Analog and digital simulations of Maxwellian plasmas forastrophysics

2008 ◽  
Vol 86 (1) ◽  
pp. 209-216 ◽  
Author(s):  
D W Savin ◽  
N R Badnell ◽  
P Beiersdorfer ◽  
B R Beck ◽  
G V Brown ◽  
...  
Keyword(s):  
Electron Impact ◽  
Impact Ionization ◽  
Ion Trap ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Fractional Abundance ◽  
Collisional Ionization ◽  
Ionization Balance

Many astrophysical and laboratory plasmas possess Maxwell–Boltzmann (MB) electron energy distributions (EEDs). Interpreting or predicting the properties of these plasmas requires accurate knowledge of atomic processes such as radiative lifetimes, electron impact excitation and de-excitation, electron impact ionization, radiative recombination, dielectronic recombination, and charge transfer, all for thousands of levels or more. Plasma models cannot include all of the needed levels and atomic data. Hence, approximations need to be made to make the models tractable. Here we report on an “analog” technique we have developed for simulating a Maxwellian EED using an electron beam ion trap and review some recent results using this method. A subset of the atomic data needed for modeling Maxwellian plasmas relates to calculating the ionization balance. Accurate fractional abundance calculations for the different ionization stages of the various elements in the plasma are needed to reliably interpret or predict the properties of the gas. However, much of the atomic data needed for these calculations have not been generated using modern theoretical methods and are often highly suspect. Here we will also review our recent updating of the recommended atomic data for “digital’ computer simulations of MB plasmas in collisional ionization equilibrium (CIE), describe the changes relative to previously recommended CIE calculations, and discuss what further recombination and ionization data are needed to improve this latest set of recommended CIE calculations. PACS Nos.: 34.70.+e,34.80.Dp, 34.80.Kw, 34,80,Lx, 52.50.–j, 52.20.Fs, 52.20.Hv, 52.25.Jm, 52,72.+v, 52.75.–d, 95.30.Dr, 95.30.Ky, 98.38.Bn, 98.58.Bz

EXPERIMENTS ON ELECTRON IMPACT EXCITATION AND DIELECTRONIC RECOMBINATION AT HARVARD-SMITHSONIAN

1989 ◽  
Vol 50 (C1) ◽  
pp. C1-405-C1-409
Author(s):  
L. D. GARDNER ◽  
J. L. KOHL ◽  
D. W. SAVIN ◽  
A. R. YOUNG
Keyword(s):  
Electron Impact ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation

scholarly journals Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions

Atoms ◽  
2015 ◽  
Vol 3 (4) ◽  
pp. 474-494 ◽  
Author(s):  
Zhongwen Wu ◽  
Yanbiao Fu ◽  
Xiaoyun Ma ◽  
Maijuan Li ◽  
Luyou Xie ◽  
...  
Keyword(s):  
Electron Impact ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation

scholarly journals Cross Sections for Electron Impact Excitation of O VI Lines

2011 ◽  
Vol 20 (4) ◽  
Author(s):  
Haykel Elabidi ◽  
Sylvie Sahal-Bréchot ◽  
Nébil Ben Nessib
Keyword(s):  
Fine Structure ◽  
Electron Impact ◽  
Cross Sections ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Excitation Cross Sections

AbstractRadiative atomic data and electron impact excitation cross sections for the 2s-2p transitions in O VI for transitions among the fine structure levels belonging to the 1s

Electron–ion interactions for trapped highly charged Ge ions

2006 ◽  
Vol 84 (1) ◽  
pp. 67-81 ◽  
Author(s):  
G Machtoub ◽  
J.R. Crespo López-Urrutia ◽  
X Zhang ◽  
H Tawara
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Ion Trap ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Theoretical Simulation ◽  
X Ray ◽  
New Information ◽  
Excitation Processes

A theoretical simulation of complex K X-ray spectra including those from dielectronic recombination and excitation processes is presented for trapped highly charged germanium ions ( Geq+, q = 27–30) interacting with a dense electron beam. We carried out numerical calculations of transition rates, level energies, transition wavelengths, resonance and collision strengths, and satellite intensity factors. Analytical results related to cross sections of B- through He-like Ge ions were obtained as well. The simulated spectra, including the contribution from different charge states of Ge27+–Ge30+, show good overall agreement over a wide electron energy range with the available X-ray measurements from the Heidelberg electron beam ion trap (EBIT). We have also predicted the electron impact excitation cross-section ratios for different transitions of Ge29+ and Ge30+ ions. It should be emphasized that the present analysis can also provide new information and clues of possible temperature measurements for EBIT and other plasma diagnostics.PACS No.: 32.30.Rj

scholarly journals R-matrix electron-impact excitation data for the N-like iso-electronic sequence

