WorldWideScience

Sample records for ring current ions

  1. Ring current instabilities excited by the energetic oxygen ions

    International Nuclear Information System (INIS)

    Kakad, A. P.; Singh, S. V.; Lakhina, G. S.

    2007-01-01

    The ring current instabilities driven by the energetic oxygen ions are investigated during the magnetic storm. The electrons and protons are considered to have Maxwellian distributions, while energetic oxygen ions are having loss-cone distribution. Dispersion relation for the quasielectrostatic modes with frequencies ω>ω cp (proton cyclotron frequency) and propagating obliquely to the magnetic field is obtained. Dispersion relation is studied numerically for the storm time ring current parameters and it is found that these instabilities are most prominent during intense storms when the oxygen ions become the dominant constituents of the ring current plasma. For some typical storm-time ring current parameters, these modes can produce quasielectrostatic noise in the range of 17-220 Hz, thus providing a possible explanation of the electrostatic noise observed at the inner boundary of the ring current during magnetic storms. Further, these modes can attain saturation electric fields of the order of 100-500 μV/m, and therefore, are expected to scatter O + ions into the loss-cone giving rise to their precipitation into the atmosphere, thus contributing to the ring current decay

  2. Radial transport of storm time ring current ions

    Science.gov (United States)

    Lui, A. T. Y.

    1993-01-01

    Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer spacecraft, which monitored protons, helium ions, and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions. From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region can be accounted for by an inward displacement of the ring current population by 0.5 to 3.5 R(E). There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter time scale than that for a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations.

  3. Ring Current He Ion Control by Bounce Resonant ULF Waves

    Science.gov (United States)

    Kim, Hyomin; Gerrard, Andrew J.; Lanzerotti, Louis J.; Soto-Chavez, Rualdo; Cohen, Ross J.; Manweiler, Jerry W.

    2017-12-01

    Ring current energy He ion (˜65 keV to ˜520 keV) differential flux data from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft show considerable variability during quiet solar wind and geomagnetic time periods. Such variability is apparent from orbit to orbit (˜9 h) of the spacecraft and is observed to be ˜50-100% of the nominal flux. Using data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument, also aboard the Van Allen Probes spacecraft, we identify that a dominant source of this variability is from ULF waveforms with periods of tens of seconds. These periods correspond to the bounce resonant timescales of the ring current He ions being measured by RBSPICE. A statistical survey using the particle and field data for one full spacecraft precession period (approximately 2 years) shows that the wave and He ion flux variations are generally anticorrelated, suggesting the bounce resonant pitch angle scattering process as a major component in the scattering of He ions.

  4. Energetic ion injection and formation of the storm-time symmetric ring current

    Directory of Open Access Journals (Sweden)

    L. Xie

    2006-12-01

    Full Text Available An extensive study of ring current injection and intensification of the storm-time ring current is conducted with three-dimensional (3-D test particle trajectory calculations (TPTCs. The TPTCs reveal more accurately the process of ring current injection, with the main results being the following: (1 an intense convection electric field can effectively energize and inject plasma sheet particles into the ring current region within 1–3 h. (2 Injected ions often follow chaotic trajectories in non-adiabatic regions, which may have implications in storm and ring current physics. (3 The shielding electric field, which arises as a consequence of enhanced convection and co-exists with the injection and convection electric field, may cause the original open trajectories of injected ions with higher energy to change into closed ones, thus playing a role in the formation of the symmetric ring current.

  5. CRRES observations of stormtime ring current ion composition

    International Nuclear Information System (INIS)

    Roeder, J.L.; Fennell, J.F.; Chen, M.W.; Grande, M.; Livi, S.; Schulz, M.

    1996-01-01

    The Magnetospheric Ion Composition Spectrometer onboard the CRRES spacecraft provided mass and charge state composition data for positive ions in the energy-per-charge range 1 endash 426 keV/e. The CRRES data is compared to the AMPTE/CCE observations during a moderately large geomagnetic storm on 4 June 1991. The results are compared to observations of large storms by CRRES and by the AMPTE/CCE spacecraft. The CRRES data show that oxygen ions formed 29% of the total measured ion energy density at L=3 endash 5 during the storm recovery phase. This result implies that domination of the plasma by oxygen ions may not be necessary to produce the observed rapid initial recovery of the Dst magnetic index. A preliminary test of the Dessler-Parker-Sckopke relation between the ion energy and the global magnetic perturbation shows that the observed particle fluxes during the 4 June 1991 storm could account for only 40 endash 70% of the variation of Dst. copyright 1996 American Institute of Physics

  6. The Effects of Hydrogen Band EMIC Waves on Ring Current H+ Ions

    Science.gov (United States)

    Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu

    2017-12-01

    Hydrogen band electromagnetic ion cyclotron (EMIC) waves have received much attention recently because they are found to frequently span larger spatial areas than the other band EMIC waves. Using test particle simulations, we study the nonlinear effects of hydrogen band EMIC waves on ring current H+ ions. A dimensionless parameter R is used to characterize the competition between wave-induced and adiabatic motions. The results indicate that there are three regimes of wave-particle interactions for typical 35 keV H+ ions at L = 5: diffusive (quasi-linear) behavior when αeq ≤ 35° (R ≥ 2.45), the nonlinear phase trapping when 35° < αeq < 50° (0.75 < R < 2.45), and both the nonlinear phase bunching and phase trapping when αeq ≥ 50° (R ≤ 0.75). The phase trapping can transport H+ ions toward large pitch angle, while the phase bunching has the opposite effect. The phase-trapped H+ ions can be significantly accelerated (from 35 keV to over 500 keV) in about 4 min and thus contribute to the formation of high energy components of ring current ions. The results suggest that the effect of hydrogen band EMIC waves is not ignorable in the nonlinear acceleration and resonance scattering of ring current H+ ions.

  7. Discovery of energetic molecular ions (NO+ and O2+) in the storm time ring current

    International Nuclear Information System (INIS)

    Klecker, B.; Moebius, E.; Hovestadt, D.; Scholer, M.; Gloeckler, G.; Ipavich, F.M.

    1986-01-01

    A few hours after the onset of a large geomagnetic storm on September 4, 1984, energetic molecular ions in the mass range 28--32, predminantly NO + and O 2 + , have been discovered in the outer ring current at L--7. The data have been obtained with the time-of-flight spectrometer SULEICA on the AMPTE/IRM spacecraft. We find at 160 keV/e a mean abundance ratio of the molecular ions relative to O + ions of 0.031 +- 0.004. During quiet times no molecular ions are observed, the 1 sigma upper limit of the ratio derived by averaging over several quiet periods is 0.003. The observations demonstrate the injection of ionospheric plasma into the storm time ring current and the subsequent acceleration to energies of several hundred keV on a time scale of a few hours after the onset of the magnetic storm

  8. Observations of ions of ionospheric origin in the storm-time ring current

    International Nuclear Information System (INIS)

    Johnson, R.G.; Sharp, R.D.; Shelley, E.G.

    1977-01-01

    O + , He + , and H + ions in the energy range 0.5 to 16 keV have been observed in the storm-time ring current with an energetic ion mass spectrometer aboard the polar-orbiting S3-3 satellite. During the main phases of the 29 December 1976, 6 April 1977, and 19 April 1977 magnetic storms, the O + number density within the instrument energy range in the inner ring current (L=2.8--4.0) was larger than the H + density in the altitude range from about 5000--7000 km. At two days after the main phase of the 29 December 1976 storm, O + was still the dominant ion at MLT=14.5 hours in the L=2.6--3.4 range at altitudes near 6000 km

  9. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    Science.gov (United States)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  10. Ion transport and loss in the earth's quiet ring current. I - Data and standard model

    Science.gov (United States)

    Sheldon, R. B.; Hamilton, D. C.

    1993-01-01

    A study of the transport and loss of ions in the earth's quiet time ring current, in which the standard radial diffusion model developed for the high-energy radiation belt particles is compared with the measurements of the lower-energy ring current ions, is presented. The data set provides ionic composition information in an energy range that includes the bulk of the ring current energy density, 1-300 keV/e. Protons are found to dominate the quiet time energy density at all altitudes, peaking near L of about 4 at 60 keV/cu cm, with much smaller contributions from O(+) (1-10 percent), He(+) (1-5 percent), and He(2+) (less than 1 percent). A minimization procedure is used to fit the amplitudes of the standard electric radial diffusion coefficient, yielding 5.8 x 10 exp -11 R(E-squared)/s. Fluctuation ionospheric electric fields are suggested as the source of the additional diffusion detected.

  11. Macroscopic ion acceleration associated with the formation of the ring current in the earth's magnetosphere

    International Nuclear Information System (INIS)

    Mauk, B.H.; Meng, C.I.

    1986-01-01

    As an illustration of the operation of macroscopic ion acceleration processes within the earth's magnetosphere, the paper reviews processes thought to be associated with the formation of the earth's ring-current populations. Arguing that the process of global, quasi-curl-free convection cannot explain particle characteristics observed in the middle (geosynchronous) to outer regions, it is concluded that the transport and energization of the seed populations that give rise to the ring-current populations come about in two distinct stages involving distinct processes. Near and outside the geostationary region, the energization and transport are always associated with highly impulsive and relatively localized processes driven by inductive electric fields. The subsequent adiabatic earthward transport is driven principally by enhanced, curl-free global convection fields. 58 references

  12. Sub-keV ring current ions as the tracer of substorm injection

    Directory of Open Access Journals (Sweden)

    M. Yamauchi

    2006-03-01

    Full Text Available The dynamics of the energy-latitude dispersed sub-keV trapped ions inside the ring current region, the so-called wedge-like dispersions structure, were statistically studied using Viking satellite data. Probabilities with/without these signatures at various local times in the dayside are obtained in terms of different time-lags from the substorm activity monitored by the AE index. The structure appears in the early morning sector within a few hours after the substorm, and it slowly propagates eastward while decaying with a time scale of several hours. The result qualitatively confirmed the previous model that the wedge-like dispersions are originated from past substorm-related plasma injections into the nightside ring current region, and that the dispersion is formed when these injected plasma slowly moves eastward to the dayside by the drift motion (E×B (eastward, grad-<|B| (westward, and curvature (westward drifts. However, the appearance of the structure is twice or three times faster than the model prediction, and some structure reaches even to the evening sector. The results indicate that the start location of the drift is not as far as midnight and that the drift speed is slightly faster than the model prediction. The former means that the substorm-related increase of hot plasma in the ring current region shifts or extends to the early morning sector for large substorms, and the latter means that the substantial electric field driving the sub-keV ion drift is slightly different from the model field. We also detected the evacuating effect starting right after the substorm (or storm onset. The electric field imposed in the dayside magnetosphere seems to remove the remainder of trapped ions.

  13. Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into ring current

    Science.gov (United States)

    Cladis, J. B.; Francis, W. E.

    1985-01-01

    The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the ring current were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.

  14. Impact of the storm-time plasma sheet ion composition on the ring current energy density

    Science.gov (United States)

    Mouikis, C.; Kistler, L. M.; Petrinec, S. M.; Fuselier, S. A.; Cohen, I.

    2017-12-01

    The adiabatic inward transport of the night-side near-earth ( 6 Re) hot plasma sheet is the dominant contributor to the ring current pressure during storm times. During storm times, the plasma sheet composition in the 6 - 12 Re tail region changes due to O+ entry from the lobes (from the cusp) and the direct feeding from the night side auroral region. In addition, at substorm onset the plasma sheet O+ ions can be preferentially accelerated. We use MMS and observations during two magnetic storms, 5/8/2016 and 7/16/2017, to monitor the composition changes and energization in the 6 - 12 Re plasma sheet region. For both storms the MMS apogee was in the tail. In addition, we use subsequent Van Allen Probe observations (with apogee in the dawn and dusk respectively) to test if the 6-12 Re plasma sheet, observed by MMS, is a sufficient source of the O+ in the ring current. For this we will compare the phase space density (PSD) of the plasma sheet source population and the PSD of the inner magnetosphere at constant magnetic moment values as used in Kistler et al., [2016].

  15. Heavy ion storage rings

    International Nuclear Information System (INIS)

    Schuch, R.

    1987-01-01

    A brief overview of synchrotron storage rings for heavy ions, which are presently under construction in different accelerator laboratories is given. Ions ranging from protons up to uranium ions at MeV/nucleon energies will be injected into these rings using multiturn injection from the accelerators available or being built in these laboratories. After injection, it is planned to cool the phase space distribution of the ions by merging them with cold electron beams or laser beams, or by using stochastic cooling. Some atomic physics experiments planned for these rings are presented. 35 refs

  16. The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

    International Nuclear Information System (INIS)

    Zhao, H.; University of Colorado, Boulder, CO; Li, X.; University of Colorado, Boulder, CO; Baker, D. N.

    2015-01-01

    Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute more significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O + . This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.

  17. Comparative analysis of long-time variations of multicomponent ion ring current according to data of geostationary Gorizont satellite

    International Nuclear Information System (INIS)

    Kovtyukh, A.S.; Panasyuk, M.I.; Vlasova, N.A.; Sosnovets, Eh.N.

    1990-01-01

    Long-time variations of the fluxes of the H + , [N,O] 2+ and [C,N,O] 6 6 + ions with energy E/Q∼60-120 keV/e measured by the GORIZONT (1985-07A) satellite in the geostationary orbit at noon time are analyzed. The results are dsicussed and are compared with current models of the formation of the Earth's ion ring current

  18. Self-Consistent Model of Magnetospheric Electric Field, Ring Current, Plasmasphere, and Electromagnetic Ion Cyclotron Waves: Initial Results

    Science.gov (United States)

    Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.; Ridley, A. J.

    2009-01-01

    Further development of our self-consistent model of interacting ring current (RC) ions and electromagnetic ion cyclotron (EMIC) waves is presented. This model incorporates large scale magnetosphere-ionosphere coupling and treats self-consistently not only EMIC waves and RC ions, but also the magnetospheric electric field, RC, and plasmasphere. Initial simulations indicate that the region beyond geostationary orbit should be included in the simulation of the magnetosphere-ionosphere coupling. Additionally, a self-consistent description, based on first principles, of the ionospheric conductance is required. These initial simulations further show that in order to model the EMIC wave distribution and wave spectral properties accurately, the plasmasphere should also be simulated self-consistently, since its fine structure requires as much care as that of the RC. Finally, an effect of the finite time needed to reestablish a new potential pattern throughout the ionosphere and to communicate between the ionosphere and the equatorial magnetosphere cannot be ignored.

  19. Adiabatic compression of ion rings

    International Nuclear Information System (INIS)

    Larrabee, D.A.; Lovelace, R.V.

    1982-01-01

    A study has been made of the compression of collisionless ion rings in an increasing external magnetic field, B/sub e/ = zB/sub e/(t), by numerically implementing a previously developed kinetic theory of ring compression. The theory is general in that there is no limitation on the ring geometry or the compression ratio, lambdaequivalentB/sub e/ (final)/B/sub e/ (initial)> or =1. However, the motion of a single particle in an equilibrium is assumed to be completely characterized by its energy H and canonical angular momentum P/sub theta/ with the absence of a third constant of the motion. The present computational work assumes that plasma currents are negligible, as is appropriate for a low-temperature collisional plasma. For a variety of initial ring geometries and initial distribution functions (having a single value of P/sub theta/), it is found that the parameters for ''fat'', small aspect ratio rings follow general scaling laws over a large range of compression ratios, 1 3 : The ring radius varies as lambda/sup -1/2/; the average single particle energy as lambda/sup 0.72/; the root mean square energy spread as lambda/sup 1.1/; and the total current as lambda/sup 0.79/. The field reversal parameter is found to saturate at values typically between 2 and 3. For large compression ratios the current density is found to ''hollow out''. This hollowing tends to improve the interchange stability of an embedded low β plasma. The implications of these scaling laws for fusion reactor systems are discussed

  20. Ion Composition and Energization in the Earth's Inner Magnetosphere and the Effects on Ring Current Buildup

    Science.gov (United States)

    Keika, K.; Kistler, L. M.; Brandt, P. C.

    2014-12-01

    In-situ observations and modeling work have confirmed that singly-charged oxygen ions, O+, which are of Earth's ionospheric origin, are heated/accelerated up to >100 keV in the magnetosphere. The energetic O+ population makes a significant contribution to the plasma pressure in the Earth's inner magnetosphere during magnetic storms, although under quiet conditions H+ dominates the plasma pressure. The pressure enhancements, which we term energization, are caused by adiabatic heating through earthward transport of source population in the plasma sheet, local acceleration in the inner magnetosphere and near-Earth plasma sheet, and enhanced ion supply from the topside ionosphere. The key issues regarding stronger O+ energization than H+ are non-adiabatic local acceleration, responsible for increase in O+ temperature, and more significant O+ supply than H+, responsible for increase in O+ density. Although several acceleration mechanisms and O+ supply processes have been proposed, it remains an open question what mechanism(s)/process(es) play the dominant role in stronger O+ energization. In this paper we summarize important spacecraft observations including those from Van Allen Probes, introduces the proposed mechanisms/processes that generate O+-rich energetic plasma population, and outlines possible scenarios of O+ pressure abundance in the Earth's inner magnetosphere.

  1. Ion-ion collisions and ion storage rings

    International Nuclear Information System (INIS)

    Mowat, J.R.

    1988-01-01

    Improved understanding of fundamental ion-ion interactions is expected to emerge from research carried out with ion storage rings. In this short survey the significant advantages and unique features that make stored ions useful targets for collision experiments are reviewed and discussed. It is pointed out that improvements to existing ion-ion experiments, as well as qualitatively new experiments, should occur over the next few years as ion storage rings become available for atomic physics. Some new experiments are suggested which are difficult if not impossible with present-day technology, but which seem feasible at storage rings facilities. (orig.)

  2. Testing electric field models using ring current ion energy spectra from the Equator-S ion composition (ESIC instrument

    Directory of Open Access Journals (Sweden)

    L. M. Kistler

    Full Text Available During the main and early recovery phase of a geomagnetic storm on February 18, 1998, the Equator-S ion composition instrument (ESIC observed spectral features which typically represent the differences in loss along the drift path in the energy range (5–15 keV/e where the drift changes from being E × B dominated to being gradient and curvature drift dominated. We compare the expected energy spectra modeled using a Volland-Stern electric field and a Weimer electric field, assuming charge exchange along the drift path, with the observed energy spectra for H+ and O+. We find that using the Weimer electric field gives much better agreement with the spectral features, and with the observed losses. Neither model, however, accurately predicts the energies of the observed minima.

    Key words. Magnetospheric physics (energetic particles trapped; plasma convection; storms and substorms

  3. NRL ion ring program

    International Nuclear Information System (INIS)

    Kapetanakos, C.A.; Golden, J.; Drobot, A.; Mahaffey, R.A.; Marsh, S.J.; Pasour, J.A.

    1977-01-01

    An experiment is under way to form a storng proton ring using the 200 ka, 1.2 MeV, 50 nsec hollow proton beam recently generated at NRL. The 5 m long magnetic field configuration consists of a magnetic cusp, a compressing magnetic field, a gate field and a magnetic mirror. The midplane value of the magnetic mirror is such that the major radius of the ring will be about 10 cm. The degree of field reversal that will be achieved with 5 x 10 16 protons per pulse from the existing beam depends upon the field reversal is possible with the 600 kA proton beam that would be generated from the low inductance coaxial triode coupled to the upgraded Gamble II generator. The propagation and trapping of an intense proton beam in the experimental magnetic field configuration is investigated numerically. The results show that the self magnetic has a very pronounced effect on the dynamics of the gyrating protons

  4. Achieving Translationally Invariant Trapped Ion Rings

    Science.gov (United States)

    Urban, Erik; Li, Hao-Kun; Noel, Crystal; Hemmerling, Boerge; Zhang, Xiang; Haeffner, Hartmut

    2017-04-01

    We present the design and implementation of a novel surface ion trap design in a ring configuration. By eliminating the need for wire bonds through the use of electrical vias and using a rotationally invariant electrode configuration, we have realized a trap that is able to trap up to 20 ions in a ring geometry 45um in diameter, 400um above the trap surface. This large trapping height to ring diameter ratio allows for global addressing of the ring with both lasers and electric fields in the chamber, thereby increasing our ability to control the ring as a whole. Applying compensating electric fields, we measure very low tangential trap frequencies (less than 20kHz) corresponding to rotational barriers down to 4mK. This measurement is currently limited by the temperature of the ions but extrapolation indicates the barrier can be reduced much further with more advanced cooling techniques. Finally, we show that we are able to reduce this energy barrier sufficiently such that the ions are able to overcome it either through thermal motion or rotational motion and delocalize over the full extent of the ring. This work was funded by the Keck Foundation and the NSF.

  5. Evolution of the ring current during two geomagnetic storms

    International Nuclear Information System (INIS)

    Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

    1987-01-01

    The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

  6. High current ion sources

    International Nuclear Information System (INIS)

    Brown, I.G.

    1989-06-01

    The concept of high current ion source is both relative and evolutionary. Within the domain of one particular kind of ion source technology a current of microamperers might be 'high', while in another area a current of 10 Amperes could 'low'. Even within the domain of a single ion source type, what is considered high current performance today is routinely eclipsed by better performance and higher current output within a short period of time. Within their fields of application, there is a large number of kinds of ion sources that can justifiably be called high current. Thus, as a very limited example only, PIGs, Freemen sources, ECR sources, duoplasmatrons, field emission sources, and a great many more all have their high current variants. High current ion beams of gaseous and metallic species can be generated in a number of different ways. Ion sources of the kind developed at various laboratories around the world for the production of intense neutral beams for controlled fusion experiments are used to form large area proton deuteron beams of may tens of Amperes, and this technology can be used for other applications also. There has been significant progress in recent years in the use of microwave ion sources for high current ion beam generation, and this method is likely to find wide application in various different field application. Finally, high current beams of metal ions can be produced using metal vapor vacuum arc ion source technology. After a brief consideration of high current ion source design concepts, these three particular methods are reviewed in this paper

  7. The impact of exospheric neutral dynamics on ring current decay

    Science.gov (United States)

    Ilie, R.; Liemohn, M. W.; Skoug, R. M.; Funsten, H. O.; Gruntman, M.; Bailey, J. J.; Toth, G.

    2015-12-01

    The geocorona plays an important role in the energy budget of the Earth's inner magnetosphere since charge exchange of energetic ions with exospheric neutrals makes the exosphere act as an energy sink for ring current particles. Long-term ring current decay following a magnetic storm is mainly due to these electron transfer reactions, leading to the formation energetic neutral atoms (ENAs) that leave the ring current system on ballistic trajectories. The number of ENAs emitted from a given region of space depends on several factors, such as the energy and species of the energetic ion population in that region and the density of the neutral gas with which the ions undergo charge exchange. However, the density and structure of the exosphere are strongly dependent on changes in atmospheric temperature and density as well as charge exchange with the ions of plasmaspheric origin, which depletes the geocorona (by having a neutral removed from the system). Moreover, the radiation pressure exerted by solar far-ultraviolet photons pushes the geocoronal hydrogen away from the Earth in an anti-sunward direction to form a tail of neutral hydrogen. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. We assess the influence of geocoronal neutrals on ring current formation and decay by analysis of the predicted ENA emissions using 6 different geocoronal models and simulations from the HEIDI ring current model during storm time. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. We show that the neutral dynamics has a strong influence on the time evolution of the ring current populations as well as on the formation of energetic neutral atoms.

  8. Space Weather Effects Produced by the Ring Current Particles

    Science.gov (United States)

    Ganushkina, Natalia; Jaynes, Allison; Liemohn, Michael

    2017-11-01

    One of the definitions of space weather describes it as the time-varying space environment that may be hazardous to technological systems in space and/or on the ground and/or endanger human health or life. The ring current has its contributions to space weather effects, both in terms of particles, ions and electrons, which constitute it, and magnetic and electric fields produced and modified by it at the ground and in space. We address the main aspects of the space weather effects from the ring current starting with brief review of ring current discovery and physical processes and the Dst-index and predictions of the ring current and storm occurrence based on it. Special attention is paid to the effects on satellites produced by the ring current electrons. The ring current is responsible for several processes in the other inner magnetosphere populations, such as the plasmasphere and radiation belts which is also described. Finally, we discuss the ring current influence on the ionosphere and the generation of geomagnetically induced currents (GIC).

  9. The Ring Current Response to Solar and Interplanetary Storm Drivers

    Science.gov (United States)

    Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

    2014-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

  10. Ion production and trapping in electron rings

    International Nuclear Information System (INIS)

    Gluckstern, R.C.; Ruggiero, A.G.

    1979-08-01

    The electron beam in the VUV and X-ray rings of NSLS will ionize residual gas by collisions. Positive ions will be produced with low velocity, and will be attracted by the electron beam to the beam axis. If they are trapped in stable (transverse) orbits, they may accumulate, thereby increasing the ν/sub x,z/ of the individual electrons. Since the accumulated ions are unlikely to be of uniform density, a spread in ν/sub x,z/ will also occur. Should these effects be serious, it may be necessary to introduce clearing electrodes, although this may increase Z/n in the rings, thereby adding to longitudinal instability problems. The seriousness of the above effect for the VUV and X-ray rings is estimated

  11. Ring current proton decay by charge exchange

    Science.gov (United States)

    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.

  12. Status of the MEIC ion collider ring design

    International Nuclear Information System (INIS)

    Morozov, Vasiliy; Derbenev, Yaroslav; Harwood, Leigh; Hutton, Andrew; Lin, Fanglei; Pilat, Fulvia; Zhang, Yuhong; Cai, Yunhai; Nosochkov, Y. M.; Sullivan, Michael; Wang, M.-H.; Wienands, Uli; Gerity, James; Mann, Thomas; McIntyre, Peter; Pogue, Nathaniel; Sattarov, Akhdiyor

    2015-09-01

    We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated super-conducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

  13. Status of the MEIC ion collider ring design

    International Nuclear Information System (INIS)

    Morozov, V. S.; Derbenev, Ya. S.; Harwood, L.; Hutton, A.; Lin, F.; Pilat, F.; Zhang, Y.; Cai, Y.; Nosochkov, Y. M.; Sullivan, M.; Wang, M-H; Wienands, U.; Gerity, J.; Mann, T.; McIntyre, P.; Pogue, N. J.; Satttarov, A.

    2015-01-01

    We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated superconducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

  14. Eddy current inspection of stationary blade rings

    International Nuclear Information System (INIS)

    Krzywosz, K.J.; Hastings, S.N.

    1994-01-01

    Stationary turbine blade rings in a US power plant have experienced chloride-induced cracking. Failure analysis determined two types of cracking mechanisms: corrosion fatigue cracking confined to the leading edge of the outer shroud; and stress corrosion cracking present all over the blade surface. Fluorescent dye penetrant is typically used to detect and size cracks. However, it requires cleaning the blade rings by sandblasting to obtain reliable inspection results. Sand blasting in turn requires sealing the lower half of the turbine housing to prevent sand from contaminating the rest of the power plant components. Furthermore, both the penetrant examination and the removal of the sand are time consuming and costly. An alternative NDE technique is desirable which requires no pre-cleaning of the blade and a quick go/no-go inspection with the capability of estimating the crack length. This paper presents an innovative eddy current technique which meets the desired objectives by incorporating the use of specially designed contoured scanners equipped with an array of pancake coils. A set of eddy current pancake coils housed in three different scanners is used to manually scan and inspect the convex side of the stationary blade rings. The pancake coils are operated in a transmit/receive mode using two separate eddy current instruments. This paper presents the inspection concept, including scanner and probe designs, and test results from the various stages of multiple blade rings

  15. Comparing Sources of Storm-Time Ring Current O+

    Science.gov (United States)

    Kistler, L. M.

    2015-12-01

    The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

  16. Some remarks on the design of HIF current multiplication rings

    International Nuclear Information System (INIS)

    Reich, K.H.

    1983-12-01

    The conceptual design of heavy ion fusion drivers has now reached a state, where the overall approach has become fairly clear. One design features an RF linac plus current and beam multiplication rings. The present remarks concern the assignment of multiturn injection, beam storage and bunching to an optimized number of rings and transport lines, as well as some criteria for their designs. The main parameter constraints are discussed, showing how they can be met, although there is little flexibility at the present stage of understanding and technology. A shortened version of this report is scheduled for presentation at the ''INS International Symposium on Heavy Ion Accelerators and Their Application to Inertial Fusion'' Tokyo, January 23-27 1984. (author)

  17. HISTRAP proposal: heavy-ion storage ring for atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, D K; Alton, G D; Datz, S; Dittner, P F; Dowling, D T; Haynes, D L; Hudson, E D; Johnson, J W; Lee, I Y; Lord, R S

    1987-04-01

    HISTRAP, Heavy-Ion Storage Ring for Atomic Physics, is a proposed 46.8-m-circumference synchrotron-cooling-storage ring optimized to accelerate, decelerate, and store beams of highly charge very-heavy ions at energies appropriate for advanced atomic physics research. The ring is designed to allow studies of electron-ion, photon-ion, ion-atom, and ion-ion interactions. An electron cooling system will provide ion beams with small angular divergence and energy spread for precision spectroscopic studies and also is necessary to allow the deceleration of heavy ions to low energies. HISTRAP will have a maximum bending power of 2.0 T m and will be injected with ions from either the existing Holifield Heavy Ion Research Facility 25-MV tandem accelerator or from a dedicated ECR source and 250 keV/nucleon RFQ linac.

  18. Small electrostatic storage rings; also for highly charged ions?

    International Nuclear Information System (INIS)

    Moeller, S.P.; Pedersen, U.V.

    2001-01-01

    Two years ago, a small electrostatic storage ring ELISA (electrostatic ion storage ring, Aarhus) was put into operation. The design of this small 7 m circumference ring was based on electrostatic deflection plates and quadrupoles. This is in contrast to the larger ion storage rings, which are based on magnetic focusing and deflection. The result is a small, relatively inexpensive, storage ring being able to store ions of any mass and any charge at low energy ( -11 mbar resulting in storage times of several tens of seconds for singly charged ions. The maximum number of singly charged ions that can be stored is a few 10 7 . Several experiments have already been performed in ELISA. These include lifetime studies of metastable ions and studies of fullerenes and metal-cluster ions. Lasers are also used for excitation of the circulating ions. Heating/cooling of the ring is possible. Cooling of the ring leads to significantly lower pressures, and correspondingly longer lifetimes. A change of the temperature of the vacuum chambers surrounding the ion beam also leads to a change of the spectrum of the black-body radiation, which has a significant influence on weakly bound negative ions. At the time of writing, at least two other electrostatic storage rings are being built, and more are planned. In the following, the electrostatic storage ring ELISA will be described, and results from some of the initial experiments demonstrating the performance will be shown. The relative merits of such a ring, as opposed to the larger magnetic rings and the smaller ion traps will be discussed. The potential for highly charged ions will be briefly mentioned. (orig.)

  19. LASL high-current proton storage rings

    International Nuclear Information System (INIS)

    Lawrence, G.P.; Cooper, R.K.; Hudgings, D.W.; Spalek, G.; Jason, A.J.; Higgins, E.F.; Gillis, R.E.

    1980-01-01

    The Proton Storage Ring at LAMPF is a high-current accumulator designed to convert long 800-MeV linac pulses into very short high-intensity proton bunches ideally suited to driving a pulsed polyenergetic neutron source. The Ring, authorized for construction at $19 million, will operate in a short-bunch high-frequency mode for fast neutron physics and a long-bunch low-frequency mode for thermal neutron-scattering programs. Unique features of the project include charge-changing injection with initial conversion from H - to H 0 , a high repetition rate fast-risetime extraction kicker, and high-frequency and first-harmonic bunching system

  20. Generation of intense, high-energy ion pulses by magnetic compression of ion rings

    International Nuclear Information System (INIS)

    Kapetanakos, C.A.

    1981-01-01

    A system based on the magnetic compression of ion rings, for generating intense (High-current), high-energy ion pulses that are guided to a target without a metallic wall or an applied external magnetic field includes a vacuum chamber; an inverse reflex tetrode for producing a hollow ion beam within the chamber; magnetic coils for producing a magnetic field, bo, along the axis of the chamber; a disc that sharpens a magnetic cusp for providing a rotational velocity to the beam and causing the beam to rotate; first and second gate coils for producing fast-rising magnetic field gates, the gates being spaced apart, each gate modifying a corresponding magnetic mirror peak (Near and far peaks) for trapping or extracting the ions from the magnetic mirror, the ions forming a ring or layer having rotational energy; a metal liner for generating by magnetic flux compression a high, time-varying magnetic field, the time-varying magnetic field progressively increasing the kinetic energy of the ions, the magnetic field from the second gate coil decreasing the far mirror peak at the end of the compression for extracting the trapped rotating ions from the confining mirror; and a disc that sharpens a magnetic half-cusp for increasing the translational velocity of the ion beam. The system utilizes the self-magnetic field of the rotating, propagating ion beam to prevent the beam from expanding radially upon extraction

  1. High current density ion source

    International Nuclear Information System (INIS)

    King, H.J.

    1977-01-01

    A high-current-density ion source with high total current is achieved by individually directing the beamlets from an electron bombardment ion source through screen and accelerator electrodes. The openings in these screen and accelerator electrodes are oriented and positioned to direct the individual beamlets substantially toward a focus point. 3 figures, 1 table

  2. Generation of stable mixed-compact-toroid rings by inducing plasma currents in strong E rings

    International Nuclear Information System (INIS)

    Jayakumar, R.; Taggart, D.P.; Parker, M.R.; Fleischmann, H.H.

    1989-01-01

    In the RECE-Christa device, hybrid-type compact toroid rings are generated by inducing large toroidal plasma currents I rho in strong electron rings using a thin induction coil positioned along the ring axis. Starting from field-reversal values δ ο = 50 - 120 percent of the original pure fast-electron ring, the induced plasma current I rho raises δ to a maximum value of up to 240 percent with I rho contributing more than 50 percent of the total ring current. Quite interestingly, the generated hybrid compact toroid configurations appear gross-stable during the full I rho pulse length (half-amplitude width about 100 μs)

  3. Enabling Ring-Cusp Ion Thruster Technology for NASA Missions

    Data.gov (United States)

    National Aeronautics and Space Administration — ESA is flying T6 Kaufman ion thrusters on the BepiColombo Mission to Mercury in 2018. They are planning to develop a longer life, higher performing, 30-cm ring-cusp...

  4. The earth's ring current - Present situation and future thrusts

    Science.gov (United States)

    Williams, D. J.

    1987-01-01

    Particle distributions, currents, and the ring current situation prior to the August 1984 launch of the AMPTE Charge Composition Explorer (CCE) are discussed. CCE results which demonstrate the capability of these new measurements to pursue questions of ring current sources, energization, and transport are presented. Consideration is given to various ring current generation mechanisms which have been discussed in the literature, and a two-step generation process which to a certain extent unifies the previous mechanisms is presented. The first in-situ global observations of ring current decay as obtained through the detection of energetic neutral atoms generated by charge exchange interactions between the ring current and hydrogen geocorona are discussed, as well as the possibility of using the detection of energetic neutral atoms to obtain global images of the earth's ring current.

  5. Study of the energy spectra of the major ion species in the ring-current region of the magnetosphere during geomagnetic storms

    International Nuclear Information System (INIS)

    Kistler, L.M.

    1987-01-01

    Using the University of Maryland/Max Planck Institute for Aeronomy Charge Energy Mass (CHEM) spectrometer on the AMPTE Charge Composition Explorer (CCE) spacecraft, the author examined the near-equatorial storm-time energy spectra of four major magnetospheric ions, H + , O + , He + , and He ++ over the energy range 1-300 keV/e in the L-range 3-6. The data were obtained during the main phase of all geomagnetic storms with minimum Dst less than -50 in the time period September 1984 to November 1985. During this period, the orbit of the CCE precessed such that the full range of local times was covered. When the spectra are organized by local time, certain features emerge. In particular, there is a dip in the spectra of all ions at 10-20 keV/e in the drawn-to-noon sector, while in the noon-to-dusk sector the proton distribution function drops off sharply below ∼5 keV. These spectra were compared with those predicted by a model of ion drift and loss in the magnetosphere. It was found that the spectra are most consistent with a Volland-Stern electric field with γ = 2 and with a rotation of the nominal dawn-to-dusk electric field eastward by two hours local time

  6. Injection, compression and stability of intense ion-rings

    International Nuclear Information System (INIS)

    Sudan, R.N.

    1975-01-01

    Recent advances in pulsed high power ion beam technology make possible the creation of intense ion-rings with strong self-magnetic fields by single pulse injection. Such ion rings have several uses in controlled fusion e.g., to produce a min parallel B parallel magnetic geometry with a mirror ratio much higher than is possible with external conductors. For even stronger ion rings a min parallel B parallel with closed lines of force (ASTRON type) can be created. For this purpose, since the ion energies required are much higher than are available from high power sources, magnetic compression can be utilized to increase the ion energy. The success of this scheme depends critically on the stability of the ion ring. The low frequency perturbations of the ring-plasma system is examined by means of a generalization of the energy principle which established sufficient conditions for stability. The high-frequency micro-instabilities and their nonlinear consequences are discussed in terms of conventional techniques

  7. Ion effects in the SLC electron damping ring under exceptionally poor vacuum conditions

    International Nuclear Information System (INIS)

    Zimmermann, F.; Krejcik, P.; Minty, M.; Pritzkau, D.; Raubenheimer, T.; Ross, M.; Woodley, M.

    1997-10-01

    In 1996, due to a catastrophic kicker chamber failure in the SLC electron damping ring, the ring vacuum system was contamianted for several months. During this time, the vertical emittance of the beam extracted from the ring was increased by a large factor (4--20). The emittance slowly decreased as the vacuum pressure gradually improved. At the same time, an intermittent vertical instability was observed. Both the emittance blow-up and the instability behavior depended strongly on beam current, ring pressure, number of bunches in the ring (1 or 2), duty cycle, store time and betatron tunes. In this report, the authors describe the observations, and compare them with predictions from classical ion-trapping and ion-instability theories

  8. Laser-Cooled Ions and Atoms in a Storage Ring

    International Nuclear Information System (INIS)

    Kleinert, J.; Hannemann, S.; Eike, B.; Eisenbarth, U.; Grieser, M.; Grimm, R.; Gwinner, G.; Karpuk, S.; Saathoff, G.; Schramm, U.; Schwalm, D.; Weidemueller, M.

    2003-01-01

    We review recent experiments at the Heidelberg Test Storage Ring which apply advanced laser cooling techniques to stored ion beams. Very high phase-space densities are achieved by three-dimensional laser cooling of a coasting 9 Be + beam at 7.3 MeV. Laser-cooled, trapped Cs atoms are used as an ultracold precision target for the study of ion-atom interactions with a 74 MeV beam of 12 C 6+ ions.

  9. Present status of the ion ring compressor approach to fusion

    International Nuclear Information System (INIS)

    Fleischmann, H.H.

    1975-01-01

    A short review is given of the present research status with regard to the Ion Ring Compressor. A consideration of the reactor characteristics of this fusion scheme indicates the potential for a number of technologically and economically interesting features, in particular with respect to the high-confinement characteristics expected for such minimum-B configurations. Experimental results from the RECE-program at Cornell indicate generally good gross stability of strong electron rings, including purely collisional decay, stability against field perturbations and others. Most-recent experiments have extended the ring lifetime to more than 2 x 10 5 electron orbits. Strong electron rings have been shifted over an axial distance of up to 30 cm. Experiments with magnetic-field insulated diodes indicate ion pulses of up to 300 nsec, and field insulation of up to 800 nsec when metallic electrodes are used

  10. Atomic and molecular physics with ion storage rings

    International Nuclear Information System (INIS)

    Larsson, M.

    1995-01-01

    Advances in ion-source, accelerator and beam-cooling technology have made it possible to produce high-quality beams of atomic ions in arbitrary charged states as well as molecular and cluster ions are internally cold. Ion beams of low emittance and narrow momentum spread are obtained in a new generation of ion storage-cooler rings dedicated to atomic and molecular physics. The long storage times (∼ 5 s ≤ τ ≤ days) allow the study of very slow processes occurring in charged (positive and negative) atoms, molecules and clusters. Interactions of ions with electrons and/or photons can be studied by merging the stored ion beam with electron and laser beams. The physics of storage rings spans particles having a charge-to-mass ratio ranging from 60 + and C 70 + ) to 0.4 - 1.0 (H + , D + , He 2+ , ..., U 92+ ) and collision processes ranging from <1 meV to ∼ 70 GeV. It incorporates, in addition to atomic and molecular physics, tests of fundamental physics theories and atomic physics bordering on nuclear and chemical physics. This exciting development concerning ion storage rings has taken place within the last five to six years. (author)

  11. Persistent currents in an ensemble of isolated mesoscopic rings

    International Nuclear Information System (INIS)

    Altland, A.; Iida, S.; Mueller-Groelling, A.; Weidenmueller, H.A.

    1992-01-01

    In this work, the authors calculate the persistent current induced at zero temperature by an external, constant, and homogeneous magnetic field in an ensemble of isolated mesoscopic rings. In each ring, the electrons are assumed to move independently under the influence of a Gaussian white noise random impurity potential. They account for the magnetic field only in terms of the flux threading each ring, without considering the field present in the body of the ring. Particular attention is paid to the constraint of integer particle number on each ring. The authors evaluate the persistent current non-perturbatively, using a generating functional involving Grassmann integration. The magnetic flux threading each ring breaks the orthogonal symmetry of the formalism; forcing us to calculate explicitly the orthogonal-unitary crossover. 24 refs., 1 fig

  12. Ion trapping in the high-energy storage ring HESR

    Energy Technology Data Exchange (ETDEWEB)

    Hinterberger, Frank [Bonn Univ. (Germany). Helmholtz-Institut fuer Strahlen- und Kernphysik

    2011-10-15

    The problem of ion trapping in the high-energy storage ring HESR is studied in the present report. Positive ions are trapped in the negative potential well of the antiproton beam. The ions are produced by the interaction between the antiproton beam and the residual gas. The adverse effects of ion trapping like tune shifts, tune spreads and coherent instabilities are reviewed. The ion production rate by ionization of the residual gas molecules is estimated. The negative potential well and the corresponding electric fields of the antiproton beam are evaluated in order to study the transverse and longitudinal motion of the ions and the accumulation in trapping pockets. The removal of ions can be achieved using clearing electrodes and under certain conditions resonant transverse beam shaking. Diagnostic tools and measurements of trapped ion effects are sketched. (orig.)

  13. Device for monitoring electron-ion ring parameters

    International Nuclear Information System (INIS)

    Tyutyunnikov, S.I.; Shalyapin, V.N.

    1982-01-01

    The invention is classified as the method of collective ion acceleration. The device for electron-ion ring parameters monitoring is described. The invention is aimed at increasing functional possibilities of the device at the expense of the enchance in the number of the ring controlled parameters. The device comprises three similar plane mirrors installed over accelerating tube circumference and a mirror manufactured in the form of prism and located in the tube centre, as well as the system of synchrotron radiation recording and processing. Two plane mirrors are installed at an angle of 45 deg to the vertical axis. The angle of the third plane mirror 3 α and that of prismatic mirror 2 α to the vertical axis depend on geometric parameters of the ring and accelerating tube and they are determined by the expression α=arc sin R K /2(R T -L), where R K - ring radius, R T - accelerating tube radius, L - the height of segment, formed by the mirror and inner surface of the accelerating tube. The device suggested permits to determine longitudinal dimensions of the ring, its velocity and the number of electrons and ions in the ring

  14. Fano resonance and persistent current of a quantum ring

    International Nuclear Information System (INIS)

    Xiong Yongjian; Liang Xianting

    2004-01-01

    We investigate electron transport and persistent current of a quantum ring weakly attached to current leads. Assuming there is direct coupling (weakly or strongly) between two leads, electrons can transmit by the inter-lead coupling or tunneling through the quantum ring. The interference between the two paths yields asymmetric Fano line shape for conductance. In presence of interior magnetic flux, there is persistent current along the ring with narrow resonance peaks. The positions of the conductance resonances and the persistent current peaks correspond to the quasibound levels of the closed ring. This feature is helpful to determine the energy spectrum of the quantum ring. Our results show that the proposed setup provides a tunable Fano system

  15. A radio frequency ring electrode cooler for low-energy ion beams

    International Nuclear Information System (INIS)

    Heinz, S.; Aeystoe, J.; Habs, D.; Hegewisch, S.; Huikari, J.; Nieminen, A.; Rinta-Antila, S.; Schumann, M.; Szerypo, J.

    2004-01-01

    We are investigating a new concept for ion confinement while buffer-gas-cooling low-energy ion beams. Instead of applying the well-established technique of Radio Frequency Quadrupoles (RFQs) where the ions are transversely confined by a quadratic-pseudo potential we are using a stack of thin ring electrodes supplied by an RF field (RF funnel) which creates a box-shaped potential well. In Monte Carlo simulations we have investigated the transmission behavior and cooling performance of the RF funnel. First experimental investigations with ion currents up to 20 nA revealed a promising transmission characteristic which qualifies the RF funnel as high-current cooler

  16. Development of RF-linac and storage ring system for high-current experiments at GSI

    International Nuclear Information System (INIS)

    Hofmann, I.

    1986-08-01

    The heavy ion facility under construction at GSI is suitable for the generation of high-current beams. It consists of a new high-current injector into the Unilac and a synchrotron and storage ring. We discuss the capability of this system to produce short pulses of heavy ions with a specific energy of the order of 0.1 MJ/g. Under these conditions the system allows to perform a first generation of heavy ion driven target experiments and to test most of the critical issues of a large scale heavy ion fusion driver facility. (orig.)

  17. Topological ring currents in the "empty" ring of benzo-annelated perylenes.

    Science.gov (United States)

    Dickens, Timothy K; Mallion, Roger B

    2011-01-27

    Cyclic conjugation in benzo-annelated perylenes is examined by means of the topological π-electron ring currents calculated for each of their constituent rings, in a study that is an exact analogy of a recent investigation by Gutman et al. based on energy-effect values for the corresponding rings in each of these structures. "Classical" approaches, such as Kekulé structures, Clar "sextet" formulas, and circuits of conjugation, predict that the central ring in perylene is "empty" and thus contributes negligibly to cyclic conjugation. However, conclusions from the present calculations of topological ring currents agree remarkably with those arising from the earlier study involving energy-effect values in that, contrary to what would be predicted from the classical approaches, rings annelated in an angular fashion relative to the central ring of these perylene structures materially increase the extent of that ring's involvement in cyclic conjugation. It is suggested that such close quantitative agreement between the predictions of these two superficially very different indices (energy effect and topological ring current) might be due to the fact that, ultimately, both depend, albeit in ostensibly quite different ways, only on an adjacency matrix that contains information about the carbon-carbon connectivity of the conjugated system in question.

  18. ION EFFECTS IN THE APS PARTICLE ACCUMULATOR RING

    Energy Technology Data Exchange (ETDEWEB)

    Calvey, J.; Harkay, K.; Yao, CY.

    2017-06-25

    Trapped ions in the APS Particle Accumulator Ring (PAR) lead to a positive coherent tune shift in both planes, which increases along the PAR cycle as more ions accumulate. This effect has been studied using an ion simulation code developed at SLAC. After modifying the code to include a realistic vacuum profile, multiple ionization, and the effect of shaking the beam to measure the tune, the simulation agrees well with our measurements. This code has also been used to evaluate the possibility of ion instabilities at the high bunch charge needed for the APS-Upgrade.

  19. Measuring the electron-ion ring parameters by bremsstrahlung

    International Nuclear Information System (INIS)

    Inkin, V.D.; Mozelev, A.A.; Sarantsev, V.P.

    1982-01-01

    A system is described for measuring the number of electrons and ions in the electron-ion rings of a collective heavy ion accelerator. The system operation is based on detecting gamma quanta of bremsstrahlung following the ring electron interaction with the nuclei of neutral atoms and ions at different stages of filling the ring with ions. The radiation detector is a scintillation block - a photomultiplier operating for counting with NaI(Tl) crystal sized 30x30 mm and ensuring the detection efficiency close to unity. The system apparatus is made in the CAMAC standard and rems on-line with the TRA/i miniature computer. The block-diagrams of the system and algorithm of data processing are presented. A conclusion is drawn that the results of measuring the ring parameters with the use of the diagnostics system described are in good agreement within the range of measuring errors with those obtained by means of the diagnostics system employing synchrotron radiation and induction sensors

  20. Low energy current accumulator for high-energy proton rings

    International Nuclear Information System (INIS)

    Month, M.

    1977-01-01

    Building current in high-energy p-p colliding beam machines is most appropriately done in a low-energy (small circumference) current accumulator. Three significant factors favor such a procedure: First, large rings tend to be susceptible to unstable longitudinal density oscillations. These can be avoided by pumping up the beam in the accumulator. When the current stack is injected into the storage ring, potentially harmful instability is essentially neutralized. Second, high-field magnets characteristic of future high energy proton rings are designed with superconducting coils within the iron magnetic shield. This means coil construction and placement errors propagate rapidly within the beam aperture. An intermediate ''stacking ring'' allows the minimum use of the superconducting ring aperture. Finally, the coils are vulnerable to radiation heating and possible magnet quenching. By minimizing beam manipulaion in the superconducting environment and using only the central portion of the beam aperture, coil vulnerability can be put at a minimum

  1. The role of ring current O+ in the formation of stable auroral red arcs

    International Nuclear Information System (INIS)

    Kozyra, J.U.; Cravens, T.E.; Nagy, A.F.; Shelley, E.G.; Comfort, R.H.; Brace, L.H.

