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Stability of space-charge neutralized beams

Description: Consideration is given to the stability of negative ion beams which are neutralized through ionization of a background gas. Two types of instabilities are examined. First, beam-plasma instabilities are analyzed with the dispersion relation showing that they are unimportant if the beam velocity is less than the electron thermal velocity. Second, results of a computer simulation on the flow of a cylindrical beam and the resulting background plasma show that when the background neutral gas density… more
Date: September 22, 1977
Creator: Turnbull, R. J. & Hooper, E. B. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Numerical calculation of impurity charge state distributions

Description: 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: Refine your search to only 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)

Description: 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: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Plasma production and flow in negative ion beams

Description: 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: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Solution of the Fokker-Planck equation with mixing of angular harmonics by beam-beam charge exchange

Description: A method for solving the linear Fokker-Planck equation with anisotropic beam-beam charge exchange loss is presented. The 2-D equation is transformed to a system of coupled 1-D equations which are solved iteratively as independent equations. Although isotropic approximations to the beam-beam losses lead to inaccurate fast ion distributions, typically only a few angular harmonics are needed to include accurately the effect of the beam-beam charge exchange loss on the usual integrals of the fast i… more
Date: September 1, 1989
Creator: Mikkelsen, D.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Progress Report for C-Mod Collaboration

Description: The aims of the collaboration have not changed. The report describes progress in the areas of FRCECE system, charge exchange recombination spectroscopy, Beam-Emission spectroscopy (BES), as well as other contributions. A significant number of resulting publications are listed.
Date: September 30, 2008
Creator: Gentle, Kenneth W.; Rowan, William & Phillips, Perry
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Calculation of the Thermal Footprint of Resonant Magnetic Perturbations in DIII-D

Description: The effect of resonant magnetic perturbations on heat transport in DIII-D H-mode plasmas has been calculated by combining the TRIP3D field-line tracing code with the E3D two-fluid transport code. Simulations show that the divertor heat flux distribution becomes non-axisymmetric because heat flux is efficiently guided to the divertor along the three-dimensional invariant manifolds of the magnetic field. Calculations demonstrate that heat flux is spread over a wider area of the divertor target, t… more
Date: September 14, 2007
Creator: Joseph, I; Evans, T; Moyer, R; Fenstermacher, M; Groth, M; Kasilov, S et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Progress at LAMPF

Description: This report discusses project experiments done at Lampf under the following topics: nuclear and particle physics; astrophysics; atomic and molecular physics; materials science; nuclear chemistry; radiation effects; radioisotope production; and theory.
Date: September 1, 1989
Creator: Poelakker, K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of the mass and energy resolution of the E parallel B charge exchange analyzer for TFTR

Description: The charge exchange diagnostic for TFTR requires simultaneous multispecie (H/sup +/, D/sup +/, ..gamma../sup +/) analysis of particles in the energy range of 0.5 - 150 keV. The analyzer design chosen to provide this capability employs a wide gap semi-circular region of superimposed parallel electric and magnetic fields to accomplish mass and energy resolution, respectively. Combined with a large area, multi-anode microchannel plate detector, this arrangement will enable the energy distributions… more
Date: September 1, 1979
Creator: Kaita, R. & Medley, S. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Charge exchange in low energy D and T beams. [100 and 150 keV]

Description: The process of charge exchange of deuterons and tritons in a hydrogenic gas target is examined and the charge fraction versus target thickness is calculated and plotted. The approach to equilibrium of the charge exchange interaction is examined at various energies. Finally, the possible effects on a low energy fusion cross section experiment are briefly looked at. 5 references.
Date: September 1, 1979
Creator: King, S.E. & Jarmie, N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Charge state evolution in an ion trap irradiated by VUV synchrotron radiation

Description: The energies of photons obtainable from the VUV ring at the National Synchrotron Light Source (NSLS) are ideally suited for high-efficiency ionization of atomic outer-shell electrons. Given the high fluxes of photons available on a wiggler beam line, multiple photoionization in an ion trap can be easily achieved within times short compared to typical ion storage times in the trap. Measurements of the time evolution of ion populations in such a trap can yield ionic photoionization cross sections… more
Date: September 1, 1987
Creator: Meron, M.; Johnson, B. M.; Jones, K. W. & Church, D. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Negative deuterium ions for tandem mirror next step and tandem mirror reactors

Description: Recent designs for mirror fusion reactors with good power balance include ambipolar potential plugs to reduce end losses and thermal barriers to maintain a difference in electron temperature between the large-volume central cell plasma and the confining end plugs. These designs led to several new requirements for D/sup 0/ neutral beams derived from negative ions at energies of 150 to 200 keV and possibly higher. Such beams are required for injection of fat ions into the plugs and the barrier an… more
Date: September 25, 1980
Creator: Hamilton, G.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Transport of neutral atoms and molecules in TFCX

Description: The distribution of neutrals in the proposed reactor TFCX has been modeled by the 3-D Monte Carlo neutral transport code DEGAS, which has been run in conjunction with the 1-1/2-D time-dependent plasma transport code WHIST. The former code contains the best available treatment of neutral-particle physics, including a selection of wall reflection models. The latter code has a comprehensive set of plasma transport coefficients, an MHD equilibrium package, and provision for source terms such as tho… more
Date: September 1, 1984
Creator: Boley, C. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Sub-microsecond beam notching at low energy

