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in subjects: "Charge Exchange"

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Numerical calculation of impurity charge state distributions

The numerical calculation of impurity charge state distributions using the computer program IMPDYN is discussed. The time-dependent corona atomic physics model used in the calculations is reviewed, and general and specific treatments of electron impact ionization and recombination are referenced. The complete program and two examples relating to tokamak plasmas are given on a microfiche so that a user may verify that his version of the program is working properly. In the discussion of the examp… more

Date: September 1, 1977

Creator: Crume, E. C. & Arnurius, D. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Neutral beamline with improved ion-energy recovery

A neutral beamline employing direct energy recovery of unneutralized residual ions is provided which enhances the energy recovery of the full energy ion component of the beam exiting the neutralizer cell, and thus improves the overall neutral beamline efficiency. The unneutralized full energy ions exiting the neutralizer are deflected from the beam path and the electrons in the cell are blocked by a magnetic field applied transverse to the beam direction in the neutralizer exit region. The ions… more

Date: April 13, 1981

Creator: Kim, J.

Item Type: Patent

Partner: UNT Libraries Government Documents Department

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Measurements of energetic helium-3 minority distributions during ion cyclotron radio-frequency heating in the Princeton Large Torus

Ion cyclotron radio-frequency heating experiments were performed with a /sup 3/He minority ion species in a /sup 4/He majority plasma in the Princeton Large Torus. The energetic /sup 3/He ion ''tail'' was measured directly with a charge exchange neutral analyzer for the first time. Comparisons with bounce-averaged quasi-linear calculations suggest a modestly peaked radi-frequency power deposition profile. The double charge exchange process /sup 3/He/sup + +/ )plus) /sup 4/He/sup 0/ )plus) /sup … more

Date: March 1, 1988

Creator: Hammett, G. W.; Kaita, R. & Wilson, J. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Theoretical studies of highly ionized species. Progress report, March 1, 1977--February 28, 1978

The relativistic random phase approximation has been used to study the helium, beryllium, magnesium and zinc isoelectronic sequences. Model potential methods have been employed to study multi-photon ionization of sodium from the ground and excited states. Forbidden decays in the Be and Mg isoelectronic sequences have been investigated. The 1s2p/sup 2/ /sup 2/P and 1s2p/sup 2/ /sup 2/D states of lithium-like ions have been studied. Calculations of radiative charge transfer have been carried out.

Date: November 1, 1977

Creator: Dalgarno, A. & Victor, G.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Charge exchange photoproduction and the a sub 1 (1260)

Although recent analyses of {tau}-lepton decay and a reanalysis of hadron production data gave consistent results for the mass of the a{sub 1}({approximately}1250 MeV), other results, both experimental and theoretical, have suggested a significantly smaller value for this parameter. The purpose of this talk is to present our data on the charge-exchange photoproduction reaction, {gamma}{rho} {yields} {Delta}{sup ++}{pi}{sup +}{pi}{sup {minus}}{pi}{sup {minus}}. Our data derive from a hydrogen bu… more

Date: January 1, 1991

Creator: Condo, G. T.; Handler, T. & Blackett, G. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Benchmarks of neutral beam injection codes for stellarators

The 3-dimensional geometry of stellarators/heliotrons make it more difficult to calculate beam deposition and thermalization. Extensive comparisons between the Oak Ridge and Kyoto codes were undertaken, using a simplified model for the Heliotron-E plasma and magnetic field. The perpendicular injection geometry causes most of the energetic fast ions to be helically trapped. The high transform and shear of the heliotron configuration helps to confine these orbits, but energy losses in the model c… more

Date: January 1, 1987

Creator: Fowler, R.H.; Rome, J.A.; Morris, R.N. & Hanatani, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pion induced double-charge exchange above the resonance

The zero degree excitation function for ({pi}{sup +}, {pi}{sup -}) is calculated for pion energies of 300 to 1400 MeV assuming a sequential mechanism. The cross section around 1225 MeV is 10{sup 4} smaller than at 800 MeV. Experiments at this energy should be ideal for searches for effects due to exchange currents, and other non-conventional mechanisms. 15 refs.

Date: October 24, 1989

Creator: Oset, E.; Strottman, D. (Valencia Univ. (Spain). Dept. de Fisica Teorica & Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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BNL Neutral-Beam Development Group. Progress report FY 1981

The Brookhaven High Energy Neutral Beam Development Group is developing injector systems, particularly for the next generation of fusion mirror and tokamak experiments. These injectors are based on the acceleration and neutralization of negative deuterium ions, to utilize their high neutralization efficiency which is nearly independent of energy above 50 keV/nucleon.