    1987-01-01

    Coulomb collisions between ring current protons and thermal electrons were first proposed by Cole (1965) as the energy source for stable auroral red (SAR) arcs. Recent observations have shown that the ring current and magnetospheric plasma contain significant amounts of heavy ions (Johnson et al., 1977; Young et al., 1977; Geiss et al., 1978; and others). In fact, the ring current is often dominated by heavy ions at those energies (E ≤ 17 keV) important for Coulomb collisions on SAR arc field lines (Kozyra et al., 1986a). Observations (during four SAR arcs in 1981) of thermal and energetic ion populations by the Dynamics Explorer 1 satellite in the magnetospheric energy source region and nearly simultaneous Langmuir probe measurements of enhanced electron temperatures by Dynamics Explorer 2 within the SAR arc at F region heights have allowed the authors to examine the role of heavy ions in the formation of SAR arcs. They find that (1) sufficient energy is transferred to the electron gas at high altitudes via Coulomb collisions between the observed ring current ions and thermal electrons to support the enhanced (SAR arc) F region electron temperatures measured on these field lines, (2) the latitudinal variation in the electron heating rates calculated using observed ion populations is consistent with the observed variation in electron temperature across the SAR arc, and (3) in all cases, ring current O + is the major source of energy for the SAR arcs. This implies a relationship between the heavy ion content of the magnetospheric plasma and the occurrence frequency and intensity of SAR arcs

  2. Numerical simulation of injection and resistive trapping of ion rings

    International Nuclear Information System (INIS)

    Mankofsky, A.; Friedman, A.; Sudan, R.N.

    1981-01-01

    Numerical studies of the injection and resistive trapping efficiency of ion rings, using an improved algorithm are presented. Trapping efficiency is found to be strongly dependent upon the number of particles injected and upon mirror ratios in the system. Wall resistivity and beam divergence affect the process to a lesser extent. (author)

  3. Ionic ring current during magnetic disturbances according to observations at geostationary orbit

    International Nuclear Information System (INIS)

    Vlasova, N.A.; Kovtyukh, A.S.; Panasyuk, M.I.; Sosnovets, Eh.N.; Grafodanskij, O.S.; Islyaev, Sh.N.; Kozlov, A.G.

    1988-01-01

    Experimental data on variations of H + , (N,O) 2+ and (C,N,O) 4+ flows acquired at communication geostationary satellite GORIZONT (1985-07A) during and after weak magnetic disturbances (with amplitudes of D st -variations which are less than a few tens of nT) are analyzed. Dynamics of ion relative content is investigated. Change of ring current ionic composition within ∼ 50-120 keV/c energy range characterized by the increase of relative content of heavy ions of both solar and ionospheric origin was observed after two weak geomagnetic disturbances on 19-20.02 and 07.03.1985. Examples of disturbances where H + ions and (N,O) 2+ ionospheric ions are the main components of the injected ring current are presented along with the disturbances of such type

  4. On the propagation and decay of North Brazil Current rings

    Science.gov (United States)

    Jochumsen, Kerstin; Rhein, Monika; Hüttl-Kabus, Sabine; BöNing, Claus W.

    2010-10-01

    Near the western boundary of the tropical North Atlantic, where the North Brazil Current (NBC) retroflects into the North Equatorial Countercurrent, large anticyclonic rings are shed. After separating from the retroflection region, the so-called NBC rings travel northwestward along the Brazilian coast, until they reach the island chain of the Lesser Antilles and disintegrate. These rings contribute substantially to the upper limb return flow of the Atlantic Meridional Overturning Circulation by carrying South Atlantic Water into the northern subtropical gyre. Their relevance for the northward transport of South Atlantic Water depends on the frequency of their generation as well as on their horizontal and vertical structure. The ring shedding and propagation and the complex interaction of the rings with the Lesser Antilles are investigated in the ? Family of Linked Atlantic Model Experiments (FLAME) model. The ring properties simulated in FLAME reach the upper limit of the observed rings in diameter and agree with recent observations on seasonal variability, which indicates a maximum shedding during the first half of the year. When the rings reach the shallow topography of the Lesser Antilles, they are trapped by the island triangle of St. Lucia, Barbados and Tobago and interact with the island chain. The model provides a resolution that is capable of resolving the complex topographic conditions at the islands and illuminates various possible fates for the water contained in the rings. It also reproduces laboratory experiments that indicate that both cyclones and anticyclones are formed after a ring passes through a topographic gap. Trajectories of artificial floats, which were inserted into the modeled velocity field, are used to investigate the pathways of the ring cores and their fate after they encounter the Lesser Antilles. The majority of the floats entered the Caribbean, while the northward Atlantic pathway was found to be of minor importance. No prominent

  5. Stability of large orbit, high-current particle rings

    International Nuclear Information System (INIS)

    Lovelace, R.V.E.

    1994-01-01

    A review is made of theory of the low-frequency stability of large orbit, high-current particle rings which continue to be of interest for compact fusion systems. The precession mode was the first mode predicted by Furth and observed by Christofilos to be unstable under certain conditions. Subsequently, many detailed studies have been made of the stability of particle rings- different modes, different ring geometries, systems with/without a toroidal B field, and sytems with/without a current carrying plasma component. The possibly dangerous modes are still thought to include the precession mode, the tilting mode, and the low order kink modes. copyright American Institute of Physics

  6. Tilt stability of rotating current rings with passive conductors

    International Nuclear Information System (INIS)

    Zweibel, E.G.; Pomphrey, N.

    1984-12-01

    We study the combined effects of rotation and resistive passive conductors on the stability of a rigid current in an external magnetic field. We present numerical and approximate analytical solutions to the equations of motion, which show that the ring is always tilt unstable on the resistive decay timescale of the conductors, although rotation and eddy currents may stabilize it over short times. Possible applications of our model include spheromaks which rotate or which are encircled by energetic particle rings

  7. Theory of magnetospheric hydromagnetic waves excited by energetic ring-current protons

    International Nuclear Information System (INIS)

    Chen, Liu; Hasegawa, Akira.

    1987-06-01

    A general theoretical formulation, allowing finite ion Larmor radii, general magnetic field geometries and plasma equilibria, has been developed to investigate excitations of magnetohydrodynamic (MHD) Alfven waves within the earth's magnetosphere by the storm-time energetic ring-current protons. In particular, it is found that for adiabatically injected protons, various predicted instability properties are consistent with satellite observations. 8 refs

  8. Laser-Cooled Ions and Atoms in a Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Kleinert, J.; Hannemann, S.; Eike, B.; Eisenbarth, U.; Grieser, M.; Grimm, R.; Gwinner, G.; Karpuk, S.; Saathoff, G.; Schramm, U.; Schwalm, D.; Weidemueller, M., E-mail: m.weidemueller@mpi-hd.mpg.de [Max-Planck-Insitut fuer Kernphysik (Germany)

    2003-03-15

    We review recent experiments at the Heidelberg Test Storage Ring which apply advanced laser cooling techniques to stored ion beams. Very high phase-space densities are achieved by three-dimensional laser cooling of a coasting {sup 9}Be{sup +} beam at 7.3 MeV. Laser-cooled, trapped Cs atoms are used as an ultracold precision target for the study of ion-atom interactions with a 74 MeV beam of {sup 12}C{sup 6+} ions.

  9. Dissociative recombination and excitation in ion storage rings

    International Nuclear Information System (INIS)

    Larsson, Mats

    2000-01-01

    The application of ion storage rings to the study of electron-molecular ion interaction has led to an experimental breakthrough. The development since the first experiments with molecular ions in storage rings about seven years ago, which in themselves represented a big leap forward, has been striking, and was impossible to envision at the outset. The development has been driven by advances in accelerator physics, detector technology, challenging applications in astrophysics and atmospheric physics, and by a close interplay with theory. Despite the remarkable progress, many important questions remain unanswered. For example, even for someone with a good knowledge of molecular physics it may come as a surprise that it is far from understood how the simplest polyatomic molecule H 3 + recombines with electrons, and it remains an experimental controversy at what rate it recombines

  10. Sources and sinks of Earth's ring current populations

    Science.gov (United States)

    Mauk, B.

    2017-12-01

    Processes that modify and transport current-carrying particles into and out of Earth's ring current regions are overviewed and discussed here with a focus on outstanding mysteries and uncertainties. Examples of such mysteries include the following. Some modeling and observational approaches point to a need for storm-time enhancements in the global electric field configuration to help bring magnetotail populations into the inner magnetosphere. And yet, electric field measurements from several missions, most recently the Van Allen Probes, suggest that only highly transient enhancements occur in critical regions that connect the outer and inner regions. Global enhancements appear to be internally generated rather than necessarily being driven from the outside. Another sample mystery involves the processes that give rise to the sometimes initial prompt recovery of the magnetic storm indice DST, given that loss processes traditionally invoked are likely too slow. Wave losses, such as those engendered by Electromagnetic Ion Cyclotron (EMIC) waves, may be responsible, but observational support for such a solution is lacking. These and other uncertainties are discussed with a goal of addressing how they might be addressed with the present great constellation of Earth-orbiting spacecraft, most recently joined by MMS and Arase (ERG).

  11. Effects of substorms on the stormtime ring current index Dst

    Directory of Open Access Journals (Sweden)

    G. Rostoker

    2000-11-01

    Full Text Available There has been some discussion in recent times regarding whether or not substorm expansive phase activity plays any role of importance in the formation of the stormtime ring current. I explore this question using the Kp index as a proxy for substorm expansive phase activity and the Dst index as a proxy for symmetric ring current strength. I find that increases in Dst are mildly related to the strength of substorm expansive phase activity during the development of the storm main phase. More surprisingly, I find that the strength of Dst during the storm recovery phase is positively correlated with the strength of substorm expansive phase activity. This result has an important bearing on the question of how much the Dst index reflects activity other than that of the stormtime symmetric ring current strength for which it is supposed to be a proxy.Key words: Ionosphere (electric fields and currents - Magnetospheric physics (current systems; storms and substorms

  12. Effects of substorms on the stormtime ring current index Dst

    Directory of Open Access Journals (Sweden)

    G. Rostoker

    Full Text Available There has been some discussion in recent times regarding whether or not substorm expansive phase activity plays any role of importance in the formation of the stormtime ring current. I explore this question using the Kp index as a proxy for substorm expansive phase activity and the Dst index as a proxy for symmetric ring current strength. I find that increases in Dst are mildly related to the strength of substorm expansive phase activity during the development of the storm main phase. More surprisingly, I find that the strength of Dst during the storm recovery phase is positively correlated with the strength of substorm expansive phase activity. This result has an important bearing on the question of how much the Dst index reflects activity other than that of the stormtime symmetric ring current strength for which it is supposed to be a proxy.Key words: Ionosphere (electric fields and currents - Magnetospheric physics (current systems; storms and substorms

  13. Energy content of stormtime ring current from phase space mapping simulations

    International Nuclear Information System (INIS)

    Chen, M.W.; Schulz, M.; Lyons, L.R.

    1993-01-01

    The authors perform a model study to account for the increase in energy content of the trapped-particle population which occurs during the main phase of major geomagnetic storms. They consider stormtime particle transport in the equatorial region of the magnetosphere. They start with a phase space distribution of the ring current before the storm, created by a steady state transport model. They then use a previously developed guiding center particle simulation to map the stormtime ring current phase space, following Liouville's theorem. This model is able to account for the ten to twenty fold increase in energy content of magnetospheric ions during the storm

  14. Multiple Coulomb ordered strings of ions in a storage ring

    International Nuclear Information System (INIS)

    Hasse, Rainer W.

    2002-01-01

    We explain that the anomalous frequency shifts of very close masses measured in the high precision mass measurement experiments in the ESR storage ring result from the locking of Coulomb interacting strings of ions. Here two concentric strings which run horizontally close to each other for many revolutions are captured into a single string if their thermal clouds overlap. They give up their identity and lock into an average frequency

  15. Ion Demagnetization in the Magnetopause Current Layer Observed by MMS

    Science.gov (United States)

    Wang, Shan; Chen, Li-Jen; Hesse, Michael; Gershman, Daniel J.; Dorelli, John; Giles, Barbara; Torbert, Roy B.; Pollock, Craig J.; Lavraud, Benoit; Strangeway, Robert; hide

    2016-01-01

    We report ion velocity distribution functions (VDfs) observed by Magnetospheric Multiscale Mission (MMS) and present evidence for demagnetized ion Speiser motion during magnetopause reconnection. The demagnetization is observed in the vicinity of the X llne, as well as near the current sheet midlplane about tens of ion skin depths (d(sub 1)) away from the X line. Close to the X line before the outflow is built up, the VDFs are elongated, and the elongated part of VDFs rotates from the out-of-plane current direction toward the outflow directions downstream from the X line. Farther downstream, demagnetized ions exhibit a characteristic half-ring structure in the VDFs, as a result of the mixture of ions that have experienced different amounts of cyclotron turning around the magnetic field normal to the current sheet. Signatures of acceleration by electric fields are more pronounced in the VDFs near the X line than downstream.

  16. Four faces of the interaction between ions and aromatic rings.

    Science.gov (United States)

    Papp, Dóra; Rovó, Petra; Jákli, Imre; Császár, Attila G; Perczel, András

    2017-07-15

    Non-covalent interactions between ions and aromatic rings play an important role in the stabilization of macromolecular complexes; of particular interest are peptides and proteins containing aromatic side chains (Phe, Trp, and Tyr) interacting with negatively (Asp and Glu) and positively (Arg and Lys) charged amino acid residues. The structures of the ion-aromatic-ring complexes are the result of an interaction between the large quadrupole moment of the ring and the charge of the ion. Four attractive interaction types are proposed to be distinguished based on the position of the ion with respect to the plane of the ring: perpendicular cation-π (CP ⊥ ), co-planar cation-π (CP ∥ ), perpendicular anion-π (AP ⊥ ), and co-planar anion-π (AP ∥ ). To understand more than the basic features of these four interaction types, a systematic, high-level quantum chemical study is performed, using the X -  + C 6 H 6 , M +  + C 6 H 6 , X -  + C 6 F 6 , and M +  + C 6 F 6 model systems with X -  = H - , F - , Cl - , HCOO - , CH 3 COO - and M +  = H + , Li + , Na + , NH4+, CH 3 NH3+, whereby C 6 H 6 and C 6 F 6 represent an electron-rich and an electron-deficient π system, respectively. Benchmark-quality interaction energies with small uncertainties, obtained via the so-called focal-point analysis (FPA) technique, are reported for the four interaction types. The computations reveal that the interactions lead to significant stabilization, and that the interaction energy order, given in kcal mol -1 in parentheses, is CP ⊥ (23-37) > AP ⊥ (14-21) > CP ∥ (9-22) > AP ∥ (6-16). A natural bond orbital analysis performed leads to a deeper qualitative understanding of the four interaction types. To facilitate the future quantum chemical characterization of ion-aromatic-ring interactions in large biomolecules, the performance of three density functional theory methods, B3LYP, BHandHLYP, and M06-2X, is tested against the FPA benchmarks

  17. Current trends in ion implantation

    International Nuclear Information System (INIS)

    Gwilliam, R.M.

    2001-01-01

    As semiconductor device dimensions continue to shrink, the drive beyond 250 nm is creating significant problems for the device processor. In particular, trends toward shallower-junctions, lower thermal budgets and simplified processing steps present severe challenges to ion implantation. In parallel with greater control of the implant process goes the need for a better understanding of the physical processes involved during implantation and subsequent activation annealing. For instance, the need for an understanding of dopant-defect interaction is paramount as defects mediate a number of technologically important phenomena such as transient enhanced diffusion and impurity gettering. This paper will outline the current trends in the ion implantation and some of the challenges it faces in the next decade, as described in the semiconductor roadmap. It will highlight some recent positron annihilation work that has made a contribution to addressing one of these challenges, namely the need for tighter control of implant uniformity and dose. Additionally, some vacancy-mediated processes are described with the implication that these may provide areas in which positron annihilation spectroscopy could make a significant contribution. (orig.)

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

    Science.gov (United States)

    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.

  19. Storm-time ring current: model-dependent results

    Directory of Open Access Journals (Sweden)

    N. Yu. Ganushkina

    2012-01-01

    Full Text Available The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT on 6–7 November 1997 and one intense (SymH minimum of −230 nT on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM, in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.

  20. Astrochemistry in TSR and CSR Ion Storage Rings

    Science.gov (United States)

    Novotny, Oldrich

    2017-04-01

    Dissociative recombination (DR) of molecular ions plays a key role in controlling the charge density and composition of the cold interstellar medium (ISM). Experimental data on DR are required in order to understand the chemical network in the ISM and related processes such as star formation from molecular clouds. Needed data include not only total reaction cross sections, but also the chemical composition and excitation states of the neutral products. Utilizing the TSR storage ring in Heidelberg, Germany, we have carried out DR measurements for astrophysically important molecular ions. We use a merged electron-ion beams technique combined with event-by-event fragment counting and fragment imaging. The count rate of detected neutral DR products yields the absolute DR rate coefficient. Imaging the distribution of fragment distances provides information on the kinetic energy released including the states of both the initial molecule and the final products. Additional kinetic energy sensitivity of the employed detector allows for identification of fragmentation channels by fragment-mass combination within each dissociation event. Such combined information is essential for studies on DR of polyatomic ions with multi-channel breakup. The recently commissioned Cryogenic Storage Ring (CSR) in Heidelberg, Germany, extends the experimental capabilities of TSR by operation at cryogenic temperatures down to 6 K. At these conditions residual gas densities down to 100 cm-3 can be reached resulting in beam storage times of several hours. Long storage in the cold environment allows the ions to relax down to their rotational ground state, thus mimicking well the conditions in the cold ISM. A variety of astrophysically relevant reactions will be investigated at these conditions, such as DR, electron impact excitation, ion-neutral collisions, etc. We report our TSR results on DR of HCl+ and D2Cl+. We also present first results from the CSR commissioning experiments.

  1. New Way of Characterizing the State of the Ring Current

    Science.gov (United States)

    Wolf, R.; Bao, S.; Gkioulidou, M.; Yang, J.; Toffoletto, F.

    2017-12-01

    The flux tube entropy S is invariant in ideal MHD and is a good way to characterize the degree to which a closed flux tube is loaded with particle energy. Flux tube entropy generally increases with increasing geocentric distance. A flux tube that is injected from the plasma sheet into the ring current tends to be a bubble that has a lower S value than typical plasma sheet flux tubes, and it tends to penetrate to a position where the surroundings matches its S. From this point of view, a good way to characterize the state of the ring current is through the function dF/dS, which specifies how much magnetic flux is occupied by tubes with different degrees of loading. By displaying dF/dS curves before and during storm main phases simulated with the RCM-E code, we determine that, in the model, the injection of the stormtime ring current consists of replacing pre-storm low-S flux tubes with tubes from the plasma sheet that have a certain limited range of S, which is well below typical plasma-sheet values. We also display dF/dS curves for passes by the Van Allen Probes before and during storm main phases, and compare with the RCM-E-derived curves, to gain insight into the nature of the flux tubes that are injected to form the real storm-time ring current.

  2. Oscillatory persistent currents in self-assembled quantum rings

    NARCIS (Netherlands)

    Kleemans, N.A.J.M.; Bominaar-Silkens, I.M.A.; Fomin, V.; Gladilin, V.N.; Granados, D.; Taboada, A.G.; Garcia, J.M.; Offermans, P.; Zeitler, U.; Christianen, P.C.M.; Maan, J.C.; Devreese, J.T.; Koenraad, P.M.

    2007-01-01

    We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural

  3. Radioactive Ions Production Ring for Beta-Beams

    CERN Document Server

    Benedetto, E; Wehner, J

    2010-01-01

    Within the FP7 EUROnu program, Work Package 4 addresses the issues of production and acceleration of 8Li and 8B isotopes through the Beta-Beam complex, for the production of electron-neutrino. One of the major critical issues is the production of a high enougth ion ßux, to fulÞll the requirements for physics. In alternative to the direct ISOL production method, a new ap- proach is proposed in [1]. The idea is to use a compact ring for Litium ions at 25 MeV and an internal He or D target, in which the radioactive-isotopes production takes place. The beam is expected to survive for several thousands of turns, therefore cooling in 6D is required and, according this scheme, the ionization cooling provided by the target itself and a suitable RF system would be sufÞcient. We present some preliminary work on the Production ring lat- tice design and cooling issues, for the 7Li ions, and propose plans for future studies, within the EUROnu program.

  4. Laser cooling and ion beam diagnosis of relativistic ions in a storage ring

    International Nuclear Information System (INIS)

    Schroeder, S.

    1990-08-01

    Particle accelerator and storage ring technology has reached an advanced state, so that different heavy ion storage rings are coming into operation by now, capable of storing even fully stripped ions up to U 92+ . The main purpose of these machines are the accumulation of ions and the ability of improving the beam quality, that is the phase space density of the stored beams. This beam cooling is done successfully by the well established stochastic and electron cooling techniques. A new cooling method, the laser cooling, is taken over from atomic beam and ion trap experiments, where it has yielded extremely low temperatures of atomic samples. As a canditate at storage rings 7 Li + ions are stored in the Heidelberg TSR at 13.3 MeV. The ion beam properties of the metastable fraction like momentum spread, storage time and the influence of residual gas scattering are investigated by colinear laser spectroscopy in the experimental section of the TSR. An optical pumping experiment using two dye laser systems yields information about ion kinematics and velocity mixing processes in the ring. Lifetimes in the order of 100 ms for velocity classes marked in this way show that laser cooling can be applied to the stored 7 Li + beam. In an experimental situation of two strong counterpropagating laser beams, both tuned near resonance, a dramatic reduction of the ion beam momentum spread is observed. With a special geometrical control of laser and ion beam the longitudinal beam temperature is reduced from 260 K to at least 3 K with very high collection efficiency. (orig./HSI) [de

  5. Persistent currents in metallic rings containing a quantum dot

    International Nuclear Information System (INIS)

    Machura, Lukasz; Łuczka, Jerzy

    2015-01-01

    Currents in metallic rings with a quantum dot are studied in the framework of a Langevin equation for a magnetic flux passing through the ring. Two scenarios are considered: one in which thermal fluctuations of the dissipative part of the current are modeled by classical Johnson–Nyquist noise and one in which quantum character of thermal fluctuations is taken into account in terms of a quantum Smoluchowski equation. The impact of the amplitude and phase of the transmission coefficient of the electron through a quantum dot on current characteristics is analyzed. In tailored parameter regimes, both scenarios can exhibit the transition from para- to diamagnetic response of the current versus external magnetic flux. The type of response is more robust to changes of the amplitude of the transmission coefficient and more sensitive to changes of the phase around some values. - Highlights: • Langevin dynamics of the magnetic flux for classical and quantum Smoluchowski regimes. • Current-flux characteristics vs the amplitude and phase of the transmission coefficient. • Crucial role of the phase of the transmission coefficient. • Contribution to the development of effective control of current in mesoscopic rings

  6. Electronic States and Persistent Currents in Nanowire Quantum Ring

    Science.gov (United States)

    Kokurin, I. A.

    2018-04-01

    The new model of a quantum ring (QR) defined inside a nanowire (NW) is proposed. The one-particle Hamiltonian for electron in [111]-oriented NW QR is constructed taking into account both Rashba and Dresselhaus spin-orbit coupling (SOC). The energy levels as a function of magnetic field are found using the exact numerical diagonalization. The persistent currents (both charge and spin) are calculated. The specificity of SOC and arising anticrossings in energy spectrum lead to unusual features in persistent current behavior. The variation of magnetic field or carrier concentration by means of gate can lead to pure spin persistent current with the charge current being zero.

  7. On the magnetic effect of the quiet ring current

    International Nuclear Information System (INIS)

    Feldstein, Ya.I.; Porchkhidze, Ts.D.

    1983-01-01

    Magnetic effects of the quiet ring current DRsu (q) along the geomagnetic equator near a minimUm of solar activity are considered. The division of Dsub(st)-variation of the geomagnetic field observed on the Earth's surface into DCF and DR components for January 23-24, 1974 has been carried out. DRsup(q) being 16.7 nT. A comparison with the magnetic field of the ring current and the energy particles moving round the Earth in the radiation zone shows a good agreement in the intensities obtained by two methods. This means that in calculating the Dsub(st)-index the values of the H-component of the field are taken as a bench mark during such time intervals when the DRsup(q) field is approximately compensated by the fields of currents on the magnetopause DCFsup(q). The estimates giVe RCsup(q) approximately - 12 nT

  8. Advances in electron cooling in heavy-ion storage rings

    International Nuclear Information System (INIS)

    Danared, H.

    1994-01-01

    The efficiency of electron cooling can be improved by reducing the temperature of the electrons. If the magnetic field at the location of the electron gun is stronger than in the region where the electrons interact with the ions, and the field gradient is adiabatic with respect to the cyclotron motion of the electrons, the resulting expansion of the electron beam reduces its transverse temperature by a factor equal to the ratio between the two fields. A ten times expanded electron beam was introduced in the CRYRING electron cooler in the summer of 1993, and similar arrangements have since then been made at the TSR ring in Heidelberg and at ASTRID in Aarhus. The reduction of the transverse electron temperature has increased cooling rates with large factors, and improves the energy resolution and increases count rates when the cooler is used as an electron target for ion-electron recombination experiments

  9. Numerical simulation of crystalline ion beams in storage ring

    CERN Document Server

    Meshkov, I N; Katayama, T; Sidorin, A; Smirnov, A Yu; Syresin, E M; Trubnikov, G; Tsutsui, H

    2004-01-01

    The use of crystalline ion beams can increase luminosity in the collider and in experiments with targets for investigation of rare radioactive isotopes. The ordered state of circulating ion beams was observed at several storage rings: NAP-M (Proceedings of the Fourth All Union Conference on Charged Particle Accelerators, Vol. 2, Nauka, Moscow, 1975 (in Russian); Part. Accel. 7 (1976) 197; At. Energy 40 (1976) 49; Preprint CERN/PS/AA 79-41, Geneva, 1979) (Novosibirsk), ESR (Phys. Rev. Lett. 77 (1996) 3803) and SIS (Proceedings of EPAC'2000, 2000) (Darmstadt), CRYRING (Proceedings of PAC'2001, 2001) (Stockholm) and PALLAS (Proceedings of the Conference on Applications of Accelerators in Research and Industry, AIP Conference Proceedings, p. 576, in preparation) (Munchen). New criteria of the beam orderliness are derived and verified with a new program code. Molecular dynamics technique is inserted in BETACOOL program (Proceedings of Beam Cooling and Related Topics, Bad Honnef, Germany, 2001) and used for numeric...

  10. A cryogenic current-measuring device with nano-ampere resolution at the storage ring TARN II

    International Nuclear Information System (INIS)

    Tanabe, T.; Chida, K.; Shinada, K.

    1999-01-01

    In cooler-ring experiments, an accurate and non-destructive current measurement is essential for determining the reaction cross sections. The lowest current which can be measured by the DC current transformer commonly used so far is some μA. In order to measure a low-beam current from nA to μA, we made a cryogenic current-measuring device using a superconducting quantum interference devices (SQUID), and measured the circulating ion current at the cooler ring TARN II. This paper gives the design and performance of the device

  11. Simple, high current, antimony ion source

    International Nuclear Information System (INIS)

    Sugiura, H.

    1979-01-01

    A simple metal ion source capable of producing a continuous, uncontaminated, high current beam of Sb ions is presented. It produced a total ion current of 200 μA at 1 kV extraction voltage. A discharge occurred in the source at a pressure of 6 x 10 -4 Torr. The ion current extracted from the source increased with the 3/2 power of the extraction voltage. The perveance of the source and ion density in the plasma were 8 x 10 -9 and 1.8 x 10 11 cm -3 , respectively

  12. Internal target effects in ion storage rings with beam cooling

    International Nuclear Information System (INIS)

    Gostishchev, Vitaly

    2008-06-01

    The accurate description of internal target effects is important for the prediction of operation conditions which are required for experiments in the planned storage rings of the FAIR facility. The BETACOOL code developed by the Dubna group has been used to evaluate beam dynamics in ion storage rings, where electron cooling in combination with an internal target is applied. Systematic benchmarking experiments of this code were carried out at the ESR storage ring at GSI. A mode with vanishing dispersion in the target position was applied to evaluate the influence of the dispersion function on the parameters when the target is heating the beam. The influence of the internal target on the beam parameters is demonstrated in the present work. A comparison of experimental results with simple models describing the energy loss of the beam particles in the target as well as with more sophisticated simulations with the BETACOOL code is given. In order to study the conditions which can be achieved in the proposed experiments the simulation results were quantitatively compared with experimental results and simulations for the ESR. The results of this comparison are discussed in the present thesis. BETACOOL simulations of target effects were performed for the NESR and the HESR of the future FAIR facility in order to predict the beam parameters for the planned experiments. (orig.)

  13. Internal target effects in ion storage rings with beam cooling

    Energy Technology Data Exchange (ETDEWEB)

    Gostishchev, Vitaly

    2008-06-15

    The accurate description of internal target effects is important for the prediction of operation conditions which are required for experiments in the planned storage rings of the FAIR facility. The BETACOOL code developed by the Dubna group has been used to evaluate beam dynamics in ion storage rings, where electron cooling in combination with an internal target is applied. Systematic benchmarking experiments of this code were carried out at the ESR storage ring at GSI. A mode with vanishing dispersion in the target position was applied to evaluate the influence of the dispersion function on the parameters when the target is heating the beam. The influence of the internal target on the beam parameters is demonstrated in the present work. A comparison of experimental results with simple models describing the energy loss of the beam particles in the target as well as with more sophisticated simulations with the BETACOOL code is given. In order to study the conditions which can be achieved in the proposed experiments the simulation results were quantitatively compared with experimental results and simulations for the ESR. The results of this comparison are discussed in the present thesis. BETACOOL simulations of target effects were performed for the NESR and the HESR of the future FAIR facility in order to predict the beam parameters for the planned experiments. (orig.)

  14. Electron cooling of PB$^{54+}$ ions in the low energy ion ring (LEIR)

    CERN Document Server

    Bosser, Jacques; Chanel, M; MacCaferri, R; Maury, S; Möhl, D; Molinari, G; Tranquille, G

    1998-01-01

    For the preparation of dense bunches of lead ions for the LHC, electron cooling will be essential for accumula tion in a storage ring at 4.2 MeV/u. Tests have been carried out on the LEAR ring (renamed LEIR for Low Energy Ion Ring) in order to determine the optimum parameters for a future state-of-the-art electron cooling device which would be able to cool linac pulses of lead ions in less than 100 ms. The experiments focused on the generation of a stable high intensity electron beam that is needed to free space in both longitudinal and transverse phase space for incoming pulses. Investigations on the ion beam lifetime in the presence of the electron beam and on the dependency of the cooling times on the optical settings of the storage ring will also be discussed. This paper concentrates on the cooling aspects with the multiturn injection, vacuum, and high intensity aspects discussed in a companion paper at this conference.

  15. Dielectronic recombination experiments with tungsten ions at the test storage ring and development of a single-particle detector at the cryogenic storage ring

    International Nuclear Information System (INIS)

    Spruck, Kaija

    2015-05-01

    This work is about electron-ion collision experiments at the ion storage rings of the Max Planck Institute for Nuclear Physics in Heidelberg. Absolute recombination rate coefficients of highly-charged tungsten ions featuring an open 4-f-shell structure have been measured at the heavy-ion storage ring TSR. The resulting plasma rate coefficients have been used to probe the significance of newly developed theoretical approaches. Plasma rate coefficients of highly-charged tungsten ions are in particular interesting for the development of plasma models for nuclear fusion reactors, since tungsten is a foreseeable impurity in the fusion plasma. In the relevant temperature range, the experimental results exceed the theoretical data used so far by up to a factor of 10, showing the need for more reliable theoretical calculations. Furthermore, based on the design of the detectors which have been used in the experiments at TSR, a movable single-particle detector for electron-ion recombination studies at the cryogenic storage ring CSR has been developed and installed within the scope of this work. The device has been designed specifically to meet the requirements of the CSR regarding low ion energies and cryogenic ambient temperature conditions. In a series of experiments, the detector was carefully characterised and successfully tested for its compatibility with these requirements. The detector was part of the infrastructure used for the room-temperature commissioning of CSR (2014) and is currently operated as a single-particle counter during the first cryogenic operation of CSR in 2015.

  16. Dielectronic recombination experiments with tungsten ions at the test storage ring and development of a single-particle detector at the cryogenic storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Spruck, Kaija

    2015-05-15

    This work is about electron-ion collision experiments at the ion storage rings of the Max Planck Institute for Nuclear Physics in Heidelberg. Absolute recombination rate coefficients of highly-charged tungsten ions featuring an open 4-f-shell structure have been measured at the heavy-ion storage ring TSR. The resulting plasma rate coefficients have been used to probe the significance of newly developed theoretical approaches. Plasma rate coefficients of highly-charged tungsten ions are in particular interesting for the development of plasma models for nuclear fusion reactors, since tungsten is a foreseeable impurity in the fusion plasma. In the relevant temperature range, the experimental results exceed the theoretical data used so far by up to a factor of 10, showing the need for more reliable theoretical calculations. Furthermore, based on the design of the detectors which have been used in the experiments at TSR, a movable single-particle detector for electron-ion recombination studies at the cryogenic storage ring CSR has been developed and installed within the scope of this work. The device has been designed specifically to meet the requirements of the CSR regarding low ion energies and cryogenic ambient temperature conditions. In a series of experiments, the detector was carefully characterised and successfully tested for its compatibility with these requirements. The detector was part of the infrastructure used for the room-temperature commissioning of CSR (2014) and is currently operated as a single-particle counter during the first cryogenic operation of CSR in 2015.

  17. Plasma position from ring current measurements in Extrap T1

    International Nuclear Information System (INIS)

    Brunsell, P.; Jin Li.

    1989-11-01

    The inductive coupling between the plasma and the four octupole field coils in the Extrap T1 device is utilized as a means of estimating the plasma position. The current in each octupole ring as well as the plasma current is measured by a Rogowski coil and the ring - plasma mutual inductance is then computed assuming axisymmetric plasma displacements. The obtained position is in agreement with internal magnetic probe measurements. The time - evolution of the plasma position for different external vertical and toroidal field strengths is studied. For the present discharge parameter a vertical field of about .008 T is found to give an almost radially stationary plasma. The results are compared with a simple equilibrium model

  18. Electric currents induced by twisted light in Quantum Rings.

    Science.gov (United States)

    Quinteiro, G F; Berakdar, J

    2009-10-26

    We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.

  19. Survey of Digital Feedback Systems in High Current Storage Rings

    International Nuclear Information System (INIS)

    Teytelman, Dmitry

    2003-01-01

    In the last decade demand for brightness in synchrotron light sources and luminosity in circular colliders led to construction of multiple high current storage rings. Many of these new machines require feedback systems to achieve design stored beam currents. In the same time frame the rapid advances in the technology of digital signal processing allowed the implementation of these complex feedback systems. In this paper I concentrate on three applications of feedback to storage rings: orbit control in light sources, coupled-bunch instability control, and low-level RF control. Each of these applications is challenging in areas of processing bandwidth, algorithm complexity, and control of time-varying beam and system dynamics. I will review existing implementations as well as comment on promising future directions

  20. Current status of ion source development

    International Nuclear Information System (INIS)

    Ishikawa, Junzo

    2001-01-01

    In this report, the current status of ion source development will be discussed. In September 2001, the 9th International Conference on Ion Sources (ICIS01) was held in Oakland, U.S.A. Referring the talks presented at ICIS01, recent topics in the ion source research fields will be described. (author)

  1. Ion exchange currents in vacuum accelerator tubes

    International Nuclear Information System (INIS)

    Eastham, D.A.; Thorn, R.

    1978-01-01

    Ion exchange currents (microdischarges) have been observed in short lengths of accelerator tube. The occurrence of these discharges can be related to the trajectories of ions in the tube. High-resolution mass spectra of the negative and positive ion components have been obtained. (author)

  2. Ion currents in diesel engines

    OpenAIRE

    Rao, Rahul

    2017-01-01

    This thesis documents an experimental and modelling investigation into ion formation in diesel engines, its uses in the field of engine performance and emissions prediction and the mechanisms by which these uses are made possible. Ion sensors have been employed in engines for a variety of purposes, including estimation of air-fuel ratio, start of combustion and in-cylinder pressure, detection of knock, misfire and combustion resonance, prediction of soot formation, and control of spark ...

  3. Surface ionization ion source with high current

    International Nuclear Information System (INIS)

    Fang Jinqing; Lin Zhizhou; Yu Lihua; Zhan Rongan; Huang Guojun; Wu Jianhua

    1986-04-01

    The working principle and structure of a surface ionization ion source with high current is described systematically. Some technological keypoints of the ion source are given in more detail, mainly including: choosing and shaping of the material of the surface ionizer, heating of the ionizer, distributing of working vapour on the ionizer surface, the flow control, the cooling problem at the non-ionization surface and the ion optics, etc. This ion source has been used since 1972 in the electromagnetic isotope separator with 180 deg angle. It is suitable for separating isotopes of alkali metals and rare earth metals. For instance, in the case of separating Rubidium, the maximum ion current of Rbsup(+) extracted from the ion source is about 120 mA, the maximum ion current accepted by the receiver is about 66 mA, the average ion current is more than 25 mA. The results show that our ion source have advantages of high ion current, good characteristics of focusing ion beam, working stability and structure reliability etc. It may be extended to other fields. Finally, some interesting phenomena in the experiment are disccused briefly. Some problems which should be investigated are further pointed out

  4. Ionic ring current during magnetic disturbances according to observations at a geostationary orbit

    International Nuclear Information System (INIS)

    Vlasova, N.A.; Kovtyuk, A.S.; Panasyuk, M.I.

    1987-01-01

    Experimental data on the measurements of H + and group (C, N, O) ion fluxes with different charges obtained using the ''Gorizont'' geostationary satellite (1985 - 07A) during three moderate magnetic disturbances with the amplitudes of D st -variations of several tens nT, have been analyzed. It is shown that during magnetic storms with clearly pronounced main phases a powerful injection of H + and (N, O) 2+ ion fluxes in the absence of noticeable increases in multicharge (C, N, O) ion fluxes with the energies of tens keV/e takes place. The resuts testify in favour of ionospheric plasma as the main source of ring current particles in the energy range. Indications that the filling of geostationary orbit with solar origin ions takes place at the recovery phase of a storm in nighttime hours are obtained

  5. Modelling of the ring current in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Giampieri

    2004-01-01

    Full Text Available The existence of a ring current inside Saturn's magnetosphere was first suggested by Smith et al. (1980 and Ness et al. (1981, 1982, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. Connerney et al. (1983 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects. Key words. Magnetospheric physics (current systems; planetary magnetospheres; plasma sheet

  6. Developments at an electrostatic cryogenic storage ring for electron-cooled keV energy ion beams

    International Nuclear Information System (INIS)

    Vogel, Stephen

    2016-01-01

    This work is devoted to final setup activities and the commissioning of an electrostatic cryogenic storage ring (CSR) at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. The first cryogenic operation of CSR in 2015 has been documented and characterized using a set of non-destructive beam diagnostic tools developed within this work. These are (1) the current pick-up system for the determination of the current of the stored ion beam and its velocity, (2) a position pick-up system for measuring the transverse position of the ion beam center at six symmetric locations of the storage ring circumference, and (3) a Schottky pick-up system for the monitoring of coasting ion beams. Despite the requirements imposed by the cryogenic operation, the developed diagnostic system demonstrated its full functionality. First characterizations of the storage ring properties and the performance of the diagnostic system are presented. Based on previous work, an electron cooling system for CSR has been developed and largely realized. With the implementation into CSR in 2016, the electron cooler will enhance the storage ring into a unique experimental facility for electron-ion collision studies. With this CSR is on the track to become the first cryogenic storage ring featuring actively cooled ion beams.

  7. Cryogenic current comparators for precise ion beam current measurements

    International Nuclear Information System (INIS)

    Kurian, Febin

    2015-01-01

    The planned Facility for Antiproton and Ion Research (FAIR) at GSI has to cope with a wide range of beam intensities in its high-energy beam transport systems and in the storage rings. To meet the requirements of a non-intercepting intensity measurement down to nA range, it is planned to install a number of Cryogenic Current Comparator (CCC) units at different locations in the FAIR beamlines. In this work, the first CCC system for intensity measurement of heavy ion beams, which was developed at GSI, was re-commissioned and upgraded to be used as a 'GSI - CCC prototype' for extensive optimization and development of an improved CCC for FAIR. After installation of a new SQUID sensor and related electronics, as well as implementation of improved data acquisition components, successful beam current measurements were performed at a SIS18 extraction line. The measured intensity values were compared with those of a Secondary Electron Monitor (SEM). Furthermore, the spill-structure of a slowly extracted beam was measured and analyzed, investigating its improvement due to bunching during the slow-extraction process. Due to the extreme sensitivity of the superconducting sensor, the determined intensity values as well as the adjustment of the system for optimal performance are strongly influenced by the numerous noise sources of the accelerators environment. For this reason, detailed studies of different effects caused by noise have been carried out, which are presented together with proposals to reduce them. Similarly, studies were performed to increase the dynamic range and overcome slew rate limitations, the results of which are illustrated and discussed as well. By combining the various optimizations and characterizations of the GSI CCC prototype with the experiences made during beam operation, criteria for a more efficient CCC System could be worked out, which are presented in this work. The details of this new design are worked out with respect to the

  8. High current vacuum arc ion source for heavy ion fusion

    International Nuclear Information System (INIS)

    Qi, N.; Schein, J.; Gensler, S.; Prasad, R.R.; Krishnan, M.; Brown, I.

    1999-01-01

    Heavy Ion fusion (HIF) is one of the approaches for the controlled thermonuclear power production. A source of heavy ions with charge states 1+ to 2+, in ∼0.5 A current beams with ∼20 micros pulse widths and ∼10 Hz repetition rates are required. Thermionic sources have been the workhorse for the HIF program to date, but suffer from sloe turn-on, heating problems for large areas, are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states, in short and long pulse bursts, with low emittance and high beam currents. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications is investigated. An existing ion source at LBNL was modified to produce ∼0.5 A, ∼60 keV Gd (A∼158) ion beams. The experimental effort concentrated on beam noise reduction, pulse-to-pulse reproducibility and achieving low beam emittance at 0.5 A ion current level. Details of the source development will be reported

  9. Versatile high current metal ion implantation facility

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1992-01-01

    A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. (orig)

  10. Emittance measurements in low energy ion storage rings

    Science.gov (United States)

    Hunt, J. R.; Carli, C.; Resta-López, J.; Welsch, C. P.

    2018-07-01

    The development of the next generation of ultra-low energy antiproton and ion facilities requires precise information about the beam emittance to guarantee optimum performance. In the Extra-Low ENergy Antiproton storage ring (ELENA) the transverse emittances will be measured by scraping. However, this diagnostic measurement faces several challenges: non-zero dispersion, non-Gaussian beam distributions due to effects of the electron cooler and various systematic errors such as closed orbit offsets and inaccurate rms momentum spread estimation. In addition, diffusion processes, such as intra-beam scattering might lead to emittance overestimates. Here, we present algorithms to efficiently address the emittance reconstruction in presence of the above effects, and present simulation results for the case of ELENA.

  11. Split ring resonator for the Argonne superconducting heavy ion booster

    International Nuclear Information System (INIS)

    Shepard, K.W.; Scheibelhut, C.H.; Benaroya, R.; Bollinger, L.M.

    1977-01-01

    A split-ring resonator for use in the ANL superconducting heavy-ion linac was constructed and is being tested. The electromagnetic characteristics of the 98-MHz device are the same as the unit described earlier, but the housing is formed of a new material consisting of niobium sheet explosively bonded to copper. The niobium provides the superconducting path and the copper conducts heat to a small area cooled by liquid helium. This arrangement greatly simplified the cryogenic system. Fabrication of the housing was relatively simple, with the result that costs have been reduced substantially. The mechanical stability of the resonator and the performance of the demountable superconducting joints are significantly better than for the earlier unit

  12. Split ring resonator for the Argonne superconducting heavy ion booster

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, K.W.; Scheibelhut, C.H.; Benaroya, R.; Bollinger, L.M.

    1977-01-01

    A split-ring resonator for use in the ANL superconducting heavy-ion linac was constructed and is being tested. The electromagnetic characteristics of the 98-MHz device are the same as the unit described earlier, but the housing is formed of a new material consisting of niobium sheet explosively bonded to copper. The niobium provides the superconducting path and the copper conducts heat to a small area cooled by liquid helium. This arrangement greatly simplified the cryogenic system. Fabrication of the housing was relatively simple, with the result that costs have been reduced substantially. The mechanical stability of the resonator and the performance of the demountable superconducting joints are significantly better than for the earlier unit.

  13. Development of a high current ion implanter

    International Nuclear Information System (INIS)

    Choi, Byung Ho; Kim, Wan; Jin, Jeong Tae

    1990-01-01

    A high current ion implanter of the energy of 100 Kev and the current of about 100 mA has been developed for using the high dose ion implantation, surface modification of steels and ceramics, and ion beam milling. The characteristics of the beam extraction and transportation are investigated. A duoPIGatron ion source compatible with gas ion extraction of about 100 mA, a single gap acceleration tube which is able to compensate the divergence due to the space charge effect, and a beam transport system with the concept of the space charge neutralization are developed for the high current machine. The performance of the constructed machine shows that nitrogen, argon, helium, hydrogen and oxygen ion beams are successfully extracted and transported at a beam divergence due to space charge effect is negligible in the operation pressure of 2 x 10 -5 torr. (author)

  14. Current's Fluctuations through Molecular Wires Composed of Thiophene Rings.

    Science.gov (United States)

    Ojeda Silva, Judith Helena; Cortés Peñaranda, Juan Camilo; Gómez Castaño, Jovanny A; Duque, Carlos Alberto

    2018-04-11

    We study theoretically the electronic transport and quantum fluctuations in single-molecule systems using thiophene rings as integrated elementary functions, as well as the dependence of these properties with the increase of the coupled rings, i.e., as a quantum wire. In order to analyze the current flow through these molecular systems, the thiophene rings are considered to be connected to metal contacts, which, in general terms, will be related to the application of voltages (bias voltages or gate voltages) to generate non-equilibrium behavior between the contacts. Due to the nonlinear behavior that is generated when said voltages are applied, it is possible to observe quantum fluctuations in the transport properties of these molecular wires. For the calculation of the transport properties, we applied a tight-binding approach using the Landauer-Büttiker formalism and the Fischer-Lee relationship, by means of a semi-analytic Green's function method within a real-space renormalization (decimation procedure). Our results showed an excellent agreement with results using a tight-binding model with a minimal number of parameters reported so far for these molecular systems.

  15. The Cornell field-reversed ion ring experiment FIREX: experimental design and first results

    Energy Technology Data Exchange (ETDEWEB)

    Podulka, W J; Greenly, J B; Anderson, D E; Glidden, S C; Hammer, D A; Omelchenko, Yu A; Sudan, R N [Cornell Univ., Ithaca, NY (United States). Laboratory of Plasma Studies

    1997-12-31

    The goal of FIREX (Field-reversed Ion Ring EXperiment) is to produce a fully field-reversed ring with 1 MeV protons. Such a ring requires about (2-3) x 10{sup 17} protons, or 30-50 mC of charge. This charge is to be injected as an annular proton beam through a suitable magnetic cusp configuration to produce a compact ring. The critical design issues for the ion beam accelerator are described. First experimental results of ion diode operation indicate that the design is capable of producing the required beam parameters. (author). 4 figs., 4 refs.

  16. The Cornell field-reversed ion ring experiment FIREX: experimental design and first results

    International Nuclear Information System (INIS)

    Podulka, W.J.; Greenly, J.B.; Anderson, D.E.; Glidden, S.C.; Hammer, D.A.; Omelchenko, Yu.A.; Sudan, R.N.

    1996-01-01

    The goal of FIREX (Field-reversed Ion Ring EXperiment) is to produce a fully field-reversed ring with 1 MeV protons. Such a ring requires about (2-3) x 10 17 protons, or 30-50 mC of charge. This charge is to be injected as an annular proton beam through a suitable magnetic cusp configuration to produce a compact ring. The critical design issues for the ion beam accelerator are described. First experimental results of ion diode operation indicate that the design is capable of producing the required beam parameters. (author). 4 figs., 4 refs

  17. Oscillatory persistent currents in self-assembled quantum rings.

    Science.gov (United States)

    Kleemans, N A J M; Bominaar-Silkens, I M A; Fomin, V M; Gladilin, V N; Granados, D; Taboada, A G; García, J M; Offermans, P; Zeitler, U; Christianen, P C M; Maan, J C; Devreese, J T; Koenraad, P M

    2007-10-05

    We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural properties determined by cross-sectional scanning tunneling microscopy measurements. The observed oscillation magnitude of the magnetic moment per electron is remarkably large for the topology of our nanostructures, which are singly connected and exhibit a pronounced shape asymmetry.

  18. Design considerations for a feedback system to control self-bunching in ion-storage rings

    International Nuclear Information System (INIS)

    Ziemann, V.

    2001-02-01

    We discuss the feasibility of a feedback system to cure self-bunching of the electron-cooled coasting ion-beam in CELSIUS. Such a system may also aid stable operation of accumulator rings for future spallation neutron sources or heavy ion rings used for inertial fusion energy production

  19. Lattice design of HISTRAP: Heavy ion storage ring for atomic physics

    International Nuclear Information System (INIS)

    Lee, I.Y.; Martin, J.A.; McGrory, J.B.; Milner, W.T.; Olsen, D.K.; Young, G.R.