Description: A technique for creating a burst of 100 ns notches (beam extinctions) in an H{sup -} beam at 454 kHz has been developed at {le} 20 keV utilizing a Magnetron ion source with a slit extraction system and a split extractor. Each half of the extractor is treated as part of a 50 ohm transmission line which can be pulsed at {+-} 700 volts creating a 1400 volt gradient across the extractor. A beam current reduction of better than 95% has been observed at the end of the Fermilab 400 MeV Linac. Notched … more
Date: September 1, 2005
Creator: Moehs, D. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Experimental measurements of negative hydrogen ion production from surfaces

Description: Experimental measurements of the production of H/sup -/ from surfaces bombarded with hydrogen are reviewed. Some measurements of H/sup +/ and H/sup 0/ production from surfaces are also discussed with particular emphasis on work which might be relevant to ion source applications.
Date: September 1, 1977
Creator: Graham, W. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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D- production by backscattering from clean alkali-metal surfaces

Description: Measurements have been made of the total back-scattered D/sup -/ yields from Cs, Rb, K, Na and Li surfaces bombarded with D/sub 2//sup +/ and D/sub 3//sup +/ in the energy range 0.05 to 3.5 keV/nucleon. All measurements were made at a background pressure less than 10/sup -9/ Torr and the alkali-metal surfaces were evaporated onto a substrate in situ to assure uncontaminated surfaces. For each target, the D/sup -/ yield is at a maximum (as high as 12% per incident deuteron for Cs) between 150 an… more
Date: September 1, 1977
Creator: Schneider, P. J.; Berkner, K. H.; Graham, W. G.; Pyle, K. V. & Stearns, J. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest

Description: State selective nl-electron capture cross sections are presented for highly charged ions with Z = 6-10 colliding with atoms and molecules. The energy range investigated was from 1 eV/amu (v = 0.006 a.u.) to 100 keV/amu (v =2.0 a.u.). The energy dependence of the l-level populations is investigated. The K-shell x-ray emission cross sections are determined by using the calculated state-selective electron capture results as input and then applying hydrogenic branching and cascading values for the … more
Date: September 19, 2005
Creator: Otranto, S; Olson, R E & Beiersdorfer, P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Expressions for Form Factors for Inelastic Scattering and Charge Exchange in Plane-Wave, Distorted-Wave, and Coupled-Channels Reaction Formalisms

Description: This document is intended to facilitate calculation of inelastic scattering and charge-exchange cross sections in a variety of reaction models, including the plane-wave and distorted-wave approximations and the full coupled-channels treatments. Expressions are given for the coupling potentials between the relevant channels in both coordinate and momentum space. In particular, it is expected that the plane-wave calculations should be useful as a check on the correctness of coupled-channels calcu… more
Date: September 25, 2006
Creator: Dietrich, F S
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Detection of RF Perturbations Using an Ion Beam Diagnostic

Description: A Heavy Ion Beam Probe, HIBP, has been installed on a helicon plasma device. The objective was to measure plasma fluctuations at the 13.55MHz RF frequency. This offers a unique challenge for the HIBP, because the transit time of the probing ion is long compared to the fluctuations of interest. For previous HIBPs, the transit time has been short compared to the period of the fluctuations which permits one to assume that the magnetic and electric fields are static. Modeling has shown that the dia… more
Date: September 21, 2005
Creator: Schoch, P.; Connor, K. & Si, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Intense Pulsed Ion Neutral Source (IPINS)

Description: An Intense Pulsed Ion Neutral Source (IPINS) is being developed for injection into a mirror confinement experiment. The ion source is based on the reflex triode principle. The parameters achieved in current small-scale experiments are pulse duration 1 ..mu..s, beam energy 80 keV, and ion current density approximately 0.2 kA/cm/sup 2/. Beam neutralization using thin carbon foils is under investigation.
Date: September 30, 1977
Creator: Prono, D. S.; Ishizuka, H. & Briggs, R. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Analysis of the plasma sweeper

Description: The coupling of lower hybrid waves to a plasma can be modified by placing potentials on electrodes near the mouth of a phased array. Positive potentials on the electrodes create an electric field that sweeps the plasma away at a velocity c anti E x anti B/B/sup 2/. In this paper we derive the electric field created by the applied potential from the nondivergent character of the current flow and the ion momentum equation, in which ion-neutral charge-exchange collisions are retained, and we compa… more
Date: September 1, 1982
Creator: Glanz, J. & Motley, R. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Advanced neutral-beam technology

Description: Extensive development will be required to achieve the 50- to 75-MW, 175- to 200-keV, 5- to 10-sec pulses of deuterium atoms envisioned for ETF and INTOR. Multi-megawatt injector systems are large (and expansive); they consist of large vacuum tanks with many square meters of cryogenic pumping panels, beam dumps capable of dissipating several megawatts of un-neutralized beam, bending magnets, electrical power systems capable of fast turnoff with low (capacity) stored energy, and, of course, the i… more
Date: September 1, 1980
Creator: Berkner, K.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Another look at photodetachment of negative deuterium ions in neutral beam injectors

Description: Photodetachment is more desirable than other types of neutralizers of negative deuterium ions because it is cleaner, produces no gas or vapor, selectively detaches D/sup -/ and not heavy impurities, and may be more efficient. However, good overall efficiency in comparison with the alternatives is attainable only under the appropriate conditions of ion beam current density and thickness and with sufficient efficiencies of the laser and of the mirrors of the optical cavity. Analysis of these cond… more
Date: September 29, 1980
Creator: Fink, J.H. & Hamilton, G.W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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