Date: January 15, 1982

Creator: Prelec, K. & Sluyters, T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Picosecond infrared study of intramolecular energy transfer in ((phen)(CO) sub 3 Re sup I (NC)Ru sup II (CN)(bpy) sub 2 ) sup +

The dynamics and mechanism of intramolecular energy transfer in ((phen)(CO){sub 3}Re{sup I}(NC)Ru{sup II}(CN)(bpy){sub 2})+ following metal-to-ligand charge transfer excitation have been studied using picosecond infrared spectroscopy.

Date: January 1, 1992

Creator: Dyer, R. B.; Peterson, K. A.; Gordon, K. C.; Woodruff, W. H. (Los Alamos National Lab., NM (United States)); Schoonover, J. R.; Meyer, T. J. (North Carolina Univ., Chapel Hill, NC (United States). Dept. of Chemistry) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Total scattering cross sections and interatomic potentials for neutral hydrogen and helium on some noble gases

Measurements of energy-dependent scattering cross sections for 30 to 1800 eV D incident on He, Ne, Ar, and Kr, and for 40 to 850 eV He incident on He, Ar, and Kr are presented. They are determined by using the charge-exchange efflux from the Princeton Large Torus tokamak as a source of D or He. These neutrals are passed through a gas-filled scattering cell and detected by a time-of-flight spectrometer. The cross section for scattering greater than the effective angle of the apparatus (approx. =… more

Date: April 1, 1985

Creator: Ruzic, D.N. & Cohen, S.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Charge exchange recombination spectroscopy measurements in the extreme ultraviolet region of central carbon concentrations during high power neutral beam heating in TFTR (Tokamak Fusion Test Reactor)

The carbon concentration in the central region of TFTR discharges with high power neutral beam heating has been measured by charge-extracted recombination spectroscopy (CXRS) of the C{sup +5} n = 3--4 transition in the extreme ultraviolet region. The carbon concentrations were deduced from absolute measurements of the line brightness using a calculation of the beam attenuation and the appropriate cascade-corrected line excitation rates. As a result of the high ion temperatures in most of the di… more

Date: September 1, 1989

Creator: Stratton, B. C.; Fonck, R. J.; Ramsey, A. T.; Synakowski, E. J.; Grek, B.; Hill, K. W. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Efficient ionizer for polarized H/sup -/ formation

An ionizer is under development for a polarized H/sup -/ source based on the resonant charge exchange reaction polarized H/sup 0/ + D/sup -/ ..-->.. polarized H/sup -/ + D/sup 0/. The polarized H/sup 0/ beam passes through the center of a magnetron surface-plasma source having an annular geometry, where it crosses a high current (approx.0.5 A), 200 eV D/sup -/ beam. Calculations predict an H/sup 0/ ..-->.. H/sup -/ ionization efficiency of approx.7%, more than an order of magnitude higher than … more

Date: January 1, 1985

Creator: Alessi, J.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron-spin-polarized targets for a collisionally-pumped polarized-ion source

Collisional pumping has been proposed as a mechanism for producing polarized ion beams more intense by orders of magnitude than those from the best existing sources. One implementation of this method employs a very thick electron-spin-polarized alkali-vapor target in a low magnetic field, and is characterized by a predicted 100% spin-transfer efficiency from the target to the beam. Target characteristics and design constraints are discussed.

Date: May 1, 1985

Creator: Kaplan, S. N.; Burrell, C. F.; Pyle, R. V.; Ruby, L.; Schlachter, A. S. & Stearns, J. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Methods for independent plasma production and beam injection for H/sup +/. -->. H/sup -/ surface conversion

Based on the Oak Ridge National Laboratory (ORNL) source development program, ways to create a uniform and dense plasma are briefly reviewed. The positive ions so created will be accelerated towards a surface convertor for producing negative ions. The convertor will be used for reducing the electrons in the extraction region. The significant results and features of this study are presented.

Date: January 1, 1977

Creator: Tsai, C C; Stirling, W L & Davis, R C

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fast time resolution charge-exchange measurements during the fishbone instability in the poloidal divertor experiment

Measurements of fast ion losses due to the fishbone instability during high ..beta../sub T/q neutral beam heated discharges in the Poloidal Divertor Experiment have been made using two new vertical-viewing charge-exchange analyzers. The measurements show that the instability has an n=1 toroidal mode number, and that it ejects beam ions in a toroidally rotating beacon directed outward along a major radius. Observations of ejected ions with energies up to twice the beam injection energy at R appr… more

Date: January 1, 1984

Creator: Beiersdorfer, P.; Kaita, R. & Goldston, R.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Formation of H/sup -/ by charge transfer in alkaline-earth vapors

Progress on the study of H/sup -/ formation by charge transfer in alkaline-earth vapors is reported. The H/sup -/ equilibrium yield in strontium vapor reaches a maximum of 50% at an energy of 250 eV/amu, which is the highest H/sup -/ yield reported to date.

