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in subjects: "Electron-Ion Collisions"

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Progress in collisions of multiply charged ions

The increasing power and availability of supercomputers during the last decade led to significant progress in the theory of multicharged ion interactions. However, important tests of many theoretical predictions were lacking, and have become possible only quite recently as new capabilities have been realized in the laboratory. This paper broadly surveys some of these experimental developments, and their impact on our understanding of collisional interactions of multicharged ions. The scope is l… more

Date: January 1, 1991

Creator: Phaneuf, R.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Nonlinear evolution of drift instabilities in the presence of collisions

Nonlinear evolution of drift instabilities in the presence of electron-ion collisions in a shear-free slab has been studied by using gyrokinetic particle simulation techniques as well as by solving, both numerically and analytically, model mode-coupling equations. The purpose of the investigation is to determine the mechanisms responsible for the nonlinear saturation of the instability and for the ensuing steady-state transport. Such an insight is very valuable for understanding drift wave prob… more

Date: July 1, 1986

Creator: Federici, J. F.; Lee, W. W. & Tang, W. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron impact ionization of N/sup 4 +/ and N/sup 5 +/

A new crossed beams apparatus for measuring absolute electron impact ionization cross-sections of multiply charged ions is described. First measurements are also reported which deal with N/sup 4 +/ and N/sup 5 +/. The results are in good agreements with those previously obtained by the Oak Ridge group. For N/sup 5 +/ a non negligible signal is observed below the ground state ionization threshold. It is attributed to the presence of ions in metastable states. From the semi-empirical Lotz formula… more

Date: January 1, 1984

Creator: Defrance, P.; Chantrenne, S.; Brouillard, F.; Rachafi, S.; Belic, D.; Jureta, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Analysis of electron transport in the plasma of thermionic converters

Electron transport coefficients of a gaseous ensemble are expressed analytically as function of density, and are expressed analytically as function of temperature up to an unknown function which has to be evaluated for each specific electron-neutral atom cross section. In order to complete the analytical temperature dependence one may introduce a polynomial expansion of the function or one may derive the temperature dependence of a set of coefficients, numbering thirteen for a third approximati… more

Date: March 1, 1980

Creator: Stoenescu, M.L. & Heinicke, P.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Multiphoton processes in scattering and ionization in an intense linearly-polarized radiation field

We have employed the Gavrila-Kaminski formulation for the conversion of the time-dependent Schrodinger equation to a set of coupled differential equations that describe the interaction of an electron with a proton in the presence of an intense linearly-polarized radiation field in the Kramers-Henneberger gauge. The differential equations are solved numerically by a linear algebraic prescription effectively applied to electron-molecule collisions. We studied both electron-proton collisions assis… more

Date: January 1, 1992

Creator: Collins, L.A. (Los Alamos National Lab., NM (United States)) & Csanak, G. (Tsukuba Univ., Ibaraki (Japan))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effects of low-energy-electron-capture collisions (H/sub 0/ + c/sup n+/) on the particle and energy balance of tokamak plasmas

To illustrate the way in which atomic data provides enlightenment in the search for understandable (and thus extrapolable) confinement models, we restrict our scope to electron capture collisions involving H/sub 0/ and multiply-charged ions. Many such foreign (impurity) multiply-charged ion species are found in plasma discharges, as a result of gas recycling and damage to the surrounding surfaces by energetic plasma particles. Typical low-Z ions are carbon and oxygen; the major constituents of … more

Date: January 1, 1981

Creator: Hogan, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron-impact ionization: time-dependent and other numerical approaches

Algorithms for the solution of electron-atom and electron-ion ionization collisions are described. Some results are given on the ionization of ground and excited states and ionized targets. (WHK)

Date: January 1, 1982

Creator: Bottcher, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electrical Resistivity of Strongly Coupled Plasmas in Intense Fields

It is now possible to measure the electrical resistivity, or alternatively the electron collision frequency, in strongly coupled plasmas through the use of very fast laser pulses. In such experiments, the effect of the intense laser field needs to be included in the calculation of material transport coefficients. We derive a form for the electrical resistivity which includes the effects of strong correlations, as well as an external electric field. Our results are compared with other theories a… more

