recombination data for dynamic finite-density plasmas V. The lithium isoelectronic sequence

Dielectronic recombination data for the lithium isoelectronic sequence has been calculated as part of the assembly of a dielectronic recombination database necessary for modelling of dynamic finite-density plasmas (Badnell et al. 2003). Dielectronic recombination coefficients for a selection of ions from this sequence are presented and the results discussed.

Fully quantal (γ, 2e) calculations for absolute differential cross sections of helium

The formulation of the time-dependent close-coupling method is extended so that energy and angle differential cross sections for the double photoionization of helium may be obtained. The fully quantal method now yields absolute total integral, energy differential, and angle differential cross sections. A detailed comparison is made with the absolute synchrotron measurements of Br?uning et al (1998 J. Phys. B: At. Mol. Opt. Phys. 31 5149-60) for triple differential cross sections at 20?eV excess photon energy. The agreement between theory and experiment is excellent.

Generalized collisional radiative model for light elements. Part B: Data for the Be isonuclear sequence

A first stage collision database is assembled which contains electron-impact effective collision strengths, and ionization and recombination rate coefficients for Li, Li+, and Li2+. The first stage database is constructed using the R-matrix with pseudo-states, time-dependent close-coupling, converged close-coupling, and perturbative distorted-wave methods. A second stage collision database is then assembled which contains generalized collisional-radiative and radiated power loss coefficients. The second stage database is constructed by solution of collisional-radiative equations in the quasi-static equilibrium approximation using the first stage database. Both collision database stages reside in electronic form at the ORNL Controlled Fusion Atomic Data Center and in the ADAS database, and are easily accessed over the worldwide internet.