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 X-ray spectra of the Fe-L complex

2020 ◽  
Vol 641 ◽  
pp. A93
Author(s):  
Liyi Gu ◽  
Chintan Shah ◽  
Junjie Mao ◽  
Ton Raassen ◽  
Jelle de Plaa ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Impact ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Physical Parameters ◽  
Laboratory Measurements ◽  
X Ray

The Hitomi results for the Perseus cluster have shown that accurate atomic models are essential to the success of X-ray spectroscopic missions and just as important as the store of knowledge on instrumental calibration and astrophysical modeling. Preparing the models requires a multifaceted approach, including theoretical calculations, laboratory measurements, and calibration using real observations. In a previous paper, we presented a calculation of the electron impact cross sections on the transitions forming the Fe-L complex. In the present work, we systematically tested the calculation against cross-sections of ions measured in an electron beam ion trap experiment. A two-dimensional analysis in the electron beam energies and X-ray photon energies was utilized to disentangle radiative channels following dielectronic recombination, direct electron-impact excitation, and resonant excitation processes in the experimental data. The data calibrated through laboratory measurements were further fed into a global modeling of the Chandra grating spectrum of Capella. We investigated and compared the fit quality, as well as the sensitivity of the derived physical parameters to the underlying atomic data and the astrophysical plasma modeling. We further list the potential areas of disagreement between the observations and the present calculations, which, in turn, calls for renewed efforts with regard to theoretical calculations and targeted laboratory measurements.

scholarly journals Atomic Processes in Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 325-334
Author(s):  
Sultana N. Nahar
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Transition Probabilities ◽  
Central Star ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Theoretical Treatment ◽  
Atomic Processes ◽  
Ion Recombination

A hot central star illuminating the surrounding ionized H II region usually produces very rich atomic spectra resulting from basic atomic processes: photoionization, electron-ion recombination, bound-bound radiative transitions, and collisional excitation of ions. Precise diagnostics of nebular spectra depend on accurate atomic parameters for these processes. Latest developments in theoretical computations are described, especially under two international collaborations known as the Opacity Project (OP) and the Iron Project (IP), that have yielded accurate and large-scale data for photoionization cross sections, transition probabilities, and collision strengths for electron impact excitation of most astrophysically abundant ions. As an extension of the two projects, a self-consistent and unified theoretical treatment of photoionization and electron-ion recombination has been developed where both the radiative and the dielectronic recombination processes are considered in an unified manner. Results from the Ohio State atomic-astrophysics group, and from the OP and IP collaborations, are presented. A description of the electronic web-interactive database, TIPTOPBASE, with the OP and the IP data, and a compilation of recommended data for effective collision strengths, is given.

scholarly journals A brief review of the intensity of lines 3C and 3D in neon-like Fe XVII

2008 ◽  
Vol 86 (1) ◽  
pp. 199-208 ◽  
Author(s):  
G V Brown
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Ion Trap ◽  
Diagnostic Utility ◽  
The Sun ◽  
Model Calculations ◽  
Atomic Theory ◽  
X Ray ◽  
Electron Beam Ion Trap ◽  
Intercombination Line

X-ray emission from neon-like Fe XVII has been measured with high-resolution spectrometers from laboratory or celestial sources for nearly seven decades. Two of the strongest lines regularly identified in these spectra are the 1P1 → 1S0 resonance and the 3D1 → 1S0 intercombination line, known as 3C and 3D, respectively. This paper gives a brief overview of measurements of the intensities of the lines 3C and 3D from laboratory and celestial sources and their comparison to model calculations, with an emphasis on measurements completed using an electron beam ion trap. It includes a discussion of the measured absolute cross sections compared with results from modern atomic theory calculations as well as the diagnostic utility of the relative intensity, R = I3C/I3CD, as it applies to the interpretation of spectra measured from the Sun and extra-solar sources. PACS Nos.: 32.30.Rj, 32.30.–r, 32.70.Cs, 52.72.+v, 95.85.Nv, 96.60.P–, 97.10.Ex

scholarly journals Comment on electron-impact excitation cross section measurements for He-like xenon

2019 ◽  
Vol 97 (5) ◽  
pp. 576-578
Author(s):  
J.-C. Pain ◽  
M. Comet ◽  
C.J. Fontes
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ion Trap ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Experimental Investigations ◽  
State University ◽  
Electron Beam Ion Trap ◽  
Penn State ◽  
Experimental Values

We discuss lower-than-predicted collisional–excitation cross sections for helium-like xenon measured at an Electron Beam Ion Trap facility. In a review paper (H. Chen and P. Beiersdorfer. Can. J. Phys. 86, 55 (2008)), the authors find a significant effect due to the Breit interaction between the free and the bound electrons in the excitation process of He-like xenon. The authors state that the agreement between the measured and calculated cross section values can only be found when the generalized Breit interaction is included in the calculations. We have performed new calculations with a multi-configuration Dirac–Fock code, as well as with the Penn State University suite of codes, and our conclusions are that the contribution of the Breit interaction is much lower than found in the calculations presented in the abovementioned article. In fact, our predictions are subsequently almost twice as large as the experimental values. We present these considerations in hopes of motivating new experimental investigations.

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

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

Electron-impact excitation cross-section measurements at EBITs from 1986 to 2006

2008 ◽  
Vol 86 (1) ◽  
pp. 55-71 ◽  
Author(s):  
H Chen ◽  
P Beiersdorfer
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Ion Trap ◽  
Spectroscopic Properties ◽  
Highly Charged Ions ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Wide Range ◽  
Charged Ions

This paper reviews the electron-impact excitation (EIE) measurements at electron beam ion trap (EBIT) facilities in the last 20~years. EIE cross sections are important atomic parameters fundamental to understanding the spectroscopic properties of ions. The properties of an EBIT make it an ideal device to measure the EIE cross section of highly charged ions. As a matter of fact, a report of EIE measurement was among the first papers published on the first EBIT ever built, EBIT-I. Since then, a wide range of measurements have been performed for K-shell and L-shell highly charged ions of Ti, V, Cr, Mn, Fe, Xe, and Ba using a combination of crystal spectrometers and solid-state X-ray detectors. In the last few years, the measurements were extended to all strong Fe L-shell lines by using a 6 × 6 pixel array microcalorimeter.PACS Nos.: 32.30.Jc, 32.30.Rj, 34.50.Fa, 32.70.Cs

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
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