    1987-01-01

    HISTRAP, a Heavy-Ion Storage Ring for Atomic Physics, is a proposed 46.8-m-circumference synchrotron-cooling-storage ring optimized to accelerate, cool, decelerate, and store beams of highly charged very-heavy ions at energies appropriate for advanced atomic physics research. This four-fold symmetrical ring has a maximum bending power of 2 Tm. It has achromatic bends and uses quadrupole triplets for focusing

  20. Pulsed high current ion beam processing equipment

    International Nuclear Information System (INIS)

    Korenev, S.A.; Perry, A.

    1995-01-01

    A pulsed high voltage ion source is considered for use in ion beam processing for the surface modification of materials, and deposition of conducting films on different substrates. The source consists of an Arkad'ev-Marx high voltage generator, a vacuum ion diode based on explosive ion emission, and a vacuum chamber as substrate holder. The ion diode allows conducting films to be deposited from metal or allow sources, with ion beam mixing, onto substrates held at a pre-selected temperature. The main variables can be set in the ranges: voltage 100-700 kV, pulse length 0.3 μs, beam current 1-200 A depending on the ion chosen. The applications of this technology are discussed in semiconductor, superconductor and metallizing applications as well as the direction of future development and cost of these devices for commercial application. 14 refs., 6 figs

  1. Proceedings of the 1979 workshop on beam current limitations in storage rings, July 16-27, 1979

    International Nuclear Information System (INIS)

    Pellegrini, C.

    1979-01-01

    The Workshop on Beam Current Limitations in Storage Rings was held at Brookhaven National Laboratory from July 16 to 27, 1979. The purpose of this Workshop was to discuss the physical mechanisms limiting the beam current or current density in accelerators or storage rings. Many of these machines are now being built or planned for a variety of applications, such as colliding beam experiments, synchrotron light production, heavy ion beams. This diversity was reflected in the Workshop and in the papers which have been contributed to these Proceedings. The twenty-one papers from the workshop were incorporated individually in the data base

  2. Development of a high current H- injector for the proton storage ring at LAMPF

    International Nuclear Information System (INIS)

    York, R.L.; Stevens, R.R.; DeHaven, R.A.; McConnell, J.R.; Chamberlin, E.P.; Kandarian, R.

    1984-01-01

    A new high-current H - injector has been installed at LAMPF for the Proton Storage Ring. The injector is equipped with a multicusp surface-production H - ion source that was developed at LAMPF. The ion source is capable of long-term operation at 20 mA of H - current at 10% duty factor and with normalized beam emittance of 0.08 cm-mrad (95% beam fraction). Details of the development program, the injector design, and initial operating experience are discussed. Included in the discussion is a comparison of intensity and emittance measurements of the same H - beam at 100 keV and 750 keV. 4 references, 6 figures

  3. High current density ion beam measurement techniques

    International Nuclear Information System (INIS)

    Ko, W.C.; Sawatzky, E.

    1976-01-01

    High ion beam current measurements are difficult due to the presence of the secondary particles and beam neutralization. For long Faraday cages, true current can be obtained only by negative bias on the target and by summing the cage wall and target currents; otherwise, the beam will be greatly distorted. For short Faraday cages, a combination of small magnetic field and the negative target bias results in correct beam current. Either component alone does not give true current

  4. The physics of highly charged heavy ions revealed by storage/cooler rings

    International Nuclear Information System (INIS)

    Mokler, P.H.; Stoehlker, T.

    1996-01-01

    With the successful commissioning of storage and cooler rings for bright beams of very heavy ions near the threshold of the last decade of this century, not only did a prosperous development in heavy ion accelerator technology come to its present summit, but also fundamental fields in heavy ion physics were opened widely for exciting explorations. Now, essential aspects in this area are accessible, aspects one only dared to dream of another decade ago. In the meantime, great progress already has been made in the fundamental physics in this field. This is particularly true for achievements in the atomic physics of highly charged heavy ions. In this chapter, we present a review of the current advances in this rapidly developing field. There are two general domains to be considered in the atomic physics of highly charged heavy ions: the fields of collisions and of atomic structure. Both aspects have to be explored equally, as they are strongly interconnected. One has to investigate the interaction processes to know, for instance, the population of excited states to help answer questions on the atomic structure; and conversely, one has to know the structure to understand the interactions. In both the fields, fundamental principles can be studied uniquely. This is in particular true for the heaviest ion species with only a few- or even zero-electrons left. 140 refs., 39 figs

  5. Modeling photo-desorption in high current storage rings

    International Nuclear Information System (INIS)

    Barletta, W.A.

    1991-01-01

    High luminosity flavor factories are characterized by high fluxes of synchrotron radiation that lead to thermal management difficulties. The associated photo-desorption from the vacuum chamber walls presents an additional design challenge, providing a vacuum system suitable for maintaining acceptable beam-gas lifetimes and low background levels of scattered radiation in the detector. Achieving acceptable operating pressures (1-10 nTorr) with practical pumping schemes requires the use of materials with low photodesorption efficiency operating in a radiation environment beyond that of existing storage rings. Extrapolating the existing photo-desorption data base to the design requirements of high luminosity colliders requires a physical model of the differential cleaning in the vacuum chamber. The authors present a simple phenomenological model of photodesorption that includes effects of dose dependence and diffuse photon reflection to compute the leveling of gas loads in beamlines of high current storage rings that typify heavy flavor factories. This model is also used to estimate chamber commissioning times

  6. Beam-based measurements of persistent current decay in the Relativistic Heavy Ion Collider

    Directory of Open Access Journals (Sweden)

    W. Fischer

    2001-04-01

    Full Text Available The two rings of the Relativistic Heavy Ion Collider are equipped with superconducting dipole magnets. At injection, induced persistent currents in these magnets lead to a sextupole component. As the persistent currents decay with time, the horizontal and vertical chromaticities change. From magnet measurements of persistent current decays, chromaticity changes in the machine are estimated and compared with chromaticity measurements.

  7. Access of energetic particles to storm time ring current through enhanced radial diffusion

    International Nuclear Information System (INIS)

    Lyons, L.R.; Schulz, M.

    1989-01-01

    Magnetic storms are distinguishable from other periods of geomagnetic activity by the injection of trapped electrons and ions to the 2 approx-lt L approx-lt 4 region. It has been proposed previously that this injection results from an inward displacement of the preexisting trapped-particle population by enhanced storm time electric fields. However, high-energy (approx-gt 40 keV) ring-current particles have drift periods that are typically shorter than the time of the main-phase development, and so the direct radial transport of these particles is restricted. The authors propose here that the transport of approx-gt 40 keV particles into the storm time ring current can result from enhanced stochastic radial transport driven by fluctuating electric fields during a storm's main phase. They estimate the effects of such electric fields by applying radial-diffusion theory, assuming a preexisting trapped-particle population as the initial conditions, and they demonstrate the feasibility of explaining observed flux increases of approx-gt 40-keV particles at L approx-lt 4 by enhanced radial diffusion. It is necessary that new particles be injected near the outer boundary of the trapping region so as to maintain the fluxes there as an outer boundary condition, and they estimate that the approx-gt 40-keV portion of the storm time ring current at L ∼ 3 consists of about 50% preexisting and about 50% new particles. They thus find that formation of the storm time ring current may be explainable via a combination of direct radial transport at energies approx-lt 40 keV and diffusive radial transport at higher energies

  8. 3-D studies of the formation and stability of strong ion rings

    International Nuclear Information System (INIS)

    Omelchenko, Yu.A.; Sudan, R.N.

    1996-01-01

    Complex 3-D simulations were conducted in support of the on-going experimental program, FIREX( (Field-Reversed Ion Ring Experiment) launched at the Cornell University to produce an ion ring magnetic field-reversed configuration by injecting an intense annular proton beam across a plasma-filled magnetic cusp region into a neutral gas immersed in a ramped solenoidal magnetic field. Previous axisymmetric PIC simulations performed with the FIRE code have demonstrated that strong ion rings (with a self-magnetic field large enough to reverse the applied field on axis) can be created using this technique on the equipment designed and assembled at Cornell. A new parallel object-oriented 3-D hybrid PIC code FLAME has been created to study questions of extreme importance to the success of the FIREX program, namely, the 3-D injection of a powerful ion beam into a strongly magnetized plasma, formation of a field-reversed ring, and the stability and equilibrium of such rings to toroidal perturbations. Using FLAME, the stability was studied of the ring formation during the injection phase and at later times when the ring is virtually stopped and the applied magnetic field is nearly reversed. The simulations revealed the effect of toroidal aberrations in the axially ramped magnetic field on the ion ring formation. (author). 4 figs., 4 refs

  9. 3-D studies of the formation and stability of strong ion rings

    Energy Technology Data Exchange (ETDEWEB)

    Omelchenko, Yu A; Sudan, R N [Cornell Univ., Ithaca, NY (United States). Laboratory of Plasma Studies

    1997-12-31

    Complex 3-D simulations were conducted in support of the on-going experimental program, FIREX( (Field-Reversed Ion Ring Experiment) launched at the Cornell University to produce an ion ring magnetic field-reversed configuration by injecting an intense annular proton beam across a plasma-filled magnetic cusp region into a neutral gas immersed in a ramped solenoidal magnetic field. Previous axisymmetric PIC simulations performed with the FIRE code have demonstrated that strong ion rings (with a self-magnetic field large enough to reverse the applied field on axis) can be created using this technique on the equipment designed and assembled at Cornell. A new parallel object-oriented 3-D hybrid PIC code FLAME has been created to study questions of extreme importance to the success of the FIREX program, namely, the 3-D injection of a powerful ion beam into a strongly magnetized plasma, formation of a field-reversed ring, and the stability and equilibrium of such rings to toroidal perturbations. Using FLAME, the stability was studied of the ring formation during the injection phase and at later times when the ring is virtually stopped and the applied magnetic field is nearly reversed. The simulations revealed the effect of toroidal aberrations in the axially ramped magnetic field on the ion ring formation. (author). 4 figs., 4 refs.

  10. High current pelletron for ion implantation

    International Nuclear Information System (INIS)

    Schroeder, J.B.

    1989-01-01

    Since 1984, when the first production MeV ion implanter (an NEC model MV-T30) went on-line, interest in versatile electrostatic accelerator systems for MeV ion implantation has grown. The systems use a negative ion source to inject a tandem megavolt accelerator. In early systems the 0.4 mA of charging current from the two Pelletron charging chains in the accelerator was sufficient for the low intensity of beams from the ion source. This 2-chain system, however, is no longer adequate for the much higher beam intensities from today's improved ion sources. A 4-chain charging system, which delivers 1.3 mA to the high voltage terminal, was developed and is in operation in new models of NEC S Series Pelletron accelerators. This paper describes the latest beam performance of 1 MV and 1.7 MW Pelletron accelerators with this new 4-chain charging system. (orig.)

  11. Relativistic, QED and nuclear effects in highly charged ions revealed by resonant electron-ion recombination in storage rings

    OpenAIRE

    Schippers, Stefan

    2008-01-01

    Dielectronic recombination (DR) of few-electron ions has evolved into a sensitive spectroscopic tool for highly charged ions. This is due to technological advances in electron-beam preparation and ion-beam cooling techniques at heavy-ion storage rings. Recent experiments prove unambiguously that DR collision spectroscopy has become sensitive to 2nd order QED and to nuclear effects. This review discusses the most recent developments in high-resolution spectroscopy of low-energy DR resonances, ...

  12. Magnetic field of the magnetospheric ring current and its dynamics during magnetic storms

    International Nuclear Information System (INIS)

    Feldstein, Y.I.; Grafe, A.; Pisarsky, V.Yu.; Prigansova, A.; Sumaruk, P.V.

    1990-01-01

    This review examines models existing in the literature which describe the magnetic field produced by the ring current (DR) at the Earth's surface based on the energy balance equation. The parameters of this equation, the injection function F and decay parameter τ are considered to depend on parameters of the interplanetary medium and the DR intensity. The existing models are shown to be able to describe the DR variations with sufficient accuracy (r.m.s. deviation δ between the experimental and modelled values of DR for 170 magnetic storms is 5 < δ < 15 nT, and the correlation coefficient between the two is 0.85 < r < 1). The models describe that part of the geomagnetic field variation at low latitudes during a magnetic storm that is controlled by the geoeffective characteristics of the interplanetary medium and which thus responds immediately to its variations (the driven part). The values of τ are significantly less during the main phase of a magnetic storm than during the recovery phase. This reflects the difference in the main mechanisms of ion loss from the ring current during the two phases of the storm. These are the interaction of ions with hydromagnetic waves during the main phase of the storm with its intervals of intense plasma injection into the inner magnetosphere, and charge exchange with the cold hydrogen geocorona during the recovery phase. (author)

  13. Importance of field-reversing ion ring formation in hot electron plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ikuta, K.

    1975-11-01

    Formation of the field reversing ion ring in the mirror confined hot electron plasma may offer a device to confine the fusion plasma even under the restriction of the present technology. (Author) (GRA)

  14. Separation of electron ion ring components (computational simulation and experimental results)

    International Nuclear Information System (INIS)

    Aleksandrov, V.S.; Dolbilov, G.V.; Kazarinov, N.Yu.; Mironov, V.I.; Novikov, V.G.; Perel'shtejn, Eh.A.; Sarantsev, V.P.; Shevtsov, V.F.

    1978-01-01

    The problems of the available polarization value of electron-ion rings in the regime of acceleration and separation of its components at the final stage of acceleration are studied. The results of computational simulation by use of the macroparticle method and experiments on the ring acceleration and separation are given. The comparison of calculation results with experiment is presented

  15. Adiabatic energization in the ring current and its relation to other source and loss terms

    Science.gov (United States)

    Liemohn, M. W.; Kozyra, J. U.; Clauer, C. R.; Khazanov, G. V.; Thomsen, M. F.

    2002-04-01

    The influence of adiabatic energization and deenergization effects, caused by particle drift in radial distance, on ring current growth rates and loss lifetimes is investigated. Growth and loss rates from simulation results of four storms (5 June 1991, 15 May 1997, 19 October 1998, and 25 September 1998) are examined and compared against the y component of the solar wind electric field (Ey,sw). Energy change rates with and without the inclusion of adiabatic energy changes are considered to isolate the influence of this mechanism in governing changes of ring current strength. It is found that the influence of adiabatic drift effects on the energy change rates is very large when energization and deenergization are considered separately as gain and loss mechanisms, often about an order of magnitude larger than all other source or loss terms combined. This is true not only during storm times, when the open drift path configuration of the hot ions dominates the physics of the ring current, but also during quiet times, when the small oscillation in L of the closed trajectories creates a large source and loss of energy each drift orbit. However, the net energy change from adiabatic drift is often smaller than other source and loss processes, especially during quiet times. Energization from adiabatic drift dominates ring current growth only during portions of the main phase of storms. Furthermore, the net-adiabatic energization is often positive, because some particles are lost in the inner magnetosphere before they can adiabatically deenergize. It is shown that the inclusion of only this net-adiabatic drift effect in the total source rate or loss lifetime (depending on the sign of the net-adiabatic energization) best matches the observed source and loss values from empirical Dst predictor methods (that is, for consistency, these values should be compared between the calculation methods). While adiabatic deenergization dominates the loss timescales for all Ey,sw values

  16. High current ion source development at Frankfurt

    Energy Technology Data Exchange (ETDEWEB)

    Volk, K.; Klein, H.; Lakatos, A.; Maaser, A.; Weber, M. [Frankfurt Univ. (Germany). Inst. fuer Angewandte Physik

    1995-11-01

    The development of high current positive and negative ion sources is an essential issue for the next generation of high current linear accelerators. Especially, the design of the European Spallation Source facility (ESS) and the International Fusion Material Irradiation Test Facility (IFMIF) have increased the significance of high brightness hydrogen and deuterium sources. As an example, for the ESS facility, two H{sup -}-sources each delivering a 70 mA H{sup -}-beam in 1.45 ms pulses at a repetition rate of 50 Hz are necessary. A low emittance is another important prerequisite. The source must operate, while meeting the performance requirements, with a constancy and reliability over an acceptable period of time. The present paper summarizes the progress achieved in ion sources development of intense, single charge, positive and negative ion beams. (author) 16 figs., 7 refs.

  17. High current ion source development at Frankfurt

    International Nuclear Information System (INIS)

    Volk, K.; Klein, H.; Lakatos, A.; Maaser, A.; Weber, M.

    1995-01-01

    The development of high current positive and negative ion sources is an essential issue for the next generation of high current linear accelerators. Especially, the design of the European Spallation Source facility (ESS) and the International Fusion Material Irradiation Test Facility (IFMIF) have increased the significance of high brightness hydrogen and deuterium sources. As an example, for the ESS facility, two H - -sources each delivering a 70 mA H - -beam in 1.45 ms pulses at a repetition rate of 50 Hz are necessary. A low emittance is another important prerequisite. The source must operate, while meeting the performance requirements, with a constancy and reliability over an acceptable period of time. The present paper summarizes the progress achieved in ion sources development of intense, single charge, positive and negative ion beams. (author) 16 figs., 7 refs

  18. Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

    Science.gov (United States)

    Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.

    2017-12-01

    High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

  19. Ion shaking in the 200 MeV XLS-ring

    International Nuclear Information System (INIS)

    Bozoki, E.; Kramer, S.L.

    1992-01-01

    It has been shown that ions, trapped inside the beam's potential, can be removed by the clearing electrodes when the amplitude of the ion oscillation is increased by vertically shaking the ions. We will report on a similar experiment in the 200 Mev XLS ring. The design of the ion clearing system for the ring and the first results obtained, were already reported. In the present series of experiments, RF voltage was applied on a pair of vertical strip-lines. The frequency was scanned in the range of the ion (from H 2 to CO 2 ) bounce frequencies in the ring (1--10 MHz). The response of the beam size, vertical betatron tune and lifetime was studied

  20. High-current pulsed ion source for metallic ions

    International Nuclear Information System (INIS)

    Gavin, B.; Abbott, S.; MacGill, R.; Sorensen, R.; Staples, J.; Thatcher, R.

    1981-03-01

    A new sputter-ion PIG source and magnet system, optimized for intermediate charge states, q/A of 0.02 to 0.03, is described. This source will be used with the new Wideroe-based injector for the SuperHILAC. Pulsed electrical currents of several emA of heavy metal ions have been produced in a normalized emittance area of .05π cm-mr. The source system is comprised of two electrically separate anode chambers, one in operation and one spare, which can be selected by remote control. The entire source head is small and quickly removable

  1. Ring current energy injection rate and solar wind-magnetosphere energy coupling

    International Nuclear Information System (INIS)

    Lee, L.C.; Kan, J.R.; Akasofu, S.-I.

    1982-01-01

    The purpose of this paper is to (i) formulate the ring current injection rate Usub(R) in terms of phisub(CT) (cross-tail potential drop) by assuming that the ring current formation is a direct consequence of an enhanced convection, (ii) examine the relationship between the injection rate Usub(R) and the power transferred from the solar wind to the magnetosphere and (iii) demonstrate that an enhanced convection indeed leads to the formation of the ring current. (author)

  2. Coherent instability of the heavy ion beam in the storage ring

    International Nuclear Information System (INIS)

    Noda, A.

    1981-01-01

    The storage ring as the final part of a driver for heavy ion fusion is required to provide heavy ions (A asymptotically equals 200) with energy of 5 -- 10 GeV and such a high intensity as 1 -- 6 x 10 15 ions/pulse. So as to raise the number of ions which can be accumulated in a ring, singlly charged heavy ion is used for its relatively smaller incoherent space charge force compared with higher charge states. The intensity limit due to incoherent space charge force is 0.7 -- 1.4 x 10 15 ions for U 1 + . Much more severe limits exist due to coherent motion of heavy ion beams (0.8 -- 2 x 10 13 for longitudinal motion and 0.9 -- 1.1 x 10 12 for transverse motion), because of the relatively lower velocity of the accumulated ions. It seems unrealistic to use a lot of rings in order to operate below such intensity limits of the above instability. Therefore the number of the storage rings is constrained within a reasonable value (3 -- 7) and the possibility of compressing the bunches of heavy ion beams before the instability grows fatally large is studied. (author)

  3. Ring-shaped Wigner crystals of trapped ions at the micronscale

    Science.gov (United States)

    Li, Haokun; Urban, Erik; Noel, Crystal; Chuang, Alexander; Xia, Yang; Hemmerling, Borge; Wang, Yuan; Zhang, Xiang; Haeffner, Hartmut

    Trapped ion crystals are ideal platforms to study many-body physics and quantum information processing, with both the internal electronic states and external motional degree-of-freedoms controllable at the single quantum level. In contrast to conventional, finite, linear chains of ions, a ring topology exhibiting periodic boundary conditions and rotational symmetry opens up a new directions to diverse topics. However, previous implementations of ion rings result in small aspect ratios (electrode distance to ring diameter, making the rotational symmetry of the ion crystals prone to stray electric fields from imperfections of the trap electrodes, particularly evident at low temperatures. Here, using a new trap design with a 60-fold improvement of this aspect ratio, we demonstrate crystallization of 40Ca+ ions in a ring with rotational energy barriers comparable to the thermal energy of Doppler laser cooled ion crystals. When further reducing the rotational energy barriers, we observe delocalization of the ion rings. With this result, we enter a regime where quantum topological effects can be studied and novel quantum computation and simulation experiments can be implemented.

  4. A Harmonic Kicker Scheme for the Circulator Cooler Ring in the Proposed Medium Energy Electron-Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Nissen, Edward W.; Hutton, Andrew M.; Kimber, Andrew J.

    2013-06-01

    The current electron cooler design for the proposed Medium Energy Electron-Ion collider (MEIC) at Jefferson Lab utilizes a circulator ring for reuse of the cooling electron bunch up to 100 times to cool the ion beams. This cooler requires a fast kicker system for injecting and extracting individual bunches in the circulator ring. Such a kicker must work at a high repetition rate, up to 7.5 to 75 MHz depending on the number of turns in the recirculator ring. It also must have a very short rise and fall time (of order of 1 ns) such that it will kick an individual bunch without disturbing the others in the ring. Both requirements are orders of magnitude beyond the present state-of-the-art as well as the goals of other on-going kicker R&D programs such as that for the ILC damping rings. In this paper we report a scheme of creating this fast, high repetition rate kicker by combining RF waveforms at multiple frequencies to create a kicker waveform that will, for example, kick every eleventh bunch while leaving the other ten unperturbed. We also present a possible implementation of this scheme as well as discuss its limitations.

  5. QED in highly-charged high Z ions - experiments at the storage ring ESR

    International Nuclear Information System (INIS)

    Mokler, P.H.

    1996-01-01

    A survey on the fundamental structure aspects of very heavy few -electron ions, in particular H-like systems, is presented. Special emphasis is given to contribution from quantum-electro-dynamics at strong central potentials. The technical possibilities to produce highly-charged heavy ions are reviewed and the ground-state Lamb-shift experiments performed at the heavy ion storage ring ESR are summarized. A short outlook on further developments in this field is added. (author). 23 refs, 9 figs

  6. Studies of Lifetimes in an Ion Storage Ring Using Laser Technique

    International Nuclear Information System (INIS)

    Rostohar, Danijela; Derkatch, Anna; Hartman, Henrik; Norlin, Lars-Olov; Royen, Peder; Schef, Peter; Mannervik, Sven

    2003-01-01

    The laser-probing method for lifetime measurements of metastable levels, performed by applying the Fast Ion Beam Laser (FIBLAS) method to ions stored in a storage ring, has been developed by the Stockholm group. Recently, we have applied this method to lifetime measurements of close lying metastable levels. In this paper we discuss experimental studies of ions with complex structure and present the first experimentally obtained lifetimes of selected metastable levels in complex systems as Fe + , Eu + and La + .

  7. Resonant pickups for non-destructive single-particle detection in heavy-ion storage rings and first experimental results

    International Nuclear Information System (INIS)

    Sanjari, Mohammad Shahab

    2013-01-01

    Nuclear astrophysics studies on highly charged radionuclides benefit from accelerator facilities with storage rings, where exotic nuclides produced with small yields can be efficiently investigated. Currently there are two accelerator facilities capable of storing highly charged heavy ions, GSI in Darmstadt and IMP in Lanzhou. Non-destructive detection methods are often used for in-flight measurements based on frequency analysis. The sensitivity of such detection systems are of primary importance specially when number of stored ions is small. Furthermore, since the exotic nuclides of interest are as a rule short-lived, the detectors must be fast. One common form of such detectors are parallel plate SCHOTTKY monitors, on which particles induce a mirror charge at each passage. This method has been successfully used at ESR experimental storage ring of GSI since 1991. In this work we describe a new resonant SCHOTTKY pickup operating as a high sensitive cavity current monitor which was mounted and commissioned in the ESR early 2010. It was successfully used in several storage ring experiments. A very similar pickup was mounted in CSRe at IMP Lanzhou in 2011. First in-ring tests have been performed and new experimental results are pending. The spectral analysis of acquired signals by the new detector has enabled a broad range of new physics experiments. The theory of operation and first experimental results and future perspectives are presented in this thesis.

  8. Resonant pickups for non-destructive single-particle detection in heavy-ion storage rings and first experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Sanjari, Mohammad Shahab

    2013-04-26

    Nuclear astrophysics studies on highly charged radionuclides benefit from accelerator facilities with storage rings, where exotic nuclides produced with small yields can be efficiently investigated. Currently there are two accelerator facilities capable of storing highly charged heavy ions, GSI in Darmstadt and IMP in Lanzhou. Non-destructive detection methods are often used for in-flight measurements based on frequency analysis. The sensitivity of such detection systems are of primary importance specially when number of stored ions is small. Furthermore, since the exotic nuclides of interest are as a rule short-lived, the detectors must be fast. One common form of such detectors are parallel plate SCHOTTKY monitors, on which particles induce a mirror charge at each passage. This method has been successfully used at ESR experimental storage ring of GSI since 1991. In this work we describe a new resonant SCHOTTKY pickup operating as a high sensitive cavity current monitor which was mounted and commissioned in the ESR early 2010. It was successfully used in several storage ring experiments. A very similar pickup was mounted in CSRe at IMP Lanzhou in 2011. First in-ring tests have been performed and new experimental results are pending. The spectral analysis of acquired signals by the new detector has enabled a broad range of new physics experiments. The theory of operation and first experimental results and future perspectives are presented in this thesis.

  9. Ionospheric storm effects in the nighttime E region caused by neutralized ring current particles

    Directory of Open Access Journals (Sweden)

    R. Bauske

    1997-03-01

    Full Text Available During magnetic storms an anomalous increase in the ionization density of the nighttime E region is observed at low and middle latitudes. It has been suggested that this effect is caused by the precipitation of neutralized ring current particles. Here a coupled ring current decay-ionosphere model is used to confirm the validity of this explanation.

  10. Nonextensive electron and ion dust charging currents

    International Nuclear Information System (INIS)

    Amour, Rabia; Tribeche, Mouloud

    2011-01-01

    The correct nonextensive electron and ion charging currents are presented for the first time based on the orbit motion limited approach. For -1< q<1, where q measures the amount of plasma nonextensivity, the nonextensive electron charging current is expressed in terms of the hypergeometric function. The variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate succinctly the effects of nonextensive charge carriers. The obtained formulas bring a possibility to build theories on nonlinear collective process in variable charge nonextensive dusty plasmas.

  11. Truncated exponential-rigid-rotor model for strong electron and ion rings

    International Nuclear Information System (INIS)

    Larrabee, D.A.; Lovelace, R.V.; Fleischmann, H.H.

    1979-01-01

    A comprehensive study of exponential-rigid-rotor equilibria for strong electron and ion rings indicates the presence of a sizeable percentage of untrapped particles in all equilibria with aspect-ratios R/a approximately <4. Such aspect-ratios are required in fusion-relevant rings. Significant changes in the equilibria are observed when untrapped particles are excluded by the use of a truncated exponential-rigid-rotor distribution function. (author)

  12. X-ray spectroscopy of highly-charged ions in a storage ring. Invited lecture

    International Nuclear Information System (INIS)

    Beyer, H.F.

    1994-11-01

    The purpose of the present lectures is to carry through the methods and procedures necessary for a meaningful spectroscopy of the heaviest few-electron ions in relation to present theories. Results achieved so far in accelerator-based X-ray experiments are highlighted with emphasis on recent developments on heavy-ion storage rings. Starting with a brief account of the basics of one-electron ions, the motivation for doing X-ray spectroscopy of the simplest atomic systems with a high nuclear charge is given. In section 2 X-ray instrumentation and techniques are discussed including the precautions necessary when dealing with fast-beam sources. Peculiarities of heavy-ion storage rings are investigated in section 3 with regard to their use for spectroscopy. In section 4 are discussed results obtained so far on the measurement of the Lamb shift in very heavy ions. Section 5 gives some perspectives for the near future. (orig.)

  13. Ion rings for magnetic fusion. Technical progress report, August 1, 1993--June 1, 1994

    International Nuclear Information System (INIS)

    Sudan, R.N.

    1994-01-01

    In Our Proposal ''Ion Rings for Magnetic Fusion'' of January 6, 1993, Stage I of our Proposed Program plan (the 12 months) consisted of the following tasks: Experiments on the existing ion ring experimental system IREX to test a new magnetically-controlled anode plasma source (MAP) for the ion beam diode injector; numerical simulations of ion ring formation to optimize design parameters for the field reversed ion ring experiment (FIREX) to be built and operated in Stage II; and designing the power supply for the FIREX injector and the magnetic field system using results for A and B. During the past 7 1/2 months our work has progressed according to the above plan. In addition to testing the MAP diode on IREX we have tested the EMFAPS (evaporating metal film anode plasma source) anode on the Sandia National Laboratories funded LION pulsed power generator. As a result of these experiments, described this paper, we have arrived at the conclusion that EMFAPS anode for the ion at present because the MAP diode beam diode injector is our preferred choice for is still in an early stage of development

  14. Current neutralization of converging ion beams

    International Nuclear Information System (INIS)

    Mosher, D.

    1978-01-01

    It is desired to consider the problem of current neutralization of heavy ion beams traversing gas backgrounds in which the conductivity changes due to beam heating and beam convergence. The procedure is to determine Green's-function solutions to the magnetic-diffusion equation derived from Maxwell's equations and an assumed scaler-plasma conductivity sigma for the background-electron current density j/sub e/. The present calculation is more general than some previously carried out in that arbitrary time variations for the beam current j/sub b/ and conductivity are allowed and the calculation is valid for both weak and strong neutralization. Results presented here must be combined with an appropriate energy-balance equation for the heated background in order to obtain the neutralization self-consistently

  15. Electron impact single detachment on the F- ions using the heavy ion storage ring CRYRING: cross-section determination

    International Nuclear Information System (INIS)

    Andersson, K.; Hanstorp, D.; Oesterdahl, F.; Danared, H.; Kaellberg, A.

    2001-01-01

    Electron Impact Single Detachment (EISD) of F - has been studied using the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm, Sweden. F - ions stored in the ring were merged with an electron beam in one of the ring sections. Neutral F atoms produced in the EISD process were detected in the zero-degree direction using a surface barrier detector. The threshold for the detachment process was found to be around 7.6 eV, thus more than twice the binding energy of F - . The cross-sections increased smoothly up to 55 eV where it reached a maximum of 1.9 x 10 -16 cm 2 . At higher energies a slow decrease of the cross-section was observed, which follows the energy dependence predicted by the Bethe-Born approximation. The experiment showed that CRYRING can be used favourably for studies of anions, and several experiments are forthcoming. (orig.)

  16. HISTRAP [Heavy Ion Storage Ring for Atomic Physics] prototype hardware studies

    International Nuclear Information System (INIS)

    Olsen, D.K.; Atkins, W.H.; Dowling, D.T.; Johnson, J.W.; Lord, R.S.; McConnell, J.W.; Milner, W.T.; Mosko, S.W.; Tatum, B.A.

    1989-01-01

    HISTRAP, Heavy Ion Storage Ring for Atomic Physics, is a proposed 2.67-Tm synchrotron/cooler/storage ring optimized for advanced atomic physics research which will be injected with ions from either the HHIRF 25-MV tandem accelerator or a dedicated ECR source and RFQ linac. Over the last two years, hardware prototypes have been developed for difficult and long lead-time components. A vacuum test stand, the rf cavity, and a prototype dipole magnet have been designed, constructed, and tested. 7 refs., 8 figs., 2 tabs

  17. Loss pattern of Pb ions with charge changing processes in the LEIR ring

    CERN Document Server

    Pasternak, J

    2004-01-01

    Avalanche like pressure rise and an associated decrease of the beam lifetime, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators. The vacuum system of the LEIR ring has to be upgraded carefully to avoid that these phenomena prevent the machine from reaching design performance. The loss pattern of Pb ions having captured an electron presented in this report allows to estimate whether the low dynamic pressure needed for LEIR is reachable. Efficient interception of lost ions with low beam loss induced outgassing absorber blocks, installed at appropriate locations is promising.

  18. Strong-field physics using lasers and relativistic heavy ions at the high-energy storage ring HESR at FAIR

    International Nuclear Information System (INIS)

    Kuehl, T; Bagnoud, V; Stoehlker, T; Litvinov, Y; Winters, D F A; Zielbauer, B; Backe, H; Spielmann, Ch; Seres, J; Tünnermann, A; Neumayer, P; Aurand, B; Namba, S; Zhao, H Y

    2014-01-01

    The HESR high-energy ion storage ring at FAIR will provide unprecedented possibilities for strong-field physics using novel laser sources on relativistic heavy ions. An overview on the planning will be given.

  19. Light ion EDM search in magnetic storage rings

    International Nuclear Information System (INIS)

    Onderwater, C. J. G.

    2006-01-01

    Permanent electric dipole moments (EDMs) violate parity and time-reversal symmetry. Within the Standard Model (SM), they require CP violation and are many orders of magnitude below present experimental sensitivity. Many extensions of the SM predict much larger EDMs, which are therefore an excellent probe for the existence of 'new physics.' So far only electrically neutral systems were used for sensitive searches of EDMs. Several techniques, based on storing fast particles in a magnetic storage ring, are being developed to probe charged particles for an EDM. With the introduction of these novel experimental methods, high sensitivity for charged systems, in particular light nuclei, is within reach.

  20. Electron and ion currents relevant to accurate current integration in MeV ion backscattering spectrometry

    International Nuclear Information System (INIS)

    Matteson, S.; Nicolet, M.A.

    1979-01-01

    The magnitude and characteristics of the currents which flow in the target and the chamber of an MeV ion backscattering spectrometer are examined. Measured energy distributions and the magnitude of high-energy secondary electron currents are reported. An empirical universal curve is shown to fit the energy distribution of secondary electrons for several combinations of ion energy, targets and ion species. The magnitude of tertiary electron currents which arise at the vacuum vessel walls is determined for various experimental situations and is shown to be non-negligible in many cases. An experimental arrangement is described which permits charge integrations to 1% arruracy without restricting access to the target as a Faraday cage does. (Auth.)

  1. Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

    International Nuclear Information System (INIS)

    Kovalenko, Oleksandr

    2015-01-01

    The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U 90+ beam at the existing storage ring ESR, GSI.

  2. Ion optics and beam dynamics optimization at the HESR storage ring for the SPARC experiments with highly charged heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, Oleksandr

    2015-06-24

    The High-Energy Storage Ring (HESR) is a part of an upcoming International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. A key part of a scientific program, along with antiproton physics, will be physics with highly-charged heavy ions. Phase-space cooled beams together with fixed internal target will provide an excellent environment for storage ring experiments at the HESR for the SPARC collaboration. Until recently, however, the existing ion optical lattice for the HESR was designed only for the experiments with antiproton beams. The thesis presents a new ion optical mode developed specifically for the operation of the HESR with highly charged heavy ions. The presence of the errors, such as beam momentum spread, magnetic field impurities or magnets misalignments, leads to disruption of beam dynamics: exciting of resonant motion and loss of beam stability. Within the paper, these effects are investigated with the help of numerical codes for particle accelerator design and simulation MAD-X and MIRKO. A number of correction techniques are applied to minimize the nonlinear impact on the beam dynamics and improve the experimental conditions. The application of the analytical and numerical tools is demonstrated in the experiment with uranium U{sup 90+} beam at the existing storage ring ESR, GSI.

  3. Persistent current and transmission probability in the Aharonov-Bohm ring with an embedded quantum dot

    International Nuclear Information System (INIS)

    Wu Suzhi; Li Ning; Jin Guojun; Ma Yuqiang

    2008-01-01

    Persistent current and transmission probability in the Aharonov-Bohm (AB) ring with an embedded quantum dot (QD) are studied using the technique of the scattering matrix. For the first time, we find that the persistent current can arise in the absence of magnetic flux in the ring with an embedded QD. The persistent current and the transmission probability are sensitive to the lead-ring coupling and the short-range potential barrier. It is shown that increasing the lead-ring coupling or the short-range potential barrier causes the suppression of the persistent current and the increasing resonance width of the transmission probability. The effect of the potential barrier on the number of the transmission peaks is also investigated. The dependence of the persistent current and the transmission probability on the magnetic flux exhibits a periodic property with period of the flux quantum

  4. Cascade Problems in Some Atomic Lifetime Measurements at a Heavy-Ion Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E; Hoffmann, J; Krantz, C; Wolf, A; Ishikawa, Y; Santana, J

    2008-10-09

    Lifetimes of 3s{sup 2}3p{sup k} ground configuration levels of Al-, Si-, P-, and S-like ions of Be, Co, and Ni have been measured at a heavy-ion storage ring. Some of the observed decay curves show strong evidence of cascade repopulation from specific 3d levels that feature lifetimes in the same multi-millisecond range as the levels of the ground configuration.

  5. Field-reversing electron and ion rings for the confinement and heating of plasmas. Annual progress report, September 1, 1980-August 31, 1981

    International Nuclear Information System (INIS)

    Fleischmann, H.H.

    1981-09-01

    Our experimental work on the RECE-Christa device during the present period concentrated on obtaining conditions for first measurements of plasma confinement and on the generation of mixed-CT configurations. The most important results in these areas included the generation of rings with plasma currents significantly larger than originally hoped for, and - on the other hand - a failure to propagate rings efficiently in background gas densities below 1 mTorr. In addition, a digital data management system has been acquired and the respective software is being completed. Finally, theoretical work was performed on calculating banana drift orbits in Spheromak-type configurations and on developing a semi-analytic model for the equilibrium of ion rings which could be used for estimating the ring behavior during the slow-down of the ions

  6. Digital DC beam current measurement on SSRF storage ring

    International Nuclear Information System (INIS)

    Xiong Liang; Yin Chongxian; Liu Ming; Chen Jianfeng

    2011-01-01

    Both DC current transformer (DCCT) and integrating current transformer (ICT) can be used in DC beam current measurement. The ICT has strong capability of resisting electromagnetic interference, but its measurement accuracy cannot satisfy the DC beam current measurement requirement when using traditional high speed A/D. With high resolution A/D and equivalent sampling system, DC beam current measuring system based on ICT can reach high accuracy compared with DCCT system. In this paper, the ICT-based DC beam current measurement, equivalent sampling method and testing results at Shanghai Synchrotron Radiation Facility(SSRF) is described. (authors)

  7. Development of capacitive beam position, beam current and Schottky-signal monitors for the Cryogenic Storage Ring (CSR)

    International Nuclear Information System (INIS)

    Laux, Felix

    2011-01-01

    In this thesis novel techniques based on capacitive pickups for the determination of the beam current, the beam position and the Schottky-signal in storage rings have been developed. Beam current measurements at the heavy ion storage ring TSR with a capacitive pickup have been found in very good agreement with the theory. Using this device the accurate measurement of beam currents at the TSR far below 1 μA is now possible. This method will also be used at the Cryogenic Storage Ring (CSR) at which beam currents in the range of 1 nA-1 μA are expected. For the first time, position measurements with a resonant amplifier system for capacitive pickups have been examined at the TSR for later use of this technique in the CSR. With this method an increased signal-to-noise ratio can be achieved using a parallel inductance. A comparison with measurements using the rest gas beam profile monitor has shown very good agreement even at very low intensities. Experiments with the cryo-capable electronics for the CSR beam position monitors have shown an achievable quality factor of Q=500, resulting in the prospect of precise position measurements at the CSR even at very low beam currents. The CSR Schottky-Pickup will also be equipped with a resonant amplifier system with a comparable quality factor. An estimation of the signal-to-noise ratio suggests a detection limit of a few protons. (orig.)

  8. Coulomb collisions of ring current particles: Indirect source of heat for the ionosphere

    Science.gov (United States)

    Cole, K. D.

    1975-01-01

    The additional energy requirements of the topside ionosphere during a magnetic storm are less than one quarter of the ring current energy. This energy is supplied largely by Coulomb collisions of ring current protons of energy less than about 20 keV with background thermal electrons which conduct the heat to the ionosphere. Past criticisms are discussed of this mechanism for the supply of energy to the SAR-arc and neighboring regions of the ionosphere.

  9. A renormalization group study of persistent current in a quasiperiodic ring

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Paramita [Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata-700 064 (India); Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108 (India); Karmakar, S.N. [Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata-700 064 (India)

    2014-04-01

    We propose a real-space renormalization group approach for evaluating persistent current in a multi-channel quasiperiodic Fibonacci tight-binding ring based on a Green's function formalism. Unlike the traditional methods, the present scheme provides a powerful tool for the theoretical description of persistent current with a very high degree of accuracy in large periodic and quasiperiodic rings, even in the micron scale range, which emphasizes the merit of this work.

  10. Localized persistent spin currents in defect-free quasiperiodic rings with Aharonov–Casher effect

    International Nuclear Information System (INIS)

    Qiu, R.Z.; Chen, C.H.; Cheng, Y.H.; Hsueh, W.J.

    2015-01-01

    We propose strongly localized persistent spin current in one-dimensional defect-free quasiperiodic Thue–Morse rings with Aharonov–Casher effect. The results show that the characteristics of these localized persistent currents depend not only on the radius filling factor, but also on the strength of the spin–orbit interaction. The maximum persistent spin currents in systems always appear in the ring near the middle position of the system array whether or not the Thue–Morse rings array is symmetrical. The magnitude of the persistent currents is proportional to the sharpness of the resonance peak, which is dependent on the bandwidth of the allowed band in the band structure. The maximum persistent spin currents also increase exponentially as the generation order of the system increases. - Highlights: • Strongly localized persistent spin current in quasiperiodic AC rings is proposed. • Localized persistent spin currents are much larger than those produced by traditional mesoscopic rings. • Characteristics of the localized persistent currents depend on the radius filling factor and SOI strength. • The maximum persistent current increases exponentially with the system order. • The magnitude of the persistent currents is related to the sharpness of the resonance

  11. Ring Current Response to Different Storm Drivers. Van Allen Probes and Cluster Observations.

    Science.gov (United States)

    Bingham, S.; Mouikis, C.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

    2015-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), co-rotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure change the global magnetic field, which affects the transport of the radiation belts. In order to determine the field changes during a storm it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. The source population of the storm time ring current is the night side plasma sheet. However, it is not clear how these convecting particles affect the storm time ring current pressure development. We use Van Allen Probes and Cluster observations together with the Volland-Stern and dipole magnetic field models to determine the contribution in the ring current pressure of the plasma sheet particles convecting from the night side that are on open drift paths, during the storm evolution. We compare storms that are related to different interplanetary drivers, CME and CIR, as observed at different local times.

  12. Lifetimes of relativistic heavy-ion beams in the High Energy Storage Ring of FAIR

    Science.gov (United States)

    Shevelko, V. P.; Litvinov, Yu. A.; Stöhlker, Th.; Tolstikhina, I. Yu.

    2018-04-01

    The High Energy Storage Ring, HESR, will be constructed at the Facility for Antiproton and Ion Research, FAIR, Darmstadt. For the first time, it will be possible to perform experiments with cooled high-intensity stable and radioactive heavy ions at highly relativistic energies. To design experiments at the HESR, realistic estimations of beam lifetimes are indispensable. Here we report calculated cross sections and lifetimes for typical U88+ , U90+ , U92+ , Sn49+ and Sn50+ ions in the energy range E = 400 MeV/u-5 GeV/u, relevant for the HESR. Interactions with the residual gas and with internal gas-jet targets are also considered.

  13. Simulation studies of electron acceleration by ion ring distributions in solar flares

    International Nuclear Information System (INIS)

    McClements, K.G.; Bingham, R.; Su, J.J.; Dawson, J.M.; Spicer, D.S.

    1990-07-01

    Using a 21/2-D fully relativistic electromagnetic particle-in-cell code (PIC) we have investigated a potential electron acceleration mechanism in solar flares. The free energy is provided by ions which have a ring velocity distribution about the magnetic field direction. Ion rings may be produced by perpendicular shocks, which could in turn be generated by the super-Alfvenic motion of magnetic flux tubes emerging from the photosphere or by coronal mass ejections (CMEs). Such ion distributions are known to be unstable to the generation of lower hybrid waves, which have phase velocities in excess of the electron thermal speed parallel to the field and can therefore resonantly accelerate electrons in that direction. The simulations show the transfer of perpendicular ion energy to energetic electrons via lower hybrid wave turbulence. With plausible ion ring velocities, the process can account for the observationally inferred fluxes and energies of non-thermal electrons during the impulsive phase of flares. Our results also show electrostatic wave generation close to the plasma frequency: we suggest that this is due to bump-in-tail instability of the electron distribution. (author)

  14. A Collimation Scheme for Ions Changing Charge State in the LEIR Ring

    CERN Document Server

    Pasternak, Jaroslaw; Carli, Christian; Chanel, Michel; Mahner, Edgar

    2005-01-01

    Avalanche-like pressure rise and an associated decrease of the beam life-time, caused by (i) beam loss due to charge exchange interactions with rest gas molecules and (ii) electron capture from the electron beam of the electron cooler and (iii) ion impact induced outgassing, is a potential limitation for heavy ion accelerators. The vacuum system of the LEIR ring as to be upgraded to reach the dynamical vacuum pressure in the low 10-12 Torr range necessary to reach design performance. A collimation system to intercept lost ions by absorber blocks made of low beam-induced outgassing material will be installed. This paper reviews the collimation scheme and simulations of beam loss patterns around the ring.

  15. Current density waves in open mesoscopic rings driven by time-periodic magnetic fluxes

    International Nuclear Information System (INIS)

    Yan Conghua; Wei Lianfu

    2010-01-01

    Quantum coherent transport through open mesoscopic Aharonov-Bohm rings (driven by static fluxes) have been studied extensively. Here, by using quantum waveguide theory and the Floquet theorem we investigate the quantum transport of electrons along an open mesoscopic ring threaded by a time-periodic magnetic flux. We predicate that current density waves could be excited along such an open ring. As a consequence, a net current could be generated along the lead with only one reservoir, if the lead additionally connects to such a normal-metal loop driven by the time-dependent flux. These phenomena could be explained by photon-assisted processes, due to the interaction between the transported electrons and the applied oscillating external fields. We also discuss how the time-average currents (along the ring and the lead) depend on the amplitude and frequency of the applied oscillating fluxes.

  16. Electromagnetic pulse-driven spin-dependent currents in semiconductor quantum rings.

    Science.gov (United States)

    Zhu, Zhen-Gang; Berakdar, Jamal

    2009-04-08

    We investigate the non-equilibrium charge and spin-dependent currents in a quantum ring with a Rashba spin-orbit interaction (SOI) driven by two asymmetric picosecond electromagnetic pulses. The equilibrium persistent charge and persistent spin-dependent currents are investigated as well. It is shown that the dynamical charge and the dynamical spin-dependent currents vary smoothly with a static external magnetic flux and the SOI provides a SU(2) effective flux that changes the phases of the dynamic charge and the dynamic spin-dependent currents. The period of the oscillation of the total charge current with the delay time between the pulses is larger in a quantum ring with a larger radius. The parameters of the pulse fields control to a certain extent the total charge and the total spin-dependent currents. The calculations are applicable to nanometre rings fabricated in heterojunctions of III-V and II-VI semiconductors containing several hundreds of electrons.

  17. Quantum rings in magnetic fields and spin current generation.

    Science.gov (United States)

    Cini, Michele; Bellucci, Stefano

    2014-04-09

    We propose three different mechanisms for pumping spin-polarized currents in a ballistic circuit using a time-dependent magnetic field acting on an asymmetrically connected quantum ring at half filling. The first mechanism works thanks to a rotating magnetic field and produces an alternating current with a partial spin polarization. The second mechanism works by rotating the ring in a constant field; like the former case, it produces an alternating charge current, but the spin current is dc. Both methods do not require a spin-orbit interaction to achieve the polarized current, but the rotating ring could be used to measure the spin-orbit interaction in the ring using characteristic oscillations. On the other hand, the last mechanism that we propose depends on the spin-orbit interaction in an essential way, and requires a time-dependent magnetic field in the plane of the ring. This arrangement can be designed to pump a purely spin current. The absence of a charge current is demonstrated analytically. Moreover, a simple formula for the current is derived and compared with the numerical results.

  18. Spin-dependent heat and thermoelectric currents in a Rashba ring coupled to a photon cavity

    Science.gov (United States)

    Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2018-01-01

    Spin-dependent heat and thermoelectric currents in a quantum ring with Rashba spin-orbit interaction placed in a photon cavity are theoretically calculated. The quantum ring is coupled to two external leads with different temperatures. In a resonant regime, with the ring structure in resonance with the photon field, the heat and the thermoelectric currents can be controlled by the Rashba spin-orbit interaction. The heat current is suppressed in the presence of the photon field due to contribution of the two-electron and photon replica states to the transport while the thermoelectric current is not sensitive to changes in parameters of the photon field. Our study opens a possibility to use the proposed interferometric device as a tunable heat current generator in the cavity photon field.

