Computational Atomic and Molecular Physics for Transport Modeling of Fusion Plasmas

M S Pindzola¹ , F J Robicheaux¹ , S D Loch¹ , D C Griffin² , C P Balance² , D R Schultz³ , T Minami³ , J T Hogan³ , N R Badnell⁴ , A D Whiteford⁴ , M G O'Mullane⁴ , H P Summers⁴ , K Berrington⁵ , J Colgan⁶ , C J Fontes⁶ , T E Evans⁷ and D Stotler⁸

¹Auburn University, ²Rollins College, ³ORNL, ⁴University of Strathclyde, ⁵Sheffield Hallam University, ⁶LANL, ⁷DIII-D National Fusion Facility, ⁸PPPL

Summary

1. ITER Relevant Modeling Efforts

Experimental efforts are underway worldwide to provide scientific input needed for critical design decisions and for estimating the future performance of ITER. In particular, the final choice of material for the active plasma-facing materials in ITER presents an urgent need for reliable atomic data which are lacking, at present, in a number of key areas. These data provide the chief experimental tool for diagnosing the plasma-wall interaction in present machines.

Previous large-scale atomic collision calculations, through their interface with the ADAS collisional-radiative codes, are now widely used in present fusion-related modeling and diagnostic applications. ADAS-derived atomic data are used in the SANCO and UTC core impurity transport codes at JET. These data also represent the main source of atomic data for the SOLPS (also known as b2-Eirene) suite of divertor transport codes, developed by IPP-Garching and used for analysis of JET, Asdex-Upgrade, DIII-D, Tore Supra and Alcator C-Mod edge and divertor experiments.

2. Derived Atomic Data

A transport code's ability to determine the stage of ionization of an element at a particular location in a fusion plasma requires knowledge of generalized collisional radiative (GCR) coefficients, while the ability to determine the light emitted by an element across all ionization stages requires knowledge of total radiated power loss (RPL) coefficients, as supplied by ADAS. In the last year, collisional-radiative calculations have been completed for Li plasmas comparing the ADAS and Los Alamos suite of codes[1]. Work is in progress on further ADAS collisional-radiative calculations, using recent He, Li, and Be electron-ion scattering data, to generate temperature and density dependent GCR and RPL coefficients for ground and metastable states of every ionization stage. Dielectronic recombination data for dynamic finite density plasmas has been generated for an extensive set of laboratory and astrophysically abundant elements in the Li, Be, B, C, and O isoelectronic sequences [2]. Work is in progress on further first and second row periodic table isoelectronic sequences.

Our ability to generate accurate atomic data for electron-atom excitation, ionization, and recombination, as well as ion-atom excitation, charge-transfer, and ionization is based on the development of non-perturbative scattering theory over the last decade. All of the associated computer codes have been adapted for use on massively parallel architectures, and in the case of high Z atoms remain limited only by the size of current machines. Over the years we have also developed a suite of computer codes based on first-order perturbation scattering theory. For application to moderate to highly charged atomic ions, perturbative distorted-wave cross sections can be quite accurate. We are now adapting those codes for use on massively parallel architectures, especially in the case of high Z atoms. In the last year, 2D lattice time-dependent close-coupling calculations have been completed for the electron-impact excitation and ionization of He⁺[3], the electron-impact excitation of Li to high principal quantum numbers[4], and for the electron-impact ionization of all ionization stages of Be[5]. Work is in progress for elastic and inelastic e + H collisions and for the electron-impact ionization of C²⁺ in both the ground and metastable excited states. Large-scale R-matrix with pseudo-states (RMPS) calculations have been completed for electron-impact excitation of He [6], Li⁺[7], B⁺[8], C²⁺[9], and various light hydrogenic ions [10], as well as excitation and ionization of all ionization stages of Be[5,11]. We are now in the process of performing calculations of the electron-impact excitation of B, C⁺ , and Ne, as well as ionization of H-like and He-like atomic ions of fusion interest. Configuration-average distorted-wave calculations have been completed for the electron-impact ionization of several ionization stages of O[12]. Calculations of the electron-impact ionization of all ionization stages of W are now being performed. Intermediate-coupling distorted-wave calculations have been completed for the dielectronic and trielectronic recombination of Cl¹³⁺[13]. Time-dependent semi-classical lattice calculations have been completed for laser modified charge transfer processes in p + Li collisions [14], and calculations of charge transfer processes in σ + H, Be⁴⁺ + H, and proton collisions with excited H and are now being performed.

Non-perturbative scattering theory and the associated computer codes can be easily adapted for the advancement of science in other areas. At the same time, other applications provide valuable checks on the accuracy of the general methods. 2D time-dependent close-coupling calculations have been completed for double photoionization of He in excited states [15]. 3D time-dependent close-coupling calculations have been completed for double photoionization with excitation and triple photoionization of Li[16]. 2D time-dependent close-coupling calculations have been completed for the single, double, and triple photon ionization of [17]. Time-dependent lattice calculations have been completed to determine collective modes of ground and dark soliton states of Bose-Einstein condensates in anisotropic traps[18].

The references can be found on our web page. http://www.atomic.physics.auburn.edu

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