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Sample records for charge exchange losses

  1. Transport, charge exchange and loss of energetic heavy ions in the earth's radiation belts - Applicability and limitations of theory

    NASA Technical Reports Server (NTRS)

    Spjeldvik, W. N.

    1981-01-01

    Computer simulations of processes which control the relative abundances of ions in the trapping regions of geospace are compared with observations from discriminating ion detectors. Energy losses due to Coulomb collisions between ions and exospheric neutrals are considered, along with charge exchange losses and internal charge exchanges. The time evolution of energetic ion fluxes of equatorially mirroring ions under radial diffusion is modelled to include geomagnetic and geoelectric fluctutations. Limits to the validity of diffusion transport theory are discussed, and the simulation is noted to contain provisions for six ionic charge states and the source effect on the radiation belt oxygen ion distributions. Comparisons are made with ion flux data gathered on Explorer 45 and ISEE-1 spacecraft and results indicate that internal charge exchanges cause the radiation belt ion charge state to be independent of source charge rate characteristics, and relative charge state distribution is independent of the radially diffusive transport rate below the charge state redistribution zone.

  2. The loss rates of O{sup +} in the inner magnetosphere caused by both magnetic field line curvature scattering and charge exchange reactions

    SciTech Connect

    Ji, Y.; Shen, C.

    2014-03-15

    With consideration of magnetic field line curvature (FLC) pitch angle scattering and charge exchange reactions, the O{sup +} (>300 keV) in the inner magnetosphere loss rates are investigated by using an eigenfunction analysis. The FLC scattering provides a mechanism for the ring current O{sup +} to enter the loss cone and influence the loss rates caused by charge exchange reactions. Assuming that the pitch angle change is small for each scattering event, the diffusion equation including a charge exchange term is constructed and solved; the eigenvalues of the equation are identified. The resultant loss rates of O{sup +} are approximately equal to the linear superposition of the loss rate without considering the charge exchange reactions and the loss rate associated with charge exchange reactions alone. The loss time is consistent with the observations from the early recovery phases of magnetic storms.

  3. Energy-loss cross sections for inclusive charge-exchange reactions at intermediate energies

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Dubey, Rajendra R.

    1993-01-01

    Charge-exchange reactions for scattering to the continuum are considered in a high-energy multiple scattering model. Calculations for (p,n) and (He-3,H-3) reactions are made and compared with experimental results for C-12, O-16, and Al-27 targets. Coherent effects are shown to lead to an important role for inelastic multiple scattering terms when light projectiles are considered.

  4. Charge exchange system

    DOEpatents

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  5. Electron-Nuclear Dynamics of atomic and molecular collisions: Charge exchange and energy loss

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, Remigio; Sabin, John R.; Ohrn, Yngve; Deumens, Erik

    2004-05-01

    Processes like electron exchange (capture and loss), bond breaking, and chemical reactions are difficult to visualize and treat in a time-independent approach. In this work, we present the Electron-Nuclear Dynamics (END) method for the study of time-dependent scattering processes. The END is a general approach for treating time-dependent problems which includes the dynamics of electrons and nuclei simultaneously by considering the full electron-nuclear coupling in the system and thus eliminates the necessity of constructing potential-energy surfaces. The theory approximates the time dependent Schrödinger equation starting from the time dependent variational principle (TDVP) by deriving a Hamiltonian dynamical system for time dependent nuclear and electronic wave function parameters. The wave function is described in a coherent state manifold, which leads to a system of Hamilton's equations of motion. The resulting system of coupled, first order, ordinary differential equations approximates the Schrödinger equation. A detailed analysis of the END equations is given for the case of a single-determinantal state for the electrons and a classical treatment of the nuclei. Emphasis is put on electron exchange, differential cross section and energy loss (stopping cross section) of collision of ions, atoms and molecules involving H, He, C, N, O, and Ne atoms. We compare our results to available experimental data.

  6. Electron-Nuclear Dynamics of collision processes: Charge exchange and energy loss

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, Remigio; Sabin, John R.; Öhrn, Yngve; Deumens, Erik

    2004-03-01

    We present the Electron-Nuclear Dynamics (END) method for the study of time-dependent scattering processes. The END is a general approach for treating time-dependent problems which includes the dynamics of electrons and nuclei simultaneously by considering the full electron-nuclear coupling in the system and thus eliminates the necessity of constructing potential-energy surfaces. The theory approximates the time dependent Schrödinger equation starting from the time dependent variational principle by deriving a Hamiltonian dynamical system for time dependent nuclear and electronic wave function parameters. The wave function is described in a coherent state manifold, which leads to a system of Hamilton's equations of motion. Emphasis is put on electron exchange, differential cross section and energy loss (stopping cross section) of collision of ions, atoms and molecules involving H, He, C, N, O, and Ne atoms. We compare our results to available experimental data.

  7. Localization of the large-angle foil-scattering beam loss caused by the multiturn charge-exchange injection

    NASA Astrophysics Data System (ADS)

    Kato, Shinichi; Yamamoto, Kazami; Yoshimoto, Masahiro; Harada, Hiroyuki; Kinsho, Michikazu

    2013-07-01

    In the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, significant losses were observed at the branching of the H0 dump line and the beam position monitor that was inserted downstream of the H0 dump branch duct. These losses were caused by the large-angle scattering of the injection and circulating beams at the charge-exchange foil. To realize high-power operation, these losses must be mitigated. Therefore, a new collimation system was developed and installed in October 2011. To efficiently optimize this system, the behavior of particles scattered by the foil and produced by the absorber were simulated, and the optimal position and angle of the absorber were investigated. During this process, an angle regulation method for the absorber was devised. An outline of this system, the angle regulation method for the absorber, and the performance of this new collimation system are described.

  8. Charge exchange molecular ion source

    DOEpatents

    Vella, Michael C.

    2003-06-03

    Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

  9. Ring current proton decay by charge exchange

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Fritz, T.

    1975-01-01

    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles.

  10. Charge Exchange with Highly Charged Ions

    NASA Astrophysics Data System (ADS)

    Glick, Jeremy; Ferri, Kevin; Schmitt, Jaclyn; Hanson, Joshua; Marler, Joan

    2016-05-01

    A detailed study of the physics of highly charged ions (HCIs) is critical for a deep understanding of observed phenomena resulting from interactions of HCIs with neutral atoms in astrophysical and fusion environments. Specifically the charge transfer rates and spectroscopy of the subsequent decay fluorescence are of great interest to these communities. Results from a laboratory based investigation of these rates will be presented. The experiment takes advantage of an energy and charge state selected beam of HCIs from the recently on-line Clemson University EBIT (CUEBIT). Progress towards an experimental apparatus for retrapping HCIs towards precision spectroscopy of HCIs will also be presented.

  11. PLT and PDX perpendicular charge exchange analyzers

    NASA Astrophysics Data System (ADS)

    Mueller, D.; Hammett, G. W.; McCune, D. C.

    1986-08-01

    The perpendicular charge-exchange systems used on the poloidal divertor experiment and the Princeton large torus are comprised of ten-channel, mass-resolved, charge-exchange analyzers. Results from these systems indicate that instrumental effects can lead to erroneous temperature measurements during deuterium neutral beam injection or at low hydrogen concentrations.

  12. Charge exchange in H^+ + He^+ collision

    NASA Astrophysics Data System (ADS)

    Guevara Leon, Nicolais; Sabin, John R.; Deumens, Erik; Ohrn, Yngve

    2008-05-01

    Charge exchange in H^+ + He^+ collision are investigated theoretically at projectile energies below the ionization threshold at about 100 keV/amu. The electron nuclear dynamics (END) method is used to analyze the collision processes. Total charge exchange cross sections were calculated and compared with other theoretical and experimental data.

  13. Charge exchange in zinc-neon

    NASA Technical Reports Server (NTRS)

    Chubb, D. L.

    1975-01-01

    Excitation of the 4d and 5p levels of Zn+ by charge exchange bewteen Ne+ and Zn was investigated. From measured electron temperature and line intensity ratios it was concluded that charge exchange is the dominate mechanism for populating the 4d2D5/2 level of Zn+. Comparison of Zn-Ne and Zn-Ar results imply the same conclusion. No evidence for charge exchange as the dominant pumping mechanism for the 5p2Pl/2, 5p2P3/2, or 4d2D3/2 levels was obtained.

  14. Facility produced charge-exchange ions

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1981-01-01

    These facility produced ions are created by charge-exchange collisions between neutral atoms and energetic thruster beam ions. The result of the electron transfer is an energetic neutral atom and an ion of only thermal energy. There are true charge-exchange ions produced by collisions with neutrals escaping from the ion thruster and being charge-exchange ionized before the neutral intercepts the tank wall. The facility produced charge-exchange ions will not exist in space and therefore, represent a source of error where measurements involving ion thruster plasmas and their density are involved. The quantity of facility produced ions in a test chamber with a 30 cm mercury ion thruster was determined.

  15. Pion double charge exchange and hadron dynamics

    SciTech Connect

    Johnson, M.B.

    1991-01-01

    This paper will review theoretical results to show how pion double charge exchange is contributing to our understanding of hadron dynamics in nuclei. The exploitation of the nucleus as a filter is shown to be essential in facilitating the comparison between theory and experiment. 23 refs., 3 figs., 2 tabs.

  16. Characteristics of solid-target charge-exchange analyzers for energetic ion diagnostics on tokamaks

    SciTech Connect

    Beiersdorfer, P.; Roquemore, A.L.; Kaita, R.

    1987-05-01

    Compact electrostatic charge-exchange analyzers have been constructed for installation in areas of high magnetic fields and restricted access near tokamak fusion devices. The analyzers employed carbon stripping foils, and have been calibrated for proton energies between 1 and 70 keV. They have been successfully used to study charge-exchange losses in auxiliary-heated tokamak plasmas.

  17. Charge exchange avalanche at the cometopause

    NASA Technical Reports Server (NTRS)

    Gombosi, Tamas I.

    1987-01-01

    A sharp transition from a solar wind proton dominated flow to a plasma population primarily consisting of relatively cold cometary heavy ions has been observed at a cometocentric distance of about 160,000 km by the VEGA and GIOTTO missions. This boundary (the cometopause) was thought to be related to charge transfer processes, but its location and thickness are inconsistent with conventionally estimated ion - neutral coupling boundaries. In this paper a two-fluid model is used to investigate the major physical processes at the cometopause. By adopting observed comet Halley parameters the model is able to reproduce the location and the thickness of this charge exchange boundary.

  18. Charge-exchange plasma environment for an ion drive spacecraft

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Carruth, M. R., Jr.

    1981-01-01

    A model was reviewed which describes the propagation of the mercury charge-exchange plasma and extended to describe the flow of the molybdenum component of the charge-exchange plasma. The uncertainties in the models for various conditions are discussed. Such topics as current drain to the solar array, charge-exchange plasma material deposition, and the effects of space plasma on the charge-exchange plasma propagation are addressed.

  19. Charge exchange in solar wind-cometary interactions

    NASA Technical Reports Server (NTRS)

    Gombosi, T. I.; Horanyi, M.; Kecskemety, K.; Cravens, T. E.; Nagy, A. F.

    1983-01-01

    A simple model of a cometary spherically symmetrical atmosphere and ionosphere is considered. An analytic solution of the governing equations describing the radial distribution of the neutral and ion densities is found. The new solution is compared to the well-known solution of the equations containing only ionization terms. Neglecting recombination causes a significant overestimate of the ion density in the vicinity of the comet. An axisymmetric model of the solar wind-cometary interaction is considered, taking into account the loss of solar wind ions due to charge exchange. The calculations predict that for active comets, solar wind absorption due to charge exchange becomes important at a few thousand kilometers from the nucleus, and a surface separating the shocked solar wind from the cometary ionosphere develops in this region. These calculations are in reasonable agreement with the few observations available for the ionopause location at comets.

  20. Scanning energy analyzer of charge exchange atoms

    SciTech Connect

    Rogozin, A.I.; Shikhovtsev, I.V.

    1994-12-31

    The construction, operation principle, and parameters of multichannel scanning energy analyzer of charge exchange atoms are discussed. The analyzer is used to measure the splashing ion angular distribution and energy spectra, the ions being produced in a gas dynamic plasma trap (GDCS) during the injection of powerful atomic hydrogen beam into preliminary produced plasma with density n {approx_equal} 5 {times} 10{sup 13} cm{sup {minus}3}. The parameters of the hydrogen beam are as follows: particle energy -50 keV, equivalent current -250 A, pulse duration -1 ms. The device can be also used for measurements of energy spectra of atomic and charged particle beams in plasma diagnostics, beam physics, and physics of atomic collisions. 4 refs., 4 figs.

  1. Ion thruster charge-exchange plasma flow

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.; Gabriel, S. B.; Kitamura, S.

    1982-01-01

    The electron bombardment ion thruster has been under development for a number of years and during this time, studies of the plasmas produced by the thrusters and their interactions with spacecraft have been evaluated, based on available data. Due to diagnostic techniques used and facility effects, there is uncertainty as to the reliability of data from these early studies. This paper presents data on the flow of the charge-exchange plasma produced just downstream of the thruster's ion optics. The 'end-effect' of a cylindrical Langmuir probe is used to determine ion density and directed ion velocity. Results are compared with data obtained from a retarding potential analyzer-Faraday cup.

  2. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  3. Visible charge exchange recombination spectroscopy on TFTR

    SciTech Connect

    Stratton, B.C.; Fonck, R.J.; Jaehnig, K.P.; Schechtman, N.; Synakowski, E.J.

    1991-03-01

    Visible charge exchange recombination spectroscopy is routinely used to measure the time evolution of the ion temperature (T{sub i}) and toroidal rotation velocity (v{sub {phi}}) profiles on TFTR. These measurements are made with the CHERS diagnostic, a fiber-optically coupled spectrometer equipped with a two-dimensional photodiode array detector which provides both spectral and spatial resolution. The instrumentation, data analysis techniques, and examples of T{sub i} and v{sub {phi}} measurements are described. Recently, CHERS has been used to perform impurity transport experiments: radial profiles of diffusivities and convective velocities for helium and iron have been deduced from measurements of the time evolutions of He{sup 2+} and Fe{sup 24+} profiles following impurity injection. Examples of these measurements are given. 12 refs., 8 figs.

  4. Systematics of pion double charge exchange

    SciTech Connect

    Gilman, R.A.

    1985-10-01

    Differential cross sections have been measured for pion-induced double-charge-exchange (DCX) reactions leading to double-isobaric-analog states (DIAS) and low-lying nonanalog states in the residual nuclei. A description of the experimental details and data analysis is presented. The experimentally observed systematics of reactions leading to DIAS, to nonanalog ground states, and to low-lying 2 states are described. Lowest-order optical-model calculations of DIAS DCX are compared to the data. Efforts to understand the anomalies by invoking additional reaction-mechanism amplitudes and a higher-order optical potential are described. Calculations of nonanalog DCX reactions leading to J/sup / = 0 states were performed within a distorted-wave impulse-approximation framework. The sensitivities of these calculations to input parameters are discussed. 58 refs., 41 figs., 16 tabs.

  5. Dependence of the charge exchange lifetimes on mirror latitude

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Bewtra, N. K.

    1976-01-01

    The dependence of the charge exchange lifetimes on the mirror latitude for ions mirroring off the geomagnetic equator was re-computed using the improved hydrogen distribution models. The Chamberlain model was used to define the spatial distribution of the neutral hydrogen environment through which the ring current ions traverse. The resultant dependence of the charge exchange lifetime on mirror latitude is best fitted by the approximation that contains the charge exchange lifetime for equatorial particles.

  6. PLT and PDX perpendicular charge-exchange analyzers

    SciTech Connect

    Mueller, D.; Hammett, G.W.; McCune, D.C.

    1986-08-01

    The perpendicular charge-exchange systems used on the poloidal divertor experiment and the Princeton large torus are comprised of ten-channel, mass-resolved, charge-exchange analyzers. Results from these systems indicate that instrumental effects can lead to erroneous temperature measurements during deuterium neutral beam injection or at low hydrogen concentrations.

  7. Suzaku Observations of Charge Exchange Emission from Solar System Objects

    NASA Technical Reports Server (NTRS)

    Ezoe, Y.; Fujimoto, R.; Yamasaki, N. Y.; Mitsuda, K.; Ohashi, T.; Ishikawa, K.; Oishi, S.; Miyoshi, Y; Terada, N.; Futaana, Y.; Porter, F. S.; Brown, G. V.

    2012-01-01

    Recent results of charge exchange emission from solar system objects observed with the Japanese Suzaku satellite are reviewed. Suzaku is of great importance to investigate diffuse X-ray emission like the charge exchange from planetary exospheres and comets. The Suzaku studies of Earth's exosphere, Martian exosphere, Jupiter's aurorae, and comets are overviewed.

  8. Double charge exchange at high impact energies

    NASA Astrophysics Data System (ADS)

    Belkić, Dževad

    1994-03-01

    In fast ion-atom collisions, double ionization always dominates the two-electron transfer. For this reason, an adequate description of double charge exchange requires proper inclusion of intermediate ionization channels. This is even more important in two- than in one-electron transitions. First-order Born-type perturbation theories ignore throughout these electronic continuum intermediate states and hence provide utterly unreliable high energy cross sections for two-electron capture processes. Therefore, it is essential to use second- and higher-order theories, which include the intermediate ionization continua of the two electrons in an approximate manner. In the present paper, a new second-order theory called the Born distorted wave (BDW) approximation is introduced and implemented in the case of symmetric resonant double electron capture from the ground state of helium by fast alpha particles. A genuine four-body formalism is adopted, in contrast to the conventional independent particle model of atomic scattering theory. The obtained results for the total cross sections are compared with the available experimental data, and satisfactory agreement is recorded. As the incident energy increases, a dramatic improvement is obtained in going from the CB1 to the BDW approximation, since the latter closely follows the measurement, whereas the former overestimates the observed total cross sections by two orders of magnitude. This strongly indicates that the role of continuum intermediate states is decisive, even at those incident energies for which the Thomas double scattering effects are not important. This is in sharp contrast to the case of one-electron transfer atomic reactions.

  9. X-ray emission from charge exchange of highly-charged ions in atoms and molecules

    NASA Technical Reports Server (NTRS)

    Greenwood, J. B.; Williams, I. D.; Smith, S. J.; Chutjian, A.

    2000-01-01

    Charge exchange followed by radiative stabilization are the main processes responsible for the recent observations of X-ray emission from comets in their approach to the Sun. A new apparatus was constructed to measure, in collisions of HCIs with atoms and molecules, (a) absolute cross sections for single and multiple charge exchange, and (b) normalized X-ray emission cross sections.

  10. Charge-exchange plasma generated by an ion thruster

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1977-01-01

    The charge exchange plasma generated by an ion thruster was investigated experimentally using both 5 cm and 15 cm thrusters. Results are shown for wide ranges of radial distance from the thruster and angle from the beam direction. Considerations of test environment, as well as distance from the thruster, indicate that a valid simulation of a thruster on a spacecraft was obtained. A calculation procedure and a sample calculation of charge exchange plasma density and saturation electron current density are included.

  11. 78 FR 28137 - Exchange Visitor Program-Fees and Charges

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    ..., 2013 (RIN 1400-AD28; 78 FR 6263), with a request for comments, to amend 22 CFR 62.17 (``Fees and... Part 62 RIN 1400-AD28 Exchange Visitor Program--Fees and Charges AGENCY: Department of State. ACTION... Application Fee for Sponsor Designation or Redesignation and the Administrative Fee for Exchange Visitor...

  12. Metal loss and charge heating in the melt in an electric arc furnace

    NASA Astrophysics Data System (ADS)

    Serikov, V. A.; Bikeev, R. A.; Cherednichenko, M. V.; Cherednichenko, V. S.

    2015-12-01

    The heat exchange between a metallic melt and a slag with a charge is simulated with allowance for possible formation of a skull on the charge surface. It is shown that the charge melting rate in the melt is determined by the coefficient of heat transfer between the metal and the charge and the ratio of the mass of a charge fragment to its surface area interacting with the melt. A skull is found to form on the charge surface at a low coefficient of heat transfer between the metal and the charge. The main heat parameters, the control of which by an automatic control system ensures an increase in the charge melting rate in the melt and a decrease in the metal loss, are formulated.

  13. 76 FR 10498 - Exchange Visitor Program-Fees and Charges

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-25

    ... rule, Public Notice 7077 at 75 FR 60674-60679, October 1, 2010, with a request for comments, amending... Part 62 RIN 1400-AC67 Exchange Visitor Program--Fees and Charges AGENCY: Department of State. ACTION: Final rule. SUMMARY: The Department of State is amending its regulations regarding fees and charges...

  14. Characterization of various losses in a cryogenic counterflow heat exchanger

    NASA Astrophysics Data System (ADS)

    Aminuddin, Mohammad; Zubair, Syed M.

    2014-11-01

    A detailed assessment of irreversibility, predominantly heat in-leak and axial wall conduction, is essential in accurately predicting the performance of high effectiveness heat exchangers employed in cryogenic applications. Integration into a refrigeration system as well requires consideration of parasitic heat loss by conduction from exchanger cold end to the adjacent components. Governing equations incorporating these effects in a counterflow exchanger are solved numerically and the model predictions evaluated for heat exchanger ineffectiveness and heat loss by conduction. The optimum performance mandates minimization of both. Although ineffectiveness decreases at higher longitudinal conduction, cold end loss increases with deterioration of the overall performance. Utilizing lower heat capacity rate hot fluid, nevertheless, reduces the cold end loss. Heat in-leak is relatively high with concurrent consideration of axial wall conduction and has adverse consequence on heat exchanger effectiveness. Analysis of the net heat transferred to lower stages of refrigeration reveals a critical NTU.

  15. Characterization of an atomic hydrogen source for charge exchange experiments

    NASA Astrophysics Data System (ADS)

    Leutenegger, M. A.; Beiersdorfer, P.; Betancourt-Martinez, G. L.; Brown, G. V.; Hell, N.; Kelley, R. L.; Kilbourne, C. A.; Magee, E. W.; Porter, F. S.

    2016-11-01

    We characterized the dissociation fraction of a thermal dissociation atomic hydrogen source by injecting the mixed atomic and molecular output of the source into an electron beam ion trap containing highly charged ions and recording the x-ray spectrum generated by charge exchange using a high-resolution x-ray calorimeter spectrometer. We exploit the fact that the charge exchange state-selective capture cross sections are very different for atomic and molecular hydrogen incident on the same ions, enabling a clear spectroscopic diagnostic of the neutral species.

  16. Charge Exchange Spectra of Hydrogenic and He-like Iron

    SciTech Connect

    Wargelin, B J; Beiersdorfer, P; Neill, P A; Olson, R E; Scofield, J H

    2005-04-27

    We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra resulting from collisions of highly charged iron with N{sub 2} gas at an energy of {approx}10 eV amu{sup -1} in an electron beam ion trap. Although high-n emission lines are not resolved in our measurements, we observe that the most likely level for Fe{sup 25+} {yields} Fe{sup 24+} electron capture is n{sub max} {approx} 9, in line with expectations, while the most likely value for Fe{sup 26+} {yields} Fe{sup 25+} charge exchange is significantly higher. In the Fe XXV spectrum, the K{alpha} emission feature dominates, whether produced via charge exchange or collisional excitation. The K{alpha} energy centroid is lower in the former case than the latter (6666 versus 6685 eV, respectively), as expected because of the strong enhancement of emission from the forbidden and intercombination lines, relative to the resonance line, in charge-exchange spectra. In contrast, the Fe XXVI high-n Lyman lines have a summed intensity greater than that of Ly{alpha}, and are substantially stronger than predicted from theoretical calculations of charge exchange with atomic H. A discussion is presented of the relevance of our results to studies of diffuse Fe emission in the Galactic Center and Galactic Ridge, particularly with ASTRO-E2.

  17. Charge exchange of a polar molecule at its cation

    SciTech Connect

    Buslov, E. Yu. Zon, B. A.

    2011-01-15

    The Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a {sigma}-electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particles. The resonant charge-transfer cross section is calculated, and the effect of the dipole moments of the core on the cross section is analyzed. It is shown that allowance for the dependence of the exchange potential on the orientation of the dipole moments relative to the molecular axis may change the dependence of the cross section on the velocity of colliding particles, which is typical of the resonant charge exchange, from the resonance to the quasi-resonance dependence.

  18. Controlled charge exchange between alkaline earth metals and their ions

    NASA Astrophysics Data System (ADS)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be<-->9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  19. Charge-exchange born He(+) ions in the solar wind

    NASA Technical Reports Server (NTRS)

    Gruntman, Michael A.

    1992-01-01

    The effect of charge transfer between solar wind alpha-particles and hydrogen atoms of interstellar origin is revisited. Singly-charged helium ions born in the charge transfer carry important information on processes in the solar wind and the heliosphere. The velocity distribution of such He(+) ions is substantially different from that of He(+) pick-up ions due to ionization of the interstellar helium atoms. Estimates of the expected abundances of the charge-exchange born He(+) in the solar wind are presented, and the possibility of measuring this plasma component on deep space missions is discussed.

  20. Charge-exchange born He(+) ions in the solar wind

    NASA Astrophysics Data System (ADS)

    Gruntman, Michael A.

    1992-07-01

    The effect of charge transfer between solar wind alpha-particles and hydrogen atoms of interstellar origin is revisited. Singly-charged helium ions born in the charge transfer carry important information on processes in the solar wind and the heliosphere. The velocity distribution of such He(+) ions is substantially different from that of He(+) pick-up ions due to ionization of the interstellar helium atoms. Estimates of the expected abundances of the charge-exchange born He(+) in the solar wind are presented, and the possibility of measuring this plasma component on deep space missions is discussed.

  1. Ion temperatures in HIP-1 and SUMMA from charge-exchange neutral optical emission spectra

    NASA Technical Reports Server (NTRS)

    Patch, R. W.; Lauver, M. R.

    1976-01-01

    Ion temperatures were obtained from observations of the H sub alpha, D sub alpha, and He 587.6 nm lines emitted from hydrogen, deuterium, and helium plasmas in the SUMMA and HIP-1 mirror devices at Lewis Research Center. Steady state discharges were formed by applying a radially inward dc electric field between cylindrical or annular anodes and hollow cathodes located at the peaks of the mirrors. The ion temperatures were found from the Doppler broadening of the charge-exchange components of spectral lines. A statistical method was developed for obtaining scaling relations of ion temperature as a function of current, voltage, and magnetic flux density. Derivations are given that take into account triangular monochromator slit functions, loss cones, and superimposed charge-exchange processes. In addition, the Doppler broadening was found to be sensitive to the influence of drift on charge-exchange cross section. The effects of finite ion-cyclotron radius, cascading, and delayed emission are reviewed.

  2. Radiocarbon detection by ion charge exchange mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hotchkis, Michael; Wei, Tao

    2007-06-01

    A method for detection of radiocarbon at low levels is described and the results of tests are presented. We refer to this method as ion charge exchange mass spectrometry (ICE-MS). The ICE-MS instrument is a two stage mass spectrometer. In the first stage, molecular interferences which would otherwise affect radiocarbon detection at mass 14 are eliminated by producing high charge state ions directly in the ion source (charge state ⩾2). 14N interference is eliminated in the second stage by converting the beam to negative ions in a charge exchange cell. The beam is mass-analysed at each stage. We have built a test apparatus consisting of an electron cyclotron resonance ion source and a pair of analysing magnets with a charge exchange cell in between, followed by an electrostatic analyser to improve the signal to background ratio. With this apparatus we have measured charge exchange probabilities for (Cn+ → C-) from 4.5 to 40.5 keV (n = 1-3). We have studied the sources of background including assessment of limits for nitrogen interference by searching for negative ions from charge exchange of 14N ions. Our system has been used to detect 14C in enriched samples of CO2 gas with 14C/12C isotopic ratio down to the 10-9 level. Combined with a measured sample consumption rate of 4 ng/s, this corresponds to a capability to detect transient signals containing only a few μBq of 14C activity, such as may be obtained from chromatographic separation. The method will require further development to match the sensitivity of AMS with a gas ion source; however, even in its present state its sensitivity is well suited to tracer studies in biomedical research and drug development.

  3. Instability of the heliopause driven by charge exchange interactions

    SciTech Connect

    Avinash, K.; Zank, G. P.; Dasgupta, B.; Bhadoria, Shikha

    2014-08-20

    The stability of the heliopause that separates the tenuous hot magnetized heliosheath plasma from the dense cool local interstellar magnetized plasma is examined using a fully general model that includes all the essential physical processes. Charge exchange coupling between plasma protons and primary interstellar neutral atoms provides an effective gravity that drives Rayleigh-Taylor (RT)-like instabilities. The velocity difference or shear between the heliosheath and interstellar flows, when coupled to energetic neutral atoms (ENAs), drives a Kelvin-Helmholtz (KH)-like instability on the heliopause. The shoulder region of the heliopause is unstable to a new instability that has characteristics of a mixed RT-KH-like mode. The instabilities are not stabilized by typical values of the magnetic fields in the inner and outer heliosheath (OHS). ENAs play an essential role in driving the KH-like instability, which is fully stabilized in their absence by magnetic fields. The nonlinear phase of these instabilities is briefly discussed. We also discuss the possibility that RT-like or mixed KH-RT-like instabilities drag outer heliosheath/very local interstellar medium (OHS/VLISM) magnetic field lines into the inner heliosheath (IHS) with the VLISM flow, and the possibility that IHS and VLISM magnetic field lines experience reconnection. Such reconnection may (1) greatly enhance the mixing of plasmas across the heliopause and (2) provide open magnetic field lines that allow easy ingress of galactic cosmic rays into the heliosphere and corresponding easy loss of anomalous cosmic rays from the heliosphere.

  4. Oscillating flow loss test results in Stirling engine heat exchangers

    NASA Technical Reports Server (NTRS)

    Koester, G.; Howell, S.; Wood, G.; Miller, E.; Gedeon, D.

    1990-01-01

    The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.

  5. Charge exchange processes involving highly charged ions and targets of interest in astrophysics and fusion plasmas

    NASA Astrophysics Data System (ADS)

    Otranto, S.

    2012-11-01

    Renewed interest in charge exchange processes involving highly charged ions arises because of their crucial role in the planned ITER reactor as well as to recent X-ray observations in the astrophysical context. In this work, the classical trajectory Monte Carlo method (CTMC) is used to calculate state selective single charge exchange n-level cross sections and line emission cross sections pertinent to both fields. These are contrasted to recent laboratory data from KVI for the Xe18+ + Na(3s) collision system and NIST/BERLIN-EBIT data for the Ar18+ +Ar system.

  6. Development of the charge exchange type beam scraper system at the J-PARC

    NASA Astrophysics Data System (ADS)

    Okabe, K.; Yamamoto, K.; Kinsho, M.

    2016-03-01

    Improvement in injection beam quality at the Japan Proton Accelerator Research Complex 3-GeV rapid cycle synchrotron is to mitigate beam loss at the injection section. We developed a charge-exchange type scraper system with a thin carbon foil to collimate the beam halo in the injection beam line of the synchrotron. The key issue to realize the scraper is a reduction of the beam loss induced by the multiple-scattering effect of charge-exchange foil placed at the scraper head. In order to determine the adequate foil thickness, a charge-exchange efficiency of a carbon foil and particle-tracking simulation study of the collimated beam have been performed assuming a realistic halo at the scraper section. Using the results of this study, we chose the thickness of a 520 μg /cm2 as the scraper foils to mitigate radiation dose around the L3BT scraper section. A charge-exchange scraper system that prevents the emission of radioactive fragments of the carbon foil was build. The system was put into operation to prove its effectiveness in eliminating the beam halo. From the result of a preliminary beam experiments, we confirmed that the installed scrapers eliminate a transverse beam tail or halo. After two days of operation with beam collimation, the radiation dose level around the scraper section was a tolerable one for the hands-on maintenance.

  7. HIGH CURRENT D- PRODUCTION BY CHARGE EXCHANGE IN SODIUM

    SciTech Connect

    Hooper, E.B.; Poulsen, P.; Pincosy, P.A.

    1981-02-01

    A beam of D{sup -} ions has been produced at 7-13 keV, with currents up to 2.2 {angstrom}, using charge exchange in sodium vapor. The beam profile is bi-Gaussian with angular divergence 0.7{sup o} x 2.8{sup o} and peak current density 15 mA/cm{sup 2}. The characteristics of the beam are in excellent agreement with predictions based on atomic cross sections. The sodium vapor target is formed by a jet directed across the beam. The sodium density drops rapidly in the beamline downstream from the charge exchange region, decreasing three orders of magnitude in 15 cm. Measurement and analysis of the plasma accompanying the beam demonstrate that plasma densities nearly equal to the beam density are obtained 1 m from the charge exchange medium. The plasma produced in the sodium is thus well confined to the charge exchange region and does not propagate along the beam.

  8. Ion exchange and surface charge on montmorillonite clay

    SciTech Connect

    Sperry, J.M.; Peirce, J.J.

    1999-05-01

    An ion-exchange model originally developed for pure oxides prepared in the laboratory is extended to study of ion exchange and surface charge on a naturally occurring montmorillonite clay. The range of surface charges measured for montmorillonite with various electrolyte solutions and clay pretreatments is within the range of those measured for a wide variety of oxides prepared in the laboratory, including MnO{sub 2}-IC1, MnO{sub 2}-IC12, MnO{sub 2}-IC22, titanium dioxide, ferric oxide, and aluminum oxide. In addition, fitted parameter values for lateral interaction constants and equilibrium constants for the acid sites that characterize ion exchange on montmorillonite are on the same order of magnitude as those obtained for pure oxides. Surface charge of montmorillonite in sodium nitrate solution is measured to be approximately 15 to 25% greater than that measured between a pH of 4 and 9 in calcium chloride solution. This difference is attributed to the greater charge on the calcium (2{sup +}) ion; thus, its stronger electrostatic attraction to the acid hydroxyl site. An order of magnitude change in solids concentration (C{sub p}) can lead to a difference in measured net surface charge density of the same oxide sample of several orders of magnitude. This difference increases at higher pH, indicating the importance of reporting the corresponding C{sub p} at which experiments are conducted.

  9. Krypton charge exchange cross sections for Hall effect thruster models

    SciTech Connect

    Hause, Michael L.; Prince, Benjamin D.; Bemish, Raymond J.

    2013-04-28

    Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr{sup +} + Kr and Kr{sup 2+} + Kr cross sections. The measurements of symmetric Kr{sup +} + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr{sup 2+} + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr{sup 2+} + Kr {yields} Kr{sup +} + Kr{sup +} reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A{sup 2} with an exception near 70-80 eV.

  10. Charge state distributions and charge exchange cross sections of carbon in helium at 30-258 keV

    NASA Astrophysics Data System (ADS)

    Maxeiner, Sascha; Seiler, Martin; Suter, Martin; Synal, Hans-Arno

    2015-10-01

    With the introduction of helium stripping in radiocarbon (14C) accelerator mass spectrometry (AMS), higher +1 charge state yields in the 200 keV region and fewer beam losses are observed compared to nitrogen or argon stripping. To investigate the feasibility of even lower beam energies for 14C analyses the stripping characteristics of carbon in helium need to be further studied. Using two different AMS systems at ETH Zurich (myCADAS and MICADAS), ion beam transmissions of carbon ions for the charge states -1, +1, +2 and +3 were measured in the range of 258 keV down to 30 keV. The correction for beam losses and the extraction of charge state yields and charge exchange cross sections will be presented. An increase in population of the +1 charge state towards the lowest measured energies up to 75% was found as well as agreement with previous data from literature. The findings suggest that more compact radiocarbon AMS systems are possible and could provide even higher efficiency than current systems operating in the 200 keV range.

  11. A time-resolved study on the interaction of oppositely charged bicelles--implications on the charged lipid exchange kinetics.

    PubMed

    Yang, Po-Wei; Lin, Tsang-Lang; Hu, Yuan; Jeng, U-Ser

    2015-03-21

    Time-resolved small-angle X-ray scattering was applied to study charged lipid exchange between oppositely charged disc-shaped bicelles. The exchange of charged lipids gradually reduces the surface charge density and weakens the electrostatic attraction between the oppositely charged bicelles which form alternately stacked aggregates upon mixing. Initially, at a high surface charge density with almost no free water layer between the stacked bicelles, fast exchange kinetics dominate the exchange process. At a later stage with a lower surface charge density and a larger water gap between the stacked bicelles, slow exchange kinetics take over. The fast exchange kinetics are correlated with the close contact of the bicelles when there is almost no free water layer between the tightly bound bicelles with a charged lipid exchange time constant as short as 20-40 min. When the water gap becomes large enough to have a free water layer between the stacked bicelles, the fast lipid exchange kinetics are taken over by slow lipid exchange kinetics with time constants around 200-300 min, which are comparable to the typical time constant of lipid exchange between vesicles in aqueous solution. These two kinds of exchange mode fit well with the lipid exchange models of transient hemifusion for the fast mode and monomer exchange for the slow mode.

  12. Neutral Collisions and Charge Exchange in Titan's Exosphere

    NASA Astrophysics Data System (ADS)

    Sillanpää, I.; Johnson, R. E.

    2012-12-01

    Results from new hybrid simulations for Titan are presented. These simulations take into account the elastic collisions between ions and neutral gas as well as the charge exchange reactions for protons and oxygen ions. We used SRIM [1] cross sections for hydrogen and oxygen ions in nitrogen gas to calculate cross sections for the five ions species used in the HYB-Titan hybrid model [2, see also 3] (H+, H2+, O+, CH4+, and N2+). The N2 density profile used was from INMS measurements over a dozen flybys. In addition, we are studying the effect the charge transfer (CT) reactions for H+ and O+ leading to simple CT, dissociative CT and CT with ionization. All reaction cross sections are energy dependent. Neutral particles are not created, but the total ENA energy is recorded as well as the resulting reaction rates. The results show that both of neutral collisions and CT processes have a significant role in the development and shape of Titan's ionotail and wake structure. Results will be described in detail as well as the implications of the ion-neutral collisions for the heating of Titan's neutral corona and atmospheric escape [4]. References [1] Stopping and Range of Ions in Matter (SRIM), Monte Carlo software by James F. Ziegler (online at http://www.srim.org/ ) [2] Sillanpää, I., Hybrid Modelling of Titan's Interaction with the Magnetosphere of Saturn, Ph.D. dissertation, Finnish Meteorological Contributions, 68, Yliopistopaino, Helsinki, 2008. (online at http://urn.fi/URN:ISBN:978-951-697-660-3) [3] Sillanpää, I., D. Young, F. Crary, M. Thomsen, D. Reisenfeld, J-E.Wahlund, C. Bertucci, E. Kallio, R. Jarvinen, and P. Janhunen, Cassini Plasma Spectro:meter and Hybrid Model Study on Titan's Interaction: Effect of Oxygen Ions, J. Geophys. Res., doi:10.1029/2011JA016443, 2011. [4] Johnson, R.E., O.J. Tucker, M. Michael, E.C. Sittler, H.T. Smith, D.T. Young, and J.H. Waite, Mass Loss Processes in Titan's Upper Atmosphere, Chap. 15 in "Titan from Cassini-Huygens" (eds

  13. Pion double charge exchange scattering above the delta resonance

    SciTech Connect

    Burleson, G.R.

    1989-01-01

    Data are presented on pion-nucleus double-charge-exchange scattering at energies between 300 and 500 MeV, the highest energies measured so far, together with a review of results at lower energies. The small-angle excitation functions disagree with predictions based on a sex-quark cluster model and on an optical model consistent with single-charge-exchange scattering at these energies, but they are consistent with a distorted-wave calculation. Data on f{sub 7/2}-shell nuclei are in partial agreement with a two-amplitude model which is successful at lower energies. In order to achieve good understanding of this process at these energies, more work; both experimental and theoretical, is needed. 16 refs., 6 figs.

  14. Mass-resolving charge-exchange system on PDX

    SciTech Connect

    Davis, S.L.; Mueller, D.; Keane, C.J.

    1982-10-01

    The PDX charge-exchange system is comprised of four, ten channel, mass-resolved, charge-exchange analyzers. Each analyzer is constructed with parallel electric and magnetic fields and is calibrated over an energy range of 0.5 to 40 keV. The mass rejection between hydrogen and deuterium has been measured as better than 1000 to 1. For ohmic heated discharges the system can provide single shot radial ion temperature profiles (4 point) with 1 msec time resolution. For neutral beam heated discharges complete radial and temporal profiles can be obtained in 2 to 4 shots. The system is also equipped with a vertically aimed diagnostic neutral beam to allow local ion-energy distribution measurements. This report describes the analyzer system and its calibration, and presents results from ohmic and neutral beam heated discharges.

  15. Coherent population trapping probed by charge exchange reactions

    NASA Astrophysics Data System (ADS)

    Gieler, M.; Aumayr, F.; Windholz, L.

    1992-12-01

    Coherent trapping of atomic population in sodium induced by two-frequency laser light has been studied by using a charge exchange reaction for probing the upper level population. When the two-photon resonance condition occurs, the signal due to electron capture from excited Na*(3p) atoms by He2+ projectile ions exhibits the characteristic ``black resonance'' dip, indicating (by nonoptical means) that the fraction of Na atoms in the excited state actually drops to zero.

  16. Momentum transfer in relativistic heavy ion charge-exchange reactions

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Khan, F.; Khandelwal, G. S.

    1991-01-01

    Relativistic heavy ion charge-exchange reactions yield fragments (Delta-Z = + 1) whose longitudinal momentum distributions are downshifted by larger values than those associated with the remaining fragments (Delta-Z = 1, -2,...). Kinematics alone cannot account for the observed downshifts; therefore, an additional contribution from collision dynamics must be included. In this work, an optical model description of collision momentum transfer is used to estimate the additional dynamical momentum downshift. Good agreement between theoretical estimates and experimental data is obtained.

  17. Computer code for charge-exchange plasma propagation

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.; Kaufman, H. R.

    1981-01-01

    The propagation of the charge-exchange plasma from an electrostatic ion thruster is crucial in determining the interaction of that plasma with the associated spacecraft. A model that describes this plasma and its propagation is described, together with a computer code based on this model. The structure and calling sequence of the code, named PLASIM, is described. An explanation of the program's input and output is included, together with samples of both. The code is written in ASNI Standard FORTRAN.

  18. Imaging charge exchange recombination spectroscopy on the TEXTOR tokamak

    NASA Astrophysics Data System (ADS)

    Howard, J.; Jaspers, R.; Lischtschenko, O.; Delabie, E.; Chung, J.

    2010-12-01

    We describe the application of a simple spatial-heterodyne coherence-imaging filter for 2D Doppler imaging of charge exchange recombination (CXR) emission from a heating beam in the TEXTOR tokamak. Results obtained by the CXR imaging system are found to be consistent with measurements obtained using a standard multi-channel spectrometer-based system. We describe the system, indicate possible enhancements and future applications for imaging CXRS.

  19. Plasma ion temperature measurements via charge exchange recombination radiation

    NASA Astrophysics Data System (ADS)

    Fonck, R. J.; Goldston, R. J.; Kaita, R.; Post, D. E.

    1983-02-01

    Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He+ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

  20. Plasma ion temperature measurements via charge-exchange recombination radiation

    SciTech Connect

    Fonck, R.J.; Goldston, R.J.; Kaita, R.; Post, D.E.

    1982-11-01

    Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He/sup +/ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

  1. Plasma ion temperature measurements via charge exchange recombination radiation

    SciTech Connect

    Fonck, R.J.; Goldston, R.J.; Kaita, R.; Post, D.E.

    1983-02-01

    Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler-broadened line profiles of transitions excited by charge-exchange recombination reactions between fast hydrogen atoms and fully ionized low-Z ions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He/sup +/ radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

  2. Energetic Neutral Atom Production due to Charge Exchange at Mars

    NASA Astrophysics Data System (ADS)

    Friedrich, Erena

    2008-05-01

    An energetic neutral atom (ENA) is formed in a charge exchange process where an energetic ion picks up an electron from a neutral particle. Mars, having no notable global intrinsic magnetic field, cannot shield the neutral particles in its atmosphere from the flow of energetic solar wind protons. Consequently, an extensive production of energetic hydrogen atoms (H-ENAs) occurs. In this study a 3D hybrid (kinetic ions, fluid electrons) quasi-neutral particle-in-cell (PIC) plasma simulation is being developed to investigate the production of H-ENAs due to collisions with atomic oxygen (O) and neutral nitrogen molecules (N2) in the transition region of the Martian near-space environment. In order to better study the interaction between Mars' exosphere and ionosphere, multi-species reactions such as ionization by photons, electron recombination and charge exchange are self-consisitently included in the simulation model. The major ions included are exospheric solar wind protons and the planetary O2^+, CO2^+, O^+, and N2^+ ions. The motion of the precipitating particles in the atmosphere is followed, and collisions with atmospheric ions and neutrals (O, CO2, N2) are governed by a Monte Carlo ``collision-by-collision'' algorithm. What is presented is a ``work in progress'' as we work towards our goal of computing the flux of escaping H-ENAs due to charge exchange with O and N2.

  3. Systematics of heavy-ion charge-exchange straggling

    NASA Astrophysics Data System (ADS)

    Sigmund, P.; Schinner, A.

    2016-10-01

    The dependence of heavy-ion charge-exchange straggling on the beam energy has been studied theoretically for several ion-target combinations. Our previous work addressed ions up to krypton, while the present study focuses on heavier ions, especially uranium. Particular attention has been paid to a multiple-peak structure which has been predicted theoretically in our previous work. For high-Z1 and high-Z2 systems, exemplified by U in Au, we identify three maxima in the energy dependence of charge-exchange straggling, while the overall magnitude is comparable with that of collisional straggling. Conversely, for U in C, charge-exchange straggling dominates, but only two peaks lie in the energy range where we presently are able to produce credible predictions. For U-Al we find good agreement with experiment in the energy range around the high-energy maximum. The position of the high-energy peak - which is related to processes in the projectile K shell - is found to scale as Z12 , in contrast to the semi-empirical Z13/2 dependence proposed by Yang et al. Measurements for heavy ions in heavy targets are suggested in order to reconcile a major discrepancy between the present calculations and the frequently-used formula by Yang et al.

  4. Solar System X-rays from Charge Exchange Processes

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.; Christian, D. J.; Bhardwaj, A.; Dennerl, K.; Wolk, S. J.; Bodewits, D.; Combi, M. R.; Zurbuchen, T. H.; Lepri, S. T.

    2013-04-01

    The discovery of high energy x-ray emission in 1996 from comet C/1996 B2 (Hyakutake) uncovered a new class of x-ray emitting objects. Subsequent detections of the morphology, spectra, and time dependence of the x-rays from more than 20 comets have shown that the very soft (E < 1 keV) emission is due to a charge-exchange interaction between highly charged solar wind minor ions and the comet's extended neutral atmosphere. Many solar system objects are now known to shine in the X-ray, including Venus, Mars, the Moon, the Earth, Jupiter, and Saturn, with total power outputs on the MW - GW scale. Like comets, the X-ray emission from the Earth's geo-corona, the Jovian & Saturnian aurorae, and the Martian halo are thought to be driven by charge exchange between highly charged minor (heavy) ions in the solar wind and gaseous neutral species in the bodies' atmosphere. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, and those from disks of Mars, Venus, and the Moon are produced by scattering of solar X-rays. The first soft X-ray observations of Earth’s aurora by Chandra shows that it is highly variable, and the giant planet aurorae are fascinating puzzles that are just beginning to yield their secrets and may be the only x-ray sources not driven directly by the Sun in the whole system as well as properties of hot exo-solar Jupiters. Observations of local solar system charge exchange processes can also help inform us about x-rays produced at more distant hot ionized gas/cold neutral gas interfaces, like the heliopause, stellar astrospheres, galactic star forming regions, and starburst galaxies.

  5. Charge exchange in fluid description of partially ionized plasmas

    NASA Astrophysics Data System (ADS)

    Vranjes, J.; Kono, M.; Luna, M.

    2016-02-01

    The effects of charge exchange on waves propagating in weakly ionized plasmas are discussed. It is shown that for low-frequency processes, ions and neutrals should be treated as a single fluid with some effective charge on all of them. We have derived a new momentum equation which should be used in such an environment. As a result, the low-frequency magnetic waves can propagate even if particles are not magnetized, which is entirely due to the charge exchange and the fact that it is not possible to separate particles into two different populations as charged and neutral species. So there can be no friction force between ions and neutrals in the usual sense. The mean force per particle is proportional to the ionization ratio ni/(ni + nn). Regarding the application of the theory to the Alfvén wave propagation in the lower solar atmosphere, the results predict that the plane of displacement of the fluid must change by 90 deg when an Alfvén wave propagates from the area where particles are un-magnetized (photosphere) to the area where they are magnetized (chromosphere). Because of the most accurate cross-sections which we have here, it is possible to very accurately determine altitudes at which such rotation of the Alfvén wave takes place.

  6. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behavior

    SciTech Connect

    Clary, R.; Smirnov, A.; Dettrick, S.; Knapp, K.; Korepanov, S.; Ruskov, E.; Heidbrink, W. W.; Zhu, Y.

    2012-10-15

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses.

  7. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behaviora)

    NASA Astrophysics Data System (ADS)

    Clary, R.; Smirnov, A.; Dettrick, S.; Knapp, K.; Korepanov, S.; Ruskov, E.; Heidbrink, W. W.; Zhu, Y.

    2012-10-01

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses.

  8. A photodiode-based neutral particle bolometer for characterizing charge-exchanged fast-ion behavior.

    PubMed

    Clary, R; Smirnov, A; Dettrick, S; Knapp, K; Korepanov, S; Ruskov, E; Heidbrink, W W; Zhu, Y

    2012-10-01

    A neutral particle bolometer (NPB) has been designed and implemented on Tri Alpha Energy's C-2 device in order to spatially and temporally resolve the charge-exchange losses of fast-ion populations originating from neutral beam injection into field-reversed configuration plasmas. This instrument employs a silicon photodiode as the detection device with an integrated tungsten filter coating to reduce sensitivity to light radiation. Here we discuss the technical aspects and calibration of the NPB, and report typical NPB measurement results of wall recycling effects on fast-ion losses.

  9. Charge state dependence of channeled ion energy loss

    NASA Astrophysics Data System (ADS)

    Golovchenko, J. A.; Goland, A. N.; Rosner, J. S.; Thorn, C. E.; Wegner, H. E.; Knudsen, H.; Moak, C. D.

    1981-02-01

    The charge state dependence of channeled ion energy loss has been determined for a series of ions ranging from fluorine to chlorine along the <110> direction in a silicon crystal. Energy losses for both bare ions and ions partially clothed with bound electrons at EA≅3 MeV/amu have been measured. The energy-loss rate for bare ions follows a strict Z21 scaling and agrees reasonably well with quantal perturbation calculations without the need for polarization or Bloch corrections. An explanation for this result is discussed. The clothed-ion energy losses appear to demonstrate screening effects that agree qualitatively with simple estimates. The angular dependence of the observed energy-loss effects is also presented.

  10. Exciton transport, charge extraction, and loss mechanisms in organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Scully, Shawn Ryan

    the primary losses that puts stringent requirements on the charge carrier mobilities in these cells is the recombination losses due to space charge build up at the heterojunction. Because electrons are confined to the acceptor and holes to the donor, net charge density always exists even when mobilities are matched, in contrast to bulk heterojunctions wherein matched mobilities lead to zero net charge. This net charge creates an electric field which opposes the built-in field and limits the current that can be carried away from this heterojunction. Using simulations we show that for relevant current densities charge carrier mobilities must be higher than 10-4 cm2/V.s to avoid significant losses due to space charge formation. In the last part of this work, we will focus on the second class of architectures in which exciton harvesting is efficient. We will present a systematic analysis of one of the leading polymer:fullerene bulk heterojunction cells to show that losses in this architecture are due to charge recombination. Using optical measurements and simulations, exciton harvesting measurements, and device characteristics we will show that the dominant loss is likely due to field-dependent geminate recombination of the electron and hole pair created immediately following exciton dissociation. No losses in this system are seen due to bimolecular recombination or space charge which provides information on charge-carrier mobility targets necessary for the future design of high efficiency organic photovoltaics.

  11. Observations of solar wind ion charge exchange in the comet Halley coma

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Shelley, E. G.; Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Ip, W.-H.; Balsiger, H.; Reme, H.

    1991-01-01

    Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of comet Halley. As the comet was approached, the He(++) to proton density ratio increased until about 1 hour before closest approach after which time it decreased. Abrupt increases in this ratio were also observed in the beginning and near the end of the so-called Mystery Region (8.6 - 5.5(10)(exp 5) km from the comet along the spacecraft trajectory). These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He(++) to proton density ratio is quantitatively consistent with a combination of the addition of protons of cometary origin to the plasma and loss of plasma through charge exchange of protons and He(++). In general agreement with the solar wind proton and He(++) observations, solar wind oxygen and carbon ions were observed to charge exchange from higher to lower charge states with decreasing distance to the comet. The more abrupt increases in the He(++) to proton and the He(++) to O(6+) density ratios in the mystery region require a change in the solar wind ion composition in this region while the correlation with energetic electrons indicates processes associated with the comet.

  12. Charge-Exchange Processes of Titanium-Doped Aluminate Crystals

    NASA Astrophysics Data System (ADS)

    Wong, Wing Cheong

    1995-01-01

    Titanium exists in more than one charge state in the aluminate crystals: it is stable as Ti^ {3+} and Ti^{4+}. Other than the intense Ti^{4+ } absorption, a ubiquitous absorption/luminescence excitation band in the UV region is identified as a titanium -bound exciton in Al_2rm O_3, Y_3Al_5rm O_{12}, {rm YAlO}_3, MgAl_2O _4, and LaMgAl_{11} {rm O}_{19}. One -step and two-step photoconductivities of Ti^ {3+} are measured and compared. While the selectivity of the two-step process is demonstrated, its use in locating the energy threshold is hampered by the small Franck-Condon factor for the transition between the Ti^{3+} ^2{ rm E} excited state and Ti^ {4+}. The titanium-bound exciton band, together with the one-step photocurrent signal, makes it possible to determine the photoionization energy threshold accurately. The charge-transfer transition energy thresholds of Ti^{4+} are obtained from the emission and the luminescence excitation spectra. Locally and non-locally charge compensated Ti^{4+ } are found in Al_2{rm O}_3. The luminescence kinetics for the two kinds of Ti^{4+} are well explained by a three-level system with a lower triplet excited state and a higher singlet excited state. These charge-exchange threshold energies can be deduced from the Born-Haber thermodynamical cycle. The electrostatic site potentials are calculated and from it, the calculated photoionization and charge-transfer energy thresholds are found to be consistent with the experimental results. The deficiency of this model is pointed out and possible improvement is discussed. Quantitatively, the sum of the two charge-exchange energy thresholds is close to the band-gap energy of the host crystal. This offers a convenient way for material characterization. Provided that any two of the three quantities (band-gap energy, photoionization energy threshold, and charge-transfer transition energy threshold) have been found, the third quantity can be calculated. In addition, the trapping of charge

  13. Pion double charge exchange in a composite-meson model

    SciTech Connect

    Kezerashvili, R. Ya.; Boyko, V. S.

    2007-01-15

    The pion double charge exchange amplitude is evaluated in a composite-meson model based on the four-quark interaction. The model assumes that the mesons are two-quark systems and can interact with each other only through quark loops. To evaluate the meson exchange current contribution, the form factors of the two-pion decay modes of the {rho},{sigma}, and f{sub 0} mesons have been used in the calculations. The contribution of the four-quark box diagram has been taken into account as well as a contact diagram. The contributions of the {rho},{sigma}, and f{sub 0} mesons increase the forward scattering cross section, which depends weakly on the energy.

  14. Charge exchange of low-energy ions in thin carbon foils

    NASA Technical Reports Server (NTRS)

    Buergi, Alfred; Oetliker, Michael; Bochsler, Peter; Geiss, Johannes; Coplan, Michael A.

    1990-01-01

    In order to calibrate a time-of-flight mass spectrometer which is to be flown in the solar wind, the charge exchange properties of low-energy ions in thin carbon foils have been investigated. Incident ions of He, C, N, O, Ne, and Ar with energies in the range 0.5-2 keV/nucleon have been used to measure charge-state distribution, residual energy, and angular distribution after transmission through thin (1-6 microgram/sq cm) carbon foils. Within such foils, an equilibrium between ionization and recombination of the projectile is rapidly established, and, consequently, the charge state of the emerging particle depends essentially on its residual velocity. A comparison of the charge exchange properties of Ne-22 with Ne-20 demonstrates that indeed the velocity (and not the energy) of the emerging particle determines its final charge. A comparison of properties of different elements provides an indication of an electron shell effect. Predictions for the energy loss of ions within the carbon foils made with the TRIM code are in good agreement with the experimental results presented in this paper.

  15. (p,n) Charge-Exchange Reactions in Inverse Kinematics

    NASA Astrophysics Data System (ADS)

    Lipschutz, Samuel; NSCL E10003 Collaboration

    2014-09-01

    Charge-exchange experiments at intermediate energy yield important information about collective excitations with spin-isospin degrees of freedom. The properties of isovector giant resonances in neutron-rich rare-isotopes provide stringent tests of theoretical models and are important inputs for modeling of astrophysical phenomena. The (p,n) charge-exchange reaction in inverse kinematics has been developed as a new tool for investigating isovector giant resonances in rare isotopes. The technique, which involves the detection of low-energy neutrons that recoil from a hydrogen target, while detecting fast beam-like ejectiles in a magnetic spectrometer, was successfully employed at NSCL to study the 56Ni(p,n) reaction. Continuing with this technique a 16C(p,n) experiment at 100 MeV/u aimed at extracting isovector multipole strengths up to excitation energies of 30 MeV was preformed. The Low Energy Neutron Detector Array (LENDA) and the Versatile Array of Neutron Detectors at Low Energy (VANDLE) were utilized in combination with the Ursinus Liquid Hydrogen Target and the S800 spectrometer to perform this experiment. Preliminary results will be shown. Charge-exchange experiments at intermediate energy yield important information about collective excitations with spin-isospin degrees of freedom. The properties of isovector giant resonances in neutron-rich rare-isotopes provide stringent tests of theoretical models and are important inputs for modeling of astrophysical phenomena. The (p,n) charge-exchange reaction in inverse kinematics has been developed as a new tool for investigating isovector giant resonances in rare isotopes. The technique, which involves the detection of low-energy neutrons that recoil from a hydrogen target, while detecting fast beam-like ejectiles in a magnetic spectrometer, was successfully employed at NSCL to study the 56Ni(p,n) reaction. Continuing with this technique a 16C(p,n) experiment at 100 MeV/u aimed at extracting isovector multipole

  16. Charge exchange reactions and solar neutrino detection in 81Br

    NASA Astrophysics Data System (ADS)

    Liu, K. F.; Gabbard, F.

    1983-01-01

    The feasibility of 81Br as the detector of the solar neutrino flux hinges upon the knowledge of the Gamow-Teller matrix element from the ground state of 81Br to the 52- state at 0.457 MeV in 81Kr. The possibility of obtaining this matrix element is discussed in terms of the (p, n) and (3He, t) charge exchange reactions. NUCLEAR REACTIONS 81Br(p, n)81Kr and 81Br(3He, t)81Kr Gamow-Teller transitions; solar neutrino detection.

  17. USING KAPPA FUNCTIONS TO CHARACTERIZE OUTER HELIOSPHERE PROTON DISTRIBUTIONS IN THE PRESENCE OF CHARGE-EXCHANGE

    SciTech Connect

    Zirnstein, E. J.; McComas, D. J. E-mail: dmccomas@swri.edu

    2015-12-10

    Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.

  18. Using Kappa Functions to Characterize Outer Heliosphere Proton Distributions in the Presence of Charge-exchange

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; McComas, D. J.

    2015-12-01

    Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.

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

    SciTech Connect

    Beiersdorfer, P.; Kaita, R.; Goldston, R.J.

    1984-01-01

    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 approx. = R/sub 0/ + a indicate the presence of a non-..mu..-conserving acceleration mechanism.

  20. Kinetic theory for charge-exchange spectroscopy: Effects of magnetic and electric fields on the distribution function after charge-exchange

    SciTech Connect

    Burrell, K. H.; Munoz Burgos, J. M.

    2012-07-15

    In plasmas equipped with neutral beam injection, excitation of atomic spectral lines via charge-exchange with neutral atoms is the basis of one of the standard plasma diagnostic techniques for ion density, temperature, and velocity. In order to properly interpret the spectroscopic results, one must consider the effects of the energy dependence of the charge-exchange cross-section as well as the motion of the ion after charge-exchange during the period when it is still in the excited state. This motion is affected by the electric and magnetic fields in the plasma. The present paper gives results for the velocity distribution function of the excited state ions and considers in detail the cross-section and ion motion effects on the post charge-exchange velocity. The expression for this velocity in terms of the charge-exchange cross-section and the pre charge-exchange velocity allows that latter velocity to be determined. The present paper is the first to consider the effect of the electric as well as the magnetic field and demonstrates that electric field and diamagnetic terms appear in the expression for the inferred velocity. The present formulation also leads to a novel technique for assessing the effect of the energy dependence of the charge-exchange cross-section on the inferred ion temperature.

  1. Energy straggling of low-energy ion beam in a charge exchange cell for negative ion production

    SciTech Connect

    Takeuchi, S.; Sasao, M.; Sugawara, H.; Tanaka, N.; Kisaki, M.; Okamoto, A.; Shinto, K.; Kitajima, S.; Nishiura, M.; Wada, M.

    2008-02-15

    Energy straggling in a charge exchange cell, which is frequently used for negative ion production, was studied experimentally and compared with the results of theoretical evaluation. The change of the energy spectrum of a He{sup +} beam due to charge exchange processes in argon gas was measured in the energy range of 2-6 keV. Energy straggling by multiple collisions is expressed by the energy loss formula due to inelastic and elastic processes. The impact parameter is related to the elastic scattering angle, and the geometry of the charge exchange cell and other components of the beam transportation system determines the maximum acceptable scattering angle. The energy spread was evaluated taking the integral limit over the impact parameter into consideration. The theoretical results showed good agreement with those of actual measurement.

  2. Charge-exchange reactions with a radioactive triton beam

    SciTech Connect

    Jaenecke, J.