  19. Cryogenic Current Comparator for Storage Rings and Accelerators

    OpenAIRE

    Geithner, Rene; Fernandes, Miguel; Kurian, Febin; Neubert, Ralf; Reeg, Hansjörg; Schwickert, Marcus; Seidel, Paul; Sieber, Thomas; Stöhlker, Thomas

    2016-01-01

    A Cryogenic Current Comparator (CCC) was developed for a non-destructive, highly sensitive monitoring of nA beams at the planned FAIR accelerator facility at GSI. The sensor part of the CCC was optimized for lowest possible noise-limited current resolution in combination with a high system bandwidth of about 200 kHz. It is foreseen to install the CCC inside the CRYRING, which will act as a well-suited test bench for further optimization of the CCC performance and the cryostat. In the meantime...

  20. Inductive fault current limiter based on multiple superconducting rings of small diameter

    International Nuclear Information System (INIS)

    Osorio, M R; Cabo, L; Veira, J A; Vidal, F

    2004-01-01

    We present a fault current limiter prototype based on the use of a secondary comprised of an array of magnetic cores of small sections, each one of them with several superconducting rings. The main advantage of this configuration is that it is easier to make small diameter superconducting rings which, in addition, are more homogeneous and allow better refrigeration. We then present detailed measurements that show that, in addition to these advantages, this prototype offers the same limitation performances than when using a unique core and a superconducting ring with an equivalent area as the array of small section cores

  1. Plasma confinement in a magnetic field of the internal ring current

    International Nuclear Information System (INIS)

    Shafranov, Vitaly; Popovich, Paul; Samitov, Marat

    2000-01-01

    Plasma confinement in compact region surrounding an internal ring current is considered. As the limiting case of large aspect ratio system the cylindrical plasma is considered initially. Analysis of the cylindrical tubular plasma equilibrium and stability against the most dangerous flute (m=0) and kink (m=1) modes revealed the possibility of the MHD stable plasma confined by magnetic field of the internal rod current, with rather peaked plasma pressure and maximal local beta β(γ)=0.4. In case of the toroidal internal ring system an additional external magnetic field creates the boundary separatrix witch limits the plasma volume. The dependence of the plasma pressure profiles, marginally stable with respect to the flute modes, from the shape of the external plasma boundary (separatrix) in such kind closed toroidal systems is investigated. The internal ring system with circular poloidal magnetic mirror, where the ring supports could be placed, is proposed. (author)

  2. Experiments with highly-charged heavy-ions performed at the storage ring ESR

    International Nuclear Information System (INIS)

    Mokler, P.H.

    1992-01-01

    The new heavy ion accelerator facility SIS/ESR was inaugurated in April 1990. During 1991 the experimental storage ring, ESR, has been commissioned. Highly-charged heavy ions from O 8+ up to Bi 82+ were successfully accumulated, cooled, and stored in the ring. Now all highly-charged, heavy ions can be provided for experiments at comfortable storage times and at energies roughly between 100 and 500 MeV/u. A report on the achievements and on the first experimental results will be given. For the experiments, special emphasis is put on capture processes in the electron cooler, i.e. on radiative and dielectronic recombination processes as well as on capture events of bound target electrons from a gas jet. In this case, the capture leads either directly (REC) or by cascading to X-ray emission, which is also exploited for a precision spectroscopy of the structure of the heaviest ions. Another exciting topic is the radioactive decay of highly charged ions: For instance the β-decay into bound atomic states, which is not possible for neutral atoms, was studied for stored naked Dy ions. (orig.)

  3. First current density measurements in the ring current region using simultaneous multi-spacecraft CLUSTER-FGM data

    Directory of Open Access Journals (Sweden)

    C. Vallat

    2005-07-01

    Full Text Available The inner magnetosphere's current mapping is one of the key elements for current loop closure inside the entire magnetosphere. A method for directly computing the current is the multi-spacecraft curlometer technique, which is based on the application of Maxwell-Ampère's law. This requires the use of four-point magnetic field high resolution measurements. The FGM experiment on board the four Cluster spacecraft allows, for the first time, an instantaneous calculation of the magnetic field gradients and thus a measurement of the local current density. This technique requires, however, a careful study concerning all the factors that can affect the accuracy of the J estimate, such as the tetrahedral geometry of the four spacecraft, or the size and orientation of the current structure sampled. The first part of this paper is thus providing a detailed analysis of the method accuracy, and points out the limitations of this technique in the region of interest. The second part is an analysis of the ring current region, which reveals, for the first time, the large latitudinal extent of the ring current, for all magnetic activity levels, as well as the latitudinal evolution of the perpendicular (and parallel components of the current along the diffuse auroral zone. Our analysis also points out the sharp transition between two distinct plasma regions, with the existence of high diamagnetic currents at the interface, as well as the filamentation of the current inside the inner plasma sheet. A statistical study over multiple perigee passes of Cluster (at about 4 RE from the Earth reveals the azimuthal extent of the partial ring current. It also reveals that, at these distances and all along the evening sector, there isn't necessarily a strong dependence of the local current density value on the magnetic activity level. This is a direct consequence of the ring current morphology evolution, as well as the relative

  4. Ring current models for acetylene and ethylene molecules

    International Nuclear Information System (INIS)

    Pelloni, Stefano; Lazzeretti, Paolo

    2009-01-01

    Spatial models of the current density vector field, induced in the electronic cloud of the acetylene and ethylene molecules by a uniform, time-independent magnetic field, are discussed in terms of topological stagnation graphs and three-dimensional streamline plots. The models are validated by documenting their ability to explain magnetic susceptibility and nuclear magnetic shieldings of carbon and hydrogen via related shielding density maps

  5. Analogue Between Dynamic Hamiltonian-Operators of a Mesoscopic Ring Carrying Persistent Current and a Josephson Junction

    International Nuclear Information System (INIS)

    Fan Hongyi; Wang Jisuo

    2006-01-01

    By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system.

  6. Design considerations for a digital feedback system to control self-bunching in ion-storage rings

    Directory of Open Access Journals (Sweden)

    V. Ziemann

    2001-04-01

    Full Text Available We discuss the feasibility of a digital feedback system to cure self-bunching of the electron-cooled coasting ion beam in ion-storage rings such as CELSIUS [S. Holm, A. Johansson, S. Kullander, and D. Reistad, Phys. Scr. 34, 513–532 (1986]. Such a system is based on a fast digital filter that acts as a tunable artificial wake potential. It may also aid stable operation of accumulator rings for future spallation neutron sources or heavy ion rings used for inertial fusion energy production.

  7. The plasmasheet H+ and O+ contribution on the storm time ring current

    Science.gov (United States)

    Mouikis, C.; Bingham, S.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

    2015-12-01

    The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes and Cluster observations to determine the contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. Using the Volland-Stern model with a dipole magnetic field together with the identification of the observed energy cutoffs in the particle spectra, we specify the pressure contributed by H+ and O+ populations that are on open drift paths vs. the pressure contributed by the trapped populations, for different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L~2 and their pressure compares to the local magnetic field pressure as deep as L~3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current.

  8. On the physics of ion ring generation for the stabilization of FRX discharges. Final report

    International Nuclear Information System (INIS)

    Fleischmann, H.

    1995-01-01

    As envisioned in the respective proposals, the author's work over the final periods of this contract centered on experimental and related theoretical investigations of the physics of the generation of ion rings which might be used for a tilt stabilization of FRX rings, with experiments centering around the new MICE equipment constructed during the earlier parts of the work. In particular, the work mainly consisted of the following: (i) investigations concerning the operation of the ion beam driver constructed earlier, especially of the magnetically insulated ion diode and possible improvements of that diode; (ii) theoretical analyses on the propagation and neutralization of the ion beam during its injection into the confinement tank; and (iii) experimental investigations on the physics of ion beam injection and ring formation in the MICE device; in these latter experiments very significant discrepancies of various observed data and those predicted from single-particle orbit calculations were found. Unfortunately, the work could not be completed due to stop in funding, but a semiquantitative analysis of these discrepancies indicated insufficient space charge neutralization of the ion beam in the tank and/or charge-exchange effects in the diode are considered the most likely reasons. In contrast to claims by its authors, a similar discrepancy also was found in the published data of the earlier IREX experiment. The results of their investigations, which together with the design and construction of the equipment provided the basis for two PhD theses, will be briefly described in this report; the full details can be obtained from the two theses

  9. Colliding or co-rotating ion beams in storage rings for EDM search

    International Nuclear Information System (INIS)

    Koop, I A

    2015-01-01

    A new approach to search for and measure the electric dipole moment (EDM) of the proton, deuteron and some other light nuclei is presented. The idea of the method is to store two ion beams, circulating with different velocities, in a storage ring with crossed electric and magnetic guiding fields. One beam is polarized and its EDM is measured using the so-called ‘frozen spin’ method. The second beam, which is unpolarized, is used as a co-magnetometer, sensitive to the radial component of the ring’s magnetic field. The particle’s magnetic dipole moment (MDM) couples to the radial magnetic field and mimics the EDM signal. Measuring the relative vertical orbit separation of the two beams, caused by the presence of the radial magnetic field, one can control the unwanted MDM spin precession. Examples of the parameters for EDM storage rings for protons and other species of ions are presented. The use of crossed electric and magnetic fields helps to reduce the size of the ring by a factor of 10–20. We show that the bending radius of such an EDM storage ring could be about 2–3 m. Finally, a new method of increasing the spin coherence time, the so-called ‘spin wheel’, is proposed and its applicability to the EDM search is discussed. (paper)

  10. Physics with colder molecular ions: The Heidelberg Cryogenic Storage Ring CSR

    International Nuclear Information System (INIS)

    Zajfman, D; Wolf, A; Schwalm, D; Orlov, D A; Grieser, M; Hahn, R von; Welsch, C P; Lopez-Urrutia, J R Crespo; Schroeter, C D; Urbain, X; Ullrich, J

    2005-01-01

    A novel cryogenic electrostatic storage ring is planned to be built at the Max-Planck Institute for Nuclear Physics in Heidelberg. The machine is expected to operate at low temperatures (∼2K) and to store beams with kinetic energies between 20 to 300 keV. An electron target based on cooled photocathode technology will serve as a major tool for the study of reactions between molecular ions and electrons. Moreover, atomic beams can be merged and crossed with the stored ion beams allowing for atom molecular-ion collision studies at very low up to high relative energies. The proposed experimental program, centered around the physics of cold molecular ions, is shortly outlined

  11. Space charge and working point studies in the CERN Low Energy Ion Ring

    CERN Document Server

    Huschauer, A; Hancock, S; Kain, V

    2017-01-01

    The Low Energy Ion Ring (LEIR) is at the heart ofCERN’s heavy ion physics programme and was designed toprovide the high phase space densities required by the exper-iments at the Large Hadron Collider (LHC). LEIR is the firstsynchrotron of the LHC ion injector chain and it receives aquasi-continuous pulse of lead ions (Pb54+) from Linac3, ex-ploiting a sophisticated multi-turn injection scheme in bothtransverse and longitudinal planes. Seven of these pulses areinjected and accumulated, which requires continuous elec-tron cooling (EC) at low energy to decrease the phase spacevolume of the circulating beam in between two injections.Subsequently, the coasting beam is adiabatically capturedin two bunches, which are then accelerated and extractedtowards the Proton Synchrotron (PS). Figure 1 shows theLEIR magnetic cycle and the different steps required forbeam production.

  12. Phase locked multiple rings in the radiation pressure ion acceleration process

    Science.gov (United States)

    Wan, Y.; Hua, J. F.; Pai, C.-H.; Li, F.; Wu, Y. P.; Lu, W.; Zhang, C. J.; Xu, X. L.; Joshi, C.; Mori, W. B.

    2018-04-01

    Laser contrast plays a crucial role for obtaining high quality ion beams in the radiation pressure ion acceleration (RPA) process. Through one- and two-dimensional particle-in-cell (PIC) simulations, we show that a plasma with a bi-peak density profile can be produced from a thin foil on the effects of a picosecond prepulse, and it can then lead to distinctive modulations in the ion phase space (phase locked double rings) when the main pulse interacts with the target. These fascinating ion dynamics are mainly due to the trapping effect from the ponderomotive potential well of a formed moving standing wave (i.e. the interference between the incoming pulse and the pulse reflected by a slowly moving surface) at nodes, quite different from the standard RPA process. A theoretical model is derived to explain the underlying mechanism, and good agreements have been achieved with PIC simulations.

  13. White-light laser cooling of ions in a storage ring

    International Nuclear Information System (INIS)

    Calabrese, R.; Guidi, V.; Lenisa, P.; Grimm, R.; Miesner, H.J.; Mariotti, E.; Siena Univ.; Moi, L.; Siena Univ.

    1996-01-01

    We propose the use of a white laser for laser cooling of ions in a storage ring. The use of a broad-band laser provides a radiation pressure force with wide velocity capture range and high magnitude, which is promising to improve the performance of both longitudinal and indirect transverse cooling. This wide-range force could also be suitable for direct transverse cooling of low-density beams. (orig.)

  14. Electron cooling of a bunched ion beam in a storage ring

    Science.gov (United States)

    Zhao, He; Mao, Lijun; Yang, Jiancheng; Xia, Jiawen; Yang, Xiaodong; Li, Jie; Tang, Meitang; Shen, Guodong; Ma, Xiaoming; Wu, Bo; Wang, Geng; Ruan, Shuang; Wang, Kedong; Dong, Ziqiang

    2018-02-01

    A combination of electron cooling and rf system is an effective method to compress the beam bunch length in storage rings. A simulation code based on multiparticle tracking was developed to calculate the bunched ion beam cooling process, in which the electron cooling, intrabeam scattering (IBS), ion beam space-charge field, transverse and synchrotron motion are considered. Meanwhile, bunched ion beam cooling experiments have been carried out in the main cooling storage ring (CSRm) of the Heavy Ion Research Facility in Lanzhou, to investigate the minimum bunch length obtained by the cooling method, and study the dependence of the minimum bunch length on beam and machine parameters. The experiments show comparable results to those from simulation. Based on these simulations and experiments, we established an analytical model to describe the limitation of the bunch length of the cooled ion beam. It is observed that the IBS effect is dominant for low intensity beams, and the space-charge effect is much more important for high intensity beams. Moreover, the particles will not be bunched for much higher intensity beam. The experimental results in CSRm show a good agreement with the analytical model in the IBS dominated regime. The simulation work offers us comparable results to those from the analytical model both in IBS dominated and space-charge dominated regimes.

  15. Calculations of toroidal EXTRAP equilibria for different toroidal ring current configurations

    International Nuclear Information System (INIS)

    Drake, J.R.; Scheffel, J.

    1985-12-01

    EXTRAP is a concept in which a pure Z-pinch is generated along the axis of an octupole field. Experiments in a linear as well as in a sector geometry have demonstrated that the pinch becomes stable against instabilities for many Alfven times. The octupole field in EXTRAP is produced by four, external, current-carrying rings. In the toroidal geometry these rings must be supplemented by additional rings to compensate for the plasma loop force and transformer core leakage flux. Equilibrium studies are carried out for two basically ring designs. The studies are based on numerical equilibrium copmputations using the GOYA code. Sensitivity of the equilibrium to technical imperfections is also analyzed. (author)

  16. Persistent current of relativistic electrons on a Dirac ring in presence of impurities

    KAUST Repository

    Ghosh, Sumit; Saha, Arijit

    2014-01-01

    We study the behaviour of persistent current of relativistic electrons on a one dimensional ring in presence of attractive/repulsive scattering potentials. In particular, we investigate the persistent current in accordance with the strength as well as the number of the scattering potential. We find that in presence of single scatterer the persistent current becomes smaller in magnitude than the scattering free scenario. This behaviour is similar to the non-relativistic case. Even for a very strong scattering potential, finite amount of persistent current remains for a relativistic ring. In presence of multiple scatterer we observe that the persistent current is maximum when the scatterers are placed uniformly compared to the current averaged over random configurations. However if we increase the number of scatterers, we find that the random averaged current increases with the number of scatterers. The latter behaviour is in contrast to the non-relativistic case. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

  17. Persistent current of relativistic electrons on a Dirac ring in presence of impurities

    KAUST Repository

    Ghosh, Sumit

    2014-08-01

    We study the behaviour of persistent current of relativistic electrons on a one dimensional ring in presence of attractive/repulsive scattering potentials. In particular, we investigate the persistent current in accordance with the strength as well as the number of the scattering potential. We find that in presence of single scatterer the persistent current becomes smaller in magnitude than the scattering free scenario. This behaviour is similar to the non-relativistic case. Even for a very strong scattering potential, finite amount of persistent current remains for a relativistic ring. In presence of multiple scatterer we observe that the persistent current is maximum when the scatterers are placed uniformly compared to the current averaged over random configurations. However if we increase the number of scatterers, we find that the random averaged current increases with the number of scatterers. The latter behaviour is in contrast to the non-relativistic case. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

  18. Structure of very heavy few-electron ions - new results from the heavy ion storage ring, ESR

    International Nuclear Information System (INIS)

    Mokler, P.H.; Stoehlker, T.; Kozhuharov, C.; Moshammer, R.; Rymuza, P.; Bosch, F.; Kandler, T.

    1993-08-01

    The heavy ion synchrotron/storage ring facility at GSI, SIS/ESR, provides intense beams of cooled, highly-charged ions up to naked uranium (U 92+ ). By electron capture during ion-atom collisions in the gas target of the ESR or by recombination at ion-electron encounters in the ''electron cooler'' excited states are populated. The detailed structure of very heavy one-, two- and three-electron ions is studied. The different mechanisms leading to the excited states are described, as well as the new experimental tools now available for a detailed spectroscopy of these interesting systems. Special emphasis is given to X-ray transitions to the groundstates in H- and He-like systems. For the heaviest species the groundstate Lambshift can now be probed on an accuracy level of better than 10% using solid-state X-ray detectors. Applying dispersive X-ray analyzing techniques, this accuracy will certainly be improved in future. However, utilizing the dielectronic resonances for a spectroscopy, the structure in Li-like heavy ions can already be probed now on the sub eV level. (orig.)

  19. Terrestrial ring current - from in situ measurements to global images using energetic neutral atoms

    International Nuclear Information System (INIS)

    Roelof, E.C.; Williams, D.J.

    1988-01-01

    Electrical currents flowing in the equatorial magnetosphere, first inferred from ground-based magnetic disturbances, are carried by trapped energetic ions. Spacecraft measurements have determined the spectrum and composition of those currents, and the newly developed technique of energetic-neutral-atom imaging allows the global dynamics of that entire ion population to be viewed from a single spacecraft. 71 references

  20. The role of substorms in the formation of the ring current

    International Nuclear Information System (INIS)

    Rostoker, G.

    1996-01-01

    It has long been recognized that the formation of the terrestrial ring current is accompanied by strong substorm expansive phase activity in the auroral oval. While large amplitude substorm activity seems to be a prerequisite for ring current formation to take place, it has long been puzzling as to why some large amplitude substorm activity in the auroral oval is not associated with significant ring current development. In this paper I shall outline the basis for the renovated boundary layer dynamics model of magnetospheric substorms showing how the onset of the substorm expansive phase can be associated with a sudden decrease in shielding space charge in the region of the near-Earth plasma sheet threaded by Region 2 field-aligned currents. I shall suggest that an episode of sufficiently large southward IMF lasting over a sufficiently lengthy period of time can lead to a sequence of substorm expansive phases, each one being initiated closer to the Earth than the previous one. Each expansive phase is attributed to a sudden decrease in radially localized cross-tail current (viz. a decrease in shielding space charge) and with each onset the inner edge of the plasma sheet moves inward. The inductive electric field associated with each crosstail current decrease is responsible for the acceleration of already energetic particles to energies of significance for ring current formation. Only when the inner edge of the crosstail current is sufficiently close to the Earth do the acceleration processes associated with substorm onset produce a long lived ring current. copyright 1996 American Institute of Physics

  1. Radial profile of pressure in a storm ring current as a function of D st

    Science.gov (United States)

    Kovtyukh, A. S.

    2010-06-01

    Using satellite data obtained near the equatorial plane during 12 magnetic storms with amplitudes from -61 down to -422 nT, the dependences of maximum in L-profile of pressure ( L m) of the ring current (RC) on the current value of D st are constructed, and their analytical approximations are derived. It is established that function L m( D st ) is steeper on the phase of recovery than during the storm’s main phase. The form of the outer edge of experimental radial profiles of RC pressure is studied, and it is demonstrated to correspond to exponential growth of the total energy of RC particles on a given L shell with decreasing L. It is shown that during the storms’ main phase the ratio of plasma and magnetic field pressures at the RC maximum does not practically depend on the storm strength and L m value. This fact reflects resistance of the Earth’s magnetic field to RC expansion, and testifies that during storms the possibilities of injection to small L are limited for RC particles. During the storms’ recovery phase this ratio quickly increases with increasing L m, which reflects an increased fraction of plasma in the total pressure balance. It is demonstrated that function L m( D st ) is derived for the main phase of storms from the equations of drift motion of RC ions in electrical and magnetic fields, reflecting the dipole character of magnetic field and scale invariance of the pattern of particle convection near the RC maximum. For the recovery phase it is obtained from the Dessler-Parker-Sckopke relationship. The obtained regularities allow one to judge about the radial profile of RC pressure from ground-based magnetic measurements (data on the D st variation).

  2. Current Progress of Capacitive Deionization for Removal of Pollutant Ions

    Science.gov (United States)

    Gaikwad, Mahendra S.; Balomajumder, Chandrajit

    2016-08-01

    A mini review of a recently developing water purification technology capacitive deionization (CDI) applied for removal of pollutant ions is provided. The current progress of CDI for removal of different pollutant ions such as arsenic, fluoride, boron, phosphate, lithium, copper, cadmium, ferric, and nitrate ions is presented. This paper aims at motivating new research opportunities in capacitive deionization technology for removal of pollutant ions from polluted water.

  3. Ion current reduction in pinched electron beam diodes

    International Nuclear Information System (INIS)

    Quintenz, J.P.; Poukey, J.W.

    1977-01-01

    A new version of a particle-in-cell diode code has been written which permits the accurate treatment of higher-current diodes with greater physical dimensions. Using this code, we have studied ways to reduce the ion current in large-aspect-ratio pinched electron beam diodes. In particular, we find that allowing the ions to reflex in such diodes lowers the ion to electron current ratio considerably. In a 3-MV R/d=24 case this ratio was lowered by a factor of 6--8 compared with the corresponding nonreflexing-ion diode, while still producing a superpinched electron beam

  4. Effects of the Ring Current on ULF Waves in the Magnetosphere

    Directory of Open Access Journals (Sweden)

    Khan-Hyuk Kim

    1994-06-01

    Full Text Available A three-dimensional box model has been developed to study the MHD wave coupling in the magnetosphere. In this model, the effects of the ring current are included by assuming the pressure gradients in the MHD equations. It is found that the axisymmetric ring current may play an important role in producing spectral noises in compressional waves, while field line resonances have no such disturbances. These results may explain the current observational characteristics that compressional cavity modes hardly appear in the satellite experiment, while field line resonances often occur. Our numerical results also suggest that any discrete spectral peaks such as the global cavity modes can hardly occur where the pressure distribution of the ring current becomes important. The continuous band of transverse waves is found to be unperturbed until the ring current becomes significantly asymmetric with respect to the dipole axis. In addition, our results in the absence of the pressure gradient are found to be consistent with the previous results from the box-like and dipole models.

  5. Dynamics of Ring Current and Electric Fields in the Inner Magnetosphere During Disturbed Periods: CRCM-BATS-R-US Coupled Model

    Science.gov (United States)

    Buzulukova, N.; Fok, M.-C.; Pulkkinen, A.; Kuznetsova, M.; Moore, T. E.; Glocer, A.; Brandt, P. C.; Toth, G.; Rastaetter, L.

    2010-01-01

    We present simulation results from a one-way coupled global MHD model (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and kinetic ring current models (Comprehensive Ring Current Model, CRCM, and Fok Ring Current, FokRC). The BATS-R-US provides the CRCM/FokRC with magnetic field information and plasma density/temperature at the polar CRCM/FokRC boundary. The CRCM uses an electric potential from the BATS-R-US ionospheric solver at the polar CRCM boundary in order to calculate the electric field pattern consistent with the CRCM pressure distribution. The FokRC electric field potential is taken from BATS-R-US ionospheric solver everywhere in the modeled region, and the effect of Region II currents is neglected. We show that for an idealized case with southward-northward-southward Bz IMF turning, CRCM-BATS-R-US reproduces well known features of inner magnetosphere electrodynamics: strong/weak convection under the southward/northward Bz; electric field shielding/overshielding/penetration effects; an injection during the substorm development; Subauroral Ion Drift or Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore, we find for the idealized case that SAID/PJ forms during the substorm growth phase, and that substorm injection has its own structure of field-aligned currents which resembles a substorm current wedge. For an actual event (12 August 2000 storm), we calculate ENA emissions and compare with Imager for Magnetopause-to-Aurora Global Exploration/High Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the global morphology of ring current and the fine structure of ring current injection. The FokRC-BATS-R-US shows the effect of a realistic description of Region II currents in ring current-MHD coupled models.

  6. Three-Step Buildup of the 17 March 2015 Storm Ring Current: Implication for the Cause of the Unexpected Storm Intensification

    Science.gov (United States)

    Keika, Kunihiro; Seki, Kanako; Nosé, Masahito; Miyoshi, Yoshizumi; Lanzerotti, Louis J.; Mitchell, Donald G.; Gkioulidou, Matina; Manweiler, Jerry W.

    2018-01-01

    We examine the spatiotemporal variations of the energy density and the energy spectral evolution of energetic ions in the inner magnetosphere during the main phase of the 17 March 2015 storm, using data from the RBSPICE and EMFISIS instruments onboard Van Allen Probes. The storm developed in response to two southward IMF intervals separated by about 3 h. In contrast to two steps seen in the Dst/SYM-H index, the ring current ion population evolved in three steps: the first subphase was apparently caused by the earlier southward IMF, and the subsequent subphases occurred during the later southward IMF period. Ion energy ranges that contribute to the ring current differed between the three subphases. We suggest that the spectral evolution resulted from the penetration of different plasma sheet populations. The ring current buildup during the first subphase was caused by the penetration of a relatively low-energy population that had existed in the plasma sheet during a prolonged prestorm northward IMF interval. The deeper penetration of the lower-energy population was responsible for the second subphase. The third subphase, where the storm was unexpectedly intensified to a Dst/SYM-H level of population. We attribute the hot, dense population to the entry of hot, dense solar wind into the plasma sheet and/or ion heating/acceleration in the near-Earth plasma sheet associated with magnetotail activity such as reconnection and dipolarization.

  7. Bootstrap current of fast ions in neutral beam injection heating

    International Nuclear Information System (INIS)

    Huang Qianhong; Gong Xueyu; Yang Lei; Li Xinxia; Lu Xingqiang; Yu Jun

    2012-01-01

    The bootstrap current of fast ions produced by the neutral beam injection is investigated in a large aspect ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are figured out. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current considered, the net current density obviously decreases due to electron return current, at the same time the peak of current moves towards the centre plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the neutral beam injection but also on the ratio of the velocity of fast ions to the critical velocity: the value of net current is small for the neutral beam parallel injection but increases multipliedly for perpendicular injection, and increases with beam energy increasing. (authors)

  8. Enhanced Schottky signals from electron-cooled, coasting beams in a heavy-ion storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, C., E-mail: claude.krantz@mpi-hd.mpg.d [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Blaum, K.; Grieser, M. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Litvinov, Yu.A. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany); Repnow, R.; Wolf, A. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

    2011-02-11

    Measurements at the Test Storage Ring of the Max-Planck-Institut fuer Kernphysik in Heidelberg (Germany) have shown that the signal amplitude induced in a Schottky-noise pickup electrode by a coasting electron-cooled ion beam can be greatly enhanced by exposure of the latter to a perturbing radiofrequency signal which is detuned from the true beam revolution frequency. The centre frequencies obtained from harmonic analysis of the observed pickup signal closely follow those imposed on the ions by the electron cooling force. The phenomenon can be exploited to measure the true revolution frequency of ion beams of very low intensity, whose pure Schottky noise is too weak to be measurable under normal circumstances.

  9. A high current high frequency ions gun

    International Nuclear Information System (INIS)

    Coutant, J.; Prevot, F.; Vienet, R.

    1959-01-01

    A 10 mA protons gun has been developed for different purposes. The first part of the report studies the plasma production with a RF electromagnetic field. Then the ion extraction process is analysed with particular reference to space charge phenomena. The last part describes a three electrode electrostatic lens which focusses the beam. (author) [fr

  10. On the Stability of Pick-up Ion Ring Distributions in the Outer Heliosheath

    Science.gov (United States)

    Summerlin, Errol J.; Viñas, Adolfo F.; Moore, Thomas E.; Christian, Eric R.; Cooper, John F.

    2014-10-01

    The "secondary energetic neutral atom (ENA)" hypothesis for the ribbon feature observed by the Interstellar Boundary Explorer (IBEX) posits that the neutral component of the solar wind continues beyond the heliopause and charge exchanges with interstellar ions in the Outer Heliosheath (OHS). This creates pick-up ions that gyrate about the draped interstellar magnetic field (ISMF) lines at pitch angles near 90° on the locus where the ISMF lies tangential to the heliopause and perpendicular to the heliocentric radial direction. This location closely coincides with the location of the ribbon feature according to the prevailing inferences of the ISMF orientation and draping. The locally gyrating ions undergo additional charge exchange and escape as free-flying neutral atoms, many of which travel back toward the inner solar system and are imaged by IBEX as a ribbon tracing out the locus described above. For this mechanism to succeed, the pick-up ions must diffuse in pitch angle slowly enough to permit secondary charge exchange before their pitch angle distribution substantially broadens away from 90°. Previous work using linear Vlasov dispersion analysis of parallel propagating waves has suggested that the ring distribution in the OHS is highly unstable, which, if true, would make the secondary ENA hypothesis incapable of rendering the observed ribbon. In this paper, we extend this earlier work to more realistic ring distribution functions. We find that, at the low densities necessary to produce the observed IBEX ribbon via the secondary ENA hypothesis, growth rates are highly sensitive to the temperature of the beam and that even very modest temperatures of the ring beam corresponding to beam widths of distributions necessary to produce the observed IBEX ENA flux via the secondary ENA hypothesis will be unstable to their own self-generated turbulence.

  11. On the stability of pick-up ion ring distributions in the outer heliosheath

    International Nuclear Information System (INIS)

    Summerlin, Errol J.; Viñas, Adolfo F.; Moore, Thomas E.; Christian, Eric R.; Cooper, John F.

    2014-01-01

    The 'secondary energetic neutral atom (ENA)' hypothesis for the ribbon feature observed by the Interstellar Boundary Explorer (IBEX) posits that the neutral component of the solar wind continues beyond the heliopause and charge exchanges with interstellar ions in the Outer Heliosheath (OHS). This creates pick-up ions that gyrate about the draped interstellar magnetic field (ISMF) lines at pitch angles near 90° on the locus where the ISMF lies tangential to the heliopause and perpendicular to the heliocentric radial direction. This location closely coincides with the location of the ribbon feature according to the prevailing inferences of the ISMF orientation and draping. The locally gyrating ions undergo additional charge exchange and escape as free-flying neutral atoms, many of which travel back toward the inner solar system and are imaged by IBEX as a ribbon tracing out the locus described above. For this mechanism to succeed, the pick-up ions must diffuse in pitch angle slowly enough to permit secondary charge exchange before their pitch angle distribution substantially broadens away from 90°. Previous work using linear Vlasov dispersion analysis of parallel propagating waves has suggested that the ring distribution in the OHS is highly unstable, which, if true, would make the secondary ENA hypothesis incapable of rendering the observed ribbon. In this paper, we extend this earlier work to more realistic ring distribution functions. We find that, at the low densities necessary to produce the observed IBEX ribbon via the secondary ENA hypothesis, growth rates are highly sensitive to the temperature of the beam and that even very modest temperatures of the ring beam corresponding to beam widths of <1° are sufficient to damp the self-generated waves associated with the ring beam. Thus, at least from the perspective of linear Vlasov dispersion analysis of parallel propagating waves, there is no reason to expect that the ring distributions necessary to

  12. The emittance of high current heavy ion beams

    International Nuclear Information System (INIS)

    White, N.R.; Devaney, A.S.

    1989-01-01

    Ion implantation is the main application for high current heavy ion beams. Transfer ratio is defined as the ratio of the total ion current leaving the ion source to the current delivered to the endstation. This ratio is monitored and logged and its importance is explained. It is also affected by other factors, such as the isotopic and molecular composition of the total ion beam. The transfer ratio reveals the fraction of ions which are intercepted by parts of the beamline system. The effects of these ions are discussed in two categories: processing purity and reliability. In discussing the emittance of ribbon beams, the two orthogonal planes are usually considered separately. Longitudinal emittance is determined by slot length and by plasma ion temperature. It has already been revealed that the longitudinal divergence of the beams from BF3 is perhaps double that of the beam from arsenic vapour or argon, at the same total perveance from the ion source. This poses the question: why is the ion temperature higher for BF3 than for As or Ar? The transverse emittance is in practical terms dominated by the divergence. It is the most fruitful area for improvement in most real-world systems. There is an intrinsic divergence arising from initial ion energies within the plasma, and there is emittance growth that can occur as a result of aberration in the beam extraction optics. (N.K.)

  13. Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    1994-06-01

    Full Text Available The relationship between the auroral electrojet indices (AE and the ring current magnetic field (DR was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'. To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE' which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence of saturation for minimum (maximum AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF Bz variations than the symmetric ring current. ASY increases (decreases faster during the main phase (the recovery phase than DR. The magnetic field decay at low latitudes in the

  14. Bootstrap current of fast ions in neutral beam injection heating

    International Nuclear Information System (INIS)

    Huang Qianhong; Gong Xueyu; Li Xinxia; Yu Jun

    2012-01-01

    The bootstrap current of fast ions produced by neutral beam injection (NBI) is investigated in a large-aspect-ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are reported. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current taken into consideration, the net current density obviously decreases; at the same time, the peak of the current moves towards the central plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the NBI but also on the ratio of the velocity of fast ions to the critical velocity: the value of the net current is small for neutral beam parallel injection, but increases severalfold for perpendicular injection, and increases with increasing beam energy. (paper)

  15. Current ideas on ion-atom collisions

    International Nuclear Information System (INIS)

    Hansteen, J.M.

    1975-09-01

    A survey is given of recent developments in the understanding of ion-atom collisions, with particular emphasis on processes leading to ion-induced X-rays. The inner-shell Coulomb ionization phenomena are discussed at some length, with stress on the near-quantitative picture that appears to emerge from simple-minded models. The phenomenon of Pauli excitations and the formation of quasi-molecules leading to united atom phenomena are qualitatively reviewed together with a brief mention of target recoil effects and electron capture processes. Selected background phenomena of importance in interpreting experiments are touched upon, such as various types of bremsstrahlung production. Implications of the recently-discovered interplay between Coulomb-induced processes and united atom phenomena are especially mentioned. It is suggested that this branch of collision physics is now (1975) reaching a point where new notions and more advanced and unifying models are greatly needed. (auth)

  16. Chronicle of ion-current instabilities: old and new

    International Nuclear Information System (INIS)

    Landau, R.W.

    1975-07-01

    For counter-streaming ion currents along a uniform magnetic field, a purely growing instability exists with a growth rate as high as 16 times the ion gyrofrequency. When the streaming ions are only 1 percent of the stationary ions, the growth rate is still 4 times the gyrofrequency, but the real part is near the lower hybrid frequency. These instabilities are in addition to the Drummond-Rosenbluth ion mode. Finite β effects increase the growth rate and can be important for β greater than 10 -4 . In all this, T/sub parallel,+/ = T/sub parallel,-/ and T/sub perpendicular to/ = 0. (U.S.)

  17. Maximizing Ion Current by Space Charge Neutralization using Negative Ions and Dust Particles

    International Nuclear Information System (INIS)

    Smirnov, A.; Raitses, Y.; Fisch, N.J.

    2005-01-01

    Ion current extracted from an ion source (ion thruster) can be increased above the Child-Langmuir limit if the ion space charge is neutralized. Similarly, the limiting kinetic energy density of the plasma flow in a Hall thruster might be exceeded if additional mechanisms of space charge neutralization are introduced. Space charge neutralization with high-mass negative ions or negatively charged dust particles seems, in principle, promising for the development of a high current or high energy density source of positive light ions. Several space charge neutralization schemes that employ heavy negatively charged particles are considered. It is shown that the proposed neutralization schemes can lead, at best, only to a moderate but nonetheless possibly important increase of the ion current in the ion thruster and the thrust density in the Hall thruster

  18. Ring current shifts in {sup 19}F-NMR of membrane proteins

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dongsheng, E-mail: liudsh@shanghaitech.edu.cn; Wüthrich, Kurt, E-mail: kwuthrich@shanghaitech.edu.cn [ShanghaiTech University, iHuman Institute (China)

    2016-05-15

    Fluorine-19 NMR markers are attractive reporter groups for use in studies of complex biomacromolecular systems, in particular also for studies of function-related conformational equilibria and rate processes in membrane proteins. Advantages of {sup 19}F-NMR probes include high sensitivity of the {sup 19}F chemical shifts to variations in the non-covalent environment. Nonetheless, in studies of G protein-coupled receptors (GPCR) we encountered situations where {sup 19}F chemical shifts were not responsive to conformational changes that had been implicated by other methods. This prompted us to examine possible effects of aromatic ring current fields on the chemical shifts of {sup 19}F-NMR probes used in GPCRs. Analysis of previously reported {sup 19}F-NMR data on the β{sub 2}-adrenergic receptor and mammalian rhodopsin showed that all {sup 19}F-labeling sites which manifested conformational changes are located near aromatic residues. Although ring current effects are small when compared to other known non-covalent effects on {sup 19}F chemical shifts, there is thus an indication that their contributions are significant when studying activation processes in GPCRs, since the observed activation-related {sup 19}F-NMR chemical shifts are comparable in size to the calculated ring current shifts. Considering the impact of ring current shifts may thus be helpful in identifying promising indigenous or engineered labeling sites for future {sup 19}F-NMR studies of GPCR activation, and novel information may be obtained on the nature of conformational rearrangements near the {sup 19}F-labels. It will then also be interesting to see if the presently indicated role of ring current shifts in membrane protein studies with {sup 19}F-NMR markers can be substantiated by a more extensive data base resulting from future studies.

  19. Acceleration of polarized protons and deuterons in the ion collider ring of JLEIC

    Science.gov (United States)

    Kondratenko, A. M.; Kondratenko, M. A.; Filatov, Yu N.; Derbenev, Ya S.; Lin, F.; Morozov, V. S.; Zhang, Y.

    2017-07-01

    The figure-8-shaped ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC) is transparent to the spin. It allows one to preserve proton and deuteron polarizations using weak stabilizing solenoids when accelerating the beam up to 100 GeV/c. When the stabilizing solenoids are introduced into the collider’s lattice, the particle spins precess about a spin field, which consists of the field induced by the stabilizing solenoids and the zero-integer spin resonance strength. During acceleration of the beam, the induced spin field is maintained constant while the resonance strength experiences significant changes in the regions of “interference peaks”. The beam polarization depends on the field ramp rate of the arc magnets. Its component along the spin field is preserved if acceleration is adiabatic. We present the results of our theoretical analysis and numerical modeling of the spin dynamics during acceleration of protons and deuterons in the JLEIC ion collider ring. We demonstrate high stability of the deuteron polarization in figure-8 accelerators. We analyze a change in the beam polarization when crossing the transition energy.

  20. Ion clusters, REB, and current sheath characteristics in focused discharges

    International Nuclear Information System (INIS)

    Bortolotti, A.; Brzosko, J.; DeChiara, P.; Kilic, H.; Mezzetti, F.; Nardi, V.; Powell, C.; Zeng, D.

    1990-01-01

    Small fluctuations in the current sheath characteristics (peak current density, FWHM of leading sheath, control parameters of sheath internal structure) are linked to wide fluctuations of ion and ion cluster emission from the pinch. Magnetic probe data are used for correlating variations of current sheath parameters with particle emission intensity, Z/M composition, particle energy spectrum. The emission of ion and ion clusters at 90 degrees from the axis of a plasma focus discharge is monitored simultaneously with the 0 degrees emission. The particle energy spectrum is analyzed with a Thomson (parabola) spectrometer (time resolution ∼ 1 nanosec). The cross-sectional structure of the REB at 180 degrees along the discharge axis is monitored via the deposition of collective-field accelerated ions on a target in the REB direction. Etched tracks of ion and ion clusters are in all cases recorded on CR-39 plates. Sharp peaks of the D + -ion spectrum at 90 degrees are found for E > 200 keV/unit charge in all focused discharges. These peaks are due to ion crossing of the azimuthal magnetic field of the pinch region, in a predominant ion cluster structure

  1. An Ionosphere/Magnetosphere Coupling Current System Located in the Gap Between Saturn and its Rings

    Science.gov (United States)

    Khurana, K. K.; Dougherty, M. K.; Cao, H.; Hunt, G. J.; Provan, G.

    2017-12-01

    The Grand Finale Orbits of the Cassini spacecraft traversed through Saturn's D ring and brought the spacecraft to within 3000 km of Saturn's cloud tops. The closest approaches (CA) were near the equatorial plane of Saturn and were distributed narrowly around the local noon. The difference field (observations - internal field - magnetospheric ring current field) obtained from the Grand Finale orbits show persistent residual fields centered around the CA which diminish at higher latitudes on field lines that connect to the ring. Modeling of this perturbation in terms of internal harmonics shows that the perturbation is not of internal origin but is produced by external currents that couple the ionosphere to the magnetosphere. The sense of the current system suggests that the southern feet of the field lines in the ionosphere lead their northern footprints. We show that the observed field perturbations are consistent with a meridional Pedersen current whose strength is 1 MA/radian, i.e. comparable in strength to the Planetary-period-oscillation related current systems observed in the auroral zone. We show that the implied Lorentz force in the ionosphere extracts momentum from the faster moving southern ionosphere and passes it on to the northern ionosphere. We discuss several ideas for generating this current system. In particular, we highlight a mechanism that involves shears in the neutral winds in the thermospheric region to generate the observed magnetic field.

  2. Generation of lower hybrid and whistler waves by an ion velocity ring distribution

    International Nuclear Information System (INIS)

    Winske, D.; Daughton, W.

    2012-01-01

    Using fully kinetic simulations in two and three spatial dimensions, we consider the generation and nonlinear evolution of lower hybrid waves produced by a cold ion ring velocity distribution in a low beta plasma. We show that the initial development of the instability is very similar in two and three dimensions and not significantly modified by electromagnetic effects, consistent with linear theory. At saturation, the level of electric field fluctuations is a small fraction of the background thermal energy; the electric field and corresponding density fluctuations consist of long, field-aligned striations. Energy extracted from the ring goes primarily into heating the background ions and the electrons at comparable rates. The initial growth and saturation of the magnetic components of the lower hybrid waves are related to the electric field components, consistent with linear theory. As the growing electric field fluctuations saturate, parallel propagating whistler waves develop by the interaction of two lower hybrid waves. At later times, these whistlers are replaced by longer wavelength, parallel propagating whistlers that grow through the decay of the lower hybrid fluctuations. Wave matching conditions demonstrate these conversion processes of lower hybrid waves to whistler waves. The conversion efficiency (=ratio of the whistler wave energy to the energy in the saturated lower hybrid waves) is computed and found to be significant (∼15%) for the parameters of the three-dimensional simulation (and even larger in the two-dimensional simulation), although when normalized in terms of the initial kinetic energy in the ring ions the overall efficiency is very small ( −4 ). The results are compared with relevant linear and nonlinear theory.

  3. Development of a Bunched Beam Electron Cooler based on ERL and Circulator Ring Technology for the Jefferson Lab Electron-Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Benson, Stephen V. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Douglas, David R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hannon, Fay E. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hutton, Andrew M. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Li, Rui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Roblin, Yves R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tennant, Christopher D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, He [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2018-01-01

    Jefferson Lab is in the process of designing an electron ion collider with unprecedented luminosity at a 45 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. There are two designs for such a cooler. The first uses a conventional Energy Recovery Linac (ERL) with a magnetized beam while the second uses a circulating ring to enhance both peak and average currents experienced by the ion beam. This presentation will describe the design of both the Circulator Cooling Ring (CCR) design and that of the backup option using the stand-alone ERL operated at lower charge but higher repetition rate than the ERL injector required by the CCR-based design.

  4. Effects of decaying image currents on electron rings during compression between side walls and motion along conducting cylinders

    International Nuclear Information System (INIS)

    Herrmann, W.

    1974-11-01

    Decaying image currents consume energy which has to be supplied by the field producing electron ring. For very high currents (I > 10 3 A, particle number Ne > approximately 10 14 ) the losses become important and have to be included in the calculation of the ring dynamics. Special attention has been given to the focussing effects of the decaying image currents during compression and to the retarding force which develops when the ring is moved along a resistive cylinder. It is emphasized that in the latter case the ring experiences a 'run-away-situation', when the ratio of its velocity to the surface resistivity exceeds a certain limit. (orig.) [de

  5. Highly Efficient Spin-Current Operation in a Cu Nano-Ring

    Science.gov (United States)

    Murphy, Benedict A.; Vick, Andrew J.; Samiepour, Marjan; Hirohata, Atsufumi

    2016-11-01

    An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic.

  6. Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

    International Nuclear Information System (INIS)

    Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

    2011-01-01

    We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

  7. Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

    Energy Technology Data Exchange (ETDEWEB)

    Alexeyev, C. N.; Volyar, A. V. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Yavorsky, M. A. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Universite Bordeaux and CNRS, LOMA, UMR 5798, FR-33400 Talence (France)

    2011-12-15

    We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

  8. Some high-current ion sources for materials modification

    International Nuclear Information System (INIS)

    Taylor, T.

    1989-01-01

    Ion sources for materials modification have evolved through three distinct generations. The first generation was adopted from research accelerators. These cold-cathode plasma-discharge devices generate beam currents of less than 100 μA. The hot-cathode plasma-discharge ion sources, originally developed for isotope separation, comprise the second generation. They produce between 100 μA and 10 mA of beam current. The third generation ion sources give beam currents in excess of 10 mA. This technology, transferred from industrial accelerators, has already made SIMOX (Separation by IMplanted OXygen) into a commercially viable semiconductor process and promises to do the same for ion implantation of metals and insulators. The author focuses on the third generation technology that will play a key role in the future of ion implantation. 10 refs.; 5 figs.; 2 tabs

  9. Beam pinging, sweeping, shaking, and electron/ion collecting, at the Proton Storage Ring

    International Nuclear Information System (INIS)

    Hardek, T.W.; Macek, R.J.; Plum, M.A.; Wang, T.S.F.

    1993-01-01

    We have built, installed and tested a pinger for use as a general diagnostic at the Los Alamos Proton Storage Ring (PSR). Two 4-m-long parallel-plate electrodes with a plate spacing of 10.2 cm provide kicks of up to 1.1 mrad. A pair of solid-state pulsers may be operated in a single-pulse mode for beam pinging (tune measurements) or in a burst mode at up to 700 kHz pulse rates for beam sweeping. During our 1992 operating period we used the pinger for beam sweeping, for beam shaking, for measuring the tune shift, and we have used it as an ion chamber. Using the pinger as an ion chamber during production conditions has yielded some surprising results

  10. Description and calibration beamline SEM/Ion Chamber Current Digitizer

    International Nuclear Information System (INIS)

    Schoo, D.

    1994-05-01

    This report discusses the following on beamline SEM/ion chamber current digitizers: Module description; testing and calibration; common setup procedures; summary of fault indications and associated causes; summary of input and output connections; SEM conversion constant table; ion chamber conversion constant table; hexadecimal to decimal conversion table; and schematic diagram

  11. Heavy-ion induced current through an oxide layer

    International Nuclear Information System (INIS)

    Takahashi, Yoshihiro; Ohki, Takahiro; Nagasawa, Takaharu; Nakajima, Yasuhito; Kawanabe, Ryu; Ohnishi, Kazunori; Hirao, Toshio; Onoda, Shinobu; Mishima, Kenta; Kawano, Katsuyasu; Itoh, Hisayoshi

    2007-01-01

    In this paper, the heavy-ion induced current in MOS structure is investigated. We have measured the transient gate current in a MOS capacitor and a MOSFET induced by single heavy-ions, and found that a transient current can be observed when the semiconductor surface is under depletion condition. In the case of MOSFET, a transient gate current with both positive and negative peaks is observed if the ion hits the gate area, and that the total integrated charge is almost zero within 100-200 ns after irradiation. From these results, we conclude that the radiation-induced gate current is dominated by a displacement current. We also discuss the generation mechanism of the radiation-induced current through the oxide layer by device simulation

  12. Characterization of ion implanted silicon by the electrolytic reverse current

    International Nuclear Information System (INIS)

    Hueller, J.; Pham, M.T.

