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in subjects: "Recombination"

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Direct spectroscopic observation of charge-exchange recombination of medium-Z elements in the PLT tokamak

We report the first observation of line emission resulting directly from charge-exchange recombination of medium-Z elements (Al, Sc) injected into a PLT discharge. Transitions due to the radiative cascade immediately following charge-exchange of He-like Al and Sc were observed by a VUV spectrograph and two air monochromators. In two cases, AlXI 3209 A and ScXIX 112.1 A, the observed transition had not previously been experimentally identified. Spatial scans provided information on the profile o… more

Date: March 1, 1984

Creator: Skinner, C. H.; Suckewer, S.; Cohen, S. A.; Schilling, G.; Wilson, R. & Stratton, B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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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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Generation of H sup minus , H sub 2 (v double prime ), and H atoms by H sub 2 sup + and H sub 3 sup + ions incident upon barium surfaces

The generation of vibrationally excited molecules by electron excitation collisions and the subsequent generation of negative ions by dissociative attachment to these molecules has become a standard model for volume source operation. These processes have been supplemented recently by the demonstration of atom-surface recombination to form vibrationally excited molecules, and enhanced negative ion formation by protons incident upon barium electrodes. In this paper we consider the additional proc… more

Date: January 1, 1989

Creator: Hiskes, J.R. & Karo, A.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Dielectronic recombination measurements of highly-charged heliumlike and neonlike ions using an electron beam ion trap

The electron beam ion trap (EBIT) at LLNL is a unique device designed to measure the interactions of electrons with highly-charged ions. We describe three methods used at EBIT to directly measure the dielectronic recombination (DR) process: the intensity of the stabilizing x-rays is measured as a function of electron beam energy; the ions remaining in a particular ionization state are counted after the electron beam has been held at a fixed electron energy for a fixed time; and high-resolution … more

Date: January 1, 1991

Creator: Schneider, M. B.; Knapp, D. A.; Beiersdorfer, P.; Chen, M. H.; Scofield, J. H.; Bennett, C. L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Activated recombinative desorption: a potential component in mechanisms of spacecraft glow

The concept of activated recombination of atomic species on surfaces is capable of explaining the production of vibrationally and translationally excited desorbed molecular species. Equilibrium statistical mechanics predicts that the molecular quantum state distributions of desorbing molecules is a function of only the surface temperature when the adsorption probability is unity and independent of initial collision conditions. In most cases though the adsorption probability is dependent upon in… more

Date: January 1, 1985

Creator: Cross, J.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Silicon on ceramic process. Silicon sheet growth for Large-Area Silicon Sheet Task of the Low-Cost Solar Array Project. Annual report No. 4, September 29, 1978-September 30, 1979

The objective of this research program is to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. The effort is divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating; (3) material characterization; (4) cell fabricati… more

Date: October 31, 1979

Creator: Chapman, P W; Zook, J D; Heaps, J D; Koepke, B; Grung, B L & Schuldt, S B

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Role of valons in low-p/sub T/ physics

Hadron structure is described in the framework in which a nucleon is treated as a composite system of three valence quark clusters, called valons. Their momentum distribution is extracted from deep inelastic scattering data. The valon representation provides a quantitative description of the recombination function, which characterizes the hadronization of quarks. A formalism is then developed in terms of valons and quarks such that the inclusive distributions for hadronic reactions at low-p/sub… more

Date: January 1, 1980

Creator: Hwa, R.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Photovoltaic mechanisms in polycrystalline thin-film silicon solar cells

Fundamental limitations on the performance of Si solar cells are shown to be quite different from those that have been conventionally invoked. Particularly for heavy-doping effects, the usual models are shown to be invalid and a new method is devised for calculating the reverse saturation current of a heavily doped device in which nearly all minority carriers reach the junction (viz., good blue-response). Calculations by the new method show: (1) increased doping above 10/sup 18/cm/sup -3/ does … more

Date: February 1, 1980

Creator: Redfield, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Dissociative recombination of interstellar ions: electronic structure calculations for HCO/sup +/

The present study of the interstellar formyl ion HCO/sup +/ is the first attempt to investigate dissociative recombination for a triatomic molecular ion using an entirely theoretical approach. We describe a number of fairly extensive electronic structure calculations that were performed to determine the reaction mechanism of the e-HCO/sup +/ process. Similar calculations for the isoelectronic ions HOC/sup +/ and HN/sub 2//sup +/ are in progress. 60 refs.