    1998-12-21

    A high-resolution (t, {sup 3}He) test experiment has been performed recently by making use of a secondary triton beam produced by fragmentation of {alpha}-particles. The purpose of this charge-exchange experiment was to achieve good energy resolution in an (n,p)-type reaction at intermediate bombarding energies. The experiment was carried out with the K1200 cyclotron at the National Superconducting Cyclotron Laboratory using the A1200 beam-analysis system and the S800 magnetic spectrometer. The beam-analysis system was used to transport the energy-dispersed radioactive triton beam from the production target to the target position, and the magnetic spectrometer was used to focus the dispersion-matched {sup 3}He particles from the (t, {sup 3}He) reaction at 0 degree sign onto the focal plane of the spectrometer. An energy resolution of 200-250 keV was achieved.

  3. Improved edge charge exchange recombination spectroscopy in DIII-D

    NASA Astrophysics Data System (ADS)

    Chrystal, C.; Burrell, K. H.; Grierson, B. A.; Haskey, S. R.; Groebner, R. J.; Kaplan, D. H.; Briesemeister, A.

    2016-11-01

    The charge exchange recombination spectroscopy diagnostic on the DIII-D tokamak has been upgraded with the addition of more high radial resolution view chords near the edge of the plasma (r/a > 0.8). The additional views are diagnosed with the same number of spectrometers by placing fiber optics side-by-side at the spectrometer entrance with a precise separation that avoids wavelength shifted crosstalk without the use of bandpass filters. The new views improve measurement of edge impurity parameters in steep gradient, H-mode plasmas with many different shapes. The number of edge view chords with 8 mm radial separation has increased from 16 to 38. New fused silica fibers have improved light throughput and clarify the observation of non-Gaussian spectra that suggest the ion distribution function can be non-Maxwellian in low collisionality plasmas.

  4. Improved edge charge exchange recombination spectroscopy in DIII-D

    DOE PAGES

    Chrystal, Colin; Burrell, K. H.; Grierson, Brian A.; Haskey, Shaun R.; Groebner, R. J.; Kaplan, David H.; Briesemeister, Alexis R.

    2016-08-02

    The charge exchange recombination spectroscopy diagnostic on the DIII-D tokamak has been upgraded with the addition of more high radial resolution view chords near the edge of the plasma (r/a > 0.8). The additional views are diagnosed with the same number of spectrometers by placing fiber optics side-by-side at the spectrometer entrance with a precise separation that avoids wavelength shifted crosstalk without the use of bandpass filters. The new views improve measurement of edge impurity parameters in steep gradient, H-mode plasmas with many different shapes. The number of edge view chords with 8 mm radial separation has increased from 16more » to 38.As a result, new fused silica fibers have improved light throughput and clarify the observation of non-Gaussian spectra that suggest the ion distribution function can be non-Maxwellian in low collisionality plasmas.« less

  5. Extraction of Poloidal Velocity from Charge Exchange Recombination Spectroscopy Measurements

    SciTech Connect

    W.M. Solomon; K.H. Burrell; P. Gohil; R.J. Groebner; L.R. Baylor

    2004-07-16

    A novel approach has been implemented on DIII-D to allow the correct determination of the plasma poloidal velocity from charge exchange spectroscopy measurements. Unlike usual techniques, the need for detailed atomic physics calculations to properly interpret the results is alleviated. Instead, the needed atomic physics corrections are self-consistently determined directly from the measurements, by making use of specially chosen viewing chords. Modeling results are presented that were used to determine a set of views capable of measuring the correction terms. We present the analysis of a quiescent H-mode discharge, illustrating that significant modifications to the velocity profiles are required in these high ion temperature conditions. We also present preliminary measurements providing the first direct comparison of the standard cross-section correction to the atomic physics calculations.

  6. Influence of charge exchange on the collection of the laser produced ions

    NASA Astrophysics Data System (ADS)

    Hasegawa, Shuichi; Takei, Manabu; Suzuki, Atsuyuki; Kurosawa, Hitoshi

    2001-12-01

    We evaluated influences of charge exchange on ion collection of laser isotope separation of uranium. We made a two-dimensional code based on fluid dynamics taking the charge exchange term into consideration. Parametric study was performed in terms of electric amplitude, ion density, and electron temperature. In addition to parallel electrode arrangement, calculations were performed for Π- and M-type arrangements. The ratio of charge exchanged ions is found to largely depend on the collection time.

  7. High-throughput charge exchange recombination spectroscopy system on MAST

    SciTech Connect

    Conway, N. J.; Carolan, P. G.; McCone, J.; Walsh, M. J.; Wisse, M.

    2006-10-15

    A major upgrade to the charge exchange recombination spectroscopy system on MAST has recently been implemented. The new system consists of a high-throughput spectrometer coupled to a total of 224 spatial channels, including toroidal and poloidal views of both neutral heating beams on MAST. Radial resolution is {approx}1 cm, comparable to the ion Larmor radius. The toroidal views are configured with 64 channels per beam, while the poloidal views have 32 channels per beam. Background channels for both poloidal and toroidal views are also provided. A large transmission grating is at the heart of the new spectrometer, with high quality single lens reflex lenses providing excellent imaging performance and permitting the full exploitation of the available etendue of the camera sensor. The charge-coupled device camera chosen has four-tap readout at a maximum aggregate speed of 8.8 MHz, and it is capable of reading out the full set of 224 channels in less than 4 ms. The system normally operates at 529 nm, viewing the C{sup 5+} emission line, but can operate at any wavelength in the range of 400-700 nm. Results from operating the system on MAST are shown, including impurity ion temperature and velocity profiles. The system's excellent spatial resolution is ideal for the study of transport barrier phenomena on MAST, an activity which has already been advanced significantly by data from the new diagnostic.

  8. Energy loss of a heavy particle near 3D charged rotating hairy black hole

    NASA Astrophysics Data System (ADS)

    Naji, Jalil

    2014-01-01

    In this paper we consider a charged rotating black hole in three dimensions with a scalar charge and discuss the energy loss of a heavy particle moving near the black-hole horizon. We also study quasi-normal modes and find the dispersion relations. We find that the effect of scalar charge and electric charge increases the energy loss.

  9. Cometary X-Rays: Line Emission Cross Sections for Multiply Charged Solar Wind Ion Charge Exchange

    SciTech Connect

    Otranto, S; Olson, R E; Beiersdorfer, P

    2006-12-22

    Absolute line emission cross sections are presented for 1 keV/amu charge exchange collisions of multiply charged solar wind ions with H{sub 2}O, H, O, CO{sub 2}, and CO cometary targets. The present calculations are contrasted with available laboratory data. A parameter-free model is used to successfully predict the recently observed x-ray spectra of comet C/LINEAR 1999 S4. We show that the resulting spectrum is extremely sensitive to the time variations of the solar wind composition. Our results suggest that orbiting x-ray satellites may be a viable way to predict the solar wind intensities and composition on the Earth many hours before the ions reach the earth.

  10. Solar Wind Charge Exchange Studies Of Highly Charged Ions On Atomic Hydrogen

    SciTech Connect

    Draganic, I. N.; Havener, C. C.; Seely, D. G.; McCammon, D.

    2011-06-01

    Accurate studies of low-energy charge exchange (CX) are critical to understanding underlying soft X-ray radiation processes in the interaction of highly charged ions from the solar wind with the neutral atoms and molecules in the heliosphere, cometary comas, planetary atmospheres, interstellar winds, etc.. Particularly important are the CX cross sections for bare, H-like, and He-like ions of C, N, O and Ne, which are the dominant charge states for these heavier elements in the solar wind. Absolute total cross sections for single electron capture by H-like ions of C, N, O and fully-stripped O ions from atomic hydrogen have been measured in an expanded range of relative collision energies (5 eV/u-20 keV/u) and compared to previous H-oven measurements. The present measurements are performed using a merged-beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source installed on a high voltage platform at the Oak Ridge National Laboratory. For the collision energy range of 0.3 keV/u-3.3 keV/u, which corresponds to typical ion velocities in the solar wind, the new measurements are in good agreement with previous H-oven measurements. The experimental results are discussed in detail and compared with theoretical calculations where available.

  11. Solar Wind Charge Exchange Studies of Highly Charged Ions on Atomic Hydrogen

    SciTech Connect

    Draganic, Ilija N; Seely, D. G.; McCammon, D; Havener, Charles C

    2011-01-01

    Accurate studies of low energy charge exchange (CX) are critical to understanding underlying soft X ray radiation processes in the interaction of highly charged ions from the solar wind with the neutral atoms and molecules in the heliosphere, cometary comas, planetary atmospheres, interstellar winds, etc.. Particularly important are the CX cross sections for bare, H like, and He like ions of C, N, O and Ne, which are the dominant charge states for these heavier elements in the solar wind. Absolute total cross sections for single electron capture by H like ions of C, N, O and fully stripped O ions from atomic hydrogen have been measured in an expanded range of relative collision energies (5 eV u 20 keV u) and compared to previous H oven measurements. The present measurements are performed using a merged beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source installed on a high voltage platform at the Oak Ridge National Laboratory. For the collision energy range of 0.3 keV u 3.3 keV u, which corresponds to typical ion velocities in the solar wind, the new measurements are in good agreement with previous H oven measurements. The experimental results are discussed in detail and compared with theoretical calculations where available.

  12. Charge Sharing and Charge Loss in a Cadmium-Zinc-Telluride Fine-Pixel Detector Array

    NASA Technical Reports Server (NTRS)

    Gaskin, J. A.; Sharma, D. P.; Ramsey, B. D.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Because of its high atomic number, room temperature operation, low noise, and high spatial resolution a Cadmium-Zinc-Telluride (CZT) multi-pixel detector is ideal for hard x-ray astrophysical observation. As part of on-going research at MSFC (Marshall Space Flight Center) to develop multi-pixel CdZnTe detectors for this purpose, we have measured charge sharing and charge loss for a 4x4 (750micron pitch), lmm thick pixel array and modeled these results using a Monte-Carlo simulation. This model was then used to predict the amount of charge sharing for a much finer pixel array (with a 300micron pitch). Future work will enable us to compare the simulated results for the finer array to measured values.

  13. Charge Exchange Contribution to the Decay of the Ring Current, Measured by Energetic Neutral Atoms (ENAs)

    NASA Technical Reports Server (NTRS)

    Jorgensen, A. M.; Henderson, M. G.; Roelof, E. C.; Reeves, G. D.; Spence, H. E.

    2001-01-01

    In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases.

  14. More Than Charged Base Loss — Revisiting the Fragmentation of Highly Charged Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Nyakas, Adrien; Eberle, Rahel P.; Stucki, Silvan R.; Schürch, Stefan

    2014-07-01

    Tandem mass spectrometry is a well-established analytical tool for rapid and reliable characterization of oligonucleotides (ONs) and their gas-phase dissociation channels. The fragmentation mechanisms of native and modified nucleic acids upon different mass spectrometric activation techniques have been studied extensively, resulting in a comprehensive catalogue of backbone fragments. In this study, the fragmentation behavior of highly charged oligodeoxynucleotides (ODNs) comprising up to 15 nucleobases was investigated. It was found that ODNs exhibiting a charge level (ratio of the actual to the total possible charge) of 100% follow significantly altered dissociation pathways compared with low or medium charge levels if a terminal pyrimidine base (3' or 5') is present. The corresponding product ion spectra gave evidence for the extensive loss of a cyanate anion (NCO-), which frequently coincided with the abstraction of water from the 3'- and 5'-end in the presence of a 3'- and 5'-terminal pyrimidine nucleobase, respectively. Subsequent fragmentation of the M-NCO- ion by MS3 revealed a so far unreported consecutive excision of a metaphosphate (PO3 -)-ion for the investigated sequences. Introduction of a phosphorothioate group allowed pinpointing of PO3 - loss to the ultimate phosphate group. Several dissociation mechanisms for the release of NCO- and a metaphosphate ion were proposed and the validity of each mechanism was evaluated by the analysis of backbone- or sugar-modified ONs.

  15. Electron-exchange effects on the charge capture process in degenerate quantum plasmas

    SciTech Connect

    Jung, Young-Dae; Akbari-Moghanjoughi, M.

    2014-03-15

    The electron-exchange effects on the charge capture process are investigated in degenerate quantum plasmas. The Bohr-Lindhard formalism with the effective interaction potential is employed to obtain the charge capture radius, capture probability, and capture cross section as functions of the impact parameter, projectile energy, electron-exchange parameter, Fermi energy, and plasmon energy. The result shows that the electron-exchange effect enhances the charge capture radius and the charge capture cross section in semiconductor quantum plasmas. It is also found that the charge capture radius and charge capture cross section increases with an increase of the Fermi energy and, however, decreases with increasing plasmon energy. Additionally, it is found that the peak position of the charge capture cross section is receded from the collision center with an increase of the electron-exchange parameter.

  16. Charge-exchange reaction by Reggeon exchange and W{sup +}W{sup −}-fusion

    SciTech Connect

    Schicker, R.

    2015-04-10

    Charge-exchange reactions at high energies are examined. The existing cross section data on the Reggeon induced reaction pp → n + Δ{sup ++} taken at the ZGS and ISR accelerators are extrapolated to the energies of the RHIC and LHC colliders. The interest in the charge-exchange reaction induced by W{sup ±}-fusion is presented, and the corresponding QCD-background is examined.

  17. XMM-Newton Observations of Solar Wind Charge Exchange Emission

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Collier, M. R.; Kuntz, K. D.

    2004-01-01

    We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by O VII and O VIII lines at 0.57 keV and 0.65 keV, O VIII (and possibly Fe XVII) lines at approximately 0.8 keV, Ne IX lines at approximately 0.92 keV, and Mg XI lines at approximately 1.35 keV. This spectrum is consistent with what is expected from charge exchange emission between the highly ionized solar wind and either interstellar neutrals in the heliosphere or material from Earth's exosphere. The emission is clearly seen as a low-energy ( E less than 1.5 keV) spectral enhancement in one of a series of observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by the ACE satellite. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has ion ratios with significantly enhanced higher ionization states. Whereas observations of the solar wind plasma made at a single point reflect only local conditions which may only be representative of solar wind properties with spatial scales ranging from less than half of an Earth radii (approximately 10 s) to 100 Earth radii, X-ray observations of solar wind charge exchange are remote sensing measurements which may provide observations which are significantly more global in character. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of more cosmological objects. It can provide emission lines at zero redshift which are of particular interest (e.g., O VII and O VIII) in studies of diffuse thermal emission, and which can therefore act as contamination in objects which cover the entire detector field of view. We propose the use of solar wind monitoring data, such as from the ACE and Wind spacecraft, as a diagnostic to screen for such possibilities.

  18. Charge exchange of solar wind ions in the Comet Halley coma

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Ing-H. afgoldstein, B. E. AGGOLDSTEIN, R.; Ing-H. afgoldstein, B. E. AGGOLDSTEIN, R.

    1986-01-01

    The He(2+) and He(+) radial profiles measured by the Giotto mass spectrometer on the inbound trajectory to comet Halley are compared to a simple 1-dimensional charge exchange model. Results indicate that charge exchange alone cannot account for the observed radial profiles of He(2+) and He(+).

  19. Spin-Isospin responses via charge exchange reactions of RI beams at SHARAQ

    SciTech Connect

    Shimoura, Susumu

    2012-11-12

    Nuclear spectroscopy via direct reactions of RI beams is discussed focusing on characteristics of charge-exchange reactions of RI beams. Recent experiments using the SHARAQ spectrometer at the RIBF are presented, where isovector spin monopole and spin-non-flip monopole responses are studied by charge exchange reaction of RI beams. Some experimental plans and perspectives are also presented.

  20. Charge Exchange, from the Laboratory to Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Betancourt-Martinez, Gabriele; Beiersdorfer, Peter; Brown, Gregory; Hell, Natalie; Leutenegger, Maurice A.; Porter, Frederick S.; Reynolds, Christopher S.

    2016-04-01

    X-ray emission due to charge exchange (CX) between solar wind ions and neutrals in comets and planetary atmospheres is ubiquitous in the solar system, and is also a significant foreground in all observations from low-Earth orbit. It is also possible that CX is common astrophysically, in any environment where hot plasma and cold gas interact. A current challenge is that theoretical models of CX spectra do not always accurately describe observations, and require further experimental verification. This is especially important to focus on now, as the recent launch of Astro-H is providing us with the first high-resolution spectra of extended x-ray sources. In order to improve our understanding and modeling of CX spectra, we take advantage of the laboratory astrophysics program at the Lawrence Livermore National Laboratory and use an Electron Beam Ion Trap (EBIT) to perform CX experiments, using the EBIT Calorimeter Spectrometer. We present experimental benchmarks that can be used to develop a more comprehensive and accurate CX theory. On the observational side, we also investigate the possibility of CX occurring in the filaments around the central galaxy of the Perseus cluster, NGC 1275. We use Chandra ACIS data, combined with what we know about laboratory CX spectra, to investigate the possibility of CX being a significant contributor to the x-ray emission.

  1. Charge exchange spectroscopy as a fast ion diagnostic on TEXTORa)

    NASA Astrophysics Data System (ADS)

    Delabie, E.; Jaspers, R. J. E.; von Hellermann, M. G.; Nielsen, S. K.; Marchuk, O.

    2008-10-01

    An upgraded charge exchange spectroscopy diagnostic has been taken into operation at the TEXTOR tokamak. The angles of the viewing lines with the toroidal magnetic field are close to the pitch angles at birth of fast ions injected by one of the neutral beam injectors. Using another neutral beam for active spectroscopy, injected counter the direction in which fast ions injected by the first beam are circulating, we can simultaneously measure a fast ion tail on the blue wing of the Dα spectrum while the beam emission spectrum is Doppler shifted to the red wing. An analysis combining the two parts of the spectrum offers possibilities to improve the accuracy of the absolute (fast) ion density profiles. Fast beam modulation or passive viewing lines cannot be used for background subtraction on this diagnostic setup and therefore the background has to be modeled and fitted to the data together with a spectral model for the slowing down feature. The analysis of the fast ion Dα spectrum obtained with the new diagnostic is discussed.

  2. Charge exchange recombination spectroscopy on the T-10 tokamak.

    PubMed

    Klyuchnikov, L A; Krupin, V A; Nurgaliev, M R; Korobov, K V; Nemets, A R; Dnestrovskij, A Yu; Tugarinov, S N; Serov, S V; Naumenko, N N

    2016-05-01

    The charge exchange recombination spectroscopy (CXRS) diagnostics on the T-10 tokamak is described. The system is based on a diagnostic neutral beam and includes three high etendue spectrometers designed for the ITER edge CXRS system. A combined two-channel spectrometer is developed for simultaneous measurements of two beam-induced spectral lines using the same lines of sight. A basic element of the combined spectrometer is a transmitting holographic grating designed for the narrow spectral region 5291 ± 100 Å. The whole CXRS system provides simultaneous measurements of two CXRS impurity spectra and Hα beam line. Ion temperature measurements are routinely provided using the C(6+) CXRS spectral line 5291 Å. Simultaneous measurements of carbon densities and one more impurity (oxygen, helium, lithium etc.) are carried out. Two light collecting systems with 9 lines of sight in each system are used in the diagnostics. Spatial resolution is up to 2.5 cm and temporal resolution of 1 ms is defined by the diagnostic neutral beam diameter and pulse duration, respectively. Experimental results are shown to demonstrate a wide range of the CXRS diagnostic capabilities on T-10 for investigation of impurity transport processes in tokamak plasma. Developed diagnostics provides necessary experimental data for studying of plasma electric fields, heat and particle transport processes, and for investigation of geodesic acoustic modes.

  3. STUDIES OF X-RAY PRODUCTION FOLLOWING CHARGE EXCHANGE RECOMBINATION BETWEEN HIGHLY CHARGED IONS AND NEUTRAL ATOMS AND MOLECULES

    SciTech Connect

    Brown, G V; Beiersdorfer, P; Chen, H; Clementson, J; Frankel, M; Gu, M F; Kelley, R L; Kilbourne, C A; Porter, F S; Thorn, D B; Wargelin, B J

    2008-08-28

    We have used microcalorimeters built by the NASA/Goddard Space Flight Center and the Lawrence Livermore National Laboratory Electron Beam Ion Trap to measure X-ray emission produced by charge exchange reactions between highly charged ions colliding with neutral helium, hydrogen, and nitrogen gas. Our measurements show the spectral dependence on neutral species and also show the distinct differences between spectra produced by charge exchange reactions and those produced by direct impact excitation. These results are part of an ongoing experimental investigation at the LLNL EBIT facility of charge exchange spectral signatures and can be used to interpret X-ray spectra produced by a variety of laboratory and celestial sources including cometary and planetary atmospheres, the Earth's magnetosheath, the heliosphere, and tokamaks.

  4. Excitation and Charge Exchange Phenomena in Astronomical Objects: Measurement of Cross Sections and Lifetimes

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara; Smith, S.; Lozano, J.; Cadez, I.; Greewnood, J.; Mawhovter, R.; Williams, I.; Niimura, M.

    2003-01-01

    This document addresses extreme ultraviolet radiation and X-ray emissions from comets, planets and heliospheric gases focusing on the measurement of charge-exchange cross sections and radiative lifetimes. Highly-charged heavy ions present in the solar wind, and their abundance relative to the total oxygen-ion abundance are detailed. The plan for the Jet Propulsion Laboratory high-charge ion facility is outlined detailing its ability to measure absolute collisional excitation cross sections, absolute charge-exchange cross sections, lifetimes of metastable ion levels, and X-ray emission spectra following charge changes.

  5. Observations of solar wind ion charge exchange in the Comet Halley coma

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Shelley, E. G.; Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Ip, W.-H.; Balsiger, H.; Reme, H.

    1991-01-01

    Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of Comet Halley. As the comet was approached, the He(2+) to proton density ratio increased from 2.5 percent in the solar wind to about 4 percent about 1 hr before closest approach after which time it decreased to about 1 percent. Abrupt increases in this ratio from 2.5 to 4.5 percent were also observed in the beginning and near the end of the so-called Mystery Region. These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He(2+) to proton density ratio is quantitatively consistent with a combination of the addition of protons of Cometary origin to the plasma and loss of plasma through charge exchange of protons and He(2+).

  6. Status of Charge Exchange Cross Section Measurements for Highly Charged Ions on Atomic Hydrogen

    NASA Astrophysics Data System (ADS)

    Draganic, I. N.; Havener, C. C.; Schultz, D. R.; Seely, D. G.; Schultz, P. C.

    2011-05-01

    Total cross sections of charge exchange (CX) for C5+, N6+, and O7+ ions on ground state atomic hydrogen are measured in an extended collision energy range of 1 - 20,000 eV/u. Absolute CX measurements are performed using an improved merged-beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source mounted on a high voltage platform. In order to improve the problematic H+ signal collection for these exoergic CX collisions at low relative energies, a new double focusing electrostatic analyzer was installed. Experimental CX data are in good agreement with all previous H-oven relative measurements at higher collision energies. We compare our results with the most recent molecular orbital close-coupling (MOCC) and atomic orbital close-coupling (AOCC) theoretical calculations. Work supported by the NASA Solar & Heliospheric Physics Program NNH07ZDA001N, the Office of Fusion Energy Sciences and the Division of Chemical Sciences, Geosciences, and Biosciences, and the Office of Basic Energy Sciences of the U.S. DoE.

  7. Highly charged swelling mica-type clays for selective Cu exchange.

    PubMed

    Ravella, Ramesh; Komarneni, Sridhar; Martinez, Carmen Enid

    2008-01-01

    There is a need to develop highly CU2+ selective materials which can potentially remediate copper contaminated soils and water. Here we show that several highly charged synthetic swelling mica-type clays are highly selective for copper exchange. The synthetic micas have cation exchange capacities (CECs), which are close to their theoretical values. Both Na-saturated and Mg-saturated micas were investigated for Cu ion exchange selectivity. Ion exchange isotherms and Kielland plots were constructed using the equilibrated solution analyses. From these studies it was found that Na-4-mica and Na-3-mica could selectively exchange copper at lower concentrations from solution, whereas Na-2-mica sample performed better by showing Cu ion exchange selectively to almost its capacity. The EPR spectra of Cu-exchanged micas coincide with the mica's charge characteristics that predict increased binding strength of exchangeable Cu in Na-4-mica and Na-3-mica than in Na-2-mica. PMID:18350884

  8. Invited Parallel Talk: Forward pion-nucleon charge exchange reaction and Regge constraints

    NASA Astrophysics Data System (ADS)

    Huang, Fei; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meißner, U.-G.

    2009-12-01

    We present our recent study of pion-nucleon charge exchange amplitudes above 2 GeV. We analyze the forward pion-nucleon charge exchange reaction data in a Regge model and compare the resulting amplitudes with those from the Karlsruhe-Helsinki and George-Washington-University partial-wave analyses. We explore possible high-energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV. Our results show that for the pion-nucleon charge exchange reaction, the appropriate energy region for matching meson-nucleon dynamics to diffractive scattering should be around 3 GeV for the helicity flip amplitude.

  9. Carbon charge exchange analysis in the ITER-like wall environment

    SciTech Connect

    Menmuir, S.; Giroud, C.; Hawkes, N. C.; Biewer, T. M.; Coffey, I. H.; Delabie, E.; Sertoli, M.

    2014-11-15

    Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06 nm and demonstrates the need to revise the core charge exchange analysis for this line. An investigation has been made of this spectral region in different plasma conditions and the revised description of the spectral lines to be included in the analysis is presented.

  10. Carbon charge exchange analysis in the ITER-like wall environment.

    PubMed

    Menmuir, S; Giroud, C; Biewer, T M; Coffey, I H; Delabie, E; Hawkes, N C; Sertoli, M

    2014-11-01

    Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06 nm and demonstrates the need to revise the core charge exchange analysis for this line. An investigation has been made of this spectral region in different plasma conditions and the revised description of the spectral lines to be included in the analysis is presented.

  11. Characteristics of low energy atom and molecule beams generated by the charge exchange reaction

    SciTech Connect

    Hara, Yasuhiro; Takashima, Seigo; Toyoda, Hirotaka; Sekine, Makoto; Hori, Masaru; Yamakawa, Koji; Den, Shoji

    2008-03-01

    A low energy NB source, which consisted of a surface wave plasma (SWP) source and two large diameter carbon electrodes, was developed for damageless etching of ultralarge-scale integrated devices. Ion beams were extracted from the SWP using two carbon electrodes, accelerated and injected to the process chamber, and then neutralized without energy loss by a charge exchange reaction. The energy distribution functions of an Ar ion beam and an Ar atom beam was observed using a quadrupole mass spectroscope equipped with an energy analyzer. The energy of the Ar ion beam and the Ar atom beam was controlled by the acceleration voltage. N{sub 2} ion and N ion beams were also extracted from a nitrogen plasma source. The intensity ratio of the N ion beam to the N{sub 2} ion beam was 5:9, indicating that N ions were efficiently generated in the nitrogen SWP. The N{sub 2} ion and N ion beams were changed to N{sub 2} molecule and N atom beams, respectively, through a charge exchange reaction without energy loss. The energy of these beams was controlled by the acceleration voltage and was in the region less of than 100 eV. When the acceleration voltage is higher than 40 V, not only the primary peaks due to the N{sub 2} ion beam or N ion beam were observed but also a low energy second peak was observed in the energy distribution. The energy of the low energy second peak was controlled by the acceleration voltage. It was concluded that the low energy second peak corresponds to the N{sub 2} molecule ion beam and the N ion beam, which is extracted from the second plasma generated in the space between the two carbon electrodes.

  12. Evidence for charge exchange effects in electronic excitations in Al by slow singly charged He ions

    NASA Astrophysics Data System (ADS)

    Riccardi, P.; Sindona, A.; Dukes, C. A.

    2016-09-01

    We report on experiments of secondary electron emission in the interaction of helium ions with aluminum surfaces. Comparison between the electron emission induced by the impact of 3He+ and 4He+ on Al illustrates similarities and differences between the two projectiles. The intensity of emission shows the same dependence on velocity for the two isotopes, showing that KEE yields for helium ions impact on Al are dominated by direct excitation of valence electrons and not by electron promotion. Electron promotion and charge transfer processes are unambiguously identified by the observation of Auger electron emission from Al, at energies below the excitation threshold of Al-Al collisions, indicating energy losses for the projectiles higher than those commonly considered.

  13. Influence of plasma diffusion losses on dust charge relaxation in discharge afterglow

    SciTech Connect

    Coueedel, L.; Mikikian, M.; Boufendi, L.

    2008-09-07

    The influence of diffusive losses on residual dust charge in a complex plasma afterglow has been investigated. The dust residual charges were simulated based on a model developed to describe complex plasma decay. The experimental and simulated data show that the transition from ambipolar to free diffusion in the decaying plasma plays a significant role in determining the residual dust particle charges. The presence of positively charged dust particles is explained by a broadening of the charge distribution function in the afterglow plasma.

  14. Recent Excitation, Charge Exchange, and Lifetime Results in Highly Charged Ions Relevant to Stellar, Interstellar, Solar and Comet Phenomena

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Hossain, S.; Mawhorter, R. J.; Smith, S. J.

    2006-01-01

    Recent JPL absolute excitation and charge exchange cross sections, and measurements of lifetimes of metastable levels in highly-charged ions (HCIs) are reported. These data provide benchmark comparisons to results of theoretical calculations. Theoretical approaches can then be used to calculate the vast array of data which cannot be measured due to experimental constraints. Applications to the X-ray emission from comets are given.

  15. Near resonance charge exchange in ion-atom collisions of lithium isotopes.

    PubMed

    Zhang, Peng; Bodo, Enrico; Dalgarno, Alexander

    2009-12-31

    Collisions of ions and atoms of (6)Li and (7)Li are explored theoretically over a wide range of energy from 10(-14) to 1 eV. Accurate ab initio calculations are carried out of the Born-Oppenheimer potentials and the nonadiabatic couplings that are responsible for the near resonance charge exchange. Scattering studies show that the calculated charge exchange cross section follows Wigner's law for inelastic processes for energies below 10(-10) eV and that the zero temperature rate constant for it is 2.1 x 10(-9) cm(3) s(-1). At collision energies much larger than the isotope shift of the ionization potentials of the atoms, we show that the near resonance charge exchange process is equivalent to the resonance charge exchange with cross sections having a logarithmic dependence on energy. A comparison with the Langevin model at intermediate energies is also presented.

  16. Charge exchange x-ray emission: Astrophysical observations and potential diagnostics

    NASA Astrophysics Data System (ADS)

    Morgan, K.; Andrianarijaona, V.; Draganic, I. N.; Defay, X.; Fogle, M.; Galindo-Uribarri, A.; Guillen, C. I.; Havener, C. C.; Hokin, M.; McCammon, D.; Nader, D. J.; Romano, S. L.; Carcoba, F. Salces; Sauter, P.; Seely, D.; Stancil, P. C.; Vane, C. R.; Vassantachart, A. K.; Wulf, D.

    2013-04-01

    Interest in astrophysical sources of charge exchange X-rays has been growing steadily since the discovery of X-ray emission from the comet Hyakutake with ROSAT in 1996. Since then, charge exchange has been observed between solar wind ions and neutrals in the geocorona and in the atmospheres of Mars and Jupiter. Charge exchange with interstellar neutrals within the heliosphere between solar wind ions and neutral hydrogen and helium from the interstellar medium is now acknowledged as contributing a considerable (although currently unknown) fraction of the soft X-ray background. We make a brief survey of the heliospheric, Galactic, and extragalactic systems in which charge exchange has been observed or is predicted to take place. Experiments measuring velocity dependent cross-section and line ratios for Lyman-series lines and He-like triplets are needed to check current theoretical models of charge exchange emission and aid interpretation of observations. We point out a number of systems that are of astrophysical interest that could be the subject of future laboratory investigations, particularly velocity dependent line ratios of the X-ray emission produced by charge exchange between highly ionized common elements (such as O, C, Ne, and Fe) and atomic hydrogen and helium. To begin to address the need for laboratory data we have measured velocity dependent Ly-series line ratios for C6+ ions interacting with H2, He, and Kr gas targets at Oak Ridge National Laboratory's Ion-Atom Merged-Beams Apparatus.

  17. Neutral atomic oxygen beam produced by ion charge exchange for Low Earth Orbital (LEO) simulation

    NASA Technical Reports Server (NTRS)

    Banks, Bruce; Rutledge, Sharon; Brdar, Marko; Olen, Carl; Stidham, Curt

    1987-01-01

    A low energy neutral atomic oxygen beam system was designed and is currently being assembled at the Lewis Research Center. The system utilizes a 15 cm diameter Kaufman ion source to produce positive oxygen ions which are charge exchange neutralized to produce low energy (variable from 5 to 150 eV) oxygen atoms at a flux simulating real time low Earth orbital conditions. An electromagnet is used to direct only the singly charged oxygen ions from the ion source into the charge exchange cell. A retarding potential grid is used to slow down the oxygen ions to desired energies prior to their charge exchange. Cryogenically cooled diatomic oxygen gas in the charge exchange cell is then used to transfer charge to the oxygen ions to produce a neutral atomic oxygen beam. Remaining non-charge exchanged oxygen ions are then swept from the beam by electromagnetic or electrostatic deflection depending upon the desired experiment configuration. The resulting neutral oxygen beam of 5 to 10 cm in diameter impinges upon target materials within a sample holder fixture that can also provide for simultaneous heating and UV exposure during the atomic oxygen bombardment.

  18. A Method for Estimating the Probability of Floating Gate Prompt Charge Loss in a Radiation Environment

    NASA Technical Reports Server (NTRS)

    Edmonds, L. D.

    2016-01-01

    Because advancing technology has been producing smaller structures in electronic circuits, the floating gates in modern flash memories are becoming susceptible to prompt charge loss from ionizing radiation environments found in space. A method for estimating the risk of a charge-loss event is given.

  19. A Method for Estimating the Probability of Floating Gate Prompt Charge Loss in a Radiation Environment

    NASA Technical Reports Server (NTRS)

    Edmonds, L. D.

    2016-01-01

    Since advancing technology has been producing smaller structures in electronic circuits, the floating gates in modern flash memories are becoming susceptible to prompt charge loss from ionizing radiation environments found in space. A method for estimating the risk of a charge-loss event is given.

  20. Significance of anion exchange in pentachlorophenol sorption by variable-charge soils.

    PubMed

    Hyun, Seunghun; Lee, Linda S; Rao, P Suresh C

    2003-01-01

    Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH-and pKa-dependent chemical speciation and using two organic carbon-normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl2, CaSO4, Ca(H2PO4)2 as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl2 and Ca(H2PO4)2 solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides. PMID:12809297

  1. Significance of anion exchange in pentachlorophenol sorption by variable-charge soils.

    PubMed

    Hyun, Seunghun; Lee, Linda S; Rao, P Suresh C

    2003-01-01

    Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH-and pKa-dependent chemical speciation and using two organic carbon-normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl2, CaSO4, Ca(H2PO4)2 as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl2 and Ca(H2PO4)2 solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides.

  2. Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source

    SciTech Connect

    Jeong, S. C.; Oyaizu, M.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Miyatake, H.; Niki, K.; Okada, M.; Watanabe, Y. X.; Otokawa, Y.; Osa, A.; Ichikawa, S.

    2012-02-15

    We investigated the ion-loss distribution on the sidewall of an electron cyclotron resonance (ECR) plasma chamber using the 18-GHz ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex (TRIAC). Similarities and differences between the ion-loss distributions (longitudinal and azimuthal) of different ion species (i.e., radioactive {sup 111}In{sup 1+} and {sup 140}Xe{sup 1+} ions that are typical volatile and nonvolatile elements) was qualitatively discussed to understand the element dependence of the charge breeding efficiency. Especially, the similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.

  3. Charge Loss and Charge Sharing Measurements for Two Different Pixelated Cadmium-Zinc-Telluride Detectors

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica; Sharma, Dharma; Ramsey, Brian; Seller, Paul

    2003-01-01

    As part of ongoing research at Marshall Space Flight Center, Cadmium-Zinc- Telluride (CdZnTe) pixilated detectors are being developed for use at the focal plane of the High Energy Replicated Optics (HERO) telescope. HERO requires a 64x64 pixel array with a spatial resolution of around 200 microns (with a 6m focal length) and high energy resolution (< 2% at 60keV). We are currently testing smaller arrays as a necessary first step towards this goal. In this presentation, we compare charge sharing and charge loss measurements between two devices that differ both electronically and geometrically. The first device consists of a 1-mm-thick piece of CdZnTe that is sputtered with a 4x4 array of pixels with pixel pitch of 750 microns (inter-pixel gap is 100 microns). The signal is read out using discrete ultra-low-noise preamplifiers, one for each of the 16 pixels. The second detector consists of a 2-mm-thick piece of CdZnTe that is sputtered with a 16x16 array of pixels with a pixel pitch of 300 microns (inter-pixel gap is 50 microns). Instead of using discrete preamplifiers, the crystal is bonded to an ASIC that provides all of the front-end electronics to each of the 256 pixels. what degree the bias voltage (i.e. the electric field) and hence the drift and diffusion coefficients affect our measurements. Further, we compare the measured results with simulated results and discuss to

  4. Laboratory simulation of charge exchange-produced X-ray emission from comets.

    PubMed

    Beiersdorfer, P; Boyce, K R; Brown, G V; Chen, H; Kahn, S M; Kelley, R L; May, M; Olson, R E; Porter, F S; Stahle, C K; Tillotson, W A

    2003-06-01

    In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory.

  5. X-ray Signature of Charge Exchange in the Spectra of L-shell Iron Ions

    SciTech Connect

    Beiersdorfer, P; Schweikhard, L; Liebisch, P; Brown, G V

    2007-01-05

    The X-ray signature of charge exchange between highly charged L-shell iron ions and neutral gas atoms was studied in the laboratory in order to assess its diagnostic utility. Significant differences with spectra formed by electron-impact excitation were observed. In particular, a strong enhancement was found of the emission corresponding to n {le} 4 {yields} n = 2 transitions relative to the n = 3 {yields} n = 2 emission. This enhancement was detectable even with relatively low-resolution X-ray instrumentation (E/{Delta}E {approx} 10) and may enable future identification of charge exchange as a line-formation mechanism in astrophysical spectra.

  6. Laboratory simulation of charge exchange-produced X-ray emission from comets.

    PubMed

    Beiersdorfer, P; Boyce, K R; Brown, G V; Chen, H; Kahn, S M; Kelley, R L; May, M; Olson, R E; Porter, F S; Stahle, C K; Tillotson, W A

    2003-06-01

    In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory. PMID:12791989

  7. 78 FR 6263 - Exchange Visitor Program-Fees and Charges

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-30

    ... published a final rule on November 1, 2007 (72 FR 61800), which became effective December 3, 2007. The 2007... requesting individual program services. The Department published a final rule on February 25, 2011 (76 FR... the Administrative Fee for Exchange Visitor (J-1 Visa Holder) Benefits assessed for providing...

  8. 75 FR 60674 - Exchange Visitor Program-Fees and Charges

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-01

    ... and Budget (OMB) Circular No. A-25, user fees for Exchange Visitor Program Services were adopted for... for certain services for which application is required were adopted. OMB Circular No. A-25 directs the... final rule was amended by a rule dated October 7, 1999 (4 FR 54538), and also by a second rule...

  9. Band bending effect induced by gate voltage on the charge loss behavior of charge trap flash memory devices

    NASA Astrophysics Data System (ADS)

    Chang, M.; Hwang, H.; Jeon, S.

    2010-02-01

    We found that the polarity of the gate voltage (Vg) during the retention characteristics for a SiO2/Si3N4/Al2O3 (ONA) stack can affect the charge loss direction, due to band bending. Positive Vg could induce electron de-trapping through Al2O3, while a negative Vg could induce the same through SiO2. Consequently, the charge loss rates exhibited a hairpin curve with Vg. We clearly observed that increases of the SiO2 thickness of the ONA stack induced negative shifts of hairpin curve. This result suggests that the dominant charge loss path could be changed from SiO2 to Al2O3 by increasing the SiO2 thickness without Vg.

  10. A review of studies on ion thruster beam and charge-exchange plasmas

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1982-01-01

    Various experimental and analytical studies of the primary beam and charge-exchange plasmas of ion thrusters are reviewed. The history of plasma beam research is recounted, emphasizing experiments on beam neutralization, expansion of the beam, and determination of beam parameters such as electron temperature, plasma density, and plasma potential. The development of modern electron bombardment ion thrusters is treated, detailing experimental results. Studies on charge-exchange plasma are discussed, showing results such as the relationship between neutralizer emission current and plasma beam potential, ion energies as a function of neutralizer bias, charge-exchange ion current collected by an axially moving Faraday cup-RPA for 8-cm and 30-cm ion thrusters, beam density and potential data from a 15-cm ion thruster, and charge-exchange ion flow around a 30-cm thruster. A 20-cm thruster electrical configuration is depicted and facility effects are discussed. Finally, plasma modeling is covered in detail for plasma beam and charge-exchange plasma.

  11. Tritium permeation losses in HYLIFE-II heat exchanger tubes

    SciTech Connect

    Longhurst, G.R.; Dolan, T.J.

    1990-01-01

    Tritium permeation through the intermediate heat exchanger of the HYLIFE-II inertial fusion design concept is evaluated for routine operating conditions. The permeation process is modelled using the Lewis analogy combined with surface recombination. It is demonstrated that at very low driving potentials, permeation becomes proportional to the first power of the driving potential. The model predicts that under anticipated conditions the primary cooling loop will pass about 6% of the tritium entering it to the intermediate coolant. Possible approached to reducing tritium permeation are explored. Permeation is limited by turbulent diffusion transport through the molten salt. Hence, surface barriers with impendance factors typical of present technology can do very little to reduce permeation. Low Flibe viscosity is desirable. An efficient tritium removal system operating on the Flibe before it gets to the intermediate heat exchanger is required. Needs for further research are highlighted. 9 refs., 2 figs., 1 tab.

  12. 26 CFR 1.988-2 - Recognition and computation of exchange gain or loss.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 10 2011-04-01 2011-04-01 false Recognition and computation of exchange gain or loss. 1.988-2 Section 1.988-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Export Trade Corporations § 1.988-2 Recognition and computation of exchange gain or...

  13. Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source

    SciTech Connect

    Jeong, S. C.; Oyaizu, M.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Miyatake, H.; Niki, K.; Okada, M.; Watanabe, Y. X.; Otokawa, Y.; Osa, A.; Ichikawa, S.

    2011-03-15

    The ion loss distribution in an electron cyclotron resonance ion source (ECRIS) was investigated to understand the element dependence of the charge breeding efficiency in an electron cyclotron resonance (ECR) charge breeder. The radioactive {sup 111}In{sup 1+} and {sup 140}Xe{sup 1+} ions (typical nonvolatile and volatile elements, respectively) were injected into the ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex to breed their charge states. Their respective residual activities on the sidewall of the cylindrical plasma chamber of the source were measured after charge breeding as functions of the azimuthal angle and longitudinal position and two-dimensional distributions of ions lost during charge breeding in the ECRIS were obtained. These distributions had different azimuthal symmetries. The origins of these different azimuthal symmetries are qualitatively discussed by analyzing the differences and similarities in the observed wall-loss patterns. The implications for improving the charge breeding efficiencies of nonvolatile elements in ECR charge breeders are described. The similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.

  14. Apparent violation of the sum rule for exchange-correlation charges by generalized gradient approximations.

    PubMed

    Kohut, Sviataslau V; Staroverov, Viktor N

    2013-10-28

    The exchange-correlation potential of Kohn-Sham density-functional theory, vXC(r), can be thought of as an electrostatic potential produced by the static charge distribution qXC(r) = -(1∕4π)∇(2)vXC(r). The total exchange-correlation charge, QXC = ∫qXC(r) dr, determines the rate of the asymptotic decay of vXC(r). If QXC ≠ 0, the potential falls off as QXC∕r; if QXC = 0, the decay is faster than coulombic. According to this rule, exchange-correlation potentials derived from standard generalized gradient approximations (GGAs) should have QXC = 0, but accurate numerical calculations give QXC ≠ 0. We resolve this paradox by showing that the charge density qXC(r) associated with every GGA consists of two types of contributions: a continuous distribution and point charges arising from the singularities of vXC(r) at each nucleus. Numerical integration of qXC(r) accounts for the continuous charge but misses the point charges. When the point-charge contributions are included, one obtains the correct QXC value. These findings provide an important caveat for attempts to devise asymptotically correct Kohn-Sham potentials by modeling the distribution qXC(r). PMID:24182014

  15. Removal of charged micropollutants from water by ion-exchange polymers -- effects of competing electrolytes.

    PubMed

    Bäuerlein, Patrick S; Ter Laak, Thomas L; Hofman-Caris, Roberta C H M; de Voogt, Pim; Droge, Steven T J

    2012-10-15

    A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H(2)O(2), activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca(2+) solutions compared to similar concentrations of Na(+), while that of anionic compounds is three fold weaker in SO(4)(2-) solutions compared to equal concentrations of Cl(-). PMID:22818952

  16. Two-stage Rydberg charge exchange: An efficient method for production of antihydrogen

    SciTech Connect

    Hessels, E.A.; Homan, D.M.; Cavagnero, M.J.

    1998-03-01

    An efficient method for production of cold antihydrogen ({bar H}) is proposed. Alkali-metal atoms laser excited to a Rydberg state are charge exchanged with cold trapped positrons, producing Rydberg states of positronium. In a second Rydberg-state charge exchange, the positronium atoms give up their Rydberg positrons to cold trapped antiprotons, producing Rydberg states of {bar H}. These {bar H} atoms soon decay down to the ground state, and, because they are cold, could be trapped in a magnetic trap. The efficiency of the process results from the extremely large cross sections for Rydberg charge exchange. Classical trajectory Monte Carlo calculations indicate an {bar H} instantaneous production rate of 10{sup 6}/s. {copyright} {ital 1998} {ital The American Physical Society}

  17. The influence of charge exchange on the velocity distribution of hydrogen in the Venus exosphere

    NASA Technical Reports Server (NTRS)

    Hodges, Richard R., Jr.; Tinsley, Brian A.

    1986-01-01

    The simulation of the exosphere of Venus by a Monte Carlo technique has been extended to provide velocity distribution profiles that can be used with radiative transfer simulation to model the Lyman-alpha emission seen by spacecraft. The line profiles show a narrow core due to the exobase thermal source of hydrogen superimposed on the broad profile of hot hydrogen from charge exchange with hot ions in the nighttime ionosphere. Nightside radial profiles show long tails of upward flowing, escaping atoms. There are some downward and lateral superescape signatures, because the charge exchange source extends well above the exobase. At higher altitudes, flattening and even shallow central valleys appear in the transverse profiles. The planetary average escape rate due to charge exchange was found to be 2.8 x 10 to the 7th/sq cm per s, which is several times larger than escape rates for other candidate mechanisms.

  18. Experimental discovery of charge-exchange-caused dips in spectral lines from laser-produced plasmas.

    PubMed

    Leboucher-Dalimier, E; Oks, E; Dufour, E; Sauvan, P; Angelo, P; Schott, R; Poquerusse, A

    2001-12-01

    We report the first experimental observation of charge-exchange-caused dips (also called x dips) in spectral lines of multicharged ions in laser-produced plasmas. Specifically, in the process of a laser irradiation of targets made out of aluminum carbide, we observed two x dips in the Ly(gamma) line of Al XIII perturbed by fully stripped carbon. From the practical point of view, this opens up a way to experimentally produce not-yet-available fundamental data on charge exchange between multicharged ions, virtually inaccessible by other experimental methods. From the theoretical viewpoint, the results are important because the x dips are the only one signature of charge exchange in profiles of spectral lines emitted by plasmas and they are the only one quasimolecular phenomenon that could be observed at relatively "low" densities of laser-produced plasmas. PMID:11736229

  19. Charge exchange in C^6+ + H and C^6+ + H2 collisions

    NASA Astrophysics Data System (ADS)

    Guevara-Leon, Nicolais; Saha, Bidhan; Sabin, John R.; Deumens, Erik; Ohrn, N. Y.

    2010-03-01

    In the solar wind, C^6+ ion is one of the most abundant ionic species and its interaction with comets as well as the atmosphere of planets of the solar system produces several interesting phenomena. The charge exchange reaction is one of the most relevant process as it may provide a possible explanation for the X-ray emission from these objects. Electron capture into a highly excited state of C^5+ ion usually generates radiation in the X-ray region of the spectrum. In the present work, charge exchange in C^6+ + H and C^6+ + H2 collisions are investigated theoretically using electron nuclear dynamics (END) [1] at projectile energies below the ionization threshold. For H2 the one- and two- electron charge exchange cross sections are calculated and compared with other theoretical and experimental data. Orientation effects for the collision with the hydrogen molecules will also be discussed at the conference.

  20. Influence of hearing loss and cognitive abilities on language development in CHARGE Syndrome.

    PubMed

    Vesseur, Annemarie; Langereis, Margreet; Free, Rolien; Snik, Ad; van Ravenswaaij-Arts, Conny; Mylanus, Emmanuel

    2016-08-01

    Hearing loss and cognitive delay are frequently occurring features in CHARGE syndrome that may contribute to impaired language development. However, not much is known about language development in patients with CHARGE syndrome. In this retrospective study, hearing loss, cognitive abilities, and language development are described in 50 patients with CHARGE syndrome. After informed consent was given, data were collected from local medical files. Most patients (38.3%; 18/47 patients) had moderate hearing loss (41-70 dB) and 58.5% (24/41 patients) had an IQ below 70. The mean language quotients of the receptive and expressive language were more than one standard deviation below the norm. Both hearing loss and cognitive delay had an influence on language development. Language and cognitive data were not available for all patients, which may have resulted in a pre-selection of patients with a delay. In conclusion, while hearing thresholds, cognitive abilities and language development vary widely in CHARGE syndrome, they are mostly below average. Hearing loss and cognitive delay have a significant influence on language development in children with CHARGE syndrome. To improve our knowledge about and the quality of care we can provide to CHARGE patients, hearing and developmental tests should be performed regularly in order to differentiate between the contributions of hearing loss and cognitive delay to delays in language development, and to provide adequate hearing amplification in the case of hearing loss. © 2016 Wiley Periodicals, Inc. PMID:27145116

  1. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

    PubMed

    Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ.

  2. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

    PubMed

    Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ. PMID:27126470

  3. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

    NASA Astrophysics Data System (ADS)

    Vaikkinen, Anu; Kauppila, Tiina J.; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M+. decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques.

  4. Charge-noise tolerant exchange gates of singlet-triplet qubits in asymmetric double quantum dots

    NASA Astrophysics Data System (ADS)

    Hiltunen, Tuukka; Bluhm, Hendrik; Mehl, Sebastian; Harju, Ari

    2015-02-01

    In the semiconductor double quantum dot singlet-triplet qubit architecture, the decoherence caused by the qubit's charge environment poses a serious obstacle towards large scale quantum computing. The effects of the charge decoherence can be mitigated by operating the qubit in the so-called sweet spot regions where it is insensitive to electrical noise. In this paper, we propose singlet-triplet qubits based on two quantum dots of different sizes. Such asymmetric double quantum dot systems allow the implementation of exchange gates with controllable exchange splitting J operated in the doubly occupied charge region of the larger dot, where the qubit has high resilience to charge noise. In the larger dot, J can be quenched to a value smaller than the intradot tunneling using magnetic fields, while the smaller dot and its larger splitting can be used in the projective readout of the qubit.

  5. Charge exchange and ionization in hydrogen atom-fully stripped ion collisions in Debye plasmas

    SciTech Connect

    Zhang, H.; Wang, J. G.; He, B.; Qiu, Y. B.; Janev, R. K.

    2007-05-15

    The processes of charge exchange and ionization in collisions of ground state hydrogen atom with fully stripped ions in a weakly coupled plasma are studied by the classical trajectory Monte Carlo method in the collision energy range 10-900 keV/amu. The interparticle interactions are described by the Debye-Hueckel model with inclusion of dynamical effects associated with the projectile velocity. The microcanonical distribution of initial state electronic coordinates and momenta has been determined by inclusion of plasma screening effects. The cross section dependencies on plasma parameters and ion charge and velocity are investigated. It is shown that plasma effects on charge exchange and ionization cross sections are significant and particularly pronounced at low collision velocities. The results of systematic cross section calculations for different values of Debye screening length (in the range 1-50a{sub 0}) and ion charges (in the range 1-14) are presented.

  6. Simulation of charge exchange plasma propagation near an ion thruster propelled spacecraft

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.; Kaufman, H. R.; Winder, D. R.

    1981-01-01

    A model describing the charge exchange plasma and its propagation is discussed, along with a computer code based on the model. The geometry of an idealized spacecraft having an ion thruster is outlined, with attention given to the assumptions used in modeling the ion beam. Also presented is the distribution function describing charge exchange production. The barometric equation is used in relating the variation in plasma potential to the variation in plasma density. The numerical methods and approximations employed in the calculations are discussed, and comparisons are made between the computer simulation and experimental data. An analytical solution of a simple configuration is also used in verifying the model.

  7. Interaction of a solar array with an ion thruster due to the charge-exchange plasma

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1976-01-01

    The generation of a charge exchange plasma by a thruster, the transport of this plasma to the solar array, and the interaction of the solar array with the plasma after it arrives are all described. The generation of this plasma is described accurately from thruster geometry and operating conditions. The transport of the charge exchange plasma was studied experimentally with a 15 cm thruster. A model was developed for simple thruster array configurations. A variety of experiments were surveyed for the interaction of the plasma at the solar array.

  8. Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, B.

    2003-01-01

    The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory to study the X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in the existing experimental and theoretical data and are needed to explain all or part of the observed X-ray emission from the Galactic Ridge, solar and stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae.

  9. Unstable ring-shaped ion distribution functions induced by charge-exchange collisions

    NASA Astrophysics Data System (ADS)

    Miloch, W. J.; Pécseli, H. L.; Trulsen, J. K.

    2013-12-01

    The stability of ion velocity distributions in magnetized plasmas is studied under conditions where the plasma has an E0 × B/B2-drift with respect to a neutral background. Charge-exchange collisions can give rise to velocity distributions having the form of a ring or a loss-cone that can become linearly unstable. Sometimes the distributions have distorted forms and a stability analysis is not straightforward. Numerical simulations offer the most convenient method of a stability analysis in such cases. By numerical simulations using a particle-in-cell code that includes collisional interactions we demonstrate the formation of such velocity distributions and study the instabilities associated with them. We observe the saturation of the linear instability by quasi-linear velocity space diffusion. The parameter dependence of the instability conditions is illustrated by examples. The results are relevant for explaining some of the low frequency oscillations observed in the lower parts of the Earth's ionosphere (E- and F-regions), where collisions with neutrals are abundant. The results are important for laboratory experiments as well.

  10. Signature of X-ray Line Formation of Fe XVII by Charge Exchange

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter

    Fe XVII dominates the spectral emission of a large number of astrophysical X-ray sources and, thus, is of prime diagnostic importance, as illustrated in numerous measurements by Chandra and XMM-Newton. Although immense progress has been made in laboratory measurements and spectral calculations of collisional plasmas since the launch of these X-ray observatories, model calculations of the Fe XVII X-ray spectrum still do not yield agreement with laboratory measurements or astrophysical observations that is completely satisfactory. Charge exchange is another line formation mechanism that can produce Fe XVII X-ray emission. However, line formation by charge exchange is ill understood, even in the case of 'simple' K-shell spectra of hydrogenlike or heliumlike ions. Nevertheless, simple spectral markers have been developed that represent proof for the presence of charge exchange even if the details of line formation are not yet fully clear. By contrast, there are essentially no charge exchange measurements and calculations for the much more complex Fe XVII L-shell X-ray spectrum. Whether charge exchange contributes an observable amount to X-ray line formation in astrophysical situations is controversial, as (arguably) no incontrovertible spectral evidence for charge exchange has been presented from sources outside our own solar system. In part, this is due to the fact that charge exchange is a mechanism that requires an extended source to be effective, such as circum-stellar halos or super nova remnants expanding into surrounding space, and so far there have been no measurements of extended sources with high spectral resolution. In addition, laboratory measurements have not yet provided data that could serve as spectral markers for charge exchange in the Fe XVII spectrum or, for that matter, in the other L-shell X-ray emission spectra of iron, i.e., Fe XVIII through Fe XXIV. As a result, it is not yet possible to argue that an observed iron L-shell X-ray spectrum is

  11. Discontinuous gas exchange, water loss, and metabolism in Protaetia cretica (Cetoniinae, Scarabaeidae).

    PubMed

    Matthews, Philip G D; White, Craig R

    2012-01-01

    Insects are at high risk of desiccation because of their small size, high surface-area-to-volume ratio, and air-filled tracheal system that ramifies throughout their bodies to transport O(2) and CO(2) to and from respiring cells. Although the tracheal system offers a high-conductance pathway for the movement of respiratory gases, it has the unintended consequence of allowing respiratory transpiration to the atmosphere. When resting, many species exchange respiratory gases discontinuously, and an early hypothesis for the origin of these discontinuous gas exchange cycles (DGCs) is that they serve to reduce respiratory water loss. In this study, we test this "hygric" hypothesis by comparing rates of CO(2) exchange and water loss among flower beetles Protaetia cretica (Cetoniinae, Scarabaeidae) breathing either continuously or discontinuously. We show that, consistent with the expectations of the hygric hypothesis, rates of total water loss are higher during continuous gas exchange than during discontinuous gas exchange and that the ratio of respiratory water loss to CO(2) exchange is lower during discontinuous gas exchange. This conclusion is in agreement with other studies of beetles and cockroaches that also support the hygric hypothesis. However, this result does not exclude other adaptive hypotheses supported by work on ants and moth pupae. This ambiguity may arise because there are multiple independent evolutionary origins of DGCs and no single adaptive function underlying their genesis. Alternatively, the observed reduction in water loss during DGCs may be a side effect of a nonadaptive gas exchange pattern that is elicited during periods of inactivity.

  12. Discontinuous gas exchange, water loss, and metabolism in Protaetia cretica (Cetoniinae, Scarabaeidae).

    PubMed

    Matthews, Philip G D; White, Craig R

    2012-01-01

    Insects are at high risk of desiccation because of their small size, high surface-area-to-volume ratio, and air-filled tracheal system that ramifies throughout their bodies to transport O(2) and CO(2) to and from respiring cells. Although the tracheal system offers a high-conductance pathway for the movement of respiratory gases, it has the unintended consequence of allowing respiratory transpiration to the atmosphere. When resting, many species exchange respiratory gases discontinuously, and an early hypothesis for the origin of these discontinuous gas exchange cycles (DGCs) is that they serve to reduce respiratory water loss. In this study, we test this "hygric" hypothesis by comparing rates of CO(2) exchange and water loss among flower beetles Protaetia cretica (Cetoniinae, Scarabaeidae) breathing either continuously or discontinuously. We show that, consistent with the expectations of the hygric hypothesis, rates of total water loss are higher during continuous gas exchange than during discontinuous gas exchange and that the ratio of respiratory water loss to CO(2) exchange is lower during discontinuous gas exchange. This conclusion is in agreement with other studies of beetles and cockroaches that also support the hygric hypothesis. However, this result does not exclude other adaptive hypotheses supported by work on ants and moth pupae. This ambiguity may arise because there are multiple independent evolutionary origins of DGCs and no single adaptive function underlying their genesis. Alternatively, the observed reduction in water loss during DGCs may be a side effect of a nonadaptive gas exchange pattern that is elicited during periods of inactivity. PMID:22418709

  13. Pion-nucleon charge exchange amplitudes above 2 GeV

    NASA Astrophysics Data System (ADS)

    Huang, F.; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meißner, U.-G.

    2009-04-01

    The amplitudes for the pion-nucleon charge exchange reaction of the Karlsruhe-Helsinki and the George-Washington-University partial-wave analyses are compared with those of a Regge-cut model with the aim to explore the possibility to provide high-energy constraints for theoretical baryon resonance analyses in the energy region above 2GeV.

  14. Population inversion calculations using near resonant charge exchange as a pumping mechanism

    NASA Technical Reports Server (NTRS)

    Chubb, D. L.; Rose, J. R.

    1972-01-01

    Near resonance charge exchange between ions of a large ionization potential gas such as helium or neon and vapors of metals such as zinc, cadmium, selenium, or tellurium has produced laser action in the metal ion gas. The possibility of obtaining population inversions in near resonant charge exchange systems (Xe-Ca, Xe-Mg, Xe-Sr, Xe-Ba, Ar-Mg, N-Ca) was investigated. The analysis is an initial value problem that utilizes rate equations for the densities of relevant levels of the laser gas (Ca, Ba, Mg, or Sr) and an electron energy equation. Electron excitation rates are calculated using the Bohr-Thomson approximation for the cross section. Approximations to experimental values of the electron ionization cross section and the ion-atom charge exchange cross section are used. Preliminary results have been obtained for the Ca-Xe system and show that it is possible to obtain gains greater than 10 to the 14th power/m with inversion times up to 8x10 to the minus 7th power second. A possible charge exchange laser system using a MPD arc plasma accelerator is also described.

  15. Short-range NN and N. Delta. correlations in pion double charge exchange (DCX)

    SciTech Connect

    Johnson, M.B.

    1990-01-01

    I will review several important results related to the short-range nucleon-nucleon and delta-nucleon interaction that have been obtained from recent studies of pion double charge exchange in selected nuclei. 32 refs., 5 figs., 3 tabs.

  16. Charge loss (or the lack thereof) for AdS black holes

    NASA Astrophysics Data System (ADS)

    Ong, Yen Chin; Chen, Pisin

    2014-06-01

    The evolution of evaporating charged black holes is complicated to model in general, but is nevertheless important since the hints to the Information Loss Paradox and its recent firewall incarnation may lie in understanding more generic geometries than that of Schwarzschild spacetime. Fortunately, for sufficiently large asymptotically flat Reissner-Nordström black holes, the evaporation process can be modeled via a system of coupled linear ordinary differential equations, with charge loss rate governed by Schwinger pair-production process. The same model can be generalized to study the evaporation of AdS Reissner-Nordström black holes with flat horizon. It was recently found that such black holes always evolve towards extremality since charge loss is inefficient. This property is completely opposite to the asymptotically flat case in which the black hole eventually loses its charges and tends towards Schwarzschild limit. We clarify the underlying reason for this different behavior.