    1977-01-01

    The current voltage behaviour of ion implanted silicon electrodes in HF electrolyte is investigated. The electrolytic reverse current, i.e. the reaction rate of the minority carrier limited reactions is found to increase. The current increase depends on the implanted dose and layer stripping. Reason for the increased reverse current can be referred to radiation damage acting as generation centres for minority carriers. Measurement of the electrolytic reverse current can be used for determining damage profiles. Layer stripping is carried out by anodic dissolution in the same electrolyte. The sensitivity of this new method for characterizing ion implanted silicon layers lies at 10 11 to 10 12 atoms/cm 2 . (author)

  13. Experimental investigation of electron cooling and stacking of lead ions in a low energy accumulation ring

    CERN Document Server

    Bosser, Jacques; Chanel, M; Hill, C; Lombardi, A M; MacCaferri, R; Maury, S; Möhl, D; Molinari, G; Rossi, S; Tanke, E; Tranquille, G; Vretenar, Maurizio

    1999-01-01

    This report gives the results of a programme of experimental investigations, which were carried out to test stacking of lead ions in a storage ring (the former Low Energy Antiproton Ring, LEAR) at 4.2 MeV per nucleon. The motivation was to demonstrate the feasibility of gaining the large factor in the phase-space density required for injection into the LHC. In the first part of the report, the layout of the experiments is described, the choice of the parameters of the electron cooling system used for stacking is reported and the multi-turn injection using horizontal- and longitudinal- (and in the final project also vertical-) phase space is discussed. In the second part the experimental results are presented. Factors of vital importance are the stacking efficiency, the beam life-time and the cooling time of the ions. The beam decay owing to charge exchange with the residual gas and to recombination by the capture of cooling electrons was intensively studied. Beam instabilities and space-charge effects in the ...

  14. The storm time ring current dynamics and response to CMEs and CIRs using Van Allen Probes observations and CIMI simulations

    Science.gov (United States)

    Mouikis, Christopher; Bingham, Samuel; Kistler, Lynn; Spence, Harlan; Gkioulidou, Matina

    2017-04-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), and co-rotating interaction regions (CIR's). Using Van Allen Probes observations, we develop an empirical ring current model of the ring current pressure, the pressure anisotropy and the current density development during the storm phases for both types of storm drivers and for all MLTs inside L 6. Delineating the differences in the ring current development between these two drivers will aid our understanding of the ring current dynamics. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers. This empirical model is compared to the results of CIMI simulations of a CMEs and a CIRs where the model input is comprised of the superposed epoch solar wind conditions of the storms that comprise the empirical model. Different inner magnetosphere boundary conditions are tested in order to match the empirical model results. Comparing the model and simulation results improves our understanding of the ring current dynamics as part of the highly coupled inner magnetosphere system. In addition, within the framework of this empirical model, the prediction of the EMIC wave generation linear theory is tested using the observed plasma parameters and comparing with the observations of

  15. Solar wind parameters responsible for the plasma injection into the magnetospheric ring current region

    International Nuclear Information System (INIS)

    Bobrov, M.S.

    1977-01-01

    Solar wind effect on the magnetospheric ring-current region has been considered. The correlations with solar wind parameters of the magnitude qsub(o) proportional to the total energy of particles being injected into the magnetospheric ring-current region per one hour are studied statistically and by comparison of time variations. The data on 8 sporadic geomagnetic storms of various intensity, from moderate to very severe one, are used. It is found that qsub(o) correlates not only with the magnitude and the direction of the solar-wind magnetic field component normal to the ecliptic plane, Bsub(z), but also with the variability, sigmasub(B), of the total magnetic-field strength vector. The solar-wind flux velocity ν influences the average storm intensity but the time variations of ν during any individual storm do not correlate with those of qsub(o)

  16. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

    Science.gov (United States)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  17. Current sensorless quick charger for lithium-ion batteries

    International Nuclear Information System (INIS)

    Tsang, K.M.; Chan, W.L.

    2011-01-01

    An efficient, simple and low cost quick charger based on the double-loop controller is proposed for the charging of lithium-ion (Li-ion) batteries. With positive and negative feedback of the battery voltage, charging profile similar to the constant current and constant voltage (CC-CV) charging strategy can be performed without actually sensing the charging current. The charging time can easily be shortened by raising the level of saturation in the primary voltage control loop. Experimental results are included to demonstrate the effectiveness of the battery charger. The charger could be a low cost and high performance replacement for existing Li-ion battery chargers.

  18. Prototype high current, high duty factor negative hydrogen ion source for LAMPF

    International Nuclear Information System (INIS)

    Lawrence, G.P.; Hayward, T.D.; Jackson, J.A.

    1975-01-01

    Present plans for the high current proton storage ring at LAMPF incorporate charge changing (stripping) injection of H - ions in all modes of operation. Achievable stored current levels in this device will be strongly dependent on the maximum H - beam intensity which can be accelerated by the linac, consistent with acceptable beam spill. This requirement has stimulated a program to develop an H - ion source capable of providing a suitably high peak current (up to 25 mA) at high duty factor (up to 12 percent), with a normalized x,x' or y,y' emittance acceptable to the accelerating system. There are presently two main approaches which could lead to H - ion sources providing this kind of performance. These are (a) the charge exchange method, in which an intense proton beam is fractionally converted to H - beam in a suitable charge adding medium, and (b) the direct extraction method, in which H - ions are obtained by a surface emission process associated with a gas discharge plasma. While both approaches may eventually find optimum application in different situations, it is not obvious, at present, which scheme will turn out to be the most satisfactory for LAMPF. A prototype charge exchange H - ion source has been constructed as a first step in the development program and is presently being evaluated. Work on surface emission direct extraction techniques is in the planning stages. (U.S.)

  19. Distributions of the ion temperature, ion pressure, and electron density over the current sheet surface

    Energy Technology Data Exchange (ETDEWEB)

    Kyrie, N. P., E-mail: kyrie@fpl.gpi.ru; Markov, V. S., E-mail: natalya.kyrie@yandex.ru; Frank, A. G.; Vasilkov, D. G.; Voronova, E. V. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2016-06-15

    The distributions of the ion temperature, ion pressure, and electron density over the width (the major transverse dimension) of the current sheet have been studied for the first time. The current sheets were formed in discharges in argon and helium in 2D and 3D magnetic configurations. It is found that the temperature of argon ions in both 2D and 3D magnetic configurations is almost uniform over the sheet width and that argon ions are accelerated by the Ampère force. In contrast, the distributions of the electron density and the temperature of helium ions are found to be substantially nonuniform. As a result, in the 2D magnetic configuration, the ion pressure gradient across the sheet width makes a significant contribution (comparable with the Ampère force) to the acceleration of helium ions, whereas in the 3D magnetic configuration, the Ampère force is counterbalanced by the pressure gradient.

  20. Distributions of the ion temperature, ion pressure, and electron density over the current sheet surface

    International Nuclear Information System (INIS)

    Kyrie, N. P.; Markov, V. S.; Frank, A. G.; Vasilkov, D. G.; Voronova, E. V.

    2016-01-01

    The distributions of the ion temperature, ion pressure, and electron density over the width (the major transverse dimension) of the current sheet have been studied for the first time. The current sheets were formed in discharges in argon and helium in 2D and 3D magnetic configurations. It is found that the temperature of argon ions in both 2D and 3D magnetic configurations is almost uniform over the sheet width and that argon ions are accelerated by the Ampère force. In contrast, the distributions of the electron density and the temperature of helium ions are found to be substantially nonuniform. As a result, in the 2D magnetic configuration, the ion pressure gradient across the sheet width makes a significant contribution (comparable with the Ampère force) to the acceleration of helium ions, whereas in the 3D magnetic configuration, the Ampère force is counterbalanced by the pressure gradient.

  1. The O+ contribution and role on the ring current pressure development for CMEs and CIRs using Van Allen Probes observations

    Science.gov (United States)

    Mouikis, C.; Bingham, S.; Kistler, L. M.; Farrugia, C. J.; Spence, H. E.; Gkioulidou, M.

    2016-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), co-rotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure change the global magnetic field, which affects the transport of the radiation belts. In order to determine the field changes during a storm, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes observations to determine the ring current pressure contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. We compare storms that are related to different interplanetary drivers, CMEs and CIRs, as observed at different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers.

  2. Beam Aborts in PEP-II Rings and Lingering Drift Chamber Currents

    International Nuclear Information System (INIS)

    Meshkat, N.

    2004-01-01

    The BABAR detector at SLAC was designed to study CP-violation in B-meson decays from electron-positron collisions in the PEP-II electron-positron storage rings. Background radiation in the High Energy Ring (HER) and Low Energy Ring (LER) of PEP-II has the potential to damage the sensitive equipment in the BABAR detector. As a result, the beams in the HER and LER can be aborted to prevent such damage. In the span of a few microseconds, the HER and LER currents drop from, for example, 1450 micro Amps and 2300 micro Amps, respectively, to zero. At this time the voltage in the Drift Chamber is rapidly ramped down from a potential of 1930 V to a safe potential of 800 V, thus we would expect the currents in the Drift Chamber to quickly go to zero once the beams are aborted. However, we observe an average 15 second delay in the measured time it takes for all current in the Drift Chamber to fall below 1 micro Amp. This delay has been hypothesized as an instrumentation issue and not as a physical phenomenon. The specific sources of this error are still not completely known, but analysis suggests that it results from the interplay of the CAEN High Voltage supplies and the EPICS system and/or limitations within those systems

  3. Photon-induced tunability of the thermospin current in a Rashba ring

    Science.gov (United States)

    Abdullah, Nzar Rauf; Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2018-04-01

    The goal of this work is to show how the thermospin polarization current in a quantum ring changes in the presence of Rashba spin-orbit coupling and a quantized single photon mode of a cavity the ring is placed in. Employing the reduced density operator and a general master equation formalism, we find that both the Rashba interaction and the photon field can significantly modulate the spin polarization and the thermospin polarization current. Tuning the Rashba coupling constant, degenerate energy levels are formed corresponding to the Aharonov-Casher destructive phase interference in the quantum ring system. Our analysis indicates that the maximum spin polarization can be observed at the points of degenerate energy levels due to spin accumulation in the system without the photon field. The thermospin current is thus suppressed. In the presence of the cavity, the photon field leads to an additional kinetic momentum of the electron. As a result the spin polarization can be enhanced by the photon field.

  4. Geomagnetic storms, the Dst ring-current myth and lognormal distributions

    Science.gov (United States)

    Campbell, W.H.

    1996-01-01

    The definition of geomagnetic storms dates back to the turn of the century when researchers recognized the unique shape of the H-component field change upon averaging storms recorded at low latitude observatories. A generally accepted modeling of the storm field sources as a magnetospheric ring current was settled about 30 years ago at the start of space exploration and the discovery of the Van Allen belt of particles encircling the Earth. The Dst global 'ring-current' index of geomagnetic disturbances, formulated in that period, is still taken to be the definitive representation for geomagnetic storms. Dst indices, or data from many world observatories processed in a fashion paralleling the index, are used widely by researchers relying on the assumption of such a magnetospheric current-ring depiction. Recent in situ measurements by satellites passing through the ring-current region and computations with disturbed magnetosphere models show that the Dst storm is not solely a main-phase to decay-phase, growth to disintegration, of a massive current encircling the Earth. Although a ring current certainly exists during a storm, there are many other field contributions at the middle-and low-latitude observatories that are summed to show the 'storm' characteristic behavior in Dst at these observatories. One characteristic of the storm field form at middle and low latitudes is that Dst exhibits a lognormal distribution shape when plotted as the hourly value amplitude in each time range. Such distributions, common in nature, arise when there are many contributors to a measurement or when the measurement is a result of a connected series of statistical processes. The amplitude-time displays of Dst are thought to occur because the many time-series processes that are added to form Dst all have their own characteristic distribution in time. By transforming the Dst time display into the equivalent normal distribution, it is shown that a storm recovery can be predicted with

  5. Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    Full Text Available The relationship between the auroral electrojet indices (AE and the ring current magnetic field (DR was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'. To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE' which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence of saturation for minimum (maximum AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF Bz variations than the symmetric ring current.

  6. On Ion Cyclotron Current Drive for sawtooth control

    International Nuclear Information System (INIS)

    Eriksson, L.-G.; Johnson, T.; Hellsten, T.; Mayoral, M.-L.; McDonald, D.; Santala, M.; Vries, P. de; Coda, S.; Sauter, O.; Mueck, A.; Buttery, R.J.; Mantsinen, M.J.; Noterdaeme, J.-M.; Westerhof, E.

    2006-01-01

    Experiments using Ion Cyclotron Current Drive (ICCD) to control sawteeth are presented. In particular, discharges demonstrating shortening of fast ion induced long sawteeth reported in [L.-G. Eriksson et al., Physical Review Letters 92, 235004 (2004)] by ICCD have been analysed in detail. Numerical simulations of the ICCD driven currents are shown to be consistent with the experimental observations. They support the hypothesis that an increase of the magnetic shear, due to the driven current, at the surface where the safety factor is unity was the critical factor for the shortening of the sawteeth. In view of the potential utility of ICCD, the mechanisms for the current drive have been further investigated experimentally. This includes the influence of the averaged energy of the resonating ions carrying the current and the spectrum of the launched waves. The results of these experiments are discussed in the light of theoretical considerations. (author)

  7. Contradiction between the results of observations of resistance and critical current quantum oscillations in asymmetric superconducting rings

    International Nuclear Information System (INIS)

    Gurtovoi, V. L.; Dubonos, S. V.; Karpii, S. V.; Nikulov, A. V.; Tulin, V. A.

    2007-01-01

    Magnetic field dependences of critical current, resistance, and rectified voltage of asymmetric (half circles of different widths) and symmetrical (half circles of equal widths) aluminum rings close to the super-conducting transition were measured. All these dependences are periodic magnetic field functions with periods corresponding to the flux quantum in the ring. The periodic dependences of critical current measured in opposite directions were found to be close to each other for symmetrical rings and shifted with respect to each other by half the flux quantum in asymmetric rings with ratios between half circle widths of from 1.25 to 2. This shift of the dependences by a quarter of the flux quantum as the ring becomes asymmetric makes critical current anisotropic, which explains the effect of alternating current rectification observed for asymmetric rings. Shifts of the extrema of the periodic dependences of critical current by a quarter of the flux quantum directly contradict the results obtained by measuring asymmetric ring resistance oscillations, whose extrema are, as for symmetrical rings, observed at magnetic fluxes equal to an integer and a half of flux quanta

  8. Modular focusing ring imaging Cherenkov detector for electron-ion collider experiments

    Science.gov (United States)

    Wong, C. P.; Alfred, M.; Allison, L.; Awadi, M.; Azmoun, B.; Barbosa, F.; Barion, L.; Bennett, J.; Brooks, W.; Butler, C.; Cao, T.; Chiu, M.; Cisbani, E.; Contalbrigo, M.; Datta, A.; Del Dotto, A.; Demarteau, M.; Durham, J. M.; Dzhygadlo, R.; Elder, T.; Fields, D.; Furletova, Y.; Gleason, C.; Grosse-Perdekamp, M.; Harris, J.; Haseler, T. O. S.; He, X.; van Hecke, H.; Horn, T.; Hruschka, A.; Huang, J.; Hyde, C.; Ilieva, Y.; Kalicy, G.; Kimball, M.; Kistenev, E.; Kulinich, Y.; Liu, M.; Majka, R.; McKisson, J.; Mendez, R.; Nadel-Turonski, P.; Park, K.; Peters, K.; Rao, T.; Pisani, R.; Qiang, Y.; Rescia, S.; Rossi, P.; Sarajlic, O.; Sarsour, M.; Schwarz, C.; Schwiening, J.; da Silva, C. L.; Smirnov, N.; Stien, H. D.; Stevens, J.; Sukhanov, A.; Syed, S.; Tate, A. C.; Toh, J.; Towell, C. L.; Towell, R. S.; Tsang, T.; Turisini, M.; Wagner, R.; Wang, J.; Woody, C.; Xi, W.; Xie, J.; Zhao, Z. W.; Zihlmann, B.; Zorn, C.

    2017-11-01

    A powerful new electron-ioncollider (EIC) has been recommended in the 2015 Long Range Plan for Nuclear Science for probing the partonic structure inside nucleons and nuclei with unprecedented precision and versatility [1]. EIC detectors are currently under development [2], all of which require hadron identification over a broad kinematic range. A prototype ring imaging Cherenkov detector has been developed for hadron identification in the momentum range from 3 GeV/c to 10 GeV/c. The key feature of this new detector is a compact and modular design, achieved by using aerogel as radiator and a Fresnel lens for ring focusing. In this paper, the results from a beam test of a prototype device at Fermilab are reported.

  9. Critical current measurement in superconducting rings using an automatic inductive technique

    International Nuclear Information System (INIS)

    Gonzalez-Jorge, H.; Linares, B.; Quelle, I.; Carballo, E.; Romani, L.; Domarco, G.

    2007-01-01

    A measurement technique was developed to identify the critical current of superconducting rings. It is based on the detection of the voltage on a secondary coil when the current induced in the superconductor by a primary one go beyond to the critical value. The technique uses a DC power supply to control the AC current circulating by the primary circuit. Such circuit mainly consists on an AC power supply which gives a constant AC voltage, a primary inducting coil and a control coil with iron core. The AC current circulating by this circuit is modified with the change in the impedance of the control coil due to the fact of the DC current supplied by the power supply in parallel with it

  10. Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

    International Nuclear Information System (INIS)

    Nobusada, Katsuyuki; Yabana, Kazuhiro

    2007-01-01

    We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

  11. A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication

    International Nuclear Information System (INIS)

    Hekmati, Arsalan; Hosseini, Mehdi; Vakilian, Mehdi; Fardmanesh, Mehdi

    2012-01-01

    A method has been proposed for flat YBCO ring Fabrication. A prototype SFCL with proposed design has been fabricated using the rings. J c characteristics of the rings are measured using an innovative method. The application of flat superconductor rings has been investigated in the structure of inductive shield-type high temperature superconducting fault current limiters, HT c -SFCL. A laboratory scale inductive shield-type HT c -SFCL has been designed and fabricated using flat superconductor rings. The fabrication process has been fully presented. YBCO powder has been used for the fabrication of superconductor rings. This fabrication process, being quite innovative, is introduced completely. The method of the trapped field measurement has been used for the critical current density measurement of the fabricated superconductor rings. The device with nominal current of 2 A was tested in a 30 V circuit. The SFCL successfully limited the fault currents of up to 10 times the nominal current to an approximately fixed value of 3 A. The voltage-current characteristic of the fabricated prototype has also been obtained and has shown compatibility with the fault current limitation results.

  12. Ion beams from high-current PF facilities

    Energy Technology Data Exchange (ETDEWEB)

    Sadowski, M [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1997-12-31

    Pulsed beams of fast deuterons and impurity or admixture ions emitted from high-current PF-type facilities operated in different laboratories are dealt with. A short comparative analysis of time-integrated and time-resolved studies is presented. Particular attention is paid to the microstructure of such ion beams, and to the verification of some theoretical models. (author). 5 figs., 19 refs.

  13. Current control for magnetized plasma in direct-current plasma-immersion ion implantation

    International Nuclear Information System (INIS)

    Tang Deli; Chu, Paul K.

    2003-01-01

    A method to control the ion current in direct-current plasma-immersion ion implantation (PIII) is reported for low-pressure magnetized inductively coupled plasma. The ion current can be conveniently adjusted by applying bias voltage to the conducting grid that separates plasma formation and implantation (ion acceleration) zones without the need to alter the rf input power, gas flux, or other operating conditions. The ion current that diminishes with an increase in grid bias in magnetized plasmas can be varied from 48 to 1 mA by increasing the grid voltage from 0 to 70 V at -50 kV sample bias and 0.5 mTorr hydrogen pressure. High implantation voltage and monoenergetic immersion implantation can now be achieved by controlling the ion current without varying the macroscopic plasma parameters. The experimental results and interpretation of the effects are presented in this letter. This technique is very attractive for PIII of planar samples that require on-the-fly adjustment of the implantation current at high implantation voltage but low substrate temperature. In some applications such as hydrogen PIII-ion cut, it may obviate the need for complicated sample cooling devices that must work at high voltage

  14. Ion currents to cylindrical Langmuir probes for finite ion temperature values: Theory

    International Nuclear Information System (INIS)

    Ballesteros, J.; Palop, J.I.F.; Colomer, V.; Hernandez, M.A.

    1995-01-01

    As it is known, the experimental ion currents to a cylindrical Langmuir probe fit quite well to the radial motion theory, developed by Allen, Boyd and Reynolds (ABR Model) and generalized by Chen for the cylindrical probe case. In this paper, we are going to develop a generalization of the ABR theory, taking into account the influence of a finite ion temperature value

  15. A high current metal vapour vacuum arc ion source for ion implantation studies

    International Nuclear Information System (INIS)

    Evans, P.J.; Noorman, J.T.; Watt, G.C.; Cohen, D.D.; Bailey, G.M.

    1989-01-01

    The main features of the metal vapour vacuum arc(MEVA) as an ion source are presented. The technology utilizes the plasma production capabilities of a vacuum arc cathode. Some of the ions produced in this discharge flow through the anode and the 3 extraction grids to form an extracted ion beam. The high beam current and the potential for generating broad beams, make this technology suitable for implantation of large surface areas. The composition of the vacuum arc cathode determines the particular ions obtained from the MEVA source. 3 refs., 1 tab., 2 figs

  16. Characteristics of a high current ion source operated with lithium

    International Nuclear Information System (INIS)

    Bay, H.L.; Dullni, E.; Leismann, P.

    1986-05-01

    A low pressure arc ion source has been tested for operation with lithium. Currents up to 120 mA could be extracted through a multiple aperture extraction system at energies of 30 keV. The ion beam was neutralized up to 70% in a charge exchange cell filled with lithium vapour. The beam divergence ranged from 20 to 25 mrad full angle deduced from the spatial distribution of the collision induced Li I resonance line. Current densities from 2 to 3 mA/m 2 at a distance of 1.9 m from the source were measured either by laser induced fluorescence or with a Faraday cup. (orig.)

  17. Electric current modulation by gate frequency in a quantum ring nanotransistor

    International Nuclear Information System (INIS)

    Konopka, M.; Bokes, P.

    2013-01-01

    We presented a computational study of a dynamical gate effect applied to a tight-binding model of a ring-shaped quantum-interference nanotransistor. Compared to our former analysis, we used a model of the gate that not only controls on-site energies of the atoms but can also transfer electrons to or from the device. We have found that the electric current is modulated by the gate frequency also in this more general model. The simulations have been performed using our home-developed generalised stroboscopic wave packet approach which is very suitable for open systems and time-dependent effects. (authors)

  18. Recent advances in high current vacuum arc ion sources for heavy ion fusion

    CERN Document Server

    Qi Nian Sheng; Prasad, R R; Krishnan, M S; Anders, A; Kwan, J; Brown, I

    2001-01-01

    For a heavy ion fusion induction linac driver, a source of heavy ions with charge states 1+-3+, approx 0.5 A current beams, approx 20 mu s pulse widths and approx 10 Hz repetition rates is required. Thermionic sources have been the workhorse for the Heavy Ion Fusion (HIF) program to date, but suffer from heating problems for large areas and contamination. They are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states in short and long pulse bursts and high beam current density. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications was investigated. We have modifie...

  19. Development of high current low energy H+ ion source

    International Nuclear Information System (INIS)

    Forrester, A.T.; Crow, J.T.; Goebel, D.M.

    1978-01-01

    The ultimate goal of this work is the development of an ion source suitable for double charge exchange of D + ions to D - ions in cesium or other vapor. Since the fraction of the D + which changes to D - may be as high as 0.35 in the energy below one keV, the process appears very favorable. What is desired is a source of several hundred cm 2 area, with a D + current density greater than, say 0.2A/cm 2 . Small angular spread is essential with up to about 0.1 radian being acceptable. A simple approach to this problem appears to be through fine mesh extraction electrodes. In this system a single grid facing the ion source plasma constitutes the entire extraction electrode system. If the potential difference between the grid and the source plasma is large compared to the ion energy at the plasma boundary, then the distance s 0 is just the Child-Langmuir distance corresponding to the ion current density J and the potential difference V 0 between the plasma and the grid

  20. Detection of a weak ring current in a nonaromatic porphyrin nanoring using magnetic circular dichroism.

    Science.gov (United States)

    Kowalska, Patrycja; Peeks, Martin D; Roliński, Tomasz; Anderson, Harry L; Waluk, Jacek

    2017-12-13

    We compare the absorption and magnetic circular dichroism (MCD) spectra of a series of porphyrin oligomers - dimer, tetramer, and hexamer - bound in a linear or cyclic fashion. The MCD signal is extremely weak for low energy transitions in the linear oligomers, but it is amplified when the cyclic porphyrin hexamer binds a template, restricting rotational freedom. The appearance of Faraday A terms in the MCD spectra demonstrates the presence of a magnetic moment, and thus, uncompensated electronic current. The value of the excited state magnetic moment estimated from the A term is very low compared with those of monomeric porphyrins, which confirms the nonaromatic character of the cyclic array and the lack of a global ring current in the ground state of the neutral nanoring. DFT calculations predict the absorption and MCD patterns reasonably well, but fail to reproduce the MCD sign inversion observed in substituted monomeric zinc porphyrins ("soft" chromophores). Interestingly, a correct sign pattern is predicted by INDO/S calculations. Analysis of the MCD spectra of the monomeric porphyrin unit allowed us to distinguish between two close-lying lowest energy transitions, which some previous assignments placed further apart. The present results prove the usefulness of MCD not only for deconvolution and assignment of electronic transitions, but also as a sensitive tool for detecting electronic ring currents.

  1. HISTRAP [Heavy Ion Storage Ring for Atomic Physics] vacuum test stand for pressures of 10-12 Torr

    International Nuclear Information System (INIS)

    Johnson, J.W.; Atkins, W.H.; Dowling, D.T.; McConnell, J.W.; Milner, W.T.; Olsen, D.K.

    1988-01-01

    HISTRAP, Heavy Ion Storage Ring for Atomic Physics, is a proposed synchrotron/cooler/storage ring accelerator optimized for advanced atomic physics research. The ring has a circumference of 46.8 m, a bore diameter of about 15 cm, and requires a vacuum of 10 -12 Torr in order to decelerate highly-charged very-heavy ions down to low energies. To be able to test components and procedures to achieve this pressure, a test stand approximately modeling one-sixteenth of the ring vacuum chamber has been built. The 3.5-m-long test stand has been fabricated from 10-cm-diameter components, with 316LN stainless steel flanges. Prior to assembly, these components were vacuum fired at 950/degree/C at a pressure of 10 -4 Torr. The test stand is bakeable in situ at 300/degree/C. Pumping is achieved with two 750-L/s titanium sublimator pumps and one 60-L/s ion pump. Pressure is measured with two extractor ion gauges and a 10 -14 PP RGA. The roughing for the test stand consists of cryosorption pumps followed by a cryopump. A pressure of 4 x 10 -12 Torr has been achieved. 7 refs., 5 figs

  2. CHICSi - a 3π multi-detector system for studying heavy ion interactions inside a storage ring

    International Nuclear Information System (INIS)

    Avdeichikov, V.; Carlen, L.; Fokin, A.; Jakobsson, J.; Murin, Yu.; Maartensson, J.; Oskarsson, A.; van Veldhuizen, E.J.; Westerberg, L.; Whitlow, H.J.

    1996-01-01

    CHICSi - a 3π multi-detector system is presented. The setup consists of 576 ultra high vacuum compatible telescopes to study intermediate energy heavy ion as well as proton induced collisions at storage rings operating in slow ramping mode. Primary it will be installed at the gas-jet target station of the CELSIUS facility at The Svedberg Laboratory in Uppsala. (orig.)

  3. Longitudinal Single-Bunch Instability in the ILC Damping Rings: Estimate of Current Threshold

    International Nuclear Information System (INIS)

    Venturini, Marco; Venturini, Marco

    2008-01-01

    Characterization of single-bunch instabilities in the International Linear Collider (ILC) damping rings (DRs) has been indicated as a high-priority activity toward completion of an engineering design. In this paper we report on a first estimate of the current thresholds for the instability using numerical and analytical models of the wake potentials associated with the various machine components. The numerical models were derived (upon appropriate scaling) from designs of the corresponding components installed in existing machines. The current thresholds for instabilities were determined by numerical solution of the Vlasov equation for the longitudinal dynamics. For the DR baseline lattice as of Feb. 2007 we find the critical current for instability to be safely above the design specifications leaving room for further optimization of the choice of the momentum compaction

  4. Ion current rectification, limiting and overlimiting conductances in nanopores.

    Directory of Open Access Journals (Sweden)

    Liesbeth van Oeffelen

    Full Text Available Previous reports on Poisson-Nernst-Planck (PNP simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dependent and steady state PNP simulations under less restrictive boundary conditions, including Neumann boundary conditions applied throughout the membrane relatively far away from the nanopore. We simulated ion currents through cylindrical and conical nanopores with several surface charge configurations, studying the spatial and temporal dependence of the currents contributed by each ion species. This revealed that, due to slow co-diffusion of oppositely charged ions, steady state is generally not reached in simulations or in practice. Furthermore, it is shown that ion concentration polarization is responsible for the observed limiting conductances and ion current rectification in nanopores with asymmetric surface charges or shapes. Hence, after more than a decade of collective research attempting to understand the nature of ion current rectification in solid-state nanopores, a relatively intuitive model is retrieved. Moreover, we measured and simulated current-voltage characteristics of rectifying silicon nitride nanopores presenting overlimiting conductances. The similarity between measurement and simulation shows that overlimiting conductances can result from the increased conductance of the electric double-layer at the membrane surface at the depletion side due to voltage-induced polarization charges. The MATLAB source code of the simulation software is available via the website http://micr.vub.ac.be.

  5. HISTRAP: Proposal for a Heavy Ion Storage Ring for Atomic Physics

    Energy Technology Data Exchange (ETDEWEB)

    1988-11-01

    This paper presents an overview of the physics capabilities of HISTRAP together with a brief description of the facility and a sampling of the beams which will be available for experimentation, and surveys some of the lines of investigation in the physics of multicharged ions, molecular ion spectroscopy, condensed beams, and nuclear physics that will become possible with the advent of HISTRAP. Details of the accelerator design are discussed, including computer studies of beam tracking in the HISTRAP lattice, a discussion of the HHIRF tandem and ECR/RFQ injectors, and a description of the electron beam cooling system. In the past three years, HISTRAP has received substantial support from Oak Ridge National Laboratory management and staff. The project has used discretionary funds to develop hardware prototypes and carry out design studies. Construction has been completed on a vacuum test stand which models 1/16 of the storage ring and has attained a pressure of 4 x 10/sup -12/ Torr; a prototype rf cavity capable of accelerating beams up to 90 MeV/nucleon and decelerating to 20 keV/nucleon; and a prototype dipole magnet, one of the eight required for the HISTRAP lattice. This paper also contains a summary of the work on electron cooling carried out by one of our staff members at CERN. Building structures and services are described. Details of cost and schedule are also discussed. 77 refs.

  6. HISTRAP: Proposal for a Heavy Ion Storage Ring for Atomic Physics

    International Nuclear Information System (INIS)

    1988-11-01

    This paper presents an overview of the physics capabilities of HISTRAP together with a brief description of the facility and a sampling of the beams which will be available for experimentation, and surveys some of the lines of investigation in the physics of multicharged ions, molecular ion spectroscopy, condensed beams, and nuclear physics that will become possible with the advent of HISTRAP. Details of the accelerator design are discussed, including computer studies of beam tracking in the HISTRAP lattice, a discussion of the HHIRF tandem and ECR/RFQ injectors, and a description of the electron beam cooling system. In the past three years, HISTRAP has received substantial support from Oak Ridge National Laboratory management and staff. The project has used discretionary funds to develop hardware prototypes and carry out design studies. Construction has been completed on a vacuum test stand which models 1/16 of the storage ring and has attained a pressure of 4 x 10 -12 Torr; a prototype rf cavity capable of accelerating beams up to 90 MeV/nucleon and decelerating to 20 keV/nucleon; and a prototype dipole magnet, one of the eight required for the HISTRAP lattice. This paper also contains a summary of the work on electron cooling carried out by one of our staff members at CERN. Building structures and services are described. Details of cost and schedule are also discussed. 77 refs

  7. Broad-beam, high current, metal ion implantation facility

    International Nuclear Information System (INIS)

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the 'seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs

  8. Modelling of the ring current in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Giampieri

    2004-01-01

    Full Text Available The existence of a ring current inside Saturn's magnetosphere was first suggested by Smith et al. (1980 and Ness et al. (1981, 1982, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. Connerney et al. (1983 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set.

    First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects.

    Key words. Magnetospheric physics (current systems; planetary magnetospheres; plasma sheet

  9. Current neutralization in ballistic transport of light ion beams

    International Nuclear Information System (INIS)

    Hubbard, R.F.; Slinker, S.P.; Lampe, M.; Joyce, G.; Ottinger, P.

    1992-01-01

    Intense light ion beams are being considered as drivers to ignite fusion targets in the Laboratory Microfusion Facility (LMF). Ballistic transport of these beams from the diode to the target is possible only if the beam current is almost completely neutralized by plasma currents. This paper summarizes related work on relativistic electron beam and heavy ion beam propagation and describes a simple simulation model (DYNAPROP) which has been modified to treat light ion beam propagation. DYNAPROP uses an envelope equation to treat beam dynamics and uses rate equations to describe plasma and conductivity generation. The model has been applied both to the high current, 30 MeV Li +3 beams for LMF as well as low current, 1.2 MeV proton beams which are currently being studied on GAMBLE B at the Naval Research Laboratory. The predicted ratio of net currents to beam current is ∼0.1--0.2 for the GAMBLE experiment and ∼0.01 for LMF. The implications of these results for LMF and the GAMBLE experiments art discussed in some detail. The simple resistive model in DYNAPROP has well-known limitations in the 1 torr regime which arise primarily from the neglect of plasma electron transport. Alternative methods for treating the plasma response are discussed

  10. Non-Markovian response of ultrafast coherent electronic ring currents in chiral aromatic molecules in a condensed phase

    International Nuclear Information System (INIS)

    Mineo, H.; Lin, S. H.; Fujimura, Y.; Xu, J.; Xu, R. X.; Yan, Y. J.

    2013-01-01

    Results of a theoretical study on non-Markov response for femtosecond laser-driven coherent ring currents in chiral aromatic molecules embedded in a condensed phase are presented. Coherent ring currents are generated by coherent excitation of a pair of quasi-degenerated π-electronic excited states. The coherent electronic dynamical behaviors are strongly influenced by interactions between the electronic system and phonon bath in a condensed phase. Here, the bath correlation time is not instantaneous but should be taken to be a finite time in ultrashort time-resolved experiments. In such a case, Markov approximation breaks down. A hierarchical master equation approach for an improved semiclassical Drude dissipation model was adopted to examine the non-Markov effects on ultrafast coherent electronic ring currents of (P)-2,2 ′ -biphenol in a condensed phase. Time evolution of the coherent ring current derived in the hierarchical master equation approach was calculated and compared with those in the Drude model in the Markov approximation and in the static limit. The results show how non-Markovian behaviors in quantum beat signals of ring currents depend on the Drude bath damping constant. Effects of temperatures on ultrafast coherent electronic ring currents are also clarified

  11. The Role of Ionospheric O+ in Forming the Storm-time Ring Current

    Science.gov (United States)

    Kistler, L. M.; Mouikis, C.; Menz, A.; Bingham, S.

    2017-12-01

    During storm times, the particle pressure that creates the storm-time ring current in the inner magnetosphere can be dominated by O+. This is surprising, as the immediate source for the ring current is the nightside plasma sheet, and O+ is usually not the dominant species in the plasma sheet. In this talk we examine the many factors that lead to this result. The O+ outflow is enhanced during geomagnetically active times. The transport paths of O+ and H+ are different, such that the O+ that reaches the near-earth plasma sheet is more energetic than H+. The source spectrum in the near-earth plasma sheet can be harder for O+ than for H+, perhaps due to substorm injections, so that the more energetic plasma has a higher O+/H+ ratio. And finally the plasma sheet O+ can be more abundant towards the beginning of the storm, when the convection is largest, so the enhanced O+ is brought the deepest into the inner magnetosphere. We will discuss the interrelationships between these different effects as well as the ways in which O+ itself may influence the system.

  12. Energization of the Ring Current through Convection of Substorm Enhancements of the Plasma Sheet Source.

    Science.gov (United States)

    Menz, A.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Henderson, M. G.; Matsui, H.

    2017-12-01

    It has been shown that electric field strength and night-side plasma sheet density are the two best predictors of the adiabatic energy gain of the ring current during geomagnetic storms (Liemohn and Khazanov, 2005). While H+ dominates the ring current during quiet times, O+ can contribute substantially during geomagnetic storms. Substorm activity provides a mechanism to enhance the energy density of O+ in the plasma sheet during geomagnetic storms, which is then convected adiabatically into the inner-magnetosphere. Using the Van Allen Probes data in the the plasma sheet source region (defined as L>5.5 during storms) and the inner magnetosphere, along with LANL-GEO data to identify substorm injection times, we show that adiabatic convection of O+ enhancements in the source region can explain the observed enhancements in the inner magnetosphere. We use the UNH-IMEF electric field model to calculate drift times from the source region to the inner magnetosphere to test whether enhancements in the inner-magnetosphere can be explained by dipolarization driven enhancements in the plasma sheet source hours before.

  13. THE POTENTIAL FOR NEUTRINO PHYSICS AT MUON COLLIDERS AND DEDICATED HIGH CURRENT MUON STORAGE RINGS

    International Nuclear Information System (INIS)

    BIGI, I.; BOLTON, T.; FORMAGGIO, J.; HARRIS, D.; MORFIN, J.; SPENTZOURIS, P.; YU, J.; KAYSER, B.; KING, B.J.; MCFARLAND, K.; PETROV, A.; SCHELLMAN, H.; VELASCO, M.; SHROCK, R.

    2000-01-01

    Conceptual design studies are underway for both muon colliders and high-current non-colliding muon storage rings that have the potential to become the first true neutrino factories. Muon decays in long straight sections of the storage rings would produce uniquely intense and precisely characterized two-component neutrino beams--muon neutrinos plus electron antineutrinos from negative muon decays and electron neutrinos plus muon antineutrinos from positive muons. This article presents a long-term overview of the prospects for these facilities to greatly extend the capabilities for accelerator-based neutrino physics studies for both high rate and long baseline neutrino experiments. As the first major physics topic, recent experimental results involving neutrino oscillations have motivated a vigorous design effort towards dedicated neutrino factories that would store muon beams of energies 50 GeV or below. These facilities hold the promise of neutrino oscillation experiments with baselines up to intercontinental distances and utilizing well understood beams that contain, for the first time, a substantial component of multi-GeV electron-flavored neutrinos. In deference to the active and fast-moving nature of neutrino oscillation studies, the discussion of long baseline physics at neutrino factories has been limited to a concise general overview of the relevant theory, detector technologies, beam properties, experimental goals and potential physics capabilities. The remainder of the article is devoted to the complementary high rate neutrino experiments that would study neutrino-nucleon and neutrino-electron scattering and would be performed at high performance detectors placed as close as is practical to the neutrino production straight section of muon storage rings in order to exploit beams with transverse dimensions as small as a few tens of centimeters

  14. THE POTENTIAL FOR NEUTRINO PHYSICS AT MUON COLLIDERS AND DEDICATED HIGH CURRENT MUON STORAGE RINGS

    Energy Technology Data Exchange (ETDEWEB)

    BIGI,I.; BOLTON,T.; FORMAGGIO,J.; HARRIS,D.; MORFIN,J.; SPENTZOURIS,P.; YU,J.; KAYSER,B.; KING,B.J.; MCFARLAND,K.; PETROV,A.; SCHELLMAN,H.; VELASCO,M.; SHROCK,R.

    2000-05-11

    Conceptual design studies are underway for both muon colliders and high-current non-colliding muon storage rings that have the potential to become the first true neutrino factories. Muon decays in long straight sections of the storage rings would produce uniquely intense and precisely characterized two-component neutrino beams--muon neutrinos plus electron antineutrinos from negative muon decays and electron neutrinos plus muon antineutrinos from positive muons. This article presents a long-term overview of the prospects for these facilities to greatly extend the capabilities for accelerator-based neutrino physics studies for both high rate and long baseline neutrino experiments. As the first major physics topic, recent experimental results involving neutrino oscillations have motivated a vigorous design effort towards dedicated neutrino factories that would store muon beams of energies 50 GeV or below. These facilities hold the promise of neutrino oscillation experiments with baselines up to intercontinental distances and utilizing well understood beams that contain, for the first time, a substantial component of multi-GeV electron-flavored neutrinos. In deference to the active and fast-moving nature of neutrino oscillation studies, the discussion of long baseline physics at neutrino factories has been limited to a concise general overview of the relevant theory, detector technologies, beam properties, experimental goals and potential physics capabilities. The remainder of the article is devoted to the complementary high rate neutrino experiments that would study neutrino-nucleon and neutrino-electron scattering and would be performed at high performance detectors placed as close as is practical to the neutrino production straight section of muon storage rings in order to exploit beams with transverse dimensions as small as a few tens of centimeters.

  15. High current pulsed linear ion accelerators for inertial fusion applications

    International Nuclear Information System (INIS)

    Humphries, S. Jr.; Yonas, G.; Poukey, J.W.

    1978-01-01

    Pulsed ion beams have a number of advantages for use as inertial fusion drivers. Among these are classical interaction with targets and good efficiency of production. As has been pointed out by members of the accelerator community, multistage accelerators are attractive in this context because of lower current requirements, low power flow per energy conversion stage and low beam divergence at higher ion energies. On the other hand, current transport limits in conventional accelerators constrain them to the use of heavy ions at energies much higher than those needed to meet the divergence requirements, resulting in large, costly systems. We have studied methods of neutralizing ion beams with electrons within the accelerator volume to achieve higher currents. The aim is to arrive at an inexpensive accelerator that can advantageously use existing pulsed voltage technology while being conservative enough to achieve a high repetition rate. Typical output parameters for reactor applications would be an 0 + beam of 30 kA at 300 MeV. We will describe reactor scaling studies and the physics of neutralized linear accelerators using magnetic fields to control the electron dynamics. Recent results are discussed from PULSELAC, a five stage multikiloampere device being tested at Sandia Laboratories

  16. Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility.

    Science.gov (United States)

    Adonin, A A; Hollinger, R

    2014-02-01

    In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

  17. Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

    Directory of Open Access Journals (Sweden)

    K.-H. Glassmeier

    Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way, 
    m
    = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed

  18. Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

    Directory of Open Access Journals (Sweden)

    K.-H. Glassmeier

    1999-03-01

    Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way,  m = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed.Key words. Magnetospheric physics (energetic particles , trapped

  19. The storm-time ring current: a statistical analysis at two widely separated low-latitude stations

    Directory of Open Access Journals (Sweden)

    P. Francia

    2004-11-01

    Full Text Available We conducted a statistical analysis of the geomagnetic field variations during the storm main phase at two low-latitude stations, separated by several hours in magnetic local time, in order to investigate the asymmetry and longitudinal extent of the storm-time ring current. The results show evidence for an asymmetric current which typically extends from evening to noon and, during moderate solar wind electric field conditions, up to the early morning, confirming the important role of the magnetospheric convection in the ring current energization. We also analyzed a possible relationship between the local current intensity during the storm main phase and the substorm activity observed at different time delays τ with respect to the storm onset. The results show a significant anticorrelation for τ =-1h, indicating that if the substorm activity is high just before the storm, a weaker ring current develops.

  20. Experimental study of collective effects in BEP storage ring with high stored current

    International Nuclear Information System (INIS)

    Danilov, V.; Koop, I.; Lysenko, A.; Militsyn, B.; Nesterenko, I.; Perevedentsev, E.; Pozdeev, E.; Ptitsin, V.; Shatunov, Yu.; Vasserman, I.

    1993-01-01

    The results of extensive investigation of beam dynamics with high current in BEP booster are presented. Strong bunch lengthening due to the potential well distortion by the inductive impedance was observed on the background of the multiple intrabeam scattering and of the ion accumulation (in the e - beam). The octupole and sextupole corrections enabled control of collective damping of the head-tail modes. Fast damping is also observed at zero chromaticity, this is attributed to the injection kickers acting as transmission lines. The proper tuning of the nonlinearity corrections cures the transverse instabilities and enables capability to store up to 0.8A current in a single bunch

  1. Storage Rings

    International Nuclear Information System (INIS)

    Fischer, W.

    2010-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

  2. An auroral westward flow channel (AWFC and its relationship to field-aligned current, ring current, and plasmapause location determined using multiple spacecraft observations

    Directory of Open Access Journals (Sweden)

    M. L. Parkinson

    2007-02-01

    Full Text Available An auroral westward flow channel (AWFC is a latitudinally narrow channel of unstable F-region plasma with intense westward drift in the dusk-to-midnight sector ionosphere. AWFCs tend to overlap the equatorward edge of the auroral oval, and their life cycle is often synchronised to that of substorms: they commence close to substorm expansion phase onset, intensify during the expansion phase, and then decay during the recovery phase. Here we define for the first time the relationship between an AWFC, large-scale field-aligned current (FAC, the ring current, and plasmapause location. The Tasman International Geospace Environment Radar (TIGER, a Southern Hemisphere HF SuperDARN radar, observed a jet-like AWFC during ~08:35 to 13:28 UT on 7 April 2001. The initiation of the AWFC was preceded by a band of equatorward expanding ionospheric scatter (BEES which conveyed an intense poleward electric field through the inner plasma sheet. Unlike previous AWFCs, this event was not associated with a distinct substorm surge; rather it occurred during an interval of persistent, moderate magnetic activity characterised by AL~−200 nT. The four Cluster spacecraft had perigees within the dusk sector plasmasphere, and their trajectories were magnetically conjugate to the radar observations. The Waves of High frequency and Sounder for Probing Electron density by Relaxation (WHISPER instruments on board Cluster were used to identify the plasmapause location. The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE EUV experiment also provided global-scale observations of the plasmapause. The Cluster fluxgate magnetometers (FGM provided successive measurements specifying the relative location of the ring current and filamentary plasma sheet current. An analysis of Iridium spacecraft magnetometer measurements provided estimates of large-scale ionospheric FAC in relation to the AWFC evolution. Peak flows in the AWFC were located close to the peak of a Region 2

  3. High ion charge states in a high-current, short-pulse, vacuum ARC ion sources

    International Nuclear Information System (INIS)

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

    1996-01-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1-4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several μs) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution

  4. High ion charge states in a high-current, short-pulse, vacuum arc ion source

    International Nuclear Information System (INIS)

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

    1995-09-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1--4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several micros) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution

  5. Tests of a niobium split-ring superconducting heavy ion accelerating structure

    International Nuclear Information System (INIS)

    Benaroya, R.; Bollinger, L.M.; Jaffey, A.H.; Khoe, T.K.; Olesen, M.C.; Scheibelhut, C.H.; Shepard, K.W.; Wesolowski, W.A.

    1976-01-01

    A niobium split-ring accelerating structure designed for use in the Argonne superconducting heavy-ion energy booster was successfully tested. The superconducting resonator has a resonant frequency of 97 MHz and an optimum particle velocity β = 0.11. Ultimate performance is expected to be limited by peak surface fields, which in this structure are 4.7 E/sub a/ electric and 170 E/sub a/ (Gauss) magnetic, where E/sub a/ is the effective accelerating gradient in MV/m. The rf losses in two demountable superconducting joints severely limited performance in initial tests. Following independent measurements of the rf loss properties of several types of demountable joints, one demountable joint was eliminated and the other modified. Subsequently, the resonator could be operated continuously at E/sub a/ = 3.6 MV/m (corresponding to an energy gain of 1.3 MeV per charge) with 10W rf input power. Maximum field level was limited by electron loading. The mechanical stability of the resonator under operating conditions is excellent: vibration induced eigenfrequency noise is less than 120 Hz peak to peak, and the radiation pressure induced frequency shift is Δf/f = 1.6 x 10 -6 E/sub a/ 2

  6. The search for electric dipole moments of light ions in storage rings

    International Nuclear Information System (INIS)

    Rathmann, Frank; Saleev, Artem; Nikolaev, N N

    2013-01-01

    The Standard Model (SM) of Particle Physics is not capable of accounting for the apparent matter-antimatter asymmetry of our universe. Physics beyond the SM is required and is searched for by (i) employing highest energies (e.g., at LHC), and (ii) striving for ultimate precision and sensitivity (e.g., in the search for electric dipole moments (EDMs)). Permanent EDMs of particles violate both time reversal (T) and parity (P) invariance, and are via the CPT-theorem also CP-violating. Finding an EDM would be a strong indication for physics beyond the SM, and reducing upper limits further provides crucial tests for any corresponding theoretical model, e.g., SUSY. Direct searches for proton and deuteron EDMs bear the potential to reach sensitivities beyond 10 −29 e·cm. For an all-electric proton storage ring, this goal is pursued by the US-based srEDM collaboration [1], while the newly founded Jülich-based JEDI collaboration [2] is pursuing an approach using a combined electric-magnetic lattice, which shall provide access to the EDMs of protons, deuterons, and 3 He ions in the same machine. In addition, JEDI has recently proposed making a direct measurement of the proton and/or deuteron EDM at COSY using resonant techniques involving Wien filters

  7. Tests of a niobium split-ring superconducting heavy ion accelerating structure

    Energy Technology Data Exchange (ETDEWEB)

    Benaroya, R.; Bollinger, L.M.; Jaffey, A.H.; Khoe, T.K.; Olesen, M.C.; Scheibelhut, C.H.; Shepard, K.W.; Wesolowski, W.A.

    1976-01-01

    A niobium split-ring accelerating structure designed for use in the Argonne superconducting heavy-ion energy booster was successfully tested. The superconducting resonator has a resonant frequency of 97 MHz and an optimum particle velocity ..beta.. = 0.11. Ultimate performance is expected to be limited by peak surface fields, which in this structure are 4.7 E/sub a/ electric and 170 E/sub a/ (Gauss) magnetic, where E/sub a/ is the effective accelerating gradient in MV/m. The rf losses in two demountable superconducting joints severely limited performance in initial tests. Following independent measurements of the rf loss properties of several types of demountable joints, one demountable joint was eliminated and the other modified. Subsequently, the resonator could be operated continuously at E/sub a/ = 3.6 MV/m (corresponding to an energy gain of 1.3 MeV per charge) with 10W rf input power. Maximum field level was limited by electron loading. The mechanical stability of the resonator under operating conditions is excellent: vibration induced eigenfrequency noise is less than 120 Hz peak to peak, and the radiation pressure induced frequency shift is ..delta..f/f = 1.6 x 10/sup -6/ E/sub a//sup 2/.