Date: October 1, 1983

Creator: Schlachter, A.S. & Morgan, T.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Plasma production and flow in negative ion beams

Plasma generated in low-density vapor by a negative ion beam has been studied experimentally and computationally. We show that space charge neutralization of the beam occurs at very low vapor density, and that correspondingly the electron density may be much less than the beam and plasma ion densities. When there is a large local gas density, as in a charge changing cell, the resulting high electron density is also localized to the same region. Therefore, very few electrons will reach a negativ… more

Date: September 21, 1977

Creator: Anderson, O. A. & Hooper, E. B. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Formation of negative ions by charge transfer: He/sup -/ to Cl/sup -/

Formation of energetic beams of negative ions of elements with atomic numbers 2 to 17 (helium to chlorine) by charge transfer in metal vapors is discussed.

Date: December 1, 1983

Creator: Schlachter, A.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Neutralization efficiency of plasma targets for high energy negative ions

Plasma targets generated by hollow cathode discharges are used to neutralize a variety of multi-MeV negative ions as heavy as 28 a.m.u. Our plan is to determine the neutralization efficiency of hydrogen and argon plasma targets for D/sup -/, Li/sup -/, C/sup -/, O/sup -/, and Si/sup -/ at beam energiens of 2 to 8 MeV. The experiment is still in progress. Encouraging initial results are reported. 3 references, 4 figures, 1 table.

Date: January 1, 1983

Creator: Hershcovitch, A. I.; Johnson, B. M.; Kovarik, V. J.; Meron, M.; Jones, K. W. & Prelec, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Numerical model for radial transport in the ELMO Bumpy Torus

Neutral and charged particle densities and temperatures are calculated as functions of radius for the toroidal plasma in the ELMO Bumpy Torus (EBT) experiment. Energy dependent ionization and charge-exchange rates, ambipolar diffusion, and self-consistent radial electric field profiles are included. Variation in magnetic field due to finite plasma pressure, effects of energetic electron rings, and transport due to drift waves and magnetic field errors are neglected. Diffusion is assumed to be n… more

Date: November 1, 1977

Creator: Jaeger, E. F. & Hedrick, C. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The sup 11 Li neutron halo radius from pion double charge exchange

We have analzed the pion double charge exchange data for the direct population of the ground state of {sup 11}Li by the {sup 11}B({pi}{sup {minus}}, {pi}{sup +}){sup 11}Li reaction and find that the measured cross section determines the rms radius of the last two neutrons in {sup 11}Li to be 5.1{sub {minus} 0.8}{sup +0.6} fm. It is shown that the pion cross-section falls off as the sixth power of the assumed neutron halo radius, so that a radius greater than about 6 fm is ruled out. Indeed, pio… more

Date: January 1, 1991

Creator: Hayes, A.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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ATSU Point Design (gasdynamics)

In this presentation the basic principles outlined in the first talk ''Gas Cell Neutralizers'' will be applied to a problem of particular interest viz., the design of a ''gasdynamic free-jet'' neutralizer for the Los Alamos ATSU project. What will be presented here does not in any way represent the final gas neutralizer design for ATSU. Rather, the material presented herein should be viewed as simply a preliminary design intended to identify and gain insight into the more subtle issues that mus… more

Date: June 1, 1985

Creator: Fuehrer, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electronic transitions of some pi-molecular charge transfer complexes. [Anthracene--pyromellitic dianhydride (PMDA) or pyrene--PMDA in naphthalene--PMDA host]

A unique phonon progression in the phosphorescence spectrum of pyrene-PMDA (Py-PMDA) in naphthalene-PMDA (N-PMDA) is reported. Calculations of the electron-phonon coupling strength parameter for the ground and excited states indicate strong coupling for the fractional CT contribution of Py-PMDA to the observed phosphorescent state. Model calculations indicate that the observed low frequency phonon mode corresponds to a low energy rotation of the rigid guest complex and not a symmetric donor-acc… more

Date: December 1, 1977

Creator: Beckman, R. L.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Neutralization of a fast negative-ion beam

Neutralization of a fast negative-ion beam, primarily H/sup -/, is discussed in terms of competing one- and two-electron detachment processes in a variety of media: gas (vapor), plasma, liquid sheet, solid foil.

Date: January 1, 1986

Creator: Schlachter, A. S.; Mowat, J. R.; Stearns, J. W.; Gohil, P. & Pyle, R. V.

Item Type: Article

Partner: UNT Libraries Government Documents Department