  17. Charged fusion product loss measurements using nuclear activation

    SciTech Connect

    Bonheure, G.; Hult, M.; Gonzalez de Orduna, R.; Wieslander, E.; Arnold, D.; Dombrowski, H.; Laubenstein, M.; Murari, A.; Collaboration: JET-EFDA Contributors

    2010-10-15

    In ITER, {alpha} particle loss measurements will be required in order to understand the alpha particle physics. Techniques capable of operating in a fusion reactor environment need further development. Recent experimental studies on JET demonstrated the potential of nuclear activation to measure the flux of escaping MeV ions. New results from MeV ion induced activation of metallic, ceramic, and crystal samples placed near the plasma edge are reported. Activation products were measured as function of orientation with respect to the magnetic field as well as function of the distance to the plasma. Sample activity was measured using ultralow-level gamma-ray spectrometry. Distribution of 14.68 MeV fusion proton induced activation products is strongly anisotropic in agreement with simulations and falls off sharply with increasing distance to the plasma. Prospects for using the technique in ITER are discussed.

  18. 26 CFR 1.741-1 - Recognition and character of gain or loss on sale or exchange.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Recognition and character of gain or loss on sale or exchange. 1.741-1 Section 1.741-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE... Recognition and character of gain or loss on sale or exchange. (a) The sale or exchange of an interest in...

  19. A demonstration of beam intensity modulation without loss of charge

    SciTech Connect

    Mackenzie, G.H.; Rawnsley, W.R.; Lee, R.

    1995-09-01

    The large acceptance and the simplicity of H{sup {minus}} extraction makes practical unusual modes of cyclotron operation. RF equipment, initially installed for H{sup {minus}} extraction at TRIUMF, has been used to modulate the beam intensity at the extraction radius. This equipment consists of a 92 MHz, 150 kV cavity (AAC) and an RFD (11.5 MHz, 20 kV). The AAC augments the acceleration provided by the main 23 MHz, RF system; the RFD excites radial betatron oscillations. These devices may be operated at frequencies slightly different from their design multiple; their effect then beats with the main RF. In this mode the AAC, for example, alternately reduces the rate of acceleration, thus increasing the overlap of turns, then enhances it, sweeping the clustered turns onto a probe or foil. Operating the AAC or RFD in this manner gathers the bulk of the charge into peaks a few microseconds wide and spaced between 6 and 50 {micro}s. Changing the frequency offset alters the spacing. The peak to valley ratio was 23:1 and all beam was transmitted to the extraction radius.

  20. Pipkin Award Talk: Rydberg Charge Exchange: A Method for Producing Rydberg Positronium and Antihydrogen Atoms

    NASA Astrophysics Data System (ADS)

    Hessels, E. A.

    2003-05-01

    Antihydrogen production via two-stage charge exchange(E.A.Hessels, D.M. Homan and M.J. Cavagnero, Phys. Rev. A. 57), (1998) 1668. may provide extremely cold antimatter atoms that can be trapped for spectroscopic studies. Positrons(J. Estrada, T. Roach, J.N. Tan, P. Yesley, and G. Gabrielse, Phys. Rev. Lett. 84), (2000) 859. and antiprotons(G. Gabrielse, N. S. Bowden, P. Oxley, A. Speck, C. H. Storry, J. N. Tan, M. Wessels, D. Grozonka, W. Oelert, G. Schepers, T. Sefzick, J. Walz, H. Pittner, T. W. Hansch, E. A. Hessels, Phys. Lett. B 548), (2002) 140-145., both cooled to 4 K and loaded into adjacent wells of a Penning trap, provide the basic components. Laser-excited Rydberg cesium atoms are passed through the cloud of trapped positrons and charge exchange with the positrons to form Rydberg states of positronium. These positronium atoms have been observed and are studied by ionizing them and counting the resulting positrons. State analysis of the positronium is obtained by varying the electric field used to ionize the atoms. Large numbers of positronium atoms are produced and their binding energies are found to be similar to that of the incoming Rydberg cesium atoms. A second charge exchange is proposed, in which the neutral positronium travels a short distance to an adjacent antiproton cloud. The result of this second charge exchange would be antihydrogen atoms. The apparatus to test this second charge exchange has already been constructed and preliminary studies have already been made.

  1. Charge-dependent many-body exchange and dispersion interactions in combined QM/MM simulations

    NASA Astrophysics Data System (ADS)

    Kuechler, Erich R.; Giese, Timothy J.; York, Darrin M.

    2015-12-01

    Accurate modeling of the molecular environment is critical in condensed phase simulations of chemical reactions. Conventional quantum mechanical/molecular mechanical (QM/MM) simulations traditionally model non-electrostatic non-bonded interactions through an empirical Lennard-Jones (LJ) potential which, in violation of intuitive chemical principles, is bereft of any explicit coupling to an atom's local electronic structure. This oversight results in a model whereby short-ranged exchange-repulsion and long-ranged dispersion interactions are invariant to changes in the local atomic charge, leading to accuracy limitations for chemical reactions where significant atomic charge transfer can occur along the reaction coordinate. The present work presents a variational, charge-dependent exchange-repulsion and dispersion model, referred to as the charge-dependent exchange and dispersion (QXD) model, for hybrid QM/MM simulations. Analytic expressions for the energy and gradients are provided, as well as a description of the integration of the model into existing QM/MM frameworks, allowing QXD to replace traditional LJ interactions in simulations of reactive condensed phase systems. After initial validation against QM data, the method is demonstrated by capturing the solvation free energies of a series of small, chlorine-containing compounds that have varying charge on the chlorine atom. The model is further tested on the SN2 attack of a chloride anion on methylchloride. Results suggest that the QXD model, unlike the traditional LJ model, is able to simultaneously obtain accurate solvation free energies for a range of compounds while at the same time closely reproducing the experimental reaction free energy barrier. The QXD interaction model allows explicit coupling of atomic charge with many-body exchange and dispersion interactions that are related to atomic size and provides a more accurate and robust representation of non-electrostatic non-bonded QM/MM interactions.

  2. Charge-dependent many-body exchange and dispersion interactions in combined QM/MM simulations.

    PubMed

    Kuechler, Erich R; Giese, Timothy J; York, Darrin M

    2015-12-21

    Accurate modeling of the molecular environment is critical in condensed phase simulations of chemical reactions. Conventional quantum mechanical/molecular mechanical (QM/MM) simulations traditionally model non-electrostatic non-bonded interactions through an empirical Lennard-Jones (LJ) potential which, in violation of intuitive chemical principles, is bereft of any explicit coupling to an atom's local electronic structure. This oversight results in a model whereby short-ranged exchange-repulsion and long-ranged dispersion interactions are invariant to changes in the local atomic charge, leading to accuracy limitations for chemical reactions where significant atomic charge transfer can occur along the reaction coordinate. The present work presents a variational, charge-dependent exchange-repulsion and dispersion model, referred to as the charge-dependent exchange and dispersion (QXD) model, for hybrid QM/MM simulations. Analytic expressions for the energy and gradients are provided, as well as a description of the integration of the model into existing QM/MM frameworks, allowing QXD to replace traditional LJ interactions in simulations of reactive condensed phase systems. After initial validation against QM data, the method is demonstrated by capturing the solvation free energies of a series of small, chlorine-containing compounds that have varying charge on the chlorine atom. The model is further tested on the SN2 attack of a chloride anion on methylchloride. Results suggest that the QXD model, unlike the traditional LJ model, is able to simultaneously obtain accurate solvation free energies for a range of compounds while at the same time closely reproducing the experimental reaction free energy barrier. The QXD interaction model allows explicit coupling of atomic charge with many-body exchange and dispersion interactions that are related to atomic size and provides a more accurate and robust representation of non-electrostatic non-bonded QM/MM interactions.

  3. Charge-dependent many-body exchange and dispersion interactions in combined QM/MM simulations.

    PubMed

    Kuechler, Erich R; Giese, Timothy J; York, Darrin M

    2015-12-21

    Accurate modeling of the molecular environment is critical in condensed phase simulations of chemical reactions. Conventional quantum mechanical/molecular mechanical (QM/MM) simulations traditionally model non-electrostatic non-bonded interactions through an empirical Lennard-Jones (LJ) potential which, in violation of intuitive chemical principles, is bereft of any explicit coupling to an atom's local electronic structure. This oversight results in a model whereby short-ranged exchange-repulsion and long-ranged dispersion interactions are invariant to changes in the local atomic charge, leading to accuracy limitations for chemical reactions where significant atomic charge transfer can occur along the reaction coordinate. The present work presents a variational, charge-dependent exchange-repulsion and dispersion model, referred to as the charge-dependent exchange and dispersion (QXD) model, for hybrid QM/MM simulations. Analytic expressions for the energy and gradients are provided, as well as a description of the integration of the model into existing QM/MM frameworks, allowing QXD to replace traditional LJ interactions in simulations of reactive condensed phase systems. After initial validation against QM data, the method is demonstrated by capturing the solvation free energies of a series of small, chlorine-containing compounds that have varying charge on the chlorine atom. The model is further tested on the SN2 attack of a chloride anion on methylchloride. Results suggest that the QXD model, unlike the traditional LJ model, is able to simultaneously obtain accurate solvation free energies for a range of compounds while at the same time closely reproducing the experimental reaction free energy barrier. The QXD interaction model allows explicit coupling of atomic charge with many-body exchange and dispersion interactions that are related to atomic size and provides a more accurate and robust representation of non-electrostatic non-bonded QM/MM interactions. PMID

  4. Charge-dependent many-body exchange and dispersion interactions in combined QM/MM simulations

    SciTech Connect

    Kuechler, Erich R.; Giese, Timothy J.; York, Darrin M.

    2015-12-21

    Accurate modeling of the molecular environment is critical in condensed phase simulations of chemical reactions. Conventional quantum mechanical/molecular mechanical (QM/MM) simulations traditionally model non-electrostatic non-bonded interactions through an empirical Lennard-Jones (LJ) potential which, in violation of intuitive chemical principles, is bereft of any explicit coupling to an atom’s local electronic structure. This oversight results in a model whereby short-ranged exchange-repulsion and long-ranged dispersion interactions are invariant to changes in the local atomic charge, leading to accuracy limitations for chemical reactions where significant atomic charge transfer can occur along the reaction coordinate. The present work presents a variational, charge-dependent exchange-repulsion and dispersion model, referred to as the charge-dependent exchange and dispersion (QXD) model, for hybrid QM/MM simulations. Analytic expressions for the energy and gradients are provided, as well as a description of the integration of the model into existing QM/MM frameworks, allowing QXD to replace traditional LJ interactions in simulations of reactive condensed phase systems. After initial validation against QM data, the method is demonstrated by capturing the solvation free energies of a series of small, chlorine-containing compounds that have varying charge on the chlorine atom. The model is further tested on the S{sub N}2 attack of a chloride anion on methylchloride. Results suggest that the QXD model, unlike the traditional LJ model, is able to simultaneously obtain accurate solvation free energies for a range of compounds while at the same time closely reproducing the experimental reaction free energy barrier. The QXD interaction model allows explicit coupling of atomic charge with many-body exchange and dispersion interactions that are related to atomic size and provides a more accurate and robust representation of non-electrostatic non-bonded QM

  5. Toward a cold hybrid-trap measurement of charge-exchange between Na and Ca+: Na excited state fraction

    NASA Astrophysics Data System (ADS)

    Wells, James E.; Goodman, Douglas S.; Kwolek, Jonathan M.; Blumel, Reinhold; Narducci, Frank A.; Smith, Winthrop W.

    2015-05-01

    We present progress towards the measurement of the charge-exchange collision rate coefficient between neutral sodium and ionic calcium. The rate constant for charge exchange between ground state sodium and calcium ion has been previously calculated and predicts a lifetime in our system of the order of days. Experiments by our group show a much larger charge exchange collision rate, probably from the excited 3P state of sodium. Therefore, an accurate measurement of the charge exchange collision rate constant will require an accurate value for the excited state fraction of the Na MOT. We have developed a technique for making a model-independent measurement of the excited state fraction of a MOT inside a hybrid trap. We compare the measured excited state fraction using this technique with measurements assuming a two-level model of the atom. In addition, we review our recent measurement of the total elastic and resonant charge exchange collision rate between Na and Na+.

  6. Charge exchange spectroscopy system calibration for ion temperature measurement in KSTARa)

    NASA Astrophysics Data System (ADS)

    Ko, Won-Ha; Lee, Hyungho; Seo, Dongcheol; Kwon, Myeun

    2010-10-01

    The charge exchange spectroscopy (CES) system including collection assemblies, lens design, and cassettes for the KSTAR experiment was installed to obtain profiles of the ion temperature and the toroidal rotation velocity from charge exchange emission between plasma ions and beam neutrals near the plasma axis by using a modulated neutral beam and a background system. We can measure the charge exchange spectra of an impurity line such as the 529 nm line of carbon VI to get ion temperature and rotation profiles in KSTAR. The CES and background systems will have absolute intensity and spectral calibrations using a calibrated source and various spectral lamps. The calibration was done inside the tokamak after all CES systems are installed and the optical systems are slid into the cassettes. This requires that the diagnostic systems are installed near the vacuum vessel inside the cryostat maintaining the superconducting state of the superconducting coils. Repeated spectral calibrations of the spectrometer and charge coupled device for CES will be made in the diagnostic room during the experimental campaign. We show a detailed description of the KSTAR CES system, how to calibrate, and the results of calibration.

  7. Signatures of the electron saddle swaps mechanism in the photon spectra following charge-exchange collisions

    NASA Astrophysics Data System (ADS)

    Otranto, Sebastian

    2014-10-01

    During the last few years, several experimental and theoretical studies have focused on state selective charge exchange processes between charged ions and alkali metals. These data are of particular importance for the tokamak nuclear fusion reactor program, since diagnostics on the plasma usually rely on charge-exchange spectroscopy. In this sense, alkali metals, have been proposed as potential alternatives to excited hydrogen/deuterium for which laboratory experiments are not feasible at present. In this talk, we present our recent work involving ion collisions with alkali metals. Oscillatory structures in the angular differential charge-exchange cross sections obtained using the MOTRIMS technique are correctly described by classical trajectory Monte Carlo simulations. These oscillations are found to originate from the number of swaps the electron undergoes around the projectile-target potential saddle before capture takes place and are very prominent at impact energies below 10 keV/amu. Moreover, cross sections of higher order of differentiability also indicate that the swaps leave distinctive signatures in the (n,l)-state selective cross sections and in the photon line emission cross sections. Oscillatory structures for the x-ray hardness ratio parameter are also predicted. In collaboration with Ronnie Hoekstra, Zernike Institute for Advanced Materials, University of Groningen and Ronald Olson, Department of Physics, Missouri University of Science and Technology.

  8. Discontinuous gas exchange and the significance of respiratory water loss in Scarabaeine beetles.

    PubMed

    Chown, Steven L; Davis, Adrian L V

    2003-10-01

    Respiratory water loss in insects is a controversial topic. Whilst earlier studies considered respiratory transpiration a significant component of overall water loss, to the extent that it was thought to be responsible not only for the evolution of discontinuous gas exchange cycles (DGCs) but also for variation in DGC patterns, later work repeatedly questioned its importance. In particular, investigations of the proportional contribution of respiratory transpiration to total water loss in species showing DGCs suggested that respiratory transpiration was unlikely to be important in these species. In turn, these studies have been criticized on analytical grounds. In this study we investigated variation in cuticular and respiratory water loss rates in five Scarabaeus dung beetle species, all of which show discontinuous gas exchange cycles, to ascertain the significance of respiratory water loss using modern analytical techniques. In particular, we determined whether there is variation in water loss rates amongst these beetles, whether both respiratory and cuticular water loss rates contribute significantly to variation in the former, and whether metabolic rate variation and variation in the duration of the DGC periods contribute significantly to variation in respiratory water loss rate. Total water loss rate varied such that species from arid areas had the lowest rates of water loss, and both cuticular and spiracular transpiration contributed significantly to variation in overall water loss rate. Moreover, variation in metabolic rate and in the duration of the DGC periods contributed significantly to variation in respiratory water loss rate. By contrast, examination of proportional water loss revealed little other than that it varies between 6.5% and 21%, depending on the species and the temperature at which it was examined. Cuticular water loss scaled as mass(0.721), but did not differ from that expected from geometric considerations alone. By contrast, respiratory

  9. Laboratory Studies of X-ray Spectra Formed by Charge Exchange

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter; Ali, R.; Brown, G. V.; Koutroumpa, D.; Kelley, R. L.; Kilbourne, C.; Leutenegger, M. A.; Porter, F.

    2013-04-01

    Charge exchange between ions and neutral atoms or molecules has been accepted at an important soft producing process in our solar system. By extension, charge exchange may contribute to the X-ray emission of circumstellar material. It may also produce X-ray emission at the boundaries of supernova ejecta and star burst galaxies, or whenever hot plasma collides with neutral matter. X-ray spectra of K-shell and L-shell ions formed by charge exchange have now been studied in a variety of laboratory settings. These experiments have shown several characteristic features of line formation by charge exchange when compared to the X-ray emission produced by electron-impact excitation, e.g., enhancement emission of forbidden lines and of lines from levels with high principal quantum number. They have also shown a dependence on the interaction gas and on the energy of the ion-neutral collision. Moreover, the transfer of multiple electrons is typically preferred, provided the donor molecules or atoms have multiple valence-shell electrons. The laboratory measurements are in qualitative agreement with theory. However, the details of the observed X-ray spectra, especially those recorded with high spectral resolution, can differ substantially from predictions, especially for spectra produced at collision velocities equal to or lower than those found in thermal plasmas or produced with neutral gases other than atomic hydrogen. Puzzling discrepancies can be noted, such as enhanced emission from an upper level with the 'wrong' principal quantum number. Even more puzzling is a recent experiment in which two, co-mixed bare ion species of similar atomic number produce very different Lyman series emission upon charge exchange with a given neutral gas, defying both theoretical predictions and empirical scaling. Laboratory measurements have also shown that some of the characteristic features of charge exchange can be reproduced by radiative electron capture, i.e., by capture of a continuum

  10. Dynamics of the fully stripped ion-hydrogen atom charge exchange process in dense quantum plasmas

    SciTech Connect

    Zhang, Ling-yu; Wan, Jiang-feng; Zhao, Xiao-ying; Xiao, Guo-qing; Duan, Wen-shan; Qi, Xin; Yang, Lei

    2014-09-15

    The plasma screening effects of dense quantum plasmas on charge exchange processes of a fully stripped ion colliding with a hydrogen atom are studied by the classical trajectory Monte Carlo method. The inter-particle interactions are described by the exponential cosine-screened Coulomb potentials. It is found that in weak screening conditions, cross sections increase with the increase of the ionic charge Z. However, in strong screening conditions, the dependence of cross sections on the ionic charge is related to the incident particle energy. At high energies, cross sections show a linear increase with the increase of Z, whereas at low energies, cross sections for Z≥4 become approximately the same. The He{sup 2+} and C{sup 6+} impacting charge exchange cross sections in dense quantum plasmas are also compared with those in weakly coupled plasmas. The interactions are described by the static screened Coulomb potential. It is found that for both He{sup 2+} and C{sup 6+}, the oscillatory screening effects of dense quantum plasmas are almost negligible in weak screening conditions. However, in strong screening conditions, the oscillatory screening effects enhance the screening effects of dense quantum plasmas, and the enhancement becomes more and more significant with the increase of the screening parameter and the ionic charge.

  11. Poynting flux in the neighbourhood of a point charge in arbitrary motion and radiative power losses

    NASA Astrophysics Data System (ADS)

    Singal, Ashok K.

    2016-07-01

    We examine the electromagnetic fields in the neighbourhood of a ‘point charge’ in arbitrary motion and thereby determine the Poynting flux across a spherical surface of vanishingly small radius surrounding the charge. We show that the radiative power losses from a point charge turn out to be proportional to the scalar product of the instantaneous velocity and the first time-derivative of the acceleration of the charge. This may seem to be discordant with the familiar Larmor formula where the instantaneous power radiated from a charge is proportional to the square of acceleration. However, it seems that the root cause of the discrepancy actually lies in Larmor’s formula, which is derived using the acceleration fields but without due consideration for the Poynting flux associated with the velocity-dependent self-fields ‘co-moving’ with the charge. Further, while deriving Larmor’s formula, one equates the Poynting flux through a surface at some later time to the radiation loss by the enclosed charge at the retarded time. Poynting’s theorem, on the other hand, relates the outgoing radiation flux from a closed surface to the rate of energy decrease within the enclosed volume, all calculated for the same given instant only. Here we explicitly show the absence of any Poynting flux in the neighbourhood of an instantly stationary point charge, implying no radiative losses from such a charge, which is in complete conformity with energy conservation. We further show how Larmor’s formula is still able to serve our purpose in the vast majority of cases. It is further shown that Larmor’s formula in general violates momentum conservation and, in the case of synchrotron radiation, leads to a potentially incorrect conclusion about the pitch angle changes of the radiating charges, and that only the radiation reaction formula yields a correct result, consistent with special relativity.

  12. Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, B.

    2002-01-01

    The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory (LLNL) to study X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in existing experimental and theoretical understanding of this atomic physics process, and are needed to explain all or part of the observed X-ray emission from the soft X-ray background, stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae. Progress made during the first year of the grant is described, as is work planned for the second year.

  13. ({sup 18}O,{sup 18}Ne) double charge-exchange with MAGNEX

    SciTech Connect

    Bondí, M.; Cappuzzello, F.; Nicolosi, D.; Tropea, S.; Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; De Napoli, M.; Foti, A.

    2014-05-09

    An experimental study concerning Double Gamow-Teller (DGT) modes in ({sup 18}O,{sup 18}Ne) Double Charge-Exchange reactions has been very recently performed at INFN-LNS laboratory in Catania. The experiment was performed using a {sup 40}Ca solid target and a {sup 18}O Cyclotron beam at 270 MeV incident energy. Charged ejectiles produced in the reaction were momentum analyzed and identified by MAGNEX spectrometer at very forward angles. Preliminary results are presented in the present paper.

  14. An electron energy-loss study of picene and chrysene based charge transfer salts

    NASA Astrophysics Data System (ADS)

    Müller, Eric; Mahns, Benjamin; Büchner, Bernd; Knupfer, Martin

    2015-05-01

    The electronic excitation spectra of charge transfer compounds built from the hydrocarbons picene and chrysene, and the strong electron acceptors F4TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) and TCNQ (7,7,8,8-tetracyanoquinodimethan) have been investigated using electron energy-loss spectroscopy. The corresponding charge transfer compounds have been prepared by co-evaporation of the pristine constituents. We demonstrate that all investigated combinations support charge transfer, which results in new electronic excitation features at low energy. This might represent a way to synthesize low band gap organic semiconductors.

  15. An electron energy-loss study of picene and chrysene based charge transfer salts.

    PubMed

    Müller, Eric; Mahns, Benjamin; Büchner, Bernd; Knupfer, Martin

    2015-05-14

    The electronic excitation spectra of charge transfer compounds built from the hydrocarbons picene and chrysene, and the strong electron acceptors F4TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) and TCNQ (7,7,8,8-tetracyanoquinodimethan) have been investigated using electron energy-loss spectroscopy. The corresponding charge transfer compounds have been prepared by co-evaporation of the pristine constituents. We demonstrate that all investigated combinations support charge transfer, which results in new electronic excitation features at low energy. This might represent a way to synthesize low band gap organic semiconductors.

  16. An electron energy-loss study of picene and chrysene based charge transfer salts

    SciTech Connect

    Müller, Eric; Mahns, Benjamin; Büchner, Bernd; Knupfer, Martin

    2015-05-14

    The electronic excitation spectra of charge transfer compounds built from the hydrocarbons picene and chrysene, and the strong electron acceptors F{sub 4}TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) and TCNQ (7,7,8,8-tetracyanoquinodimethan) have been investigated using electron energy-loss spectroscopy. The corresponding charge transfer compounds have been prepared by co-evaporation of the pristine constituents. We demonstrate that all investigated combinations support charge transfer, which results in new electronic excitation features at low energy. This might represent a way to synthesize low band gap organic semiconductors.

  17. 26 CFR 1.988-3 - Character of exchange gain or loss.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 10 2010-04-01 2010-04-01 false Character of exchange gain or loss. 1.988-3 Section 1.988-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME... transactions entered into after March 17, 1992. (6) Effective date. Except as otherwise provided,...

  18. Charge exchange contamination of CRIT-II barium CIV experiment. [critical ionization velocity in ionosphere

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.; Meyerott, R. E.; Rairden, R. L.

    1991-01-01

    Experiments have been recently performed which attempted to confirm critical ionization velocity (CIV) ionization by deploying chemicals at high velocity in the ionosphere. Specifically, the CRIT-II rocket performed a barium release in the ionosphere, where observations of Ba(+) resonant emissions following the release are believed to have resulted from the CIV process. Calculations are presented which suggest a significant fraction (if not all) of the Ba(+) observed likely resulted from charge exchange with the thermosphere ions and not through CIV processes. The results presented here are pertinent to other CIV experiments performed in the ionosphere. It is recommended that laboratory measurements should be made of the charge exchange cross section between O(+) and Ba as well as other metal vapors used in CIV experiments.

  19. Influence of resonant charge exchange on the viscosity of partially ionized plasma in a magnetic field

    SciTech Connect

    Zhdanov, V. M. Stepanenko, A. A.

    2013-12-15

    The influence of resonant charge exchange for ion-atom interaction on the viscosity of partially ionized plasma embedded in the magnetic field is investigated. The general system of equations used to derive the viscosity coefficients for an arbitrary plasma component in the 21-moment approximation of Grad’s method is presented. The expressions for the coefficients of total and partial viscosities of a multicomponent partially ionized plasma in the magnetic field are obtained. As an example, the coefficients of the parallel and transverse viscosities for the ionic and neutral components of the partially ionized hydrogen plasma are calculated. It is shown that the account for resonant charge exchange can lead to a substantial change of the parallel and transverse viscosity of the plasma components in the region of low degrees of ionization on the order of 0.1.

  20. ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, Timothy J.; Travnicek, P.

    2012-01-01

    We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction.

  1. Solar wind/local interstellar medium interaction including charge exchange with neural hydrogen

    NASA Technical Reports Server (NTRS)

    Pauls, H. Louis; Zank, Gary P.

    1995-01-01

    We present results from a hydrodynamic model of the interaction of the solar wind with the local interstellar medium (LISM), self-consistently taking into account the effects of charge exchange between the plasma component and the interstellar neutrals. The simulation is fully time dependent, and is carried out in two or three dimensions, depending on whether the helio-latitudinal dependence of the solar wind speed and number density (both giving rise to three dimensional effects) are included. As a first approximation it is assumed that the neutral component of the flow can be described by a single, isotropic fluid. Clearly, this is not the actual situation, since charge exchange with the supersonic solar wind plasma in the region of the nose results in a 'second' neutral fluid propagating in the opposite direction as that of the LISM neutrals.

  2. Competition between charge exchange and chemical reaction - The D2/+/ + H system

    NASA Technical Reports Server (NTRS)

    Preston, R. K.; Cross, R. J., Jr.

    1973-01-01

    Study of the special features of molecular charge exchange and its competition with chemical reaction in the case of the D2(+) + H system. The trajectory surface hopping (TSH) model proposed by Tully and Preston (1971) is used to study this competition for a number of reactions involving the above system. The diatomics-in-molecules zero-overlap approximation is used to calculate the three adiabatic surfaces - one triplet and two singlet - which are needed to describe this system. One of the significant results of this study is that the chemical reaction and charge exchange are strongly coupled. It is also found that the number of trajectories passing into the chemical regions of the three surfaces depends very strongly on the surface crossings.-

  3. POLARIZATION OF THE CHARGE-EXCHANGE X-RAYS INDUCED IN THE HELIOSPHERE

    SciTech Connect

    Gacesa, M.; Kharchenko, V.; Mueller, H.-R.; Cote, R.

    2011-05-10

    We report results of a theoretical investigation of polarization of the X-ray emissions induced in charge-exchange collisions of fully stripped solar wind (SW) ions C{sup 6+} and O{sup 8+} with the heliospheric hydrogen atoms. The polarization of X-ray emissions has been computed for line-of-sight observations within the ecliptic plane as a function of SW ion velocities, including a range of velocities corresponding to the slow and fast SW, and coronal mass ejections. To determine the variability of polarization of heliospheric X-ray emissions, the polarization has been computed for solar minimum conditions with self-consistent parameters of the SW plasma and heliospheric gas and compared with the polarization calculated for an averaged solar activity. We predict the polarization of charge-exchange X-rays to be between 3% and 8%, depending on the line-of-sight geometry, SW ion velocity, and the selected emission lines.

  4. Modulation of terrestrial ion escape flux composition /by low-altitude acceleration and charge exchange chemistry/

    NASA Technical Reports Server (NTRS)

    Moore, T. E.

    1980-01-01

    Motivated by recent observations of highly variable hot plasma composition in the magnetosphere, control of the ionospheric escape flux composition by low-altitude particle dynamics and ion chemistry has been investigated for an e(-), H(+), O(+) ionosphere. It is found that the fraction of the steady state escape flux which is O(+) can be controlled very sensitively by the occurrence of parallel or transverse ion acceleration at altitudes below the altitude where the neutral oxygen density falls rapidly below the neutral hydrogen density and the ionospheric source of O(+) tends to be rapidly converted by charge exchange to H(+). The acceleration is required both to overcome the gravitational confinement of O(+) and to violate charge exchange equilibrium so that the neutral hydrogen atmosphere appears 'optically' thin to escaping O(+). Constraints are placed on the acceleration processes, and it is shown that O(+) escape is facilitated by observed ionospheric responses to magnetic activity.

  5. Charge-exchange erosion studies of accelerator grids in ion thrusters

    NASA Technical Reports Server (NTRS)

    Peng, Xiaohang; Ruyten, Wilhelmus M.; Keefer, Dennis

    1993-01-01

    A particle simulation model is developed to study the charge-exchange grid erosion in ion thrusters for both ground-based and space-based operations. Because the neutral gas downstream from the accelerator grid is different for space and ground operation conditions, the charge-exchange erosion processes are also different. Based on an assumption of now electric potential hill downstream from the ion thruster, the calculations show that the accelerator grid erosion rate for space-based operating conditions should be significantly less than experimentally observed erosion rates from the ground-based tests conducted at NASA Lewis Research Center (LeRC) and NASA Jet Propulsion Laboratory (JPL). To resolve this erosion issue completely, we believe that it is necessary to accurately measure the entire electric potential field downstream from the thruster.

  6. Charge exchange processes in He+/Cu scattering at low energy

    NASA Astrophysics Data System (ADS)

    Khalal-Kouache, K.; Bruckner, B.; Roth, D.; Goebl, D.; Bauer, P.

    2016-09-01

    In this paper we present results on charge exchange of He+ ions at a polycrystalline Cu surface. Monte Carlo simulations were used to calculate the trajectories of projectiles scattered by an angle Θ = 136 ° . By including Auger neutralization and charge exchange in close collisions, energy spectra of the scattered ions as well as ion fraction values were calculated for primary energies in the range 0.5-5 keV and compared to experimental results. In the simulations, the Auger neutralization rate Γ and the probabilities of resonant neutralization (PRN) and reionization (PRI) are treated as free parameters. Using well accepted values from literature for these quantities very good agreement between simulations and experimental data was achieved.

  7. Charge Exchange and Ablation Rates of a Titanium Wire Plasma Corona

    SciTech Connect

    Terry, Robert E.

    2009-01-21

    Wire ablation rates are important features in any examination of precursors or transparent mode implosions of wire arrays. When ion temperatures in a Ti wire plasma corona exceed a few eV, the process of resonant charge exchange competes with elastic scattering. Ions pushed into the corona from an anode bias wire array can be expected to drive a fast neutral wind into the surrounding volume, while a cathode bias wire array would not show the strong neutral wind.

  8. Measurement of pion double charge exchange on carbon-13, carbon-14, magnesium-26, and iron-56

    SciTech Connect

    Seidl, P.A.

    1985-02-01

    Cross sections for the /sup 13,14/C,/sup 26/Mg,/sup 56/Fe(..pi../sup +/,..pi../sup -/)/sup 13,14/O,/sup 26/Si,/sup 56/Ni reactions were measured with the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility for 120 less than or equal to T/sub ..pi../ less than or equal to 292 MeV and 0 less than or equal to theta less than or equal to 50. The double isobaric analog states (DIAS) are of primary interest. In addition, cross sections for transitions to /sup 14/O(0/sup +/, 5.92 MeV), /sup 14/O(2/sup +/, 7.77 MeV), /sup 56/Ni(gs), /sup 13/O(gs), and /sup 13/O(4.21 MeV) are presented. The /sup 13/O(4.21 MeV) state is postulated to have J/sup ..pi../ = 1/2/sup -/. The data are compared to previously measured double-charge-exchange cross sections on other nuclei, and the systematics of double charge exchange on T greater than or equal to 1 target nuclei leading to the DIAS are studied. Near the ..delta../sub 33/ resonance, cross sections for the DIAS transitions are in disagreement with calculations in which the reaction is treated as sequential charge exchange through the free pion-nucleon amplitude, while for T/sub ..pi../ > 200 MeV the anomalous features of the 164 MeV data are not apparent. This is evidence for significant higher order contributions to the double-charge-exchange amplitude near the reasonable energy. Two theoretical approaches that include two nucleon processes are applied to the DIAS data. 64 references.

  9. Helium escape from the Earth's atmosphere - The charge exchange mechanism revisited

    NASA Technical Reports Server (NTRS)

    Lie-Svendsen, O.; Rees, M. H.; Stamnes, K.

    1992-01-01

    We have studied the escape of neutral helium from the terrestrial atmosphere through exothermic charge exchange reactions between He(+) ions and the major atmospheric constituents N2, O2 and O. Elastic collisions with the neutral background particles were treated quantitatively using a recently developed kinetic theory approach. An interhemispheric plasma transport model was employed to provide a global distribution of He(+) ions as a function of altitude, latitude and local solar time and for different levels of solar ionization. Combining these ion densities with neutral densities from an MSIS model and best estimates for the reaction rate coefficients of the charge exchange reactions, we computed the global distribution of the neutral He escape flux. The escape rates show large diurnal and latitudinal variations, while the global average does not vary by more than a factor of three over a solar cycle. We find that this escape mechanism is potentially important for the overall balance of helium in the Earth's atmosphere. However, more accurate values for the reaction rate coefficients of the charge exchange reactions are required to make a definitive assessment of its importance.

  10. Coherent control of charge exchange in strong-field dissociation of LiF

    NASA Astrophysics Data System (ADS)

    Armstrong, Greg; Esry, Brett

    2016-05-01

    The alkali-metal-halides family of molecules are useful prototypes in the study of laser-assisted charge exchange. Typically these molecules possess a field-free crossing between the ionic and covalent diabatic Born-Oppenheimer potential curves, leading to Li+ + F- and Li + F in LiF. These channels are energetically well-separated from higher-lying potentials, and may be easily distinguished experimentally. Moreover, charge exchange involves non-adiabatic transitions between the ionic and covalent channels, thereby allowing the investigation of physics beyond the Born-Oppenheimer approximation. The focus of this work is to control the preference between ionic and covalent dissociative products. We solve the time-dependent Schrödinger equation for the nuclear motion in full dimensionality, and investigate a pump-probe scheme for charge-exchange control. The degree of control is investigated by calculating the kinetic-energy release spectrum as a function of pump-probe delay for the ionic and covalent fragments. This work is supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  11. Modeling the Hydrogen-Proton Charge-Exchange Process in Global Heliospheric Simulations

    NASA Astrophysics Data System (ADS)

    DeStefano, A.; Heerikhuisen, J.

    2015-12-01

    The environment surrounding our Solar System has a vast and dynamic structure. As the Sun rounds the Milky Way galaxy, interstellar dust and gas interact with the Sun's outflow of solar wind. A bubble of hot plasma forms around the Sun due to this interaction, called the heliosphere. In order to understand the structure of the heliosphere, observations and simulations must work in tandem. Within the past decade or so, 3D models of the heliosphere have been developed exhibiting non- symmmetric as well as predicting structures such as the hydrogen wall and the IBEX ribbon. In this poster we explore new ways to compute charge-exchange source terms. The charge-exchange process is the coupling mechanism between the MHD and kinetic theories. The understanding of this process is crucial in order to make valuable predictions. Energy dependant cross section terms will aid in settling non-linear affects coupling the intestellar and solar particles. Through these new ways of computing source terms, resolving fine structures in the plasma in the heliopause may be possible. In addition, other non-trivial situations, such as charge-exchange mediated shocks, may be addressed.

  12. Charge exchange in a planetary corona - Its effect on the distribution and escape of hydrogen

    NASA Technical Reports Server (NTRS)

    Chamberlain, J. W.

    1977-01-01

    The theory for a spherical collisionless planetary corona is extended to include charge-exchange collisions between H(+) and H, which are assumed to constitute intermingled gases with different kinetic temperatures. The treatment is based on the conventional concept of a critical level (or exobase) above which the only collisions considered in the Boltzmann equation are those that resonantly exchange charge. Although the geometry treated is an oversimplification for a real planet, numerical examples are given for an idealized earth and Venus. For earth, an ion temperature of 4 times the neutral temperature, an ion density at the exobase of 14,000 per cu cm, and a plasmapause at 1.5 earth radii will raise the escape flux of H by a factor of 6. The total H above the exobase is changed by less than 1%. For Venus, conditions are examined that would account for the peculiar H distribution observed from Mariner 5. The plasma conditions required are not obviously outrageous by terrestrial standards, but the Mariner 5 ionosphere measurements did not show a high plasmapause at, say, 1.25 or 1.5 planetary radii, a fact that might argue against a charge-exchange model.

  13. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    DOE PAGES

    Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G.

    2015-10-28

    In this study, optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recoverymore » time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.« less

  14. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    SciTech Connect

    Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G.

    2015-10-28

    In this study, optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.

  15. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    PubMed Central

    Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G.

    2015-01-01

    Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation. PMID:26508587

  16. Charge-exchange measurements of beam ion thermalization in MHD-quiescent plasmas in the Poloidal Divertor Experiment

    SciTech Connect

    Kaita, R.; Goldston, R.J.; Beiersdorfer, P.; Herndon, D.L.; Kaye, S.M.; Kugel, H.W.; McCann, R.T.; McCune, D.C.; Meyerhofer, D.D.; Towner, H.H.

    1984-10-01

    The horizontally scanning, multiangle charge-exchange analyzer on the Poloidal Divertor Experiment (PDX) was used to study the beam ion slowing-down process with high-power perpendicular injection. Measurements were made over a wide range in toroidal field (8 kG < B(T) < 22 kG), plasma current (200 kA < I(p) < 500 kA), and beam power (1 MW < P/sub B/ < 7 MW). In MHD-quiescent plasmas, good agreement is found between the measured slowing-down spectra and theoretical predictions as a function of both angle and energy. Classes of prompt orbit losses are observed with both co- and counter-injection which have been understood and applied to plasma diagnostics. The effects of MHD activity on fast ion thermalization will be the subject of a companion paper.

  17. Modeling of protein-anion exchange resin interaction for the human growth hormone charge variants.

    PubMed

    Lapelosa, Mauro; Patapoff, Thomas W; Zarraga, Isidro E

    2015-12-01

    Modeling ion exchange chromatography (IEC) behavior has generated significant interest because of the wide use of IEC as an analytical technique as well as a preparative protein purification process; indeed there is a need for better understanding of what drives the unique behavior of protein charge variants. We hypothesize that a complex protein molecule, which contains both hydrophobic and charged moieties, would interact strongly with an in silico designed resin through charged electrostatic patches on the surface of the protein. In the present work, variants of recombinant human growth hormone that mimic naturally-occurring deamidation products were produced and characterized in silico. The study included these four variants: rhGH, N149D, N152D, and N149D/N152D. Poisson-Boltzmann calculations were used to determine surface electrostatic potential. Metropolis Monte Carlo simulations were carried out with the resulting variants to simulate IEC systems, examining the free energy of the interaction of the protein with an in silico anion exchange column represented by polylysine polypeptide. The results show that the charge variants have different average binding energies and the free energy of interaction can be used to predict the retention time for the different variants.

  18. Laboratory Measurements of Solar-Wind/Comet X-Ray Emission and Charge Exchange Cross Sections

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Cadez, I.; Greenwood, J. B.; Mawhorter, R. J.; Smith, S. J.; Lozano, J.

    2002-01-01

    The detection of X-rays from comets such as Hyakutake, Hale-Bopp, d Arrest, and Linear as they approach the Sun has been unexpected and exciting. This phenomenon, moreover, should be quite general, occurring wherever a fast solar or stellar wind interacts with neutrals in a comet, a planetary atmosphere, or a circumstellar cloud. The process is, O(+8) + H2O --> O(+7*) + H2O(+), where the excited O(+7*) ions are the source of the X-ray emissions. Detailed modeling has been carried out of X-ray emissions in charge-transfer collisions of heavy solar-wind Highly Charged Ions (HCIs) and interstellar/interplanetary neutral clouds. In the interplanetary medium the solar wind ions, including protons, can charge exchange with interstellar H and He. This can give rise to a soft X-ray background that could be correlated with the long-term enhancements seen in the low-energy X-ray spectrum of ROSAT. Approximately 40% of the soft X-ray background detected by Exosat, ROSAT, Chandra, etc. is due to Charge Exchange (CXE): our whole heliosphere is glowing in the soft X-ray due to CXE.

  19. Unresolved puzzles in the x-ray emission produced by charge exchange measured on electron beam ion traps

    SciTech Connect

    Beiersdorfer, P.; Brown, G. V.; Clementson, J.; Kilbourne, C. A.; Kelley, R. L.; Leutenegger, M. A.; Porter, F. S.; Schweikhard, L.

    2013-04-19

    Charge exchange recombination, the transfer of one or more electrons from an atomic or molecular system to a positive ion, is a common phenomenon affecting laboratory and astrophysical plasmas. Controlled studies of this process in electron beam ion traps during the past one and a half decades have produced multiple observations that are difficult to explain with available spectral models. Some of the most recent observations are so puzzling that they bring in doubt the existence of a coherent predictive capability for line formation by charge exchange, making investigations of charge exchange a fertile ground for continued measurements and theoretical development.

  20. Polarization correction in the theory of energy losses by charged particles

    SciTech Connect

    Makarov, D. N. Matveev, V. I.

    2015-05-15

    A method for finding the polarization (Barkas) correction in the theory of energy losses by charged particles in collisions with multielectron atoms is proposed. The Barkas correction is presented in a simple analytical form. We make comparisons with experimental data and show that applying the Barkas correction improves the agreement between theory and experiment.

  1. The impact of hot charge carrier mobility on photocurrent losses in polymer-based solar cells.

    PubMed

    Philippa, Bronson; Stolterfoht, Martin; Burn, Paul L; Juška, Gytis; Meredith, Paul; White, Ronald D; Pivrikas, Almantas

    2014-07-22

    A typical signature of charge extraction in disordered organic systems is dispersive transport, which implies a distribution of charge carrier mobilities that negatively impact on device performance. Dispersive transport has been commonly understood to originate from a time-dependent mobility of hot charge carriers that reduces as excess energy is lost during relaxation in the density of states. In contrast, we show via photon energy, electric field and film thickness independence of carrier mobilities that the dispersive photocurrent in organic solar cells originates not from the loss of excess energy during hot carrier thermalization, but rather from the loss of carrier density to trap states during transport. Our results emphasize that further efforts should be directed to minimizing the density of trap states, rather than controlling energetic relaxation of hot carriers within the density of states.

  2. Observed Limits on Charge Exchange Contributions to the Diffuse X-Ray Background

    NASA Technical Reports Server (NTRS)

    Crowder, S. G.; Barger, K. A.; Brandl, D. E.; Eckart, M. E.; Galeazzi, M.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Pfendner, C. G.; Porter, F. S.; Rocks, L.; Szymkowiak, A. E.; Teplin, I. M.

    2012-01-01

    We present a high-resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for an approximately 1 sr region of the sky centered at l = 90 degrees b = +60 degrees using a 36 pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum s observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568 (sup +2 (sub -3) eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV and for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex. The dominance of thermal emission is consistent with much of the high-latitude O VII emission originating in 2-3 x 10(exp 6) K gas in the Galactic halo. On the other hand, the observed ratio of C VI Lygamma to Lyalpha is 0.3 plus or minus 0.2. The expected ratios are 0.04 for thermal emission and 0.24 for charge exchange, indicating that charge exchange must contribute strongly to this line and therefore potentially to the rest of the ROSAT R12 band usually associated with 10(sup 6) K emission from the Local Hot Bubble. The limited statistics of this experiment and systematic uncertainties due to the contamination require only greater than 32% thermal emission for O VII and greater than 20% from charge exchange for C VI at the 90% confidence level. An experimental gold coating on the silicon substrate of the array greatly reduced extraneous signals induced on nearby pixels from cosmic rays passing through the substrate, reducing the triggered event rate by a factor of 15 from a previous flight of the instrument.

  3. Trace adsorption of positively charged proteins onto Sepharose FF and Sepharose FF-based anion exchangers.

    PubMed

    Yu, Lin-Ling; Sun, Yan

    2012-08-31

    Agarose-based matrices have been widely used in ion exchange chromatography (IEC). We have herein observed that positively charged proteins (lysozyme and cytochrome c) are adsorbed on the agarose-based anion-exchangers (Q and DEAE Sepharose FF gels) in a capacity of 10-40 μg/mL. In contrast, negatively charged protein (bovine serum albumin) is not adsorbed to Sepharose FF and SP Sepharose FF gels. Elemental analysis of the gel indicated that the residual anionic sulfate groups in agarose would have worked as the cation exchange groups for the positively charged proteins. The trace adsorption behavior of lysozyme onto Sepharose FF and Sepharose FF-based anion exchangers was studied and the effects of NaCl concentration and cation group density on the adsorption were examined for better understanding of the trace adsorption in chromatographic processes. At NaCl concentrations less than 0.05 mol/L, which is the normal adsorption condition in IEC, the trace adsorption kept at a high level, so this trace adsorption cannot be avoided in the ionic strength range of routine IEC operations. Grafting poly(ethylenimine) (PEI) chain of 60 kDa to a cation group density of 700 mmol/L could reduce the adsorption capacity to about 20 μg/mL, but further reduction was not possible by increasing the cation group density to 1200 mmol/L. Therefore, attentions need to be paid to the phenomenon in protein purification practice using agarose-based matrices. The research is expected to call attentions to the trace adsorption on agarose-based matrices and to the importance in the selection of the suitable solid matrices in the production of high-purity protein products in large-scale bioprocesses.

  4. Oscillating-flow loss test results in rectangular heat exchanger passages

    NASA Technical Reports Server (NTRS)

    Wood, J. Gary

    1991-01-01

    Test results of oscillating flow losses in rectangular heat exchanger passages of various aspect ratios are given. This work was performed in support of the design of a free-piston Stirling engine (FPSE) for a dynamic space power conversion system. Oscillating flow loss testing was performed using an oscillating flow rig, which was based on a variable stroke and variable frequency linear drive motor. Tests were run over a range of oscillating flow parameters encompassing the flow regimes of the proposed engine design. Test results are presented in both tabular and graphical form and are compared against analytical predictions.

  5. Reynolds number effects on pressure loss and turbulence characteristics of four tube-bundle heat exchangers

    NASA Technical Reports Server (NTRS)

    Gentry, L., Jr.; Gentry, C. L., Jr.

    1983-01-01

    The aerodynamic characteristics of pressure loss and turbulence on four tube-bundle configurations representing heat-exchanger geometries with nominally the same heat capacity were measured as a function of Reynolds numbers from about 4000 to 400,000 based on tube hydraulic diameter. Two configurations had elliptical tubes, the other two had round tubes, and all four had plate fins. The elliptical-tube configurations had lower pressure loss and turbulence characteristics than the round-tube configurations over the entire Reynolds number range.

  6. A comprehensive model of ion diffusion and charge exchange in the cold Io torus

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.; Moreno, M. A.

    1988-01-01

    A comprehensive analytic model of radial diffusion in the cold Io torus is developed. The model involves a generalized molecular cloud theory of SO2 and its dissociation fragments SO, O2, S, and O, which are formed at a relatively large rate by solar UV photodissociation of SO2. The key component of the new theory is SO, which can react with S(+) through a near-resonant charge exchange process that is exothermic. This provides a mechanism for the rapid depletion of singly ionized sulfur in the cold torus and can account for the large decrease in the total flux tube content inward of Io's orbit. The model is used to demonstrate quantitatively the effects of radial diffusion in a charge exchange environment that acts as a combined source and sink for ions in various charge states. A detailed quantitative explanation for the O(2+) component of the cold torus is given, and insight is derived into the workings of the so-called plasma 'ribbon'.

  7. Development of two-grating spectrometer for the charge exchange spectroscopy system on KSTAR

    NASA Astrophysics Data System (ADS)

    Lee, Hyungho; Song, Eun-ji; Park, Young-dong; Oh, Soo-ghee; Ko, Won-Ha

    2011-06-01

    The charge exchange spectroscopy (CES) system on Korea Superconducting Tokamak Advanced Research (KSTAR) was installed last year and had been applied to measure the C VI ion temperature and rotation velocity profiles. The ion temperature and rotation velocity profiles had been estimated from the C VI 5290.5 Å (n = 8-7) charge-exchange spectrum signal measured by a Czerny-Turner type spectrometer and a thinned back-illuminated charge coupled device (CCD) camera. However, the Czerny-Turner type spectrometer used for the KSTAR CES system showed so low signal to noise ratio for KSTAR plasmas in the 2010 experimental campaign that the time resolution of the CES system had been limited to 100 ms due to the increased exposure time of the attached CCD camera. Then, new two-grating spectrometer had been developed in order to improve the time resolution of the CES system. The spectrometer consists of two gratings (1200 g/mm and 1800 g/mm each) with additive configuration, concave mirrors (f = 50 cm), and a cylindrical lens (f = 50 cm). The time resolution of the CES system increases by a factor of 2-4 with the two-grating spectrometer. The C VI ion temperature and rotation velocity profiles obtained by the two-grating spectrometer are compared to those by Czerny-Turner type spectrometer in this paper.

  8. Development of two-grating spectrometer for the charge exchange spectroscopy system on KSTAR

    SciTech Connect

    Lee, Hyungho; Song, Eun-ji; Oh, Soo-ghee; Park, Young-dong; Ko, Won-Ha

    2011-06-15

    The charge exchange spectroscopy (CES) system on Korea Superconducting Tokamak Advanced Research (KSTAR) was installed last year and had been applied to measure the C VI ion temperature and rotation velocity profiles. The ion temperature and rotation velocity profiles had been estimated from the C VI 5290.5 A (n = 8-7) charge-exchange spectrum signal measured by a Czerny-Turner type spectrometer and a thinned back-illuminated charge coupled device (CCD) camera. However, the Czerny-Turner type spectrometer used for the KSTAR CES system showed so low signal to noise ratio for KSTAR plasmas in the 2010 experimental campaign that the time resolution of the CES system had been limited to 100 ms due to the increased exposure time of the attached CCD camera. Then, new two-grating spectrometer had been developed in order to improve the time resolution of the CES system. The spectrometer consists of two gratings (1200 g/mm and 1800 g/mm each) with additive configuration, concave mirrors (f = 50 cm), and a cylindrical lens (f = 50 cm). The time resolution of the CES system increases by a factor of 2-4 with the two-grating spectrometer. The C VI ion temperature and rotation velocity profiles obtained by the two-grating spectrometer are compared to those by Czerny-Turner type spectrometer in this paper.

  9. Development of two-grating spectrometer for the charge exchange spectroscopy system on KSTAR.

    PubMed

    Lee, Hyungho; Song, Eun-ji; Park, Young-dong; Oh, Soo-ghee; Ko, Won-Ha

    2011-06-01

    The charge exchange spectroscopy (CES) system on Korea Superconducting Tokamak Advanced Research (KSTAR) was installed last year and had been applied to measure the C VI ion temperature and rotation velocity profiles. The ion temperature and rotation velocity profiles had been estimated from the C VI 5290.5 Å (n = 8-7) charge-exchange spectrum signal measured by a Czerny-Turner type spectrometer and a thinned back-illuminated charge coupled device (CCD) camera. However, the Czerny-Turner type spectrometer used for the KSTAR CES system showed so low signal to noise ratio for KSTAR plasmas in the 2010 experimental campaign that the time resolution of the CES system had been limited to 100 ms due to the increased exposure time of the attached CCD camera. Then, new two-grating spectrometer had been developed in order to improve the time resolution of the CES system. The spectrometer consists of two gratings (1200 g/mm and 1800 g/mm each) with additive configuration, concave mirrors (f = 50 cm), and a cylindrical lens (f = 50 cm). The time resolution of the CES system increases by a factor of 2-4 with the two-grating spectrometer. The C VI ion temperature and rotation velocity profiles obtained by the two-grating spectrometer are compared to those by Czerny-Turner type spectrometer in this paper.

  10. Charge exchange collisions of slow C6 + with atomic and molecular H

    NASA Astrophysics Data System (ADS)

    Saha, Bidhan C.; Guevara, Nicolais L.; Sabin, John R.; Deumens, Erik; Öhrn, Yngve

    2016-04-01

    Charge exchange in collisions of C6+ ions with H and H2 is investigated theoretically at projectile energies 0.1 < E < 10 keV/amu, using electron nuclear dynamics (END) - a semi-classical approximation which not only includes electron translation factors for avoiding spurious couplings but also employs full dynamical trajectories to treat nuclear motions. Both the total and partial cross sections are reported for the collision of C6+ ions with atomic and molecular hydrogen. A comparison with other theoretical and experimental results shows, in general good agreement except at very low energy, considered here. For H2, the one- and two-electron charge exchange cross sections are calculated and compared with other theoretical and experimental results. Small but non-negligible isotope effects are found at the lowest energy studied in the charge transfer of C6+ with H. In low energy region, it is observed that H2 has larger isotope effects than H atom due to the polarizability effect which is larger than the mass effect.

  11. Charge deposition dependence and energy loss of electrons transmitted through insulating PET nanocapillaries

    NASA Astrophysics Data System (ADS)

    Keerthisinghe, D.; Dassanayake, B. S.; Wickramarachchi, S. J.; Stolterfoht, N.; Tanis, J. A.

    2013-12-01

    The charge deposition dependence and energy loss in the transmission of electrons through insulating polyethylene terephthalate (PET) were studied for incident energies of 500 and 800 eV. Charge evolution at the sample tilt angles ψ = 0.0° and -1.7° was investigated. After an initial quiescent period transmission was observed and found to reach equilibrium rather quickly. Inelastic behavior of the transmitted electrons was observed during the initial transmission as well as after reaching equilibrium for ψ = -1.7° for both incident energies.

  12. Charge-exchange plasma environment for an ion drive spacecraft. [a model for describing mercury ion engines and its effect on spacecraft subsystems

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Carruth, M. R., Jr.

    1979-01-01

    The charge exchange plasma environment around a spacecraft that uses mercury ion thrusters for propulsion is described. The interactions between the plasma environment and the spacecraft are determined and a model which describes the propagation of the mercury charge exchange plasma is discussed. The model is extended to describe the flow of the molybdenum component of the charge exchange plasma. The uncertainties in the models for various conditions are discussed and current drain to the solar array, charge exchange plasma material deposition, and the effects of space plasma on the charge exchange plasma propagation are addressed.

  13. Ion exchange phase transitions in water-filled channels with charged walls.

    PubMed

    Zhang, J; Kamenev, A; Shklovskii, B I

    2006-05-01

    Ion transport through narrow water-filled channels is impeded by a high electrostatic barrier. The latter originates from the large ratio of the dielectric constants of the water and the surrounding media. We show that "doping," i.e., immobile charges attached to the walls of the channel, substantially reduces the barrier. This explains why most of the biological ion channels are "doped." We show that at rather generic conditions the channels may undergo ion exchange phase transitions (typically of the first order). Upon such a transition a finite latent concentration of ions may either enter or leave the channel, or be exchanged between the ions of different valences. We discuss possible implications of these transitions for the Ca-vs-Na selectivity of biological Ca channels. We also show that transport of divalent Ca ions is assisted by their fractionalization into two separate excitations.

  14. Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Nakajima, Hiroshi; Takakura, Satoru; Petre, Robert; Hewitt. John W.; Yamaguchi, Hiroya

    2011-01-01

    X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant s rim are depleted to approx.0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously "enhanced" abundances (up to approx. 1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the "enhanced" abundance regions commonly show a strong emission feature at approx.0.7 keV. This feature is likely a complex of He-like O K(gamma + delta + epsilon), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O K(alpha) appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently "enhanced" metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question. Subject headings: ISM: abundances ISM: individual objects (Cygnus Loop) ISM: supernova remnants X-rays: ISM atomic processes

  15. Correlation between charge transfer and exchange coupling in carbon-based magnetic materials

    SciTech Connect

    Nguyen, Anh Tuan; Nguyen, Van Thanh; Nguyen, Huy Sinh; Pham, Thi Tuan Anh; Do, Viet Thang; Dam, Hieu Chi

    2015-10-15

    Several forms of carbon-based magnetic materials, i.e. single radicals, radical dimers, and alternating stacks of radicals and diamagnetic molecules, have been investigated using density-functional theory with dispersion correction and full geometry optimization. Our calculated results demonstrate that the C{sub 31}H{sub 15} (R{sub 4}) radical has a spin of ½. However, in its [R{sub 4}]{sub 2} dimer structure, the net spin becomes zero due to antiferromagnetic spin-exchange between radicals. To avoid antiferromagnetic spin-exchange of identical face-to-face radicals, eight alternating stacks, R{sub 4}/D{sub 2m}/R{sub 4} (with m = 3-10), were designed. Our calculated results show that charge transfer (Δn) between R{sub 4} radicals and the diamagnetic molecule D{sub 2m} occurs with a mechanism of spin exchange (J) in stacks. The more electrons that transfer from R{sub 4} to D{sub 2m}, the stronger the ferromagnetic spin-exchange in stacks. In addition, our calculated results show that Δn can be tailored by adjusting the electron affinity (E{sub a}) of D{sub 2m}. The correlation between Δn, E{sub a}, m, and J is discussed. These results give some hints for the design of new ferromagnetic carbon-based materials.

  16. Neutrino nuclear responses for double beta decays and astro neutrinos by charge exchange reactions

    NASA Astrophysics Data System (ADS)

    Ejiri, Hiroyasu

    2014-09-01

    Neutrino nuclear responses are crucial for neutrino studies in nuclei. Charge exchange reactions (CER) are shown to be used to study charged current neutrino nuclear responses associated with double beta decays(DBD)and astro neutrino interactions. CERs to be used are high energy-resolution (He3 ,t) reactions at RCNP, photonuclear reactions via IAR at NewSUBARU and muon capture reactions at MUSIC RCNP and MLF J-PARC. The Gamow Teller (GT) strengths studied by CERs reproduce the observed 2 neutrino DBD matrix elements. The GT and spin dipole (SD) matrix elements are found to be reduced much due to the nucleon spin isospin correlations and the non-nucleonic (delta isobar) nuclear medium effects. Impacts of the reductions on the DBD matrix elements and astro neutrino interactions are discussed.

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

    SciTech Connect

    Hayes, A.C.

    1991-01-01

    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, pion double charge is found to act as an unusually sensitive probe of the properties of this exotic neutron rich nucleus. 9 refs., 2 figs.

  18. Production of Ca/sup -/ through sequential charge exchange with Li vapor

    SciTech Connect

    Alton, G.D.; Kvale, T.J.; Compton, R.N.; Pegg, D.J.; Thompson, J.S.

    1985-01-01

    The efficiencies for producing Ca/sup -/ through sequential charge exchange between Ca/sup +/ projectiles and Li vapor have been measured for the first time. The measurements were made over a projectile energy range of 20 to 100 keV under experimental conditions commensurate with tandem accelerator applications. Production efficiencies in terms of negative ion charge state fractions versus projectile energy, Li vapor cell temperature and Li target density were determined for negative ion formation within a detection window ..cap alpha.. of +-11 mrad. Within this range of angular divergence, the efficiency for production is observed to be an increasing function of the projectile energy even at the highest energies used during the measurements (100 keV). The results of these measurements as well as a description of the experimental apparatus and techniques utilized are presented. 19 refs., 5 figs.

  19. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    NASA Technical Reports Server (NTRS)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-01-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  20. Analysis of charge-exchange spectroscopy data by combining genetic and Gauss-Newton algorithms

    NASA Astrophysics Data System (ADS)

    Qian, Ma; Haoyi, Zuo; Yanling, Wei; Liang, Liu; Wenjin, Chen; Xiaoxue, He; Shirong, Luo

    2015-11-01

    The temperature and rotation velocity profile of ions in a tokamak are two characteristic parameters that reflect the plasma's behavior. Measurement of the two parameters relies on analyzing an active charge exchange spectroscopy diagnostic. However, a very challenging problem in such a diagnostic is the existence of interfering spectral lines, which can mislead the spectrum analysis process. This work proposes combining a genetic algorithm with the Gauss-Newton method (GAGN) to address this problem. Using this GAGN algorithm, we can effectively distinguish between the useful spectrum line and the interfering spectral lines within the spectroscopic output. The accuracy and stability of this algorithm are verified using both numerical simulation and actual measurements.

  1. Laser interferometric measurement of ion electrode shape and charge exchange erosion

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Mercer, Carolyn R.

    1991-01-01

    A projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thrustor. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3-D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid, nondestructive, digital data acquisition coupled with automated computer data processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes.

  2. Laser interferometric measurement of ion electrode shape and charge exchange erosion

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Mercer, Carolyn R.

    1991-01-01

    A novel projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thruster. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid nondestructive digital data acquisition coupled with automated computer data-processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes.

  3. Optical system design for the charge exchange spectroscopy of the Korea superconducting tokamak advanced research device

    NASA Astrophysics Data System (ADS)

    Oh, Seungtae; Ko, Won-Ha

    2011-04-01

    The collective optical design is described for the charge exchange spectroscopy (CES) of the Korea superconducting tokamak advanced research (KSTAR) device. The CES diagnostic measures the ion temperature of carbon and other impurities, in conjunction with the neutral heating beam in KSTAR. The visible light from the plasma is concentrated via collection optics and imaged onto quartz fibers. The collection optics in the system is the key component for the CES system. The final design is derived through four steps and its performance is examined in a simulation step. In this paper, the design details of the collective optical system for the KSTAR CES are discussed.