2020 ◽  
Vol 643 ◽  
pp. A95
Author(s):  
Junjie Mao ◽  
N. R. Badnell ◽  
G. Del Zanna
Keyword(s):  
Electron Impact ◽  
Plasma Diagnostics ◽  
Spectral Lines ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Astrophysical Plasma ◽  
Wide Range ◽  
The Impact ◽  
Effective Collision

Context. Spectral lines from N-like ions can be used to measure the temperature and density of various types of astrophysical plasmas. The atomic databases of astrophysical plasma modelling codes still have room for improvement in their electron-impact excitation data sets for N-like ions, especially for R-matrix data. This is particularly relevant for future observatories (e.g. Arcus), which will host high-resolution spectrometers. Aims. We aim to obtain level-resolved effective collision strengths for all transitions up to nl = 5d over a wide range of temperatures for N-like ions from O II to Zn XXIV (i.e. O+ to Zn23+) and to assess the accuracy of the present work. We also examine the impact of our new data on plasma diagnostics by modelling solar observations with CHIANTI. Methods. We carried out systematic R-matrix calculations for N-like ions, which included 725 fine-structure target levels in both the configuration interaction target and close-coupling collision expansions. The R-matrix intermediate coupling frame transformation method was used to calculate the collision strengths, while the AUTOSTRUCTURE code was used for the atomic structures. Results. We compare the present results for selected ions with those in archival databases and the literature. The comparison covers energy levels, oscillator strengths, and effective collision strengths. We show examples of improved plasma diagnostics when compared to CHIANTI models, which use only distorted wave data as well as some using previous R-matrix data. The electron-impact excitation data are archived according to the Atomic Data and Analysis Structure (ADAS) data class adf04 and will be available in OPEN-ADAS. The data can be used to improve the atomic databases for astrophysical plasma diagnostics.

Resonant electron impact excitation of highly charged Fe ions studied with a compact electron beam ion trap

2020 ◽  
Vol 49 (4) ◽  
pp. 511-514 ◽  
Author(s):  
Masashi Monobe ◽  
Hiroyuki A. Sakaue ◽  
Daiji Kato ◽  
Izumi Murakami ◽  
Hirohisa Hara ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Impact ◽  
Ion Trap ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Electron Beam Ion Trap ◽  
Resonant Electron ◽  
Fe Ions

scholarly journals R-matrix electron-impact excitation data for the C-like iso-electronic sequence

2020 ◽  
Vol 634 ◽  
pp. A7 ◽  
Author(s):  
J. Mao ◽  
N. R. Badnell ◽  
G. Del Zanna
Keyword(s):  
Electron Impact ◽  
Energy Levels ◽  
Transformation Method ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Astrophysical Plasmas ◽  
Close Coupling ◽  
The Impact ◽  
Effective Collision

Context. Emission and absorption features from C-like ions serve as temperature and density diagnostics of astrophysical plasmas. R-matrix electron-impact excitation data sets for C-like ions in the literature merely cover a few ions, and often only for the ground configuration. Aims. Our goal is to obtain level-resolved effective collision strength over a wide temperature range for C-like ions from N II to Kr XXXI (i.e., N+ to Kr30+) with a systematic set of R-matrix calculations. We also aim to assess their accuracy. Methods. For each ion, we included a total of 590 fine-structure levels in both the configuration interaction target and close-coupling collision expansion. These levels arise from 24 configurations 2l3nl′ with n = 2−4, l = 0−1, and l′ = 0−3 plus the three configurations 2s22p5l with l = 0−2. The AUTOSTRUCTURE code was used to calculate the target structure. Additionally, the R-matrix intermediate coupling frame transformation method was used to calculate the collision strengths. Results. We compare the present results of selected ions with archival databases and results in the literature. The comparison covers energy levels, transition rates, and effective collision strengths. We illustrate the impact of using the present results on an Ar XIII density diagnostic for the solar corona. The electron-impact excitation data is archived according to the Atomic Data and Analysis Structure (ADAS) data class adf04 and will be available in OPEN-ADAS. The data will be incorporated into spectral codes, such as CHIANTI and SPEX, for plasma diagnostics.

Sign in / Sign up

Export Citation Format

Share Document