Date: July 2, 1985

Creator: Kraemer, W.P. & Hazi, A.U.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Towards a quantitative approach to the utilization of magnetic effects as a means of isotopic enrichment

The photolysis of methyldesoxybenzoin in sodium dodecyl sulfate micellar solutions, produces benzaldehyde and styrene as disproportionation products of the triplet geminate radical pair. We have found that both the benzaldehyde and the recovered methyldeoxybenzoin are enriched in 13-C. These results provide the first direct evidence that both recombination and disproportionation are identically selective to the magnetic isotope effect, an important point anticipated by theory, but previously un… more

Date: May 1, 1992

Creator: Turro, N.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Amorphous thin films for solar-cell applications. Final report, September 11, 1978-September 10, 1979

In Section II, Theoretical Modeling, theories for the capture of electrons by deep centers in hydrogenated amorphous silicon (a-Si:H) and for field-dependent quantum efficiency in a-Si:H are presented. In Section III, Deposition and Doping Studies, the optimization of phosphorus-doped a-Si:H carried out in four different discharge systems is described. Some details of the dc proximity and rf magnetron discharge systems are also provided. Preliminary mass spectroscopy studies of the rf magnetron… more

Date: February 1, 1980

Creator: Carlson, D. E.; Balberg, I.; Crandall, R. S.; Goldstein, B. C.; Hanak, J. J.; Pankove, J. I. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A five-picosecond electron pulse from ANL (Argonne National Laboratory) L-Band Linac

The pulse-compression system of the Argonne National Laboratory Chemistry Division L-Band Linac, presented at the 1986 Linear Accelerator Conference at Stanford, California, has been completed. A five-picosecond-wide electron pulse containing 6 {times} 10{sup {minus}9} coulomb charge has been achieved. Acceleration parameters and the pulse-width measurement technique are discussed, and future plans for the utilization of this pulse in radiation chemistry studies are presented. 5 refs., 4 figs.

Date: January 1, 1989

Creator: Cox, G. L.; Jonah, C. D.; Ficht, D. T.; Mavrogenes, G. S. & Sauer, M. C. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fundamental studies of grain boundary passivation in polycrystalline silicon with application to improved photovoltaic devices. A final research report covering work completed from February-December 1979

Several aspects of the electrical properties of silicon grain boundaries have been studied. The temperature dependence of the zero-bias conductance and capacitance of single boundaries has been measured and shown to be in good agreement with a simple double depletion layer/thermal emission (DDL/TE) model developed to predict the transport properties of such structures. In addition, it has been shown that deconvolution of the I-V properties of some boundaries via a deconvolution scheme suggested… more

Date: February 1, 1980

Creator: Seager, C. H. & Ginley, D. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurements of the hydrogenic recombination coefficient for the TFTR vacuum vessel

Characteristic values of the recombination rate coefficient for hydrogen and deuterium in stainless steel have been measured for the inner wall of the TFTR vacuum vessel for vessel temperatures of 25 to 100 C. In situ measurements of k/sub r/ are important for predicting the hydrogen isotope retention in the wall as a function of time, temperature, and discharge exposure, particularly because existing laboratory measurements of k/sub r/ for stainless steel span a range of four orders of magnitu… more

Date: December 1, 1983

Creator: Dylla, H. F.; Cecchi, J. L. & Knize, R. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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He/sup + +/ transport in the PDX tokamak

A powerful new approach to the study of particle transport and helium ash confinement in high-temperature fusion plasmas is demonstrated by charge-exchange recombination spectroscopy of He/sup + +/ in ohmically heated PDX discharges. Time and space resolved measurements of He/sup + +/ density following a short puff of helium gas into the plasma edge are fitted using a diffusive/convective transport model with coefficients D = (2.1 +- 0.9) x 10/sup 4/ cm/sup 2/ s/sup -1/ and v(r)/D = (0.8 +- 0.3… more

Date: December 1, 1983

Creator: Fonck, R.J. & Hulse, R.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Advanced amorphous materials for photovoltaic conversion. Annual report, October 1, 1978-September 30, 1979