  4. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    NASA Astrophysics Data System (ADS)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-02-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  5. Helium measurements simulating alpha-particle diagnostics by the pellet charge exchange in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Ozaki, T.; Goncharov, P.; Veschev, E.; Sudo, S.; Tamura, N.; ,

    2008-03-01

    It is very important to investigate the confinement of α particle, which is produced by the nuclear reaction in ITER or fusion reactor. The pellet charge exchange measurement (PCX) is one of the most powerful methods because it can directly provide the profile of α particle energy spectra in plasma. In Large Helical Device (LHD), it is possible to confine the high energetic particle (helium) accelerated by using the ion cyclotron resonance heating (ICH). Therefore it is possible to perform the simulation experiment of α particle diagnostic in LHD.

  6. The observation of charge exchange of pions captured in several nuclei

    NASA Astrophysics Data System (ADS)

    Bassalleck, B.; Corriveau, F.; Hasinoff, M. D.; Marks, T.; Measday, D. F.; Poutissou, J.-M.; Salomon, M.

    1981-06-01

    We have measured for the first time the branching ratios of the charge exchange of stopped negative pions in targets of 6Li, Al, Ti, Cu, Nb and Pb. These branching ratios are of the order of 10 -6, about an order of magnitude smaller than the upper limit previously established. Using the branching ratio for radiative pion capture in 6Li to the ground state of 6He we obtain the Panofsky ratio in 6Li, P6 = (8.7 ± 2.3) × 10 -4.

  7. Non-equilibrium energy loss for very highly charged ions in insulators

    SciTech Connect

    Briere, M.A.; Schenkel, T.; Bauer, P.; Amau, A.

    1996-12-31

    The energy loss of 144 keV Ar{sup +16} ions on a bilayer structure of C-CaF{sub 2} has been measured. An asymmetry in the results is found depending on which layer is passed by the ion first: the energy loss is about four times larger when the CaF{sub 2} layer is traversed by the ion first. We interpret this as an indication of the existence of a nonequilibrium charge state of the Ar ions inside the solid in the case of the insulator.

  8. Investigation of the initial fragmentation of oligodeoxynucleotides in a quadrupole ion trap: charge level-related base loss.

    PubMed

    Pan, Su; Verhoeven, Kathryn; Lee, Jeehiun K

    2005-11-01

    The charge state distribution and CID fragmentation of two series of deprotonated oligodeoxynucleotide (ODN) 9-mers (5'-GGTTXTTGG-3' and 5'-CCAAYAACC-3', X/Y = G, C, A, or T) have been studied in detail in an ion trap in an effort to understand the intrinsic properties of DNA in vacuo. The distribution of charge states (-2 to -6) is similar for both the X- and Y-series, with the most abundant being the -4 charge state. The T-rich X-series prefers higher charge states (-6 and -5) than does the Y-series. Calculations show that phosphate groups located nearest a thymine are more acidic than those near an adenine, cytosine, or guanine, thus explaining why the X-series prefers higher charge states. We use the term "charge level" to define the ratio of the charge state to the total number of phosphate groups present in the ODN. We find, consistent with previous studies, that the initial step of fragmentation is loss of nucleobase either as an anion or as a neutral. We observe the former for ODNs with charge levels greater than 50% and the latter for ODNs with charge levels below 50%. The overall anionic base loss follows the trend A(-) > G(-) approximately T(-) > C(-); electrostatic potential calculations indicate that this trend follows delocalization of electron density for each anion, with A(-) being the most stabilized through delocalization. For neutral base loss, thymine (TH) is rarely cleaved, while the preferences for AH, GH, and CH loss vary. Proton affinity (PA) calculations show that a nearby negatively charged phosphate enhances the PA of proximally located nucleobases; this PA enhancement probably plays a role in promoting neutral base loss. The trends differ by charge level. At a charge level of 37.5% (-3 charge state), AH loss is preferred over CH and GH loss, regardless of sequence. However, at a charge level of 25% (-2 charge state), the terminal bases are preferentially lost over the internal bases, regardless of identity. By reconstructing the ODN

  9. A test protocol to screen capacitors for radiation-induced charge loss.

    SciTech Connect

    Zarick, Thomas Andrew; Hartman, E. Frederick

    2008-09-01

    This report presents a test protocol for screening capacitors dielectrics for charge loss due to ionizing radiation. The test protocol minimizes experimental error and provides a test method that allows comparisons of different dielectric types if exposed to the same environment and if the same experimental technique is used. The test acceptance or screening method is fully described in this report. A discussion of technical issues and possible errors and uncertainties is included in this report also.

  10. X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest

    SciTech Connect

    Otranto, S; Olson, R E; Beiersdorfer, P

    2005-09-19

    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 photon emission. A major shift in the line emission from being almost solely Lyman-{alpha} transitions at the highest collisions energies to strong high-n to 1s transitions at the lowest energies is observed. The calculated cross sections are in reasonable accord with measurements made by Greenwood et al, Phys. Rev. A 63, 062707 (2001), using O{sup 8+} and Ne{sup 10+} on various targets at 3 keV/amu. The calculations are also in accord with x-ray emission cross section data obtained on the EBIT machine at LLNL where O{sup 8+} and Ne{sup 10+} high resolution measurements were made at a temperature of 10 eV/amu for a series of targets with varying ionization potentials. The Ne{sup 10+} data clearly shows the contribution from multiple capture followed by Auger autoionization in the line emission spectra. Our calculated line emission cross sections are used to provide an ab initio determination of the soft x-ray spectrum of comet C/Linear 1999 S4 that was observed on the Chandra X-ray Observatory. The calculations show that the spectrum is due to charge exchange of the neutral gases in the comet's coma with the ions of the slow solar wind.

  11. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  12. Molecular target and projectile angular scattering effects in stopping power and charge exchange at low-to-intermediate projectile energies

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Öhrn, Y.; Sabin, John R.; Deumens, E.

    2002-02-01

    We analyze the implications of the molecular structure of a target and the angular scattering effects on projectile-target collisions within the Electron-Nuclear Dynamics (END) approach. We show the suitability of the END method for the analysis of molecular scattering processes such as differential cross sections, charge exchange, and energy loss as required for the study of the stopping cross section. As a consequence of these effects, we show that the rovibronic energy loss becomes of greatest importance at low projectile energies. Furthermore, we find that the Bragg additivity rule and the linear-velocity dependence of the stopping cross section are not fulfilled at low projectile energies. Finally, we analyze the differences in the scattering processes for molecular and atomic targets, and show that in a transmission experiment with small exit window, the acceptance angle corresponds to different impact parameter selection for molecular targets than for atomic ones. Thus, the measured stopping cross section becomes a function of the acceptance angle of the experimental setup. We present results for hydrogen beams on H2 and N2 gas targets.

  13. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak.

    PubMed

    Wei, Y L; Yu, D L; Liu, L; Ida, K; von Hellermann, M; Cao, J Y; Sun, A P; Ma, Q; Chen, W J; Liu, Yi; Yan, L W; Yang, Q W; Duan, X R; Liu, Yong

    2014-10-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle enable the temporal resolution of the system up to 400 Hz. The observation geometry and an optimized optic system enable the highest radial resolution up to ∼1 cm at the plasma edge. The CXRS system monitors the carbon line emission (C VI, n = 8-7, 529.06 nm) whose Doppler broadening and Doppler shift provide ion temperature and plasma rotation velocity during the neutral beam injection. The composite CX spectral data are analyzed by the atomic data and analysis structure charge exchange spectroscopy fitting (ADAS CXSFIT) code. First experimental results are shown for the case of HL-2A plasmas with sawtooth oscillations, electron cyclotron resonance heating, and edge transport barrier during the high-confinement mode (H-mode).

  14. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak

    NASA Astrophysics Data System (ADS)

    Wei, Y. L.; Yu, D. L.; Liu, L.; Ida, K.; von Hellermann, M.; Cao, J. Y.; Sun, A. P.; Ma, Q.; Chen, W. J.; Liu, Yi; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Liu, Yong

    2014-10-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle enable the temporal resolution of the system up to 400 Hz. The observation geometry and an optimized optic system enable the highest radial resolution up to ˜1 cm at the plasma edge. The CXRS system monitors the carbon line emission (C VI, n = 8-7, 529.06 nm) whose Doppler broadening and Doppler shift provide ion temperature and plasma rotation velocity during the neutral beam injection. The composite CX spectral data are analyzed by the atomic data and analysis structure charge exchange spectroscopy fitting (ADAS CXSFIT) code. First experimental results are shown for the case of HL-2A plasmas with sawtooth oscillations, electron cyclotron resonance heating, and edge transport barrier during the high-confinement mode (H-mode).

  15. First measurement of the edge charge exchange recombination spectroscopy on EAST tokamak

    NASA Astrophysics Data System (ADS)

    Li, Y. Y.; Yin, X. H.; Fu, J.; Jiang, D.; Feng, S. Y.; Lyu, B.; Shi, Y. J.; Yi, Y.; Zhou, X. J.; Hu, C. D.; Ye, M. Y.; Wan, B. N.

    2016-11-01

    An edge toroidal charge exchange recombination spectroscopy (eCXRS) diagnostic, based on a heating neutral beam injection (NBI), has been deployed recently on the Experimental Advanced Superconducting Tokamak (EAST). The eCXRS, which aims to measure the plasma ion temperature and toroidal rotation velocity in the edge region simultaneously, is a complement to the exiting core CXRS (cCXRS). Two rows with 32 fiber channels each cover a radial range from ˜2.15 m to ˜2.32 m with a high spatial resolution of ˜5-7 mm. Charge exchange emission of Carbon VI CVI at 529.059 nm induced by the NBI is routinely observed, but can be tuned to any interested wavelength in the spectral range from 400 to 700 nm. Double-slit fiber bundles increase the number of channels, the fibers viewing the same radial position are binned on the CCD detector to improve the signal-to-noise ratio, enabling shorter exposure time down to 5 ms. One channel is connected to a neon lamp, which provides the real-time wavelength calibration on a shot-to-shot basis. In this paper, an overview of the eCXRS diagnostic on EAST is presented and the first results from the 2015 experimental campaign will be shown. Good agreements in ion temperature and toroidal rotation are obtained between the eCXRS and cCXRS systems.

  16. Charge-exchange X-ray emission of nearby star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Liu, Jiren; Wang, Q. Daniel; Mao, Shude

    2012-03-01

    Properties of hot gas outflows from galaxies are generally measured from associated X-ray line emission assuming that it represents atomic transitions in thermally excited hot gas. X-ray line emission, however, can also arise from the charge exchange between highly ionized ions and neutral species. The Kα triplet of He-like ions can be used as a powerful diagnostic, because the charge-exchange X-ray emission (CXE) favours the intercombination and forbidden lines, while the thermal emission favours the resonance line. We analyse the O VII triplet of a sample of nine nearby star-forming galaxies observed by the XMM-Newton Reflection Grating Spectrometers. For most galaxies, the forbidden lines are comparable to or stronger than the resonance lines, which is in contrast to the thermal prediction. For NGC 253, M51, M83, M61, NGC 4631, and the Antennae (Arp 244), the observed line ratios are consistent with the ratio of CXE; for M94 and NGC 2903, the observed ratios indicate multiple origins; for M82, different regions show different line ratios, also indicating multiple origins. We discuss other possible mechanisms that can produce a relatively strong forbidden line, such as a collisional non-equilibrium-ionization recombining/ionizing plasma, which are not favoured. These results suggest that the CXE may be a common phenomenon and contribute a significant fraction of the soft X-ray line emission for galaxies with massive star formation.

  17. Laser-Controlled Antihydrogen Production by Two-Stage Charge Exchange

    SciTech Connect

    Storry, C.H.; Comeau, D.; George, M.; Hessels, E.A.; Guise, N.; Levitt, B.; Le Sage, D.; Speck, A.; Gabrielse, G.; Grzonka, D.; Oelert, W.; Schepers, G.; Sefzick, T.; Pittner, H.; Herrmann, M.; Walz, J.; Haensch, T.W.

    2005-10-26

    Our ATRAP collaboration has now demonstrated a second technique for antihydrogen (H-bar) production. Lasers are used for the first time to control the production of H-baratoms in our cryogenic apparatus at CERN. As suggested in ref. [2] and first reported in ref. [1], lasers excite a thermal beam of cesium (Cs) atoms to a Rydberg state. In a first charge exchange collision one of these laser-excited Cs atoms (Cs*) and a cold e+ produces positronium (Ps). Our measurements at Harvard([3]) and at CERN([1]) confirm CTMC simulations([2]) that the laser-selected binding energy in the Cs atom is preserved by the collision and results in Ps with the selected binding energy. A second charge exchange is between one of these Ps atoms and a trapped p-bar. H-baris produced by this second collision and is expected to again have the same binding energy. One advantage of this technique as discussed in ref. [2] is that the H-barproduced is expected to be extremely cold, at the temperature of the trapped p-bar, allowing for possible confinement of the H-baratoms in a magnetic trap.

  18. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak

    SciTech Connect

    Wei, Y. L.; Yu, D. L. Liu, L.; Cao, J. Y.; Sun, A. P.; Ma, Q.; Chen, W. J.; Liu, Yi; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Liu, Yong; Ida, K.; Hellermann, M. von

    2014-10-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle enable the temporal resolution of the system up to 400 Hz. The observation geometry and an optimized optic system enable the highest radial resolution up to ~1 cm at the plasma edge. The CXRS system monitors the carbon line emission (C VI, n = 8–7, 529.06 nm) whose Doppler broadening and Doppler shift provide ion temperature and plasma rotation velocity during the neutral beam injection. The composite CX spectral data are analyzed by the atomic data and analysis structure charge exchange spectroscopy fitting (ADAS CXSFIT) code. First experimental results are shown for the case of HL-2A plasmas with sawtooth oscillations, electron cyclotron resonance heating, and edge transport barrier during the high-confinement mode (H-mode)

  19. Ionosphere-exosphere coupling through charge exchange and momentum transfer in hydrogen-proton collisions

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.; Breig, E. L.

    1991-01-01

    The implications of a traditional assumption of exospheric physics, that collisions of hydrogen atoms and protons preferentially result in charge exchange with negligible momentum transfer are examined. Initially adopted as a necessary convenience to accommodate limited computer resources in exosphere model calculations, this approximation results in a direct transformation of the proton velocity distribution into a hot component of neutral hydrogen. With expanding computational facilities, the need for the approximation has passed. As the first step toward its replacement with a realistic, quantum mechanical model of the H - H(+) collision process, differential and cumulative cross sections were calculated for quantum elastic scattering of indistinguishable nuclei for a fine grid of encounter energies and scattering angles. These data are used to study the nature of ionosphere-exosphere coupling through H - H(+) collisions, and to demonstrate that the distribution of velocities of scattered H produced in the traditional exospheric charge exchange approximation, as well as that arising from an alternative, fluid dynamic approach, leads to unacceptable abundances of coronal atoms in long-term, highly elliptic trajectories.

  20. A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITERa)

    NASA Astrophysics Data System (ADS)

    Jaspers, R. J. E.; Scheffer, M.; Kappatou, A.; van der Valk, N. C. J.; Durkut, M.; Snijders, B.; Marchuk, O.; Biel, W.; Pokol, G. I.; Erdei, G.; Zoletnik, S.; Dunai, D.

    2012-10-01

    A feasibility study for the use of core charge exchange recombination spectroscopy on ITER has shown that accurate measurements on the helium ash require a spectrometer with a high etendue of 1mm2sr to comply with the measurement requirements [S. Tugarinov et al., Rev. Sci. Instrum. 74, 2075 (2003)], 10.1063/1.1537443. To this purpose such an instrument has been developed consisting of three separate wavelength channels (to measure simultaneously He/Be, C/Ne, and H/D/T together with the Doppler shifted direct emission of the diagnostic neutral beam, the beam emission (BES) signal), combining high dispersion (0.02 nm/pixel), sufficient resolution (0.2 nm), high efficiency (55%), and extended wavelength range (14 nm) at high etendue. The combined measurement of the BES along the same sightline within a third wavelength range provides the possibility for in situ calibration of the charge eXchange recombination spectroscopy signals. In addition, the option is included to use the same instrument for measurements of the fast fluctuations of the beam emission intensity up to 2 MHz, with the aim to study MHD activity.

  1. DXL: A sounding rocket mission measuring Solar Wind Charge eXchange properties

    NASA Astrophysics Data System (ADS)

    Galeazzi, Massimiliano

    2016-04-01

    Solar Wind interacts with the interstellar neutrals via charge exchange mechanism to produce spatially and temporally varying x-rays making it difficult to separate from other diffuse sources. The Diffuse X-rays from the Local Galaxy (DXL) mission measured the spatial signature of Solar Wind Charge eXchange (SWCX) emission due to the helium focusing cone. The mission used 2 large area proportional counters and was able to separate the SWCX contribution from Local Hot Bubble emission. The data from the mission provide a robust estimate of the SWCX contribution to the ROSAT maps, measuring the compound SWCX cross section with He in all ROSAT bands. The results showed that the total SWCX contribution in the ¼ keV band is, on average, ~27%. A new mission, DXL-2, was launched on December 4, 2015 with two new counters for a better understanding of the energy distribution of heliospheric SWCX photons, by using a multi-band approach. A dedicated scan to accurately measure the cone position and solve the IBEX controversy was also performed. The talk will discuss the DXL mission, the results from the first flight, and the preliminary results from the latest flight.Submitted for the DXL Collaboration

  2. Determination of plasma ion velocity distribution via charge-exchange recombination spectroscopy

    SciTech Connect

    Fonck, R.J.; Darrow, D.S.; Jaehnig, K.P.

    1983-12-01

    Spectroscopy of line radiation from plasma impurity ions excited by charge-exchange recombination reactions with energetic neutral beam atoms is rapidly becoming recognized as a powerful technique for measuring ion temperature, bulk plasma motion, impurity transport, and more exotic phenomena such as fast alpha particle distributions. In particular, this diagnostic offers the capability of obtaining space- and time-resolved ion temperature and toroidal plasma rotation profiles with relatively simple optical systems. Cascade-corrected excitation rate coefficients for use in both fully stripped impurity density studies and ion temperature measurements have been calculated to the principal ..delta..n = 1 transitions of He+, C/sup 5 +/, and O/sup 7 +/ with neutral beam energies of 5 to 100 keV/amu. A fiber optically coupled spectrometer system has been used on PDX to measure visible He/sup +/ radiation excited by charge exchange. Central ion temperatures up to 2.4 keV and toroidal rotation speeds up to 1.5 x 10/sup 7/ cm/s were observed in diverted discharges with P/sub INJ/ less than or equal to 3.0 MW.

  3. Determination of plasma-ion velocity distribution via charge-exchange recombination spectroscopy

    NASA Astrophysics Data System (ADS)

    Fonck, R. J.; Darrow, D. S.; Jaehnig, K. P.

    1984-06-01

    Spectroscopy of line radiation from plasma impurity ions excited by charge-exchange recombination reactions with energetic neutral-beam atoms is rapidly becoming recognized as a powerful diagnostic for magnetically confined tokamak plasmas. Ion temperature, bulk plasma motion, impurity transport, and more exotic phenomena such as fast alpha-particle distributions can all be measured with this technique. In particular, it offers the capability of obtaining space- and time-resolved ion temperature and toroidal plasma rotation profiles with relatively simple optical systems. Cascade-corrected excitation rate coefficients for use in both fully stripped impurity density studies and ion-temperature measurements have been calculated for the principal Δn=1 transitions of He+, C5+, and O7+ with neutral-beam energies of 5-100 keV/amu. Line intensities and profiles can be affected by atomic fine structure, l-mixing collisions, motional Stark effects, and product ions created in the neutral-beam region which drift into the viewing sightline. General estimates of the importance of these effects for the transitions of interest are provided, along with specific examples calculated for the PDX (Poloidal Divertor Experiment) and TFTR (Tokamak Fusion Test Reactor) tokamaks. A fiber optically coupled spectrometer system has been used on PDX to measure visible He+ radiation excited by charge exchange to illustrate some of these points. Central ion temperatures up to 2.4 keV and toroidal rotation speeds up to 1.5×107 cm/s were observed.

  4. CHARGE-EXCHANGE LIMITS ON LOW-ENERGY {alpha}-PARTICLE FLUXES IN SOLAR FLARES

    SciTech Connect

    Hudson, H. S.; Fletcher, L.; MacKinnon, A. L.; Woods, T. N.

    2012-06-20

    This paper reports on a search for flare emission via charge-exchange radiation in the wings of the Ly{alpha} line of He II at 304 A, as originally suggested for hydrogen by Orrall and Zirker. Via this mechanism a primary {alpha} particle that penetrates into the neutral chromosphere can pick up an atomic electron and emit in the He II bound-bound spectrum before it stops. The Extreme-ultraviolet Variability Experiment on board the Solar Dynamics Observatory gives us our first chance to search for this effect systematically. The Orrall-Zirker mechanism has great importance for flare physics because of the essential roles that particle acceleration plays; this mechanism is one of the few proposed that would allow remote sensing of primary accelerated particles below a few MeV nucleon{sup -1}. We study 10 events in total, including the {gamma}-ray events SOL2010-06-12 (M2.0) and SOL2011-02-24 (M3.5) (the latter a limb flare), seven X-class flares, and one prominent M-class event that produced solar energetic particles. The absence of charge-exchange line wings may point to a need for more complete theoretical work. Some of the events do have broadband signatures, which could correspond to continua from other origins, but these do not have the spectral signatures expected from the Orrall-Zirker mechanism.

  5. A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITER.

    PubMed

    Jaspers, R J E; Scheffer, M; Kappatou, A; van der Valk, N C J; Durkut, M; Snijders, B; Marchuk, O; Biel, W; Pokol, G I; Erdei, G; Zoletnik, S; Dunai, D

    2012-10-01

    A feasibility study for the use of core charge exchange recombination spectroscopy on ITER has shown that accurate measurements on the helium ash require a spectrometer with a high etendue of 1mm(2)sr to comply with the measurement requirements [S. Tugarinov et al., Rev. Sci. Instrum. 74, 2075 (2003)]. To this purpose such an instrument has been developed consisting of three separate wavelength channels (to measure simultaneously He/Be, C/Ne, and H/D/T together with the Doppler shifted direct emission of the diagnostic neutral beam, the beam emission (BES) signal), combining high dispersion (0.02 nm/pixel), sufficient resolution (0.2 nm), high efficiency (55%), and extended wavelength range (14 nm) at high etendue. The combined measurement of the BES along the same sightline within a third wavelength range provides the possibility for in situ calibration of the charge eXchange recombination spectroscopy signals. In addition, the option is included to use the same instrument for measurements of the fast fluctuations of the beam emission intensity up to 2 MHz, with the aim to study MHD activity.

  6. Upgrade of the Edge Charge Exchange Diagnostic on Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    McDermott, Rachael; Lipschultz, Bruce; Marr, Kenneth

    2006-10-01

    The current edge Charge Exchange Spectroscopy system is being upgraded to include both a beam viewing and a background viewing toroidal periscope. The beam viewing periscope will be focused on the center of the DNB and will cover a 4cm radial region at the edge of the plasma starting a few centimeters in from and extending up to 1centimeter outside of the last closed flux surface. The background periscope will view the same radial region but will be displaced toroidally by 36 degrees. Each periscope has 20 chordal views with a radial resolution of 2.5-3mm. The presence of a background periscope obviates the need for a chopped DNB by providing time synchronized background B^+4 spectral data that can be subtracted directly from the active beam-derived B^+4 line-shapes. This system has been designed to work in conjunction with the current poloidal Charge Exchange periscope which has 25 fibers focused in the same region with equivalent radial resolution. The new toroidal system will enable concurrent measurements of the poloidal and toroidal velocity as well as the temperature and density of the B^+5 ions in the edge pedestal region; a measurement that currently does not exist on C-Mod. This information will then be used to calculate radial electric field profiles and study edge physics phenomena.

  7. Colliding planetary and stellar winds: charge exchange and transit spectroscopy in neutral hydrogen

    NASA Astrophysics Data System (ADS)

    Tremblin, Pascal; Chiang, Eugene

    2013-01-01

    When transiting their host stars, hot Jupiters absorb about 10 per cent of the light in the wings of the stellar Lyman α emission line. The absorption occurs at wavelengths Doppler-shifted from line centre by ±100 km s-1 - larger than the thermal speeds with which partially neutral, ˜104 K hydrogen escapes from hot Jupiter atmospheres. It has been proposed that the absorption arises from ˜106 K hydrogen from the host stellar wind, made momentarily neutral by charge exchange with planetary H i. The ±100 km s-1 velocities would then be attributed to the typical velocity dispersions of protons in the stellar wind - as inferred from spacecraft measurements of the solar wind. To test this proposal, we perform 2D hydrodynamic simulations of colliding hot Jupiter and stellar winds, augmented by a chemistry module to compute the amount of hot neutral hydrogen produced by charge exchange. We observe the contact discontinuity where the two winds meet to be Kelvin-Helmholtz unstable. The Kelvin-Helmholtz instability mixes the two winds; in the mixing layer, charge exchange reactions establish, within tens of seconds, a chemical equilibrium in which the neutral fraction of hot stellar hydrogen equals the neutral fraction of cold planetary hydrogen (about 20 per cent). In our simulations, enough hot neutral hydrogen is generated to reproduce the transit observations, and the amount of absorption converges with both spatial resolution and time. Our calculations support the idea that charge transfer between colliding winds correctly explains the Lyman α transit observations - modulo the effects of magnetic fields, which we do not model but which may suppress mixing. Other neglected effects include, in order of decreasing importance, rotational forces related to orbital motion, gravity and stellar radiation pressure; we discuss quantitatively the errors introduced by our approximations. How hot stellar hydrogen cools when it collides with cold planetary hydrogen is also

  8. Recent Advances in Computational Studies of Charge Exchange X-ray Emission

    NASA Astrophysics Data System (ADS)

    Cumbee, Renata

    2016-06-01

    Interest in astrophysical sources of charge exchange (CX) has grown since X-ray emission from comet Hyakutake was first observed, the origin of which is primarily due to CX processes between neutral species in the comet’s atmosphere and highly charged ions from the solar wind. More recent observations have shown that CX may have a significant contribution to the X-ray emission spectra of a wide variety of environments within our solar system including solar wind charge exchange (SWCX) with neutral gases in the heliosphere and in planetary atmospheres, as well as beyond the solar system in galaxy clusters, supernova remnants, and star forming galaxies.While the basic process of CX has been studied for many decades, the reliability of the existing data is not uniform, and the coverage of the astrophysically important projectile and target combinations and collisional velocities is insufficient. The need for reliable and robust CX X-ray emission models will only be amplified with the with the high resolution X-ray spectra expected from the soft X-ray imaging calorimeter spectrometer (SXS) onboard the Hitomi X-ray observatory. In this talk, I will discuss recent advances in theoretical CX cross sections and X-ray modeling with a focus on CX diagnostics. The need for experimental X-ray spectra and cross sections for benchmarking current theory will also be highlighted. This work was performed in collaboration with David Lyons, Patrick Mullen, David Schultz, Phillip Stancil, and Robin Shelton. Work at UGA was partially supported by NASA grant NNX09AC46G.

  9. Production of high brightness H- beam by charge exchange of hydrogen atom beam in sodium jet

    SciTech Connect

    Davydenko, V.; Zelenski, A.; Ivanov, A.; Kolmogorov, A.

    2010-11-16

    Production of H{sup -} beam for accelerators applications by charge exchange of high brightness hydrogen neutral beam in a sodium jet cell is experimentally studied in joint BNL-BINP experiment. In the experiment, a hydrogen-neutral beam with 3-6 keV energy, equivalent current up to 5 A and 200 microsecond pulse duration is used. The atomic beam is produced by charge exchange of a proton beam in a pulsed hydrogen target. Formation of the proton beam is performed in an ion source by four-electrode multiaperture ion-optical system. To achieve small beam emittance, the apertures in the ion-optical system have small enough size, and the extraction of ions is carried out from the surface of plasma emitter with a low transverse ion temperature of {approx}0.2 eV formed as a result of plasma jet expansion from the arc plasma generator. Developed for the BNL optically pumped polarized ion source, the sodium jet target with recirculation and aperture diameter of 2 cm is used in the experiment. At the first stage of the experiment H{sup -} beam with 36 mA current, 5 keV energy and {approx}0.15 cm {center_dot} mrad normalized emittance was obtained. To increase H{sup -} beam current ballistically focused hydrogen neutral beam will be applied. The effects of H{sup -} beam space-charge and sodium-jet stability will be studied to determine the basic limitations of this approach.

  10. The velocity dependence of X-ray emission due to Charge Exchange in the Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Cumbee, Renata; Lyons, David; Mullen, Patrick Dean; Shelton, Robin L.; Stancil, Phillip C.; Schultz, David R.

    2016-01-01

    The fundamental collisional process of charge exchange (CX) has been been established as a primary source of X-ray emission from the heliosphere [1], planetary exospheres [2], and supernova remnants [3,4]. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly-excited, high charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays.To provide reliable CX-induced X-ray spectral models to realistically simulate these environments, line ratios and spectra are computed using theoretical CX cross-sections obtained with the multi-channel Landau-Zener, atomic-orbital close-coupling, and classical-trajectory Monte Carlo methods for various collisional velocities relevant to astrophysics for collisions of bare and H-like C to Al ions with H, He, and H2. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant will be shown as an example with ion velocity dependence.[1] Henley, D. B. & Shelton, R. L. 2010, ApJSS, 187, 388[2] Dennerl, K. et al. 2002, A&A 386, 319[3] Katsuda, S. et al. 2011, ApJ 730 24[4] Cumbee, R. S. et al. 2014, ApJ 787 L31This work was partially supported by NASA grant NNX09AC46G.

  11. Charge exchange in cometary coma: Discovery of H− ions in the solar wind close to comet 67P/Churyumov‐Gerasimenko

    PubMed Central

    Cravens, T. E.; Llera, K.; Goldstein, R.; Mokashi, P.; Tzou, C.‐Y.; Broiles, T.

    2015-01-01

    Abstract As Rosetta was orbiting comet 67P/Churyumov‐Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well‐known cross sections and energy‐loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H− ions in the solar wind by double charge exchange with molecules in the coma.

  12. Charge exchange in cometary coma: Discovery of H− ions in the solar wind close to comet 67P/Churyumov‐Gerasimenko

    PubMed Central

    Cravens, T. E.; Llera, K.; Goldstein, R.; Mokashi, P.; Tzou, C.‐Y.; Broiles, T.

    2015-01-01

    Abstract As Rosetta was orbiting comet 67P/Churyumov‐Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well‐known cross sections and energy‐loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H− ions in the solar wind by double charge exchange with molecules in the coma. PMID:27656008

  13. The role of spin exchange in charge transfer in low-bandgap polymer: Fullerene bulk heterojunctions

    SciTech Connect

    Krinichnyi, V. I. Yudanova, E. I.; Denisov, N. N.

    2014-07-28

    Formation, relaxation and dynamics of polarons and methanofullerene anion radicals photoinitiated in poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′, 3′-benzothiadiazole)]:-[6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PCDTBT:PC{sub 61}BM) bulk heterojunctions were studied mainly by light-induced EPR (LEPR) spectroscopy in wide photon energy and temperature ranges. Some polarons are pinned by spin traps whose number and depth are governed by the composite morphology and photon energy. The proximity of the photon energy and the polymer bandgap reduces the number of such traps, inhibits recombination of mobile charge carriers, and facilitates their mobility in polymer network. Spin relaxation and charge carrier dynamics were studied by the steady-state saturation method at wide range of temperature and photon energy. These processes were shown to be governed by spin exchange as well as by the photon energy. Charge transfer in the composite is governed by the polaron scattering on the lattice phonons of crystalline domains embedded into amorphous polymer matrix and its activation hopping between polymer layers. The energy barrier required for polaron interchain hopping exceeds that of its intrachain diffusion. Anisotropy of polaron dynamics in the PCDTBT:PC61BM composite is less than that of poly(3-alkylthiophenes)-based systems that evidences for better ordering of the former. Lorentzian shape of LEPR lines of both charge carriers, lower concentration of spin traps as well as behaviours of the main magnetic resonance parameters were explained by layer ordered morphology of polymer matrix.

  14. The role of spin exchange in charge transfer in low-bandgap polymer: Fullerene bulk heterojunctions.

    PubMed

    Krinichnyi, V I; Yudanova, E I; Denisov, N N

    2014-07-28

    Formation, relaxation and dynamics of polarons and methanofullerene anion radicals photoinitiated in poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]:-[6,6]-phenyl-C61-butyric acid methyl ester (PCDTBT:PC61BM) bulk heterojunctions were studied mainly by light-induced EPR (LEPR) spectroscopy in wide photon energy and temperature ranges. Some polarons are pinned by spin traps whose number and depth are governed by the composite morphology and photon energy. The proximity of the photon energy and the polymer bandgap reduces the number of such traps, inhibits recombination of mobile charge carriers, and facilitates their mobility in polymer network. Spin relaxation and charge carrier dynamics were studied by the steady-state saturation method at wide range of temperature and photon energy. These processes were shown to be governed by spin exchange as well as by the photon energy. Charge transfer in the composite is governed by the polaron scattering on the lattice phonons of crystalline domains embedded into amorphous polymer matrix and its activation hopping between polymer layers. The energy barrier required for polaron interchain hopping exceeds that of its intrachain diffusion. Anisotropy of polaron dynamics in the PCDTBT:PC61BM composite is less than that of poly(3-alkylthiophenes)-based systems that evidences for better ordering of the former. Lorentzian shape of LEPR lines of both charge carriers, lower concentration of spin traps as well as behaviours of the main magnetic resonance parameters were explained by layer ordered morphology of polymer matrix. PMID:25084955

  15. High resolution main-ion charge exchange spectroscopy in the DIII-D H-mode pedestal

    NASA Astrophysics Data System (ADS)

    Grierson, B. A.; Burrell, K. H.; Chrystal, C.; Groebner, R. J.; Haskey, S. R.; Kaplan, D. H.

    2016-11-01

    A new high spatial resolution main-ion (deuterium) charge-exchange spectroscopy system covering the tokamak boundary region has been installed on the DIII-D tokamak. Sixteen new edge main-ion charge-exchange recombination sightlines have been combined with nineteen impurity sightlines in a tangentially viewing geometry on the DIII-D midplane with an interleaving design that achieves 8 mm inter-channel radial resolution for detailed profiles of main-ion temperature, velocity, charge-exchange emission, and neutral beam emission. At the plasma boundary, we find a strong enhancement of the main-ion toroidal velocity that exceeds the impurity velocity by a factor of two. The unique combination of experimentally measured main-ion and impurity profiles provides a powerful quasi-neutrality constraint for reconstruction of tokamak H-mode pedestals.

  16. A comet's tale: Role of charge exchange in the plasma environment of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Wedlund, Cyril Simon; Kallio, Esa; Alho, Markku; Dyadechkin, Sergey; Nilsson, Hans; Stenberg Wieser, Gabriella; Béhar, Etienne; Gunell, Herbert; Holmström, Mats

    2015-04-01

    On 6 Aug. 2014, the Rosetta mission arrived in the vicinity of comet 67P/Churyumov-Gerasimenko (C-G) and started measuring its complex plasma environment, using notably the RPC-ICA ion spectrometer (Rosetta Plasma Consortium Ion Composition Analyser). A simple model of charge-exchange processes is first presented for He2+ and H+ solar wind ions that efficiently convert them into He+ ions (measured by RPC-ICA) and H energetic neutral atoms, respectively. In a second step, we present a new cometary hybrid plasma model, taking into account photoionisation, charge-exchange, electron impact ionisation and electron recombination, dedicated to the interpretation of RPC-ICA measurements. We use this global model to investigate in more detail the role of the water production rate and charge-exchange processes in the formation of plasma regions at comet 67P/C-G and for various heliocentric distances.

  17. What can be Learned from X-Ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes

    NASA Technical Reports Server (NTRS)

    Snowden, Steven L.

    2007-01-01

    Solar wind charge exchange produces diffuse X-ray emission with a variable surface brightness comparable to that of the cosmic background. While the temporal variation of the charge exchange emission allows some separation of the components, there remains a great deal of uncertainty as to the zero level of both. Because the production mechanisms of the two components are considerably different, their spectra would provide critical diagnostics to the understanding of both. However, current X-ray observatories are very limited in both spectral resolution and sensitivity in the critical soft X-ray (less than 1.0 keV) energy range. Non-dispersive high-resolution spectrometers, such as the calorimeter proposed for the Spectrum Roentgen Gamma mission, will be extremely useful in distinguishing the cascade emission of charge exchange from the spectra of thermal bremsstrahlung cosmic plasmas.

  18. Models of Heliospheric solar wind charge exchange X-ray emission

    NASA Astrophysics Data System (ADS)

    Koutroumpa, Dimitra

    2016-04-01

    The first models of the solar wind charge exchange (SWCX) X-ray production in the heliosphere were developed shortly after the discovery of SWCX emission at the end of 1990s. Since then, continuous monitoring of the global solar wind evolution through the solar cycle has allowed better constraints on its interaction with the interstellar neutrals. We have a fairly accurate description of the interstellar neutral density distributions in interplanetary space. However, the solar wind heavy ion fluxes, and especially their short term variability and propagation through interplanetary space, have remained relatively elusive due to the sparseness or lack of in situ data, especially towards high ecliptic latitudes. In this talk, I will present a summary the heliospheric SWCX modeling efforts, and an overview of the global solar cycle variability of heliospheric SWCX emission, while commenting on the difficulties of modeling the real-time variability of the heliospheric X-ray signal.

  19. New Missions and the Future of Solar Wind Charge Exchange Studies

    NASA Astrophysics Data System (ADS)

    Kuntz, K. D.

    2016-04-01

    Several newly approved missions in astrophysics and heliophysics will study solar wind charge-exchange (SWCX) directly as either primary or secondary science goals. Of these, SMILE and CuPID will study the magnetosheath by means of the SWCX emission and will provide a direct measure of the magnetospheric emission from in both the 1/4 keV and 3/4 keV bands. HaloSAT observations will be designed to minimize the magnetospheric component for its observations of the Galactic Halo, but will make at least some dedicated observations of heliospheric SWCX. I will outline the simulation needs and observational strategies required to study SWCX for astrophysical purposes.

  20. Ion temperature by charge exchange neutral analysis from vertical sightlines on the Tokamak Fusion Test Reactor

    SciTech Connect

    Fiore, C.L.; Medley, S.S.; Hammett, G.W.; Kaita, R.; Scott, S.D.

    1987-12-01

    The Fokker-Planck code FPPRF is used to calculate the expected deuterium charge exchange flux along vertical sighlines from TFTR neutral-beam-injected discharges. The feasibility of obtaining central ion temperature measurements by fitting the spectra obtained from these sightlines at two energy regions--above the highest neutral beam injection energy (> 100 keV) and from 20-80 keV--is investigated. It is demonstrated that the central ion temperature can be obtained from the central vertical slightline for fitting the high energy data. The deuterium neutral particle flux energy distribution below the neutral beam injection energy is insentive to the code input ion temperature, however. 6 refs., 12 figs., 1 tab.

  1. Design of charge exchange recombination spectroscopy for the joint Texas experimental tokamak

    SciTech Connect

    Chi, Y.; Zhuang, G. Cheng, Z. F.; Hou, S. Y.; Cheng, C.; Li, Z.; Wang, J. R.; Wang, Z. J.

    2014-11-15

    The old diagnostic neutral beam injector first operated at the University of Texas at Austin is ready for rejoining the joint Texas experimental tokamak (J-TEXT). A new set of high voltage power supplies has been equipped and there is no limitation for beam modulation or beam pulse duration henceforth. Based on the spectra of fully striped impurity ions induced by the diagnostic beam the design work for toroidal charge exchange recombination spectroscopy (CXRS) system is presented. The 529 nm carbon VI (n = 8 − 7 transition) line seems to be the best choice for ion temperature and plasma rotation measurements and the considered hardware is listed. The design work of the toroidal CXRS system is guided by essential simulation of expected spectral results under the J-TEXT tokamak operation conditions.

  2. Charge-exchange reactions from the standpoint of the parton model

    NASA Astrophysics Data System (ADS)

    Nekrasov, M. L.

    2015-11-01

    Using simple arguments, we show that charge-exchange reactions at high energies go through the hard scattering of fast quarks. On this basis we describe π-p→ M0n and K-p→ M0Λ, M0=π0,η,η', in a combined approach which defines hard contributions in the parton model and soft ones in Regge phenomenology. The disappearance of a dip according to recent GAMS- 4π data in the differential cross-section K-p→ηΛ at \\vert t\\vert≈ 0.4-0.5 (GeV/c)2 at transition to relatively high momenta, is explained as a manifestation of a mode change of summation of hard contributions from coherent to incoherent. Other manifestations of the mentioned mode change are discussed. Constraints on the η- η{^' mixing and gluonium admixture in η{^' are obtained.

  3. Inference of the ring current ion composition by means of charge exchange decay

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Bewtra, N. K.

    1981-01-01

    The analysis of data from the Explorer 45 (S3-A) electrostatic analyzer in the energy range 5-30 keV has provided some new results on the ring current ion composition. It has been well established that the storm time ring current has a decay time of several days, during which the particle fluxes decrease nearly monotonically. By analyzing the measured ion fluxes during the several day storm recovery period and assuming that beside hydrogen other ions were present and that the decays were exponential in nature, three separate lifetimes for the ions were established. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+) and He(+) in the energy and L value range of the data.

  4. Delta excitations and shell-model information in heavy-ion, charge-exchange reactions

    NASA Technical Reports Server (NTRS)

    Deutchman, P. A.; Maung, K. M.; Norbury, J. W.; Rasmussen, J. O.; Townsend, L. W.

    1986-01-01

    We calculate total cross sections for coherent pion production using localized plane-wave approximations for the shell-structure of valence nucleons that are excited to delta particles in the intermediate state in the (12C, 12B) and (12C, 12N) charge-exchange, heavy-ion reactions. We find comparable agreement to projectile downshift data for 12C(12C, 12B)12N. Then we improve the formalism by replacing the localized plane wave bound states with harmonic oscillator states which are imbedded in a multipole expansion approach and calculate pion differential cross sections to test for the sensitivity of the spectra to the single-particle mass parameter.

  5. Propagation of charge-exchange plasma produced by an ion thruster

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.; Brady, M. E.

    1981-01-01

    Under the proper conditions there is an end-effect of a long, cylindrical Langmuir probe which allows a significant increase in collected ion current when the probe is aligned with a flowing plasma. This effect was used to determine the charge-exchange plasma flow direction at various locations relative to the ion thruster. The ion current collected by the probe as a function of its angle with respect to the plasma flow allows determination of the plasma density and plasma flow velocity at the probe's location upstream of the ion thruster optics. The density values obtained from the ion current agreed to within a factor of two of density values obtained by typical voltage-current Langmuir probe characteristics.

  6. Spin dipole nuclear matrix elements for double beta decay nuclei by charge-exchange reactions

    NASA Astrophysics Data System (ADS)

    Ejiri, H.; Frekers, D.

    2016-11-01

    Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (3He, t) charge-exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) {M}α ({{SD}}) for low-lying 2‑ states were derived from the experimental SD strengths by referring to the experimental α = GT (Gamow–Teller) and α = F (Fermi) strengths. They are consistent with the empirical NMEs M({{SD}}) based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.

  7. Can Charge Exchange Explain Anomalous Soft X-Ray Emission in the Cygnus Loop?

    NASA Astrophysics Data System (ADS)

    Cumbee, R. S.; Henley, D. B.; Stancil, P. C.; Shelton, R. L.; Nolte, J. L.; Wu, Y.; Schultz, D. R.

    2014-06-01

    Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this "anomalously" enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of O8 +, O7 +, N7 +, N6 +, C6 +, and C5 + with H with an energy of 1 keV u-1 (438 km s-1). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically O7 + + H, does provide for a statistically significant improvement over a pure shock model.

  8. Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei

    SciTech Connect

    Martini, M.; Goriely, S.; Péru, S.

    2014-06-15

    In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.

  9. Charge-exchange recombination spectroscopy of the plasma ion temperature at the T-10 tokamak

    SciTech Connect

    Krupin, V. A.; Tugarinov, S. N.; Barsukov, A. G.; Dnestrovskij, A. Yu.; Klyuchnikov, L. A.; Korobov, K. V.; Krasnyanskii, S. A.; Naumenko, N. N.; Nemets, A. R.; Sushkov, A. V.; Tilinin, G. N.

    2013-08-15

    Charge-exchange recombination spectroscopy (CXRS) based on a diagnostic neutral beam has been developed at the T-10 tokamak. The diagnostics allows one to measure the ion temperature profile in the cross section of the plasma column. In T-10 experiments, the measurement technique was adjusted and the elements of the CXRS diagnostics for ITER were tested. The used spectroscopic equipment makes it possible to reliably determine the ion temperature from the Doppler broadening of impurity lines (helium, carbon), as well as of the spectral lines of the working gas. The profiles of the plasma ion temperature in deuterium and helium discharges were measured at different plasma currents and densities, including with the use of active Doppler measurements of lines of different elements. The validity and reliability of ion temperature measurements performed by means of the developed CXRS diagnostics are analyzed.

  10. 'Coulomb' description of basic relaxation parameters of isobar analog and charge-exchange giant monopole resonances

    SciTech Connect

    Gorelik, M. L.; Rykovanov, V. S.; Urin, M. G.

    2010-12-15

    Within a semimicroscopic approach, basic relaxation parameters of the isobaric analog resonance and of the charge-exchange giant monopole resonance, which is an overtone of the isobaric analog resonance, are interpreted in terms of the mean Coulomb field of a nucleus. The continuum version of the random-phase approximation, allowance for an approximate isospin conservation in nuclei in an explicit form, and a phenomenological description of the fragmentation effect are basic ingredients of the approach used. The aforementioned parameters were calculated for a number of magic and near-magic nuclei by using a partly self-consistent phenomenological nuclear mean field and the isovector part of the Landau-Migdal interaction in the particle-hole channel. The results of the calculations are compared with corresponding experimental data.

  11. Observation of Solar Wind Charge Exchange Emission from Exospheric Material in and Outside Earth's Magnetosheath

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Collier, M. R.; Cravens, T.; Kuntz, K. D.; Lepri, S. T.; Robertson, I.; Tomas, L.

    2008-01-01

    A long XMM-Newton exposure is used to observe solar wind charge exchange (SWCX) emission from exospheric material in and outside Earth s magnetosheath. The light curve of the O VII (0.5-0.62 keV) band is compared with a model for the expected emission, and while the emission is faint and the light curve has considerable scatter, the correlation is significant to better than 99.9%. This result demonstrates the validity of the geocoronal SWCX emission model for predicting a contribution to astrophysical observations to a scale factor of order unity (1.36). The results also demonstrate the potential utility of using X-ray observations to study global phenomena of the magnetosheath which currently are only investigated using in situ measurements.

  12. Development of the charge exchange recombination spectroscopy and the beam emission spectroscopy on the EAST tokamak.

    PubMed

    Li, Y Y; Fu, J; Lyu, B; Du, X W; Li, C Y; Zhang, Y; Yin, X H; Yu, Y; Wang, Q P; von Hellermann, M; Shi, Y J; Ye, M Y; Wan, B N

    2014-11-01

    Charge eXchange Recombination Spectroscopy (CXRS) and Beam Emission Spectroscopy (BES) diagnostics based on a heating neutral beam have recently been installed on EAST to provide local measurements of ion temperature, velocity, and density. The system design features common light collection optics for CXRS and BES, background channels for the toroidal views, multi-chord viewing sightlines, and high throughput lens-based spectrometers with good signal to noise ratio for high time resolution measurements. Additionally, two spectrometers each has a tunable grating to observe any wavelength of interest are used for the CXRS and one utilizes a fixed-wavelength grating to achieve higher diffraction efficiency for the BES system. A real-time wavelength correction is implemented to achieve a high-accuracy wavelength calibration. Alignment and calibration are performed. Initial performance test results are presented.

  13. Impact of calibration technique on measurement accuracy for the JET core charge-exchange system.

    PubMed

    Giroud, Carine; Meigs, A G; Negus, C R; Zastrow, K-D; Biewer, T M; Versloot, T W

    2008-10-01

    The core charge-exchange diagnostic at the Joint European Torus (JET) provides measurements of the impurity ion temperature T(i), toroidal velocity V(phi), and impurity ion densities n(imp), across the whole minor radius. A contribution to the uncertainty of the measured quantities is the error resulting from the multi-Gaussian fit and photon statistics, usually quoted for each measured data. Absolute intensity calibration and especially alignment of the viewing directions can introduce an important systematic error. The technique adopted at JET to reduce this systematic contribution to the error is presented in this paper. The error in T(i), V(phi), and n(imp) is then discussed depending on their use.

  14. Design of charge exchange recombination spectroscopy for the joint Texas experimental tokamak.

    PubMed

    Chi, Y; Zhuang, G; Cheng, Z F; Hou, S Y; Cheng, C; Li, Z; Wang, J R; Wang, Z J

    2014-11-01

    The old diagnostic neutral beam injector first operated at the University of Texas at Austin is ready for rejoining the joint Texas experimental tokamak (J-TEXT). A new set of high voltage power supplies has been equipped and there is no limitation for beam modulation or beam pulse duration henceforth. Based on the spectra of fully striped impurity ions induced by the diagnostic beam the design work for toroidal charge exchange recombination spectroscopy (CXRS) system is presented. The 529 nm carbon VI (n = 8 - 7 transition) line seems to be the best choice for ion temperature and plasma rotation measurements and the considered hardware is listed. The design work of the toroidal CXRS system is guided by essential simulation of expected spectral results under the J-TEXT tokamak operation conditions.

  15. Molecular (Feshbach) treatment of charge exchange Li/sup 3 +/+He collisions. I. Energies and couplings

    SciTech Connect

    Martin, F.; Riera, A.; Yanez, M.

    1986-05-15

    We point out a fundamental difference between the molecular treatment of charge exchange X/sup n/++H(1s) and X/sup n/++He(1s/sup 2/) collisions, which is that the latter process involves molecular states that are formally autoionizing. Then standard ab initio methods do not, in general, yield the relevant wave functions that are needed in the collision treatment, irrespective of whether quasimolecular autoionization be significant or not during the collision. We implement a particularly simple and useful form of the Feshbach formalism to calculate the energies of those two electron systems, and a method to evaluate the corresponding dynamical couplings is presented for the first time. Our implementation of this formalism together with the new computational techniques involved are presented in detail.

  16. Creation of recognition sites for organophosphate esters based on charge transfer and ligand exchange imprinting methods.

    PubMed

    Say, Ridvan

    2006-10-01

    This manuscript describes a method for the selective binding behavior of paraoxan and parathion compounds on surface imprinted polymers which were prepared using both charge transfer (CT) (methacryloyl-antipyrine, MAAP) and ligand-exchange (LE) (methacryloyl-antipyrine-gadalonium, MAAP-Gd) monomers. These polymers were prepared in the presence of azobisisobutyronitrile (AIBN) as an initiator and crosslinking EDMA and were imprinted with organophosphate esters. Influence of CT and LE imprinting on the creation of recognition sites toward paraoxan and parathion was determined applying adsorption isotherms. The effect of initial concentration of paraoxan and parathion, adsorption time and imprinting efficiency on adsorption selectivity for MIP-CT and MIP-LE was investigated. Association constant (K(ass)), number of accessible sites (Q(max)), relative selectivity coefficient (k') and binding ability were also evaluated.

  17. Wave packet methods for charge exchange processes in ion-atom collisions

    NASA Astrophysics Data System (ADS)

    Baloı̈tcha, E.; Desouter-Lecomte, M.; Bacchus-Montabonel, M.-C.; Vaeck, N.

    2001-05-01

    The efficiency of different time-independent and time-dependent wave packet methods to calculate charge-exchange cross sections is discussed. The time-independent spectral projection method is based on the Chebyshev expansion of the resolvent function and represents an interesting alternative to the usual Fourier method which involves a time propagation. On the other hand, the flux operator method still requires propagation in time but uses the properties of absorbing potentials in order to calculate the flux operator matrix elements. We show the necessity of introducing the appropriate Hankel-Riccati functions when the full Hamiltonian contains a centrifugal term in 1/R2 in order to reduce the computational time. The collisional system Si4++He is studied as a test case.

  18. Scaling for state-selective charge exchange due to collisions of multicharged ions with hydrogen

    NASA Astrophysics Data System (ADS)

    Jorge, A.; Illescas, Clara; Miraglia, J. E.; Gravielle, M. S.

    2015-12-01

    In this article we evaluate state-resolved charge exchange cross sections for Be{}4+, {{{B}}}5+, {{{C}}}6+, {{{N}}}7+, and {{{O}}}8+ projectiles colliding with atomic hydrogen employing two different methods: the classical trajectory Monte Carlo and the eikonal impulse approximations. These cross sections are used to extend previously derived scaling laws for n-, nl-, and nlm-distributions to highly excited final levels with 4≤slant n≤slant 9, covering energies in the range 50-2000 {{keV}}/ amu. Present total and partial capture cross sections are in agreement with available experimental and theoretical data for these collision systems. Besides, the proposed scaling rules are also verified by other theories, becoming a useful instrument for plasma research.

  19. Scaling for state-selective charge exchange due to collisions of multicharged ions with hydrogen

    NASA Astrophysics Data System (ADS)

    Jorge, A.; Illescas, Clara; Miraglia, J. E.; Gravielle, M. S.

    2014-12-01

    In this article we evaluate state-resolved charge exchange cross sections for Be{}4+, {{{B}}}5+, {{{C}}}6+, {{{N}}}7+, and {{{O}}}8+ projectiles colliding with atomic hydrogen employing two different methods: the classical trajectory Monte Carlo and the eikonal impulse approximations. These cross sections are used to extend previously derived scaling laws for n-, nl-, and nlm-distributions to highly excited final levels with 4≤slant n≤slant 9, covering energies in the range 50-2000 {{keV}}/ amu. Present total and partial capture cross sections are in agreement with available experimental and theoretical data for these collision systems. Besides, the proposed scaling rules are also verified by other theories, becoming a useful instrument for plasma research.

  20. Inelastic Scattering and Single and Double Charge Exchange Reactions Within the A=27 Isobaric Multiplet.

    NASA Astrophysics Data System (ADS)

    McKinzie, Matthew Gordon

    1995-01-01

    Angular distributions for the reactions ^{27}Al, ^{28 }Si(pi^{+/- },pi^{+/-} ) at T_pi = 180 MeV and an excitation function at theta_ {rm lab.} = 5^{ rm o} for the reaction ^{27}Al(pi^{+}, pi^{-})^{27}P were measured using the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility in Los Alamos, New Mexico. Angular distributions for the reaction ^{27}Al(n,p)^ {27}Mg were measured at T_ {rm N} = 198 MeV using the Medium Resolution Spectrometer at Canada's Tri-University Meson Facility in Vancouver, British Columbia. Multipole matrix elements were extracted in a macroscopic manner from the pion inelastic angular distributions using the distorted-wave impulse approximation and collective -model transition densities. Microscopic calculations of these extracted matrix elements and of the pion angular distributions were examined. Double charge exchange (DCX) excitation functions to the ^{27}P ground state and an excited state were measured at nine incident pion energies from T_pi = 100 to 293.4 MeV. The systematics of DCX excitation functions to low-lying states is reviewed in light of these data. Microscopic calculations of DCX for and near A = 27 are investigated. Double giant resonances in ^{27}P were observed at the three highest energies. The (n,p) charge exchange angular distributions were obtained for theta_{rm lab.} = 0^circ, 4^circ, 8^ circ, 12^circ, 18^circ and 24^ circ. The Gamow-Teller strength distribution was measured and compared to a microscopic calculation. The constant of proportionality between reduced transition probability and cross section (the unit cross section) was generalized and examined for configuration dependence. Data for higher spin-multipole isovector excitations are presented, including low-lying spin-isospin E2 strength and negative -parity giant resonances.

  1. Kinetic theory and atomic physics corrections for determination of ion velocities from charge-exchange spectroscopy

    NASA Astrophysics Data System (ADS)

    Muñoz Burgos, J. M.; Burrell, K. H.; Solomon, W. M.; Grierson, B. A.; Loch, S. D.; Ballance, C. P.; Chrystal, C.

    2013-09-01

    Charge-exchange spectroscopy is a powerful diagnostic tool for determining ion temperatures, densities and rotational velocities in tokamak plasmas. This technique depends on detailed understanding of the atomic physics processes that affect the measured apparent velocities with respect to the true ion rotational velocities. These atomic effects are mainly due to energy dependence of the charge-exchange cross-sections, and in the case of poloidal velocities, due to gyro-motion of the ion during the finite lifetime of the excited states. Accurate lifetimes are necessary for correct interpretation of measured poloidal velocities, specially for high density plasma regimes on machines such as ITER, where l-mixing effects must be taken into account. In this work, a full nl-resolved atomic collisional radiative model coupled with a full kinetic calculation that includes the effects of electric and magnetic fields on the ion gyro-motion is presented for the first time. The model directly calculates from atomic physics first principles the excited state lifetimes that are necessary to evaluate the gyro-orbit effects. It is shown that even for low density plasmas where l-mixing effects are unimportant and coronal conditions can be assumed, the nl-resolved model is necessary for an accurate description of the gyro-motion effects to determine poloidal velocities. This solution shows good agreement when compared to three QH-mode shots on DIII-D, which contain a wide range of toroidal velocities and high ion temperatures where greater atomic corrections are needed. The velocities obtained from the model are compared to experimental velocities determined from co- and counter-injection of neutral beams on DIII-D.

  2. Wall reflection modeling for charge exchange recombination spectroscopy (CXRS) measurements on Textor and ITER

    NASA Astrophysics Data System (ADS)

    Banerjee, Santanu; Vasu, P.; von Hellermann, M.; Jaspers, R. J. E.

    2010-12-01

    Contamination of optical signals by reflections from the tokamak vessel wall is a matter of great concern. For machines such as ITER and future reactors, where the vessel wall will be predominantly metallic, this is potentially a risk factor for quantitative optical emission spectroscopy. This is, in particular, the case when bremsstrahlung continuum radiation from the bulk plasma is used as a common reference light source for the cross-calibration of visible spectroscopy. In this paper the reflected contribution to the continuum level in Textor and ITER has been estimated for the detection channels meant for charge exchange recombination spectroscopy (CXRS). A model assuming diffuse reflection has been developed for the bremsstrahlung which is a much extended source. Based on this model, it is shown that in the case of ITER upper port 3, a wall with a moderate reflectivity of 20% leads to the wall reflected fraction being as high as 55-60% of the weak signals in the edge channels. In contrast, a complete bidirectional reflectance distribution function (BRDF) based model has been developed in order to estimate the reflections from more localized sources like the charge exchange (CX) emission from a neutral beam in tokamaks. The largest signal contamination of ~15% is seen in the core CX channels, where the true CX signal level is much lower than that in the edge channels. Similar values are obtained for Textor also. These results indicate that the contributions from wall reflections may be large enough to significantly distort the overall spectral features of CX data, warranting an analysis at different wavelengths.

  3. Radiation reaction and pitch-angle changes for a charge undergoing synchrotron losses

    NASA Astrophysics Data System (ADS)

    Singal, Ashok K.

    2016-05-01

    In the derivation of synchrotron radiation formulae, it has been assumed that the pitch angle of a charge remains constant during the radiation process. However, from the radiation reaction formula, while the component of the velocity vector perpendicular to the magnetic field reduces in magnitude due to radiative losses, the parallel component does not undergo any change during radiation. Therefore, there is a change in the ratio of the two components, implying a change in the pitch angle. We derive the exact formula for the change in energy of radiating electrons by taking into account the change of the pitch angle due to radiative losses. From this, we derive the characteristic decay time of synchrotron electrons over which they turn from highly relativistic into mildly relativistic ones.

  4. What can be Learned from X-ray Spectroscopy Concerning Hot Gas in Local Bubble and Charge Exchange Processes?

    NASA Technical Reports Server (NTRS)

    Snowden, Steve

    2007-01-01

    What can be learned from x-ray spectroscopy in observing hot gas in local bubble and charge exchange processes depends on spectral resolution, instrumental grasp, instrumental energy band, signal-to-nose, field of view, angular resolution and observatory location. Early attempts at x-ray spectroscopy include ROSAT; more recently, astronomers have used diffuse x-ray spectrometers, XMM Newton, sounding rocket calorimeters, and Suzaku. Future observations are expected with calorimeters on the Spectrum Roentgen Gamma mission, and the Solar Wind Charge Exchange (SWCX). The Geospheric SWCX may provide remote sensing of the solar wind and magnetosheath and remote observations of solar CMEs moving outward from the sun.

  5. Calculations on charge state and energy loss of argon ions in partially and fully ionized carbon plasmas.

    PubMed

    Barriga-Carrasco, Manuel D; Casas, David; Morales, Roberto

    2016-03-01

    The energy loss of argon ions in a target depends on their velocity and charge density. At the energies studied in this work, it depends mostly on the free and bound electrons in the target. Here the random-phase approximation is used for analyzing free electrons at any degeneracy. For the plasma-bound electrons, an interpolation between approximations for low and high energies is applied. The Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its equilibrium charge state Q(eq). This latter criterion implies that the equilibrium charge state depends slightly on the electron density and temperature of the plasma. On the other hand, the effective charge Q(eff) is obtained as the ratio between the energy loss of the argon ion and that of the proton for the same plasma conditions. This effective charge Q(eff) is larger than the equilibrium charge state Q(eq) due to the incorporation of the BK charge distribution. Though our charge-state estimations are not exactly the same as the experimental values, our energy loss agrees quite well with the experiments. It is noticed that the energy loss in plasmas is higher than that in the same cold target of about, ∼42-62.5% and increases with carbon plasma ionization. This confirms the well-known enhanced plasma stopping. It is also observed that only a small part of this energy loss enhancement is due to an increase of the argon charge state, namely only ∼2.2 and 5.1%, for the partially and the fully ionized plasma, respectively. The other contribution is connected with a better energy transfer to the free electrons at plasma state than to the bound electrons at solid state of about, ∼38.8-57.4%, where higher values correspond to a fully ionized carbon plasma. PMID:27078472

  6. Compact formulae, dynamics and radiation of charged particles under synchro-curvature losses

    NASA Astrophysics Data System (ADS)

    Viganò, Daniele; Torres, Diego F.; Hirotani, Kouichi; Pessah, Martín E.