Date: August 1, 1989

Creator: Cauble, R.; Rogers, F.J. (Lawrence Livermore National Lab., CA (USA)) & Rozmus, Wojtek (Alberta Univ., Edmonton, AB (Canada). Theoretical Physics Inst.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Proposed LLNL electron beam ion trap

The interaction of energetic electrons with highly charged ions is of great importance to several research fields such as astrophysics, laser fusion and magnetic fusion. In spite of this importance there are almost no measurements of electron interaction cross sections for ions more than a few times ionized. To address this problem an electron beam ion trap (EBIT) is being developed at LLNL. The device is essentially an EBIS except that it is not intended as a source of extracted ions. Instead … more

Date: July 2, 1985

Creator: Marrs, R.E.; Egan, P.O.; Proctor, I.; Levine, M.A.; Hansen, L.; Kajiyama, Y. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Application of ECR ion source beams in atomic physics

The availability of intense, high charge state ion beams from ECR ion sources has had significant impact not only on the upgrading of cyclotron and synchrotron facilities, but also on multicharged ion collision research, as evidenced by the increasing number of ECR source facilities used at least on a part time basis for atomic physics research. In this paper one such facility, located at the ORNL ECR source, and dedicated full time to the study of multicharged ion collisions, is described. Exa… more

Date: January 1, 1987

Creator: Meyer, F.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurements of ionization balance parameters in atomic ions

This report discusses the measurement of the dielectronic recombination rate of carbon 3 plus ions. (LSP).

Date: June 1, 1991

Creator: Kohl, J. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron impact ionization of heavy ions: some surprises

This paper reports the results of calculations of electron impact ionization cross sections for a variety of heavy ions using a distorted wave Born-exchange approximation. The target is described by a Hartree-Fock wavefunction. The scattering matrix element is represented by a triple partial wave expansion over incident, scattered, and ejected (originally bound) continuum states. These partial waves are computed in the potentials associated with the initial target (incident and scattered waves)… more

Date: August 22, 1986

Creator: Younger, S.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Role of indirect processes in electron-impact ionization of multicharged ions

Recent studies of electron impact ionization in this laboratory are discussed with emphasis on the role of indirect processes. Examples are used to illustrate the importance of excitation-autoionization (Ti/sup 2 +/ and Al/sup 2 +/), autoionizing metastable ions in the Na isoelectronic sequence, multiple ionization (triple ionization of Xe/sup 6 +/), the relative importance of indirect ionization with increasing charge in the Mg isoelectronic sequence, and the extension of ionization measuremen… more

Date: January 1, 1985

Creator: Gregory, D.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental atomic physics in heavy-ion storage rings

This paper outlines the discussion which took place at the ''round table'' on experimental atomic physics in heavy-ion storage rings. Areas of discussion are: electron-ion interactions, ion-ion collisions, precision spectroscopy of highly charged ions, beta decay into bound final states, and atomic binding energies from spectroscopy of conversion elections. 18 refs., 1 tab. (LSP)

Date: January 1, 1987

Creator: Datz, S.; Andersen, L.H.; Briand, J.P. & Liesen, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Stieltjes-moment-theory technique for calculating resonance width's

A recently developed method for calculating the widths of atomic and molecular resonances is reviewed. The method is based on the golden-rule definition of the resonance width, GAMMA(E). The method uses only square-integrable, L/sup 2/, basis functions to describe both the resonant and the non-resonant parts of the scattering wave function. It employs Stieltjes-moment-theory techniques to extract a continuous approximation for the width discrete representation of the background continuum. Its i… more

Date: December 1, 1978

Creator: Hazi, A.U.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron collisional excitation of K- and B-like ions

No Description Available.