The objectives of this project are twofold: (1) to investigate new amorphous semiconductor (a-SC) materials, in which recombination centers are passivated, using plasma deposition techniques; and (2) to characterize the optoelectronic properties pertaining to both majority-carrier and minority-carrier transport in as-deposited films and in devices. The electronic properties of plasma-deposited a-Si:H alloys were studied as functions of oxygen and nitrogen impurities. Over a wide range of proces… more

Date: January 1, 1980

Creator: Griffith, R. W.; Kampas, F. J.; Vanier, P. E. & Hirsch, M. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Characterization of Open-Cycle Coal-Fired MHD Generators. Quarterly Technical Summary Report No. 3, January 1--March 31, 1977. [Negative Ion Formation, Electron/Slag Interaction, and Alkali/Slag Interaction]

The purpose of this contract effort is to understand how nonfuel components of coal will affect the electron and alkali seed chemistry in a high temperature coal combustion system like that envisioned for direct fired MHD generators. Three specific problems are being considered during this contract period. The first problem area is to characterize the formation of negative ions due to electron attachment processes in the combustion flow. While some stable negative ions may be formed from hydroc… more

Date: April 15, 1977

Creator: Kolb, C. E.; Yousefian, V.; Wormhoudt, J.; Martinez-Sanchez, M. & Kerrebrock, J. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Free ion yields in liquids: Molecular structure and track effects

The signal generated in a liquid-filled ionization chamber is proporational to the ions that escape, the free ion yield or, G{sub fi}. Recent results show how molecular structure, rate of energy loss (dE/dx) and pressure affect G{sub fi} and give further insight into the ionization process in liquids. As a consequence of the passage of high energy charged particles through a liquid, molecules are ionized and excited. The electrons have kinetic energy initially which allow them to travel some di… more

Date: January 1, 1992

Creator: Holroyd, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Tenth Atomic Physics Program workshop

This report contains short papers and abstracts on the following main topics: Ion-atom collision theory; laser physics; spectroscopy of atoms; spectroscopy of ions; and high velocity collisions.

Date: October 1, 1989

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Photoionization and photorecombination cross sections of non-hydrogenic states in plasmas

We use Hartree-Slater self-consistent-field wave functions to compute photoionization and photorecombination cross sections and rates for partially ionized iron atoms, both in their isolated state and in a plasma environnment. The calculated cross sections are fitted to analytic expressions so that the photoionization and recombination rates can be given in closed forms. Our analytic representation satisfy the requirement that the oscillator-strength sums S/sub 0/, S/sub 1/, and S/sub 2/ must c… more

Date: September 1, 1986

Creator: Rozsnyai, B. F. & Jacobs, V. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A model for electron/ion recombination in ionization chambers

The recombination of free electrons and positive ions along charged particle tracks in gases has been modeled using electron tranport equations, which assume homogeneous distribution in the vicinity of the tracks. The equations include space charge terms, which have been negelected in previous models. A formula for the electron yield as a function of detector applied potential is obtained from a perturbation solution valid when the ratio of the Debye length to the charge column radius is larger… more

Date: May 1, 1988

Creator: Sailor, W. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Gas recombination device design and cost study. Final report

Under a contract with Argonne National Laboratory, VARTA Batterie AG. conducted a design and cost study of hydrogen-oxygen recombination devices (HORD) for use with utility load-leveling lead-acid cells. Design specifications for the devices, through extensive calculation of the heat-flow conditions of the unit, were developed. Catalyst and condenser surface areas were specified. The exact dimensions can, however, be adjusted to the cell dimension and the space available above the cell. Design … more

Date: July 1, 1980

Item Type: Report

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

open access

Proceedings of the workshop on the modification of the upper atmosphere by Satellite Power System (SPS) propulsion effluents

Results of a workshop held in June 1979, to identify research needs for evaluating environmental impacts on the upper atmosphere (here defined as greater than 70 km) due to Satellite Power System (SPS) transport, i.e., propulsion and reentry are presented. The substantial injections of water and hydrogen therefrom may lead to global-scale regions of reduced ionization in the ionospheric F-Region that may have a serious impact on worldwide HF radio communications; and the resulting possibly sign… more

Date: June 1, 1980

Creator: Bauer, E.

Item Type: Article

Partner: UNT Libraries Government Documents Department