    2015-02-01

    We consider the fundamental problem of charged particles moving along and around a curved magnetic field line, revising the synchro-curvature radiation formulae introduced by Cheng & Zhang. We provide more compact expressions to evaluate the spectrum emitted by a single particle, identifying the key parameter that controls the transition between the curvature-dominated and the synchrotron-dominated regime. This parameter depends on the local radius of curvature of the magnetic field line, the gyration radius, and the pitch angle. We numerically solve the equations of motion for the emitting particle by considering self-consistently the radiative losses, and provide the radiated spectrum produced by a particle when an electric acceleration is balanced by its radiative losses, as it is assumed to happen in the outer gaps of pulsar's magnetospheres. We compute the average spectrum radiated throughout the particle trajectory finding that the slope of the spectrum before the peak depends on the location and size of the emission region. We show how this effect could then lead to a variety of synchro-curvature spectra. Our results reinforce the idea that the purely synchrotron or curvature losses are, in general, inadequate to describe the radiative reaction on the particle motion, and the spectrum of emitted photons. Finally, we discuss the applicability of these calculations to different astrophysical scenarios.

  7. The Measurement of Pion Double Charge Exchange on CARBON-13, CARBON-14, MAGNESIUM-26 and IRON-56.

    NASA Astrophysics Data System (ADS)

    Seidl, Peter Anthony

    Cross sections for the ('13,14)C,('26)Mg,('56)Fe((pi)('+),(pi)(' -))('13,14)O,('26)Si,('56)Ni reactions were measured with the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility for 120 (LESSTHEQ) T(,(pi)) (LESSTHEQ) 292 MeV and 0 (LESSTHEQ) (theta) (LESSTHEQ) 50. The double isobaric analog states (DIAS) were of primary interest, and in addition, cross sections for transitions to ('14)O(0('+), 5.92 MeV), ('14)O(2('+), 7.77 MeV), ('56)Ni(gs), ('13)O(gs), and ('13)O(4.21 MeV) are presented. The ('13)O(4.21 MeV) state is postulated to have J('(pi)) = 1/2('-). The data are compared to previously measured double-charge -exchange cross sections on other nuclei, and the systematics of double charge exchange on T (GREATERTHEQ) 1 target nuclei leading to DIAS are studied. Near the (DELTA)(,33) resonance, cross section for the DIAS transitions are in disagreement with calculations in which the reaction is treated as sequential charge exchange through the free pion-nucleon amplitude, while for T(,(pi)) > 200 MeV the anomalous features of the 164 MeV data are not apparent. This is evidence for significant higher order contributions to the double-charge -exchange amplitude near the resonance energy. Two theoretical approaches that include two nucleon processes are applied to the DIAS data.

  8. Analysis of the Charge Exchange Between the Human Body and Ground: Evaluation of “Earthing” From an Electrical Perspective

    PubMed Central

    Chamberlin, Kent; Smith, Wayne; Chirgwin, Christopher; Appasani, Seshank; Rioux, Paul

    2014-01-01

    Objective The purpose of this study was to investigate “earthing” from an electrical perspective through measurement and analysis of the naturally occurring electron flow between the human body or a control and ground as this relates to the magnitude of the charge exchange, the relationship between the charge exchange and body functions (respiration and heart rate), and the detection of other information that might be contained in the charge exchange. Methods Sensitive, low-noise instrumentation was designed and fabricated to measure low-level current flow at low frequencies. This instrumentation was used to record current flow between human subjects or a control and ground, and these measurements were performed approximately 40 times under varied circumstances. The results of these measurements were analyzed to determine if information was contained in the current exchange. Results The currents flowing between the human body and ground were small (nanoamperes), and they correlated with subject motion. There did not appear to be any information contained in this exchange except for information about subject motion. Conclusions This study showed that currents flow between the environment (earth) and a grounded human body; however, these currents are small (nanoamperes) and do not appear to contain information other than information about subject motion. PMID:25435837

  9. Observation and modeling of geocoronal charge exchange X-ray emission during solar wind gusts

    SciTech Connect

    Wargelin, B. J.; Kornbleuth, M.; Juda, M.; Martin, P. L.

    2014-11-20

    Solar wind charge exchange (SWCX) X-rays are emitted when highly charged solar wind ions such as O{sup 7{sup +}} collide with neutral gas, including the Earth's tenuous outer atmosphere (exosphere or geocorona) and hydrogen and helium from the local interstellar medium drifting through the heliosphere. This geocoronal and heliospheric emission comprises a significant and varying fraction of the soft X-ray background (SXRB) and is seen in every X-ray observation, with the intensity dependent on solar wind conditions and observation geometry. Under the right conditions, geocoronal emission can increase the apparent SXRB by roughly an order of magnitude for an hour or more. In this work, we study a dozen occasions when the near-Earth solar wind flux was exceptionally high. These gusts of wind lead to abrupt changes in SWCX X-ray emission around Earth, which may or may not be seen by X-ray observatories depending on their line of sight. Using detailed three-dimensional magnetohydrodynamical simulations of the solar wind's interaction with the Earth's magnetosphere, and element abundances and ionization states measured by ACE, we model the time-dependent brightness of major geocoronal SWCX emission lines during those gusts and compare with changes in the X-ray background measured by the Chandra X-ray Observatory. We find reasonably good agreement between model and observation, with measured geocoronal line brightnesses averaged over 1 hr of up to 136 photons s{sup –1} cm{sup –2} sr{sup –1} in the O VII Kα triplet around 564 eV.

  10. Charge carrier loss mechanisms in CuInS2/ZnO nanocrystal solar cells.

    PubMed

    Scheunemann, Dorothea; Wilken, Sebastian; Parisi, Jürgen; Borchert, Holger

    2016-06-28

    Heterojunction solar cells based on colloidal nanocrystals (NCs) have shown remarkable improvements in performance in the last decade, but this progress is limited to merely two materials, PbS and PbSe. However, solar cells based on other material systems such as copper-based compounds show lower power conversion efficiencies and much less effort has been made to develop a better understanding of factors limiting their performance. Here, we study charge carrier loss mechanisms in solution-processed CuInS2/ZnO NC solar cells by combining steady-state measurements with transient photocurrent and photovoltage measurements. We demonstrate the presence of an extraction barrier at the CuInS2/ZnO interface, which can be reduced upon illumination with UV light. However, trap-assisted recombination in the CuInS2 layer is shown to be the dominant decay process in these devices. PMID:27250665

  11. Ion-exchange and hydrophobic interactions affecting selectivity for neutral and charged solutes on three structurally similar agglomerated ion-exchange and mixed-mode stationary phases.

    PubMed

    Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett

    2013-11-25

    The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC - strong anion exchange, Thermo Fisher Scientific IonPac CS10--strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and ampholytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and ampholytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed logP values of 0.38-0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18

  12. Mechanistic modeling of ion-exchange process chromatography of charge variants of monoclonal antibody products.

    PubMed

    Kumar, Vijesh; Leweke, Samuel; von Lieres, Eric; Rathore, Anurag S

    2015-12-24

    Ion-exchange chromatography (IEX) is universally accepted as the optimal method for achieving process scale separation of charge variants of a monoclonal antibody (mAb) therapeutic. These variants are closely related to the product and a baseline separation is rarely achieved. The general practice is to fractionate the eluate from the IEX column, analyze the fractions and then pool the desired fractions to obtain the targeted composition of variants. This is, however, a very cumbersome and time consuming exercise. A mechanistic model that is capable of simulating the peak profile will be a much more elegant and effective way to make a decision on the pooling strategy. This paper proposes a mechanistic model, based on the general rate model, to predict elution peak profile for separation of the main product from its variants. The proposed approach uses inverse fit of process scale chromatogram for estimation of model parameters using the initial values that are obtained from theoretical correlations. The packed bed column has been modeled along with the chromatographic system consisting of the mixer, tubing and detectors as a series of dispersed plug flow and continuous stirred tank reactors. The model uses loading ranges starting at 25% to a maximum of 70% of the loading capacity and hence is applicable to process scale separations. Langmuir model has been extended to include the effects of salt concentration and temperature on the model parameters. The extended Langmuir model that has been proposed uses one less parameter than the SMA model and this results in a significant ease of estimating the model parameters from inverse fitting. The proposed model has been validated with experimental data and has been shown to successfully predict peak profile for a range of load capacities (15-28mg/mL), gradient lengths (10-30CV), bed heights (6-20cm), and for three different resins with good accuracy (as measured by estimation of residuals). The model has been also

  13. Mechanistic modeling of ion-exchange process chromatography of charge variants of monoclonal antibody products.

    PubMed

    Kumar, Vijesh; Leweke, Samuel; von Lieres, Eric; Rathore, Anurag S

    2015-12-24

    Ion-exchange chromatography (IEX) is universally accepted as the optimal method for achieving process scale separation of charge variants of a monoclonal antibody (mAb) therapeutic. These variants are closely related to the product and a baseline separation is rarely achieved. The general practice is to fractionate the eluate from the IEX column, analyze the fractions and then pool the desired fractions to obtain the targeted composition of variants. This is, however, a very cumbersome and time consuming exercise. A mechanistic model that is capable of simulating the peak profile will be a much more elegant and effective way to make a decision on the pooling strategy. This paper proposes a mechanistic model, based on the general rate model, to predict elution peak profile for separation of the main product from its variants. The proposed approach uses inverse fit of process scale chromatogram for estimation of model parameters using the initial values that are obtained from theoretical correlations. The packed bed column has been modeled along with the chromatographic system consisting of the mixer, tubing and detectors as a series of dispersed plug flow and continuous stirred tank reactors. The model uses loading ranges starting at 25% to a maximum of 70% of the loading capacity and hence is applicable to process scale separations. Langmuir model has been extended to include the effects of salt concentration and temperature on the model parameters. The extended Langmuir model that has been proposed uses one less parameter than the SMA model and this results in a significant ease of estimating the model parameters from inverse fitting. The proposed model has been validated with experimental data and has been shown to successfully predict peak profile for a range of load capacities (15-28mg/mL), gradient lengths (10-30CV), bed heights (6-20cm), and for three different resins with good accuracy (as measured by estimation of residuals). The model has been also

  14. Thermal Energy Exchange Model and Water Loss of a Barrel Cactus, Ferocactus acanthodes1

    PubMed Central

    Lewis, Donald A.; Nobel, Park S.

    1977-01-01

    The influences of various diurnal stomatal opening patterns, spines, and ribs on the stem surface temperature and water economy of a CAM succulent, the barrel cactus Ferocactus acanthodes, were examined using an energy budget model. To incorporate energy exchanges by shortwave and longwave irradiation, latent heat, conduction, and convection as well as the heat storage in the massive stem, the plant was subdivided into over 100 internal and external regions in the model. This enabled the average surface temperature to be predicted within 1 C of the measured temperature for both winter and summer days. Reducing the stem water vapor conductance from the values observed in the field to zero caused the average daily stem surface temperature to increase only 0.7 C for a winter day and 0.3 C for a summer day. Thus, latent heat loss does not substantially reduce stem temperature. Although the surface temperatures averaged 18 C warmer for the summer day than for the winter day for a plant 41 cm tall, the temperature dependence of stomatal opening caused the simulated nighttime water loss rates to be about the same for the 2 days. Spines moderated the amplitude of the diurnal temperature changes of the stem surface, since the daily variation was 17 C for the winter day and 25 C for the summer day with spines compared with 23 C and 41 C, respectively, in their simulated absence. Ribs reduced the daytime temperature rise by providing 54% more area for convective heat loss than for a smooth circumscribing surface. In a simulation where both spines and ribs were eliminated, the daytime average surface temperature rose by 5 C. PMID:16660148

  15. Energy loss of tens keV charged particles traveling in the hot dense carbon plasma

    NASA Astrophysics Data System (ADS)

    Fu, ZhenGuo; Wang, ZhiGang; He, Bin; Li, DaFang; Zhang, Ping

    2016-08-01

    The energy loss of charged particles, including electrons, protons, and α-particles with tens keV initial energy E 0, traveling in the hot dense carbon (C) plasma for densities from 2.281 to 22.81 g/cm3 and temperatures from 400 to 1500 eV is systematically and quantitatively studied by using the dimensional continuation method. The behaviors of different charged particles are readily distinguishable from each other. Firstly, because an ion is thousands times heavier than an electron, the penetration distance of the electron is much longer than that of proton and α-particle traveling in the plasma. Secondly, most energy of electron projectile with E 0 < 100 keV deposits into the electron species of C plasma, while for the cases of proton and α-particle with E 0 < 100 keV, about more than half energy transfers into the ion species of C plasma. A simple decreasing law of the penetration distance as a function of the plasma density is fitted, and different behaviors of each projectile particle can be clearly found from the fitted data. We believe that with the advanced progress of the present experimental technology, the findings shown here could be confirmed in ion-stopping experiments in the near future.

  16. Analysis of isomeric polycyclic aromatic hydrocarbons by charge-exchange chemical ionization mass spectrometry

    SciTech Connect

    Simonsick, W.J. Jr.; Hites, R.A.

    1984-12-01

    Charge-exchange chemical ionization mass spectrometry (using a 15% mixture of methane in argon) yields abundant M/sup +/, M + H/sup +/, M + C/sub 2/H/sub 5//sup +/ ions of polycyclic aromatic hydrocarbons (PAH). On the basis of the relative intensities of the M + H/sup +/ ion to the M/sup +/ ion, this technique can differentiate, in a predictable manner, isomeric structures of PAH. The operating conditions were evaluated and optimized; the most significant contributions to the variations in the (M + H)/sup +//M/sup +/ ratios are the temperature, pressure, and condition of the ion source. The optimum ion source temperature (250/sup 0/C) and pressure (0.8 torr) are easily controlled and regulated. The variable contamination of the ion source is compensated by an internal standard 1,2,3,5-tetrafluorobenzene. The analyses of Standard Reference Materials 1648 and 1649 (air particulate samples) and a carbon black extract are reported. Triphenylene and chrysene, although not chromatographically resolved, can be quantitated by using this technique. The identification of acephenanthrylene based on the measurement of ratios and calculated ionization potentials is also presented.

  17. Charge-exchange Induced Modulation of the Heliosheath Ion Distribution Downstream of the Termination Shock

    NASA Astrophysics Data System (ADS)

    Fahr, H. J.; Fichtner, H.; Scherer, K.

    2015-12-01

    We consider the evolution of the solar wind ion distribution function alongthe plasma flow downstream from the termination shock induced by chargeexchange processes with cold interstellar H-atoms. We start from a kineticphase space transport equation valid in the bulk frame of the plasma flowthat takes into account convective changes, cooling processes, energydiffusion and ion injection, and describes solar wind and pick-up ionsas a co-moving, isotropic, joint ion population. From this kinetic transportequation one can ascend to an equation for the pressure moment of the iondistribution function, a so-called pressure transport equation, describingthe evolution of the ion pressure in the comoving rest frame. Assuming thatthe local ion distribution can be represented by an adequate kappa functionwith a kappa parameter that varies with the streamline coordinate, weobtain an ordinary differential equation for kappa as function of thestreamline coordinate s. With this result then we gain the heliosheath iondistribution function downstream of the termination shock. The latter thencan be used to predict the Voyager-2 measured moments of the distributionfunction like ion density and ion temperature, and it can also be used topredict spectral fluxes of ENA`s originating from these ions and registeredby IBEX-Hi and IBEX-Lo.We especially analyse the solar wind ion temperature decreasemeasured by Voyager-2 between the years 2008 to 2011 and try to explain itas a charge-exchange induced cooling of the ion distribution function duringthe associated ion convection period.

  18. CAN CHARGE EXCHANGE EXPLAIN ANOMALOUS SOFT X-RAY EMISSION IN THE CYGNUS LOOP?

    SciTech Connect

    Cumbee, R. S.; Henley, D. B.; Stancil, P. C.; Shelton, R. L.; Nolte, J. L.; Wu, Y.; Schultz, D. R.

    2014-06-01

    Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this ''anomalously'' enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of O{sup 8} {sup +}, O{sup 7} {sup +}, N{sup 7} {sup +}, N{sup 6} {sup +}, C{sup 6} {sup +}, and C{sup 5} {sup +} with H with an energy of 1 keV u{sup –1} (438 km s{sup –1}). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically O{sup 7} {sup +} + H, does provide for a statistically significant improvement over a pure shock model.

  19. Temperatures of individual ion species and heating due to charge exchange in the ionosphere of Venus

    NASA Technical Reports Server (NTRS)

    Kim, Jhoon; Nagy, Andrew F.; Cravens, Thomas E.; Shinagawa, Hiroyuki

    1990-01-01

    The coupled electron and multispecies ion energy equations were solved for daytime conditions in the Venus ionosphere. The heating rates due to charge exchange between hot oxygen atoms and thermal oxygen ions were calculated and incorporated into the energy equations. The combination of the traditional EUV heating and this hot oxygen energy source leads to calculated electron and individual ion temperatures significantly lower than the measured values during solar cycle maximum conditions. Calculations were also carried out for solar cycle minimum conditions, which led to considerably lower temperatures; no data are available which would allow direct comparisons of these results with measurements. In order to obtain calculated temperature values consistent with the observed ones, for solar cycle maximum conditions, topside heat inflows into the ion and electron gases have to be introduced or the thermal conductivity must be reduced by considering the effect of steady and fluctuating magnetic fields, as was done in previous studies. The addition of hot oxygen heating leads to minor increases in the calculated ion temperatures except for the case of reduced thermal conductivities. Separate temperatures were calculated for each ion species for a number of different conditions and in general the differences were found to be relatively small.

  20. Possible Charge Exchange X-Ray Emission from the Cygnus Loop detected with Suzaku

    NASA Astrophysics Data System (ADS)

    Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Petre, Robert; Hwang, Una; Hewitt, John

    We present results of a spatially-resolved X-ray spectral analysis of nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that some of the spectra show a bump at ˜0.7 keV as a "shoulder" of the lines at ˜0.66 keV which is a combination of O H Lyα and O Heβ. The regions showing the "shoulder" is confined within narrow (< a few arcmin) regions behind the shock at position angles of 0-40, 110-160, and 270-330 degrees measured from north over east. Around the rim, the position angles where the X-ray excess is present correspond to relatively weak radio emission as well as optical emission from non-radiative Hα filaments. While other possibilities (e.g., Fe L emission) cannot be fully excluded, these correlations lead us to consider that the "shoulder" may be O Heγ + δ + etc lines produced by charge exchange between H-like O ions and neutral H. Whatever its origin, the "shoulder" significantly affects the spectral analysis; the best-fit parameters strongly depend on whether or not we include the "shoulder" in the spectral fitting. We will discuss this issue in terms of our previous results of our spectral analysis for the rim regions.

  1. Suzaku and XMM-Newton observations of the North Polar Spur: Charge exchange or ISM absorption?

    NASA Astrophysics Data System (ADS)

    Gu, Liyi; Mao, Junjie; Costantini, Elisa; Kaastra, Jelle

    2016-10-01

    By revisiting the Suzaku and XMM-Newton data of the North Polar Spur, we discovered that the spectra are inconsistent with the traditional model consisting of pure thermal emission and neutral absorption. The most prominent discrepancies are the enhanced O vii and Ne ix forbidden-to-resonance ratios, and a high O viii Lyβ line relative to other Lyman series. A collisionally ionized absorption model can naturally explain both features, while a charge exchange component can only account for the former. By including the additional ionized absorption, the plasma in the North Polar Spur can be described by a single-phase collisional ionization equilibrium (CIE) component with a temperature of 0.25 keV, and nitrogen, oxygen, neon, magnesium, and iron abundances of 0.4-0.8 solar. The abundance pattern of the North Polar Spur is well in line with those of the Galactic halo stars. The high nitrogen-to-oxygen ratio reported in previous studies can be migrated to the large transmission of the O viii Lyα line. The ionized absorber is characterized by a balance temperature of 0.17-0.20 keV and a column density of 3-5 × 1019 cm-2. Based on the derived abundances and absorption, we speculate that the North Polar Spur is a structure in the Galactic halo, so that the emission is mostly absorbed by the Galactic interstellar medium in the line of sight.

  2. Feasibility of non-thermal helium measurements with charge exchange spectroscopy on ITER

    NASA Astrophysics Data System (ADS)

    Kappatou, A.; Delabie, E.; Jaspers, R. J. E.; von Hellermann, M. G.

    2012-04-01

    The use of active charge exchange recombination spectroscopy (CXRS) as a diagnostic for fusion-produced alpha particles on ITER is constrained by the signal-to-noise ratio, which is determined by the intensity of the line of interest, the optical throughput of the diagnostic, the neutral beam penetration, and the intensity of bremsstrahlung radiation. The CX spectral line for fast ions has been modelled together with the expected background emission and we present the signal-to-noise ratios calculated as a function of the diagnostic design parameters. Combining the CXRS data from both the heating and the diagnostic neutral beams on ITER, information on fast ions with energies up to 1 MeV can be obtained for the parameters of the ITER core CXRS diagnostic design. To achieve this, energy binning of the signal is used (100 keV bins or larger), in order to improve the signal-to-noise ratio, with a time resolution of 2 s. The time resolution of the measurement can be improved using a higher throughput spectrometer, but this is ultimately limited by the amount of light from the neutral beam that can be collected. Despite the challenges and the fact that the results are not as optimistic as previously assumed, it is concluded that useful information on fast helium density profiles can be obtained using CXRS on ITER.

  3. X-ray emission from charge exchange in the Cygnus Loop SNR

    NASA Astrophysics Data System (ADS)

    Roberts, Shawn R.; Wang, Q. Daniel

    2015-05-01

    The Cygnus Loop has been the focus of substantial debate concerning the contribution of charge exchange (CX) to supernova remnant (SNR) X-ray emission. We take advantage of a distinct feature of CX, enhanced Kα forbidden line emission, and employ the energy centroid of the O VII Kα triplet as a diagnostic. Based on X-ray spectra extracted from an extensive set of Suzaku observations, we measure the energy centroid shifts of the triplet on and off the shock rim of the remnant. We find that enhanced forbidden to resonance line emission exists throughout much of the rim and this enhancement azimuthally correlates with non-radiative Hα filaments, a tracer of strong neutral-plasma interaction in the optical. We also show that alternative mechanisms cannot explain the observed enhancement. These results demonstrate the need to model the CX contribution to the X-ray emission of SNRs, particularly for shocks propagating in a partially neutral medium. Such modelling may be critically important to the correct measurements of the ionization, thermal, and chemical properties of SNRs.

  4. Integrated-Optic Wavelength Multiplexer In Glass Fabricated By A Charge Controlled Ion Exchange

    NASA Astrophysics Data System (ADS)

    Klein, R.; Jestel, D.; Lilienhof, H. J.; Rottman, F.; Voges, E.

    1989-02-01

    Integrated-optic wavelength division multiplexing (WDM) is commonly used in communication systems. These WDM-devices are also well suited to build up optical fiber networks for both intensity and interferometric sensor types. The operation principle of our wavelength division multiplexing devise is based on the wavelength dependent two-mode interference in a two-moded waveguide, which is coupled adiabatically to the single-mode input and output strip waveguides. The single-mode input and output waveguides are connected via two Y-branches ( "'kJ- 1° branching angle ) with a two-moded intersection region. The ratio of the light powers in the single-mode output waveguides depends on wavelength . The two-mode interference within the two-moded center waveguide leads to an almost wavelength periodic transmission caracteristic . Dual-channel multiplexers/demultiplexers were fabricated by a charge controlled field assisted pottasium exchange in B-270 glass (Desag). The devices have a typical channel separation of 30 - 40 nm and a far-end crosstalk attenuation of better than 16 dB. The operation wavelength regions of the fabricated devices are 0.6 - 0.8 µm and 1.3 - 1.6 µm, respectively.

  5. Effect of charge regulation on steric mass-action equilibrium for the ion-exchange adsorption of proteins.

    PubMed

    Shen, Hong; Frey, Douglas D

    2005-06-24

    A thermodynamic formalism is developed for incorporating the effects of charge regulation on the ion-exchange adsorption of proteins under mass-overloaded conditions as described by the steric mass-action (SMA) isotherm. To accomplish this, the pH titration behavior of a protein and the associated adsorption equilibrium of the various charged forms of a protein are incorporated into a model which also accounts for the steric hindrance of salt counterions caused by protein adsorption. For the case where the protein is dilute, the new model reduces to the protein adsorption model described recently by the authors which accounts for charge regulation. Similarly, the new model reduces to the steric mass-action isotherm developed by Brooks and Cramer which applies to mass-overloaded conditions for the case where charge regulation is ignored so that the protein has a fixed charge. Calculations using the new model were found to agree with experimental data for the adsorption of bovine serum albumin (BSA) on an anion-exchange column packing when using reasonable physical properties. The new model was also used to develop an improved theoretical criterion for determining the conditions required for an adsorbed species to displace a protein in displacement chromatography when the pH is near the protein pI.

  6. Protein adsorption on ion exchange resins and monoclonal antibody charge variant modulation.

    PubMed

    Guélat, Bertrand; Khalaf, Rushd; Lattuada, Marco; Costioli, Matteo; Morbidelli, Massimo

    2016-05-20

    A novel multicomponent adsorption equilibrium model for proteins on ion-exchange resins is developed on a statistical thermodynamic basis including surface coverage effects and protein-resin and protein-protein interactions. The resulting model exhibits a general competitive Langmuirian behavior and was applied to the study and optimization of the separation of monoclonal antibody charge variants on two strong cation exchangers. The model accounts explicitly for the effect of both pH and salt concentration, and its parameters can be determined in diluted conditions, that is, through physically sound assumptions, all model parameters can be obtained using solely experiments in diluted conditions, and be used to make predictions in overloaded conditions. The parameterization of the model and optimization of the separation is based on a two-step approach. First, gradient experiments in diluted conditions are undertaken in order to determine the model parameters. Based on these experiments and on information about the proteins of interest and the stationary phase used, all the model parameters can be estimated. Second, using the parameterized model, an initial Pareto optimization is undertaken where overloaded operating conditions are investigated. Experiments from this Pareto set are then used to refine the estimation of the model parameters. A second Pareto optimization can then be undertaken, this time with the refined parameters. This can be repeated until a satisfactory set of model parameters is found. This iterative approach is shown to be extremely efficient and to provide large amounts of knowledge based on only a few experiments. It is shown that due to the strong physical foundation of the model and the very low number of adjustable parameters, the number of iterations is expected to be at most two or three. Furthermore, the model based tool is improved as more experimental knowledge is provided, allowing for better estimations of the chromatographic

  7. Protein adsorption on ion exchange resins and monoclonal antibody charge variant modulation.

    PubMed

    Guélat, Bertrand; Khalaf, Rushd; Lattuada, Marco; Costioli, Matteo; Morbidelli, Massimo

    2016-05-20

    A novel multicomponent adsorption equilibrium model for proteins on ion-exchange resins is developed on a statistical thermodynamic basis including surface coverage effects and protein-resin and protein-protein interactions. The resulting model exhibits a general competitive Langmuirian behavior and was applied to the study and optimization of the separation of monoclonal antibody charge variants on two strong cation exchangers. The model accounts explicitly for the effect of both pH and salt concentration, and its parameters can be determined in diluted conditions, that is, through physically sound assumptions, all model parameters can be obtained using solely experiments in diluted conditions, and be used to make predictions in overloaded conditions. The parameterization of the model and optimization of the separation is based on a two-step approach. First, gradient experiments in diluted conditions are undertaken in order to determine the model parameters. Based on these experiments and on information about the proteins of interest and the stationary phase used, all the model parameters can be estimated. Second, using the parameterized model, an initial Pareto optimization is undertaken where overloaded operating conditions are investigated. Experiments from this Pareto set are then used to refine the estimation of the model parameters. A second Pareto optimization can then be undertaken, this time with the refined parameters. This can be repeated until a satisfactory set of model parameters is found. This iterative approach is shown to be extremely efficient and to provide large amounts of knowledge based on only a few experiments. It is shown that due to the strong physical foundation of the model and the very low number of adjustable parameters, the number of iterations is expected to be at most two or three. Furthermore, the model based tool is improved as more experimental knowledge is provided, allowing for better estimations of the chromatographic

  8. Charge-exchange measurements of MHD activity during neutral beam injection in the Princeton Large Torus and the Poloidal Divertor Experiment

    SciTech Connect

    Goldston, R.J.; Kaita, R.; Beiersdorfer, P.; Gammel, G.; Herndon, D.L.; McCune, D.C.; Meyerhofer, D.D.

    1986-07-01

    The horizontally scanning, multiangle charge-exchange analyzers on the Princeton Large Torus (PLT) and the Poloidal Divertor Experiment (PDX) were used to study the effects of MHD activity on the background ion distribution function and on the beam ion slowing-down process during high-power neutral injection. Sawtooth oscillations were observed in the fast ion flux on PLT and PDX, and measurements with neutral beams providing local neutral density enhancement indicate that ions are transported radially when these events occur. With near-perpendicular injection in PDX, at the lower toroidal fields necessary to maximize beta, rapid, repetitive bursts of greatly enhanced charge-exchange flux were observed. These are associated with the ''fishbone'' MHD instability, and a substantial depletion of the perpendicular slowing-down spectrum below the injection energy was seen. A simple phenomenological model for this loss mechanism was developed, and its use in simulation codes has been successful in providing good agreement with the data. The behavior and characteristics of this model are well matched by the direct theoretical calculations.

  9. Effects of exchanged cation and layer charge on the sorption of water and EGME vapors on montmorillonite clays

    USGS Publications Warehouse

    Chiou, C.T.; Rutherford, D.W.

    1997-01-01

    The effects of exchanged cation and layer charge on the sorption of water and ethylene glycol monoethyl ether (EGME) vapors on montmorillonite have been studied on SAz-1 and SWy-1 source clays, each exchanged respectively with Ca, Na, K, Cs and tetramethylammonium (TMA) cations. The corresponding lattice expansions were also determined, and the corresponding N2 adsorption data were provided for comparison. For clays exchanged with cations of low hydrating powers (such as K, Cs and TMA), water shows a notably lower uptake than does N2 at low relative pressures (P/P0). By contrast, EGME shows higher uptakes than N2 on all exchanged clays at all P/P0. The anomaly for water is attributed to its relatively low attraction for siloxane surfaces of montmorillonite because of its high cohesive energy density. In addition to solvating cations and expanding interlayers, water and EGME vapors condense into small clay pores and interlayer voids created by interlayer expansion. The initial (dry) interlayer separation varies more significantly with cation type than with layer charge; the water-saturated interlayer separation varies more with cation type than the EGME-saturated interlayer separation. Because of the differences in surface adsorption and interlayer expansion for water and EGME, no general correspondence is found between the isotherms of water and EGME on exchanged clays, nor is a simple relation observed between the overall uptake of either vapor and the cation solvating power. The excess interlayer capacities of water and of EGME that result from lattice expansion of the exchanged clays are estimated by correcting for amounts of vapor adsorption on planar clay surfaces and of vapor condensation into intrinsic clay pores. The resulting data follow more closely the relative solvating powers of the exchanged cations.

  10. Spectral Modeling of the Charge-exchange X-Ray Emission from M82

    NASA Astrophysics Data System (ADS)

    Zhang, Shuinai; Wang, Q. Daniel; Ji, Li; Smith, Randall K.; Foster, Adam R.; Zhou, Xin

    2014-10-01

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the Kα triplets of various He-like ions but also good fractions of the Lyα transitions of C VI (~87%), O VIII, and N VII (gsim50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 Å band originates in the CX. We infer an ion incident rate of 3 × 1051 s-1 undergoing CX at the hot and cool gas interface and an effective area of the interface of ~2 × 1045 cm2 that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  11. Neutrino and antineutrino charge-exchange reactions on {sup 12}C

    SciTech Connect

    Samana, A. R.; Krmpotic, F.; Paar, N.; Bertulani, C. A.

    2011-02-15

    We extend the formalism of weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture. Explicit violation of the conserved vector current hypothesis by the Coulomb field, as well as development of a sum-rule approach for inclusive cross sections, has been worked out. We have done a thorough study of exclusive (ground-state) properties of {sup 12}B and {sup 12}N within the projected quasiparticle random phase approximation (PQRPA). Good agreement with experimental data achieved in this way put into evidence the limitations of the standard RPA and QRPA models, which come from the inability of the RPA to open the p{sub 3/2} shell and from the nonconservation of the number of particles in the QRPA. The inclusive neutrino/antineutrino ({nu}/{nu}-tilde) reactions {sup 12}C({nu},e{sup -}){sup 12}N and {sup 12}C({nu}-tilde,e{sup +}){sup 12}B are calculated within both the PQRPA and the relativistic QRPA. It is found that (i) the magnitudes of the resulting cross sections are close to the sum-rule limit at low energy, but significantly smaller than this limit at high energies, for both {nu} and {nu}-tilde; (ii) they increase steadily when the size of the configuration space is augmented, particularly for {nu}/{nu}-tilde energies >200 MeV; and (iii) they converge for sufficiently large configuration space and final-state spin. The quasi-elastic {sup 12}C({nu},{mu}{sup -}){sup 12}N cross section recently measured in the MiniBooNE experiment is briefly discussed. We study the decomposition of the inclusive cross section based on the degree of forbiddenness of different multipoles. A few words are dedicated to the {nu}/{nu}-tilde-{sup 12}C charge-exchange reactions related to astrophysical applications.

  12. Solar Wind Charge Exchange Contribution to the ROSAT All Sky Survey Maps

    NASA Astrophysics Data System (ADS)

    Uprety, Y.; Chiao, M.; Collier, M. R.; Cravens, T.; Galeazzi, M.; Koutroumpa, D.; Kuntz, K. D.; Lallement, R.; Lepri, S. T.; Liu, W.; McCammon, D.; Morgan, K.; Porter, F. S.; Prasai, K.; Snowden, S. L.; Thomas, N. E.; Ursino, E.; Walsh, B. M.

    2016-10-01

    DXL (Diffuse X-ray emission from the Local Galaxy) is a sounding rocket mission designed to estimate the contribution of solar wind charge eXchange (SWCX) to the diffuse X-ray background and to help determine the properties of the Local Hot Bubble. The detectors are large area thin-window proportional counters with a spectral response that is similar to that of the PSPC used in the ROSAT All Sky Survey (RASS). A direct comparison of DXL and RASS data for the same part of the sky viewed from quite different vantage points in the solar system, and the assumption of approximate isotropy for the solar wind, allowed us to quantify the SWCX contribution to all six RASS bands (R1-R7, excluding R3). We find that the SWCX contribution at l=140^\\circ ,b=0^\\circ , where the DXL path crosses the Galactic plane, is 33 % +/- 6 % ({statistical})+/- 12 % ({systematic}) for R1, 44 % +/- 6 % +/- 5 % for R2, 18 % +/- 12 % +/- 11 % for R4, 14 % +/- 11 % +/- 9 % for R5, and negligible for the R6 and R7 bands. Reliable models for the distribution of neutral H and He in the solar system permit estimation of the contribution of interplanetary SWCX emission over the the whole sky and correction of the RASS maps. We find that the average SWCX contribution in the whole sky is 26 % +/- 6 % +/- 13 % for R1, 30 % +/- 4 % +/- 4 % for R2, 8 % +/- 5 % +/- 5 % for R4, 6 % +/- 4 % +/- 4 % for R5, and negligible for R6 and R7.

  13. Intermediate ionization continua for double charge exchange at high impact energies

    NASA Astrophysics Data System (ADS)

    Belkić, D.ževad

    1993-05-01

    We investigate the problem of two-electron capture from heliumlike atomic systems by bare nuclei ZP+(ZTe1,e2)i-->(ZPe1,e2)f+ZT at high incident energies, using the four-body formalism of the first- and second-order theories. Our goal is to establish the relative importance of the intermediate ionization continua of the two electrons in comparison with the usual direct path of the double electron transfer. For this purpose we presently introduce the boundary-corrected continuum-intermediate-state (BCIS) approximation, which preserves all the features of two-electron capture as a genuine four-body problem. The proposed second-order theory provides a fully adequate description of the fact that, in an intermediate stage of collision, both electrons move in the field of the two Coulomb centers. The previously devised boundary-corrected first Born (CB1) approximation can be obtained as a further simplification of the BCIS model if the invoked two-electron Coulomb waves are replaced by their long-range logarithmic phase factors defined in terms of the corresponding interaggregate separation R. The BCIS method is implemented on the symmetric resonant double charge exchange in collisions between α particles and He(1s2) at impact energies E>=900 keV. The obtained results for the differential and total cross sections are compared with the available experimental data and satisfactory agreement is recorded. As the incident energy increases, a dramatic improvement is obtained in going from the CB1 to the BCIS approximation, since the latter closely follows the measurement, whereas the former overestimates the observed total cross sections by two orders of magnitude.

  14. Semiautomated pH gradient ion-exchange chromatography of monoclonal antibody charge variants.

    PubMed

    Talebi, Mohammad; Shellie, Robert A; Hilder, Emily F; Lacher, Nathan A; Haddad, Paul R

    2014-10-01

    A new approach using a chromatography system equipped with isocratic pumps and an electrolytic eluent generator (EG) is introduced, replacing external pH gradient delivery using conventional gradient systems, in which bottled buffers with preadjusted pH are mixed using a gradient pump. The EG is capable of generating high purity base or acid required for online preparation of the buffer at the point of use, utilizing deionized water as the only carrier stream. Typically, the buffer was generated from online titration of a reagent composed of low molecular weight amines. The reagent was delivered isocratically into a static mixing tee, where it was titrated to the required pH with electrolytically generated base or acid. The required pH gradient was thus conveniently generated by electrically controlling the concentration of titrant. Also, since the pH was adjusted at the point of use, this approach offered enhanced throughput in terms of eluent preparation time and labor, and with a more reproducible pH profile. The performance of the system was demonstrated by running pH gradients ranging from pH 8.2 to 10.9 on a polymer monolith cation-exchange column for high throughput profiling of charge heterogeneity of intact, basic therapeutic monoclonal antibodies. A high degree of flexibility in modulating the key parameters of the pH gradient, including the buffer concentration, the pH gradient slope and the operating pH range was demonstrated. This enabled fine-tuning of the separation conditions for each individual antibody in order to enhance the chromatographic resolution. PMID:25199803

  15. Spectral modeling of the charge-exchange X-ray emission from M82

    SciTech Connect

    Zhang, Shuinai; Ji, Li; Zhou, Xin; Wang, Q. Daniel; Smith, Randall K.; Foster, Adam R.

    2014-10-10

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the Kα triplets of various He-like ions but also good fractions of the Lyα transitions of C VI (∼87%), O VIII, and N VII (≳50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 Å band originates in the CX. We infer an ion incident rate of 3 × 10{sup 51} s{sup –1} undergoing CX at the hot and cool gas interface and an effective area of the interface of ∼2 × 10{sup 45} cm{sup 2} that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  16. Upper-limit charge exchange cross sections for mercury (plus) on molybdenum and cesium (plus) on aluminum

    NASA Technical Reports Server (NTRS)

    Dugan, J. V., Jr.

    1972-01-01

    Upper-limit charge exchange cross sections are calculated for Hg(+) on Mo and Cs(+) on Al. The cross sections are calculated from the polarization interaction at low ion energies (1 to 500 eV) and by assuming favorable curve crossings with a hard-core reaction radius at higher energies (500 eV to 10 keV). The cross sections for Hg(+) on Mo becomes greater than corresponding Hg Hg(+) resonance values at ion energies below 2 eV, whereas the Cs(+) Al values remain considerably lower than the Cs(+)Cs resonance value at all ion energies. It is also shown that charge exchange of slow Hg(+) with Mo may be important for spacecraft with electron bombardment thrusters.

  17. Method to obtain absolute impurity density profiles combining charge exchange and beam emission spectroscopy without absolute intensity calibrationa)

    NASA Astrophysics Data System (ADS)

    Kappatou, A.; Jaspers, R. J. E.; Delabie, E.; Marchuk, O.; Biel, W.; Jakobs, M. A.

    2012-10-01

    Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.

  18. The TFTR E Parallel B Spectrometer for Mass and Energy Resolved Multi-Ion Charge Exchange Diagnostics

    SciTech Connect

    A.L. Roquemore; S.S. Medley

    1998-01-01

    The Charge Exchange Neutral Analyzer diagnostic for the Tokamak Fusion Test Reactor was designed to measure the energy distributions of both the thermal ions and the supra thermal populations arising from neutral-beam injection and ion cyclotron radio-frequency heating. These measurements yield the plasma ion temperature, as well as several other plasma parameters necessary to provide an understanding of the plasma condition and the performance of the auxiliary heating methods. For this application, a novel charge-exchange spectrometer using a dee-shaped region of parallel electric and magnetic fields was developed at the Princeton Plasma Physics Laboratory. The design and performance of this spectrometer is described in detail, including the effects of exposure of the microchannel plate detector to magnetic fields, neutrons, and tritium.

  19. Charge-exchange coupling between pickup ions across the heliopause and its effect on energetic neutral hydrogen flux

    SciTech Connect

    Zirnstein, E. J.; Heerikhuisen, J.; Zank, G. P.; Pogorelov, N. V.; McComas, D. J.; Desai, M. I.

    2014-03-10

    Pickup ions (PUIs) appear to play an integral role in the multi-component nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Three-dimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SW-LISM interaction with kinetic neutrals. First, we improve upon the multi-component treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through charge-exchange. We find a significant amount of energy is transferred away from hot, termination shock-processed PUIs into a colder, 'freshly injected' PUI population. Second, we extend the multi-component approach to estimate ENA flux from the outer heliosheath (OHS), formed from charge-exchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced charge-exchange. Our estimates, based on plasma-neutral simulations of the SW-LISM interaction and a post-processing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ∼0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through charge-exchange.

  20. Charge-exchange Coupling between Pickup Ions across the Heliopause and its Effect on Energetic Neutral Hydrogen Flux

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; Heerikhuisen, J.; Zank, G. P.; Pogorelov, N. V.; McComas, D. J.; Desai, M. I.

    2014-03-01

    Pickup ions (PUIs) appear to play an integral role in the multi-component nature of the plasma in the interaction between the solar wind (SW) and local interstellar medium (LISM). Three-dimensional (3D) MHD simulations with a kinetic treatment for neutrals and PUIs are currently still not viable. In light of recent energetic neutral atom (ENA) observations by the Interstellar Boundary EXplorer, the purpose of this paper is to illustrate the complex coupling between PUIs across the heliopause (HP) as facilitated by ENAs using estimates of PUI properties extracted from a 3D MHD simulation of the SW-LISM interaction with kinetic neutrals. First, we improve upon the multi-component treatment of the inner heliosheath (IHS) plasma from Zank et al. by including the extinction of PUIs through charge-exchange. We find a significant amount of energy is transferred away from hot, termination shock-processed PUIs into a colder, "freshly injected" PUI population. Second, we extend the multi-component approach to estimate ENA flux from the outer heliosheath (OHS), formed from charge-exchange between interstellar hydrogen atoms and energetic PUIs. These PUIs are formed from ENAs in the IHS that crossed the HP and experienced charge-exchange. Our estimates, based on plasma-neutral simulations of the SW-LISM interaction and a post-processing analysis of ENAs and PUIs, suggest the majority of flux visible at 1 AU from the front of the heliosphere, between ~0.02 and 10 keV, originates from OHS PUIs, indicating strong coupling between the IHS and OHS plasmas through charge-exchange.

  1. Exchange Flow Characteristics in a Tokamak Vacuum Vessel of Fusion Reactor Under the Loss-of-Vacuum Conditions

    NASA Astrophysics Data System (ADS)

    Takase, Kazuyuki; Kunugi, Tomoaki; Seki, Yasushi

    1997-06-01

    When a Tokamak vacuum vessel of fusion reactor is broken, buoyancy-driven exchange flows will take place through breaches after the inside pressure of the vacuum vessel (VV) becomes equal to the outside pressure. The exchange flow may bring a mixture of activated dusts and tritium from the inside of the VV to the outside through the breaches. Moreover, the exchange flow may remove decay heat from the plasma-facing components. A preliminary LOVA (Loss Of VAcuum event) apparatus was constructed to investigate quantitative heat transfer characteristics of the exchange flows through the breaches under the LOVA conditions. The results of this study, the relationship between Froude numbers and breach locations in the VV was determined and empirical correlations for the average Froude numbers were derived.

  2. Charge-Exchange Excitation of the Isobaric Analog State and Implication for the Nuclear Symmetry Energy and Neutron Skin

    NASA Astrophysics Data System (ADS)

    Khoa, Dao T.; Loc, Bui Minh; Zegers, R. G. T.

    The charge-exchange (p, n) or (3He,t) reaction can be considered as elastic scattering of proton or 3He by the isovector term of the optical potential that flips the projectile isospin. Therefore, the accurately measured charge-exchange scattering cross section for the isobaric analog states can be a good probe of the isospin dependence of the optical potential, which is determined exclusively within the folding model by the difference between the neutron and proton densities and isospin dependence of the nucleon-nucleon interaction. On the other hand, the same isospin- and density-dependent nucleon-nucleon interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part. As a result, the fine-tuning of the isospin dependence of the effective nucleon-nucleon interaction against the measured (p, n) or (3He,t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. Moreover, given the neutron skin of the target related directly to the neutron-proton difference of the ground-state density, it can be well probed in the analysis of the charge-exchange (3He,t) reactions at medium energies when the two-step processes can be neglected and the t-matrix interaction can be used in the folding calculation.

  3. Charge exchange of metastable 2D oxygen ions with molecular oxygen - A new source of thermospheric O2/+/ ions

    NASA Technical Reports Server (NTRS)

    Torr, D. G.; Torr, M. R.; Rusch, D. W.; Nier, A. O.; Kayser, D.; Hanson, W. B.; Hoffman, J. H.; Donahue, K.

    1979-01-01

    Reactions involving metastable ions are difficult to study in the laboratory. Much new information on these reactions has been derived from satellite measurements of aeronomic parameters. In this paper, Atmosphere Explorer D data are used to study charge exchange of metastable O(+)(2D) ions with O2. Using direct measurements of the O2 at 200 km to compute O2 densities at 300 km and supporting ionic concentrations and temperature observations, we find the rate coefficient for this reaction to be 1 + or - 0.6 times 10 to the minus 9th cu cm/sec. The process constitutes a significant source of O2(+) ions in the F2 layer at times when the N2 and O2 densities are enhanced. This finding leads to the conclusion that charge exchange with O2 must be a major sink for O(+)(2D) and an important source of O2(+) ions in the E region, because of the increase in the O2 concentration/N2 concentration ratio with decreasing altitude. The results imply that 80% of all O(+) ions formed in the E region are converted to O2(+) and that only about 20% of the metastable O(+) ions are converted into N2(+) through charge exchange with N2.

  4. Vertical distribution of overpotentials and irreversible charge losses in lithium ion battery electrodes.

    PubMed

    Klink, Stefan; Schuhmann, Wolfgang; La Mantia, Fabio

    2014-08-01

    Porous lithium ion battery electrodes are characterized using a vertical distribution of cross-currents. In an appropriate simplification, this distribution can be described by a transmission line model (TLM) consisting of infinitely thin electrode layers. To investigate the vertical distribution of currents, overpotentials, and irreversible charge losses in a porous graphite electrode in situ, a multi-layered working electrode (MWE) was developed as the experimental analogue of a TLM. In this MWE, each layer is in ionic contact but electrically insulated from the other layers by a porous separator. It was found that the negative graphite electrodes get lithiated and delithiated stage-by-stage and layer-by-layer. Several mass-transport- as well as non-mass-transport-limited processes could be identified. Local current densities can reach double the average, especially on the outermost layer at the beginning of each intercalation stage. Furthermore, graphite particles close to the counter electrode act as "electrochemical sieve" reducing the impurities present in the electrolyte such as water.

  5. Charge Changing Experiments and Multipole Expansions of Electron Loss to the Continuum.

    NASA Astrophysics Data System (ADS)

    Atan, H.

    Available from UMI in association with The British Library. Charge changing processes involving single electron loss for 0.6-2.2 MeV _sp{2}{4 }He^{+} ions and 2.0-3.0 MeV _sp{2}{3 }He^{+} ions, and single electron capture for 0.6-2.2 MeV _sp {2}{4}He^{+ } ions colliding with He, Ne and Ar have bee studied. The gas target was in the form of a gas beam jet, well localised and directed, obtained using a multicapillary array system. The measured absolute cross sections for single electron loss sigma_{12 }, were in good agreement with most other experimental data. These results were also compared with the theoretical quantal, semi-classical and classical calculations. For a He target, quantal Born approximation calculations gave good agreement especially towards the high energy region but not for an Ar target. The semi-classical calculations gave good agreement for all three target systems, in terms of the magnitude, velocity dependence as well the Z _{t}, dependence. The classical calculations gave not only a good estimate of the cross -sections but also predicted the velocity dependence quite accurately. The measured absolute cross sections for single electron capture sigma_{10} agreed well with most other experimental data and with the classical binary encounter calculations. Electron loss to the continuum (ELC) for 1.4-2.8 MeV He^{+} colliding with He, Ne and Ar have also been studied using a second-order focussing, 30^circ parallel plate spectrometer. The analysis was performed using a specially developed multipole expansion method, allowing an extraction of the parameters in an apparatus independent manner. The first order anisotropy parameter beta_1, was found to exhibit a systematic target dependence, with negative values for Ne and Ar targets, indicating an asymmetric cusp with an enhanced intensity of electrons at velocities lower than that of the ions. Such cusp shape was not predicted by any existing first-order theory. The second-order anisotropy parameter

  6. Charge exchange produced K-shell x-ray emission from Ar16+ in a tokamak plasma with neutral beam injection

    SciTech Connect

    Beiersdorfer, P; Bitter, M; Marion, M; Olson, R E

    2004-12-27

    High-resolution spectroscopy of hot tokamak plasma seeded with argon ions and interacting with an energetic, short-pulse neutral hydrogen beam was used to obtain the first high-resolution K-shell x-ray spectrum formed solely by charge exchange. The observed K-shell emission of Ar{sup 16+} is dominated by the intercombination and forbidden lines, providing clear signatures of charge exchange. Results from an ab initio atomic cascade model provide excellent agreement, validating a semiclassical approach for calculating charge exchange cross sections.

  7. Charge exchange dp → (pp)n reaction study at 1.75 A GeV/c by the STRELA spectrometer

    NASA Astrophysics Data System (ADS)

    Basilev, S. N.; Bushuev, Yu. P.; Glagolev, V. V.; Dolgiy, S. A.; Kirillov, D. A.; Kostyaeva, N. V.; Kovalenko, A. D.; Livanov, A. N.; Manyakov, P. K.; Martinská, G.; Mušinský, J.; Piskunov, N. M.; Povtoreiko, A. A.; Rukoyatkin, P. A.; Shindin, R. A.; Sitnik, I. M.; Slepnev, V. M.; Slepnev, I. V.; Urbán, J.

    2016-02-01

    The differential cross sections of the charge exchange reaction dp → (pp)n has been measured at 1.75 GeV/c momentum per nucleon for small transferred momenta using the one arm magnetic spectrometer STRELA at the Nuclotron accelerator. The ratio of the differential cross section of the charge exchange reaction dp → (pp)n to that of the np → pn elementary process is discussed in order to estimate the spin-dependent part of the np → pn charge exchange amplitude on the basis of dp → (pp)n data. The np → pn amplitude turned out to be predominantly spin-dependent.

  8. 26 CFR 1.1231-1 - Gains and losses from the sale or exchange of certain property used in the trade or business.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... for Determining Capital Gains and Losses § 1.1231-1 Gains and losses from the sale or exchange of... the involuntary conversion of capital assets held for more than 6 months shall be treated as long-term capital gains and losses if the total gains exceed the total losses. If the total gains do not exceed...

  9. EXCHANGE

    SciTech Connect

    Boltz, J.C.

    1992-09-01

    EXCHANGE is published monthly by the Idaho National Engineering Laboratory (INEL), a multidisciplinary facility operated for the US Department of Energy (DOE). The purpose of EXCHANGE is to inform computer users about about recent changes and innovations in both the mainframe and personal computer environments and how these changes can affect work being performed at DOE facilities.

  10. Removing Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charged Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, Brad

    2004-01-01

    Our research uses the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory to study X-ray emission from the charge exchange (CX) of highly charged ions with neutral gases. The resulting data help to fill a void in existing experimental and theoretical understanding of this atomic physics process, and are needed to explain all or part of the observed X-ray emission from the soft X-ray background, stellar winds, the Galactic Center and Galactic Ridge, supernova ejecta, and photoionized nebulae. Appreciation of the astrophysical relevance of our work continues to grow with the publication of roughly a dozen papers in the past four years describing Chandra and XMM observations of geocoronal and heliospheric CX emission, the temporal variation of such emission and correlation with X-ray emission enhancements observed by ROSAT, the theoretical spatial distribution of that emission, and CX emission around other stars. A similar number of papers were also published during that time describing CX emission from planets and comets. We expect that the launch of ASTRSE2, with its second-generation XRS microcalo- (with 6-eV resolution), will reveal even more clearly the contributions of CX to astrophysical emission. In our EBIT work we collected CX spectra from such ions as H-like and He-like Ne, Ar, and Fe. Our early measurements were made with a high-purity Ge detector, but during the second year we began operation of the first-generation XRS microcalorimeter (a twin of the XRS on ASTRO-E) and greatly improved the resolution of our measurements from roughly 150 eV (FWHM) with the Ge detectors to 10 eV with the XRS. We found that saturation of the XRS counting apparatus, which we described in our proposal as a potential concern, is not a problem for studying CX. During the course of our research, we expanded the number of injection gases permitted by the LLNL safety team, purchased and eventually operated an atomic H source, and clearly demonstrated the

  11. Charge exchange spectroscopy of multiply charged ions for the development of the EUV light source for the next generation photo lithography

    NASA Astrophysics Data System (ADS)

    Tanuma, Hajime

    2015-09-01

    As a candidate of an extreme ultra-violet (EUV) light source for a next generation lithography, laser produced plasmas (LPP) of Xe and Sn have been investigated intensively in this decade because these plasmas have a strong emission around 13.5 nm which had been determined as the wavelength for the EUV lithography. This emission was considered to be due to multiply charged Xe and Sn ions in hot plasmas. However, the detail atomic spectroscopic data of these multiply charged heavy ions had not been reported yet. To provide atomic data for the understanding and development of the LPP as the EUV light source, we have observed the EUV emission spectra from individual charge states of Xe and Sn ions by means of a charge exchange spectroscopy method. Multiply charged Xeq+ (q = 7-23) and Snq+ (q = 5-21) ions were produced with a 14.25 GHz electron cyclotron resonance ion source, and a charge-selected ion beam was directed into a collision chamber, where the ion interact with a target gas of He and Xe. EUV emissions from the collision center were observed with a compact flat-field grazing-incident spectrometer equipped with a liquid nitrogen cooled CCD camera. In experiments using Xe ions, we have found only Xe XI has a strong UTA (unresolved transition array) around 13.5 nm. On the other hand, various charge states of Sn from VIII to XIV contribute to the 13.5 nm emission. Identification of the transition lines was carried out by calculations using the Hebrew university Livermore laboratory atomic physics code and the Cowan code. Most of the emissions in the EUV region are attributed to the 4p-4d and 4d- nl (nl = 4f, 5p, and 5f) transitions. However, the 4d-4f transitions have approximately constant differences of about 0.5 nm between the experimental and theoretical results. This can be explained by considering the strong configuration interactions in the n=4 subshells. Using the experimental transition wavelengths of multiply charged Sn ions, theoretical modeling of

  12. A semi-interpenetrating network approach for dimensionally stabilizing highly-charged anion exchange membranes for alkaline fuel cells.

    PubMed

    He, Steve S; Strickler, Alaina L; Frank, Curtis W

    2015-04-24

    There is a delicate balance between ion exchange capacity (IEC), conductivity, and dimensional stability in anion exchange membranes as higher charge content can lead to increased water uptake, causing excessive swelling and charge dilution. Using highly-charged benzyltrimethylammonium polysulfone (IEC=2.99 mEq g(-1) ) as a benchmark (which ruptured in water even at room temperature), we report the ability to dramatically decrease water uptake using a semi-interpenetrating network wherein we reinforced the linear polyelectrolyte with a crosslinked poly(styrene-co-divinylbenzene) network. These membranes show enhanced dimensional stability as a result of lower water uptake (75 % vs. 301 % at 25 °C) while maintaining excellent hydroxide conductivity (up to 50 mS cm(-1) at 25 °C). These improvements produced an enhanced alkaline fuel cell capable of generating 236 mW cm(-2) peak power density at 80 °C. This method is easily adaptable and can be a viable strategy for stabilizing existing systems.

  13. Cometary Solar Wind Charge Exchange Line Ratios: Source of X-rays in Comet C/2000 WM1 (linear)

    NASA Astrophysics Data System (ADS)

    Mullen, Patrick Dean; Cumbee, Renata; Lyons, David; Gu, Liyi; Kaastra, Jelle S.; Shelton, Robin L.; Stancil, Phillip C.

    2016-06-01

    Cometary solar wind charge exchange (C-SWCX) occurs when highly charged projectile ions present in solar wind capture an electron from a target neutral species present in the cometary atmosphere. The availability of atomic and molecular data necessary for the X-ray emission modeling due to C-SWCX is limited; therefore, we apply multi-channel Landau-Zener (MCLZ) theory (Mullen et al. 2016) to generate cross section data and theoretical X-ray line ratios for a variety of bare and non-bare ion single electron capture (SEC) collisions. Namely, we consider collisions between the solar wind constituent H-like and He-like ions of C, N, O, Ne, Na, Al, and Si and the cometary neutrals H, H2O, CO, CO2, OH, and O. To exemplify the application of this data, we model the X-ray emission of comet C/2000 WM1 (linear) using the charge exchange package in SPEX (Gu et al. 2015) and find excellent agreement with observations made with the XMM-RGS detector. Our analyses show that the X-ray intensity is dominated by C-SWCX with H.Work at UGA was partially funded by NASA grant NNX13AF31G.References:Gu et al. 2016, A&A, accepted 22 January 2016Mullen et al. 2016, ApJS, in press

  14. An ion-exchange nanomembrane sensor for detection of nucleic acids using a surface charge inversion phenomenon.

    PubMed

    Senapati, Satyajyoti; Slouka, Zdenek; Shah, Sunny S; Behura, Susanta K; Shi, Zonggao; Stack, M Sharon; Severson, David W; Chang, Hsueh-Chia

    2014-10-15

    We present a novel low-cost biosensor for rapid, sensitive and selective detection of nucleic acids based on an ionic diode feature of an anion exchange nanoporous membrane under DC bias. The ionic diode feature is associated with external surface charge inversion on the positively charged anion exchange nanomembrane upon hybridization of negatively charged nucleic acid molecules to single-stranded oligoprobes functionalized on the membrane surface resulting in the formation of a cation selective monolayer. The resulting bipolar membrane causes a transition from electroconvection-controlled to water-splitting controlled ion conductance, with a large ion current signature that can be used to accurately quantify the hybridized nucleic acids. The platform is capable of distinguishing two base-pair mismatches in a 22-base pairing segment of microRNAs associated with oral cancer, as well as serotype-specific detection of dengue virus. We also show the sensor' capability to selectively capture target nucleic acids from a heterogeneous mixture. The limit of detection is 1 pM for short 27 base target molecules in a 15-min assay. Similar hybridization results are shown for short DNA molecules as well as RNAs from Brucella and Escherichia coli. The versatility and simplicity of this low-cost biosensor should enable point-of-care diagnostics in food, medical and environmental safety markets.

  15. A semi-interpenetrating network approach for dimensionally stabilizing highly-charged anion exchange membranes for alkaline fuel cells.

    PubMed

    He, Steve S; Strickler, Alaina L; Frank, Curtis W

    2015-04-24

    There is a delicate balance between ion exchange capacity (IEC), conductivity, and dimensional stability in anion exchange membranes as higher charge content can lead to increased water uptake, causing excessive swelling and charge dilution. Using highly-charged benzyltrimethylammonium polysulfone (IEC=2.99 mEq g(-1) ) as a benchmark (which ruptured in water even at room temperature), we report the ability to dramatically decrease water uptake using a semi-interpenetrating network wherein we reinforced the linear polyelectrolyte with a crosslinked poly(styrene-co-divinylbenzene) network. These membranes show enhanced dimensional stability as a result of lower water uptake (75 % vs. 301 % at 25 °C) while maintaining excellent hydroxide conductivity (up to 50 mS cm(-1) at 25 °C). These improvements produced an enhanced alkaline fuel cell capable of generating 236 mW cm(-2) peak power density at 80 °C. This method is easily adaptable and can be a viable strategy for stabilizing existing systems. PMID:25820199

  16. Design and operation of the pellet charge exchange diagnostic for measurement of energetic confined alphas and tritons on TFTR

    SciTech Connect

    Medley, S.S.; Duong, H.H.; Fisher, R.K.

    1996-05-01

    Radially-resolved energy and density distributions of the energetic confined alpha particles in D-T experiments on TFTR are being measured by active neutral particle analysis using low-Z impurity pellet injection. When injected into a high temperature plasma, an impurity pellet (e.g. Lithium or Boron) rapidly ablates forming an elongated cloud which is aligned with the magnetic field and moves with the pellet. This ablation cloud provides a dense target with which the alpha particles produced in D-T fusion reactions can charge exchange. A small fraction of the alpha particles incident on the pellet ablation cloud will be converted to helium neutrals whose energy is essentially unchanged by the charge transfer process. By measuring the resultant helium neutrals escaping from the plasma using a mass and energy resolving charge exchange analyzer, this technique offers a direct measurement of the energy distribution of the incident high-energy alpha particles. Other energetic ion species can be detected as well, such as tritons generated in D-D plasmas and H or He{sup 3} RF-driven minority ion tails. The diagnostic technique and its application on TFTR are described in detail.