Date: June 30, 1990

Creator: Msezane, A.Z.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Fusion Energy Division annual progress report period ending December 31, 1983

The Fusion Program carries out work in a number of areas: (1) experimental and theoretical research on two magnetic confinement concepts - the ELMO Bumpy Torus (EBT) and the tokamak, (2) theoretical and engineering studies on a third concept - the stellarator, (3) engineering and physics of present-generation fusion devices, (4) development and testing of diagnostic tools and techniques, (5) development and testing of materials for fusion devices, (6) development and testing of the essential te… more

Date: September 1, 1984

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron-impact excitation of multiply-charged ions using energy loss in merged beams: e + Si sup 3 + (3s sup 2 S sub 1/2 ) yields e + Si sup 3 + (3p sup 2 P sub 1/2, 3/2 )

For the first time absolute total cross sections for electron-impact excitation of a multiply-charged ion have been measured using an electron-energy-loss technique. Measurements were made near threshold for the process e + Si{sup 3+}(3s{sup 2}S{sub 1/2}) {yields} e + Si{sup 3+}(3p{sup 2}P{sub 1/2},{sub 3/2}) -- 8.88 eV. The 10{sup {minus}15} cm{sup 2} measured cross section agrees with results of 7-state close coupling calculations to better than the {plus minus}20% (90% CL) total uncertainty … more

Date: January 1, 1990

Creator: Wahlin, E.K.; Thompson, J.S.; Dunn, G.H. (National Inst. of Standards and Technology, Boulder, CO (USA) Joint Inst. for Lab. Astrophysics, Boulder, CO (USA)); Phaneuf, R.A.; Gregory, D.C. (Oak Ridge National Lab., TN (USA)) & Smith, A.C.H. (Oak Ridge National Lab., TN (USA) University Coll., London (UK))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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On the utility and ubiquity of atomic collision physics

This paper is divided into three parts. In the introduction, we discuss the history and makeup of ICPEAC. In the second part, we discuss the extent of applicability of atomic collision physics. In the third part, we chose one subject (dielectronic excitation) to show the interrelationship of various sub-branches of atomic collision physics. 28 refs., 14 figs.

Date: January 1, 1989

Creator: Datz, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Theory of recombination processes

The theory is devoted to the following three processes: (1) radiative recombination, (2) dissociative recombination, and (3) three-body recombination. (MOW)

Date: January 1, 1979

Creator: Bottcher, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Low-energy collisions of multiply charged ions with electrons, atoms and surfaces

Results are presented from recent experiments at the ORNL-ECR Multicharged Ion Research Facility which have addressed low-energy interactions of multiply charged ions with electrons, hydrogen atoms and metal surfaces. The specific processes for which results are reported are electron-impact excitation, electron capture and ion neutralization. The objective of these studies is a more detailed understanding of the mechanisms which govern the interactions of multicharged ions at low (or near-thres… more

Date: January 1, 1991

Creator: Phaneuf, R. A.; Meyer, F. W.; Gregory, D. C.; Havener, C. C.; Zeijlmans van Emmichoven, P. A.; Overbury, S. H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron-ion interaction cross sections determined by x-ray spectroscopy on EBIT

The Livermore electron beam ion trap (EBIT) is used to measure electron-ion interactions with high-resolution x-ray spectroscopy. Measurements are presented of the K{alpha} x-ray emission of heliumlike Fe{sup 24+} that demonstrate the effect of various processes on the spectrum of highly charged heliumlike ions. In particular, we have studied how dielectronic recombination into high-n Rydberg levels and resonance excitation processes contribute to the x-ray emission near threshold for direct el… more

Date: June 26, 1991

Creator: Beiersdorfer, P.; Cauble, R.; Chantrenne, S.; Chen, M.; Knapp, D.; Marrs, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Introductory remarks on electron capture by multicharged ions

An overview is presented of applications of multicharged-ion electron capture and, through the qualitative assessment of availability of information, the general status of current understanding of such capture. A chart is given on which the various ion collision processes are related to other pertinent fields of physical research notably fusion, astrophysics, the solar corona, and lasers. The production and transport of ions is also noted. The symposium considers collision velocities less than … more

Date: January 1, 1979

Creator: Crandall, D.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Survey of atomic processes in edge plasmas

A review of the most important reactions of atomic and molecular hydrogen with the fusion edge plasma electrons and ions is presented. An appropriate characterization of the considered collision processes, useful in plasma edge studies (evaluated cross sections, reaction rates, energy gain/loss per collision, etc.) has been performed. While a complete survey of atomic physics of fusion edge plasmas will be given elsewhere shortly, we demonstrate here the relevance of the atomic collision proces… more

Date: November 1, 1983

Creator: Janev, R. K.; Post, D. E.; Langer, W. D.; Evans, K.; Heifetz, D. B. & Weisheit, J. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department