Final Report on Atomic Database Project

Yuan, J., Gui, Z., and Moses, G.A.

University of Wisconsin--Madison

关键词: Thermonuclear Reactors;    70 Plasma Physics And Fusion Technology;    Naval Research Laboratory;    Atoms;    74 Atomic And Molecular Physics;   

DOI  :  10.2172/897651
RP-ID  :  DOE/ER/54576-1
RP-ID  :  FG02-00ER54576
RP-ID  :  897651

美国|英语

来源: UNT Digital Library

【 摘 要 】

Atomic physics in hot dense plasmas is essential for understanding the radiative properties of plasmas either produced terrestrially such as in fusion energy research or in space such as the study of the core of the sun. Various kinds of atomic data are needed for spectrum analysis or for radiation hydrodynamics simulations. There are many atomic databases accessible publicly through the web, such as CHIANTI (an atomic database for spectroscopic diagnostics for astrophysical plasmas) from Naval Research Laboratory [1], collaborative development of TOPbase (The Opacity Project for astrophysically abundant elements) [2], NIST atomic spectra database from NIST [3], TOPS Opacities from Los Alamos National Laboratory [4], etc. Most of these databases are specific to astrophysics, which provide energy levels, oscillator strength f and photoionization cross sections for astrophysical elements ( Z=1-26). There are abundant spectrum data sources for spectral analysis of low Z elements. For opacities used for radiation transport, TOPS Opacities from LANL is the most valuable source. The database provides mixed opacities from element for H (Z=1) to Zn (Z=30) The data in TOPS Opacities is calculated by the code LEDCOP. In the Fusion Technology Institute, we also have developed several different models to calculate atomic data and opacities, such as the detailed term accounting model (DTA) and the unresolved transition array (UTA) model. We use the DTA model for low-Z materials since an enormous number of transitions need to be computed for medium or high-Z materials. For medium and high Z materials, we use the UTA model which simulates the enormous number of transitions by using a single line profile to represent a collection of transition arrays. These models have been implemented in our computing code JATBASE and RSSUTA. For plasma populations, two models are used in JATBASE, one is the local thermodynamic equilibrium (LTE) model and the second is the non-LTE model. For the LTE model, the calculation is simple since the Boltzmann distribution can be used. As long as we have the energy levels and the ionization energy, we can calculate the plasma population very easily. However, for the non-LTE model, the calculation is very complex since various atomic data are required to build the transition balance matrix. Currently, empirical formulas are used to calculate these data such as electron collision ionization and autoionization. Furnished with these tested atomic data computing codes, we have developed a friendly user interface and a flexible atomic database [5]. The UTA model is considered the most practical method for medium and high Z elements since it is very time-consuming and difficult to calculate the enormous number of the transitions. However, the UTA model may overestimate the opacity, therefore, the DTA model is desirable even for medium and high Z elements. With the constant decrease in the cost of the disk storage and increase of CPU speed, it is possible to apply the DTA model to the medium and high Z elements. In this project, we calculate opacities for high Z elements in fully detailed term accounting model for significant populated states. For the various rate coefficients, we calculate the data using the detailed configuration accounting approximation. In order to handle the large volume of data generated for medium to high-Z atoms, we use the HDF data format as our database format, which is becoming a standard for storing scientific data. We have built a sophisticated graphical user interface using Java technology to distinguish our atomic database from other existing databases. Unlike other atomic databases, in which the users can obtain the opacity data in a pair of photon energy and opacity, in our database the user can browser more detailed atomic data information other than the opacity data set by combining our atomic database and Java technology. For example, the user can find out the abundant ion stage and electron configuration state in a certain plasma condition by several clicks on the user interface.