  17. Energy loss rate of a charged particle in HgTe/(HgTe, CdTe) quantum wells

    SciTech Connect

    Chen, Qinjun; Sin Ang, Yee; Wang, Xiaolin; Lewis, R. A.; Zhang, Chao

    2013-11-04

    The energy loss rate (ELR) of a charged particle in a HgTe/(HgTe, CdTe) quantum well is investigated. We consider scattering of a charged particle by the bulk insulating states in this type of topological insulator. It is found that the ELR characteristics due to the intraband excitation have a linear energy dependence while those due to interband excitation depend on the energy exponentially. An interesting quantitative result is that for a large range of the incident energy, the mean inelastic scattering rate is around a few terahertz.

  18. Investigation of charge loss characteristics of HfO2 annealed in N2 or O2 ambient

    NASA Astrophysics Data System (ADS)

    Yuqiong, Chu; Zongliang, Huo; Yulong, Han; Guoxing, Chen; Dong, Zhang; Xinkai, Li; Ming, Liu

    2014-08-01

    The retention characteristics of electrons and holes in hafnium oxide with post-deposition annealing in a N2 or O2 ambient were investigated by Kelvin probe force microscopy. The KFM results show that compared with the N2 PDA process, the O2 PDA process can lead to a significant retention improvement. Vertical charge leakage and lateral charge spreading both played an important role in the charge loss mechanisms. The retention improvement is attributed to the deeper trap energy. For electrons, the trap energy of the HOS structure annealed in a N2 or O2 ambient were determined to be about 0.44 and 0.49 eV, respectively. For holes, these are about 0.34 and 0.36 eV, respectively. Finally, the electrical characteristics of the memory devices are demonstrated from the experiment, which agreed with our characterization results. The qualitative and quantitative determination of the charge retention properties, the possible charge decay mechanism and trap energy reported in this work can be very useful for the characterization of hafnium charge storage devices.

  19. Critical validity assessment of theoretical models: charge-exchange at intermediate and high energies

    NASA Astrophysics Data System (ADS)

    Belkić, Dževad

    1999-06-01

    Exact comprehensive computations are carried out by means of four leading second-order approximations yielding differential cross sections dQ/ dΩ for the basic charge exchange process H ++H(1s)→H(1s)+H + at intermediate and high energies. The obtained extensive set of results is thoroughly tested against all the existing experimental data with the purpose of critically assessing the validity of the boundary corrected second-Born (CB2), continuum-distorted wave (CDW), impulse approximation (IA) and the reformulated impulse approximation (RIA). The conclusion which emerges from this comparative study clearly indicates that the RIA agrees most favorably with the measurements available over a large energy range 25 keV-5 MeV. Such a finding reaffirms the few-particle quantum scattering theory which imposes several strict conditions on adequate second-order methods. These requirements satisfied by the RIA are: (i) normalisations of all the scattering wave functions, (ii) correct boundary conditions in both entrance and exit channels, (iii) introduction of a mathematically justified two-center continuum state for the sum of an attractive and a repulsive Coulomb potential with the same interaction strength, (iv) inclusion of the multiple scattering effects neglected in the IA, (v) a proper description of the Thomas double scattering in good agreement with the experiments and without any unobserved peak splittings. Nevertheless, the performed comparative analysis of the above four approximations indicates that none of the methods is free from some basic shortcomings. Despite its success, the RIA remains essentially a high-energy model like the other three methods under study. More importantly, their perturbative character leaves virtually no room for further systematic improvements, since the neglected higher-order terms are prohibitively tedious for practical purposes and have never been computed exactly. To bridge this gap, we presently introduce the variational Pad

  20. Effects of undercharge and internal loss on the rate dependence of battery charge storage efficiency

    NASA Astrophysics Data System (ADS)

    Krieger, Elena M.; Arnold, Craig B.

    2012-07-01

    Battery charge efficiency across a range of input powers is an important performance parameter in variable charging systems. Here we use equivalent circuit theory to model the inherent trade-off between battery charging power and energy stored and compare our model to the existing Ragone model for discharge power and energy. An additional parameter is included to account for undercharge and underdischarge of the battery due to premature arrival at the battery's voltage limits. At a given power, energy efficiency is predicted to be higher for charging than discharging when only accounting for energy dissipated by internal resistance. We experimentally determine charge and discharge energy-power curves for lithium-ion batteries and find they exhibit a reduction in energy stored or withdrawn as power increases. We isolate the effects of undercharge and underdischarge from energy lost to internal resistance, and find the former outweighs the latter effect. Furthermore, the shallow shape of the voltage curve near the charge voltage cutoff results in a more limited range of charging powers than discharging powers. The model is expected to help inform operational parameters for battery charging for variable power sources.

  1. Magnetospheric Solar Wind Charge Exchange - A Comparison Between the GUMICS-4 MHD Model and XMM-Newton.

    NASA Astrophysics Data System (ADS)

    Walach, M. T.; Whittaker, I. C.; Sembay, S.; Carter, J. A.; Read, A. M.

    2015-12-01

    The Solar Wind Earth Exchange Project (SWEEP) seeks to improve our understanding of the interaction of the solar wind with the Earth. X-ray emission resulting from charge exchange between oxygen in the solar wind and magnetospheric neutral hydrogen is modelled for a series of observations from XMM-Newton, an X-ray astronomical observatory. We use OMNI solar wind conditions, heavy ion composition data from ACE, the Hodges neutral hydrogen model and combine these with the GUMICS-4 MHD model to predict the global levels of X-ray emission from solar wind charge exchange (in the 0.5-0.7 keV band). The emission is then integrated along a line of sight and compared to the measured XMM-Newton sky background emissivity rates to determine the accuracy of these model predictions. Our results show that the magnitude of the integrated X-ray emissivity for both the modelled and observed flux is similar in a large number of cases, while the correlation of emission changes in detail between cases. We show that the accuracy of the oxygen density and relative charge state abundances is vital. The positional accuracy of the magnetopause is important as it forms the outer edge of the masking of the plasmasphere, including the cusps in our global emissivity rates. The derived position of the magnetopause and various masks are discussed with examples given, highlighting their relative accuracy. We also show the potential of X-ray emission for remote sensing of the magnetosphere, when used in combination with a wide field X-ray imaging system.

  2. Investigation of Anion-Exchange and Immunoaffinity Particle-Loaded Membranes for the Isolation of Charged Organic Analytes from Water

    USGS Publications Warehouse

    Dombrowski, T.R.; Wilson, G.S.; Thurman, E.M.

    1998-01-01

    Anion-exchange and immunoaffinity particle loaded membranes (PLMs) were investigated as a mechanism for the isolation of charged organic analytes from water. Kinetic properties determined theoretically included dynamic capacity, pressure drop (??P), residence and diffusion times (Tr, Td), and total membrane porosity (???T). These properties were confirmed through experimental evaluation, and the PLM method showed significant improvement over conventional solid-phase extraction (SPE) and ion-exchange formats. Recoveries of more than 90% were observed for a variety of test compounds at flow rates up to 70 mL/min (equipment-limited maximum flow rate). A fast-flow immunoaffinity column was developed using antibodies (Abs) attached to the PLMs. Reproducible recoveries (88% ?? 4%) were observed at flow rates up to 70 mL/min for the antibody (Ab)-loaded PLMs. Findings indicate increased selectivity over anion-exchange PLMs and conventional SPE or ion-exchange methods and rapid Ab-antigen binding rates given the excellent mass-transfer characteristics of the PLMs.

  3. The atmosphere of comet 67P/Churyumov-Gerasimenko diagnosed by charge-exchanged solar wind alpha particles

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, C.; Kallio, E.; Alho, M.; Nilsson, H.; Stenberg Wieser, G.; Gunell, H.; Behar, E.; Pusa, J.; Gronoff, G.

    2016-03-01

    Context. The ESA/Rosetta mission has been orbiting comet 67P/Churyumov-Gerasimenko since August 2014, measuring its dayside plasma environment. The ion spectrometer onboard Rosetta has detected two ion populations, one energetic with a solar wind origin (H+, He2+, He+), the other at lower energies with a cometary origin (water group ions such as H2O+). He+ ions arise mainly from charge-exchange between solar wind alpha particles and cometary neutrals such as H2O. Aims: The He+ and He2+ ion fluxes measured by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA) give insight into the composition of the dayside neutral coma, into the importance of charge-exchange processes between the solar wind and cometary neutrals, and into the way these evolve when the comet draws closer to the Sun. Methods: We combine observations by the ion spectrometer RPC-ICA onboard Rosetta with calculations from an analytical model based on a collisionless neutral Haser atmosphere and nearly undisturbed solar wind conditions. Results: Equivalent neutral outgassing rates Q can be derived using the observed RPC-ICA He+/He2+ particle flux ratios as input into the analytical model in inverse mode. A revised dependence of Q on heliocentric distance Rh in AU is found to be Rh-7.06 between 1.8 and 3.3 AU, suggesting that the activity in 2015 differed from that of the 2008 perihelion passage. Conversely, using an outgassing rate determined from optical remote sensing measurements from Earth, the forward analytical model results are in relatively good agreement with the measured RPC-ICA flux ratios. Modelled ratios in a 2D spherically-symmetric plane are also presented, showing that charge exchange is most efficient with solar wind protons. Detailed cometocentric profiles of these ratios are also presented. Conclusions: In conclusion, we show that, with the help of a simple analytical model of charge-exchange processes, a mass-capable ion spectrometer such as RPC-ICA can be used as a

  4. NUMEN Project @ LNS : Heavy ions double charge exchange reactions towards the 0νββ nuclear matrix element determination

    SciTech Connect

    Agodi, C. Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Cuttone, G.; Finocchiaro, P.; Pandola, L.; Rifuggiato, D.; Tudisco, S.; Cappuzzello, F.; Greco, V.; Bonanno, D. L.; Bongiovanni, D. G.; Longhitano, F.; Branchina, V.; Foti, A.; Lo Presti, D.; Lanzalone, G.; and others

    2015-10-28

    In the NUMEN Project it is proposed an innovative technique to access the nuclear matrix elements entering in the expression of the life-time of the neutrinoless double beta decay, using relevant cross sections of double charge exchange reactions. A key aspect is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN Laboratori Nazionali del Sud (LNS) K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  5. Charge-state-dependent collisional energy-loss straggling of swift ions in a degenerate electron gas

    NASA Astrophysics Data System (ADS)

    Nagy, I.; Aldazabal, I.

    2009-12-01

    In order to characterize the statistical aspect of the energy loss in particle penetration, Bohr developed a kinetic theory and applied it to a beam of fast α particles interacting with free electrons. The present study rests on this classical theory of collisional straggling, and it is implemented by using a partially screened Coulomb potential to model the electron-projectile interaction. The deflection angle of electron scattering in this long-ranged field is calculated analytically within the framework of classical mechanics. The transport fluctuation cross section, which is the basic quantity to the collisional straggling in Bohr’s modeling, is determined numerically. By varying the number of bound electrons around the swift He ions, the effect of prefixed charge states in the collisional energy-loss straggling is quantified. An incoherent weighted summation of different fixed charge-state channels is discussed as well, by using normalized probabilities.

  6. Effect of dense plasmas on exchange-energy shifts in highly charged ions: An alternative approach for arbitrary perturbation potentials

    SciTech Connect

    Rosmej, F.; Bennadji, K.; Lisitsa, V. S.

    2011-09-15

    An alternative method of calculation of dense plasma effects on exchange-energy shifts {Delta}E{sub x} of highly charged ions is proposed which results in closed expressions for any plasma or perturbation potential. The method is based on a perturbation theory expansion for the inner atomic potential produced by charged plasma particles employing the Coulomb Green function method. This approach allows us to obtain analytic expressions and scaling laws with respect to the electron temperature T, density n{sub e}, and nuclear charge Z. To demonstrate the power of the present method, two specific models were considered in detail: the ion sphere model (ISM) and the Debye screening model (DSM). We demonstrate that analytical expressions can be obtained even for the finite temperature ISM. Calculations have been carried out for the singlet 1s2p{sup 1} P{sub 1} and triplet 1s2p{sup 3} P{sub 1} configurations of He-like ions with charge Z that can be observed in dense plasmas via the He-like resonance and intercombination lines. Finally we discuss recently available purely numerical calculations and experimental data.

  7. Membrane surface charge dictates the structure and function of the epithelial Na+/H+ exchanger

    PubMed Central

    Alexander, Robert Todd; Jaumouillé, Valentin; Yeung, Tony; Furuya, Wendy; Peltekova, Iskra; Boucher, Annie; Zasloff, Michael; Orlowski, John; Grinstein, Sergio

    2011-01-01

    The Na+/H+ exchanger NHE3 plays a central role in intravascular volume and acid–base homeostasis. Ion exchange activity is conferred by its transmembrane domain, while regulation of the rate of transport by a variety of stimuli is dependent on its cytosolic C-terminal region. Liposome- and cell-based assays employing synthetic or recombinant segments of the cytosolic tail demonstrated preferential association with anionic membranes, which was abrogated by perturbations that interfere with electrostatic interactions. Resonance energy transfer measurements indicated that segments of the C-terminal domain approach the bilayer. In intact cells, neutralization of basic residues in the cytosolic tail by mutagenesis or disruption of electrostatic interactions inhibited Na+/H+ exchange activity. An electrostatic switch model is proposed to account for multiple aspects of the regulation of NHE3 activity. PMID:21245831

  8. Use of the TFTR prototype charge exchange neutral analyzer for fast He/sub 3//sup + +/ diagnostics during ICRF heating on PLT

    SciTech Connect

    Medley, S.S.

    1981-07-01

    The Charge Exchange Neutral Analyzer (CENA) for TFTR is designed to measure singly charged ion species of atomic mass A = 1, 2, and 3 simultaneously with up to 75 energy channels per mass and an energy range of 0.5 < AE < 600, where AE is in units of AMU.keV. Plans to test the prototype analyzer on PLT prior to installation on TFTR are discussed. The capability of the analyzer to simultaneously measure singly reionized H, D, and He/sub 3/ charge exchange neutrals makes the analyzer of particular interest for recently proposed fast He/sub 3//sup + +/ diagnostics during ICRF heating on PLT.

  9. Charge transfer and momentum exchange in exospheric D-H(+) and H-D(+) collisions

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.; Breig, E. L.

    1993-01-01

    Mechanisms that control the escape of deuterium from planetary exospheres include the acceleration of D(+) in the polar wind, and the production of suprathermal D atoms through nonthermal collisions. In this paper we examine the effects of neutral-ion interactions involving deuterium and hydrogen on the velocity distribution of neutral D. A two-center scattering approximation is used as the basis for calculations of the differential cross sections for charge transfer and elastic scatter in collision of H with D(+) and of D with H(+) for ionosphere-exosphere collision energies below 10 e V. These data are used to derive temperature dependent rate coefficients for the charge transfer branches of these interactions, and to determine the effects of ion-neutral temperature differences on the rate of generation of suprathermal D through charge transfer and elastic scatter.

  10. Magnetic Field Generation through Angular Momentum Exchange between Circularly Polarized Radiation and Charged Particles

    SciTech Connect

    G. Shvets; N.J. Fisch; J.-M. Rax

    2002-01-18

    The interaction between circularly polarized (CP) radiation and charged particles can lead to generation of magnetic field through an inverse Faraday effect. The spin of the circularly polarized electromagnetic wave can be converted into the angular momentum of the charged particles so long as there is dissipation. We demonstrate this by considering two mechanisms of angular momentum absorption relevant for laser-plasma interactions: electron-ion collisions and ionization. The precise dissipative mechanism, however, plays a role in determining the efficiency of the magnetic field generation.

  11. Two-stage Rydberg charge exchange in a strong magnetic field

    SciTech Connect

    Wall, M. L.; Norton, C. S.; Robicheaux, F.

    2005-11-15

    We have performed calculations of two successive charge transfers from Rydberg states in a strong magnetic field. In the first charge transfer, a positron interacts with a highly excited atom to form positronium. In the second stage, the positronium interacts with an antiproton to give antihydrogen. For many parameters, our results are in qualitative agreement with previous calculations with no magnetic field. However, we do find that there are important changes which may affect the usefulness of the method for efficient formation of antihydrogen that can be trapped.

  12. STRUCTURE OF THE INTERSTELLAR BOUNDARY EXPLORER RIBBON FROM SECONDARY CHARGE-EXCHANGE AT THE SOLAR–INTERSTELLAR INTERFACE

    SciTech Connect

    Zirnstein, E. J.; McComas, D. J.; Heerikhuisen, J. E-mail: dmccomas@swri.edu

    2015-05-01

    In 2009, the Interstellar Boundary Explorer discovered a bright “ribbon” of energetic neutral atom (ENA) flux in the energy range ≤0.4–6 keV, encircling a large portion of the sky. This observation was not previously predicted by any models or theories, and since its discovery, it has been the subject of numerous studies of its origin and properties. One of the most studied mechanisms for its creation is the “secondary ENA” process. Here, solar wind ions, neutralized by charge-exchange with interstellar atoms, propagate outside the heliopause; experience two charge-exchange events in the dense outer heliosheath; and then propagate back inside the heliosphere, preferentially in the direction perpendicular to the local interstellar magnetic field. This process has been extensively analyzed using state-of-the-art modeling and simulation techniques, but it has been difficult to visualize. In this Letter, we show the three-dimensional structure of the source of the ribbon, providing a physical picture of the spatial and energy scales over which the secondary ENA process occurs. These results help us understand how the ribbon is generated and further supports a secondary ENA process as the leading ribbon source mechanism.

  13. Structure of the Interstellar Boundary Explorer Ribbon from Secondary Charge-exchange at the Solar-Interstellar Interface

    NASA Astrophysics Data System (ADS)

    Zirnstein, E. J.; Heerikhuisen, J.; McComas, D. J.

    2015-05-01

    In 2009, the Interstellar Boundary Explorer discovered a bright “ribbon” of energetic neutral atom (ENA) flux in the energy range ≤0.4-6 keV, encircling a large portion of the sky. This observation was not previously predicted by any models or theories, and since its discovery, it has been the subject of numerous studies of its origin and properties. One of the most studied mechanisms for its creation is the “secondary ENA” process. Here, solar wind ions, neutralized by charge-exchange with interstellar atoms, propagate outside the heliopause; experience two charge-exchange events in the dense outer heliosheath; and then propagate back inside the heliosphere, preferentially in the direction perpendicular to the local interstellar magnetic field. This process has been extensively analyzed using state-of-the-art modeling and simulation techniques, but it has been difficult to visualize. In this Letter, we show the three-dimensional structure of the source of the ribbon, providing a physical picture of the spatial and energy scales over which the secondary ENA process occurs. These results help us understand how the ribbon is generated and further supports a secondary ENA process as the leading ribbon source mechanism.

  14. Operation of the TFTR Pellet Charge Exchange Diagnostic in the Pulse Counting Mode during H+ RF-minority Heating

    SciTech Connect

    Medley, S.S., PPPL

    1998-05-01

    The Pellet Charge Exchange technique on TFTR has been used primarily to obtain active charge exchange measurements using a high energy (0.5 - 4.0 MeV) neutral particle analyzer (NPA) in conjunction with impurity pellet injection (Li and B) with the scintillator-photomultiplier detector system operated in the current mode. While passive measurements using pulse counting were also obtained using this instrumentation, operation in this mode was very restrictive with pulse counting rates limited to less than {approximately}10 kHz in the absence of any significant neutron and gamma induced background signal. An upgrade to a specialized pulse counting capability which was developed by the Ioffe Institute was implemented which consisted of CsI(Tl) scintillators having features designed to minimize signals induced by background neutron and gamma rays and 16-channel pulse height analysis electronics on each of the eight NPA energy channels. Passive measurements of RF-driven energetic hydrogen minority ions which served to verify operation of the pulse counting mode are reported. It is shown that in the passive mode the main donors for the neutralization of H+ ions in this energy range are C5+ ions. The measured effective H+ tail temperatures range from 0.15 MeV at an RF power of 2 MW to 0.35 MeV at 6 MW.

  15. The effect of the charge exchange source on the velocity and 'temperature' distributions and their anisotropies in the earth's exosphere

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.; Rohrbaugh, R. P.; Tinsley, B. A.

    1981-01-01

    The velocity distribution of atomic hydrogen in the earth's exosphere is calculated as a function of altitude and direction taking into account both the classic exobase source and the higher-altitude plasmaspheric charge exchange source. Calculations are performed on the basis of a Monte Carlo technique in which random ballistic trajectories of individual atoms are traced through a three-dimensional grid of audit zones, at which relative concentrations and momentum or energy fluxes are obtained. In the case of the classical exobase source alone, the slope of the velocity distribution is constant only for the upward radial velocity component and increases dramatically with altitude for the incoming radial and transverse velocity components, resulting in a temperature decrease. The charge exchange source, which produces the satellite hydrogen component and the hot ballistic and escape components of the exosphere, is found to enhance the wings of the velocity distributions, however this effect is not sufficient to overcome the temperature decreases at altitudes above one earth radius. The resulting global model of the hydrogen exosphere may be used as a realistic basis for radiative transfer calculations.

  16. The effect of the charge exchange source on the velocity and 'temperature' distributions and their anisotropies in the earth's exosphere

    NASA Astrophysics Data System (ADS)

    Hodges, R. R., Jr.; Rohrbaugh, R. P.; Tinsley, B. A.

    1981-08-01

    The velocity distribution of atomic hydrogen in the earth's exosphere is calculated as a function of altitude and direction taking into account both the classic exobase source and the higher-altitude plasmaspheric charge exchange source. Calculations are performed on the basis of a Monte Carlo technique in which random ballistic trajectories of individual atoms are traced through a three-dimensional grid of audit zones, at which relative concentrations and momentum or energy fluxes are obtained. In the case of the classical exobase source alone, the slope of the velocity distribution is constant only for the upward radial velocity component and increases dramatically with altitude for the incoming radial and transverse velocity components, resulting in a temperature decrease. The charge exchange source, which produces the satellite hydrogen component and the hot ballistic and escape components of the exosphere, is found to enhance the wings of the velocity distributions, however this effect is not sufficient to overcome the temperature decreases at altitudes above one earth radius. The resulting global model of the hydrogen exosphere may be used as a realistic basis for radiative transfer calculations.

  17. Optimal battery charging, Part I: Minimizing time-to-charge, energy loss, and temperature rise for OCV-resistance battery model

    NASA Astrophysics Data System (ADS)

    Abdollahi, A.; Han, X.; Avvari, G. V.; Raghunathan, N.; Balasingam, B.; Pattipati, K. R.; Bar-Shalom, Y.

    2016-01-01

    In this paper we present a closed-form solution to the problem of optimally charging a Li-ion battery. A combination of three cost functions is considered as the objective function: time-to-charge (TTC), energy losses (EL), and a temperature rise index (TRI). First, we consider the cost function of the optimization problem as a weighted sum of TTC and EL. We show that the optimal charging strategy in this case is the well-known Constant Current-Constant Voltage (CC-CV) policy with the value of the current in the CC stage being a function of the ratio of weighting on TTC and EL and of the resistance of the battery. Then, we extend the cost function to a weighted sum of TTC, EL and TRI and derive an analytical solution for the problem. It is shown that the analytical solution can be approximated by a CC-CV with the value of current in the CC stage being a function of ratio of weighting on TTC and EL, resistance of the battery and the effective thermal resistance.

  18. Calculation of total cross sections for charge exchange in molecular collisions

    NASA Technical Reports Server (NTRS)

    Ioup, J.

    1979-01-01

    Areas of investigation summarized include nitrogen ion-nitrogen molecule collisions; molecular collisions with surfaces; molecular identification from analysis of cracking patterns of selected gases; computer modelling of a quadrupole mass spectrometer; study of space charge in a quadrupole; transmission of the 127 deg cylindrical electrostatic analyzer; and mass spectrometer data deconvolution.

  19. Ion-exchange molecularly imprinted polymer for the extraction of negatively charged acesulfame from wastewater samples.

    PubMed

    Zarejousheghani, Mashaalah; Schrader, Steffi; Möder, Monika; Lorenz, Pierre; Borsdorf, Helko

    2015-09-11

    Acesulfame is a known indicator that is used to identify the introduction of domestic wastewater into water systems. It is negatively charged and highly water-soluble at environmental pH values. In this study, a molecularly imprinted polymer (MIP) was synthesized for negatively charged acesulfame and successfully applied for the selective solid phase extraction (SPE) of acesulfame from influent and effluent wastewater samples. (Vinylbenzyl)trimethylammonium chloride (VBTA) was used as a novel phase transfer reagent, which enhanced the solubility of negatively charged acesulfame in the organic solvent (porogen) and served as a functional monomer in MIP synthesis. Different molecularly imprinted polymers were synthesized to optimize the extraction capability of acesulfame. The different materials were evaluated using equilibrium rebinding experiments, selectivity experiments and scanning electron microscopy (SEM). The most efficient MIP was used in a molecularly imprinted-solid phase extraction (MISPE) protocol to extract acesulfame from wastewater samples. Using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) analysis, detection and quantification limits were achieved at 0.12μgL(-1) and 0.35μgL(-1), respectively. Certain cross selectivity for the chemical compounds containing negatively charged sulfonamide functional group was observed during selectivity experiments. PMID:26256920

  20. Ion-exchange molecularly imprinted polymer for the extraction of negatively charged acesulfame from wastewater samples.

    PubMed

    Zarejousheghani, Mashaalah; Schrader, Steffi; Möder, Monika; Lorenz, Pierre; Borsdorf, Helko

    2015-09-11

    Acesulfame is a known indicator that is used to identify the introduction of domestic wastewater into water systems. It is negatively charged and highly water-soluble at environmental pH values. In this study, a molecularly imprinted polymer (MIP) was synthesized for negatively charged acesulfame and successfully applied for the selective solid phase extraction (SPE) of acesulfame from influent and effluent wastewater samples. (Vinylbenzyl)trimethylammonium chloride (VBTA) was used as a novel phase transfer reagent, which enhanced the solubility of negatively charged acesulfame in the organic solvent (porogen) and served as a functional monomer in MIP synthesis. Different molecularly imprinted polymers were synthesized to optimize the extraction capability of acesulfame. The different materials were evaluated using equilibrium rebinding experiments, selectivity experiments and scanning electron microscopy (SEM). The most efficient MIP was used in a molecularly imprinted-solid phase extraction (MISPE) protocol to extract acesulfame from wastewater samples. Using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) analysis, detection and quantification limits were achieved at 0.12μgL(-1) and 0.35μgL(-1), respectively. Certain cross selectivity for the chemical compounds containing negatively charged sulfonamide functional group was observed during selectivity experiments.

  1. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    DOE PAGES

    Feygenson, Mikhail; Bauer, John C; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S; Kevin, Beyer; et al

    2015-08-10

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron scattering, synchrotron x-ray diffraction and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wüstite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatchmore » between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed across the interface to accommodate an excess of oxygen released during the reduction of magnetite.« less

  2. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    SciTech Connect

    Feygenson, Mikhail; Bauer, John C.; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S.; Beyer, Kevin A.; Dai, Sheng

    2015-08-10

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron-scattering, synchrotron x-ray diffraction, and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wustite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatch between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into the FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed, presumably across the interface to accommodate an excess of oxygen released during the reduction of magnetite

  3. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 2. Assessing Charge Site Location and Isotope Scrambling

    NASA Astrophysics Data System (ADS)

    Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Donohoe, Gregory C.; Valentine, Stephen J.

    2016-03-01

    Ion mobility spectrometry (IMS) coupled with gas-phase hydrogen deuterium exchange (HDX)-mass spectrometry (MS) and molecular dynamic simulations (MDS) has been used for structural investigation of anions produced by electrospraying a sample containing a synthetic peptide having the sequence KKDDDDDIIKIIK. In these experiments the potential of the analytical method for locating charge sites on ions as well as for utilizing collision-induced dissociation (CID) to reveal the degree of deuterium uptake within specific amino acid residues has been assessed. For diffuse (i.e., more elongated) [M - 2H]2- ions, decreased deuterium content along with MDS data suggest that the D4 and D6 residues are charge sites, whereas for the more diffuse [M - 3H]3- ions, the data suggest that the D4, D7, and the C-terminus are deprotonated. Fragmentation of mobility-selected, diffuse [M - 2H]2- ions to determine deuterium uptake at individual amino acid residues reveals a degree of deuterium retention at incorporation sites. Although the diffuse [M - 3H]3- ions may show more HD scrambling, it is not possible to clearly distinguish HD scrambling from the expected deuterium uptake based on a hydrogen accessibility model. The capability of the IMS-HDX-MS/MS approach to provide relevant details about ion structure is discussed. Additionally, the ability to extend the approach for locating protonation sites on positively-charged ions is presented.

  4. The velocity dependence of X-ray emission due to Charge Exchange: Applications in the Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Cumbee, Renata; Lyons, David; Mullen, Patrick; Shelton, Robin L.; Stancil, Phillip C.; Schultz, David R.

    2016-04-01

    The fundamental collisional process of charge exchange (CX) has been been established as a primary source of X-ray emission from the heliosphere [1], planetary exospheres [2], and supernova remnants [3,4]. In this process, X-ray emission results from the capture of an electron by a highly charged ion from a neutral atom or molecule, to form a highly-excited, high charge state ion. As the captured electron cascades down to the lowest energy level, photons are emitted, including X-rays.To provide reliable CX-induced X-ray spectral models to realistically simulate high-energy astrophysical environments, line ratios and spectra are computed using theoretical CX cross-sections obtained with the multi-channel Landau-Zener, atomic-orbital close-coupling, and classical-trajectory Monte Carlo methods for various collisional velocities. Collisions of bare and H-like C to Al ions with H, He, and H2 are considered. Using these line ratios, XSPEC models of CX emission in the northeast rim of the Cygnus Loop supernova remnant will be shown as an example with ion velocity dependence.[1] Henley, D. B. & Shelton, R. L. 2010, ApJSS, 187, 388[2] Dennerl, K. et al. 2002, A&A 386, 319[3] Katsuda, S. et al. 2011, ApJ 730 24[4] Cumbee, R. S. et al. 2014, ApJ 787 L31

  5. 26 CFR 1.988-2 - Recognition and computation of exchange gain or loss.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... U.S. dollar basis 1/01/89 1000 Sf $500 $500 3/31/89 50 Sf 25 525 6/30/89 50 Sf 24 549 9/30/89 50 Sf 25 574 12/31/89 50 Sf 26 600 (ii) On January 1, 1990, X withdraws 500 Swiss francs from the account... 26 Internal Revenue 10 2013-04-01 2013-04-01 false Recognition and computation of exchange gain...

  6. Sustained Weight Loss with Vagal Nerve Blockade but Not with Sham: 18-Month Results of the ReCharge Trial

    PubMed Central

    Shikora, Scott A.; Wolfe, Bruce M.; Apovian, Caroline M.; Anvari, Mehran; Sarwer, David B.; Gibbons, Robert D.; Ikramuddin, Sayeed; Miller, Christopher J.; Knudson, Mark B.; Tweden, Katherine S.; Sarr, Michael G.; Billington, Charles J.

    2015-01-01

    Background/Objectives. Vagal block therapy (vBloc) is effective for moderate to severe obesity at one year. Subjects/Methods. The ReCharge trial is a double-blind, randomized controlled clinical trial of 239 participants with body mass index (BMI) of 40 to 45 kg/m or 35 to 40 kg/m with one or more obesity-related conditions. Interventions were implantation of either vBloc or Sham devices and weight management counseling. Mixed models assessed percent excess weight loss (%EWL) and total weight loss (%TWL) in intent-to-treat analyses. At 18 months, 142 (88%) vBloc and 64 (83%) Sham patients remained enrolled in the study. Results. 18-month weight loss was 23% EWL (8.8% TWL) for vBloc and 10% EWL (3.8% TWL) for Sham (P < 0.0001). vBloc patients largely maintained 12-month weight loss of 26% EWL (9.7% TWL). Sham regained over 40% of the 17% EWL (6.4% TWL) by 18 months. Most weight regain preceded unblinding. Common adverse events of vBloc through 18 months were heartburn/dyspepsia and abdominal pain; 98% of events were reported as mild or moderate and 79% had resolved. Conclusions. Weight loss with vBloc was sustained through 18 months, while Sham regained weight between 12 and 18 months. vBloc is effective with a low rate of serious complications. PMID:26246907

  7. Proton exchange membrane fuel cell model for aging predictions: Simulated equivalent active surface area loss and comparisons with durability tests

    NASA Astrophysics Data System (ADS)

    Robin, C.; Gérard, M.; Quinaud, M.; d'Arbigny, J.; Bultel, Y.

    2016-09-01

    The prediction of Proton Exchange Membrane Fuel Cell (PEMFC) lifetime is one of the major challenges to optimize both material properties and dynamic control of the fuel cell system. In this study, by a multiscale modeling approach, a mechanistic catalyst dissolution model is coupled to a dynamic PEMFC cell model to predict the performance loss of the PEMFC. Results are compared to two 2000-h experimental aging tests. More precisely, an original approach is introduced to estimate the loss of an equivalent active surface area during an aging test. Indeed, when the computed Electrochemical Catalyst Surface Area profile is fitted on the experimental measures from Cyclic Voltammetry, the computed performance loss of the PEMFC is underestimated. To be able to predict the performance loss measured by polarization curves during the aging test, an equivalent active surface area is obtained by a model inversion. This methodology enables to successfully find back the experimental cell voltage decay during time. The model parameters are fitted from the polarization curves so that they include the global degradation. Moreover, the model captures the aging heterogeneities along the surface of the cell observed experimentally. Finally, a second 2000-h durability test in dynamic operating conditions validates the approach.

  8. Neutralizing positive charges at the surface of a protein lowers its rate of amide hydrogen exchange without altering its structure or increasing its thermostability.

    PubMed

    Shaw, Bryan F; Arthanari, Haribabu; Narovlyansky, Max; Durazo, Armando; Frueh, Dominique P; Pollastri, Michael P; Lee, Andrew; Bilgicer, Basar; Gygi, Steven P; Wagner, Gerhard; Whitesides, George M

    2010-12-15

    This paper combines two techniques--mass spectrometry and protein charge ladders--to examine the relationship between the surface charge and hydrophobicity of a representative globular protein (bovine carbonic anhydrase II; BCA II) and its rate of amide hydrogen-deuterium (H/D) exchange. Mass spectrometric analysis indicated that the sequential acetylation of surface lysine-ε-NH3(+) groups--a type of modification that increases the net negative charge and hydrophobicity of the surface of BCA II without affecting its secondary or tertiary structure--resulted in a linear decrease in the aggregate rate of amide H/D exchange at pD 7.4, 15 °C. According to analysis with MS, the acetylation of each additional lysine generated between 1.4 and 0.9 additional hydrogens that are protected from H/D exchange during the 2 h exchange experiment at 15 °C, pD 7.4. NMR spectroscopy demonstrated that none of the hydrogen atoms which became protected upon acetylation were located on the side chain of the acetylated lysine residues (i.e., lys-ε-NHCOCH3) but were instead located on amide NHCO moieties in the backbone. The decrease in rate of exchange associated with acetylation paralleled a decrease in thermostability: the most slowly exchanging rungs of the charge ladder were the least thermostable (as measured by differential scanning calorimetry). This observation--that faster rates of exchange are associated with slower rates of denaturation--is contrary to the usual assumptions in protein chemistry. The fact that the rates of H/D exchange were similar for perbutyrated BCA II (e.g., [lys-ε-NHCO(CH2)2CH3]18) and peracetylated BCA II (e.g., [lys-ε-NHCOCH3]18) suggests that the electrostatic charge is more important than the hydrophobicity of surface groups in determining the rate of H/D exchange. These electrostatic effects on the kinetics of H/D exchange could complicate (or aid) the interpretation of experiments in which H/D exchange methods are used to probe the structural

  9. Symmetric Resonance Charge Exchange Cross Section Based on Impact Parameter Treatment

    NASA Technical Reports Server (NTRS)

    Omidvar, Kazem; Murphy, Kendrah; Atlas, Robert (Technical Monitor)

    2002-01-01

    Using a two-state impact parameter approximation, a calculation has been carried out to obtain symmetric resonance charge transfer cross sections between nine ions and their parent atoms or molecules. Calculation is based on a two-dimensional numerical integration. The method is mostly suited for hydrogenic and some closed shell atoms. Good agreement has been obtained with the results of laboratory measurements for the ion-atom pairs H+-H, He+-He, and Ar+-Ar. Several approximations in a similar published calculation have been eliminated.

  10. A comparison of experimental and computer model results on the charge-exchange plasma flow from a 30 cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Gabriel, S. B.; Kaufman, H. R.

    1982-01-01

    Ion thrusters can be used in a variety of primary and auxiliary space-propulsion applications. A thruster produces a charge-exchange plasma which can interact with various systems on the spacecraft. The propagation of the charge-exchange plasma is crucial in determining the interaction of that plasma with the spacecraft. This paper compares experimental measurements with computer model predictions of the propagation of the charge-exchange plasma from a 30 cm mercury ion thruster. The plasma potentials, and ion densities, and directed energies are discussed. Good agreement is found in a region upstream of, and close to, the ion thruster optics. Outside of this region the agreement is reasonable in view of the modeling difficulties.

  11. The T{sub z} = -1{yields}T{sub z} =0 beta decays and comparison with Charge Exchange reactions

    SciTech Connect

    Molina, F.; Rubio, B.; Fujita, Y.; Gelletly, W.; Collaboration: Santiago Collaboration

    2011-11-30

    Gamow-Teller (GT) transitions can be studied in both {beta} decay and charge exchange (CE) reactions. If isospin is a good quantum number, then the Tz = -1{yields}0 and Tz = +1{yields}0GT mirror transitions, are identical. Therefore, a comparison of the results from studies of {beta} decay and CE should shed light on this assumption. Accordingly we have studied the {beta} decay of the Tz = -1 fp-shell nuclei, {sup 54}Ni, {sup 50}Fe, {sup 46}Cr, and {sup 42}Ti, produced in fragmentation and we have compared our results with the spectra from ({sup 3}He, t) measurements on the mirror Tz = +1 target nuclei studied in high resolution at RCNP, Osaka. The {beta} decay experiments were performed as part of the STOPPED beam RISING campaign at GSI.

  12. Optimization of a compact multicusp He{sup +} ion source for double-charge-exchanged He{sup -} beam

    SciTech Connect

    Shinto, K.; Sugawara, H.; Takenaga, M.; Takeuchi, S.; Tanaka, N.; Okamoto, A.; Kitajima, S.; Sasao, M.; Nishiura, M.; Wada, M.

    2006-03-15

    Preliminary test bench results to study the beam quality extracted from a compact multicusp He{sup +} ion source for He{sup -} beam production are reported. The bench is a part of the beam diagnostic system equipped with energy analyzers, emittance meters, focusing beam optics, an alkali-metal charge-exchange cell, a neutral particle energy analyzer, a double focusing magnetic momentum analyzer, a postaccelerator, and a drift tube. Utilizing the front end of the bench, the transverse emittance and the energy distribution function of a He{sup +} beam extracted from a multi-line-cusp magnetic-field ion source 8 cm in diameter and 9 cm in length were measured. The results indicated that improvements in both formation of the plasma meniscus and reinforcement of pumping in the extraction region are necessary to produce a higher brightness He{sup +} beam.

  13. Monte Carlo simulation of ion-neutral charge exchange collisions and grid erosion in an ion thruster

    NASA Technical Reports Server (NTRS)

    Peng, Xiaohang; Ruyten, Wilhelmus M.; Keefer, Dennis

    1991-01-01

    A combined particle-in-cell (PIC)/Monte Carlo simulation model has been developed in which the PIC method is used to simulate the charge exchange collisions. It is noted that a number of features were reproduced correctly by this code, but that its assumption of two-dimensional axisymmetry for a single set of grid apertures precluded the reproduction of the most characteristic feature of actual test data; namely, the concentrated grid erosion at the geometric center of the hexagonal aperture array. The first results of a three-dimensional code, which takes into account the hexagonal symmetry of the grid, are presented. It is shown that, with this code, the experimentally observed erosion patterns are reproduced correctly, demonstrating explicitly the concentration of sputtering between apertures.

  14. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    SciTech Connect

    Kaita, R.; Heidbrink, W.W.; Hammett, G.W.; Chan, A.A.; England, A.C.; Hendel, H.W.; Medley, S.S.; Nieschmidt, E.; Roquemore, A.L.; Scott, S.D.

    1986-04-01

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and /sup 3/He ions, respectively. When the plasma was compressed, the d(d,n)/sup 3/He fusion reaction rate increased a factor of five, and the /sup 3/He(d,p)/sup 4/He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling.

  15. What Can Be Learned from X-Ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes?

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.

    2008-01-01

    Both solar wind charge exchange emission and diffuse thermal emission from the Local Bubble are strongly dominated in the soft X-ray band by lines from highly ionized elements. While both processes share many of the same lines, the spectra should differ significantly due to the different production mechanisms, abundances, and ionization states. Despite their distinct spectral signatures, current and past observatories have lacked the spectral resolution to adequately distinguish between the two sources. High-resolution X-ray spectroscopy instrumentation proposed for future missions has the potential to answer fundamental questions such as whether there is any hot plasma in the Local Hot Bubble, and if so, what are the abundances of the emitting plasma and whether the plasma is in equilibrium. Such instrumentation will provide dynamic information about the solar wind including data on ion species which are currently difficult to track. It will also make possible remote sensing of the solar wind.

  16. Charged-current inclusive neutrino cross sections in the superscaling model including quasielastic, pion production and meson-exchange contributions

    NASA Astrophysics Data System (ADS)

    Ivanov, M. V.; Megias, G. D.; González-Jiménez, R.; Moreno, O.; Barbaro, M. B.; Caballero, J. A.; Donnelly, T. W.

    2016-08-01

    Charged current inclusive neutrino-nucleus cross sections are evaluated using the superscaling model for quasielastic scattering and its extension to the pion production region. The contribution of two-particle-two-hole vector meson-exchange current excitations is also considered within a fully relativistic model tested against electron scattering data. The results are compared with the inclusive neutrino-nucleus data from the T2K and SciBooNE experiments. For experiments where < {E}ν > ∼ 0.8 {{GeV}}, the three mechanisms considered in this work provide good agreement with the data. However, when the neutrino energy is larger, effects from beyond the Δ also appear to be playing a role. The results show that processes induced by vector two-body currents play a minor role in the inclusive cross sections at the kinematics considered.

  17. Analysis of x-ray emission spectra in charge-exchange collisions of C6 + with He and H2

    NASA Astrophysics Data System (ADS)

    Leung, Anthony C. K.; Kirchner, Tom

    2016-05-01

    Charge exchange in C6 +-He and -H2 collisions followed by x-ray emission is examined using the two-center basis generator method for low to intermediate projectile energies. Within the independent electron model, we calculate capture cross sections and perform a radiative cascade analysis to obtain Lyman line-emission ratios. Single capture is considered for the C6 +-He system, while both single capture and autoionizing double capture are considered for the C6 +-H2 system. Effects of a time-dependent screening potential that models target response on the l distribution of capture cross sections and the line-emission ratios are examined as well. Calculated line-emission ratios based on the no-response approximation are in satisfactory agreement with previous measurements.

  18. Energy exchange between a laser beam and charged particles using inverse transition radiation and method for its use

    DOEpatents

    Kimura, Wayne D.; Romea, Richard D.; Steinhauer, Loren C.

    1998-01-01

    A method and apparatus for exchanging energy between relativistic charged particles and laser radiation using inverse diffraction radiation or inverse transition radiation. The beam of laser light is directed onto a particle beam by means of two optical elements which have apertures or foils through which the particle beam passes. The two apertures or foils are spaced by a predetermined distance of separation and the angle of interaction between the laser beam and the particle beam is set at a specific angle. The separation and angle are a function of the wavelength of the laser light and the relativistic energy of the particle beam. In a diffraction embodiment, the interaction between the laser and particle beams is determined by the diffraction effect due to the apertures in the optical elements. In a transition embodiment, the interaction between the laser and particle beams is determined by the transition effect due to pieces of foil placed in the particle beam path.

  19. Cyclic voltammetry on sputter-deposited films of electrochromic Ni oxide: Power-law decay of the charge density exchange

    SciTech Connect

    Wen, Rui-Tao Granqvist, Claes G.; Niklasson, Gunnar A.

    2014-10-20

    Ni-oxide-based thin films were produced by reactive direct-current magnetron sputtering and were characterized by X-ray diffraction and Rutherford backscattering spectroscopy. Intercalation of Li{sup +} ions was accomplished by cyclic voltammetry (CV) in an electrolyte of LiClO{sub 4} in propylene carbonate, and electrochromism was documented by spectrophotometry. The charge density exchange, and hence the optical modulation span, decayed gradually upon repeated cycling. This phenomenon was accurately described by an empirical power law, which was valid for at least 10{sup 4} cycles when the applied voltage was limited to 4.1 V vs Li/Li{sup +}. Our results allow lifetime assessments for one of the essential components in an electrochromic device such as a “smart window” for energy-efficient buildings.

  20. The Ion-induced Charge-exchange X-ray Emission of the Jovian Auroras: Magnetospheric or Solar Wind Origin?

    SciTech Connect

    Hui, Yawei; Schultz, David Robert; Kharchenko, Vasili A; Stancil, Phillip C.; Cravens, Thomas E. E.; Lisse, Carey M.; Dalgarno, A.

    2009-01-01

    A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions ( 0.7-2 MeV/u), but infer a different relative sulfur to oxygen abundance ratio for these Chandra observations.

  1. THE ION-INDUCED CHARGE-EXCHANGE X-RAY EMISSION OF THE JOVIAN AURORAS: MAGNETOSPHERIC OR SOLAR WIND ORIGIN?

    SciTech Connect

    Hui Yawei; Schultz, David R.; Kharchenko, Vasili A.; Stancil, Phillip C.; Cravens, Thomas E.; Lisse, Carey M. E-mail: schultzd@ornl.gov E-mail: stancil@physast.uga.edu E-mail: carey.lisse@jhuapl.edu

    2009-09-10

    A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions ({approx}0.7-2 MeV u{sup -1}), but infer a different relative sulfur-to-oxygen abundance ratio for these Chandra observations.

  2. Cyclic voltammetry on sputter-deposited films of electrochromic Ni oxide: Power-law decay of the charge density exchange

    NASA Astrophysics Data System (ADS)

    Wen, Rui-Tao; Granqvist, Claes G.; Niklasson, Gunnar A.

    2014-10-01

    Ni-oxide-based thin films were produced by reactive direct-current magnetron sputtering and were characterized by X-ray diffraction and Rutherford backscattering spectroscopy. Intercalation of Li+ ions was accomplished by cyclic voltammetry (CV) in an electrolyte of LiClO4 in propylene carbonate, and electrochromism was documented by spectrophotometry. The charge density exchange, and hence the optical modulation span, decayed gradually upon repeated cycling. This phenomenon was accurately described by an empirical power law, which was valid for at least 104 cycles when the applied voltage was limited to 4.1 V vs Li/Li+. Our results allow lifetime assessments for one of the essential components in an electrochromic device such as a "smart window" for energy-efficient buildings.

  3. Optimization and application of cooled avalanche photodiodes for spectroscopic fluctuation measurements with ultra-fast charge exchange recombination spectroscopy

    NASA Astrophysics Data System (ADS)

    Truong, D. D.; Fonck, R. J.; McKee, G. R.

    2016-11-01

    The Ultra-Fast Charge Exchange Recombination Spectroscopy (UF-CHERS) diagnostic is a highly specialized spectroscopic instrument with 2 spatial channels consisting of 8 spectral channels each and a resolution of ˜0.25 nm deployed at DIII-D to measure turbulent ion temperature fluctuations. Charge exchange emissions are obtained between 528 and 530 nm with 1 μs time resolution to study plasma instabilities. A primary challenge of extracting fluctuation measurements from raw UF-CHERS signals is photon and electronic noise. In order to reduce dark current, the Avalanche Photodiode (APD) detectors are thermo-electrically cooled. State-of-the-art components are used for the signal amplifiers and conditioners to minimize electronic noise. Due to the low incident photon power (≤1 nW), APDs with a gain of up to 300 are used to optimize the signal to noise ratio. Maximizing the APDs' gain while minimizing the excess noise factor (ENF) is essential since the total noise of the diagnostic sets a floor for the minimum level of detectable broadband fluctuations. The APDs' gain should be high enough that photon noise dominates electronic noise, but not excessive so that the ENF overwhelms plasma fluctuations. A new generation of cooled APDs and optimized preamplifiers exhibits significantly enhanced signal-to-noise compared to a previous generation. Experiments at DIII-D have allowed for characterization and optimization of the ENF vs. gain. A gain of ˜100 at 1700 V is found to be near optimal for most plasma conditions. Ion temperature and toroidal velocity fluctuations due to the edge harmonic oscillation in quiescent H-mode plasmas are presented to demonstrate UF-CHERS' capabilities.

  4. Inclusive measurement of (p,. pi. /sup -/xn) double charge exchange reactions on bismuth from threshold to 800 MeV

    SciTech Connect

    Dombsky, M.; D'Auria, J.M.; Kelson, I.; Yavin, A.I.; Ward, T.E.; Clark, J.L.; Ruth, T.; Sheffer, G.

    1985-07-01

    The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,..pi../sup -/xn) double charge exchange reactions on bismuth (/sup 209/Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of /sup 211/At activity in thin (approx.1 mg/cm/sup 2/), irradiated bismuth targets. Calculations of the contributions of secondary (two-step) reactions to these measured astatine yields were performed, based partially upon the observed /sup 211/At activity although even at the highest energies, the contribution to products lighter than /sup 207/At was negligible. These data for products with as many as seven neutrons removed from the doubly coherent product (/sup 210/At) display nearly Gaussian shapes for the mass distributions of the astatine residues, with the maximum occurring for about /sup 204/At. The most probable momentum transfer deduced from these distributions for the initial ..pi../sup -/ production step was 335 MeV/c. The observed excitation functions display a behavior similar to that observed for the yield of /sup 210/Po from a (p,..pi../sup 0/) reaction on /sup 209/Bi, but radically different from that observed for inclusive ..pi../sup -/ reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ..pi../sup -/ emission which is observed for this double charge exchange reaction. This model reflects the opacity of a nucleus to a source of internal energetic protons.

  5. Charge exchange transition probability for collisions between unlike ions and atoms within the adiabatic approximation

    NASA Technical Reports Server (NTRS)

    Xu, Y. J.; Khandelwal, G. S.; Wilson, John W.

    1989-01-01

    A simple formula for the transition probability for electron exchange between unlike ions and atoms is established within the adiabatic approximation by employing the Linear Combination of Atomic Orbitals (LCAO) method. The formula also involves an adiabatic parameter, introduced by Massey, and thus the difficulties arising from the internal energy defect and the adiabatic approximation are avoided. Specific reactions Li(+++) + H to Li(++) + H(+) and Be(4+) + H to Be(3+) + H(+) are considered as examples. The calculated capture cross section results of the present work are compared with the experimental data and with the calculation of other authors over the velocity range of 10(7) cm/sec to 10(8) cm/sec.

  6. Loss of Sodium/Hydrogen Exchanger NHA2 Exacerbates Obesity- and Aging-Induced Glucose Intolerance in Mice

    PubMed Central

    Deisl, Christine; Anderegg, Manuel; Albano, Giuseppe; Lüscher, Benjamin P.; Cerny, David; Soria, Rodrigo; Bouillet, Elisa; Rimoldi, Stefano; Scherrer, Urs

    2016-01-01

    We previously demonstrated that the sodium/hydrogen exchanger NHA2, also known as NHEDC2 or SLC9B2, is critical for insulin secretion by β–cells. To gain more insights into the role of NHA2 on systemic glucose homeostasis, we studied the impact of loss of NHA2 during the physiological aging process and in the setting of diet-induced obesity. While glucose tolerance was normal at 2 months of age, NHA2 KO mice displayed a significant glucose intolerance at 5 and 12 months of age, respectively. An obesogenic high fat diet further exacerbated the glucose intolerance of NHA2 KO mice. Insulin levels remained similar in NHA2 KO and WT mice during aging and high fat diet, but fasting insulin/glucose ratios were significantly lower in NHA2 KO mice. Peripheral insulin sensitivity, measured by insulin tolerance tests and hyperinsulinemic euglycemic clamps, was unaffected by loss of NHA2 during aging and high fat diet. High fat diet diminished insulin secretion capacity in both WT and NHA2 KO islets and reduced expression of NHA2 in WT islets. In contrast, aging was characterized by a gradual increase of NHA2 expression in islets, paralleled by an increasing difference in insulin secretion between WT and NHA2 KO islets. In summary, our results demonstrate that loss of the sodium/hydrogen exchanger NHA2 exacerbates obesity- and aging-induced glucose intolerance in mice. Furthermore, our data reveal a close link between NHA2 expression and insulin secretion capacity in islets. PMID:27685945

  7. Asymptotic form of the charge exchange cross section in the three body rearrangement collisions

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1975-01-01

    A three body general rearrangement collision is considered where the initial and final bound states are described by the hydrogen-like wave functions. Mathematical models are developed to establish the relationships of quantum number, the reduced mass, and the nuclear charge of the final state. It is shown that for the low lying levels, the reciprocal of n cubed scaling law at all incident energies is only approximately satisfied. The case of the symmetric collisions is considered and it is shown that for high n and high incident energy, E, the cross section behaves as the reciprocal of E cubed. Zeros and minima in the differential cross sections in the limit of high n for protons on atomic hydrogen and positrons on atomic hydrogen are given.

  8. Modeling the magnetospheric X-ray emission from solar wind charge exchange with verification from XMM-Newton observations

    NASA Astrophysics Data System (ADS)

    Whittaker, Ian C.; Sembay, Steve; Carter, Jennifer A.; Read, Andrew M.; Milan, Steve E.; Palmroth, Minna

    2016-05-01

    An MHD-based model of terrestrial solar wind charge exchange (SWCX) is created and compared to 19 case study observations in the 0.5-0.7 keV emission band taken from the European Photon Imaging Cameras on board XMM-Newton. This model incorporates the Global Unified Magnetosphere-Ionosphere Coupling Simulation-4 MHD code and produces an X-ray emission datacube from O7+ and O8+ emission lines around the Earth using in situ solar wind parameters as the model input. This study details the modeling process and shows that fixing the oxygen abundances to a constant value reduces the variance when comparing to the observations, at the cost of a small accuracy decrease in some cases. Using the ACE oxygen data returns a wide ranging accuracy, providing excellent correlation in a few cases and poor/anticorrelation in others. The sources of error for any user wishing to simulate terrestrial SWCX using an MHD model are described here and include mask position, hydrogen to oxygen ratio in the solar wind, and charge state abundances. A dawn-dusk asymmetry is also found, similar to the results of empirical modeling. Using constant oxygen parameters, magnitudes approximately double that of the observed count rates are returned. A high accuracy is determined between the model and observations when comparing the count rate difference between enhanced SWCX and quiescent periods.

  9. Structure-property relationships in non-epitaxial chalcogenide heterostructures: the role of interface density on charge exchange

    NASA Astrophysics Data System (ADS)

    Bauers, S. R.; Ditto, J.; Moore, D. B.; Johnson, D. C.

    2016-07-01

    A homologous series of quasi-2D ([PbSe]1+δ)m(TiSe2)m nanolayered heterostructures are prepared via self-assembly of designed precursors with 1 <= m <= 4 and their structures and properties investigated. All heterostructures have the same global composition but vary in their interface density. X-ray diffraction and electron microscopy studies show that the structures consist of rock salt structured PbSe layers alternating with TiSe2 layers, and that grain size increases with m. The compounds are all metallic with upturns in resistivity at low temperature suggesting electron localization, with room temperature resistivity of 1-3 10-5 Ω m, negative Hall coefficients and Seebeck coefficients between -50 and -100 μV K-1. A decrease in the mobile carrier concentration with temperature is observed for all m and the rate increases with increasing low-dimensionality. Decreasing the interface density also decreases the average carrier concentration while increasing the electron mobility. The Seebeck coefficients systematically increase in magnitude as m is increased, but the net effect to the power factor is small due to a compensating increase in resistivity. The observed transport behavior is not described by the simple rigid band models with charge transfer between constituents used previously. Charge exchange between constituents stabilizes the intergrowth, but also introduces mobile carriers and interfacial band bending that must play a role in the transport behavior of the heterostructures. As chemical potentials equilibrate in high m heterostructures there is a decrease in total coulombic stabilization as there are fewer interfaces, so m = 1 is likely to be most stable. This rationalizes why the structurally similar misfit layer compounds with m = 1 are often the only intergrowths that can be prepared. Charge transfer and band bending at interfaces should occur in other heterostructures with similar type II broken-gap band alignments and are important

  10. Ultracold magnetically tunable interactions without radiative-charge-transfer losses between Ca+, Sr+, Ba+, and Yb+ ions and Cr atoms

    NASA Astrophysics Data System (ADS)

    Tomza, Michał

    2015-12-01

    The Ca+, Sr+, Ba+, and Yb+ ions immersed in an ultracold gas of the Cr atoms are proposed as experimentally feasible heteronuclear systems in which ion-atom interactions at ultralow temperatures can be controlled with magnetically tunable Feshbach resonances without charge transfer and radiative losses. Ab initio techniques are applied to investigate electronic-ground-state properties of the (CaCr)+, (SrCr)+, (BaCr)+, and (YbCr)+ molecular ions. The potential energy curves, permanent electric dipole moments, and static electric dipole polarizabilities are computed. The spin-restricted open-shell coupled-cluster method restricted to single, double, and noniterative triple excitations and the multireference configuration-interaction method restricted to single and double excitations are employed. The scalar relativistic effects are included within the small-core energy-consistent pseudopotentials. The leading long-range induction and dispersion interaction coefficients are also reported. Finally, magnetic Feshbach resonances between the Ca+, Sr+, Ba+, and Yb+ ions interacting with the Cr atoms are analyzed. The present proposal opens the way towards robust quantum simulations and computations with ultracold ion-atom systems free of radiative charge-transfer losses.

  11. Proton exchange membrane fuel cell reversible performance loss induced by carbon monoxide produced during operation

    NASA Astrophysics Data System (ADS)

    Decoopman, B.; Vincent, R.; Rosini, S.; Paganelli, G.; Thivel, P.-X.

    2016-08-01

    Cyclic voltammetry measurements at the anode have been carried out and reveal the presence of carbon monoxide in steady-state operation, with pure hydrogen. Experiments have been performed both in single cell and in stack to find out its origin. The contamination of the anode catalyst is partly due the reverse-water gas shift (RWGS) with carbon dioxide from the cathode. However, this study shows a temperature-activated and time-related corrosion mechanism which appears under humidified hydrogen. Due to this degradation mechanism, a reversible 25 mV-loss of performances is observed and can be recovered by oxidizing carbon monoxide on the anode.

  12. Proton exchange membrane fuel cell reversible performance loss induced by carbon monoxide produced during operation

    NASA Astrophysics Data System (ADS)

    Decoopman, B.; Vincent, R.; Rosini, S.; Paganelli, G.; Thivel, P.-X.

    2016-08-01

    Cyclic voltammetry measurements at the anode have been carried out and reveal the presence of carbon monoxide in steady-state operation, with pure hydrogen. Experiments have been performed both in single cell and in stack to find out its origin. The contamination of the anode catalyst is partly due the reverse-water gas shift (RWGS) with carbon dioxide from the cathode. However, this study shows a temperature-activated and time-related corrosion mechanism which appears under humidified hydrogen. Due to this degradation mechanism, a reversible 25 mV-loss of performances is observed and can be recovered by oxidizing carbon monoxide on the anode.

  13. The Uranian corona as a charge exchange cascade of plasma sheet protons

    NASA Astrophysics Data System (ADS)

    Herbert, F.

    1993-03-01

    The paper uses models of magnetic convection and interparticle interactions to examine the collisional interactions between atmospheric neutral hydrogen and magnetospheric charged particles observed by Voyager to be convecting through the Uranian magnetosphere. The e(-)-H collisional ionization process, continually reenergized by compressional heating of the electrons as they drift toward Uranus, produces a cascade of new plasma. This process has been suggested elsewhere as the source of the warm (10 eV at L = 5) plasma and is found in the present study to continue in a cascade to even cooler and more abundant plasma. This newly created plasma consists almost entirely of electrons and protons because He and H2 are nearly absent from the uppermost layers of the atmosphere. If this plasma crosses the dayside magnetopause and mixes with magnetopause boundary layers such as the plasma mantle, there to be swept back along the magnetotail, reincorporated into the magnetotail by the same processes postulated for solar wind plasma entry, and reenergized in the magnetotail current sheet, it would constitute an important source for the hot plasma observed by Voyager.

  14. Restoration of Na+/H+ exchanger NHE3-containing macrocomplexes ameliorates diabetes-associated fluid loss

    PubMed Central

    He, Peijian; Zhao, Luqing; Zhu, Lixin; Weinman, Edward J.; De Giorgio, Roberto; Koval, Michael; Srinivasan, Shanthi; Yun, C. Chris

    2015-01-01

    Diarrhea is one of the troublesome complications of diabetes, and the underlying causes of this problem are complex. Here, we investigated whether altered electrolyte transport contributes to diabetic diarrhea. We found that the expression of Na+/H+ exchanger NHE3 and several scaffold proteins, including NHE3 regulatory factors (NHERFs), inositol trisphosphate (IP3) receptor-binding protein released with IP3 (IRBIT), and ezrin, was decreased in the intestinal brush border membrane (BBM) of mice with streptozotocin-induced diabetes. Treatment of diabetic mice with insulin restored intestinal NHE3 activity and fluid absorption. Molecular analysis revealed that NHE3, NHERF1, IRBIT, and ezrin form macrocomplexes, which are perturbed under diabetic conditions, and insulin administration reconstituted these macrocomplexes and restored NHE3 expression in the BBM. Silencing of NHERF1 or IRBIT prevented NHE3 trafficking to the BBM and insulin-dependent NHE3 activation. IRBIT facilitated the interaction of NHE3 with NHERF1 via protein kinase D2–dependent phosphorylation. Insulin stimulated ezrin phosphorylation, which enhanced the interaction of ezrin with NHERF1, IRBIT, and NHE3. Additionally, oral administration of lysophosphatidic acid (LPA) increased NHE3 activity and fluid absorption in diabetic mice via an insulin-independent pathway. Together, these findings indicate the importance of NHE3 in diabetic diarrhea and suggest LPA administration as a potential therapeutic strategy for management of diabetic diarrhea. PMID:26258413

  15. Loss of Homeostatic Gas Exchange in Eastern Hemlock in Response to Pollution and Rising CO2?

    NASA Astrophysics Data System (ADS)

    Rayback, S. A.; Gagen, M. H.; Lini, A.; Cogbill, C. V.