  8. Heavy-Ion Injector for the High Current Experiment

    Science.gov (United States)

    Bieniosek, F. M.; Henestroza, E.; Kwan, J. W.; Prost, L.; Seidl, P.

    2001-10-01

    We report on progress in development of the Heavy-Ion Injector at LBNL, which is being prepared for use as an injector for the High Current Experiment (HCX). It is composed of a 10-cm-diameter surface ionization source, an extraction diode, and an electrostatic quadrupole (ESQ) accelerator, with a typical operating current of 0.6 A of potassium ions at 1.8 MeV, and a beam pulse length of 4.5 microsecs. We have improved the Injector equipment and diagnostics, and have characterized the source emission and radial beam profiles at the diode and ESQ regions. We find improved agreement with EGUN predictions, and improved compatibility with the downstream matching section. Plans are to attach the matching section and the initial ESQ transport section of HCX. Results will be presented and compared with EGUN and WARP simulations.

  9. High-precision X-ray spectroscopy of highly-charged ions at the experimental storage ring using silicon microcalorimeters

    Science.gov (United States)

    Scholz, Pascal A.; Andrianov, Victor; Echler, Artur; Egelhof, Peter; Kilbourne, Caroline; Kiselev, Oleg; Kraft-Bermuth, Saskia; McCammon, Dan

    2017-10-01

    X-ray spectroscopy on highly charged heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. One limitation of the current accuracy of such experiments is the energy resolution of available X-ray detectors for energies up to 100 keV. To improve this accuracy, a novel detector concept, namely the concept of microcalorimeters, is exploited for this kind of measurements. The microcalorimeters used in the present experiments consist of silicon thermometers, ensuring a high dynamic range, and of absorbers made of high-Z material to provide high X-ray absorption efficiency. Recently, besides an earlier used detector, a new compact detector design, housed in a new dry cryostat equipped with a pulse tube cooler, was applied at a test beamtime at the experimental storage ring (ESR) of the GSI facility in Darmstadt. A U89+ beam at 75 MeV/u and a 124Xe54+ beam at various beam energies, both interacting with an internal gas-jet target, were used in different cycles. This test was an important benchmark for designing a larger array with an improved lateral sensitivity and statistical accuracy.

  10. RF current generation near the ion cyclotron frequency

    International Nuclear Information System (INIS)

    Watkins, J.G.

    1982-01-01

    An experiment has been conducted to measure unipolar currents driven by directional radio frequency waves in a cylindrical plasma mirror machine near the ion cyclotron frequency. The directional waves were launched using a four phase helical coupler which allowed the selection of both azimuthal mode number (m = +1) and direction of wave propagation. Plasma diagnostics include electron density measurements (4 mm microwave interferometer), electron temperature measurements (floating double probe), wave amplitude and coupling measurements (magnetic probes). RF power measurements (RF voltage and current probes) and RF driven plasma current measurements (Rogowski loops and current transformers). End electrodes provided a necessary external return path and an alternate method for measuring the current. Theoretical work includes an analytic approximation to the nonlinear problem of a particle in a traveling wave and computer simulations that extend this result. Nonlinear particle drifts other than trapping were found both with and without the presence of particle collisions

  11. Studies in High Current Density Ion Sources for Heavy Ion Fusion Applications

    International Nuclear Information System (INIS)

    Chacon-Golcher, E.

    2002-01-01

    This dissertation develops diverse research on small (diameter ∼ few mm), high current density (J ∼ several tens of mA/cm 2 ) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield ( ) at different operating conditions are presented for K + and Cs + contact ionization sources and potassium aluminum silicate sources. Maximum values for a K + beam of ∼90 mA/cm 2 were observed in 2.3 (micro)s pulses. Measurements of beam intensity profiles and emittances are included. Measurements of neutral particle desorption are presented at different operating conditions which lead to a better understanding of the underlying atomic diffusion processes that determine the lifetime of the emitter. Estimates of diffusion times consistent with measurements are presented, as well as estimates of maximum repetition rates achievable. Diverse studies performed on the composition and preparation of alkali aluminosilicate ion sources are also presented. In addition, this work includes preliminary work carried out exploring the viability of an argon plasma ion source and a bismuth metal vapor vacuum arc (MEVVA) ion source. For the former ion source, fast rise-times (∼ 1 (micro)s), high current densities (∼ 100 mA/cm 2 ) and low operating pressures ( e psilon) n (le) 0.006 π mm · mrad) although measured currents differed from the desired ones (I ∼ 5mA) by about a factor of 10

  12. Studies in High Current Density Ion Sources for Heavy Ion Fusion Applications

    Energy Technology Data Exchange (ETDEWEB)

    Chacon-Golcher, Edwin [Univ. of California, Berkeley, CA (United States)

    2002-06-01

    This dissertation develops diverse research on small (diameter ~ few mm), high current density (J ~ several tens of mA/cm2) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield () at different operating conditions are presented for K+ and Cs+ contact ionization sources and potassium aluminum silicate sources. Maximum values for a K+ beam of ~90 mA/cm2 were observed in 2.3 μs pulses. Measurements of beam intensity profiles and emittances are included. Measurements of neutral particle desorption are presented at different operating conditions which lead to a better understanding of the underlying atomic diffusion processes that determine the lifetime of the emitter. Estimates of diffusion times consistent with measurements are presented, as well as estimates of maximum repetition rates achievable. Diverse studies performed on the composition and preparation of alkali aluminosilicate ion sources are also presented. In addition, this work includes preliminary work carried out exploring the viability of an argon plasma ion source and a bismuth metal vapor vacuum arc (MEVVA) ion source. For the former ion source, fast rise-times (~ 1 μs), high current densities (~ 100 mA/cm+) and low operating pressures (< 2 mtorr) were verified. For the latter, high but acceptable levels of beam emittance were measured (εn ≤ 0.006 π· mm · mrad) although measured currents differed from the desired ones (I ~ 5mA) by about a factor of 10.

  13. Toward a New Test of the Relativistic Time Dilation Factor by Laser Spectroscopy of Fast Ions in a Storage Ring

    International Nuclear Information System (INIS)

    Saathoff, G.; Eisenbarth, U.; Hannemann, S.; Hoog, I.; Huber, G.; Karpuk, S.; Krohn, S.; Lassen, J.; Schwalm, D.; Weidemueller, M.; Wolf, A.; Gwinner, G.

    2003-01-01

    The frequency measurement of Doppler-shifted optical lines of ions circulating in a storage ring at high speed permits a sensitive test of the relativistic Doppler-formula and, hence, the time dilation factor γ SR of special relativity. Previous measurements at the storage ring TSR with 7 Li + at v=0.065c gave a new, improved limit, but were hampered by the large observed linewidth, exceeding the natural width 15-fold. Recently we have identified the broadening to be caused by velocity-changing processes in the storage ring. Saturation spectroscopy has proven to be largely immune against these effects and has yielded linewidths only a few MHz larger than the natural one. This is the major ingredient for an improved test of γ SR , which is now under way.

  14. Toward a New Test of the Relativistic Time Dilation Factor by Laser Spectroscopy of Fast Ions in a Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Saathoff, G.; Eisenbarth, U.; Hannemann, S. [Max-Planck-Institut fuer Kernphysik (Germany); Hoog, I.; Huber, G.; Karpuk, S. [Universitaet Mainz, Institut fuer Physik (Germany); Krohn, S. [Max-Planck-Institut fuer Kernphysik (Germany); Lassen, J. [Universitaet Mainz, Institut fuer Physik (Germany); Schwalm, D.; Weidemueller, M.; Wolf, A.; Gwinner, G. [Max-Planck-Institut fuer Kernphysik (Germany)

    2003-03-15

    The frequency measurement of Doppler-shifted optical lines of ions circulating in a storage ring at high speed permits a sensitive test of the relativistic Doppler-formula and, hence, the time dilation factor {gamma}{sub SR} of special relativity. Previous measurements at the storage ring TSR with {sup 7}Li{sup +} at v=0.065c gave a new, improved limit, but were hampered by the large observed linewidth, exceeding the natural width 15-fold. Recently we have identified the broadening to be caused by velocity-changing processes in the storage ring. Saturation spectroscopy has proven to be largely immune against these effects and has yielded linewidths only a few MHz larger than the natural one. This is the major ingredient for an improved test of {gamma}{sub SR}, which is now under way.

  15. Heavy-Ion Reactions: a current awareness bulletin

    International Nuclear Information System (INIS)

    Kinser, W.H.

    1985-01-01

    This current awareness bulletin announces on a semimonthly basis the current worldwide information entered into the Energy Data Base on theoretical and experimental studies (including instrumentation) of heavy-ion (A > 4) nuclear reactions for nuclear structure studies; for producing new isotopes and superheavy elements for nuclear, atomic, and chemical properties studies; for understanding quantum chromodynamics as an exact theory of the strong nuclear force; and for studying the equations of state and phases of nuclear matter (pion condensate and quark matter) of special interest in astrophysics, and cosmology. An abstract is included with each citation. Regular publication began in January 1985

  16. Water flow in carbon-based nanoporous membranes impacted by interactions between hydrated ions and aromatic rings.

    Science.gov (United States)

    Liu, Jian; Shi, Guosheng; Fang, Haiping

    2017-02-24

    Carbon-based nanoporous membranes, such as carbon nanotubes (CNTs), graphene/graphene oxide and graphyne, have shown great potential in water desalination and purification, gas and ion separation, biosensors, and lithium-based batteries, etc. A deep understanding of the interaction between hydrated ions in an aqueous solution and the graphitic surface in systems composed of water, ions and a graphitic surface is essential for applications with carbon-based nanoporous membrane platforms. In this review, we describe the recent progress of the interaction between hydrated ions and aromatic ring structures on the carbon-based surface and its applications in the water flow in a carbon nanotube. We expect that these works can be extended to the understanding of water flow in other nanoporous membranes, such as nanoporous graphene, graphyne and stacked sheets of graphene oxide.

  17. Stereo ENA Imaging of the Ring Current and Multi-point Measurements of Suprathermal Particles and Magnetic Fields by TRIO-CINEMA

    Science.gov (United States)

    Lin, R. P.; Sample, J. G.; Immel, T. J.; Lee, D.; Horbury, T. S.; Jin, H.; SEON, J.; Wang, L.; Roelof, E. C.; Lee, E.; Parks, G. K.; Vo, H.

    2012-12-01

    The TRIO (Triplet Ionospheric Observatory) - CINEMA (Cubesat for Ions, Neutrals, Electrons, & Magnetic fields) mission consists of three identical 3-u cubesats to provide high sensitivity, high cadence, stereo measurements of Energetic Neutral Atoms (ENAs) from the Earth's ring current with ~1 keV FWHM energy resolution from ~4 to ~200 keV, as well as multi-point in situ measurements of magnetic fields and suprathermal electrons (~2 -200 keV) and ions (~ 4 -200 keV) in the auroral and ring current precipitation regions in low Earth orbit (LEO). A new Suprathermal Electron, Ion, Neutral (STEIN) instrument, using a 32-pixel silicon semiconductor detector with an electrostatic deflection system to separate ENAs from ions and from electrons below 30 keV, will sweep over most of the sky every 15 s as the spacecraft spins at 4 rpm. In addition, inboard and outboard (on an extendable 1m boom) miniature magnetoresistive sensor magnetometers will provide high cadence 3-axis magnetic field measurements. An S-band transmitter will be used to provide ~8 kbps orbit-average data downlink to the ~11m diameter antenna of the Berkeley Ground Station.The first CINEMA (funded by NSF) is scheduled for launch on August 14, 2012 into a 65 deg. inclination LEO. Two more identical CINEMAs are being developed by Kyung Hee University (KHU) in Korea under the World Class University (WCU) program, for launch in November 2012 into a Sun-synchronous LEO to form TRIO-CINEMA. A fourth CINEMA is being developed for a 2013 launch into LEO. This LEO constellation of nanosatellites will provide unique measurements highly complementary to NASA's RBSP and THEMIS missions. Furthermore, CINEMA's development of miniature particle and magnetic field sensors, and cubesat-size spinning spacecraft may be important for future constellation space missions. Initial results from the first CINEMA will be presented if available.

  18. Dst and a map of average equivalent ring current: 1958-2007

    Science.gov (United States)

    Love, J. J.

    2008-12-01

    A new Dst index construction is made using the original hourly magnetic-observatory data collected over the years 1958-2007; stations: Hermanus South Africa, Kakioka Japan, Honolulu Hawaii, and San Juan Puerto Rico. The construction method we use is generally consistent with the algorithm defined by Sugiura (1964), and which forms the basis for the standard Kyoto Dst index. This involves corrections for observatory baseline shifts, subtraction of the main-field secular variation, and subtraction of specific harmonics that approximate the solar-quiet (Sq) variation. Fourier analysis of the observatory data reveals the nature of Sq: it consists primarily of periodic variation driven by the Earth's rotation, the Moon's orbit, the Earth's orbit, and, to some extent, the solar cycle. Cross coupling of the harmonics associated with each of the external periodic driving forces results in a seemingly complicated Sq time series that is sometimes considered to be relatively random and unpredictable, but which is, in fact, well described in terms of Fourier series. Working in the frequency domain, Sq can be filtered out, and, upon return to the time domain, the local disturbance time series (Dist) for each observatory can be recovered. After averaging the local disturbance time series from each observatory, the global magnetic disturbance time series Dst is obtained. Analysis of this new Dst index is compared with that produced by Kyoto, and various biases and differences are discussed. The combination of the Dist and Dst time series can be used to explore the local-time/universal-time symmetry of an equivalent ring current. Individual magnetic storms can have a complicated disturbance field that is asymmetrical in longitude, presumably due to partial ring currents. Using 50 years of data we map the average local-time magnetic disturbance, finding that it is very nearly proportional to Dst. To our surprise, the primary asymmetry in mean magnetic disturbance is not between

  19. Controlling chaos in the current-driven ion acoustic instability

    International Nuclear Information System (INIS)

    Fukuyama, T.; Taniguchi, K.; Kawai, Y.

    2002-01-01

    Control of intermittent chaos caused by the current-driven ion acoustic instability is attempted and the controlling mechanism is investigated. When a small negative dc voltage is applied to the chaotic system as a perturbation, the system changes from a chaotic state to a periodic state while maintaining the instability, indicating that the chaotic state caused by the ion acoustic instability is well controlled by applying a small negative dc voltage. A hysteresis structure is observed on the V-I curve of the mesh grid to which the negative dc voltage to control is applied. Furthermore, when a negative dc voltage is applied to the state which shows a laminar structure existing under same experimental conditions, the system becomes chaotic via a bifurcation. Driven-chaos is excited when a negative dc voltage is applied to the laminar state. Applying a small negative dc voltage leads to controlling intermittent chaos while exciting driven-chaos

  20. Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials.

    Science.gov (United States)

    Liu, Chao; Schauff, Joseph; Lee, Seokhyeong; Cho, Jeong-Hyun

    2017-03-23

    Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the

  1. Action potential propagation: ion current or intramembrane electric field?

    Science.gov (United States)

    Martí, Albert; Pérez, Juan J; Madrenas, Jordi

    2018-01-01

    The established action potential propagation mechanisms do not satisfactorily explain propagation on myelinated axons given the current knowledge of biological channels and membranes. The flow across ion channels presents two possible effects: the electric potential variations across the lipid bilayers (action potential) and the propagation of an electric field through the membrane inner part. The proposed mechanism is based on intra-membrane electric field propagation, this propagation can explain the action potential saltatory propagation and its constant delay independent of distance between Ranvier nodes in myelinated axons.

  2. Architecture and control of a high current ion implanter system

    International Nuclear Information System (INIS)

    Bayer, E.H.; Paul, L.F.; Kranik, J.R.

    1979-01-01

    The design of an ion implant system for use in production requires that special attention be given to areas of design which normally are not emphasized on research or development type ion implanters. Manually operated, local controls are replaced by remote controls, automatic sequencing, and digital displays. For ease of maintenance and replication the individual components are designed as simply as possible and are contained in modules of separate identities, joined only by the beam line and electrical interconnections. A production environment also imposes requirements for the control of contamination and maintainability of clean room integrity. For that reason the major portion of the hardware is separated from the clean operator area and is housed in a maintenance core area. The controls of a production system should also be such that relatively unskilled technicians are able to operate the system with optimum repeatability and minimum operator intervention. An extensive interlock system is required. Most important, for use in production the ion implant system has to have a relatively high rate of throughput. Since the rate of throughput at a given dose is a function of beam current, pumpdown time and wafer handling capacity, design of components affecting these parameters has been optimized. Details of the system are given. (U.K.)

  3. A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

    Science.gov (United States)

    Kirk, Ansgar Thomas; Kobelt, Tim; Spehlbrink, Hauke; Zimmermann, Stefan

    2018-05-01

    Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region. [Figure not available: see fulltext.

  4. High-current negative-ion sources for pulsed spallation neutron sources: LBNL workshop, October 1994

    International Nuclear Information System (INIS)

    Alonso, J.R.

    1995-09-01

    The neutron scattering community has endorsed the need for a high-power (1 to 5 MW) accelerator-driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (sub-microsecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 kW source in the UK), and call for a high-current (approx. 100 mA peak) H- source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The I to 5 GeV proton beam is extracted in a single turn and brought to the target-moderator stations. The high current, high duty-factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. The Workshop reported on here, held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H- source technologies, and identified necessary R ampersand D efforts to bridge the gap

  5. Formation mechanism for the structure of the magnetic-storm ring current

    CERN Document Server

    Tverskoy, B A

    1999-01-01

    An analysis is presented for the implications of the relationship between the amplitude of the Dst variation and the position L sub m sub a sub x of the intensity maximum of the relativistic-electron belt that arises immediately after the cessation of a storm. The quantity L sub m sub a sub x is regarded to correspond to the position of the pressure maximum of the ring-current plasma at the moment of the maximum amplitude of the storm main phase. Under this assumption, the structure of the mentioned plasma formation is calculated, and the idea is substantiated that the plasma cloud is adiabatically driven deep into the magnetosphere during the sub-storm and subsequently symmetrized (this idea was originally put forward by the author on the basis of the theory of the magnetosphere-ionosphere interaction). It is shown that the presence of the mentioned relationship implies the existence of a certain boundary where the entropy calculated for a unit-magnetic-flux tube always has the same value. The applicability ...

  6. Formation mechanism for the structure of the magnetic-storm ring current

    International Nuclear Information System (INIS)

    Tverskoy, B.A.

    1999-01-01

    An analysis is presented for the implications of the relationship between the amplitude of the Dst variation and the position L max of the intensity maximum of the relativistic-electron belt that arises immediately after the cessation of a storm. The quantity L max is regarded to correspond to the position of the pressure maximum of the ring-current plasma at the moment of the maximum amplitude of the storm main phase. Under this assumption, the structure of the mentioned plasma formation is calculated, and the idea is substantiated that the plasma cloud is adiabatically driven deep into the magnetosphere during the sub-storm and subsequently symmetrized (this idea was originally put forward by the author on the basis of the theory of the magnetosphere-ionosphere interaction). It is shown that the presence of the mentioned relationship implies the existence of a certain boundary where the entropy calculated for a unit-magnetic-flux tube always has the same value. The applicability of the theory of low-pressure plasmas to the problem under study is justified

  7. Effects of Uncertainties in Electric Field Boundary Conditions for Ring Current Simulations

    Science.gov (United States)

    Chen, Margaret W.; O'Brien, T. Paul; Lemon, Colby L.; Guild, Timothy B.

    2018-01-01

    Physics-based simulation results can vary widely depending on the applied boundary conditions. As a first step toward assessing the effect of boundary conditions on ring current simulations, we analyze the uncertainty of cross-polar cap potentials (CPCP) on electric field boundary conditions applied to the Rice Convection Model-Equilibrium (RCM-E). The empirical Weimer model of CPCP is chosen as the reference model and Defense Meteorological Satellite Program CPCP measurements as the reference data. Using temporal correlations from a statistical analysis of the "errors" between the reference model and data, we construct a Monte Carlo CPCP discrete time series model that can be generalized to other model boundary conditions. RCM-E simulations using electric field boundary conditions from the reference model and from 20 randomly generated Monte Carlo discrete time series of CPCP are performed for two large storms. During the 10 August 2000 storm main phase, the proton density at 10 RE at midnight was observed to be low (Dst index is bounded by the simulated Dst values. In contrast, the simulated Dst values during the recovery phases of the 10 August 2000 and 31 August 2005 storms tend to underestimate systematically the observed late Dst recovery. This suggests a need to improve the accuracy of particle loss calculations in the RCM-E model. Application of this technique can aid modelers to make efficient choices on either investing more effort on improving specification of boundary conditions or on improving descriptions of physical processes.

  8. Electrostatic/magnetic ion acceleration through a slowly diverging magnetic nozzle between a ring anode and an on-axis hollow cathode

    Directory of Open Access Journals (Sweden)

    A. Sasoh

    2017-06-01

    Full Text Available Ion acceleration through a slowly diverging magnetic nozzle between a ring anode and a hollow cathode set on the axis of symmetry has been realized. Xenon was supplied as the propellant gas from an annular slit along the inner surface of the ring anode so that it was ionized near the anode, and the applied electric potential was efficiently transformed to an ion kinetic energy. As an electrostatic thruster, within the examined operation conditions, the thrust, F, almost scaled with the propellant mass flow rate; the discharge current, Jd, increased with the discharge voltage, Vd. An important characteristic was that the thrust also exhibited electromagnetic acceleration performance, i.e., the so-called “swirl acceleration,” in which F≅JdBRa ∕2, where B and Ra were a magnetic field and an anode inner radius, respectively. Such a unique thruster performance combining both electrostatic and electromagnetic accelerations is expected to be useful as another option for in-space electric propulsion in its broad functional diversity.

  9. Numerical simulation of dipolar magnetic field inflation due to equatorial ring-current

    International Nuclear Information System (INIS)

    Kajimura, Yoshihiro; Funaki, Ikkoh; Shinohara, Iku; Usui, Hideyuki; Matsumoto, Masaharu; Yamakawa, Hiroshi

    2014-01-01

    Magneto Plasma Sail (MPS) is one of the next generation space propulsion systems which generates a propulsive force using the interaction between the solar wind plasma and an artificial inflated magnetosphere generated by a superconductive coil. In the MPS system, the magnetosphere as a sail must be inflated by the plasma injection from the spacecraft in order to obtain the thrust gain. In the present study, the magnetic inflation concept is numerically tested by so-called ion one-component plasma model. As a simulation result, the magnetic moment of the system is drastically increased up to 45 times that of the coil current at plasma-β = 20 and r Li /L (radius of gyro motion / characteristics length of the magnetic field) = 0.01, and this is the first successful magnetosphere inflation obtained by numerical simulation. Corresponding maximum thrust gain is also estimated to be about 45. (author)

  10. Negative-ion current density dependence of the surface potential of insulated electrode during negative-ion implantation

    International Nuclear Information System (INIS)

    Tsuji, Hiroshi; Okayama, Yoshio; Toyota, Yoshitaka; Gotoh, Yasuhito; Ishikawa, Junzo; Sakai, Shigeki; Tanjyo, Masayasu; Matsuda, Kouji.

    1994-01-01

    Positive ion implantation has been utilized as the method of impurity injection in ultra-LSI production, but the problem of substrate charging cannot be resolved by conventional charge compensation method. It was forecast that by negative ion implantation, this charging problem can be resolved. Recently the experiment on the negative ion implantation into insulated electrodes was carried out, and the effect of negative ion implantation to this problem was proved. However, the dependence of charged potential on the increase of negative ion current at the time of negative ion implantation is a serious problem in large current negative ion implantation hereafter. The charged potential of insulated conductor substrates was measured by the negative ion implantation using the current up to several mA/cm 2 . The experimental method is explained. Medium current density and high current density negative ion implantation and charged potential are reported. Accordingly in negative ion implantation, if current density is optimized, the negative ion implantation without charging can be realized. (K.I.)

  11. Specific Noncovalent Association of Chiral Large-Ring Hexaimines: Ion Mobility Mass Spectrometry and PM7 Study.

    Science.gov (United States)

    Troć, Anna; Gajewy, Jadwiga; Danikiewicz, Witold; Kwit, Marcin

    2016-09-05

    Ion mobility mass spectrometry and PM7 semiempirical calculations are effective complementary methods to study gas phase formation of noncovalent complexes from vaselike macrocycles. The specific association of large-ring chiral hexaimines, derived from enantiomerically pure trans-1,2-diaminocyclohexane and various isophthaldehydes, is driven mostly by CH-π and π-π stacking interactions. The isotrianglimine macrocycles are prone to form two types of aggregates: tail-to-tail and head-to-head (capsule) dimers. The stability of the tail-to-tail dimers is affected by the size and electronic properties of the substituents at the C-5 position of the aromatic ring. Electron-withdrawing groups stabilize the aggregate, whereas bulky or electron-donating groups destabilize the complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Excitation of Ion Cyclotron Waves by Ion and Electron Beams in Compensated-current System

    Science.gov (United States)

    Xiang, L.; Wu, D. J.; Chen, L.

    2018-04-01

    Ion cyclotron waves (ICWs) can play important roles in the energization of plasma particles. Charged particle beams are ubiquitous in space, and astrophysical plasmas and can effectively lead to the generation of ICWs. Based on linear kinetic theory, we consider the excitation of ICWs by ion and electron beams in a compensated-current system. We also investigate the competition between reactive and kinetic instabilities. The results show that ion and electron beams both are capable of generating ICWs. For ICWs driven by ion beams, there is a critical beam velocity, v bi c , and critical wavenumber, k z c , for a fixed beam density; the reactive instability dominates the growth of ICWs when the ion-beam velocity {v}{bi}> {v}{bi}c and the wavenumber {k}zz≃ 2{k}zc/3 for a given {v}{bi}> {v}{bi}c. For the slow ion beams with {v}{bi}< {v}{bi}c, the kinetic instability can provide important growth rates of ICWs. On the other hand, ICWs driven by electron beams are excited only by the reactive instability, but require a critical velocity, {v}{be}c\\gg {v}{{A}} (the Alfvén velocity). In addition, the comparison between the approximate analytical results based on the kinetic theory and the exact numerical calculation based on the fluid model demonstrates that the reactive instabilities can well agree quantitatively with the numerical results by the fluid model. Finally, some possible applications of the present results to ICWs observed in the solar wind are briefly discussed.

  13. High current DC negative ion source for cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Etoh, H., E-mail: Hrh-Etoh@shi.co.jp; Aoki, Y.; Mitsubori, H.; Arakawa, Y.; Sakuraba, J.; Kato, T.; Mitsumoto, T.; Hiasa, T.; Yajima, S. [Sumitomo Heavy Industries, Ltd., Tokyo 141-6025 (Japan); Onai, M.; Hatayama, A. [Graduate School of Science and Technology, Keio University, Kanagawa 223-8522 (Japan); Shibata, T. [High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Okumura, Y. [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Aomori 039-3212 (Japan)

    2016-02-15

    A filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In Cs-free operation, continuous H{sup −} beam of 10 mA and D{sup −} beam of 3.3 mA were obtained stably at an arc-discharge power of 3 kW and 2.4 kW, respectively. In Cs-seeded operation, H{sup −} beam current reached 22 mA at a lower arc power of 2.6 kW with less co-extracted electron current. The optimum gas flow rate, which gives the highest H{sup −} current, was 15 sccm in the Cs-free operation, while it decreased to 4 sccm in the Cs-seeded operation. The relationship between H{sup −} production and the design/operating parameters has been also investigated by a numerical study with KEIO-MARC code, which gives a reasonable explanation to the experimental results of the H{sup −} current dependence on the arc power.

  14. High current transport experiment for heavy ion inertial fusion

    Directory of Open Access Journals (Sweden)

    L. R. Prost

    2005-02-01

    Full Text Available The High Current Experiment at Lawrence Berkeley National Laboratory is part of the U.S. program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ∼0.2  μC/m over long pulse durations (4  μs in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo, and electron and gas cloud effects. We present the results for a coasting 1 MeV K^{+} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius for which the transverse phase space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (≈80% is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  15. Three-dimensional ordering of cold ion beams in a storage ring: A molecular-dynamics simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Yuri, Yosuke, E-mail: yuri.yosuke@jaea.go.jp [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi Takasaki, Gunma 370-1292 Japan (Japan)

    2015-06-29

    Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points.

  16. Emittance variations in current-amplifying ion induction linacs

    International Nuclear Information System (INIS)

    Fessenden, T.J.

    1991-01-01

    Since 1985 the Heavy Ion Fusion Accelerator Research program at the Lawrence Berkeley Laboratory has been studying current amplification and emittance variations in MBE-4, a four-cesium-beam induction linac. This experiment models much of the accelerator physics of the electrostatically focused section of a fusion driver. Four space-charge dominated Cs + beams, initially about one meter in length at currents of 5-10 mA, are focused by electrostatic quadrupoles and accelerated in parallel from approximately 200 keV up to one MeV by 24 accelerating gaps. Final currents of 20-40 mA per beam are typical. Recent experiments with extremely low emittance beams (var-epsilon n =0.03 mm-mRad) have investigated variations of transverse and longitudinal normalized emittance for drifting and accelerating beams. These very strongly tune-depressed beams (σ 0 =72 degree, σ∼6 degree) are difficult to match to the accelerator so as to avoid emittance growth during acceleration. During transport strong emittance fluctuations are observed in good qualitative agreement with simulations. Warmer beams with less tune depression exhibit little to no emittance growth, show smaller emittance fluctuations, and are much easier to match. A summary of findings from the MBE-4 studies is presented

  17. Emittance variations in current-amplifying ion induction linacs

    International Nuclear Information System (INIS)

    Fessenden, T.J.

    1991-04-01

    Since 1985 the Heavy Ion Fusion Accelerator Research program at the Lawrence Berkeley Laboratory has been studying current amplification and emittance variations in MBE-4, a four-cesium-beam induction linac. This experiment models much of the accelerator physics of the electrostatically focused section of a fusion driver. Four space-charge dominated Cs + beams, initially about one meter in length at currents of 5--10 mA, are focused by electrostatic quadrupoles and accelerated in parallel from approximately 200 keV up to one MeV by 24 accelerating gaps. Final currents of 20--40 mA per beam are typical. Recent experiments with extremely low emittance beams (ε n = 0.03 mm-mRad) have investigated variations of transverse and longitudinal normalized emittance for drifting and accelerating beams. These very strongly tune-depressed beams (σ o = 72 degrees, σ∼6 degree) are difficult to match the accelerator so as to avoid emittance growth during acceleration. During transport strong emittance fluctuations are observed in good qualitative agreement with simulations. Warmer beams with less tune depression exhibit little to no emittance growth, show smaller emittance fluctuations, and are much easier to match. A summary of findings from the MBE-4 studies is presented. 12 refs., 8 figs

  18. Simulations of Bunch Precompression at High Currents in the SLC Damping Rings

    International Nuclear Information System (INIS)

    Bane, K.L.F.; Minty, M.G.; Chao, A.W.

    2011-01-01

    In the Stanford Linear Collider (SLC) each beam, after leaving a damping ring, is compressed in the Ring-to-Linac (RTL) transfer line before entering the linear accelerator. At a bunch population of 4.0 x 10 10 particles, due to the limited energy acceptance of the RTL, approximately 15% of the beam has normally been lost. During the 1996 run, however, to eliminate this loss the bunch was partially precompressed in the damping ring, just before extraction; the beam loss in the RTL was reduced to almost zero. The operation and performance of precompression are presented by Minty et al. (1999). Also given is an analysis which, however, does not include the effects of the longitudinal wakefield on the beam dynamics. In this report we extend that analysis to include these effects.

  19. The Locations of Ring Current Pressure Peaks: Comparison of TWINS Measurements and CIMI Simulations for the 7-10 September 2015 CIR Storm

    Science.gov (United States)

    Hill, S. C.; Edmond, J. A.; Xu, H.; Perez, J. D.; Fok, M. C. H.; Goldstein, J.; McComas, D. J.; Valek, P. W.

    2017-12-01

    The characteristics of a four day 7-10 September 2015 co-rotating interaction region (CIR) storm (min. SYM/H ≤ -110 nT) are categorized by storm phase. Ion distributions of trapped particles in the ring current as measured by the Two Wide-Angle Imaging Neutral Atom Spectrometers (TWINS) are compared with the simulated ion distributions of the Comprehensive Inner Magnetosphere-Ionosphere Model (CIMI). The energetic neutral atom (ENA) images obtained by TWINS are deconvolved to extract equatorial pitch angle, energy spectra, ion pressure intensity, and ion pressure anisotropy distributions in the inner magnetosphere. CIMI, using either a self-consistent electric field or a semi-empirical electric field, simulates comparable distributions. There is good agreement between the data measured by TWINS and the different distributions produced by the self-consistent electric field and the semi-empirical electric field of CIMI. Throughout the storm the pitch angle distribution (PAD) is mostly perpendicular in both CIMI and TWINS and there is agreement between the anisotropy distributions. The locations of the ion pressure peaks seen by TWINS and by the self-consistent and semi empirical electric field parameters in CIMI are usually between dusk and midnight. On average, the self-consistent electric field in CIMI reveals ion pressure peaks closer to Earth than its semi empirical counterpart, while TWINS reports somewhat larger radial values for the ion pressure peak locations. There are also notable events throughout the storm during which the simulated observations show some characteristics that differ from those measured by TWINS. At times, there are ion pressure peaks with magnetic local time on the dayside and in the midnight to dawn region. We discuss these events in light of substorm injections indicated by fluctuating peaks in the AE index and a positive By component in the solar wind. There are also times in which there are multiple ion pressure peaks. This may

  20. A Long-term Ring Current Measure Created by Using the VMO MANGO Service Package

    Science.gov (United States)

    Bargatze, L. F.; King, T. A.

    2008-12-01

    A set of computational routines called MANGO (Magnetogram Analysis for the Network of Geomagnetic Observatories) is utilized to calculate a new measure of magnetic storm activity for the years 1932 to the near present. The MANGO routines are part of an effort to enhance data services available to users of the Heliophysics VxOs, specifically for the Virtual Magnetospheric Observatory (VMO). The community can utilize MANGO to derive value-added data products and images suitable for publication via the VMO web site. MANGO routines will be demonstrated through their application to study magnetic storms, a field of research that began in 1828 when von Humboldt launched an investigation of observations taken simultaneously from magnetic field stations spread around the Earth. The defining signature of magnetic storms is a worldwide decrease of the horizontal component of the magnetic field caused by fluctuations in the strength of the ring current. In the 1940's, Bartel pushed for deriving an index to measure the strength of magnetic storms. Progress intensified during the International Geophysical Year leading to the definition of the Dst index. The definitive Dst index is calculated at WDC-C2 for Geomagnetism in Kyoto by using a derivation scheme certified by Division V of IAGA. The Dst index time series spans the years 1957 to present with a cadence equal to 1-hr. The new data set we will present is a magnetic storm measure that is similar to the Dst index though it is calculated by using MANGO and a method that differs slightly from the official scheme. The MANGO data service package is based on a set of IDL routines that decompose ground magnetic field observations to isolate secular, diurnal, and disturbance variations of the magnetic field station-by-station. Each MANGO subroutine has been written in modular fashion to allow "plug and play"- style flexibility and each has been designed to account for failure modes and noisy data so that the programs will run to

  1. Effects of increasing number of rings on the ion sensing ability of CdSe quantum dots: a theoretical study

    Science.gov (United States)

    Malik, Pragati; Kakkar, Rita

    2018-04-01

    A computational study on the structural and electronic properties of a special class of artificial atoms, known as quantum dots, has been carried out. These are semiconductors with unique optical and electronic properties and have been widely used in various applications, such as bio-sensing, bio-imaging, and so on. We have considered quantum dots belonging to II-VI types of semiconductors, due to their wide band gap, possession of large exciton binding energies and unique optical and electronic properties. We have studied their applications as chemical ion sensors by beginning with the study of the ion sensing ability of (CdSe) n ( n = 3, 6, 9 which are in the size range of 0.24, 0.49, 0.74 nm, respectively) quantum dots for cations of the zinc triad, namely Zn2+, Cd2+, Hg2+, and various anions of biological and environmental importance, and studied the effect of increasing number of rings on their ion sensing ability. The various structural, electronic, and optical properties, their interaction energies, and charge transfer on interaction with metal ions and anions have been calculated and reported. Our studies indicate that the CdSe quantum dots can be employed as sensors for both divalent cations and anions, but they can sense cations better than anions.

  2. Generation of geometrical phases and persistent spin currents in 1-dimensional rings by Lorentz-violating terms

    Energy Technology Data Exchange (ETDEWEB)

    Casana, R.; Ferreira, M.M., E-mail: manojr.ufma@gmail.com; Mouchrek-Santos, V.E.; Silva, Edilberto O.

    2015-06-30

    We have demonstrated that Lorentz-violating terms stemming from the fermion sector of the SME are able to generate geometrical phases on the wave function of electrons confined in 1-dimensional rings, as well as persistent spin currents, in the total absence of electromagnetic fields. We have explicitly evaluated the eigenenergies and eigenspinors of the electrons modified by the Lorentz-violating terms, using them to calculate the dynamic and the Aharonov–Anandan phases in the sequel. The total phase presents a pattern very similar to the Aharonov–Casher phase accumulated by electrons in rings under the action of the Rashba interaction. Finally, the persistent spin current were carried out and used to impose upper bounds on the Lorentz-violating parameters.

  3. On the energy dependence of the relative contributions ionospheric and solar sources of the ring current protons

    International Nuclear Information System (INIS)

    Kovtyukh, A.

    2007-01-01

    The energy dependence of a fraction of ring current protons of i onospheric origin is calculated using the AMPTE/CCE data for a typical magnetic storm (D st = -120 nT). It is shown that at L = 6-7 (L is the Mcllwain parameter) this fraction monotonically decreases from ∼83 to 25-30% with an increase in proton energy from 5 to 315 keV and is 30-40% at energy 40-50 keV corresponding to the maximum of proton energy density at L 6-7. It is evident that the core of the ring current (L = 3.7-4.7) is enriched by solar protons with E∼10-200 keV during storm main phase (the maximum effect is achieved at E∼20-50 keV). (author)

  4. A short review of our current understanding of the development of ring faults during collapse caldera formation

    Directory of Open Access Journals (Sweden)

    Adelina eGeyer

    2014-09-01

    Full Text Available The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

  5. Combined convective and diffusive modeling of the ring current and radiation belt electron dynamics using the VERB-4D code

    Science.gov (United States)

    Aseev, N.; Shprits, Y.; Drozdov, A.; Kellerman, A. C.; Wang, D.

    2017-12-01

    Ring current and radiation belts are key elements in the global dynamics of the Earth's magnetosphere. Comprehensive mathematical models are useful tools that allow us to understand the multiscale dynamics of these charged particle populations. In this work, we present results of simulations of combined ring current - radiation belt electron dynamics using the four-dimensional Versatile Electron Radiation Belt (VERB-4D) code. The VERB-4D code solves the modified Fokker-Planck equation including convective terms and models simultaneously ring current (1 - 100 keV) and radiation belt (100 keV - several MeV) electron dynamics. We apply the code to the number of geomagnetic storms that occurred in the past, compare the results with different satellite observations, and show how low-energy particles can affect the high-energy populations. Particularly, we use data from Polar Operational Environmental Satellite (POES) mission that provides a very good MLT coverage with 1.5-hour time resolution. The POES data allow us to validate the approach of the VERB-4D code for modeling MLT-dependent processes such as electron drift, wave-particle interactions, and magnetopause shadowing. We also show how different simulation parameters and empirical models can affect the results, making a particular emphasis on the electric and magnetic field models. This work will help us reveal advantages and disadvantages of the approach behind the code and determine its prediction efficiency.

  6. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, S.A.; Puzynin, I.V.; Samoilov, V.N.; Sissakian, A.N. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)

    1997-09-01

    The project of a high current pulsed linear ion accelerator is described in this paper. The accelerator consists of an ion injector, a system of charge and energy separation, an inductor accelerator and an output system. The ion source with explosive ion emission can produce all kinds of ions. The separation system includes a pulsed magnetic system. The inductors are based on amorphous iron with inside magnetic elements. 3 refs., 3 figs.

  7. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    International Nuclear Information System (INIS)

    Korenev, S.A.; Puzynin, I.V.; Samoilov, V.N.; Sissakian, A.N.

    1997-01-01

    The project of a high current pulsed linear ion accelerator is described in this paper. The accelerator consists of an ion injector, a system of charge and energy separation, an inductor accelerator and an output system. The ion source with explosive ion emission can produce all kinds of ions. The separation system includes a pulsed magnetic system. The inductors are based on amorphous iron with inside magnetic elements. 3 refs., 3 figs

  8. Characterization and control of wafer charging effects during high-current ion implantation

    International Nuclear Information System (INIS)

    Current, M.I.; Lukaszek, W.; Dixon, W.; Vella, M.C.; Messick, C.; Shideler, J.; Reno, S.

    1994-02-01

    EEPROM-based sense and memory devices provide direct measures of the charge flow and potentials occurring on the surface of wafers during ion beam processing. Sensor design and applications for high current ion implantation are discussed

  9. Transmission line component testing for the ITER Ion Cyclotron Heating and Current Drive System

    Science.gov (United States)

    Goulding, Richard; Bell, G. L.; Deibele, C. E.; McCarthy, M. P.; Rasmussen, D. A.; Swain, D. W.; Barber, G. C.; Barbier, C. N.; Cambell, I. H.; Moon, R. L.; Pesavento, P. V.; Fredd, E.; Greenough, N.; Kung, C.

    2014-10-01

    High power RF testing is underway to evaluate transmission line components for the ITER Ion Cyclotron Heating and Current Drive System. The transmission line has a characteristic impedance Z0 = 50 Ω and a nominal outer diameter of 305 mm. It is specified to carry up to 6 MW at VSWR = 1.5 for 3600 s pulses, with transient voltages up to 40 kV. The transmission line is actively cooled, with turbulent gas flow (N2) used to transfer heat from the inner to outer conductor, which is water cooled. High voltage and high current testing of components has been performed using resonant lines generating steady state voltages of 35 kV and transient voltages up to 60 kV. A resonant ring, which has operated with circulating power of 6 MW for 1 hr pulses, is being used to test high power, low VSWR operation. Components tested to date include gas barriers, straight sections of various lengths, and 90 degree elbows. Designs tested include gas barriers fabricated from quartz and aluminum nitride, and transmission lines with quartz and alumina inner conductor supports. The latest results will be presented. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.

  10. Cyclopeptide alkaloids. Synthesis of the ring system and its ion affinity

    International Nuclear Information System (INIS)

    Lagarias, J.C.; Houghten, R.A.; Rapoport, H.

    1978-01-01

    Several examples of the 14-membered, para-bridged ring system of the cyclopeptide alkaloids have been synthesized via an active ester cyclization. The yield of monomeric cyclopeptide varied from 1 to 33% and was affected by the amino acid substitution pattern and amide conformation of the linear peptide precursors. Both the synthetic models and a naturally occurring cyclopeptide alkaloid, ceanothine B, bind monovalent (Li + ) and divalent (Ca 2+ , Mg 2+ ) cations. 4 figures, 1 table

  11. Heavy Ion Current Transients in SiGe HBTs

    Science.gov (United States)

    Pellish, Jonathan A.; Reed, Robert A.; Vizkelethy, Gyorgy; McMorrow, Dale; Ferlet-Cavrois, Veronique; Baggio, Jacques; Paillet, Philipe; Duhanel, Olivier; Phillips, Stanley D.; Sutton, Akil K.; hide

    2009-01-01

    Time-resolved ion beam induced charge reveals heavy ion response of IBM 5AM SiGe HBT: a) Position correlation[ b) Unique response for different bias schemes; c) Similarities to TPA pulsed-laser data. Heavy ion broad-beam transients provide more realistic device response: a) Feedback using microbeam data; b) Overcome issues of LET and ion range with microbeam. Both micro- and broad-beam data sets yield valuable input for TCAD simulations. Uncover detailed mechanisms for SiGe HBTs and other devices fabricated on lightly-doped substrates.

  12. Picomolar detection limits with current-polarized Pb2+ ion-selective membranes.

    Science.gov (United States)

    Pergel, E; Gyurcsányi, R E; Tóth, K; Lindner, E

    2001-09-01

    Minor ion fluxes across ion-selective membranes bias submicromolar activity measurements with conventional ion-selective electrodes. When ion fluxes are balanced, the lower limit of detection is expected to be dramatically improved. As proof of principle, the flux of lead ions across an ETH 5435 ionophore-based lead-selective membrane was gradually compensated by applying a few nanoamperes of galvanostatic current. When the opposite ion fluxes were matched, and the undesirable leaching of primary ions was eliminated, Nernstian response down to 3 x 10(-12) M was achieved.

  13. Quantum nano ring composed of quantum dots as a source of pure persistent spin or charge current

    International Nuclear Information System (INIS)

    Eslami, L.; Faizabadi, E.; Ahmadi, S.

    2016-01-01

    Spin-dependent persistent current in a quantum ring constituted by two normal and one magnetic quantum dots, in the presence of Rashba spin–orbit interaction is studied by using Green function technique. It is shown that the presence of the magnetic quantum dot breaks the degeneracy of the density of states of electrons with different spin states. Besides, the Rashba spin–orbit interaction along with the magnetic quantum dot develops tunable persistent spin and charge currents. Moreover, the persistent charge current induces a fully adjustable magnetic flux whose direction and magnitude can be tuned by altering the strength of the Rashba spin–orbit interaction. - Highlights: • An array of normal and magnetic quantum dots with Rashba effect is studied. • Spin-dependent persistent current and DOS are studied using Green function method. • The magnetic quantum dot breaks degeneracy of DOS of up and down spin electrons. • The persistent spin and charge currents are tuned by adjusting the Rashba constant. • The persistent charge current induces tunable magnetic field at the center of ring.

  14. Persistent current in triangle silicene rings with spin–orbit interaction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ning, E-mail: nxu@ycit.cn [Department of Physics, Yancheng Institute of Technology, Yancheng 224051 (China); Zhang, Haiyang; Wu, Xiuqiang; Bai, Yujie [Department of Physics, Yancheng Institute of Technology, Yancheng 224051 (China); Ding, Jianwen, E-mail: jwding@xtu.edu.cn [Department of Physics, Xiangtan University, Xiangtan 411105 (China)

    2017-06-28

    The energy spectrum and magnetic response of triangle silicene rings (TSRs) are investigated within the tight-binding model. It is shown that the flux-dependent energy spectrum is divided into bands, with three levels per band, owing to the three-fold rotational symmetry structure of TSRs. The zigzag TSRs are metallic, exhibiting either diamagnetic or paramagnetic response depending on the size of inner ring radius. Armchair TSRs are semiconducting, exhibiting diamagnetic response. Taking into account the intrinsic spin–orbit interaction, the magnetic-field-driven spin-up electrons flow anticlockwise around the TSRs and the spin-down electrons flow clockwise around the TSRs. Additionally, paramagnetism–diamagnetism or diamagnetism–paramagnetism transitions are observed with the increase of exchange field. The results may be very helpful for the design and application of TSR-based nanodevices. - Highlights: • The zigzag TSRs are metallic. • Armchair TSRs which exhibit diamagnetic response are semiconducting. • The spin-up electrons flow anticlockwise and spin-down electrons flow clockwise around the rings.

  15. Analysis of the wake field effects in the PEP-II storage rings with extremely high currents

    Energy Technology Data Exchange (ETDEWEB)

    Novokhatski, A., E-mail: novo@slac.stanford.edu; Seeman, J.; Sullivan, M.

    2014-01-21

    We present the history and analysis of different wake field effects throughout the operational life of the PEP-II SLAC B-factory. Although the impedance of the high and low energy rings is small, the intense high-current beams generated a lot of power. The effects from these wake fields are: heating and damage of vacuum beam chamber elements like RF seals, vacuum valves, shielded bellows, BPM buttons and ceramic tiles; vacuum spikes, vacuum instabilities and high detector background; and beam longitudinal and transverse instabilities. We also discuss the methods used to eliminate these effects. Results of this analysis and the PEP-II experience may be very useful in the design of new storage rings and light sources.

  16. Experimental observation of current generation by asymmetrical heating of ions in a tokamak plasma

    International Nuclear Information System (INIS)

    Gahl, J.; Ishihara, O.; Wong, K.L.; Kristiansen, M.; Hagler, M.

    1986-01-01

    The first experimental observation of current generation by asymmetrical heating of ions is reported. Ions were asymmetrically heated by a unidirectional fast Alfven wave launched by a slow wave antenna inside a tokamak. Current generation was detected by measuring the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column

  17. Guiding of slow Ne7+ ions through nanocapillaries in insulating polyethylene terephthalate: Incident current dependence

    International Nuclear Information System (INIS)

    Stolterfoht, N.; Hellhammer, R.; Bundesmann, J.; Fink, D.; Kanai, Y.; Kambara, T.; Ikeda, T.; Hoshino, M.; Yamazaki, Y.