    2014-12-01

    In eastern North American, multiple environmental effects, natural and anthropogenic, may impinge upon tree-ring based stable carbon isotope ratios when examined over long time periods. Investigation of relationships between a Vermont (USA) eastern hemlock δ¹³C (1849-2010) chronology and local and regional climate variables, as well as a regional sulfur dioxide time series revealed the decoupling of δ¹³C from significant climate drivers such as May-August maximum temperature (r=0.50, p<0.01) and, raise the possibility that this decoupling can be attributed to foliar and soil leaching of calcium due to acidic deposition since the 1960s. Further, investigation of derived photosynthetic isotope discrimination (Δ¹³C) time series showed an overall decreasing trend in Δ¹³C in response to rising atmospheric carbon dioxide (ca), but with a slight rise in Δ¹³C in the last decade. Comparison of time series of leaf intercellular CO2 concentration (ci), ci/ca, and intrinsic water use efficiency (iWUE) showed homeostatic maintenance of ci levels against ca until 1965 and rising iWUE. Then, ci increased proportional (1965-2000) and later at the same rate as ca (2001-2010) and iWUE leveled off indicating a potential loss of sensitivity to increasing atmospheric carbon dioxide. This more recent passive response may be an indication of a loss of homeostatic maintenance of stomatal control and/or may be linked to changing climate in the region (e.g., wetter conditions).

  16. Loss of the AE3 Anion Exchanger in a Hypertrophic Cardiomyopathy Model Causes Rapid Decompensation and Heart Failure

    PubMed Central

    Al Moamen, Nabeel J.; Prasad, Vikram; Bodi, Ilona; Miller, Marian L.; Neiman, Michelle L.; Lasko, Valerie M.; Alper, Seth L.; Wieczorek, David F.; Lorenz, John N.; Shull, Gary E.

    2010-01-01

    The AE3 Cl−/HCO3− exchanger is abundantly expressed in the sarcolemma of cardiomyocytes, where it mediates Cl−-uptake and HCO3−-extrusion. Inhibition of AE3-mediated Cl−/HCO3− exchange has been suggested to protect against cardiac hypertrophy; however, other studies indicate that AE3 might be necessary for optimal cardiac function. To test these hypotheses we crossed AE3-null mice, which appear phenotypically normal, with a hypertrophic cardiomyopathy mouse model carrying a Glu180Gly mutation in α–tropomyosin (TM180). Loss of AE3 had no effect on hypertrophy; however, survival of TM180/AE3 double mutants was sharply reduced compared with TM180 single mutants. Analysis of cardiac performance revealed impaired cardiac function in TM180 and TM180/AE3 mutants. TM180/AE3 double mutants were more severely affected and exhibited little response to β-adrenergic stimulation, a likely consequence of their more rapid progression to heart failure. Increased expression of calmodulin-dependent kinase II and protein phosphatase 1 and differences in methylation and localization of protein phosphatase 2A were observed, but were similar in single and double mutants. Phosphorylation of phospholamban on Ser16 was sharply increased in both single and double mutants relative to wild-type hearts under basal conditions, leading to reduced reserve capacity for β-adrenergic stimulation of phospholamban phosphorylation. Imaging analysis of isolated myocytes revealed reductions in amplitude and decay of Ca2+ transients in both mutants, with greater reductions in TM180/AE3 mutants, consistent with the greater severity of their heart failure phenotype. Thus, in the TM180 cardiomyopathy model, loss of AE3 had no apparent anti-hypertrophic effect and led to more rapid decompensation and heart failure. PMID:21056571

  17. The effect of discontinuous gas exchange on respiratory water loss in grasshoppers (Orthoptera: Acrididae) varies across an aridity gradient.

    PubMed

    Huang, Shu-Ping; Talal, Stav; Ayali, Amir; Gefen, Eran

    2015-08-01

    The significance of discontinuous gas-exchange cycles (DGC) in reducing respiratory water loss (RWL) in insects is contentious. Results from single-species studies are equivocal in their support of the classic 'hygric hypothesis' for the evolution of DGC, whereas comparative analyses generally support a link between DGC and water balance. In this study, we investigated DGC prevalence and characteristics and RWL in three grasshopper species (Acrididae, subfamily Pamphaginae) across an aridity gradient in Israel. In order to determine whether DGC contributes to a reduction in RWL, we compared the DGC characteristics and RWL associated with CO2 release (transpiration ratio, i.e. the molar ratio of RWL to CO2 emission rates) among these species. Transpiration ratios of DGC and continuous breathers were also compared intraspecifically. Our data show that DGC characteristics, DGC prevalence and the transpiration ratios correlate well with habitat aridity. The xeric-adapted Tmethis pulchripennis exhibited a significantly shorter burst period and lower transpiration ratio compared with the other two mesic species, Ocneropsis bethlemita and Ocneropsis lividipes. However, DGC resulted in significant water savings compared with continuous exchange in T. pulchripennis only. These unique DGC characteristics for T. pulchripennis were correlated with its significantly higher mass-specific tracheal volume. Our data suggest that the origin of DGC may not be adaptive, but rather that evolved modulation of cycle characteristics confers a fitness advantage under stressful conditions. This modulation may result from morphological and/or physiological modifications. PMID:26290590

  18. Method development for the separation of monoclonal antibody charge variants in cation exchange chromatography, Part I: salt gradient approach.

    PubMed

    Fekete, Szabolcs; Beck, Alain; Fekete, Jenő; Guillarme, Davy

    2015-01-01

    Ion exchange chromatography (IEX) is a historical technique widely used for the detailed characterization of therapeutic proteins and can be considered as a reference and powerful technique for the qualitative and quantitative evaluation of charge variants. When applying salt gradient IEX approach for monoclonal antibodies (mAbs) characterization, this approach is described as time-consuming to develop and product-specific. The goal of this study was to tackle these two bottle-necks. By modeling the retention of several commercial mAbs and their variants in IEX, we proved that the mobile phase temperature was not relevant for tuning selectivity, while optimal salt gradient program can be easily found based on only two initial gradients of different slopes. Last but not least, the dependence of retention vs. pH being polynomial, three initial runs at different pH were required to optimize mobile phase pH. Finally, only 9h of initial experiments were necessary to simultaneously optimize salt gradient profile and pH in IEX. The data can then be treated with commercial modeling software to find out the optimal conditions to be used, and accuracy of retention times prediction was excellent (less than 1% variation between predicted and experimental values). Second, we also proved that generic IEX conditions can be applied for the characterization of mAbs possessing a wide range of pI, from 6.7 to 9.1. For this purpose, a strong cation exchange column has to be employed at a pH below 6 and using a proportion of NaCl up to 0.2M. Under these conditions, all the mAbs were properly eluted from the column. Therefore, salt gradient CEX can be considered as a generic multi-product approach. PMID:25240157

  19. New Measurements of the Solar Wind Charge Exchange, Local Bubble, and Halo 3/4 keV Emission from XMM-Newton and Suzaku Shadowing Observations

    NASA Astrophysics Data System (ADS)

    Shelton, Robin L.; Henley, David

    2016-06-01

    We report on the analyses of XMM-Newton and/or Suzaku observations of 6 on-cloud and off-cloud shadowing pairs. This study provides the first analysis of two of these pairs and the first uniform analysis of the larger dataset. For every shadowing pair, we determined the foreground and halo components by simultaneously fitting the spectra from both members of the pair with a model that included a foreground component and an absorbed background component. In the past, foreground X-ray emission was thought to come from the Local Bubble of hot gas surrounding the solar neighborhood and so thermal spectral models were used. Now that solar wind charge exchange is recognized as a source of foreground X-ray photons, it is appropriate to consider charge exchange models as well. For this reason, we repeated the analyses using one of 3 possible foreground models: a charge exchange spectral model whose line ratios come from atomic physics calculations and are presented in Cumbee et al. (2014), a charge exchange model based on the AtomDB Charge Exchange code, or a thermal spectrum. The analyses of the larger dataset enabled us to place an upper limit on the Local Bubble's O VII contribution, provide measurements of the local and halo contributions in the 0.4 to 1.0 keV band, comment on the abilities of the various solar wind models to fit the data, and comment on the sensitivity of the fit parameters to the choice of foreground model, metal abundance tables, and X-ray observatory.

  20. Charge Exchange-induced X-Ray Emission of Fe xxv and Fe xxvI via a Streamlined Model

    NASA Astrophysics Data System (ADS)

    Mullen, P. D.; Cumbee, R. S.; Lyons, D.; Stancil, P. C.

    2016-06-01

    Charge exchange (CX) is an important process for the modeling of X-ray spectra obtained by the Chandra, XMM-Newton, and Suzaku X-ray observatories, as well as the anticipated Astro-H mission. The understanding of the observed X-ray spectra produced by many astrophysical environments is hindered by the current incompleteness of available atomic and molecular data—especially for CX. Here, we implement a streamlined program set that applies quantum defect methods and the Landau-Zener theory to generate total, n-resolved, and n{\\ell }S-resolved cross sections for any given projectile ion/target CX collision. By using these data in a cascade model for X-ray emission, theoretical spectra for such systems can be predicted. With these techniques, Fe25+ and Fe26+ CX collisions with H, He, H2, N2, H2O, and CO are studied for single-electron capture (SEC). These systems have been selected because they illustrate computational difficulties for high projectile charges. Furthermore, Fe xxv and Fe xxvi emission lines have been detected in the Galactic center and Galactic ridge. Theoretical X-ray spectra for these collision systems are compared to experimental data generated by an electron-beam ion trap study. Several ℓ-distribution models have been tested for Fe25+ and Fe26+ SEC. Such analyses suggests that commonly used ℓ-distribution models struggle to accurately reflect the true distribution of electron capture as understood by more advanced theoretical methods.

  1. Exchange of chromosomal and plasmid alleles in Escherichia coli by selection for loss of a dominant antibiotic sensitivity marker.

    PubMed Central

    Russell, C B; Dahlquist, F W

    1989-01-01

    Transfer of an allele from a donor DNA to a recipient DNA molecule was selected by the loss of a dominant conditional lethal mutation previously incorporated ito the gene of interest in the recipient DNA. Both the Escherichia coli chromosome and plasmids carrying E. coli genes were used successfully as donor molecules. Recipient molecules for these exchanges were constructed in vitro by using the rpsL gene, which confers sensitivity to streptomycin, to replace segments of specific E. coli genes located either on multicopy plasmids or in the E. coli chromosome. Plasmids carrying such replacements were capable of acquiring chromosomal alleles of the gene(s) of interest, and strains carrying rpsL replacements in the chromosome were capable of acquiring plasmid-encoded alleles at the sight of the rpsL replacement. In both situations, these allele transfers resulted in loss of the rpsL gene from the recipient DNA molecule. The desired transfer events constituted a large percentage of these events, which gave rise to viable colonies when appropriate donor-recipient pairs were subjected to streptomycin selection. Thus, this is a useful approach for transferring alleles of interest from plasmids to the E. coli chromosome and vice versa. PMID:2651409

  2. A Combined Desorption Ionization by Charge Exchange (DICE) and Desorption Electrospray Ionization (DESI) Source for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Chan, Chang-Ching; Bolgar, Mark S.; Miller, Scott A.; Attygalle, Athula B.

    2011-01-01

    A source that couples the desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) techniques together was demonstrated to broaden the range of compounds that can be analyzed in a single mass spectrometric experiment under ambient conditions. A tee union was used to mix the spray reagents into a partially immiscible blend before this mixture was passed through a conventional electrospray (ES) probe capillary. Using this technique, compounds that are ionized more efficiently by the DICE method and those that are ionized better with the DESI procedure could be analyzed simultaneously. For example, hydroquinone, which is not detected when subjected to DESI-MS in the positive-ion generation mode, or the sodium adduct of guaifenesin, which is not detected when examined by DICE-MS, could both be detected in one experiment when the two techniques were combined. The combined technique was able to generate the molecular ion, proton and metal adduct from the same compound. When coupled to a tandem mass spectrometer, the combined source enabled the generation of product ion spectra from the molecular ion and the [M + H]+ or [M + metal]+ ions of the same compound without the need to physically change the source from DICE to DESI. The ability to record CID spectra of both the molecular ion and adduct ions in a single mass spectrometric experiment adds a new dimension to the array of mass spectrometric methods available for structural studies.

  3. Compact multichannel neutral particle analyzer for measurement of energetic charge-exchanged neutrals in Alcator C-Mod

    SciTech Connect

    Tang, V.; Liptac, J.; Parker, R. R.; Bonoli, P. T.; Fiore, C. L.; Granetz, R. S.; Irby, J. H.; Lin, Y.; Wukitch, S. J.; Frenje, J. A.; Leiter, R.; Mcduffee, S.; Petrasso, R. D.

    2006-08-15

    A four-channel compact neutral particle analyzer (CNPA) based on operating small Si diode detectors in pulse-height analysis (PHA) mode is used to measure energetic hydrogen minority ions with energies between {approx}50 and 350 keV stemming from ion-cyclotron range-of-frequency heated D(H) Alcator C-Mod plasmas with both active and passive charge exchange (CX). First core minority ion distribution results from Alcator C-Mod discharges and a detailed description of the diagnostic are presented. The diagnostic employs integrated electronics and fast digitization of the shaping amplifier voltage. The digitized data are stored for postshot PHA, which removes the constraints of real-time PHA and allows for improved performance via elimination of base line shift effects and potentially relieving pileup through Gaussian fitting routines. The CNPA is insensitive to the large gamma and neutron background in Alcator C-Mod discharges but is susceptible to the plasma's soft x-ray flux. The soft x-ray flux limits the CNPA energy resolution to {approx}15-20 keV. A simple model is used to interpret the active CNPA data which permits rapid estimates of the core hydrogen minority temperatures and anisotropy with a time resolution of {approx}100 ms. Hydrogenlike boron is identified as an important electron donor for the CX signal.

  4. Analysis of x-ray emission in charge-exchange collisions of C6+ ions with He and H2

    NASA Astrophysics Data System (ADS)

    Leung, Anthony C. K.; Kirchner, T.

    2016-05-01

    Charge exchange in C6+-He and - H2 collisions followed by x-ray emission is examined using the two-center basis generator method within the independent electron model. The analysis examines the two collision systems for low to intermediate projectile energies. We perform capture cross section and radiative cascade calculations to obtain Lyman line emission ratios which can be compared to measurements that were carried out at the Oak Ridge National Laboratory Multicharged Ion Research Facility. Single-electron capture is considered for the C6+-He system while both single and autoionizing double capture are considered for the C6+- H2 system. We also examine the effects of a time-dependent screening potential that models target response on the l distribution of the capture cross sections and the emission ratios. Calculated line emission ratios based on the no-response approximation are found to be in satisfactory agreement with the measurements. Work supported by SHARCNET, OGS, and NSERC, Canada

  5. Using (18)O/(16)O exchange to probe an equilibrium space-charge layer at the surface of a crystalline oxide: method and application.

    PubMed

    De Souza, Roger A; Martin, Manfred

    2008-05-01

    The use of an (18)O/(16)O exchange experiment as a means for probing surface space-charge layers in oxides is examined theoretically and experimentally. On the basis of a theoretical treatment, isotope penetration profiles are calculated for (18)O/(16)O exchange across a gas-solid interface and subsequent diffusion of the labelled isotope through an equilibrium space-charge layer depleted of mobile oxygen vacancies and into a homogeneous bulk phase. Profiles calculated for a range of conditions all have a characteristic shape: a sharp drop in isotope fraction close to the surface followed by a normal bulk diffusion profile. Experimental (18)O profiles in an exchanged (001) oriented single crystal of Fe-doped SrTiO(3) were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS). By extracting the space-charge potential from such profiles, we demonstrate that this method allows the spatially resolved characterization of space-charge layers at the surfaces of crystalline oxides under thermodynamically well-defined conditions.

  6. Observations of net soil exchange of CO2 in a dryland show experimental warming increases carbon losses in biocrust soils

    USGS Publications Warehouse

    Darrouzet-Nardi, Anthony N.; Reed, Sasha C.; Grote, Ed; Belnap, Jayne

    2015-01-01

    Many arid and semiarid ecosystems have soils covered with well-developed biological soil crust communities (biocrusts) made up of mosses, lichens, cyanobacteria, and heterotrophs living at the soil surface. These communities are a fundamental component of dryland ecosystems, and are critical to dryland carbon (C) cycling. To examine the effects of warming temperatures on soil C balance in a dryland ecosystem, we used infrared heaters to warm biocrust-dominated soils to 2 °C above control conditions at a field site on the Colorado Plateau, USA. We monitored net soil exchange (NSE) of CO2 every hour for 21 months using automated flux chambers (5 control and 5 warmed chambers), which included the CO2 fluxes of the biocrusts and the soil beneath them. We observed measurable photosynthesis in biocrust soils on 12 % of measurement days, which correlated well with precipitation events and soil wet-up. These days included several snow events, providing what we believe to be the first evidence of substantial photosynthesis underneath snow by biocrust organisms in drylands. Overall, biocrust soils in both control and warmed plots were net CO2 sources to the atmosphere, with control plots losing 62 ± 8 g C m−2 (mean ± SE) over the first year of measurement and warmed plots losing 74 ± 9 g C m−2. Between control and warmed plots, the difference in soil C loss was uncertain over the course of the entire year due to large and variable rates in spring, but on days during which soils were wet and crusts were actively photosynthesizing, biocrusts that were warmed by 2 °C had a substantially more negative C balance (i.e., biocrust soils took up less C and/or lost more C in warmed plots). Taken together, our data suggest a substantial risk of increased C loss from biocrust soils with higher future temperatures, and highlight a robust capacity to predict CO2 exchange in biocrust soils using easily measured environmental parameters.

  7. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Astrophysics Data System (ADS)

    Chutjian, A.; Smith, Steven J.; Lozano, J. A.

    2002-11-01

    There is increasing emphasis within this decade on understanding energy balance and new phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, and the X-ray spectral return from the HETG on Chandra and the LETGS on XMM-Newton are just beginning. The line emissions are almost entirely from highly-charged ions (HCIs) of C, N, O, Ne, Mg, S, Si, Ca, and Fe. In addition, the Constellation-X mission, currently in the planning stages, will provide high-throughput X-ray spectroscopy up to photon energies of 0.12 nm (10 keV), where the primary line emitters will again be the HCIs. This array of space instruments is providing an overwhelming return of HCI spectral data from a variety of astrophysical objects. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma [1]. The JPL electron energy-loss and merged-beams approach [2] has been used to measure absolute collision strengths in a number of ions, with critical comparisons to the best available theories. Experimental methods will be reviewed, and results presented on experimental comparisons to R-Matrix and Breit-Pauli theoretical results in C3+[3], O2+[4], O5+[5], S2+[6], and Fe9+ [7]. Work is planned for comparisons in Mgq+, and higher charge states Fe(10-15)+. J. Lozano thanks the National Research Council for a fellowship though the NASA- NRC program. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and was supported under contract with the National Aeronautics and Space Administration.

  8. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    NASA Technical Reports Server (NTRS)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  9. Real and hypothetical endowment effects when exchanging lottery tickets: Is regret a better explanation than loss aversion?

    PubMed

    Kogler, Christoph; Kühberger, Anton; Gilhofer, Rainer

    2013-08-01

    The endowment effect is the finding that possession of an item adds to its value. We introduce a new procedure for testing this effect: participants are divided into two groups. Possession group participants inspect a numbered lottery ticket and know it is theirs, while inspection group participants only inspect a lottery ticket without being endowed with it. Subsequently participants choose between playing the lottery with this (possessed or inspected) ticket, or exchanging it for another one. Our procedure tests for the effect of endowment while controlling for the influence of transaction costs as well as for inspection effects and the influence of bargaining roles (buyer vs. seller), which often afflict experimentation with the endowment effect. In a real setting, tickets in possession were valued significantly higher than inspected tickets. Contrary to some findings in the literature participants also correctly predicted these valuation differences in a hypothetical situation, both for themselves as well as for others. Furthermore, our results suggest that regret rather than loss aversion may be the source of the endowment effect in an experimental setting using lottery tickets. Applying our procedure to a setting employing riskless objects in form of mugs revealed rather ambiguous results, thus emphasizing that the role of regret might be less prominent in non-lottery settings. PMID:23913998

  10. Cross section for Rydberg antihydrogen production via charge exchange between Rydberg positroniums and antiprotons in a magnetic field

    NASA Astrophysics Data System (ADS)

    Krasnický, D.; Caravita, R.; Canali, C.; Testera, G.

    2016-08-01

    The antihydrogen formation by charge exchange between cold antiprotons and Rydberg positronium Ps* is studied by using the classical trajectory Monte Carlo method. In the absence of external magnetic field the cross section scaled by the fourth power of the Ps* principal quantum number nPs shows a universal behavior as a function of the ratio kv between the velocity of the Ps center of mass and that of the positron in the classical circular orbit. At low velocity, below about kv≃0.2 -0.3 , we show for Rydberg positronium that the cross section increases as 1 /kv2 or, in an equivalent way, as 1 /EPs cm with EPs cm being the Ps* center-of-mass energy. In this regime the distribution of the principal quantum number of the antihydrogen state is narrow and it shows a peak at about √{2}nPs while at higher kv values a broad distribution of antihydrogen states is produced. The study of the collision process in the presence of moderate magnetic field (0.5-2 T) shows that there is an experimentally interesting region of kv with the cross section slightly higher than that in the absence of field. However the presence of a magnetic field changes significantly the cross section behavior as a function of kv, especially at low velocities, where reductions of the cross sections and deviations from the 1 /kv2 (1 /EPs cm) are observed. Our calculations show a dependance of the cross section upon the angle between the magnetic field and the flight direction of the incoming Ps*.

  11. Core-ion temperature measurement of the ADITYA tokamak using passive charge exchange neutral particle energy analyzer

    SciTech Connect

    Pandya, Santosh P.; Ajay, Kumar; Mishra, Priyanka; Dhingra, Rajani D.; Govindarajan, J.

    2013-02-15

    Core-ion temperature measurements have been carried out by the energy analysis of passive charge exchange (CX) neutrals escaping out of the ADITYA tokamak plasma (minor radius, a= 25 cm and major radius, R= 75 cm) using a 45 Degree-Sign parallel plate electrostatic energy analyzer. The neutral particle analyzer (NPA) uses a gas cell configuration for re-ionizing the CX-neutrals and channel electron multipliers (CEMs) as detectors. Energy calibration of the NPA has been carried out using ion-source and {Delta}E/E of high-energy channel has been found to be {approx}10%. Low signal to noise ratio (SNR) due to VUV reflections on the CEMs was identified during the operation of the NPA with ADITYA plasma discharges. This problem was rectified by upgrading the system by incorporating the additional components and arrangements to suppress VUV radiations and improve its VUV rejection capabilities. The noise rejection capability of the NPA was experimentally confirmed using a standard UV-source and also during the plasma discharges to get an adequate SNR (>30) at the energy channels. Core-ion temperature T{sub i}(0) during flattop of the plasma current has been measured to be up to 150 eV during ohmically heated plasma discharges which is nearly 40% of the average core-electron temperature (typically T{sub e}(0) {approx} 400 eV). The present paper describes the principle of tokamak ion temperature measurement, NPA's design, development, and calibration along with the modifications carried out for minimizing the interference of plasma radiations in the CX-spectrum. Performance of the NPA during plasma discharges and experimental results on the measurement of ion-temperature have also been reported here.

  12. Multifluid Modeling of the Partially Ionized Chromosphere with Effects of Impact Ionization, Radiative Recombination and Charge Exchange

    NASA Astrophysics Data System (ADS)

    Maneva, Y. G.; Poedts, D. S.; Alvarez Laguna, A.; Lani, A.

    2015-12-01

    Neutrals play an important role in the evolution of the weakly ionized solar chromosphere where the number density of neutrals can vastly exceed the number density of protons. Therefore modeling the neutral-ion interactions and studying the effect of neutrals on the ambient plasma properties is an important task for better understanding the observed emission lines and the propagation of disturbances from the photosphere to the transition region and the corona. To pursue this goal we have developed two-fluid and three-fluid simulation setups to study the interaction between electrons, ions and neutrals in a reactive gravitationally stratified collisional media. The model considers the electrons and ions within the resistive MHD approach with Coulomb collisions and anisotropic heat flux determined by Braginskii's transport coefficients. The electromagnetic fields are evolved according to the full Maxwell equations, allowing for propagation of higher frequency waves neglected by the standard MHD approximation. Separate mass, momentum and energy conservation equations are considered for the neutrals and the interaction between the different fluids is determined by the chemical reactions, such as impact ionization, radiative recombination and charge exchange, provided as additional source terms. To initialize the system we consider an ideal gas equation of state with equal initial temperatures for the electrons, ions and the neutrals and different density profiles. The initial temperature and density profiles are height-dependent and follow VAL C atmospheric model for the solar chromosphere. We have searched for a chemical and collisional equilibrium between the ions and the neutrals in the hydrostatic case to avoid unphysical outflows and artificial heating induced by initial pressure imbalances. Next we consider ion-neutral interactions in magnetized plasma with an initial magnetic profile, corresponding to emerging magnetic funnel. Finally we include an external

  13. Cross section for Rydberg antihydrogen production via charge exchange between Rydberg positroniums and antiprotons in a magnetic field

    NASA Astrophysics Data System (ADS)

    Krasnický, D.; Caravita, R.; Canali, C.; Testera, G.

    2016-08-01

    The antihydrogen formation by charge exchange between cold antiprotons and Rydberg positronium Ps* is studied by using the classical trajectory Monte Carlo method. In the absence of external magnetic field the cross section scaled by the fourth power of the Ps* principal quantum number nPs shows a universal behavior as a function of the ratio kv between the velocity of the Ps center of mass and that of the positron in the classical circular orbit. At low velocity, below about kv≃0.2 -0.3 , we show for Rydberg positronium that the cross section increases as 1 /kv2 or, in an equivalent way, as 1 /EPs cm with EPs cm being the Ps* center-of-mass energy. In this regime the distribution of the principal quantum number of the antihydrogen state is narrow and it shows a peak at about √{2}nPs while at higher kv values a broad distribution of antihydrogen states is produced. The study of the collision process in the presence of moderate magnetic field (0.5-2 T) shows that there is an experimentally interesting region of kv with the cross section slightly higher than that in the absence of field. However the presence of a magnetic field changes significantly the cross section behavior as a function of kv, especially at low velocities, where reductions of the cross sections and deviations from the 1 /kv2 (1 /EPs cm) are observed. Our calculations show a dependance of the cross section upon the angle between the magnetic field and the flight direction of the incoming Ps*.

  14. The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble.

    PubMed

    Galeazzi, M; Chiao, M; Collier, M R; Cravens, T; Koutroumpa, D; Kuntz, K D; Lallement, R; Lepri, S T; McCammon, D; Morgan, K; Porter, F S; Robertson, I P; Snowden, S L; Thomas, N E; Uprety, Y; Ursino, E; Walsh, B M

    2014-08-14

    The solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays, coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a 'local cavity' filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar-wind charge-exchange contribution is approximately 40 per cent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun. PMID:25079321

  15. Classical description of H(1 s ) and H*(n =2 ) for cross-section calculations relevant to charge-exchange diagnostics

    NASA Astrophysics Data System (ADS)

    Cariatore, N. D.; Otranto, S.; Olson, R. E.

    2015-04-01

    In this work, we introduce a classical trajectory Monte Carlo (CTMC) methodology, specially conceived to provide a more accurate representation of charge-exchange processes between highly charged ions and H (1 s ) and H*(n=2 ) . These processes are of particular relevance in power fusion reactor programs, for which charge-exchange spectroscopy has become a useful plasma diagnostics tool. To test the methodology, electron-capture reactions from these targets by 6C ,7+N, and 8+O are studied at impact energies in the 10 -150 keV/amu range. State-selective cross sections are contrasted with those predicted by the standard microcanonical formulation of the CTMC method, the CTMC method with an energy variation of initial binding energies that produces an improved radial electron density, and the atomic orbital close-coupling method. The present results are found in to be much better agreement with the quantum-mechanical results than the results of former formulations of the CTMC method.

  16. Communication: variational many-body expansion: accounting for exchange repulsion, charge delocalization, and dispersion in the fragment-based explicit polarization method.

    PubMed

    Gao, Jiali; Wang, Yingjie

    2012-02-21

    A fragment-based variational many-body (VMB) expansion method is described to directly account for exchange repulsion, charge delocalization (charge transfer) and dispersion interactions in the explicit polarization (X-Pol) method. The present VMB/X-Pol approach differs from other fragment molecular orbital (FMO) techniques in two major aspects. First, the wave function for the monomeric system is variationally optimized using standard X-Pol method, as opposed to the iterative update procedure adopted in FMO. Second, the mutual polarizations in the dimeric terms are also variationally determined, whereas single-point energy calculations of the individual dimers embedded in a static monomer field are used in FMO. The second-order (two-body) VMB (VMB2) expansion method is illustrated on a series of water hexamer complexes and one decamer cluster, making use of Hartree-Fock theory, MP2, and the PBE1 and M06 density functionals to represent the monomer and dimer fragments. The computed binding energies are within 2 kcal/mol of the corresponding results from fully delocalized calculations. Energy decomposition analyses reveal specific dimeric contributions to exchange repulsion, charge delocalization, and dispersion. Since the wave functions for one-body and all two-body terms are variationally optimized in VMB2 and X-Pol, it is straightforward to obtain analytic gradient without the additional coupled-perturbed Hartree-Fock step. Thus, the method can be useful for molecular dynamics simulations.

  17. The Competition of Charge Remote and Charge Directed Fragmentation Mechanisms in Quaternary Ammonium Salt Derivatized Peptides—An Isotopic Exchange Study

    NASA Astrophysics Data System (ADS)

    Cydzik, Marzena; Rudowska, Magdalena; Stefanowicz, Piotr; Szewczuk, Zbigniew

    2011-12-01

    Derivatization of peptides as quaternary ammonium salts (QAS) is a promising method for sensitive detection by electrospray ionization tandem mass spectrometry (Cydzik et al. J. Pept. Sci. 2011, 17, 445 -453). The peptides derivatized by QAS at their N-termini undergo fragmentation according to the two competing mechanisms - charge remote (ChR) and charge directed (ChD). The absence of mobile proton in the quaternary salt ion results in ChR dissociation of a peptide bond. However, Hofmann elimination of quaternary salt creates an ion with one mobile proton leading to the ChD fragmentation. The experiments on the quaternary ammonium salts with deuterated N-alkyl groups or amide NH bonds revealed that QAS derivatized peptides dissociate according to the mixed ChR-ChD mechanism. The isotopic labeling allows differentiation of fragments formed according to ChR and ChD mechanisms.

  18. Determination of {sup 16}O and {sup 18}O sensitivity factors and charge-exchange processes in low-energy ion scattering

    SciTech Connect

    Tellez, H.; Chater, R. J.; Fearn, S.; Symianakis, E.; Kilner, J. A.; Brongersma, H. H.

    2012-10-08

    Quantitative analysis in low-energy ion scattering (LEIS) requires an understanding of the charge-exchange processes to estimate the elemental sensitivity factors. In this work, the neutralization of He{sup +} scattered by {sup 18}O-exchanged silica at energies between 0.6 and 7 keV was studied. The process is dominated by Auger neutralization for E{sub i} < 0.8 keV. An additional mechanism starts above the reionization threshold. This collision-induced neutralization becomes the dominant mechanism for E{sub i} > 2 keV. The ion fractions P{sup +} were determined for Si and O using the characteristic velocity method to quantify the surface density. The {sup 18}O/{sup 16}O sensitivity ratio indicates an 18% higher sensitivity for the heavier O isotope.

  19. A comparison of empirical and experimental O7+, O8+, and O/H values, with applications to terrestrial solar wind charge exchange

    NASA Astrophysics Data System (ADS)

    Whittaker, Ian C.; Sembay, Steve

    2016-07-01

    Solar wind charge exchange occurs at Earth between the neutral planetary exosphere and highly charged ions of the solar wind. The main challenge in predicting the resultant photon flux in the X-ray energy bands is due to the interaction efficiency, known as the α value. This study produces experimental α values at the Earth, for oxygen emission in the range of 0.5-0.7 keV. Thirteen years of data from the Advanced Composition Explorer are examined, comparing O7+ and O8+ abundances, as well as O/H to other solar wind parameters allowing all parameters in the αO7,8+ calculation to be estimated based on solar wind velocity. Finally, a table is produced for a range of solar wind speeds giving average O7+ and O8+ abundances, O/H, and αO7,8+ values.

  20. Interaction of plasma jets produced from pinch plasma with neutral atoms in order to achieve an effective charge exchange table top X-laser

    SciTech Connect

    Engel, A.; Lebert, R.; Koshelev, K. N.; Sidelnikov, Yu. V.; Churilov, S. S.; Gavrilescu, C.; Neff, W.

    1997-05-05

    Charge exchange recombination is known as an effective scheme to get population inversion in the EUV-range. Highly ionised plasma jets and a neutral target could be very efficient ({sigma}{sub CE}>10{sup -15} cm{sup 2}) to realisation of this atomic scheme. Theoretical estimates and preliminary experiments show that for plasma focus with a stored energy of several kJ one can reach a substantial population inversion for ions of light elements with charge number Z<10. Experimental studies of production of these plasma jets in a 2 kJ plasma focus device is presented. Moreover the optimal properties of possible targets are investigated. Experimental results for the interaction of the plasma jets and targets are presented.

  1. DXL: A Sounding Rocket Mission for the Study of Solar Wind Charge Exchange and Local Hot Bubble X-Ray Emission

    NASA Technical Reports Server (NTRS)

    Galeazzi, M.; Prasai, K.; Uprety, Y.; Chiao, M.; Collier, M. R.; Koutroumpa, D.; Porter, F. S.; Snowden, S.; Cravens, T.; Robertson, I.; Kuntz, K. D.; Lepri, S.; McCammon, D.

    2011-01-01

    The Diffuse X-rays from the Local galaxy (DXL) mission is an approved sounding rocket project with a first launch scheduled around December 2012. Its goal is to identify and separate the X-ray emission generated by solar wind charge exchange from that of the local hot bubble to improve our understanding of both. With 1,000 square centimeters proportional counters and grasp of about 10 square centimeters sr both in the 1/4 and 3/4 keV bands, DXL will achieve in a 5-minute flight what cannot be achieved by current and future X-ray satellites.

  2. Heterodimers formed through a partial anionic exchange process: scanning tunneling spectroscopy to monitor bands across the junction vis-à-vis photoinduced charge separation

    NASA Astrophysics Data System (ADS)

    Bera, Abhijit; Saha, Sudip K.; Pal, Amlan J.

    2015-10-01

    We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk-heterojunction solar cells based on the nanostructures in a polymer matrix.We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk

  3. Solar Wind Charge Exchange X-ray emission from Mercury’s exosphere: Detectability with Bepi Colombo’s MIXS spectrometer

    NASA Astrophysics Data System (ADS)

    Koutroumpa, Dimitra; Dennerl, Konrad; Leblanc, François; Modolo, Ronan

    2015-11-01

    We have conducted preliminary hybrid simulations to calculate the Solar Wind Charge Exchange (SWCX) X-ray emission in Mercury’s exosphere. Our results imply that the OVII triplet emission intensity for standard slow solar wind conditions is of the same order as the one predicted by simulations for Mars and measured by Chandra in past observations of Mars. Using an oversimplified detector and observation geometry we explore the detectability of Mercury's SWCX emission by the MIXS spectrometer on board Bepi Colombo’s planetary orbiter (MPO).

  4. Measuring one-dimensional and two-dimensional impurity density profiles on TEXTOR using combined charge exchange-beam emission spectroscopy and ultrasoft x-ray tomography

    NASA Astrophysics Data System (ADS)

    De Bock, M.; Jakubowska, K.; Hellermann, M. von; Jaspers, R.; Donné, A. J. H.; Shmaenok, L.

    2004-10-01

    Two techniques are presented that allow us to measure impurity density profiles in the TEXTOR tokamak plasma. The one-dimensional profiles are gathered by charge exchange recombination spectroscopy (CXRS) in combination with beam emission spectroscopy (BES). Combining CXRS and BES eliminate the need for absolute calibration. For two-dimensional profiles an ultrasoft x-ray tomography system has been developed. The system is spectrally resolved and produces local emissivity profiles of several ionization stages of impurities. Both systems are presently being commissioned. They are complementary and give an insight into the impurity distribution and transport in plasmas.

  5. Measurement of Anomalously Strong Emission from the 1s-9p Transition in the Spectrum of H-like Phosphorus Following Charge Exchange with Molecular Hydrogen

    NASA Technical Reports Server (NTRS)

    Leutenegger, M. A.; Beiersdorfer, P.; Brown, G. V.; Kelley, R. L.; Porter, F. S.

    2010-01-01

    We have measured K-shell x-ray spectra of highly ionized argon and phosphorus following charge exchange with molecular hydrogen at low collision energy in an electron beam ion trap using an x-ray calorimeter array with approx.6 eV resolution. We find that the emission at the high-end of the Lyman series is greater by a factor of two for phosphorus than for argon, even though the measurement was performed concurrently and the atomic numbers are similar. This does not agree with current theoretical models and deviates from the trend observed in previous measurements.

  6. Hydrogen/Deuterium Exchange and Molecular Dynamics Analysis of Amyloid Fibrils Formed by a D69K Charge-Pair Mutant of Human Apolipoprotein C-II.

    PubMed

    Mao, Yu; Zlatic, Courtney O; Griffin, Michael D W; Howlett, Geoffrey J; Todorova, Nevena; Yarovsky, Irene; Gooley, Paul R

    2015-08-11

    Plasma apolipoproteins form amphipathic α helices in lipid environments but in the lipid-free state show a high propensity to form β structure and self-associate into amyloid fibrils. The widespread occurrence of apolipoproteins in amyloid plaques suggests disease-related roles, specifically in atherosclerosis. To reconcile the dual abilities of apolipoproteins to form either α helices or cross-β sheet structures, we examined fibrils formed by human apolipoprotein C-II (apoC-II). A structural model for apoC-II fibrils shows a cross-β core with parallel β strands, including a buried K30-D69 charge pair. We investigated the effect of abolishing this charge pair in mutant D69K apoC-II. Fluorescence studies indicated more rapid fibril formation and less solvent accessibility of tryptophan (W26) in D69K apoC-II fibrils than in wild-type (WT) fibrils. X-ray diffraction data of aligned D69K apoC-II fibrils yielded a typical cross-β structure with increased β sheet spacing compared to that of WT fibrils. Hydrogen/deuterium (H/D) exchange patterns were similar for D69K apoC-II fibrils compared to WT fibrils, albeit with an overall reduction in the level of slow H/D exchange, particularly around residues 29-32. Molecular dynamics simulations indicated reduced β strand content for a model D69K apoC-II tetramer compared to the WT tetramer and confirmed an expansion of the cross-β spacing that contributed to the formation of a stable charge pair between K69 and E27. The results highlight the importance of charge-pair interactions within the apoC-II fibril core, which together with numerous salt bridges in the flexible connecting loop play a major role in the ability of lipid-free apoC-II to form stable cross-β fibrils.

  7. Testing the color charge and mass dependence of parton energy loss with heavy-to-light ratios at BNL RHIC and CERN LHC

    SciTech Connect

    Armesto, Nestor; Dainese, Andrea; Salgado, Carlos A.; Wiedemann, Urs Achim

    2005-03-01

    The ratio of nuclear modification factors of high-p{sub T} heavy-flavored mesons to light-flavored hadrons ('heavy-to-light ratio') in nucleus-nucleus collisions tests the partonic mechanism expected to underlie jet quenching. Heavy-to-light ratios are mainly sensitive to the mass and color-charge dependences of medium-induced parton energy loss. Here, we assess the potential for identifying these two effects in D and B meson production at RHIC and at the LHC. To this end, we supplement the perturbative QCD factorized formalism for leading hadron production with radiative parton energy loss. For D meson spectra at high but experimentally accessible transverse momentum (10 < or approx. p{sub T} < or approx. 20 GeV) in Pb-Pb collisions at the LHC, we find that charm quarks behave essentially like light quarks. However, since light-flavored hadron yields are dominated by gluon parents, the heavy-to-light ratio of D mesons is a sensitive probe of the color-charge dependence of parton energy loss. In contrast, due to the larger b quark mass, the medium modification of B mesons in the same kinematical regime provides a sensitive test of the mass dependence of parton energy loss. At RHIC energies, the strategies for identifying and disentangling the color charge and mass dependence of parton energy loss are more involved because of the smaller kinematical range accessible. We argue that at RHIC, the kinematical regime best suited for such an analysis of D mesons is 7 < or approx. p{sub T} < or approx. 12 GeV, whereas the study of lower transverse momenta is further complicated due to the known dominant contribution of additional, particle species dependent, nonperturbative effects.

  8. Molecular orbital (SCF-X-α-SW) theory of Fe2+-Mn3+, Fe3+-Mn2+, and Fe3+-Mn3+ charge transfer and magnetic exchange in oxides and silicates

    USGS Publications Warehouse

    Sherman, David M.

    1990-01-01

    Metal-metal charge-transfer and magnetic exchange interactions have important effects on the optical spectra, crystal chemistry, and physics of minerals. Previous molecular orbital calculations have provided insight on the nature of Fe2+-Fe3+ and Fe2+-Ti4+ charge-transfer transitions in oxides and silicates. In this work, spin-unrestricted molecular orbital calculations on (FeMnO10) clusters are used to study the nature of magnetic exchange and electron delocalization (charge transfer) associated with Fe3+-Mn2+, Fe3+-Mn3+, and Fe2+-Mn3+ interactions in oxides and silicates. 

  9. Local pellet based and line-integrated nonperturbing charge exchange measurements with a compact neutral particle analyzer on Large Helical Device

    SciTech Connect

    Goncharov, P. R.; Ozaki, T.; Sudo, S.; Tamura, N.; Veshchev, E. A.; Sergeev, V. Yu.; Krasilnikov, A. V.

    2006-10-15

    Experiments on suprathermal ion physics are carried out on the Large Helical Device (LHD) with a 40 channel compact neutral particle analyzer (CNPA). The analyzer is used both in passive nonperturbing chord-integral neutral particle flux measurements and for local probing with an impurity pellet. The analyzer observes trapped particles with vertical bar v{sub parallel}/v vertical bar <0.25 and the pitch angle cosine value v{sub parallel}/v changes sign along the diagnostic sight line. The measurable energy range for H{sup 0} is 1-170 keV. Radially resolved data on local H{sup 0} atomic energy spectra have been obtained on LHD by the pellet charge exchange method with CNPA, as well as chord-integral atomic energy distribution data for electron cyclotron heated, neutral beam injected, and high power ion cyclotron heated plasma. The article addresses the diagnostic technical background and the analysis scheme of measurement results taking into account the helical geometry and the species and densities of the charge exchange targets.

  10. Radiochemical study of the medium energy pion double charge exchange reactions: /sup 209/Bi(pi/sup +/pi/sup -/)/sup 209-x/At

    SciTech Connect

    Clark, J.L.

    1980-01-01

    Carrier-free radiochemical techniques have been used to measure cross sections for the double charge exchange reactions of the type /sup 209/Bi(pi/sup +/, pi/sup -/xn)/sup 209-x/At for 100, 180, and 300 MeV incident pions. The observed formation of astatine products with mass numbers ranging from 208 to 205 is interpreted as evidence of processes in which energy deposited in the initial double charge exchange interaction is subsequently dissipated through neutron evaporation. The excitation functions for these reactions are seen to rise rapidly with decreasing incident pion energy with the maximum results for this study at 100 MeV. The astatine production cross secions measured for these positive pion irradiations of thick bismuth targets must be corrected for secondary processes, particularly the pion induced production of fast alpha particles which can contribute to the total cross sections through reactions like /sup 209/Bi(alpha,xn)/sup 213-x/At. The importance of these secondary contributions was studied through a series of negative pion irradiations of bismuth in which secondary pathways furnish the only means of producing astatine. The failure of evaporation calculations to reproduce the astatine product mass yields observed in these secondary studies suggests that direct mechanisms for energetic complex particle formation are quite important. Values for the alpha decay branches of /sup 207/At, /sup 208/At, and /sup 209/At were determined through a study of the electron capture and alpha decay characteristics of chemically purified astatine fractions.

  11. Water-molecule fragmentation induced by charge exchange in slow collisions with He{sup +} and He{sup 2+} ions in the keV-energy region

    SciTech Connect

    Cabrera-Trujillo, R.; Deumens, E.; Oehrn, Y.; Quinet, O.; Sabin, J. R.; Stolterfoht, N.

    2007-05-15

    Charge exchange and fragmentation in the collision systems He{sup 2+}+H{sub 2}O and He{sup +}+H{sub 2}O are theoretically investigated at projectile energies of a few keV. The calculations are based on the electron nuclear dynamics (END) method which solves the time-dependent Schroedinger equation. Total and differential cross sections for charge exchange are evaluated by averaging over 10 orientations of the H{sub 2}O molecule. Summed total electron capture cross sections are found to be in good agreement with available experimental data. Projectile scattering was studied in the full angular range with respect to the incident beam direction. The theory provides a description of the fragmentation mechanisms such as Coulomb explosion and binary collision processes. For impact parameters below 3.5 a.u., we find that single and double electron capture occurs, resulting always in full fragmentation of H{sub 2}O independent of the target orientation for {sup 3}He{sup 2+} ions. Hydrogen and oxygen fragments and its respective ions, are studied as a function of emission angle and energy. In the binary collisions regime the theoretical results are found to be in excellent agreement with previous experimental data. In the Coulomb explosion regime the theoretical data are found to peak at specific angles including 90 degree sign , which is consistent with the experiment.

  12. Water-molecule fragmentation induced by charge exchange in slow collisions with He+ and He2+ ions in the keV-energy region

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Deumens, E.; Öhrn, Y.; Quinet, O.; Sabin, J. R.; Stolterfoht, N.

    2007-05-01

    Charge exchange and fragmentation in the collision systems He2++H2O and He++H2O are theoretically investigated at projectile energies of a few keV. The calculations are based on the electron nuclear dynamics (END) method which solves the time-dependent Schrödinger equation. Total and differential cross sections for charge exchange are evaluated by averaging over 10 orientations of the H2O molecule. Summed total electron capture cross sections are found to be in good agreement with available experimental data. Projectile scattering was studied in the full angular range with respect to the incident beam direction. The theory provides a description of the fragmentation mechanisms such as Coulomb explosion and binary collision processes. For impact parameters below 3.5a.u. , we find that single and double electron capture occurs, resulting always in full fragmentation of H2O independent of the target orientation for He2+3 ions. Hydrogen and oxygen fragments and its respective ions, are studied as a function of emission angle and energy. In the binary collisions regime the theoretical results are found to be in excellent agreement with previous experimental data. In the Coulomb explosion regime the theoretical data are found to peak at specific angles including 90°, which is consistent with the experiment.

  13. EPR Line Shifts and Line Shape Changes Due to Spin Exchange of Nitroxide Free Radicals in Liquids 7. Singly-charged surfactant nitroxide

    PubMed Central

    Bales, Barney L; Harris, Francis L.; Peric, Mirna; Peric, Miroslav

    2009-01-01

    EPR spectra of aqueous solutions of the singly-charged surfactant nitroxide 4-[N,N-dimethyl-N-(n-dodecyl)ammonium]-2,2,6,6-tetramethylpiperidinyl-N-oxy bromide-d16 (DCAT12) are studied as functions of the molar concentration, c = 0.1 – 8 mM, and the temperature from 273 to 353 K. This concentration range is below the critical micelle concentration, cmc, at which DCAT12 forms micelles. Spin-spin broadening of the EPR lines averaged over the three lines is separated into contributions due to spin exchange, 〈Be〉, and dipolar, 〈Bdip〉, interactions yielding values of the fractional broadening by spin exchange, Ω(T), that vary from near unity at 353 K to approximately 50% at 273 K. This compares with a variation from unity to approximately 77% for a neutral spin probe perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (PDT) over the same range. Unlike PDT and the Stokes-Einstein prediction, the broadening constant by spin exchange, d 〈Be〉/dc, is not linear with T / η where η is the shear viscosity, instead following a quadratic dependence. Nevertheless, d 〈Be〉/dc is remarkable close to a hydrodynamic prediction using the Stokes-Einstein equation modified to take the spin probe charge into account. Compared with PDT, values of d 〈Be〉/dc are decreased and d 〈Bdip〉/dc increased at all temperatures, while the values of the re-encounter rate, τRE−1, deduced from line shifts, are reduced. Interestingly, values of d 〈Bdip〉/dc, Ω(T), and τRE−1 are comparable for PDT and DCAT12 when compared at the same rotational diffusion rates. PMID:19639954

  14. Exchange bias effect in Au-Fe3O4 dumbbell nanoparticles induced by the charge transfer from gold

    SciTech Connect

    Feygenson, Mikhail; Bauer, John C; Gai, Zheng; Marques, Carlos; Aronson, Meigan C.; Teng, Xiaowei; Su, Dong; Stanic, Vesna; Urban, Volker S; Kevin, Beyer; Dai, Sheng

    2015-08-10

    We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron scattering, synchrotron x-ray diffraction and scanning transmission electron microscope measurements determined the antiferromagnetic FeO wüstite phase within Fe3O4 nanoparticles, originating at the interface with the Au nanoparticles. The interface between antiferromagnetic FeO and ferrimagnetic Fe3O4 is giving rise to the exchange bias effect. The strength of the exchange bias fields depends on the interfacial area and lattice mismatch between both phases. We propose that the charge transfer from the Au nanoparticles is responsible for a partial reduction of the Fe3O4 into FeO phase at the interface with Au nanoparticles. The Au-O bonds are formed across the interface to accommodate an excess of oxygen released during the reduction of magnetite.

  15. Production of a high brightness H{sup -} beam by charge exchange of a hydrogen atom beam in a sodium jet

    SciTech Connect

    Davydenko, V.; Ivanov, A.; Kolmogorov, A.; Zelenski, A.

    2011-09-26

    Production of H{sup -} beams for applications in accelerators via charge exchange of a high brightness hydrogen neutral beam in a sodium jet cell is experimentally studied in a joint experiment by the Brookhaven National Laboratory (BNL) and the Budker Institute of Nuclear Physcis (BINP). In the experiment, a hydrogen atomic beam with an energy 3-6 keV, an equivalent current up to 5 A and a pulse duration 200 microseconds is used. Initial results demonstrate that an H{sup -} beam with a current 36 mA, an energy 5 keV and {approx}0.15 cm{center_dot}mrad normalized emittance was obtained. The recirculating sodium jet target with an entrance aperture 2 cm, which was developed for the BNL optically pumped polarized ion source, is used in the experiment. To increase the H{sup -} beam current, geometric focusing of the hydrogen neutral beam will be used in the future experiments. In addition, the effects of H{sup -} beam space-charge and sodium-jet stability will be studied to determine the basic limitations of this approach. The atomic beam is produced by charge exchange of a proton beam in a pulsed hydrogen target. The proton beam is formed by an ion source with a four-electrode multiaperture ion-optical system with small-size apertures. The plasma emission surface is formed by the plasma expansion from an arc plasma generator. The transverse ion temperature at the emission surface is 0.2 eV.

  16. Charge exchange in 3-30 keV H+ scattering off clean and AlF3 -covered Al(111) surfaces II. Theoretical study

    NASA Astrophysics Data System (ADS)

    Lugo, J. O.; Goldberg, E. C.; Sánchez, E. A.; Grizzi, O.

    2005-07-01

    The collision process of H+ with clean and AlF3 covered Al(111) surfaces is theoretically studied for large scattering angles and different ion incoming energies. The energy distributions of the charge fractions are analyzed as a function of the backscattered particle energy. Important differences between the two surfaces are found: in the case of pure Al the outgoing hydrogen particles are predominantly neutral, with a 10% of negative ions, while in the case of AlF3 an important positive charge fraction is observed. The theoretical calculation reproduces the experimental trends, and shows that these results are strongly related with the electronic structures in each case. In both surfaces a resonant mechanism is responsible for the charge exchange, but while in the pure Al case only the valence band states are involved, in the AlF3 case the promotion of the projectile energy level by the interaction with the core surface states inhibits the electron capture from the valence band.

  17. Loss of the AE3 Cl−/HCO−3 exchanger in mice affects rate-dependent inotropy and stress-related AKT signaling in heart

    PubMed Central

    Prasad, Vikram; Lorenz, John N.; Lasko, Valerie M.; Nieman, Michelle L.; Al Moamen, Nabeel J.; Shull, Gary E.

    2013-01-01

    Cl−/HCO−3 exchangers are expressed abundantly in cardiac muscle, suggesting that HCO−3 extrusion serves an important function in heart. Mice lacking Anion Exchanger Isoform 3 (AE3), a major cardiac Cl−/HCO−3 exchanger, appear healthy, but loss of AE3 causes decompensation in a hypertrophic cardiomyopathy (HCM) model. Using intra-ventricular pressure analysis, in vivo pacing, and molecular studies we identified physiological and biochemical changes caused by loss of AE3 that may contribute to decompensation in HCM. AE3-null mice had normal cardiac contractility under basal conditions and after β-adrenergic stimulation, but pacing of hearts revealed that frequency-dependent inotropy was blunted, suggesting that AE3-mediated HCO−3 extrusion is required for a robust force-frequency response (FFR) during acute biomechanical stress in vivo. Modest changes in expression of proteins that affect Ca2+-handling were observed, but Ca2+-transient analysis of AE3-null myocytes showed normal twitch-amplitude and Ca2+-clearance. Phosphorylation and expression of several proteins implicated in HCM and FFR, including phospholamban (PLN), myosin binding protein C, and troponin I were not altered in hearts of paced AE3-null mice; however, phosphorylation of Akt, which plays a central role in mechanosensory signaling, was significantly higher in paced AE3-null hearts than in wild-type controls and phosphorylation of AMPK, which is affected by Akt and is involved in energy metabolism and some cases of HCM, was reduced. These data show loss of AE3 leads to impaired rate-dependent inotropy, appears to affect mechanical stress-responsive signaling, and reduces activation of AMPK, which may contribute to decompensation in heart failure. PMID:24427143

  18. X-ray and EUV spectroscopy of various astrophysical and laboratory plasmas: Collisional, photoionization and charge-exchange plasmas

    SciTech Connect

    Liang, G. Y.; Li, F.; Wang, F. L.; Zhong, J. Y.; Zhao, G.; Wu, Y.

    2014-03-10

    Several laboratory facilities were used to benchmark theoretical spectral models that are extensively used by astronomical communities. However, there are still many differences between astrophysical environments and laboratory miniatures that can be archived. Here we setup a spectral analysis system for astrophysical and laboratory plasmas to make a bridge between them, and we investigate the effects from non-thermal electrons and the contributions from a metastable level population on level populations and charge stage distribution for coronal-like, photoionized, and geocoronal plasmas. Test applications to laboratory measurement (i.e., electron beam ion trap plasma) and astrophysical observation (i.e., Comet, Cygnus X-3) are presented. A time evolution of the charge stage and level population are also explored for collisional and photoionized plasmas.

  19. Collision induced dissociation of doubly-charged ions: Coulomb explosion vs. neutral loss in [Ca(urea)]{sup 2+} gas phase unimolecular reactivity via chemical dynamics simulations

    SciTech Connect

    Spezia, Riccardo; Salpin, Jean-Yves; Cimas, Alvaro; Gaigeot, Marie-Pierre; Song, Kihyung; Hase, William L.

    2012-07-01

    In this paper we report different theoretical approaches to study the gas-phase unimolecular dissociation of the doubly-charged cation [Ca(urea)]{sup 2+}, in order to rationalize recent experimental findings. Quantum mechanical plus molecular mechanical (QM/MM) direct chemical dynamics simulations were used to investigate collision induced dissociation (CID) and rotational-vibrational energy transfer for Ar{sup +} [Ca(urea)]{sup 2+} collisions. For the picosecond time-domain of the simulations, both neutral loss and Coulomb explosion reactions were found and the differences in their mechanisms elucidated. The loss of neutral urea subsequent to collision with Ar occurs via a shattering mechanism, while the formation of two singly-charged cations follows statistical (or almost statistical) dynamics. Vibrational-rotational energy transfer efficiencies obtained for trajectories that do not dissociate during the trajectory integration were used in conjunction with RRKM rate constants to approximate dissociation pathways assuming complete intramolecular vibrational energy redistribution (IVR) and statistical dynamics. This statistical limit predicts, as expected, that at long time the most stable species on the potential energy surface (PES) dominate. These results, coupled with experimental CID from which both neutral loss and Coulomb explosion products were obtained, show that the gas phase dissociation of this ion occurs by multiple mechanisms leading to different products and that reactivity on the complicated PES is dynamically complex. (authors)

  20. Loss rates of Europa's tenuous atmosphere

    NASA Astrophysics Data System (ADS)

    Lucchetti, Alice; Plainaki, Christina; Cremonese, Gabriele; Milillo, Anna; Cassidy, Timothy; Jia, Xianzhe; Shematovich, Valery

    2016-10-01

    Loss processes in Europa's tenuous atmosphere are dominated by plasma-neutral interactions. Based on the updated data of the plasma conditions in the vicinity of Europa (Bagenal et al. 2015), we provide estimations of the atmosphere loss rates for the H2O, O2 and H2 populations. Due to the high variability of the plasma proprieties, we perform our investigation for three sample plasma environment cases identified by Bagenal et al. as hot/low density, cold/high density, and an intermediate case. The role of charge-exchange interactions between atmospheric neutrals and three different plasma populations, i.e. magnetospheric, pickup, and ionospheric ions, is examined in detail. Our assumptions related to the pickup and to the ionospheric populations are based on the model by Sittler et al. (2013). We find that O2-O2+ charge-exchange is the fastest loss process for the most abundant atmospheric species O2, though this loss process has been neglected in previous atmospheric models. Using both the revised O2 column density obtained from the EGEON model (Plainaki et al., 2013) and the current loss rate estimates, we find that the upper limit for the volume integrated loss rate due to O2-O2+ charge exchange is in the range (13-51)×1026 s-1, depending on the moon's orbital phase and illumination conditions. The results of the current study are relevant to the investigation of Europa's interaction with Jupiter's magnetospheric plasma.

  1. Atomic charges of Cl- ions confined in a model Escherichia coli ClC-Cl-/H+ ion exchanger: a density functional theory study

    NASA Astrophysics Data System (ADS)

    Nieto-Delgado, P. G.; Arreola, J.; Guirado-López, R. A.

    2013-11-01

    We present extensive semi-empirical and pseudo-potential density functional theory calculations dedicated to analyse the stability, charge density distribution and migration behaviour of Cl- ions confined in model Escherichia coli (ec) ClC-Cl-/H+ ion-exchangers. Following recent high-resolution crystal structure determination in these kinds of systems, we use a finite-cluster model approach and construct various chemically simplified pore structures made of a glutamate residue -CH2-CH2-COO- (E148) and its closets 15, 19, 23 and 26 amino acids into which the Cl- ions will be confined. We reveal the sequence of molecular rearrangements induced on the E148 chain, which blocks the middle of the conduction pathway, leading to the pore opening. The -CH2-CH2-COO- fragment shows notable variations in its average charge density for small changes in the intra-cellular environment varying from -0.4e to -0.3e to -0.1e in the presence of zero, one and two confined Cl- ions, respectively, a result that reveals an interesting functionality of the E148 chain during Cl- conduction. We also obtain complex fluctuations in the ionic charge of the confined Cl- ions varying from ∼-0.7e to -0.2e, which deviate significantly from the value (-1e) usually used in classical simulations. By attaching a single H species to one of the oxygens of the glutamate group, we obtain that the -CH2-CH2-COOH fragment has now a small effective charge of ∼+0.25e. The energy barriers opposing the exit of the Cl- ions from our considered ion-exchangers vary from 0.65 eV to 4.7 eV, the smallest values being obtained for model structures exhibiting a high degree of flexibility and having protonated E148 fragments. Our results reinforce previous findings and provide additional physical insight, at the atomic level, on the gating process. Finally, we underline the importance of using electronically polarisable force fields to describe the transport of anionic species through this kind of molecular

  2. O₂(X³Σg⁻) and O₂(a¹Δg) charge exchange with simple ions.

    PubMed

    Ziółkowski, Marcin; Schatz, George C; Viggiano, A A; Midey, Anthony; Dotan, Itzhak

    2014-06-01

    We present theory and experiments which describe charge transfer from the X³Σg⁻ and a(1)Δg states of molecular oxygen and atomic and molecular cations. Included in this work are new experimental results for O2(a(1)Δg) and the cations O(+), CO(+), Ar(+), and N₂⁺, and new theory based on complete active space self-consistent field method calculations and an extended Langevin model to calculate rate constants for ground and excited O2 reacting with the atomic ions Ar(+), Kr(+), Xe(+), Cl(+), and Br(+). The T-shaped orientation of the (X - O2)(+) potential surface is used for the calculations, including all the low lying states up to the second singlet state of the oxygen molecule b¹Σ(g)⁺. The calculated rate constants for both O₂(X³Σg⁻) and O2(a(1)Δg) show consistent trends with the experimental results, with a significant dependence of rate constant on charge transfer exothermicity that does not depend strongly on the nature of the cation. The comparisons with theory show that partners with exothermicities of about 1 eV have stronger interactions with O2, leading to larger Langevin radii, and also that more of the electronic states are attractive rather than repulsive, leading to larger rate constants. Rate constants for charge transfer involving O2(a(1)Δg) are similar to those for O₂(X³Σg⁻) for a given exothermicity ignoring the electronic excitation of the O2(a(1)Δg) state. This means (and the electronic structure calculations support) that the ground and excited states of O2 have about the same attractive interactions with ions.