    2007-01-01

    The transmission of highly charged ions through nanocapillaries in insulating polyethylene terephthalate (PET) polymers was investigated. In experiments at laboratories in RIKEN (Japan) and HMI (Germany) different detection methods were applied to study the ion current dependence in a wide range covering two orders of magnitude. At HMI an electrostatic ion spectrometer was used and at RIKEN a two-dimensional position sensitive detector was implemented. New PET samples with parallel capillaries and low density were manufactured. For tilted capillaries, the ions are guided along the capillary axis, since the majority of ions are deflected in a charge patch created in the capillary entrance. The results provide insights into the mechanisms of capillary guiding. The fraction of transmitted ions was found to be nearly independent on the incident ion current indicating a sudden increase in the discharge current depleting the entrance charge patch. The experimental results were well-reproduced by model calculations based on a nonlinear (exponential) expression for the discharge current

  18. Operating experience with high beam currents and transient beam loading in the SLC damping rings

    International Nuclear Information System (INIS)

    Minty, M.G.; Akre, R.; Krejcik, P.; Siemann, R.H.

    1995-01-01

    During the 1994 SLC run the nominal operating intensity in the damping rings was raised from 3.5 x 10 10 to greater than 4 x 10 10 particles per bunch (ppb). Stricter regulation of rf system parameters was required to maintain stability of the rf system and particle beam. Improvements were made in the feedback loops which control the cavity amplitude and loading angles. Compensation for beam loading was also required to prevent klystron saturation during repetition rate changes. To minimize the effects of transient loading on the rf system, the gain of the direct rf feedback loop and the loading angles were optimized

  19. Spin dynamics in mesoscopic size magnetic systems: A 1HNMR study in rings of iron (III) ions

    International Nuclear Information System (INIS)

    Lascialfari, A.; Gatteschi, D.; Borsa, F.; Cornia, A.

    1997-01-01

    Two magnetic molecular clusters containing almost coplanar rings of iron (III) ions with spinS=5/2 have been investigated by 1 H NMR and relaxation measurements. The first system, which will be referred to as Fe6, is a molecule of general formula [NaFe 6 (OCH 3 ) 12 (C 17 O 4 H 15 ) 6 ] + ClO 4 - or [NaFe 6 (OCH 3 ) 12 (C 15 H 11 O 2 ) 6 ] + ClO 4 - or [LiFe 6 (OCH 3 ) 12 (C 15 H 11 O 2 ) 6 ] + ClO 4 - while the second type of ring, denoted Fe10, corresponds to the molecule [Fe 10 (OCH 3 ) 20 (C 2 H 2 O 2 Cl) 10 ]. The 1 H NMR linewidth is broadened by the nuclear dipolar interaction and by the dipolar coupling of the protons with the iron (III) paramagnetic moment. It is found that the nuclear spin-lattice relaxation rate, T 1 -1 , of the proton is a sensitive probe of the Fe spin dynamics. In both clusters, T 1 -1 decreases with decreasing temperatures from room temperature, goes through a peak just below about 30 K in Fe6 and 10 K in Fe10, and it drops exponentially to very small values at helium temperature. The temperature dependence of the relaxation rate is discussed in terms of the fluctuations of the local spins within the allowed total spin configurations in the framework of the weak collision theory to describe the nuclear relaxation. We use the calculated energy levels for the Fe6 ring based on a Heisenberg Hamiltonian and the value of J obtained from the fit of the magnetic susceptibility to describe semiquantitatively the behavior of T 1 -1 vs T. The exponential drop of T 1 -1 at low temperature is consistent with a nonmagnetic singlet ground state separated by an energy gap from the first excited triplet state. (Abstract Truncated)

  20. Beam Current Increase and Cathode Lifetime Improvement of KOTRON-13 Ion Source

    International Nuclear Information System (INIS)

    Lee, W. K.; Chae, S. K.; Song, J. Y.; Im, G. S.; Cho, B. O.

    2010-01-01

    Technology of cyclotron has been actively developed to meet the increasing requirement output of medical radioactive isotopes for PET. KOTRON-13 is produced with low negative hydrogen ion beam current owing to the low efficiency of proton beam current compared with foreign cyclotron. In the defect there from, the lifetime of cathode is around 5,000min, which requires frequent maintenance period, and the target beam current is maximum 50uA at a poor efficiency compared with the inflow quantity of hydrogen gas and that of inflicting arc current. Considering above affairs, we have to improve the PIG ion source extraction efficiency of KOTRON-13 in order to lift beam current. Mostly the ion source of cyclotron less than 30Mev comes from the use of PIG ion source mainly with the method of cold cathode or hot cathode. However, the cyclotron of 30Mev grade of EBCO or IBA uses the external ion source and uses ion source with cusp type of good withdrawal efficiency. This type requires high voltage, and transports ion from ion source to cyclotron, which requires precise transportation equipment. And entering cyclotron requires a high quality of inflictor with a high defect rate, but high current cyclotron has no choice but to use ion source of such a method. But the cyclotron using PET with the beam current less than 100uA uses PIG ion source of KOTRON-13 with a reasonable maintenance cost

  1. A lattice-gas model of the ion current across the solid interface: fast-ion conductor - intercalate

    International Nuclear Information System (INIS)

    Nachev, I.; Balkanski, M.

    1994-12-01

    The transport of Lithium ions across the material interface: fast-ion conducting glass - intercalate is simulated by a non-trivial lattice-gas model. The model takes explicitly into account the influence of the Coulomb correlations, the site-blocking effect and the boundary conditions on the ion kinetics. Potential device applications of the model are pointed out by computing the current density of Lithium ions for material parameters of the real interface: doped ternary borate glass - Indium Selenide, which constitute the electrolyte and the cathode, respectively, of a thin-film microbattery with improved performance. (author). 10 refs, 4 figs

  2. Determination of corrosion rate of reinforcement with a modulated guard ring electrode; analysis of errors due to lateral current distribution

    International Nuclear Information System (INIS)

    Wojtas, H.

    2004-01-01

    The main source of errors in measuring the corrosion rate of rebars on site is a non-uniform current distribution between the small counter electrode (CE) on the concrete surface and the large rebar network. Guard ring electrodes (GEs) are used in an attempt to confine the excitation current within a defined area. In order to better understand the functioning of modulated guard ring electrode and to assess its effectiveness in eliminating errors due to lateral spread of current signal from the small CE, measurements of the polarisation resistance performed on a concrete beam have been numerically simulated. Effect of parameters such as rebar corrosion activity, concrete resistivity, concrete cover depth and size of the corroding area on errors in the estimation of polarisation resistance of a single rebar has been examined. The results indicate that modulated GE arrangement fails to confine the lateral spread of the CE current within a constant area. Using the constant diameter of confinement for the calculation of corrosion rate may lead to serious errors when test conditions change. When high corrosion activity of rebar and/or local corrosion occur, the use of the modulated GE confinement may lead to significant underestimation of the corrosion rate

  3. Current experimental situation in heavy-ion reactions

    International Nuclear Information System (INIS)

    Scott, D.K.

    1978-06-01

    A detailed survey of the present experimental situation in heavy-ion physics is presented. The discussion begins by considering the simple excitation of discrete states in elastic scattering, transfer, and compound-nucleus reactions; it then turns to more drastic perturbations of the nucleus high in the continuum through fusion, fission, and deeply inelastic scattering, and concludes with the (possibly) limiting asymptotic phenomena of relativistic heavy-ion collisions. 138 figures, 5 tables, 451 references

  4. OPENMED: A facility for biomedical experiments based on the CERN Low Energy Ion Ring (LEIR)

    Science.gov (United States)

    Carli, Christian

    At present protons and carbon ions are in clinical use for hadron therapy at a growing number of treatment centers all over the world. Nevertheless, only limited direct clinical evidence of their superiority over other forms of radiotherapy is available [1]. Furthermore fundamental studies on biological effects of hadron beams have been carried out at different times (some a long time ago) in different laboratories and under different conditions. Despite an increased availability of ion beams for hadron therapy, beam time for preclinical studies is expected to remain insufficient as the priority for therapy centers is to treat the maximum number of patients. Most of the remaining beam time is expected to be required for setting up and measurements to guarantee appropriate good quality beams for treatments. The proposed facility for biomedical research [2] in support of hadron therapy centers would provide ion beams for interested research groups and allow them to carry out basic studies under well defined conditions. Typical studies would include radiobiological phenomena like relative biological effectiveness with different energies, ion species, and intensities. Furthermore possible studies include the development of advanced dosimetry in heterogeneous materials that resemble the human body, imaging techniques and, at a later stage, when the maximum energy with the LEIR magnets can be reached, fragmentation.

  5. Field-reversing electron and ion rings for the confinement and heating of plasmas. Annual progress report, October 1, 1985-September 30, 1986

    International Nuclear Information System (INIS)

    Fleischmann, H.H.

    1986-10-01

    During the present, second period of our contract, the effort of our RECE-group was focussed mainly in four areas: (1) the design and construction of our new main experimental device, the megavolt ion coil experiment (MICE, aimed at generating 1-MeV ion rings) was continued. The device construction was completed and injection experiments recently have started using a half-cusp arrangement. (2) Using our smaller MERGE device (500 keV electrons, cusp injection), we investigated as expected the precessional stabilization of strong electron rings by a resistive wall. As expected, the experiments are completed. The results show excellent agreement with the basic theoretical expectations of our earlier analytic calculations and also with a more detailed computer code recently compiled. (3) Also, our MERGE device was completed as expected; experiments showed successful generation of electron and plasma rings; first experiments on the merging of these rings show a rapid attraction between the rings, which is to be properly slowed down by the introduction of a resistive wall. (4) Our pilot model calculations on mixed-CT configurations were nearly completed; including a survey of relevant plasma ring equilibria with a strong large-orbit particle components. Rough stability limits were obtained by studying the magnetic interaction between the two components

  6. Novel Faraday cup for the simultaneous observation and measurement of ion-beam currents

    International Nuclear Information System (INIS)

    Wei, C.; Seidman, D.N.

    1977-01-01

    A novel Faraday cup is described which allows the simultaneous observation and measurement of ion-beam currents. The Faraday cup is constructed around a Galileo channel electron multiplier array (CEMA), which serves as the basis of an internal image intensification system (a gain of >10 4 ) for the observation of the ion beam; the CEMA also acts as a collector for the ion current which is measured by a Keithley 602 electrometer. The ion current is integrated by a simple and inexpensive dosimeter; the electronic circuit for the dosimeter is described. The application of the Faraday cup to the observation and measurement of a 30-keV Ar + ion beam is presented as an illustrative example. We have also employed this Faraday cup to observe and measure 30-keV Cr + , Mo + , or W + , and 18-keV Au + ion beams employed for the in situ irradiation of field-ion microscope specimens

  7. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, S A; Puzynin, I V; Samojlov, V N; Sissakyan, A N [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    1997-12-31

    A new high-current pulsed linear induction accelerator proposed for application in beam-driven transmutation technologies is described. The accelerator consists of an ion injector, of ion separation and induction accelerating systems, and of an output system for extracting an ion beam into open air. An ion source with explosive ion emission, capable of producing various kinds of ions, is used as an injector. The ion separator exploits a pulsed magnetic system. The induction acceleration structure includes inductors with amorphous iron cores. Imbedded magnetic elements assure the ion beam transport. Main parameters of the accelerator are given in the paper and the design of an ion injector is discussed in more detail. (J.U.). 3 figs., 3 refs.

  8. High current pulsed ion inductor accelerator for destruction of radioactive wastes

    International Nuclear Information System (INIS)

    Korenev, S.A.; Puzynin, I.V.; Samojlov, V.N.; Sissakyan, A.N.

    1996-01-01

    A new high-current pulsed linear induction accelerator proposed for application in beam-driven transmutation technologies is described. The accelerator consists of an ion injector, of ion separation and induction accelerating systems, and of an output system for extracting an ion beam into open air. An ion source with explosive ion emission, capable of producing various kinds of ions, is used as an injector. The ion separator exploits a pulsed magnetic system. The induction acceleration structure includes inductors with amorphous iron cores. Imbedded magnetic elements assure the ion beam transport. Main parameters of the accelerator are given in the paper and the design of an ion injector is discussed in more detail. (J.U.). 3 figs., 3 refs

  9. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    International Nuclear Information System (INIS)

    Haseroth, Helmut; Hora, Heinrich; Regensburg Inst. of Tech.

    1996-01-01

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10 11 C 4+ ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ''hot'' electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author)

  10. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Haseroth, Helmut [European Organization for Nuclear Research, Geneva (Switzerland); Hora, Heinrich [New South Wales Univ., Kensington, NSW (Australia)]|[Regensburg Inst. of Tech. (Germany). Anwenderzentrum

    1996-12-31

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10{sup 11} C{sup 4+} ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ``hot`` electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author).

  11. Photophysical property of rhodamine-cored poly(amidoamine) dendrimers: Simultaneous effect of spirolactam ring-opening and PET process on sensing trivalent chromium ion

    International Nuclear Information System (INIS)

    Lei Yonglin; Su Yuanqiang; Huo Jichuan

    2011-01-01

    Two novel poly(amidoamine) (PAMAM) dendrimers, comprising rhodamine B unit in the core and 1-phenyl-3-methyl-5-pyrazolone unit at the periphery, have been synthesized and characterized. Both dendrimers displayed high selectivity and sensitivity towards Cr 3+ ion. As considering the potential of being applied as fluorescent sensors for Cr 3+ ion, we studied the complexes formed between the dendrimers and Cr 3+ ion. Different PAMAM dendrimers had different recognition mechanism towards Cr 3+ ion. For dendrimer G2, the recognition of Cr 3+ was mainly due to the ring-opening of spirolactam. However, it significantly depended on the simultaneous effect of ring-opening of spirolactam and photoinduced electron transfer (PET) in the case of dendrimer G3. - Highlights: → First synthesize two novel PAMAM simultaneously containing rhodamine and pyrazolone. → Novel dendrimer show high selectivity and sensitivity towards Cr 3+ . → Recognition Cr 3+ of dendrimer G2 is dominantly due to the ring-opening mechanism. → Sensing Cr 3+ of dendrimer G3 is dependent on simultaneous mechanisms of ring-opening and PET.

  12. High-current negative hydrogen ion beam production in a cesium-injected multicusp source

    International Nuclear Information System (INIS)

    Takeiri, Y.; Tsumori, K.; Kaneko, O.

    1997-01-01

    A high-current negative hydrogen ion source has been developed, where 16.2 A of the H - current was obtained with a current density of 31 mA/cm 2 . The ion source is a multicusp source with a magnetic filter for negative ion production, and cesium vapor is injected into the arc chamber, leading to enhancement of the negative ion yields. The cesium-injection effects are discussed, based on the experimental observations. Although the surface production of the negative ions on the cesium-covered plasma grid is thought to be a dominant mechanism of the H - current enhancement, the cesium effects in the plasma volume, such as the cesium ionization and the electron cooling, are observed, and could contribute to the improved operation of the negative ion source. (author)

  13. THE IBEX RIBBON AND THE PICKUP ION RING STABILITY IN THE OUTER HELIOSHEATH. II. MONTE-CARLO AND PARTICLE-IN-CELL MODEL RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Niemiec, J. [Institute of Nuclear Physics PAN, Radzikowskiego 152 31-342 Krakow (Poland); Florinski, V.; Heerikhuisen, J. [Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Nishikawa, K.-I., E-mail: jacek.niemiec@ifj.edu.pl, E-mail: vaf0001@uah.edu, E-mail: jh0004@uah.edu, E-mail: ken-ichi.nishikawa-1@nasa.gov [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2016-08-01

    The nearly circular ribbon of energetic neutral atom (ENA) emission discovered by NASA’s Interplanetary Boundary EXplorer satellite ( IBEX ), is most commonly attributed to the effect of charge exchange of secondary pickup ions (PUIs) gyrating about the magnetic field in the outer heliosheath (OHS) and the interstellar space beyond. The first paper in the series (Paper I) presented a theoretical analysis of the pickup process in the OHS and hybrid-kinetic simulations, revealing that the kinetic properties of freshly injected proton rings depend sensitively on the details of their velocity distribution. It was demonstrated that only rings that are not too narrow (parallel thermal spread above a few km s{sup −1}) and not too wide (parallel temperature smaller than the core plasma temperature) could remain stable for a period of time long enough to generate ribbon ENAs. This paper investigates the role of electron dynamics and the extra spatial degree of freedom in the ring ion scattering process with the help of two-dimensional full particle-in-cell (PIC) kinetic simulations. A good agreement is observed between ring evolution under unstable conditions in hybrid and PIC models, and the dominant modes are found to propagate parallel to the magnetic field. We also present more realistic ribbon PUI distributions generated using Monte Carlo simulations of atomic hydrogen in the global heliosphere and examine the effect of both the cold ring-like and the hot “halo” PUIs produced from heliosheath ENAs on the ring stability. It is shown that the second PUI population enhances the fluctuation growth rate, leading to faster isotropization of the solar-wind-derived ring ions.

  14. Lower hybrid drift instability in modified Harris current sheet with negative ions

    International Nuclear Information System (INIS)

    Huang Feng; Chen, Y-H; Shi Guifen; Hu, Z-Q; Yu, M Y

    2008-01-01

    The lower hybrid drift instability (LHDI) in a Harris current sheet with negative ions is investigated using the kinetic theory. Numerical results show that the negative ions have considerable effect on the LHDI. With increase of the negative-ion concentration, the growth rate of the LHDI increases and its real frequency decreases for any wave length. The Harris current sheet can thus be significantly modified

  15. Characteristics of a High Current Helicon Ion Source With High Monatomic Fraction

    International Nuclear Information System (INIS)

    Jung, Hwa-Dong; Chung, Kyoung-Jae; Hwang, Yong-Seok

    2006-01-01

    Applications of neutron need compact and high yield neutron sources as well as very intense neutron sources from giant devices such as accelerators. Ion source based neutron sources using nuclear fusion reactions such as D(d, 3He)n, D(t, 4He)n can meet the requirements. This type of neutron generators can be simply composed of an ion source and a target. High-performance neutron generators with high yield require ion sources with high beam current, high monatomic fraction and long lifetime. Helicon ion source can meet these requirements. To make high current ion source, characteristics of helicon plasma such as high plasma density can be utilized. Moreover, efficient plasma heating with RF power lead high fraction of monatomic ion beam. Here, Characteristics of helicon plasma sources are described. Design and its performances of a helicon ion source are presented

  16. Long-time dynamics of laser-cooled ions in the TSR storage ring

    International Nuclear Information System (INIS)

    Mudrich, M.

    2000-01-01

    This diploma thesis studies experimentally the long-time dynamics of laser-cooled 9 Be + -beams at the TSR under different cooling conditions. The goal is to enlarge the understanding of ultra-cold, non-neutral plasma at high center-of-mass energies. By means of improved measurement capabilities one can now for the first time monitor the entire phase-space over a long time. This makes it possible to quantitatively analyse the possibilities and limitations of laser cooling at a storage ring. Under optimum cooling conditions a regime of high phase-space density is reached, close to the region where influences of Coulomb coupling are expected. Furthermore, a Monte-Carlo model is worked out that qualitatively describes the beam dynamics. The model includes the influence of transverse-longitudinal coupling due to intra beam scattering on the longitudinal phase-space distribution. At high phase-space density a sudden disappearance of intra beam collisions is observed experimentally and possible interpretations are given. (orig.)

  17. Ring Current Ion Composition during Solar Minimum and Rising Solar Activity: POLAR/CAMMICE/MICS Results

    National Research Council Canada - National Science Library

    Pulkkinen, T

    2001-01-01

    ... observations from the WIND spacecraft during a period from September 1996 to March 1999. The statistics are performed both for time-averaged values for all periods as well as for peak flux values during geomagnetic storms (defined as Dst < -50 nT...

  18. High-current heavy-ion accelerator system and its application to material modification

    International Nuclear Information System (INIS)

    Kishimoto, Naoki; Takeda, Yoshihiko; Lee, C.G.; Umeda, Naoki; Okubo, Nariaki; Iwamoto, Eiji

    2001-01-01

    A high-current heavy-ion accelerator system has been developed to realize intense particle fluxes for material modification. The facility of a tandem accelerator attained 1 mA-class ion current both for negative low-energy ions and positive high-energy ions. The negative ion source of the key device is of the plasma-sputter type, equipped with mutli-cusp magnets and Cs supply. The intense negative ions are either directly used for material irradiation at 60 keV or further accelerated up to 6 MeV after charge transformation. Application of negative ions, which alleviates surface charging, enables us to conduct low-energy high-current irradiation on insulating substrates. Since positive ions above the MeV range are irrelevant for Coulomb repulsion, the facility as a whole meets the needs of high-current irradiation onto insulators over a wide energy range. Application of high flux ions provides technological merits not only for efficient implantation but also for essentially different material kinetics, which may become an important tool of material modification. Other advantages of the system are co-irradiation by intense laser and in-situ detection of kinetic processes. For examples of material modifications, we present nanoparticle fabrication in insulators, and synergistic phenomena by co-irradiation due to ions and photons. (author)

  19. Detection and clearing of trapped ions in the high current Cornell photoinjector

    Directory of Open Access Journals (Sweden)

    S. Full

    2016-03-01

    Full Text Available We have recently performed experiments to test the effectiveness of three ion-clearing strategies in the Cornell high intensity photoinjector: DC clearing electrodes, bunch gaps, and beam shaking. The photoinjector reaches a new regime of linac beam parameters where high continuous wave beam currents lead to ion trapping. Therefore ion mitigation strategies must be evaluated for this machine and other similar future high current linacs. We have developed several techniques to directly measure the residual trapped ions. Our two primary indicators of successful clearing are the amount of ion current removed by a DC clearing electrode, and the absence of bremsstrahlung radiation generated by beam-ion interactions. Measurements were taken for an electron beam with an energy of 5 MeV and continuous wave beam currents in the range of 1–20 mA. Several theoretical models have been developed to explain our data. Using them, we are able to estimate the clearing electrode voltage required for maximum ion clearing, the creation and clearing rates of the ions while employing bunch gaps, and the sinusoidal shaking frequency necessary for clearing via beam shaking. In all cases, we achieve a maximum ion clearing of at least 70% or higher, and in some cases our data is consistent with full ion clearing.

  20. Development of high-current pulsed heavy-ion-beam technology for applications to materials processing

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroaki; Ochiai, Yasushi; Masugata, Katsumi [University of Toyama, Toyama (Japan)

    2011-12-15

    Development of intense pulsed heavy ion beam technology for applications to materials processing is described. We have developed a magnetically insulated ion diode for the generation of intense pulsed metallic ion beams in which a vacuum arc plasma gun is used as the ion source. When the ion diode was successfully operated at a diode voltage of 220 kV and a diode current of 10 kA, an ion beam with an ion current density of >200 A/cm{sup 2} and a pulse duration of 40 ns was obtained. The ion composition was evaluated by using a Thomson parabola spectrometer, and the ion beam consisted of aluminum ions (Al{sup (1-3)+}) with an energy of 140 - 740 keV and protons with an energy of 160 - 190 keV; the purity was estimated to be 89%, which was much higher than that of the pulsed ion beam produced in a conventional ion diode. The development of a bipolar pulse accelerator (BPA) was reported in order to improve the purity of intense pulsed ion beams. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. When a bipolar pulse with a voltage of {+-}90 kV and a pulse duration of about 65 ns was applied to the drift tube of the BPA, the ion beam with an ion current density of 2 A/cm{sup 2} and a pulse duration of 30 ns was observed 25 mm downstream from the cathode surface, which suggested bipolar pulse acceleration.

  1. Performance evaluation of a permanent ring magnet based helicon plasma source for negative ion source research

    Science.gov (United States)

    Pandey, Arun; Bandyopadhyay, M.; Sudhir, Dass; Chakraborty, A.

    2017-10-01

    Helicon wave heated plasmas are much more efficient in terms of ionization per unit power consumed. A permanent magnet based compact helicon wave heated plasma source is developed in the Institute for Plasma Research, after carefully optimizing the geometry, the frequency of the RF power, and the magnetic field conditions. The HELicon Experiment for Negative ion-I source is the single driver helicon plasma source that is being studied for the development of a large sized, multi-driver negative hydrogen ion source. In this paper, the details about the single driver machine and the results from the characterization of the device are presented. A parametric study at different pressures and magnetic field values using a 13.56 MHz RF source has been carried out in argon plasma, as an initial step towards source characterization. A theoretical model is also presented for the particle and power balance in the plasma. The ambipolar diffusion process taking place in a magnetized helicon plasma is also discussed.

  2. Ion current prediction model considering columnar recombination in alpha radioactivity measurement using ionized air transportation

    International Nuclear Information System (INIS)

    Naito, Susumu; Hirata, Yosuke; Izumi, Mikio; Sano, Akira; Miyamoto, Yasuaki; Aoyama, Yoshio; Yamaguchi, Hiromi

    2007-01-01

    We present a reinforced ion current prediction model in alpha radioactivity measurement using ionized air transportation. Although our previous model explained the qualitative trend of the measured ion current values, the absolute values of the theoretical curves were about two times as large as the measured values. In order to accurately predict the measured values, we reinforced our model by considering columnar recombination and turbulent diffusion, which affects columnar recombination. Our new model explained the considerable ion loss in the early stage of ion diffusion and narrowed the gap between the theoretical and measured values. The model also predicted suppression of ion loss due to columnar recombination by spraying a high-speed air flow near a contaminated surface. This suppression was experimentally investigated and confirmed. In conclusion, we quantitatively clarified the theoretical relation between alpha radioactivity and ion current in laminar flow and turbulent pipe flow. (author)

  3. Fast-ion transport and neutral beam current drive in ASDEX upgrade

    DEFF Research Database (Denmark)

    Geiger, B.; Weiland, M.; Jacobsen, Asger Schou

    2015-01-01

    The neutral beam current drive efficiency has been investigated in the ASDEX Upgrade tokamak by replacing on-axis neutral beams with tangential off-axis beams. A clear modification of the radial fast-ion profiles is observed with a fast-ion D-alpha diagnostic that measures centrally peaked profiles...... during on-axis injection and outwards shifted profiles during off-axis injection. Due to this change of the fast-ion population, a clear modification of the plasma current profile is predicted but not observed by a motional Stark effect diagnostic. The fast-ion transport caused by MHD activity has been...

  4. Investigation of the isochronous mode of the experimental storage ring (ESR) and the collector ring (CR). Decay spectroscopy of highly charged stored 140Pr ions at the FRS-ESR facility

    International Nuclear Information System (INIS)

    Litvinov, Sergey A.

    2008-11-01

    The combination of the present fragment separator FRS and the cooler-storage ring ESR at GSI provides conditions for accurate mass and unique half-life measurements of exotic nuclei. A major part of this doctoral work has been devoted to investigations of the isochronous ion-optical operating mode of the present ESR facility and the planned Collector Ring (CR) facility at FAIR. A detailed ion-optical study of the isochronous storage ring with the emphasis on the main parameters has been done. For example, a simple scaling law providing a quantitative estimate for the mass resolving power as a function of the transverse acceptance has been derived. The ion-optical matching of the FRS-ESR has been calculated and experimentally verified for both the standard and the isochronous operating modes of the ESR. In addition, the dispersion function of a stored ion beam has been measured for both ion-optical modes at the straight section. The improved setting for higher transmission in the standard mode has been used in an experiment on the half-life measurements of highly-charged ions. Orbital electron capture (EC) and/or β + -decay rates of 140 Pr ions with zero-, one- and two- bound electrons have been measured. A complementary future study of EC-decay in highly-charged 64 Cu ions is discussed. Based on the present experience, the ion-optical matching between the future in-flight fragment separator Super-FRS and the CR has been calculated. The isochronous mode of the CR has been calculated. A dedicated Monte-Carlo code (ISOCHRON) has been developed in order to investigate the influence of the transverse acceptance, the closed orbit distortions, the fringe fields of the quadrupoles, the magnetic field imperfections of the magnets on the mass resolving power. The influence of chromaticity on the isochronicity has been investigated. The correction of the chromaticity and of second-order isochronicity has been performed employing sextupole magnets in the arcs of the CR. The

  5. Investigation of the isochronous mode of the experimental storage ring (ESR) and the collector ring (CR). Decay spectroscopy of highly charged stored {sup 140}Pr ions at the FRS-ESR facility

    Energy Technology Data Exchange (ETDEWEB)

    Litvinov, Sergey A.

    2008-11-15

    The combination of the present fragment separator FRS and the cooler-storage ring ESR at GSI provides conditions for accurate mass and unique half-life measurements of exotic nuclei. A major part of this doctoral work has been devoted to investigations of the isochronous ion-optical operating mode of the present ESR facility and the planned Collector Ring (CR) facility at FAIR. A detailed ion-optical study of the isochronous storage ring with the emphasis on the main parameters has been done. For example, a simple scaling law providing a quantitative estimate for the mass resolving power as a function of the transverse acceptance has been derived. The ion-optical matching of the FRS-ESR has been calculated and experimentally verified for both the standard and the isochronous operating modes of the ESR. In addition, the dispersion function of a stored ion beam has been measured for both ion-optical modes at the straight section. The improved setting for higher transmission in the standard mode has been used in an experiment on the half-life measurements of highly-charged ions. Orbital electron capture (EC) and/or {beta}{sup +}-decay rates of {sup 140}Pr ions with zero-, one- and two- bound electrons have been measured. A complementary future study of EC-decay in highly-charged {sup 64}Cu ions is discussed. Based on the present experience, the ion-optical matching between the future in-flight fragment separator Super-FRS and the CR has been calculated. The isochronous mode of the CR has been calculated. A dedicated Monte-Carlo code (ISOCHRON) has been developed in order to investigate the influence of the transverse acceptance, the closed orbit distortions, the fringe fields of the quadrupoles, the magnetic field imperfections of the magnets on the mass resolving power. The influence of chromaticity on the isochronicity has been investigated. The correction of the chromaticity and of second-order isochronicity has been performed employing sextupole magnets in the

  6. Ion production and bipolar fluxes in a high-current plasma-filled diode

    International Nuclear Information System (INIS)

    Ivanenkov, G.V.

    1982-01-01

    The model and the evolution of behaviour of binary layers (BL) in expanding plasma of high current plasma-filled diode are described. The model estimates ion current and the laws of plasma expansion at the stage of BL intensive growth. The density range (10 12 -10 15 cm -3 ) is determined in which diode impedance growth takes place in connection with BL appearance. The density of ion current at the outlet of diode is 10 A/cm 2

  7. Comment on 'Effects of Magnetic Field Gradient on Ion Beam Current in Cylindrical Hall Ion Source

    International Nuclear Information System (INIS)

    Raitses, Y.; Smirnov A.; Fisch, N.J.

    2008-01-01

    It is argued that the key difference of the cylindrical Hall thruster (CHT) as compared to the end-Hall ion source cannot be exclusively attributed to the magnetic field topology [Tang et al. J. Appl. Phys., 102, 123305 (2007)]. With a similar mirror-type topology, the CHT configuration provides the electric field with nearly equipotential magnetic field surfaces and a better suppression of the electron cross-field transport, as compared to both the end-Hall ion source and the cylindrical Hall ion source of Tang et al

  8. Electrode cooling for long pulse high current ion sources

    International Nuclear Information System (INIS)

    McKenzie-Wilson, R.B.

    1979-01-01

    The need for cooling of electrode surface in ion sources for neutral beam line applications is summarized. The properties of possible cooling fluids are discussed and the decision to use water as a cooling fluid of choice is explained. The influence of source geometry on the design of a cooling canal is examined and two possible designs are presented. The need for model testing and the results of the tests on a model cathode are also discussed. Some remarks are also made on a method of predicting burnout failure of a cooled electrode

  9. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 2. Time evolution of the distribution function

    Science.gov (United States)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Villalon, E.

    1995-11-01

    The evolution of the bounce-averaged ring current/radiation belt proton distribution is simulated during resonant interactions with ducted plasmaspheric hiss. The plasmaspheric hiss is assumed to be generated by ring current electrons and to be damped by the energetic protons. Thus energy is transferred between energetic electrons and protons using the plasmaspheric hiss as a mediary. The problem is not solved self-consistently. During the simulation period, interactions with ring current electrons (not represented in the model) are assumed to maintain the wave amplitudes in the presence of damping by the energetic protons, allowing the wave spectrum to be held fixed. Diffusion coefficients in pitch angle, cross pitch angle/energy, and energy were previously calculated by Kozyra et al. (1994) and are adopted for the present study. The simulation treats the energy range, E>=80 keV, within which the wave diffusion operates on a shorter timescale than other proton loss processes (i.e., Coulomb drag and charge exchange). These other loss processes are not included in the simulation. An interesting result of the simulation is that energy diffusion maximizes at moderate pitch angles near the edge of the atmospheric loss cone. Over the simulation period, diffusion in energy creates an order of magnitude enhancement in the bounce-averaged proton distribution function at moderate pitch angles. The loss cone is nearly empty because scattering of particles at small pitch angles is weak. The bounce-averaged flux distribution, mapped to ionospheric heights, results in elevated locally mirroring proton fluxes. OGO 5 observed order of magnitude enhancements in locally mirroring energetic protons at altitudes between 350 and 1300 km and invariant latitudes between 50° and 60° (Lundblad and Soraas, 1978). The proton distributions were highly anisotropic in pitch angle with nearly empty loss cones. The similarity between the observed distributions and those resulting from this

  10. Development of the High Current Ion Source for Neutral Beam Injection

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hun Ju; Kim, S. H.; Jang, D. H. [Jae Ju University, Jaeju (Korea, Republic of)

    1997-08-01

    The scope of the 1st year research is to design an 140keV deuterium ion source which has a beam current of 30-40A. According to the collected data, the model of an ion source for NBI of KSTAR was established. The negative ion source, which has good neutralization effecting in high energy, was selected. To generate a plasma, the thoriated tungsten filament was adopted. To increase the efficiency of plasma, the multi cusp type magnetic field was attached. The magnetic field was calculated by POISSON code. The extraction structure was designed with EGUN code, to extract the high quality ion beam. The design of a high current ion source for NBI was carried out. To develop the high current ion source with the high operational stability and the long lifetime, the parameters including an arc current, gas pressure and extraction voltage should be optimized. If designed ion source would be fabricated, its parameters could be optimized experimentally. Through the optimization of the ion source parameter, the core technology for NBI is established and the experiment of current drive in the fusion device can be performed. This technology also can be applied to the synthesis of new material and semiconductor industry. 18 refs., 11 tabs., 19 figs. (author)

  11. Non-Uniformity of Ion Implantation in Direct-Current Plasma Immersion Ion Implantation

    International Nuclear Information System (INIS)

    Cheng-Sen, Liu; Yu-Jia, Fan; Nan, Zhang; Li, Guan; Yuan, Yao; De-Zhen, Wang

    2010-01-01

    A particle-in-cell simulation is developed to study dc plasma immersion ion implantation. Particular attention is paid to the influence of the voltage applied to the target on the ion path, and the ion flux distribution on the target surface. It is found that the potential near the aperture within the plasma region is not the plasma potential, and is impacted by the voltage applied to the implanted target. A curved equipotential contour expands into the plasma region through the aperture and the extent of the expansion depends on the voltage. Ions accelerated by the electric field in the sheath form a beam shape and a flux distribution on the target surface, which are strongly dependent on the applied voltage. The results of the simulations demonstrate the formation mechanism of the grid-shadow effect, which is in agreement with the result observed experimentally. (physics of gases, plasmas, and electric discharges)

  12. Simulation of electron and ion bipolar flow in high current diode with magnetic insulation

    International Nuclear Information System (INIS)

    Vrba, P.; Engelko, V.I.

    1990-08-01

    Numerical simulation of the formation of the collector ion flow in a magnetically insulated ion diode (MID) with a hollow cylindrical and cone-shaped cathode was studied. Such cathodes are often used for the production of tubular high current microsecond electron beams. The ions, emitted by the collector and born as a result of ionization of the residual gas by the electron beam, are focused into the cathode plasma region. This effect can adversely influence the diode operation

  13. Maximizing ion current rectification in a bipolar conical nanopore fluidic diode using optimum junction location.

    Science.gov (United States)

    Singh, Kunwar Pal

    2016-10-12

    The ion current rectification has been obtained as a function of the location of a heterojunction in a bipolar conical nanopore fluidic diode for different parameters to determine the junction location for maximum ion current rectification using numerical simulations. Forward current peaks for a specific location of the junction and reverse current decreases with the junction location due to a change in ion enrichment/depletion in the pore. The optimum location of the heterojunction shifts towards the tip with base/tip diameter and surface charge density, and towards the base with the electrolyte concentration. The optimum location of the heterojunction has been approximated by an equation as a function of pore length, base/tip diameter, surface charge density and electrolyte concentration. The study is useful to design a rectifier with maximum ion current rectification for practical purposes.

  14. Plasma flow between equipotential electrodes in an ion current transport mode

    International Nuclear Information System (INIS)

    Zimin, A.M.; Morozov, A.I.

    1995-01-01

    The paper deals with calculation of parameters in accelerator channel and near electrodes, when realizing ion current transport mode. Model on the basis of two-dimensional two-liquid nondissipative magnetohydrodynamics was formulated, and its solution for isomagnetic flow in smooth channel approximation was conducted. Change of parameters near anode surface was considered in detail. It is shown that regular joining of flow with equipotential electrodes without large near-electrode jumps is performed during ion current transport. Current distribution along accelerator length was calculated when determining ion intake through anode surface due to inertial-drift emission. It is shown that this mechanism can provide rather high current density in ion current transport. 10 refs.; 6 figs

  15. Transport and acceleration of the high-current ion beam in magneto-isolated gap

    International Nuclear Information System (INIS)

    Karas', V.I.; Kornilov, E.A.; Manuilenko, O.V.; Fedorovskaya, O.V.; Tarakanov, V.P.

    2015-01-01

    The possibility of transportation and acceleration of the high-current ion beam in the magneto-isolated gap has been demonstrated. Found the parameters of the system and beams (the magnetic field produced by the coils with opposing currents, the size of the system, and the parameters of the beams), under which the uniform acceleration of the high-current ion beam all along the gap length is realized. It is shown that the quality of the ion beam, during transport and acceleration, at the exit of the gap is acceptable for many technological applications.

  16. Electron Currents and Heating in the Ion Diffusion Region of Asymmetric Reconnection

    Science.gov (United States)

    Graham, D. B.; Khotyaintsev, Yu. V.; Norgren, C.; Vaivads, A.; Andre, M.; Lindqvist, P. A.; Marklund, G. T.; Ergun, R. E.; Paterson, W. R.; Gershman, D. J.; hide

    2016-01-01

    In this letter the structure of the ion diffusion region of magnetic reconnection at Earths magnetopause is investigated using the Magnetospheric Multiscale (MMS) spacecraft. The ion diffusion region is characterized by a strong DC electric field, approximately equal to the Hall electric field, intense currents, and electron heating parallel to the background magnetic field. Current structures well below ion spatial scales are resolved, and the electron motion associated with lower hybrid drift waves is shown to contribute significantly to the total current density. The electron heating is shown to be consistent with large-scale parallel electric fields trapping and accelerating electrons, rather than wave-particle interactions. These results show that sub-ion scale processes occur in the ion diffusion region and are important for understanding electron heating and acceleration.

  17. Extended theory of main ion and impurity rotation and bootstrap current in a shear layer

    International Nuclear Information System (INIS)

    Kim, Y.B.; Hinton, F.L.; St. John, H.; Taylor, T.S.; Wroblewski, D.

    1993-11-01

    In this paper, standard neoclassical theory has been extended into the shear layer. Main ion and impurity ion rotation velocity and bootstrap current within shear layer in H-mode are discussed. Inside the H-mode shear layer, standard neoclassical theory is not valid since the ion poloidal gyroradius becomes comparable to pressure gradient and electric field gradient scale length. To allow for arbitrary ratio of ρθi/L n and ρθi/L Er a new kinetic theory of main ion species within electric field shear layer has been developed with the assumption that ρθi/R o is still small. As a consequence, both impurity flows and bootstrap current have to be modified. We present modified expressions of impurity flows and bootstrap current are presented neglecting ion temperature gradient. Comparisons with DIII-D measurements are also discussed

  18. Difference between ²JC2H3 and ²JC3H2 spin-spin couplings in heterocyclic five- and six-membered rings as a probe for studying σ-ring currents: a quantum chemical analysis.

    Science.gov (United States)

    Contreras, Rubén H; dos Santos, Francisco P; Ducati, Lucas C; Tormena, Cláudio F

    2010-12-01

    Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different σ-Fermi contact (FC) coupling pathways (FC term transmitted through the σ-skeleton). Knowledge of the spatial distribution of CMOs is obtained by expanding them in terms of natural bond orbitals (NBOs). Their relative importance for transmitting the σ-FC contribution to a given spin-spin coupling constants (SSCCs) is estimated by resorting to the expression of the FC term given by the polarisation propagator formalism. In this way, it is possible to classify the effects affecting such couplings in two different ways: delocalisation interactions taking place in the neighbourhood of the coupling nuclei and 'round the ring' effects. The latter, associated with σ-ring currents, are observed to yield significant differences between the FC terms of (2)J(C2H3) and (2)J(C3H2) SSCCs which, consequently, are taken as probes to gauge the differences in σ-ring currents for the five-membered rings (furan, thiophene, selenophene and pyrrol) and also for the six-membered rings (benzene, pyridine, protonated pyridine and N-oxide pyridine) used in the present study. Copyright © 2010 John Wiley & Sons, Ltd.

  19. Statistical mechanical characteristics of slip-ring induction motors when direct current braking

    Energy Technology Data Exchange (ETDEWEB)

    Kedzior, W; Muchorowski, J; Pienkowski, K

    1980-09-01

    This paper evaluates methods of braking high capacity belt conveyors used in brown coal surface mines in Poland. Complications associated with belt conveyor braking, particularly when a conveyor moves down a slope, are analyzed. A method of calculating mechanical characteristics of wound-rotor induction motors during direct current braking taking into account saturation of magnetic circuit is presented. Characteristics of the SZUr motor with 630 kW power, used in brown coal mining, are also given. Analyses show that motor operation can be efficiently braked in two ways: 1. by changing additional resistance in rotor circuit (e.g. using thyristor controller); 2. by changing intensity of electric current supplied to stator winding (e.g. using a rectifier). (3 refs.) (In Polish)

  20. Central plane of the ring current responsible for geomagnetic disturbance in the South-American region

    International Nuclear Information System (INIS)

    Kane, R.P.; Trivedi, N.B.

    1981-01-01

    Using hourly values of H, D, Z from a network of South American stations, operative during the IGY-IGC, the latitude dependence of storm effects was studied. It was found that whereas there were considerable distortions due to conductivity anomalies under the Andes, there was also evidence of latitudinal excursions of overhead current system, not only from storm to storm but even during the course of the same storm

  1. Study of transient current induced by heavy-ion microbeams in Si and GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Hirao, Toshio; Nashiyama, Isamu; Kamiya, Tomihiro; Suda, Tamotu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    Heavy-ion microbeams were applied to the study of mechanism of single event upset (SEU). Transient current induced in p{sup +}n junction diodes by strike of heavy ion microbeam were measured by using a high-speed digitizing sampling system. (author)

  2. Current limitation by an electric double layer in ion laser discharges

    International Nuclear Information System (INIS)

    Torven, S.

    1977-12-01

    A theory for current limitation in ion laser discharges is investigated. The basic mechanism considered is saturation of the positive ion flux at an electric double layer by the limited flux of neutral atoms. The result is compared with a recently published synthesis of a large number of experimental data which agree well with those predicted by the double layer model

  3. Development of long lifetime-high current plasma cathode ion source

    International Nuclear Information System (INIS)

    Yabe, Eiji; Takayama, Kazuo; Fukui, Ryota.

    1987-01-01

    A long lifetime ion source with plasma cathode has been developed for use in ion implantation. In this ion source, a plasma of a nonreactive working gas serves as a cathode in place of a thermionic tungsten filament used in the Freeman ion source. In an applied magnetic field, the plasma cathode is convergent, i.e. filament-like; in zero magnetic field, it turns divergent and spray-like. In the latter case, the plasma exhibits a remarkable ability when the working gas has an ionization potential larger than the feed gas. By any combination of a working gas of either argon or neon and a feed gas of AsF 5 or PF 5 , the lifetime of this ion source was found to be more than 90 hours with an extraction voltage of 40 kV and the corresponding ion current density 20 mA/cm 2 . Mass spectrometry results show that this ion source has an ability of generating a considerable amount of As + and P + ions from AsF 5 and PF 5 , and hence will be useful for realizing a fully cryopumped ion implanter system. This ion source is eminently suitable for use in oxygen ion production. (author)

  4. Independent control of ion current and ion impact energy onto electrodes in dual frequency plasma devices

    International Nuclear Information System (INIS)

    Boyle, P C; Ellingboe, A R; Turner, M M

    2004-01-01

    Dual frequency capacitive discharges are designed to offer independent control of the flux and energy of ions impacting on an object immersed in a plasma. This is desirable in applications such as the processing of silicon wafers for microelectronics manufacturing. In such discharges, a low frequency component couples predominantly to the ions, while a high frequency component couples predominantly to electrons. Thus, the low frequency component controls the ion energy, while the high frequency component controls the plasma density. Clearly, this desired behaviour is not achieved for arbitrary configurations of the discharge, and in general one expects some unwanted coupling of ion flux and energy. In this paper we use computer simulations with the particle-in-cell method to show that the most important governing parameter is the ratio of the driving frequencies. If the ratio of the high and low frequencies is great enough, essentially independent control of the ion energy and flux is possible by manipulation of the high and low frequency power sources. Other operating parameters, such as pressure, discharge geometry, and absolute power, are of much less significance

  5. Magnetically filtered Faraday probe for measuring the ion current density profile of a Hall thruster

    International Nuclear Information System (INIS)

    Rovey, Joshua L.; Walker, Mitchell L.R.; Gallimore, Alec D.; Peterson, Peter Y.

    2006-01-01

    The ability of a magnetically filtered Faraday probe (MFFP) to obtain the ion current density profile of a Hall thruster is investigated. The MFFP is designed to eliminate the collection of low-energy, charge-exchange (CEX) ions by using a variable magnetic field as an ion filter. In this study, a MFFP, Faraday probe with a reduced acceptance angle (BFP), and nude Faraday probe are used to measure the ion current density profile of a 5 kW Hall thruster operating over the range of 300-500 V and 5-10 mg/s. The probes are evaluated on a xenon propellant Hall thruster in the University of Michigan Large Vacuum Test Facility at operating pressures within the range of 4.4x10 -4 Pa Xe (3.3x10 -6 Torr Xe) to 1.1x10 -3 Pa Xe (8.4x10 -6 Torr Xe) in order to study the ability of the Faraday probe designs to filter out CEX ions. Detailed examination of the results shows that the nude probe measures a greater ion current density profile than both the MFFP and BFP over the range of angular positions investigated for each operating condition. The differences between the current density profiles obtained by each probe are attributed to the ion filtering systems employed. Analysis of the results shows that the MFFP, operating at a +5 A solenoid current, provides the best agreement with flight-test data and across operating pressures

  6. Nonadiabatic generation of spin currents in a quantum ring with Rashba and Dresselhaus spin-orbit interactions

    International Nuclear Information System (INIS)

    Niţa, Marian; Ostahie, Bogdan; Marinescu, D C; Manolescu, Andrei; Gudmundsson, Vidar

    2012-01-01

    When subjected to a linearly polarized terahertz pulse, a mesoscopic ring endowed with spin-orbit interaction (SOI) of the Rashba-Dresselhaus type exhibits non-uniform azimuthal charge and spin distributions. Both types of SOI couplings are considered linear in the electron momentum. Our results are obtained within a formalism based on the equation of motion satisfied by the density operator which is solved numerically for different values of the angle φ, the angle determining the polarization direction of the laser pulse. Solutions thus obtained are later employed in determining the time-dependent charge and spin currents, whose values are calculated in the stationary limit. Both these currents exhibit an oscillatory behavior complicated in the case of the spin current by a beating pattern. We explain this occurrence on account of the two spin-orbit interactions which force the electron spin to oscillate between the two spin quantization axes corresponding to Rashba and Dresselhaus interactions. The oscillation frequencies are explained using the single particle spectrum.

  7. Beam size blow-up and current loss in the Fermilab Main Ring during storage

    International Nuclear Information System (INIS)

    Guignard, C.; Month, M.

    1977-01-01

    Observations at Fermilab during storage mode operation show characteristic forms of transverse beam size growth and current loss with time. There are three obvious mechanisms which can produce such blowup. The gas pressure is a source for immediate beam loss by direct nuclear scattering. Protons can also multiple scatter off the orbiting electrons of the gas atoms causing the trasnverse beam size to increase with time. A third mechanism not related to gas pressure is beam growth due to multiple crossing of betatron resonances arising from the synchrotron oscillations of the stored bunches. This simulates a random walk and causes the transverse beam size to grow. This is an attempt to describe the observations with direct nuclear scattering, multiple coulomb scattering, and multiple resonance crossing

  8. Ladder-Shaped Ion Channel Ligands: Current State of Knowledge

    Science.gov (United States)

    Shmukler, Yuri B.; Nikishin, Denis A.