  3. NUMEN Project @ LNS : Heavy Ions Double Charge Exchange as a tool towards the 0νββ Nuclear Matrix Element

    NASA Astrophysics Data System (ADS)

    Agodi, C.; Cappuzzello, F.; Bonanno, D. L.; Bongiovanni, D. G.; Branchina, V.; Calabrese, S.; Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Foti, A.; Finocchiaro, P.; Greco, V.; Lanzalone, G.; Lo Presti, D.; Longhitano, F.; Muoio, A.; Pandola, L.; Rifuggiato, D.; Tudisco, S.

    2016-06-01

    The NUMEN Project, proposed at INFN Laboratori Nazionali del Sud (LNS) in Catania, has the aim to access the nuclear matrix elements, entering the expression of the life time of double beta decay, by relevant cross sections of double charge exchange reactions. The basic point, on which it is based this innovative technique, is the coincidence of the initial and final state wave-functions in the two classes of processes and the similarity of the transition operators. A key aspect of the Project is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN LNS K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  4. Expressions for Form Factors for Inelastic Scattering and Charge Exchange in Plane-Wave, Distorted-Wave, and Coupled-Channels Reaction Formalisms

    SciTech Connect

    Dietrich, F S

    2006-09-25

    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 calculations. The Fourier transform methods used to calculate the plane-wave approximation cross sections are also intended to be used to generate the transition potentials for coupled-channels codes, using a folding model with local effective interactions. Specific expressions are given for calculating transition densities for the folding model in the random phase approximation (RPA).

  5. Measurement of deuterium density profiles in the H-mode steep gradient region using charge exchange recombination spectroscopy on DIII-D

    NASA Astrophysics Data System (ADS)

    Haskey, S. R.; Grierson, B. A.; Burrell, K. H.; Chrystal, C.; Groebner, R. J.; Kaplan, D. H.; Pablant, N. A.; Stagner, L.

    2016-11-01

    Recent completion of a thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. In a H-mode DIII-D discharge, these new measurement capabilities are used to provide the deuterium density profile, demonstrate the importance of profile alignment between Thomson scattering and CER diagnostics, and aid in determining the electron temperature at the separatrix. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the plasma edge, providing high resolution measurements across the pedestal and steep gradient region in H-mode plasmas. Extracting useful physical quantities such as deuterium density is challenging due to multiple photoemission processes. These challenges are overcome using a detailed fitting model and by forward modeling the photoemission using the FIDASIM code, which implements a comprehensive collisional radiative model.

  6. Visible and near UV photon spectroscopy of charge-exchange collisions between Ar7+ and Li at 105 keV

    NASA Astrophysics Data System (ADS)

    Jacquet, E.; Boduch, P.; Chantepie, M.; Druetta, M.; Hennecart, D.; Husson, X.; Lecler, D.; Wilson, M.

    1994-04-01

    Charge exchange collisions at 105 keV between Ar7+ ions and lithium atoms have been studied by photon spectroscopy in the 2000-6000 Å wavelength range. A large number of new lines in Ar VII have been identified with the help of ab initio pseudo-relativistic Hartree-Fock calculations taking into account electrostatic interactions between 3snl (n = 6-10), 3 pnl (n = 4-6) and 3dnl (n = 4) configurations. They correspond to transitions 3snl-3sn'l' with n = 7, 8, 9 and Δn = 1 and 2. Lines in Ar VI were also observed and identified as transitions 3s2nl-3s2n'l' and 3s3pnl-3s3pn'l'(n = 6, 7) and Δn = 1.

  7. Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

    NASA Astrophysics Data System (ADS)

    Wu, Jing; Yao, Lieming; Zhu, Jianhua; Han, Xiaoyu; Li, Wenzhu

    2012-11-01

    This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum (CXRS) diagnostics tool built on the HL-2A tokamak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutral beam injection (NBI) heating. Considering the edge effect of the line of CVI 529.06 nm (n = 8~7), which contains three lines (active exciting spectral line (ACX), passivity exciting spectral line (PCX) and electron exciting spectral line (ICE)), and using three Gaussian fitted curves, we obtain the following experimental results: the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m · s-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.

  8. Positive-pion double-charge-exchange reaction: experiments on the isotopic pairs oxygen-16,18 and magnesium-24,26

    SciTech Connect

    Greene, S.J.

    1981-06-01

    The (..pi../sup +/,..pi../sup -/) double-charge-exchange (DCX) reaction has been performed on targets of T = 0,1 isospin (and isotopic) pairs /sup 16/ /sup 18/O and /sup 24/ /sup 26/Mg. Energy excitation functions of d sigma/d ..cap omega.., across the (3,3) ..pi..-N resonance, are presented for transitions to double-isobaric analog state (DIAS) and non-DIAS ground-state residual nuclei. Angular distributions in the region of 5/sup 0/ to 33/sup 0/ are presented for the DIAS from the T = 1 nuclei. The similarities and differences of DIAS and non-DIAS distributions are discussed in relation to reaction-mechanism and nuclear-structure effects. Also, a simple, two-amplitude model for the /sup 18/O excitation function, consistent with the data, is presented. The utility of DCX in nuclear mass measurements is discussed, with some examples.

  9. Quantum-size effects in the energy loss of charged particles interacting with a confined two-dimensional electron gas

    SciTech Connect

    Borisov, A. G.; Juaristi, J. I.

    2006-01-15

    Time-dependent density-functional theory is used to calculate quantum-size effects in the energy loss of antiprotons interacting with a confined two-dimensional electron gas. The antiprotons follow a trajectory normal to jellium circular clusters of variable size, crossing every cluster at its geometrical center. Analysis of the characteristic time scales that define the process is made. For high-enough velocities, the interaction time between the projectile and the target electrons is shorter than the time needed for the density excitation to travel along the cluster. The finite-size object then behaves as an infinite system, and no quantum-size effects appear in the energy loss. For small velocities, the discretization of levels in the cluster plays a role and the energy loss does depend on the system size. A comparison to results obtained using linear theory of screening is made, and the relative contributions of electron-hole pair and plasmon excitations to the total energy loss are analyzed. This comparison also allows us to show the importance of a nonlinear treatment of the screening in the interaction process.

  10. Effect of resin charged functional group, porosity, and chemical matrix on the long-term pharmaceutical removal mechanism by conventional ion exchange resins.

    PubMed

    Wang, Wei; Li, Xiaofeng; Yuan, Shengliu; Sun, Jian; Zheng, Shaokui

    2016-10-01

    This study attempted to clarify the long-term pharmaceutical removal mechanism from sewage treatment plant effluent during the cyclical adsorption-regeneration operation of 5 commercial resin-based fixed-bed reactors with the simultaneous occurrence of electrostatic interactions and complex non-electrostatic interactions. It examined 12 pharmaceuticals belonging to 10 therapeutic classes with different predominant existing forms and hydrophobicities. Furthermore, the effect of the resin charged functional group (strong-base vs. strong-acid vs. non-ionic), porosity (macroporous vs. gel), and chemical matrix (polystyrenic vs. polyacrylic) on the mechanism was investigated to optimize resin properties and achieve higher pharmaceutical removal. The results reported herein indicate the importance of non-electrostatic interactions between pharmaceuticals and the resin backbone during short-term cyclical operation (i.e., the 1st adsorption-regeneration cycle). With the development of cyclical operation, however, non-electrostatic interaction-induced pharmaceutical removal generally decreased and even disappeared when equilibrium was achieved between the influent and the resin. Despite pharmaceutical therapeutic class or hydrophilicity, anion (or cation) exchange resin preferentially removed those pharmaceuticals that were predominantly present as organic anions (or cations) by ion exchange process during long-term cyclical operation (i.e., ≥6 adsorption-regeneration cycles). Besides pharmaceuticals predominantly present as undissociated molecules, some amphoteric pharmaceuticals containing large amounts of zwitterions were also difficult to remove by ion exchange resin. Additionally, neither resin porosity nor chemical matrix had any significant effect on the long-term pharmaceutical removal mechanism.

  11. Effect of resin charged functional group, porosity, and chemical matrix on the long-term pharmaceutical removal mechanism by conventional ion exchange resins.

    PubMed

    Wang, Wei; Li, Xiaofeng; Yuan, Shengliu; Sun, Jian; Zheng, Shaokui

    2016-10-01

    This study attempted to clarify the long-term pharmaceutical removal mechanism from sewage treatment plant effluent during the cyclical adsorption-regeneration operation of 5 commercial resin-based fixed-bed reactors with the simultaneous occurrence of electrostatic interactions and complex non-electrostatic interactions. It examined 12 pharmaceuticals belonging to 10 therapeutic classes with different predominant existing forms and hydrophobicities. Furthermore, the effect of the resin charged functional group (strong-base vs. strong-acid vs. non-ionic), porosity (macroporous vs. gel), and chemical matrix (polystyrenic vs. polyacrylic) on the mechanism was investigated to optimize resin properties and achieve higher pharmaceutical removal. The results reported herein indicate the importance of non-electrostatic interactions between pharmaceuticals and the resin backbone during short-term cyclical operation (i.e., the 1st adsorption-regeneration cycle). With the development of cyclical operation, however, non-electrostatic interaction-induced pharmaceutical removal generally decreased and even disappeared when equilibrium was achieved between the influent and the resin. Despite pharmaceutical therapeutic class or hydrophilicity, anion (or cation) exchange resin preferentially removed those pharmaceuticals that were predominantly present as organic anions (or cations) by ion exchange process during long-term cyclical operation (i.e., ≥6 adsorption-regeneration cycles). Besides pharmaceuticals predominantly present as undissociated molecules, some amphoteric pharmaceuticals containing large amounts of zwitterions were also difficult to remove by ion exchange resin. Additionally, neither resin porosity nor chemical matrix had any significant effect on the long-term pharmaceutical removal mechanism. PMID:27367175

  12. Rapid analysis of charge variants of monoclonal antibodies using non-linear salt gradient in cation-exchange high performance liquid chromatography.

    PubMed

    Joshi, Varsha; Kumar, Vijesh; Rathore, Anurag S

    2015-08-01

    A method is proposed for rapid development of a short, analytical cation exchange high performance liquid chromatography method for analysis of charge heterogeneity in monoclonal antibody products. The parameters investigated and optimized include pH, shape of elution gradient and length of the column. It is found that the most important parameter for development of a shorter method is the choice of the shape of elution gradient. In this paper, we propose a step by step approach to develop a non-linear sigmoidal shape gradient for analysis of charge heterogeneity for two different monoclonal antibody products. The use of this gradient not only decreases the run time of the method to 4min against the conventional method that takes more than 40min but also the resolution is retained. Superiority of the phosphate gradient over sodium chloride gradient for elution of mAbs is also observed. The method has been successfully evaluated for specificity, sensitivity, linearity, limit of detection, and limit of quantification. Application of this method as a potential at-line process analytical technology tool has been suggested.

  13. Controlling hydrogen scrambling in multiply charged protein ions during collisional activation: implications for top-down hydrogen/deuterium exchange MS utilizing collisional activation in the gas phase.

    PubMed

    Abzalimov, Rinat R; Kaltashov, Igor A

    2010-02-01

    Hydrogen exchange in solution combined with ion fragmentation in the gas phase followed by MS detection emerged in recent years as a powerful tool to study higher order protein structure and dynamics. However, a certain type of ion chemistry in the gas phase, namely, internal rearrangement of labile hydrogen atoms (the so-called hydrogen scrambling), is often cited as a factor limiting the utility of this experimental technique. Although several studies have been carried out to elucidate the roles played by various factors in the occurrence and the extent of hydrogen scrambling, there is still no consensus as to what experimental protocol should be followed to avoid or minimize it. In this study we employ fragmentation of mass-selected subpopulations of protein ions to assess the extent of internal proton mobility prior to dissociation. A unique advantage of tandem MS is that it not only provides a means to map the deuterium content of protein ions whose overall levels of isotope incorporation can be precisely defined by controlling the mass selection window, but also correlates this spatial isotope distribution with such global characteristic as the protein ion charge state. Hydrogen scrambling does not occur when the charge state of the precursor protein ions selected for fragmentation is high. Fragment ions derived from both N- and C-terminal parts of the protein are equally unaffected by scrambling. However, spatial distribution of deuterium atoms obtained by fragmenting low-charge-density protein ions is consistent with a very high degree of scrambling prior to the dissociation events. The extent of hydrogen scrambling is also high when multistage fragmentation is used to probe deuterium incorporation locally. Taken together, the experimental results provide a coherent picture of intramolecular processes occurring prior to the dissociation event and provide guidance for the design of experiments whose outcome is unaffected by hydrogen scrambling.

  14. A new method for charge-loss correction of room-temperature semiconductor detectors using digital trapezoidal pulse shaping

    NASA Astrophysics Data System (ADS)

    Nakhostin, M.; Veeramani, P.

    2012-06-01

    It is well known that semiconductor detectors operating at room temperature can be read out at high rate, with good noise performance and low sensitivity to ballistic deficit, by using trapezoidal (flat-topped) pulse shaping. Nevertheless, the energy resolution of these detectors is also affected by chargetrapping inside the detector crystal, which can not be compensated by the standard trapezoidal pulse shaping. A new digital algorithm based on trapezoidal pulse shaping, to compensate for the charge-trapping effect while minimizing the electronic noise, has been developed. The application of the pulse processing algorithm to a 5 × 5 × 1 mm3 planar Schottky CdTe detector leads to an energy resolution of 1.15% FWHM at 662 keV at room temperature, which is considerably superior to the results of the standard pulse filters.

  15. Measurements of asymmetries of pion single charge exchange on polarized 3He at 200 MeV

    NASA Astrophysics Data System (ADS)

    Zhao, Q.; Burleson, G.; Blanchard, S.; Chang, T.; Gibbs, W.; Haas, J.; Park, B.; Whitton, M.; Espy, M.; Dehnhard, D.; Larson, B.; O'donnell, J.; Palarczyk, M.; Cummings, W.; Delheij, P.; Häusser, O.; Pasyuk, E.; Gostkin, M.; Amann, J.; Boudrie, R.; Riedel, C.; Morris, C.; Pentillä, S.; Swenson, D.; Tupa, D.; Comfort, J.; Gaulard, C.; Maeda, K.; Glass, G.; Supek, I.

    1999-08-01

    Asymmetries for the (π-,π0) reaction on polarized 3He were measured using a 200-MeV pion beam at LAMPF. The π0's were detected with the neutral meson spectrometer in coincidence with the recoiling tritons. A recoil triton detector, consisting of scintillation-counter telescopes and a wire chamber, was used to measure the time-of-flight, energy loss, and direction of the tritons. The polarized gaseous 3He target, developed at TRIUMF, was modified to run with two diode lasers; the polarization reached 65%. The asymmetries between θlab=60° and 105° were found to be strongly angle dependent. The results are compared with theoretical calculations.

  16. Search for metastable heavy charged particles with large ionization energy loss in p p collisions at √{s }=13 TeV using the ATLAS experiment

    NASA Astrophysics Data System (ADS)

    Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Aben, R.; Abouzeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agricola, J.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonelli, M.; Antonov, A.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethke, S.; Bevan, A. J.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Biedermann, D.; Bielski, R.; Biesuz, N. V.; Biglietti, M.; Bilbao de Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biondi, S.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blanco, J. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogaerts, J. A.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Brunt, Bh; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Caloba, L. P.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Canepa, A.; Cano Bret, M.; Cantero, J.; Cantrill, R.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carminati, L.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castaneda-Miranda, E.; Castelijn, R.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerda Alberich, L.; Cerio, B. C.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chatterjee, A.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Chow, B. K. 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A.; Viel, S.; Vigani, L.; Vigne, R.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, W.; Wang, X.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wollstadt, S. J.; Wolter, M. W.; Wolters, H.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yakabe, R.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yen, A. L.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zengel, K.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zur Nedden, M.; Zurzolo, G.; Zwalinski, L.; Atlas Collaboration

    2016-06-01

    This paper presents a search for massive charged long-lived particles produced in p p collisions at √{s }=13 TeV at the LHC using the ATLAS experiment. The data set used corresponds to an integrated luminosity of 3.2 fb-1. Many extensions of the Standard Model predict the existence of massive charged long-lived particles, such as R -hadrons. These massive particles are expected to be produced with a velocity significantly below the speed of light, and therefore to have a specific ionization higher than any Standard Model particle of unit charge at high momenta. The Pixel subsystem of the ATLAS detector is used to measure the ionization energy loss of reconstructed charged particles and to search for such highly ionizing particles. The search presented here has much greater sensitivity than a similar search performed using the ATLAS detector in the √{s }=8 TeV data set, thanks to the increase in expected signal cross section due to the higher center-of-mass energy of collisions, to an upgraded detector with a new silicon layer close to the interaction point, and to analysis improvements. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on R -hadron production cross sections and masses are set. Gluino R -hadrons with lifetimes above 0.4 ns and decaying to q q ¯ plus a 100 GeV neutralino are excluded at the 95% confidence level, with lower mass limit ranging between 740 and 1590 GeV. In the case of stable R -hadrons the lower mass limit at the 95% confidence level is 1570 GeV.

  17. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-12-01

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  18. XMM-Newton Observations of MBM 12: More Constraints on the Solar Wind Charge Exchange and Local Bubble Emissions

    NASA Technical Reports Server (NTRS)

    Koutroumpa, Dimitra; Smith, Randall K.; Edgar, Richard J.; Kuntz, Kip D.; Plucinsky, Paul P.; Snowden, Steven L.

    2010-01-01

    We present the first analysis of an XMM-Newton observation of the nearby molecular cloud MBM 12. We find that in the direction of MBM 12 the total O VII (0.57 keV) triplet emission is 1.8(+0.5/-0.6) photons/sq cm/s/sr (or Line Units - LU) while for the O VIII (0.65 keV) line emission we find a 3(sigma) upper limit of <1 LU. We also use a heliospheric model to calculate the O VII and O VIII emission generated by Solar Wind Charge-eXchange (SWCX) which we compare to the XMM-Newton observations. This comparison provides new constraints on the relative heliospheric and Local Bubble contributions to the local diffuse X-ray background. The heliospheric SWCX model predicts 0.82 LU for O VII, which accounts for approx. 46+/-15% of the observed value, and 0.33 LU for the O VIII line emission consistent with the XMM-Newton observed value. We discuss our results in combination with previous observations of the MBM 12 with CHANDRA and Suzaku.

  19. XMM-NEWTON OBSERVATIONS OF MBM 12: MORE CONSTRAINTS ON THE SOLAR WIND CHARGE EXCHANGE AND LOCAL BUBBLE EMISSIONS

    SciTech Connect

    Koutroumpa, Dimitra; Snowden, Steven L.; Kuntz, Kip D.

    2011-01-10

    We present the first analysis of an XMM-Newton observation of the nearby molecular cloud MBM 12. We find that in the direction of MBM 12 the total O VII (0.57 keV) triplet emission is 1.8{sup +0.5}{sub -0.6} photons cm{sup -2} s{sup -1} sr{sup -1} (or line units, LU) while for the O VIII (0.65 keV) line emission we find a 3{sigma} upper limit of <1 LU. We use a heliospheric model to calculate the O VII and O VIII emission generated by Solar Wind Charge-eXchange (SWCX) which we compare to the XMM-Newton observations. This comparison provides new constraints on the relative heliospheric and Local Bubble contributions to the local diffuse X-ray background. The heliospheric SWCX model predicts 0.82 LU for O VII, which accounts for {approx}46% {+-} 15% of the observed value, and 0.33 LU for the O VIII line emission consistent with the XMM-Newton observed value. We discuss our results in combination with previous observations of MBM 12 with Chandra and Suzaku.

  20. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    SciTech Connect

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-12-15

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  1. Neutron Time-of-Flight Measurements of Charged-Particle Energy Loss in Inertial Confinement Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Sayre, Daniel; Cerjan, Charlie; Berzak Hopkins, Laura; Caggiano, Joseph; Divol, Laurent; Eckart, Mark; Graziani, Frank; Grim, Gary; Hartouni, Ed; Hatarik, Robert; Le Pape, Sebastien; MacKinnon, Andrew; Schneider, Dieter; Sepke, Scott

    2015-11-01

    Neutron time-of-flight measurements of inflight T (d , n) α reactions created during an implosion of a deuterium gas target have been performed at the National Ignition Facility, with order of magnitude improvements in statistics and resolution over past experiments. In the implosion, energetic tritons emitted by thermonuclear fusion within the deuterium plasma produced over 1011 inflight T (d , n) α reactions. The yield and particle spectrum of inflight reactions are sensitive to the triton's energy loss in the plasma, which, in this implosion, consisted of multi-keV temperatures and number densities above 1024 cm-3. Radiation-hydrodynamic simulations of the implosion were adjusted to match the yield and broadening of the D (d , n) 3 He neutron peak. These same simulations give reasonable agreement with the measured T (d , n) α yield and neutron spectrum, and this provides a strong consistency check of the simulated plasma conditions and energy loss model. This research was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  2. Study on the mechanism of a charge-coupled device detector irradiated by millisecond pulse laser under functional loss.

    PubMed

    Li, Mingxin; Jin, Guangyong; Tan, Yong; Guo, Ming; Zhu, Pengbo

    2016-02-20

    The damage mechanism of a CCD detector was studied by building an experimental system containing a millisecond pulse laser irradiating a CCD detector. The experimental results show that the damage on the CCD detector was mainly thermal damage, along with mechanical damage. A melting phenomenon was caused by the thermal damage, so that a crater was observed on the surface of the CCD detector. Caused by melting of the polysilicon electrodes and a temperature rise in the silicon dioxide, the shift register impedance values were sharply reduced. Most of the substrate clock signals were broken and disappeared due to melting of channels in the silicon substrate layer, which caused a functional loss for the CCD detector. The mechanical damage on the melting edge of the CCD detector created heave; the temperature gradient caused this damage. In this paper, the decrease in vertical shift register impedance values was consistent with previous test results. PMID:26906576

  3. Joy of cex: Sharpening the (t,He-3) probe at 345 MeV for the charge-exchange knife drawer

    NASA Astrophysics Data System (ADS)

    Howard, Meredith E.

    This data set represents the first step in a campaign of (t, 3He) charge-exchange experiments at the National Superconducting Cyclotron Laboratory designed explicitly to measure Gamow-Teller strength distributions in the electron capture direction for stable medium-heavy atomic nuclei, with particular interest in reaching the nuclei in the pf -shell or masses up to A=112. The 115 MeV/nucleon secondary triton beam with an average intensity of 4x106 pps on 10 mg/cm2 thick target foils produces 3He that are measured in the focal plane detectors of the S800 magnetic spectrometer. From these data, the scattering angle of the tritons is reconstructed to within 7 mrad and the energy of the recoil nucleus is reconstructed to better then 250 keV. Since there is no comprehensive study of the (t, 3He) probe for triton energies of 100-400 MeV/nucleon, this data is the first step in evaluating the advantages of extracting B(GT) from the (t,3He) probe over other hadronic probes. The first target is a CD2 target used for calibrating cross section. This is the third measurement for the (t, 3He) probe on 12C above 100 MeV/nucleon. The present 12C(t,3He) cross section for the 12B ground state (Jpi = 1 +) is lower than a previous measurement at the NSCL by more than one standard deviation in uncertainty but agrees with 12C( 3He,t)12N. This (t,3He) measurement for 24Mg, the second target, is the first above 100 MeV/nucleon. The B(GT) distribution for 24Na is extracted from differential cross sections as a function of residual nucleus excitation energy up to 7 MeV. For each peak in excitation energy, the differential cross section as a function of reconstructed scattering angle is extrapolated to zero degrees using angular distrubutions calculated with the distorted wave calculations from the code FOLD and transformed to q = 0 zero momentum transfer. Uncertainties in the B(GT) include a calculation of interference to Jpi=1 + expected from DeltaL=2, DeltaS=1 reactions. Comparisons of B

  4. Chronic alcohol consumption augments loss of sialic acid residues and alters erythrocyte membrane charge in type II diabetic patients.

    PubMed

    Degirmenci, Serkan; Akalin, Aysen; Kartkaya, Kazim; Kanbak, Güngör

    2008-01-01

    In this study, the effects of alcohol consumption on erythrocyte membrane properties in type 2 diabetic patients were investigated. Therefore, we measured total and lipid-bound sialic acid (LSA) levels, sialidase activities, and erythrocyte membrane negative charge. Three groups, including control group (n = 20), alcohol-consuming diabetic patients group (n = 14), and diabetic patients without alcohol consumption group (n = 42), were created. Plasma total sialic acid (TSA) levels of the alcohol-consuming diabetic group were elevated as compared to the healthy control and diabetic group (p < 0.001 and p < 0.01, respectively). TSA levels of the diabetic group were significantly elevated as compared to the healthy control group (p > 0.001). Plasma LSA levels of the alcohol-consuming diabetic group were higher than that in the healthy control and diabetic group (p < 0.05 and p < 0.05, respectively). LSA levels of the diabetic group were found to be high as compared to the healthy control group (p < 0.05). Plasma sialidase activities of the alcohol-consuming diabetic group and diabetic group were significantly elevated as compared to the healthy control group (p < 0.05 and p < 0.05, respectively). Sialidase activities of the alcohol-consuming diabetic group were elevated as compared to the diabetic group, but this was not statistically significant (p > 0.05). Erythrocyte membrane negativity levels of the alcohol-consuming diabetic group and diabetic group were significantly decreased (p < 0.001 and p < 0.001, respectively) as compared to the healthy control group. Erythrocyte membrane negativity levels of the alcohol-consuming diabetic group were decreased as compared to the diabetic group, but this was not statistically significant (p > 0.05). In conclusion, our results indicate that chronic alcohol consumption may augment membrane alterations in type 2 diabetic patients.

  5. Measurement of radial profiles of density ratio of helium to hydrogen ion using charge exchange spectroscopy with two-wavelength spectrometer.

    PubMed

    Ida, K; Yoshinuma, M; Wieland, B; Goto, M; Nakamura, Y; Kobayashi, M; Murakami, I; Moon, C

    2015-12-01

    Radial profiles of density ratio of helium to hydrogen ions are measured using the charge exchange spectroscopy technique with the two-wavelength spectrometer system in the large helical device. The two-wavelength spectrometer system consists of a dichroic mirror box, a spectrometer with two grating and two camera lenses, and one CCD detector. The dichroic mirror box is used to divide the light of one fiber from the plasma to two fibers, one for HeII (λ = 468.6 nm) and the other for H(α) (λ = 656.3 nm), that are connected to the entrance slit of the spectrometer to eliminate the interference between the HeII and the H(α) spectra on the CCD. This system provides a simultaneous measurement of helium and hydrogen ion density ratio at 8 exact same locations (8 spatial channels) with a time resolution of >40 ms in the wide range of the density ratio of 0.05-5.

  6. A diagnostic neutral beam system for the MST reversed-field pinch: Charge-exchange recombination spectroscopy and Rutherford scattering (abstract)

    NASA Astrophysics Data System (ADS)

    Den Hartog, D. J.; Fiksel, G.; Davydenko, V.; Ivanov, A.; Mishagin, V.

    1999-01-01

    A diagnostic neutral beam system is being purchased for the MST reversed-field pinch. Initially, this beam will be used for charge-exchange recombination spectroscopy (CHERS) to measure impurity ion velocity and temperature, both equilibrium and fluctuating. This work is an extension of an existing MST spectroscopic diagnostic which has successfully measured chord-averaged flow with 10 μs time resolution [D. J. Den Hartog and R. J. Fonck, Rev. Sci. Instrum. 65, 3238 (1994)]. CHERS will provide high spatial resolution, critically needed for the investigation of fluctuations associated with the dynamo and transport. This beam will also be applied to Rutherford scattering for local measurements of majority ion velocity and temperature. Ion velocity is determined by the shift of the energy spectrum of the scattered neutral beam; ion temperature by the width of the energy spectrum. The scattered spectrum will be detected by two multichannel neutral particle analyzers. In order to achieve a time resolution of about 10 μs, the neutral beam equivalent current density and current must be high; both of these characteristics are hallmarks of the DINA beam design.

  7. Charge exchange in Be4+-H(n = 1, 2) collisions studied systematically by atomic-orbital close-coupling calculations

    NASA Astrophysics Data System (ADS)

    Igenbergs, K.; Schweinzer, J.; Aumayr, F.

    2009-12-01

    Charge exchange in Be4+-H(n = 1, 2) collisions was studied using the atomic-orbital close-coupling formalism in its impact parameter description and applying electron translational factors. Calculations were carried out in the energy range of 1-750 keV amu-1 with fully stripped beryllium ions impacting on atomic hydrogen in its ground state (1s) and in the excited n = 2 states. An optimized description of both collision centres was determined by analysing the convergence of the total cross sections and also by comparison with other theoretical approaches. This optimized description consists of up to 170 basis states involving hydrogen-like states and pseudostates. We present total, n-resolved as well as nell-resolved cross sections. The latter are needed to evaluate the emission cross sections in two limiting collisional plasma environments, i.e. single-collisional and multi-collisional. The calculated emission cross sections are compared with experimental data from the fusion experiment JET. Taking the experimental environment and certain characteristics of the theoretical methods into account, the agreement can be considered to be quite good.

  8. On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.; Holmstrom, M.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, T. J.; Travnicek, P.; Walsh, B. M.

    2014-01-01

    We analyze the Rontgen satellite (ROSAT) position sensitive proportional counter soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges: two 19 deg wedges (one north and one south) 13-32 deg off the terminator toward the dark side and one wedge 38 deg wide centered on the antisolar direction. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 deg wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now, along with Mars, Venus, and Earth, the Moon represents another solar system body at which SWCX has been observed.

  9. Loss of Slc4a1b chloride/bicarbonate exchanger function protects mechanosensory hair cells from aminoglycoside damage in the zebrafish mutant persephone.

    PubMed

    Hailey, Dale W; Roberts, Brock; Owens, Kelly N; Stewart, Andrew K; Linbo, Tor; Pujol, Remy; Alper, Seth L; Rubel, Edwin W; Raible, David W

    2012-01-01

    Mechanosensory hair cell death is a leading cause of hearing and balance disorders in the human population. Hair cells are remarkably sensitive to environmental insults such as excessive noise and exposure to some otherwise therapeutic drugs. However, individual responses to damaging agents can vary, in part due to genetic differences. We previously carried out a forward genetic screen using the zebrafish lateral line system to identify mutations that alter the response of larval hair cells to the antibiotic neomycin, one of a class of aminoglycoside compounds that cause hair cell death in humans. The persephone mutation confers resistance to aminoglycosides. 5 dpf homozygous persephone mutants are indistinguishable from wild-type siblings, but differ in their retention of lateral line hair cells upon exposure to neomycin. The mutation in persephone maps to the chloride/bicarbonate exchanger slc4a1b and introduces a single Ser-to-Phe substitution in zSlc4a1b. This mutation prevents delivery of the exchanger to the cell surface and abolishes the ability of the protein to import chloride across the plasma membrane. Loss of function of zSlc4a1b reduces hair cell death caused by exposure to the aminoglycosides neomycin, kanamycin, and gentamicin, and the chemotherapeutic drug cisplatin. Pharmacological block of anion transport with the disulfonic stilbene derivatives DIDS and SITS, or exposure to exogenous bicarbonate, also protects hair cells against damage. Both persephone mutant and DIDS-treated wild-type larvae show reduced uptake of labeled aminoglycosides. persephone mutants also show reduced FM1-43 uptake, indicating a potential impact on mechanotransduction-coupled activity in the mutant. We propose that tight regulation of the ionic environment of sensory hair cells, mediated by zSlc4a1b activity, is critical for their sensitivity to aminoglycoside antibiotics.

  10. Phenotypic plasticity of gas exchange pattern and water loss in Scarabaeus spretus (Coleoptera: Scarabaeidae): deconstructing the basis for metabolic rate variation.

    PubMed

    Terblanche, John S; Clusella-Trullas, Susana; Chown, Steven L

    2010-09-01

    Investigation of gas exchange patterns and modulation of metabolism provide insight into metabolic control systems and evolution in diverse terrestrial environments. Variation in metabolic rate in response to environmental conditions has been explained largely in the context of two contrasting hypotheses, namely metabolic depression in response to stressful or resource-(e.g. water) limited conditions, or elevation of metabolism at low temperatures to sustain life in extreme conditions. To deconstruct the basis for metabolic rate changes in response to temperature variation, here we undertake a full factorial study investigating the longer- and short-term effects of temperature exposure on gas exchange patterns. We examined responses of traits of gas exchange [standard metabolic rate (SMR); discontinuous gas exchange (DGE) cycle frequency; cuticular, respiratory and total water loss rate (WLR)] to elucidate the magnitude and form of plastic responses in the dung beetle, Scarabaeus spretus. Results showed that short- and longer-term temperature variation generally have significant effects on SMR and WLR. Overall, acclimation to increased temperature led to a decline in SMR (from 0.071+/-0.004 ml CO(2) h(-1) in 15 degrees C-acclimated beetles to 0.039+/-0.004 ml CO(2) h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) modulated by reduced DGE frequency (15 degrees C acclimation: 0.554+/-0.027 mHz, 20 degrees C acclimation: 0.257+/-0.030 mHz, 25 degrees C acclimation: 0.208+/-0.027 mHz recorded at 20 degrees C), reduced cuticular WLRs (from 1.058+/-0.537 mg h(-1) in 15 degrees C-acclimated beetles to 0.900+/-0.400 mg h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) and reduced total WLR (from 4.2+/-0.5 mg h(-1) in 15 degrees C-acclimated beetles to 3.1+/-0.5 mg h(-1) in 25 degrees C-acclimated beetles measured at 25 degrees C). Respiratory WLR was reduced from 2.25+/-0.40 mg h(-1) in 15 degrees C-acclimated beetles to 1.60+/-0.40 mg h

  11. Unexpected sensitivity of the annual net ecosystem exchange to the high frequency loss corrections in a grazed grassland site in Belgium

    NASA Astrophysics Data System (ADS)

    Mamadou, Ossenatou; Gourlez de la Motte, Louis; De Ligne, Anne; Bernard, Heineisch; Aubinet, Marc

    2016-04-01

    Although widely used to measure CO2 and other gas fluxes, the eddy covariance technique still needs methodological improvements. This research focuses on the high frequency loss corrections, which are especially important when using a closed-path infrared gas analyzer. We compared three approaches to implement these corrections for CO2 fluxes and evaluated their impact on the carbon balance at the Dorinne Terrestrial Observatory (DTO), an intensively grazed grassland site in Belgium. The carbon balance at DTO is also the object of a separate analysis (Gourlez de la Motte et al., Geophysical Research Abstract, Vol. 18, EGU2016-6813-1, 2016). In the first approach, the computation of correction factors was based on the measured sensible heat cospectra ('local' cospectra), whereas the other two were based on theoretical models (Kaimal et al., 1972). The correction approaches were validated by comparing the nighttime eddy covariance CO2 fluxes corrected with each approach and in situ soil respiration measurements. We found that the local cospectra differed from the Kaimal theoretical shape, although the site could not be considered 'difficult' (i.e., fairly flat, homogeneous, low vegetation, sufficient measurement height), appearing less peaked in the inertial subrange. This difference greatly affected the correction factor, especially for night fluxes. Night fluxes measured by eddy covariance were found to be in good agreement with in situ soil respiration measurements when corrected with local cospectra and to be overestimated when corrected with Kaimal cospectra. As the difference between correction factors was larger in stable than unstable conditions, this acts as a selective systematic error and has an important impact on annual fluxes. On the basis of a 4-year average, at DTO, the errors reach 71-150 g C m-2 y-1 for net ecosystem exchange (NEE), 280-562 g C m-2 y-1 for total ecosystem respiration (TER) and 209-412 g C m-2 y-1 for gross primary productivity (GPP

  12. Measurement and calculation of absolute single- and double-charge-exchange cross sections for O6 + ions at 1.17 and 2.33 keV/u impacting He and H2

    NASA Astrophysics Data System (ADS)

    Machacek, J. R.; Mahapatra, D. P.; Schultz, D. R.; Ralchenko, Yu.; Chutjian, A.; Simcic, J.; Mawhorter, R. J.

    2014-11-01

    Absolute single- and double-charge-exchange cross sections for the astrophysically prominent O6 + ion with the atomic and molecular targets He and H2 are reported. These collisions give rise to x-ray emissions in the interplanetary medium, planetary atmospheres, and comets as they approach the sun. Measurements have been carried out using the Caltech Jet Propulsion Laboratory electron cyclotron resonance ion source with O6 + at energies of 1.17 and 2.33 keV/u characteristic of the slow and fast components of the solar wind. Absolute charge-exchange (CE) data are derived from knowledge of the target gas pressure, target path length, incident ion current, and charge-exchanged ion currents. These data are compared with results obtained using the n -electron classical trajectory Monte Carlo method. The radiative and Auger evolution of ion populations following one- and two-electron transfers is calculated with the time-dependent collisional-radiative code nomad using atomic data from the flexible atomic code. Calculated CE emission spectra for 100 Å <λ <1400 Å are reported as well and compared with experimental sublevel spectra and cross sections.

  13. Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement

    NASA Astrophysics Data System (ADS)

    Kawauchi, Satoko; Nishidate, Izumi; Uozumi, Yoichi; Nawashiro, Hiroshi; Ashida, Hiroshi; Sato, Shunichi

    2013-01-01

    Brain tissue is highly vulnerable to ischemia/hypoxia, and real-time monitoring of its viability is important. By fiber-based measurements for rat brain, we previously observed a unique triphasic reflectance change (TRC) after a certain period of time after hypoxia. After TRC, rats could not be rescued, suggesting that TRC can be used as an indicator of loss of brain tissue viability. In this study, we investigated this diffuse-reflectance change due to hypoxia in three parts. First, we developed and validated a theoretical method to quantify changes in the absorption and reduced scattering coefficients involved in TRC. Second, we performed charge-coupled-device-based reflectance imaging of the rat brain during hypoxia followed by reoxygenation to examine spatiotemporal characteristics of the reflectance and its correlation with reversibility of brain tissue damage. Third, we made simultaneous imaging and fiber-based measurement of the reflectance for the rat to compare signals obtained by these two modalities. We observed a nontriphasic reflectance change by the imaging, and it was associated with brain tissue viability. We found that TRC measured by the fibers preceded the reflectance-signal change captured by the imaging. This time difference is attributable to the different observation depths in the brain with these two methods.

  14. Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at $${\\sqrt{s} = 8}$$ s = 8 TeV using the ATLAS experiment

    DOE PAGES

    Aad, G.

    2015-09-03

    Many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data samplemore » corresponding to an integrated luminosity of \\(18.4\\) fb\\(^{-1}\\) of pp collisions at \\(\\sqrt{s} = 8\\) TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 \\(\\%\\) confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.« less

  15. Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at ${\\sqrt{s} = 8}$ s = 8 TeV using the ATLAS experiment

    SciTech Connect

    Aad, G.

    2015-09-03

    Many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data sample corresponding to an integrated luminosity of \\(18.4\\) fb\\(^{-1}\\) of pp collisions at \\(\\sqrt{s} = 8\\) TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 \\(\\%\\) confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.

  16. Soft X-ray study of solar wind charge exchange from the Earth's magnetosphere : Suzaku observations and a future X-ray imaging mission concept

    NASA Astrophysics Data System (ADS)

    Ezoe, Y.; Ishisaki, Y.; Ohashi, T.; Ishikawa, K.; Miyoshi, Y.; Fujimoto, R.; Terada, N.; Kasahara, S.; Fujimoto, M.; Mitsuda, K.; Nishijo, K.; Noda, A.

    2013-12-01

    Soft X-ray observations of solar wind charge exchange (SWCX) emission from the Earth's magnetosphere using the Japanese X-ray astronomy satellite Suzaku are shown, together with our X-ray imaging mission concept to characterize the solar wind interaction with the magnetosphere. In recent years, the SWCX emission from the Earth's magnetosphere, originally discovered as unexplained noise during the soft X-ray all sky survey (Snowden et al. 1994), is receiving increased attention on studying geospace. The SWCX is a reaction between neutrals in exosphere and highly charged ions in the magnetosphere originated from solar wind. Robertson et al. (2005) modeled the SWCX emission as seen from an observation point 50 Re from Earth. In the resulting X-ray intensities, the magnetopause, bow shock and cusp were clearly visible. High sensitivity soft X-ray observation with CCDs onboard recent X-ray astronomy satellites enables us to resolve SWCX emission lines and investigate time correlation with solar wind as observed with ACE and WIND more accurately. Suzaku is the 5th Japanese X-ray astronomy satellite launched in 2005. The line of sight direction through cusp is observable, while constraints on Earth limb avoidance angle of other satellites often limits observable regions. Suzaku firstly detected the SWCX emission while pointing in the direction of the north ecliptic pole (Fujimoto et al. 2007). Using the Tsyganenko 1996 magnetic field model, the distance to the nearest SWCX region was estimated as 2-8 Re, implying that the line of sight direction can be through magnetospheric cusp. Ezoe et al. (2010) reported SWCX events toward the sub-solar side of the magnetosheath. These cusp and sub-solar side magnetosheath regions are predicted to show high SWCX fluxes by Robertson et al. (2005). On the other hand, Ishikawa et al. (2013) discovered a similarly strong SWCX event when the line of sight direction did not transverse these two regions. Motivated by these detections

  17. XMM-Newton and Suzaku X-Ray Shadowing Measurements of the Solar Wind Charge Exchange, Local Bubble, and Galactic Halo Emission

    NASA Astrophysics Data System (ADS)

    Henley, David B.; Shelton, Robin L.

    2015-07-01

    We present results from a sample of XMM-Newton and Suzaku observations of interstellar clouds that cast shadows in the soft X-ray background (SXRB)—the first uniform analysis of such a sample from these missions. By fitting to the on- and off-shadow spectra, we separated the foreground and Galactic halo components of the SXRB. We tested different foreground models—two solar wind charge exchange (SWCX) models and a Local Bubble (LB) model. We also examined different abundance tables. We found that Anders & Grevesse abundances, commonly used in previous SXRB studies, may result in overestimated foreground brightnesses and halo temperatures. We also found that assuming a single solar wind ionization temperature for a SWCX model can lead to unreliable results. We compared our measurements of the foreground emission with predictions of the SWCX emission from a smooth solar wind, finding only partial agreement. Using available observation-specific SWCX predictions and various plausible assumptions, we placed an upper limit on the LB's O vii intensity of ∼0.8 {{photons}} {{{cm}}}-2 {{{s}}}-1 {{{sr}}}-1 (90% confidence). Comparing the halo results obtained with SWCX and LB foreground models implies that, if the foreground is dominated by SWCX and is brighter than ∼1.5× {10}-12 {{erg}} {{{cm}}}-2 {{{s}}}-1 {{{deg}}}-2 (0.4–1.0 {{keV}}), then using an LB foreground model may bias the halo temperature upward and the 0.5–2.0 {{keV}} surface brightness downward by ∼(0.2-0.3)× {10}6 {{K}} and ∼(1-2)× {10}-12 {{erg}} {{{cm}}}-2 {{{s}}}-1 {{{deg}}}-2, respectively. Similarly, comparing results from different observatories implies that there may be uncertainties in the halo temperature and surface brightness of up to ∼0.2× {10}6 {{K}} and ∼25%, respectively, in addition to the statistical uncertainties. These uncertainties or biases may limit the ability of X-ray measurements to discriminate between Galactic halo models.

  18. 26 CFR 1.1231-1 - Gains and losses from the sale or exchange of certain property used in the trade or business.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... hand at the close of the taxable year, or property held by the taxpayer primarily for sale to customers... with respect to transactions between related taxpayers) or section 1091 (relating to losses from...

  19. Microscopic mechanism of path-dependence on charge-discharge history in lithium iron phosphate cathode analysis using scanning transmission electron microscopy and electron energy-loss spectroscopy spectral imaging

    NASA Astrophysics Data System (ADS)

    Honda, Yoshitake; Muto, Shunsuke; Tatsumi, Kazuyoshi; Kondo, Hiroki; Horibuchi, Kayo; Kobayashi, Tetsuro; Sasaki, Tsuyoshi

    2015-09-01

    We revisited the "path-dependence" problem, i.e., the differing polarization observed in LiFePO4 cathode charge/discharge curves depending on the electrochemical treatment history of the material. The phase distributions of the active material particles with different charge/discharge histories in the LiFePO4 cathode were investigated through spectral imaging (SI) using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). The STEM-EELS-SI experiments revealed that LiFePO4 (LFP) and FePO4 (FP) almost always coexist in the individual primary particles of Li0.5FePO4 (50% state of charge (SOC)) electrodes, forming core/shell structures. This is unlike the conventional domino-cascade model, in that LFP-inside/FP-outside is observed in the lithium-extracted Li0.5FePO4 particles, whereas FP-inside/LFP-outside is seen in the lithium-inserted Li0.5FePO4 particles. We examined the particle-size dependence of the core/total volume ratio of each Li0.5FePO4 particle, and the essential features of the path-dependent charge/discharge curves were semi-quantitatively reproduced by a simple static model that considered the ionic conductivity of the shell phase.

  20. Charged-particle energy loss by the excitation of surface magnetoplasmons in a structure with two- and three-dimensional plasmas

    SciTech Connect

    Averkov, Yu. O. Prokopenko, Yu. V.; Yakovenko, V. M.

    2015-10-15

    Electron energy loss by the excitation of surface magnetoplasma oscillations by an electron moving along a static magnetic field in vacuum over a two-dimensional plasma layer on the surface of three-dimensional plasma half-space has been studied theoretically. Electron energy loss by the excitation of surface magnetoplasmons has been calculated in the electrostatic approximation. It has been shown that the type of the dispersion law of electrons in such a plasma (quadratic for a two-dimensional Drude gas or linear for graphene) can be determined from the qualitative character of the dependence of the maximum of the spectral density of this loss on the electron density in the two-dimensional plasma.

  1. Superradiance from a charged dilation black hole

    SciTech Connect

    Shiraishi, K. )

    1992-12-07

    In this paper, the authors study the behavior of the wave function of charged Klein-Gordon field around a charge dilaton black hole. The rate of spontaneous charge loss is estimated for large black hole case.

  2. Loss of beam ions to the inside of the PDX (Poloidal Divertor Experiment) tokamak during the fishbone instability

    SciTech Connect

    Heidbrink, W.W.; Beiersdorfer, P.

    1986-11-01

    Using data from two vertical charge-exchange detectors on the Poloidal Divertor Experiment (PDX), we have identified a set of conditions for which loss of beam ions inward in major radius is observed during the fishbone instability. Previously, it was reported that beam ions were lost only to the outside of the PDX tokamak.

  3. Contribution of charge-transfer processes to ion-induced electron emission

    SciTech Connect

    Roesler, M.

    1996-12-01

    Charge changing events of ions moving inside metals are shown to contribute significantly to electron emission in the intermediate velocity regime via electrons coming from projectile ionization. Inclusion of equilibrium charge state fractions, together with two-electron Auger processes and resonant-coherent electron loss from the projectile, results in reasonable agreement with previous calculations for frozen protons, though a significant part of the emission is now interpreted in terms of charge exchange. The quantal character of the surface barrier transmission is shown to play an important role. The theory compares well with experimental observations for {ital H} projectiles. {copyright} {ital 1996 The American Physical Society.}

  4. Reduction of helium loss from a superconducting accelerating cavity during initial cool-down and cryostat exchange by pre-cooling the re-condensing cryostat

    NASA Astrophysics Data System (ADS)

    O'Rourke, B. E.; Minehara, E. J.; Hayashizaki, N.; Oshima, N.; Suzuki, R.

    2015-03-01

    A Zero-Boil-Off (ZBO) cryostat is designed to realize a compact, stand-alone cryogenic system for the AIST superconducting accelerator (SCA). Under normal operation there is no evaporative helium loss from the cryomodule and therefore operating costs associated with the supply of liquid helium can be eliminated. The only significant loss of helium from the module occurs during the initial cavity cool-down procedure or when the re-condensing cryostat is replaced. It takes about 3 h to cool down the cryostat head from room temperature (300 K) to 4 K. During this time around 100 L of liquid helium is lost due to evaporation. By pre-cooling the cryostat inside a low heat load vacuum tube before transfer to the cryomodule, this evaporative loss could be essentially eliminated, significantly reducing the volume of liquid helium required for the initial cryomodule cool-down. The pre-cooling system also provides an efficient method to test the cryostat prior to use.

  5. High Temperature Thermosetting Polyimide Nanocomposites Prepared with Reduced Charge Organoclay

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi; Liang, Margaret I.

    2005-01-01

    The naturally occurring sodium and calcium cations found in bentonite clay galleries were exchanged with lithium cations. Following the cation exchange, a series of reduced charge clays were prepared by heat treatment of the lithium bentonite at 130 C, 150 C, or 170 C. Inductively coupled plasma (ICP) analysis showed that heating the lithium clay at elevated temperatures reduced its cation exchange capacity. Ion exchange of heat-treated clays with either a protonated alkyl amine or a protonated aromatic diamine resulted in decreasing amounts of the organic modifier incorporated into the lithium clay. The level of silicate dispersion in a thermosetting polyimide matrix was dependent upon the temperature of Li-clay heat treatment as well as the organic modification. In general, clays treated at 150 C or 170 C, and exchanged with protonated octadcylamine or protonated 2,2'-dimethlybenzidine (DMBZ) showed a higher degree of dispersion than clays treated at 130 C, or exchanged with protonated dodecylamine. Dynamic mechanical analysis showed little change in the storage modulus or T(sub g) of the nanocomposites compared to the base resin. However, long term isothermal aging of the samples showed a significant decrease in the resin oxidative weight loss. Nanocomposite samples aged in air for 1000 hours at 288 C showed of to a decrease in weight loss compared to that of the base resin. This again was dependent on the temperature at which the Li-clay was heated and the choice of organic modification.

  6. Anion exchange membrane

    DOEpatents

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  7. 47 CFR 69.124 - Interconnection charge.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Interconnection charge. 69.124 Section 69.124... Computation of Charges § 69.124 Interconnection charge. (a) Until December 31, 2001, local exchange carriers not subject to price cap regulation shall assess an interconnection charge expressed in dollars...

  8. Charge exchange in 3-30 keV H+ scattering off clean and AlF3 -covered Al(111) surfaces I. Experimental study

    NASA Astrophysics Data System (ADS)

    Lugo, J. O.; Goldberg, E. C.; Sánchez, E. A.; Grizzi, O.

    2005-07-01

    Ion scattering spectroscopy with time-of-flight analysis has been used to study the deposition of a thin AlF3 insulating film on an Al(111) sample, and to measure the ion fractions for 3-30 keV H+ projectiles scattered off both the metallic and the insulating surface. The total ion fraction measured for the clean surface at a scattering angle of 108° is Γ˜12% , composed mainly of negative ions. For AlF3 film thickness greater than 2 ML, the ion fraction increases, being in this case mainly composed of positive ions ( Γ+=35% , Γ-=3% ). These changes are interpreted in terms of a competition of resonant electron capture and loss processes between surface and hydrogen electron states.

  9. Comparison of NSTX FIDA, Charge Exchange, and Neutron Fluxes with Calculated Signals Based on CQL3D-FOW Distribution Functions

    NASA Astrophysics Data System (ADS)

    Harvey, R. W.; Petrov, Yu. V.; Kinsey, J. E.; Liu, D.; Heidbrink, W. W.; Taylor, G.; Bonoli, P. T.

    2014-10-01

    Ion distribution function calculations with CQL3D have been substantially advanced through implementation of guiding-center-orbit-based Fokker-Planck Coefficients. The resulting finite-orbit-width (FOW) calculations are carried out with a fast CQL3D-Hybrid-FOW option, and in a slower but neoclassically complete (except no Er yet) CQL3D-FOW option. Good comparison between time-dependent Fast Ion Diagnostic FIDA, NPA, and neutron signals resulting from neutral beaminjection(NBI) and high harmonic fast wave (HHFW) power injected into the NSTX spherical tokamak have been simulated with the CQL3D-Hybrid-FOW, using only the FOW effects on QL diffusion, and particle losses, direct and CX. Comparisons are also made with recent CQL3D-FOW results, as well as between the original FIDA calculation code and a recent fortran version. Supported by USDOE Grants SC0006614, ER54744, and ER44649.

  10. Momentum-Dependent Charge Transfer Excitations in Sr2CuO 2Cl2 Angle-Resolved Electron Energy Loss Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Y. Y.; Zhang, F. C.; Dravid, V. P.; Ng, K. K.; Klein, M. V.; Schnatterly, S. E.; Miller, L. L.

    1996-08-01

    Electron-hole pair excitations in the insulating cuprates Sr2CuO2Cl2 were investigated by angle-resolved electron energy loss spectroscopy. The optically allowed and optically forbidden transitions were observed to be strongly anisotropic in Cu-O2 plane. The former show a large energy dispersion ~1.5 eV along [110], and the latter appear at a higher energy position (~4.5 eV) only along [100], but not along [110]. We interpret these results as transitions involving excitons. A small exciton model is examined to explain both the observed features.

  11. Electron Cooling of Highly Charged Ions in Penning Traps

    SciTech Connect

    Zwicknagel, Guenter

    2006-10-18

    For recent and planned experiments like the CPT-tests with antihydrogen at CERN (ATHENA, ATRAP) or the QED-tests and various other investigations with slow highly charged ions at GSI (HTTRAP), the ions or antiprotons are cooled with electrons or positrons in Penning traps. In many of these applications an efficient and fast cooling is crucial. In particular for electron cooling of highly charged ions, like e.g. of U92+ in HITRAP, sufficiently large cooling rates are mandatory for avoiding too much losses by recombination or charge exchange processes. Here we present calculations of electron cooling and recombination losses of an ensemble of ions in a Penning traps based on a detailed description of the cooling force and the actual radiative ion-electron recombination rate. We focus on the cooling of highly charged ions, namely bare Uranium, in HITRAP. Both the associated cooling times and recombination losses strongly depend on the density of the electrons and the ratio of the number of ions to the number of electrons in the trap. Our analysis shows that electron cooling of bare Uranium with an initial energy of a few keV/u is feasible with a cooling time less than about a second at less than 10 percent recombination losses.

  12. Ion exchange phenomena

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  13. 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)

    SciTech Connect

    Stratton, B.C.; Fonck, R.J.; Ramsey, A.T.; Synakowski, E.J.; Grek, B.; Hill, K.W.; Johnson, D.W.; Mansfield, D.K.; Park, H.; Taylor, G.; Valanju, P.M. . Plasma Physics Lab.; Texas Univ., Austin, TX . Fusion Research Center)

    1989-09-01

    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 discharges, the contribution of beam halo neutrals to the line brightness was significant and therefore had to be included in the modeling of the data. Carbon concentrations have been measured in discharges with I{sub p} = 1.0-1.6 MA and beam power in the range of 2.6-30 MW, including a number of supershots. The results are in good agreement with carbon concentrations deduced from the visible bremsstrahlung Z{sub eff} and metallic impurity concentrations measured by x-ray pulse-height analysis, demonstrating the reliability of the atomic rates used in the beam attenuation and line excitation calculations. Carbon is the dominant impurity species in these discharges; the oxygen concentration measured via CXRS in a high beam power case was 0.0006 of n{sub e}, compard to 0.04 for carbon. Trends with I{sub p} and beam power in the carbon concentration and the inferred deuteron concentration are presented. The carbon concentration is independent of I{sub p} and decreases from 0.13 at 2.6 MW beam power to 0.04 at 30 MW, while the deuteron concentration increases from 0.25 to 0.75 over the same range of beam power. These changes are primarily the result of beam particle fueling, as the carbon density did not vary significantly with beam power. The time evolutions of the carbon and deuteron concentrations during two high power beam pulses, one which exhibited a carbon bloom and one which did not, are compared. 30 refs., 12 figs., 2 tabs.

  14. Hearing Loss

    MedlinePlus

    ... version of this page please turn Javascript on. Hearing Loss What is Hearing Loss? Hearing loss is a common problem caused by ... sec Click to watch this video Types of Hearing Loss Hearing loss comes in many forms. It can ...

  15. Tuning a High Transmission Ion Guide to Prevent Gas-Phase Proton Exchange During H/D Exchange MS Analysis

    NASA Astrophysics Data System (ADS)

    Guttman, Miklos; Wales, Thomas E.; Whittington, Dale; Engen, John R.; Brown, Jeffery M.; Lee, Kelly K.

    2016-04-01

    Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) for protein structural analysis has been adopted for many purposes, including biopharmaceutical development. One of the benefits of examining amide proton exchange by mass spectrometry is that it can readily resolve different exchange regimes, as evidenced by either binomial or bimodal isotope patterns. By careful analysis of the isotope pattern during exchange, more insight can be obtained on protein behavior in solution. However, one must be sure that any observed bimodal isotope patterns are not artifacts of analysis and are reflective of the true behavior in solution. Sample carryover and certain stationary phases are known as potential sources of bimodal artifacts. Here, we describe an additional undocumented source of deuterium loss resulting in artificial bimodal patterns for certain highly charged peptides. We demonstrate that this phenomenon is predominantly due to gas-phase proton exchange between peptides and bulk solvent within the initial stages of high-transmission conjoined ion guides. Minor adjustments of the ion guide settings, as reported here, eliminate the phenomenon without sacrificing signal intensity. Such gas-phase deuterium loss should be appreciated for all HDX-MS studies using such ion optics, even for routine studies not focused on interpreting bimodal spectra.

  16. A new technique for the study of charge transfer in multiply charged ion-ion collisions

    SciTech Connect

    Shinpaugh, J.L.; Meyer, F.W.; Datz, S.

    1994-12-31

    While large cross sections (>10{sup {minus}16} cm{sup 2}) have been predicted for resonant charge transfer in ion-ion collisions, no experimental data exist for multiply charged systems. A novel technique is being developed at the ORNL ECR facility to allow study of symmetric charge exchange in multiply charged ion-ion collisions using a single ion source. Specific intra-beam charge transfer collisions occurring in a well-defined interaction region labeled by negative high voltage are identified and analyzed by electrostatic analysis in combination with ion time-of-flight coincidence detection of the collision products. Center-of-mass collision energies from 400 to 1000 eV are obtained by varying source and labeling-cell voltages. In addition, by the introduction of a target gas into the high-voltage cell, this labeling-voltage method allows measurement of electron-capture and -loss cross sections for ion-atom collisions. Consequently, higher collision energies can be investigated without the requirement of placing the ECR source on a high-voltage platform.

  17. Line10 Charge Injection Biases

    NASA Astrophysics Data System (ADS)

    Baggett, Sylvia

    2012-10-01

    Radiation damage on-orbit, in the form of charge traps, gradually reduces the charge transfer efficiency {CTE} of CCDs over time. In WFC3, one option for mitigating CTE losses is charge injection i.e. electronically inserting charge every Nth row. The benefit of this method is the significantly lower noise penalty, much less than the traditional Poissonian noise imparted by a pre- or post-flash of the same charge level. This program acquires the calibration data necessary to support science observations using charge injection.

  18. Radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emissions following charge exchange between C6+ and Kr

    NASA Astrophysics Data System (ADS)

    Andrianarijaona, V. M.; Wulf, D.; McCammon, D.; Seely, D. G.; Havener, C. C.

    2015-05-01

    The radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emission following charge exchange (CX) between C6+ and Kr are reported for collision energies between approximately 320 and 46,000 eV/u. The corresponding collision velocities (250-3000 km/s) are characteristic of the solar wind. X-ray spectra were obtained at the Oak Ridge National Laboratory Multicharged Ion Research Facility using a microcalorimeter X-ray detector with a resolution on the order of 10 eV FWHM. The measured Ly-ε/Ly-α is zero for all considered energies and suggests that very little, if any, capture to 6p occurs. The measured Ly-β/Ly-α and Ly-γ/Ly-α ratios intersect and form a well resolved node around (950 ± 50) km/s, which could be used as an astrophysical velocity indicative tool. The results reported here are compared to calculations for C6+ + H since no published theory for C6+ + Kr is known to exist. Double-electron-capture (DEC) and other multi-electron processes are possible. True double capture is estimated to be only 10% of the single-electron-capture (SEC).

  19. The roles of electronic exchange and correlation in charge-transfer- to-solvent dynamics: Many-electron nonadiabatic mixed quantum/classical simulations of photoexcited sodium anions in the condensed phase

    SciTech Connect

    Glover, William J.; Larsen, Ross E.; Schwartz, Benjamin J.

    2008-10-28

    The charge-transfer-to-solvent (CTTS) reactions of solvated atomic anions serve as ideal models for studying the dynamics of electron transfer: The fact that atomic anions have no internal degrees of freedom provides one of the most direct routes to understanding how the motions of solvent molecules influence charge transfer, and the relative simplicity of atomic electronic structure allows for direct contact between theory and experiment. To date, molecular dynamics simulations of the CTTS process have relied on a single-electron description of the atomic anion--only the electron involved in the charge transfer has been treated quantum mechanically, and the electronic structure of the atomic solute has been treated via pseudopotentials. In this paper, we examine the severity of approximating the electronic structure of CTTS anions with a one-electron model and address the role of electronic exchange and correlation in both CTTS electronic structure and dynamics. To do this, we perform many-electron mixed quantum/classical molecular dynamics simulations of the ground- and excited-state properties of the aqueous sodium anion (sodide). We treat both of the sodide valence electrons quantum mechanically and solve the Schroedinger equation using configuration interaction with singles and doubles (CISD), which provides an exact solution for two electrons. We find that our multielectron simulations give excellent general agreement with experimental results on the CTTS spectroscopy and dynamics of sodide in related solvents. We also compare the results of our multielectron simulations to those from one-electron simulations on the same system [C. J. Smallwood et al., J. Chem. Phys. 119, 11263 (2003)] and find substantial differences in the equilibrium CTTS properties and the nonadiabatic relaxation dynamics of one- and two-electron aqueous sodide. For example, the one-electron model substantially underpredicts the size of sodide, which in turn results in a dramatically

  20. 77 FR 56896 - Self-Regulatory Organizations; EDGA Exchange, Inc.; Notice of Filing and Immediate Effectiveness...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-14

    ... orders that remove liquidity from EDGA using eligible routing strategies. The Exchange also proposes to... strategies. The Exchange formerly did not assess a charge for Flag CR. The Exchange proposes to offer Members... routing strategies. The Exchange formerly did not assess a charge for Flag PR. The Exchange proposes...