    2017-01-01

    Ciguatoxins (CTX) and brevetoxins (BTX) are polycyclic ethereal compounds biosynthesized by the worldwide distributed planktonic and epibenthic dinoflagellates of Gambierdiscus and Karenia genera, correspondingly. Ciguatera, evoked by CTXs, is a type of ichthyosarcotoxism, which involves a variety of gastrointestinal and neurological symptoms, while BTXs cause so-called neurotoxic shellfish poisoning. Both types of toxins are reviewed together because of similar mechanisms of their action. These are the only molecules known to activate voltage-sensitive Na+-channels in mammals through a specific interaction with site 5 of its α-subunit and may compete for it, which results in an increase in neuronal excitability, neurotransmitter release and impairment of synaptic vesicle recycling. Most marine ciguatoxins potentiate Nav channels, but a considerable number of them, such as gambierol and maitotoxin, have been shown to affect another ion channel. Although the extrinsic function of these toxins is probably associated with the function of a feeding deterrent, it was suggested that their intrinsic function is coupled with the regulation of photosynthesis via light-harvesting complex II and thioredoxin. Antagonistic effects of BTXs and brevenal may provide evidence of their participation as positive and negative regulators of this mechanism. PMID:28726749

  9. Ladder-Shaped Ion Channel Ligands: Current State of Knowledge

    Directory of Open Access Journals (Sweden)

    Yuri B. Shmukler

    2017-07-01

    Full Text Available Ciguatoxins (CTX and brevetoxins (BTX are polycyclic ethereal compounds biosynthesized by the worldwide distributed planktonic and epibenthic dinoflagellates of Gambierdiscus and Karenia genera, correspondingly. Ciguatera, evoked by CTXs, is a type of ichthyosarcotoxism, which involves a variety of gastrointestinal and neurological symptoms, while BTXs cause so-called neurotoxic shellfish poisoning. Both types of toxins are reviewed together because of similar mechanisms of their action. These are the only molecules known to activate voltage-sensitive Na+-channels in mammals through a specific interaction with site 5 of its α-subunit and may compete for it, which results in an increase in neuronal excitability, neurotransmitter release and impairment of synaptic vesicle recycling. Most marine ciguatoxins potentiate Nav channels, but a considerable number of them, such as gambierol and maitotoxin, have been shown to affect another ion channel. Although the extrinsic function of these toxins is probably associated with the function of a feeding deterrent, it was suggested that their intrinsic function is coupled with the regulation of photosynthesis via light-harvesting complex II and thioredoxin. Antagonistic effects of BTXs and brevenal may provide evidence of their participation as positive and negative regulators of this mechanism.

  10. Novel Faraday cup for the simultaneous observation and measurement of ion-beam currents

    International Nuclear Information System (INIS)

    Wei, C.Y.; Seidman, D.N.

    1977-07-01

    The Faraday cup is constructed around a Galileo channel electron multiplier array (CEMA) which serves as the basis of an internal image intensification system (a gain of greater than 10 4 ) for the observation of the ion beam; the CEMA also acts as a collector for the ion cured by a Keithley 602 electrometer. The ion current is integrated by a simple and inexpensive dosimeter; the electronic circuit for the dosimeter is described. The application of the Faraday cup to the observation and measurement of a 30 keV Ar + ion beam is presented as an illustrative example. This Faraday cup was also employed to observe and measure 30 keV Cr + , Mo + or W + and 18 keV Au + ion beams employed for the in-situ irradiation of field-ion microscope specimens

  11. Bremsstrahlung and Ion Beam Current Measurements with SuSI ECR Ion Source

    International Nuclear Information System (INIS)

    Ropponen, T.

    2012-01-01

    This series of slides presents: the Superconducting Source for Ions (SuSI), the X-ray measurement setup, the different collimation schemes, the flat B operation versus B(min) operation, and the impact of tuning ∇B while keeping fixed field profile

  12. Design considerations for high-current superconducting ion linacs

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.; Micklich, B.J.; Roche, C.T.; Sagalovsky, L.

    1993-01-01

    Superconducting linacs may be a viable option for high-current applications such as fusion materials irradiation testing, spallation neutron source, transmutation of radioactive waste, tritium production, and energy production. These linacs must run reliably for many years and allow easy routine maintenance. Superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs, respectively. However, cost-effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement. Key aspects of high-current cw superconducting linac designs are explored in this context

  13. Dependence of secondary ion emission current on the composition of beryllium-nickel alloys

    International Nuclear Information System (INIS)

    Pistryak, V.M.; Kozlov, V.F.; Tikhinskij, G.F.; Fogel', Ya.M.

    1976-01-01

    The dependence is studied of the secondary ions emission current on the composition of beryllium-nickel alloys. It is established that appearance of intermetallide phases in the Be-Ni alloys has no effect on the linear character of the secondary ions Ni + and Be + of emission current. The phase transformation from the solid solution to the compound Ni 5 Be 21 with a change in the alloys concentration is fixed by appearance of the secondary ion NiBe + emission. The limited solubility of nickel in solid beryllium at a temperature close to room temperature is determined to be equal to 1.3+-0.27 at%

  14. Role of the lifetime of ring current particles on the solar wind-magnetosphere power transfer during the intense geomagnetic storm of 28 August 1978

    International Nuclear Information System (INIS)

    Gonzalez, W.D.; Gonzalez, A.L.C.; Lee, L.C.

    1990-01-01

    For the intense magnetic storms of 28 August 1978 it is shown that the power transfer from the solar wind to the magnetosphere is well represented by the expression obtained by Vasyliunas et al. (1982, Planet. Space Sci. 30, 359) from dimensional analysis, but this representation becomes improved when such an expression is modified by a factor due to an influence of the lifetime of ring current particles as suggested by Lee and Akasofu (1984, Planet. Space Sci. 32, 1423). During a steady state regime of the ring current evolution of this storm, our study suggests that the power transfer depends on the solar wind density, the transverse component of the IMF (Interplanetary magnetic field) (with respect to the Sun-Earth line) and also, explicitly, on the time constant for ring current energy decay, but not on the solar wind speed. (author)

  15. Beam size blow-up and current loss in the Fermilab main ring during storage

    International Nuclear Information System (INIS)

    Guignard, G.; Month, M.

    1977-01-01

    Observations at Fermilab during the storage mode of operation show characteristic forms of transverse beam size growth and current loss with time. There are three obvious mechanisms which can produce such blowup. The gas pressure is a source for immediate beam loss by direct nuclear scattering. Protons can also multiple Coulomb scatter off the orbiting electrons of the gas atoms causing the transverse beam size to increase with time, t. This effect is therefore also proportional to the gas pressure. A third mechanism not related to the gas pressure is beam growth due to multiple crossing of betatron resonances arising from the synchrotron oscillations of the stored bunches. This simulates a random walk and causes the transverse beam size to grow with √t. An attempt is made to describe the observations with direct nuclear scattering, multiple coulomb scattering and multiple resonance crossing. In addition to the loss rate from direct nuclear scattering, the presence of betatron resonances also contribute to particle loss. In fact this latter effect becomes dominant after the beam size reaches a critical value. This critical size is referred to as the resonance aperture. It is the size at which ''fast'' resonance crossing is no longer valid. The stopband width becomes so large (due both to emittance growth as well as the increase in magnetic field distortions) that particles are locked into the resonance and are extracted to the physical aperture. The model is described in a phenomenological way, and the coefficients involved are estimated. Theoretical curves for transverse beam growth and loss rate are plotted and compared with some measured values. Finally, some general comments are given

  16. Calculation of ion currents across the inner membrane of functionally intact mitochondria

    Science.gov (United States)

    Kane, Daniel A; Pavlov, Evgeny V

    2013-01-01

    Mitochondrial ion transport systems play a central role in cell physiology. Rates of Ca2+ and K+ transport across the inner mitochondrial membrane have been derived from the measurement of ion accumulation over time within functional isolated mitochondria or mitochondria of cultured cells. Alternatively, the electrical currents generated by ionic flux have been directly measured in purified and swollen mitochondrial samples (mitoplasts) or reconstituted channels, and typically range from 1 pA to several 100s pA. However, the direct electrophysiological approach necessarily requires extensive processing of the mitochondria prior to measurement, which can only be performed on isolated mitoplasts. To compare rates of mitochondrial ion transport measured in electrophysiological experiments to those measured in intact mitochondria and cells, we converted published rates of mitochondrial ion uptake into units of ionic current. We estimate that for monovalent ions, uptake by intact mitochondria at the rate of 1 nmol ∙ mg−1 protein ∙ min−1 is equivalent to 0.2 fA of current per whole single mitochondrion (0.4 fA for divalent ions). In intact mitochondria, estimated rates of electrogenic cation uptake are limited to 1–100 fA of integral current per single mitochondrion. These estimates are orders of magnitude lower than the currents through mitochondrial channels directly measured via patch-clamp or artificial lipid bilayer approaches. PMID:24037064

  17. Leakage current of amorphous silicon p-i-n diodes made by ion shower doping

    International Nuclear Information System (INIS)

    Kim, Hee Joon; Cho, Gyuseong; Choi, Joonhoo; Jung, Kwan-Wook

    2002-01-01

    In this letter, we report the leakage current of amorphous silicon (a-Si:H) p-i-n photodiodes, of which the p layer is formed by ion shower doping. The ion shower doping technique has an advantage over plasma-enhanced chemical vapor deposition (PECVD) in the fabrication of a large-area amorphous silicon flat-panel detector. The leakage current of the ion shower diodes shows a better uniformity within a 30 cmx40 cm substrate than that of the PECVD diodes. However, it shows a higher leakage current of 2-3 pA/mm 2 at -5 V. This high current originates from the high injection current at the p-i junction

  18. Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

    International Nuclear Information System (INIS)

    Kaganovich, Igor D.; Shvets, Gennady; Startsev, Edward; Davidson, Ronald C.

    2001-01-01

    The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma

  19. Determination of plasma density from data on the ion current to cylindrical and planar probes

    Energy Technology Data Exchange (ETDEWEB)

    Voloshin, D. G., E-mail: dvoloshin@mics.msu.su; Vasil’eva, A. N.; Kovalev, A. S.; Mankelevich, Yu. A.; Rakhimova, T. V. [Moscow State University, Skobeltsyn Nuclear Physics Institute (Russian Federation)

    2016-12-15

    To improve probe methods of plasma diagnostics, special probe measurements were performed and numerical models describing ion transport to a probe with allowance for collisions were developed. The current–voltage characteristics of cylindrical and planar probes were measured in an RF capacitive discharge in argon at a frequency of 81 MHz and plasma densities of 10{sup 10}–10{sup 11} cm{sup –3}, typical of modern RF reactors. 1D and 2D numerical models based on the particle-in-cell method with Monte Carlo collisions for simulating ion motion and the Boltzmann equilibrium for electrons are developed to describe current collection by a probe. The models were used to find the plasma density from the ion part of the current–voltage characteristic, study the effect of ion collisions, and verify simplified approaches to determining the plasma density. A 1D hydrodynamic model of the ion current to a cylindrical probe with allowance for ion collisions is proposed. For a planar probe, a method to determine the plasma density from the averaged numerical results is developed. A comparative analysis of different approaches to calculating the plasma density from the ion current to a probe is performed.

  20. Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Igor D. Kaganovich; Gennady Shvets; Edward Startsev; Ronald C. Davidson

    2001-01-30

    The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma.

  1. Inverted end-Hall-type low-energy high-current gaseous ion source

    International Nuclear Information System (INIS)

    Oks, E. M.; Vizir, A. V.; Shandrikov, M. V.; Yushkov, G. Yu.; Grishin, D. M.; Anders, A.; Baldwin, D. A.

    2008-01-01

    A novel approach to low-energy, high-current, gaseous ion beam generation was explored and an ion source based on this technique has been developed. The source utilizes a dc high-current (up to 20 A) gaseous discharge with electron injection into the region of ion generation. Compared to the conventional end-Hall ion source, the locations of the discharge anode and cathode are inverted: the cathode is placed inside the source and the anode outside, and correspondingly, the discharge current is in the opposite direction. The discharge operates in a diverging axial magnetic field, similar to the end-Hall source. Electron generation and injection is accomplished by using an additional arc discharge with a ''cold'' (filamentless) hollow cathode. Low plasma contamination is achieved by using a low discharge voltage (avoidance of sputtering), as well as by a special geometric configuration of the emitter discharge electrodes, thereby filtering (removing) the erosion products stemming from the emitter cathode. The device produces a dc ion flow with energy below 20 eV and current up to 2.5 A onto a collector of 500 cm 2 at 25 cm from the source edge, at a pressure ≥0.02 Pa and gas flow rate ≥14 SCCM. The ion energy spread is 2 to 3 eV (rms). The source is characterized by high reliability, low maintenance, and long lifetime. The beam contains less than 0.1% of metallic ions. The specific electric energy consumption is 400 eV per ion registered at the collector. The source operates with noble gases, nitrogen, oxygen, and hydrocarbons. Utilizing biasing, it can be used for plasma sputtering, etching, and other ion technologies

  2. Measurement of the ratio of C3+ and O4+ ions produced by ECRIS to prepare a laser cooling experiment at storage rings

    International Nuclear Information System (INIS)

    Zhu, X.L.; Wen, W.Q.; Ma, X.; Li, J.Y.; Feng, W.T.; Zhang, R.T.; Wang, Enliang; Yan, S.; Guo, D.L.; Hai, B.; Qian, D.B.; Zhang, P.; Xu, S.; Zhao, D.M.; Yang, J.; Zhang, D.C.; Li, B.; Gao, Y.; Huang, Z.K.; Wang, H.B.

    2014-01-01

    To prepare the upcoming laser cooling of relativistic C 3+ ion beams at the experimental Cooler Storage Ring (CSRe), a novel experiment was performed using a reaction microscope to determine the ratio of C 3+ ions in mixed ion beams of C 3+ and O 4+ that are produced by an Electron Cyclotron Resonance Ion Source (ECRIS). The mixed ion beams at an energy of 4 keV/u were directed to collide on a supersonic helium gas target. Using the single-electron capture channel and the coincidence technique, the fractions of C 3+ and O 4+ ions in the primary beam were obtained. Using different injection gases for ECRIS, including O 2 , CO, CO 2 , and CH 4 , at a fixed radio-frequency power of 300 W, the measured results showed that the fraction of C 3+ ions was greater than 70% for the injection gases of CO and CO 2 . These measured results are very important and helpful for the upcoming laser cooling experiments

  3. Fabrication And Characterization of YBa2Cu3O7-x Ring For The Laboratory Scale Fault Current Limiter

    International Nuclear Information System (INIS)

    Adi, Wisnu Ari; Sukirman, Engkir; Winatapura, Didin S.; Handayani, Ari

    2004-01-01

    Two rings of YBa 2 Cu 3 O 7-x superconductor have been made by using the pressing method, that has been modified. The inner diameter, outer diameter, and thickness of ring 1 are 23.46 mm, 40.66 mm, and 6.84 mm, while for ring 2 are 23.65 mm, 40.73 mm, and 8.28 mm, respectively. The XRD data show that both samples have the same 123-phase. The critical temperature, Tc of both samples is 91 K. The estimate values of induction magnetic field at the center of ring 1 and ring 2 are 1.27 x 10 -4 T (I c = 3.48 A) and 1.65 x 10 -4 T (I c = 3.52 A), respectively

  4. Leakage Current Degradation Due to Ion Drift and Diffusion in Tantalum and Niobium Oxide Capacitors

    Directory of Open Access Journals (Sweden)

    Kuparowitz Martin

    2017-06-01

    Full Text Available High temperature and high electric field applications in tantalum and niobium capacitors are limited by the mechanism of ion migration and field crystallization in a tantalum or niobium pentoxide insulating layer. The study of leakage current (DCL variation in time as a result of increasing temperature and electric field might provide information about the physical mechanism of degradation. The experiments were performed on tantalum and niobium oxide capacitors at temperatures of about 125°C and applied voltages ranging up to rated voltages of 35 V and 16 V for tantalum and niobium oxide capacitors, respectively. Homogeneous distribution of oxygen vacancies acting as positive ions within the pentoxide layer was assumed before the experiments. DCL vs. time characteristics at a fixed temperature have several phases. At the beginning of ageing the DCL increases exponentially with time. In this period ions in the insulating layer are being moved in the electric field by drift only. Due to that the concentration of ions near the cathode increases producing a positively charged region near the cathode. The electric field near the cathode increases and the potential barrier between the cathode and insulating layer decreases which results in increasing DCL. However, redistribution of positive ions in the insulator layer leads to creation of a ion concentration gradient which results in a gradual increase of the ion diffusion current in the direction opposite to the ion drift current component. The equilibrium between the two for a given temperature and electric field results in saturation of the leakage current value. DCL vs. time characteristics are described by the exponential stretched law. We found that during the initial part of ageing an exponent n = 1 applies. That corresponds to the ion drift motion only. After long-time application of the electric field at a high temperature the DCL vs. time characteristics are described by the exponential

  5. Production of ultrahigh ion current densities at skin-layer subrelativistic laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Badziak, J [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Glowacz, S [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Jablonski, S [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Parys, P [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Wolowski, J [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Hora, H [Department of Theoretical Physics, University of New South Wales, Sydney (Australia); Krasa, J [Institute of Physics, ASCR, Prague (Czech Republic); Laska, L [Institute of Physics, ASCR, Prague (Czech Republic); Rohlena, K [Institute of Physics, ASCR, Prague (Czech Republic)

    2004-12-01

    Some applications of fast ions driven by a short ({<=}1 ps) laser pulse (e.g. fast ignition of ICF targets, x-ray laser pumping, laboratory astrophysics research or some nuclear physics experiments) require ion beams of picosecond (or shorter) time durations and of very high ion current densities ({approx}10{sup 10} A cm{sup -2} or higher). A possible way of producing ion beams with such extreme parameters is ballistic focusing of fast ions generated by a target normal sheath acceleration (TNSA) mechanism at relativistic laser intensities. In this paper we discuss another method, where the production of short-pulse ion beams of ultrahigh current densities is possible in a planar geometry at subrelativistic laser intensities and at a low energy ({<=}1 J) of the laser pulse. This method-referred to as skin-layer ponderomotive acceleration (S-LPA)-uses strong ponderomotive forces induced at the skin-layer interaction of a short laser pulse with a proper preplasma layer in front of a solid target. The basic features of the high-current ion generation by S-LPA were investigated using a simplified theory, numerical hydrodynamic simulations and measurements. The experiments were performed with subjoule 1 ps laser pulses interacting with massive or thin foil targets at intensities of up to 2 x 10{sup 17} W cm{sup -2}. It was found that both in the backward and forward directions highly collimated high-density ion beams (plasma blocks) with current densities at the ion source (close to the target) approaching 10{sup 10} A cm{sup -2} are produced, in accordance with the theory and numerical calculations. These ion current densities were found to be comparable to (or even higher than) those estimated from recent short-pulse TNSA experiments with relativistic laser intensities. Apart from the simpler physics of the laser-plasma interaction, the advantage of the considered method is the low energy of the driving laser pulses allowing the production of ultrahigh-current

  6. Preliminary results of proton ring current observations in time of magnetic perturbations with the 'Molniya-1' satellite

    International Nuclear Information System (INIS)

    Grechin, A.N.; Kovrygina, L.M.; Kovtyukh, A.S.

    1975-01-01

    The experimental results of observation on the injection of the annular current protons (30< Esub(r)<380 KeV) into the radiation band during the storm on October 28, 1973 and three storms on January 1, 1974, July 12 and 21, 1974, with the maximum values of Dsup(st) of 65, 30, and 20γ, respectively, are described. During the main phases of the storms the assymetry of the annular current of protons relative to the mid-day-mid-night meridian was observed. The injection of the particles was being accompanied by variation of the shape of the spectrum on the internal edge of the annular current. The possible effect of the ion-cyclotron instability on the formation of the initial edge of the annular current has been analyzed. Immediately after the main phases of the storms on July 12 and 21, 1974, a gap in the spectum within the pre-mid-night sector, with the energies amounting to several dozens of KeV was observed. The formation of this gap may be explained by the development of the instability which results in the pinch-angular diffusion of protons and their decay in the region of plasmapause

  7. Ring Theory

    CERN Document Server

    Jara, Pascual; Torrecillas, Blas

    1988-01-01

    The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

  8. Experimental investigation of the ion current distribution in microsecond plasma opening switch

    Energy Technology Data Exchange (ETDEWEB)

    Bystritskij, V; Grigor` ev, S; Kharlov, A; Sinebryukhov, A [Russian Academy of Sciences, Tomsk (Russian Federation). Institute of Electrophysics

    1997-12-31

    This paper is devoted to the investigations of properties of the microsecond plasma opening switch (MPOS) as an ion beam source for surface modification. Two plasma sources were investigated: flash-board and cable guns. The detailed measurements of axial and azimuthal distributions of ion current density in the switch were performed. It was found that the azimuthal inhomogeneity of the ion beam increases from the beginning to the end of MPOS. The advantages and problems of this approach are discussed. (author). 5 figs., 2 refs.

  9. Heavy Ion Microbeam- and Broadbeam-Induced Current Transients in SiGe HBTs

    Science.gov (United States)

    Pellish, Jonathan A.; Reed, R. A.; McMorrow, D.; Vizkelethy, G.; Ferlet-Cavrois, V.; Baggio, J.; Duhamel, O.; Moen, K. A.; Phillips, S. D.; Diestelhorst, R. M.; hide

    2009-01-01

    IBM 5AM SiGe HBT is device-under-test. High-speed measurement setup. Low-impedance current transient measurements. SNL, JYFL, GANIL. Microbeam to broadbeam position inference. Improvement to state-of-the-art. Microbeam (SNL) transients reveal position dependent heavy ion response, Unique response for different device regions Unique response for different bias schemes. Similarities to TPA pulsed-laser data. Broadbeam transients (JYFL and GANIL) provide realistic heavy ion response. Feedback using microbeam data. Overcome issues of LET and ion range with microbeam. **Angled Ar-40 data in full paper. Data sets yield first-order results, suitable for TCAD calibration feedback.

  10. Topological rings

    CERN Document Server

    Warner, S

    1993-01-01

    This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

  11. Soft Wall Ion Channel in Continuum Representation with Application to Modeling Ion Currents in α-Hemolysin

    Science.gov (United States)

    Simakov, Nikolay A.

    2010-01-01

    A soft repulsion (SR) model of short range interactions between mobile ions and protein atoms is introduced in the framework of continuum representation of the protein and solvent. The Poisson-Nernst-Plank (PNP) theory of ion transport through biological channels is modified to incorporate this soft wall protein model. Two sets of SR parameters are introduced: the first is parameterized for all essential amino acid residues using all atom molecular dynamic simulations; the second is a truncated Lennard – Jones potential. We have further designed an energy based algorithm for the determination of the ion accessible volume, which is appropriate for a particular system discretization. The effects of these models of short-range interaction were tested by computing current-voltage characteristics of the α-hemolysin channel. The introduced SR potentials significantly improve prediction of channel selectivity. In addition, we studied the effect of choice of some space-dependent diffusion coefficient distributions on the predicted current-voltage properties. We conclude that the diffusion coefficient distributions largely affect total currents and have little effect on rectifications, selectivity or reversal potential. The PNP-SR algorithm is implemented in a new efficient parallel Poisson, Poisson-Boltzman and PNP equation solver, also incorporated in a graphical molecular modeling package HARLEM. PMID:21028776

  12. Calculating tracer currents through narrow ion channels: Beyond the independent particle model.

    Science.gov (United States)

    Coalson, Rob D; Jasnow, David

    2018-06-01

    Discrete state models of single-file ion permeation through a narrow ion channel pore are employed to analyze the ratio of forward to backward tracer current. Conditions under which the well-known Ussing formula for this ratio hold are explored in systems where ions do not move independently through the channel. Building detailed balance into the rate constants for the model in such a way that under equilibrium conditions (equal rate of forward vs. backward permeation events) the Nernst Equation is satisfied, it is found that in a model where only one ion can occupy the channel at a time, the Ussing formula is always obeyed for any number of binding sites, reservoir concentrations of the ions and electric potential difference across the membrane which the ion channel spans, independent of the internal details of the permeation pathway. However, numerical analysis demonstrates that when multiple ions can occupy the channel at once, the nonequilibrium forward/backward tracer flux ratio deviates from the prediction of the Ussing model. Assuming an appropriate effective potential experienced by ions in the channel, we provide explicit formulae for the rate constants in these models. © 2018 IOP Publishing Ltd.

  13. Theory of the current-driven ion cyclotron instability in the bottomside ionosphere

    International Nuclear Information System (INIS)

    Satyanarayana, P.; Chaturvedi, P.K.; Keskinen, M.J.; Huba, J.D.; Ossakow, S.L.

    1985-01-01

    A theory of the current-driven electrostatic ion cyclotron (EIC) instability in the collisional bottomside ionosphere is presented. It is found that electron collisions are destabilizing and are crucial for the excitation of the EIC instability in the collisional bottomside ionosphere. Furthermore, the growth rates of the ion cyclotron instability in the bottomside ionosphere maximize for k/sub perpendicular/ rho/sub i/> or =1, where 2π/k/sub perpendicular/ is the mode scale size perpendicular to the magnetic field and rho/sub i/ the ion gyroradius. Realistic plasma density and temperature profiles typical of the high-latitude ionosphere are used to compute the altitude dependence of the linear growth rate of the maximally growing modes and critical drift velocity of the EIC instability. The maximally growing modes correspond to observed tens of meter size irregularities, and the threshold drift velocity required for the excitation of EIC instability is lower for heavier ions (NO + , O + ) than that for the lighter ions (H + ). Dupree's resonance-broadening theory is used to estimate nonlinear saturated amplitudes for the ion cyclotron instability in the high-latitude ionosphere. Comparison with experimental observations is also made. It is conjectured that the EIC instability in the bottomside ionosphere could be a source of transversely accelerated heavier ions and energetic heavy-ion conic distributions at higher altitudes

  14. Simultaneous measurements of ion and electron currents using a novel compact electrostatic end-loss-current detector

    Science.gov (United States)

    Hirata, M.; Miyake, Y.; Cho, T.; Kohagura, J.; Numakura, T.; Shimizu, K.; Ito, M.; Kiminami, S.; Morimoto, N.; Hirai, K.; Yamagishi, T.; Miyata, Y.; Nakashima, Y.; Miyoshi, S.; Ogura, K.; Kondoh, T.; Kariya, T.

    2006-10-01

    For the purpose of end-loss-ion and -electron analyses in open-field plasmas, a compact-sized electrostatic end-loss-current detector is proposed on the basis of a self-collection principle for suppressing the effects of secondary-electron emission from a metal collector. For employing this specific method, it is worth noting that no further additional magnetic systems except the ambient open-ended magnetic fields are required in the detector operation. This characteristic property provides a compactness of the total detection system and availability for its use in plasma confinement devices without disturbing plasma-confining magnetic fields. The detector consists of a set of parallel metal plates with respect to lines of ambient magnetic forces of a plasma device for analyzing incident ion currents along with a grid for shielding the collector against strays due to the metal-plate biasing. The characterization experiments are carried out by the use of a test-ion-beam line along with an additional use of a Helmholtz coil system for the formation of open magnetic fields similar to those in the GAMMA 10 end region. The applications of the developed end-loss-current detector in the GAMMA 10 plasma experiments are demonstrated under the conditions with simultaneous incidence of energetic electrons produced by electron-cyclotron heatings for end-loss-plugging potential formation.

  15. Computer programmes for high current ion trajectories in a magnetic sector-type mass separator

    International Nuclear Information System (INIS)

    Nakai, Akira

    1988-01-01

    According to theoretical calculations previously proposed by the author, a new programme 'MALT' for electronic computers has been developed for numerical calculations of ion trajectories of a high current ion beam traversing a magnetic sector-type mass separator. In the programme, both effects of the fringing field and the space charge are taken into account in an analytical way, so that numerical calculations can be done straightforwardly. Furthermore, it becomes also possible to analyze and cotrol the trajectories of the high current ion beam. The programme MALT contains several subroutine programmes which are separated individually for the convenience of various calculations with respect to the high current ion beam. To demonstrate the calculations by the use of these subroutine programmes, a main programme for the calculation of the trajectories in the whole region of the separator is shown, which also makes it possible to draw the traces of the trajectories. The trajectories calculated by the proposed programme have been compared with the images of the ion beams recorded on novel dry plates developed by the author: the comparison enables us to evaluate the effective space charge and the effective space charge potential, and to analyze the behaviour of the beam of neutral particles accompanying the ion beam. (author)

  16. Application of radiofrequency superconductivity to accelerators for high-current ion beams

    International Nuclear Information System (INIS)

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Roche, C.T.; Sagalovsky, L.

    1992-01-01

    A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high-current, high-brightness ion beam. During the last few years, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm) surface areas. Theoretical studies of beam halo, cumulative beam breakup and alternating-phase focusing have also yielded important results. This paper su-summarizes the recent progress and identifies current and future work in the areas of superconducting accelerator technology for high-current ion beams

  17. The impedance of inductive superconducting fault current limiters operating with stacks of thin film Y123/Au washers or bulk Bi2223 rings as secondaries

    International Nuclear Information System (INIS)

    Fernandez, J A Lorenzo; Osorio, M R; Toimil, P; Ferro, G; Blanch, M; Veira, J A; Vidal, F

    2006-01-01

    Inductive fault current limiters operating with stacks of various small superconducting elements acting as secondaries were studied. The stacks consist of Y 1 Ba 2 Cu 3 O 7-δ thin film washers or Bi 1.8 Pb 0.26 Sr 2 Ca 2 Cu 3 O 10+x bulk rings. A central result of our work is an experimental demonstration that the limiting capability of the device is strongly reduced when several bulk rings are stacked, whereas it remains almost unchanged for thin film washers. The use of thin films should therefore allow us to build more efficient high power inductive limiters based on stacks of small washers

  18. Limits of applicability of a time-of-flight ion-mass analyzer in uncovering partial currents of ions emitted by pulsed laser ion sources

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; Láska, Leoš; Rohlena, Karel; Velyhan, Andriy; Czarnecka, A.; Parys, P.; Ryc, L.; Wolowski, J.

    2010-01-01

    Roč. 165, 6-10 (2010), s. 441-450 ISSN 1042-0150 R&D Projects: GA MŠk(CZ) LC528; GA AV ČR IAA100100715 EU Projects: European Commission(XE) 228334 - LASERLAB-EUROPE Institutional research plan: CEZ:AV0Z10100523 Keywords : laser-produced plasma * time-resolved current deconvolution * ion velocity distribution * drift velocity of ions Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.660, year: 2010

  19. Recent results with a high-current, heavy-ion source system

    International Nuclear Information System (INIS)

    Keller, R.; Spaedtke, P.; Emig, H.

    1986-01-01

    In the last conference of this series, an improved high-current ion source for gases, CORDIS was presented. This source has been further developed to allow the processing of substances which are not volatile at room temperature. One of these modifications, HORDIS, incorporates an oven whereas the third version works at rather moderate temperatures and can be fed through a slightly heated external bottle. With this source system, high-current ion beams in the 100 mA range can be produced for a considerable part of the periodic table. Operation parameters and experiences with the sources are discussed, and the most recent results for all versions are given. (author)

  20. Comparison of experimental target currents with analytical model results for plasma immersion ion implantation

    International Nuclear Information System (INIS)

    En, W.G.; Lieberman, M.A.; Cheung, N.W.

    1995-01-01

    Ion implantation is a standard fabrication technique used in semiconductor manufacturing. Implantation has also been used to modify the surface properties of materials to improve their resistance to wear, corrosion and fatigue. However, conventional ion implanters require complex optics to scan a narrow ion beam across the target to achieve implantation uniformity. An alternative implantation technique, called Plasma Immersion Ion Implantation (PIII), immerses the target into a plasma. The ions are extracted from the plasma directly and accelerated by applying negative high-voltage pulses to the target. An analytical model of the voltage and current characteristics of a remote plasma is presented. The model simulates the ion, electron and secondary electron currents induced before, during and after a high voltage negative pulse is applied to a target immersed in a plasma. The model also includes analytical relations that describe the sheath expansion and collapse due to negative high voltage pulses. The sheath collapse is found to be important for high repetition rate pulses. Good correlation is shown between the model and experiment for a wide variety of voltage pulses and plasma conditions

  1. Advanced electrical current measurements of microdischarges: evidence of sub-critical pulses and ion currents in barrier discharge in air

    Science.gov (United States)

    Synek, Petr; Zemánek, Miroslav; Kudrle, Vít; Hoder, Tomáš

    2018-04-01

    Electrical current measurements in corona or barrier microdischarges are a challenge as they require both high temporal resolution and a large dynamic range of the current probe used. In this article, we apply a simple self-assembled current probe and compare it to commercial ones. An analysis in the time and frequency domain is carried out. Moreover, an improved methodology is presented, enabling both temporal resolution in sub-nanosecond times and current sensitivity in the order of tens of micro-amperes. Combining this methodology with a high-tech oscilloscope and self-developed software, a unique statistical analysis of currents in volume barrier discharge driven in atmospheric-pressure air is made for over 80 consecutive periods of a 15 kHz applied voltage. We reveal the presence of repetitive sub-critical current pulses and conclude that these can be identified with the discharging of surface charge microdomains. Moreover, extremely low, long-lasting microsecond currents were detected which are caused by ion flow, and are analysed in detail. The statistical behaviour presented gives deeper insight into the discharge physics of these usually undetectable current signals.

  2. Aberrations due to solenoid focusing of a multiply charged high-current ion beam

    CERN Document Server

    Grégoire, G; Lisi, N; Schnuriger, J C; Scrivens, R; Tambini, J

    2000-01-01

    At the output of a laser ion source, a high current of highly charged ions with a large range of charge states is available. The focusing of such a beam by magnetic elements causes a nonlinear space-charge field to develop which can induce large aberrations and emittance growth in the beam. Simulation of the beam from the CERN laser ion source will be presented for an ideal magnetic and electrostatic system using a radially symmetric model. In addition, the three dimensional software KOBRA3 is used for the simulation of the solenoid line. The results of these simulations will be compared with experiments performed on the CERN laser ion source with solenoids (resulting in a hollow beam) and a series of gridded electrostatic lenses. (5 refs).

  3. The Ring Counter (RCo): A high resolution IC-Si-CsI(Tl) device for heavy ion reaction studies at 10-30 MeV/A

    International Nuclear Information System (INIS)

    Moroni, A.; Bruno, M.; Bardelli, L.; Barlini, S.; Brambilla, S.; Casini, G.; Cavaletti, R.; Chiari, M.; Cortesi, A.; D'Agostino, M.; De Sanctis, J.; Geraci, E.; Giordano, G.; Giussani, A.; Gramegna, F.; Guiot, B.; Kravchuk, V.; Lanchais, A.; Margagliotti, G.V.; Nannini, A.; Ordine, A.; Piantelli, S.; Vannini, G.; Vannucci, L.

    2006-01-01

    An annular detector (Ring Counter, RCo) is presented, which has been designed and built to detect and identify in mass and charge light charged particles and fragments with very low energy thresholds and high energy resolution. It complements the GARFIELD apparatus, operating at INFN Laboratori Nazionali di Legnaro, to detect the forward emitted products of nuclear heavy ion reactions. It consists of eight sectors of a three-stage telescope, each one formed by an ionization chamber followed by eight strips of a silicon detector and by two CsI(Tl) scintillators. Construction features and performances are described and discussed in details

  4. Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion

    Energy Technology Data Exchange (ETDEWEB)

    Cornejo, J. M.; Colombano, M.; Doménech, J.; Rodríguez, D., E-mail: danielrodriguez@ugr.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, 18071 Granada (Spain); Block, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institut Mainz, 55099 Mainz (Germany); Institut für Kernchemie, University of Mainz, 55099 Mainz (Germany); Delahaye, P. [Grand Accélérateur National d’Ions Lourds, 14000 Caen (France)

    2015-10-15

    A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single {sup 40}Ca{sup +} ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on {sup 40}Ca{sup +} ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

  5. Photoinduced currents in pristine and ion irradiated kapton-H polyimide

    Science.gov (United States)

    Sharma, Anu; Sridharbabu, Y.; Quamara, J. K.

    2014-10-01

    The photoinduced currents in pristine and ion irradiated kapton-H polyimide have been investigated for different applied electric fields at 200°C. Particularly the effect of illumination intensity on the maximum current obtained as a result of photoinduced polarization has been studied. Samples were irradiated by using PELLETRON facility, IUAC, New Delhi. The photo-carrier charge generation depends directly on intensity of illumination. The samples irradiated at higher fluence show a decrease in the peak current with intensity of illumination. The secondary radiation induced crystallinity (SRIC) is responsible for the increase in maximum photoinduced currents generated with intensity of illumination.

  6. Photoinduced currents in pristine and ion irradiated kapton-H polyimide

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anu, E-mail: sharmaanu81@gmail.com; Sridharbabu, Y., E-mail: sharmaanu81@gmail.com; Quamara, J. K., E-mail: sharmaanu81@gmail.com [Physics Department, SGTB Khalsa college, Delhi University, Delhi (India); Department of Physics, National Institute of Technology, Kurukshetra-136119 (India); Echelon Group of Institutions, Faridabad (India)

    2014-10-15

    The photoinduced currents in pristine and ion irradiated kapton-H polyimide have been investigated for different applied electric fields at 200°C. Particularly the effect of illumination intensity on the maximum current obtained as a result of photoinduced polarization has been studied. Samples were irradiated by using PELLETRON facility, IUAC, New Delhi. The photo-carrier charge generation depends directly on intensity of illumination. The samples irradiated at higher fluence show a decrease in the peak current with intensity of illumination. The secondary radiation induced crystallinity (SRIC) is responsible for the increase in maximum photoinduced currents generated with intensity of illumination.

  7. The effect of plasma parameter on the bootstrap current of fast ions in neutral beam injection

    International Nuclear Information System (INIS)

    Huang Qianhong; Gong Xueyu; Cao Jinjia; Yang Lei

    2014-01-01

    The effect of plasma parameters on the distribution of net current density of fast ions produced by neutral beam injection is investigated in a large-aspect-ratio Tokamak with circular cross-section under specific parameters. Numerical results show that the value of net current density increases with the temperature of plasma increasing and decreases with the density of plasma increasing. The value of net current density is weakly affected by the effective charge number, but the peak of net current density moves towards edge plasma with effective charge number increasing. (authors)

  8. Nernst-Planck modeling of multicomponent ion transport in a Nafion membrane at high current density

    NARCIS (Netherlands)

    Moshtari Khah, S.; Oppers, N.A.W.; de Groot, M.T.; Keurentjes, J.T.F.; Schouten, J.C.; van der Schaaf, J.

    A mathematical model of multicomponent ion transport through a cation-exchange membrane is developed based on the Nernst–Planck equation. A correlation for the non-linear potential gradient is derived from current density relation with fluxes. The boundary conditions are determined with the Donnan

  9. Transient current induced in thin film diamonds by swift heavy ions

    International Nuclear Information System (INIS)

    Sato, Shin-ichiro; Makino, Takahiro; Ohshima, Takeshi; Kamiya, Tomihiro; Kada, Wataru

    2017-01-01

    Single crystal diamond is a suitable material for the next generation particle detectors because of the superior electrical properties and the high radiation tolerance. In order to investigate charge transport properties of diamond particle detectors, transient currents generated in diamonds by single swift heavy ions (26 MeV O 5+ and 45 MeV Si 7+ ) are investigated. We also measured two dimensional maps of transient currents by single ion hits. In the case of 50 μm-thick diamond, both the signal height and the collected charge are reduced by the subsequent ion hits and the charge collection time is extended. Our results are thought to be attributable to the polarization effect in diamond and it appears only when the transient current is dominated by hole current. In the case of 6 μm-thick diamond membrane, an “island” structure is found in the 2D map of transient currents. Signals in the islands shows different applied bias dependence from signals in other regions, indicating different crystal and/or metal contact quality. Simulation study of transient currents based on the Shockley-Ramo theorem clarifies that accumulation of space charges changes distribution of electric field in diamond and causes the polarization effect.

  10. Reconstruction of the ion plasma parameters from the current measurements: mathematical tool

    Directory of Open Access Journals (Sweden)

    E. Séran

    Full Text Available Instrument d’Analyse du Plasma (IAP is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i retarding potential analyser (APR, which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii velocity direction analyser (ADV, which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i finite angular aperture, (ii grid transparency, (iii potential depression in the space between the grid wires, (iv losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI model.

    Key words. Ionosphere (plasma convection; instruments and techniques – Space plasma physics (experimental and mathematical techniques

  11. Reconstruction of the ion plasma parameters from the current measurements: mathematical tool

    Directory of Open Access Journals (Sweden)

    E. Séran

    2003-05-01

    Full Text Available Instrument d’Analyse du Plasma (IAP is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i retarding potential analyser (APR, which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii velocity direction analyser (ADV, which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i finite angular aperture, (ii grid transparency, (iii potential depression in the space between the grid wires, (iv losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI model.Key words. Ionosphere (plasma convection; instruments and techniques – Space plasma physics (experimental and mathematical techniques

  12. Conditioning of BPM pickup signals for operations of the Duke storage ring with a wide range of single-bunch current

    Science.gov (United States)

    Xu, Wei; Li, Jing-Yi; Huang, Sen-Lin; Z. Wu, W.; Hao, H.; P., Wang; K. Wu, Y.

    2014-10-01

    The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers (FELs), and the High Intensity Gamma-ray Source (HIGS). It is operated with a beam current ranging from about 1 mA to 100 mA per bunch for various operations and accelerator physics studies. High performance operations of the FEL and γ-ray source require a stable electron beam orbit, which has been realized by the global orbit feedback system. As a critical part of the orbit feedback system, the electron beam position monitors (BPMs) are required to be able to precisely measure the electron beam orbit in a wide range of the single-bunch current. However, the high peak voltage of the BPM pickups associated with high single-bunch current degrades the performance of the BPM electronics, and can potentially damage the BPM electronics. A signal conditioning method using low pass filters is developed to reduce the peak voltage to protect the BPM electronics, and to make the BPMs capable of working with a wide range of single-bunch current. Simulations and electron beam based tests are performed. The results show that the Duke storage ring BPM system is capable of providing precise orbit measurements to ensure highly stable FEL and HIGS operations.

  13. Research on generation mechanism of single event transient current generated in the semiconductor using ion accelerator

    International Nuclear Information System (INIS)

    Hirao, Toshio

    2007-01-01

    Single-event upset (SEU) is triggered when an amount of electric charges induced by energetic ion incidence exceeds a value known as a critical charge in a very short time period. Therefore, accurate evaluation of electric charge and understanding of basic mechanism of SEU are necessary for the improvement of SEU torrance of electronic devices. In this paper, the collected charges for the single event transient current induced on semiconductor by heavy ion microbeams, and application to use microbeam for single event studies are presented. (author)

  14. Description of current pulses induced by heavy ions in silicon detectors (II)

    Energy Technology Data Exchange (ETDEWEB)

    Hamrita, H. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette Cedex (France); Parlog, M. [LPC, CNRS/IN2P3, ENSICAEN, Universite de Caen, F-14050 Caen Cedex (France); National Institute for Physics and Nuclear Engineering, RO-76900 Bucharest-Magurele (Romania); Borderie, B., E-mail: borderie@ipno.in2p3.fr [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Lavergne, L. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Le Neindre, N. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); LPC, CNRS/IN2P3, ENSICAEN, Universite de Caen, F-14050 Caen Cedex (France); Rivet, M.F.; Barbey, S. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Bougault, R. [LPC, CNRS/IN2P3, ENSICAEN, Universite de Caen, F-14050 Caen Cedex (France); Chabot, M. [Inst. de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay Cedex (France); Chbihi, A. [GANIL (DSM-CEA/CNRS/IN2P3), F-14076 Caen Cedex (France); Cussol, D. [LPC, CNRS/IN2P3, ENSICAEN, Univ. de Caen, F-14050 Caen Cedex (France); Oliveira Santos, F. de [GANIL (DSM-CEA/CNRS/IN2P3), F-14076 Caen Cedex (France); Edelbruck, P. [Inst. de Physique Nucleaire, CNRS/IN2P3, Univ. Paris-Sud 11, F-91406 Orsay Cedex (France); Frankland, J.D. [GANIL (DSM-CEA/CNRS/IN2P3), F-14076 Caen Cedex (France); Galichet, E. [Inst. de Physique Nucleaire, CNRS/IN2P3, Univ. Paris-Sud 11, F-91406 Orsay Cedex (France); Conservatoire National des Arts et Metier, F-75141 Paris Cedex 03 (France); Guinet, D.; Lautesse, Ph. [Inst. de Physique Nucleaire, CNRS/IN2P3, Univ.e Claude Bernard Lyon I, F-69622 Villeurbanne Cedex (France); Lopez, O. [LPC, CNRS/IN2P3, ENSICAEN, Univ. de Caen, F-14050 Caen Cedex (France)

    2011-06-21

    Current pulses induced in a silicon detector by 10 different heavy ion species at known energies around 10 A MeV have been sampled in time at high frequency. Their individual average shapes are quite well reproduced by a fit procedure based on our recent charge carrier collection treatment which considers the progressive extraction of the electrons and holes from the high carrier density zone along the ionizing particle track. This region is assumed to present a supplementary dielectric polarization and consequently a disturbed electric field. The influence of the nature of the heavy ion on the values of the three fit parameters is analyzed.

  15. Current signal of silicon detectors facing charged particles and heavy ions

    International Nuclear Information System (INIS)

    Hamrita, H.

    2005-07-01

    This work consisted in collecting and studying for the first time the shapes of current signals obtained from charged particles or heavy ions produced by silicon detectors. The document is divided into two main parts. The first consisted in reducing the experimental data obtained with charged particles as well as with heavy ions. These experiments were performed at the Orsay Tandem and at GANIL using LISE. These two experiments enabled us to create a data base formed of current signals with various shapes and various times of collection. The second part consisted in carrying out a simulation of the current signals obtained from the various ions. To obtain this simulation we propose a new model describing the formation of the signal. We used the data base of the signals obtained in experiments in order to constrain the three parameters of our model. In this model, the charge carriers created are regarded as dipoles and their density is related to the dielectric polarization in the silicon detector. This phenomenon induces an increase in permittivity throughout the range of the incident ion and consequently the electric field between the electrodes of the detector is decreased inside the trace. We coupled with this phenomenon a dissociation and extraction mode of the charge carriers so that they can be moved in the electric field. (author)

  16. Effects of tacrolimus on action potential configuration and transmembrane ion currents in canine ventricular cells.

    Science.gov (United States)

    Szabó, László; Szentandrássy, Norbert; Kistamás, Kornél; Hegyi, Bence; Ruzsnavszky, Ferenc; Váczi, Krisztina; Horváth, Balázs; Magyar, János; Bányász, Tamás; Pál, Balázs; Nánási, Péter P

    2013-03-01

    Tacrolimus is a commonly used immunosuppressive agent which causes cardiovascular complications, e.g., hypertension and hypertrophic cardiomyopathy. In spite of it, there is little information on the cellular cardiac effects of the immunosuppressive agent tacrolimus in larger mammals. In the present study, therefore, the concentration-dependent effects of tacrolimus on action potential morphology and the underlying ion currents were studied in canine ventricular cardiomyocytes. Standard microelectrode, conventional whole cell patch clamp, and action potential voltage clamp techniques were applied in myocytes enzymatically dispersed from canine ventricular myocardium. Tacrolimus (3-30 μM) caused a concentration-dependent reduction of maximum velocity of depolarization and repolarization, action potential amplitude, phase-1 repolarization, action potential duration, and plateau potential, while no significant change in the resting membrane potential was observed. Conventional voltage clamp experiments revealed that tacrolimus concentrations ≥3 μM blocked a variety of ion currents, including I(Ca), I(to), I(K1), I(Kr), and I(Ks). Similar results were obtained under action potential voltage clamp conditions. These effects of tacrolimus developed rapidly and were fully reversible upon washout. The blockade of inward currents with the concomitant shortening of action potential duration in canine myocytes is the opposite of those observed previously with tacrolimus in small rodents. It is concluded that although tacrolimus blocks several ion channels at higher concentrations, there is no risk of direct interaction with cardiac ion channels when applying tacrolimus in therapeutic concentrations.

  17. Ion energy spectrum just after the application of current pulse for turbulent heating in the TRIAM-1 tokamak

    International Nuclear Information System (INIS)

    Nakamura, Kazuo; Nakamura, Yukio; Hiraki, Naoji; Itoh, Satoshi

    1981-01-01

    Temporal evolution and spatial profile of ion energy spectrum just after the application of current pulse for turbulent heating are investigated experimentally in TRIAM-1 and numerically with a Fokker-Planck equation. Two-component ion energy spectrum formed by turbulent heating relaxes to single one within tau sub(i) (ion collision time). (author)

  18. Ion energy spectrum just after the application of current pulse for turbulent heating in the TRIAM-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K; Nakamura, Y; Hiraki, N; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1981-07-01

    Temporal evolution and spatial profile of ion energy spectrum just after the application of current pulse for turbulent heating are investigated experimentally in TRIAM-1 and numerically with a Fokker-Planck equation. Two-component ion energy spectrum formed by turbulent heating relaxes to single one within tau sub(i) (ion collision time).

  19. Storm-associated variations of equatorially mirroring ring current protons, 1--800 keV, at constant first adiabatic invariant

    International Nuclear Information System (INIS)

    Lyons, L.R.; Williams, D.J.

    1976-01-01

    Explorer 45 observations of ring current protons mirroring near the equator, 1--800 keV, are presented at constant first adiabatic invariant μ throughout the period of the December 17, 1971, geomagnetic storm. To obtain μ, simultaneous magnetic field and particle observations are used. Particle deceleration in response to the storm time magnetic field decrease causes ring current measurements viewed at constant energy to underestimate the storm time increase in proton intensities at energies approximately-less-than200 keV. This adiabatic deceleration also accounts for the large flux decreases observed at energies approximately-greater-than200 keV during the storm, in contradiction with previous results (Soraas and Davis, 1968) obtained using a model for the storm time magnetic field

  20. Laser system for cooling of relativistic C{sup 3+}-ion beams in storage rings; Lasersystem zur Kuehlung relativistischer C{sup 3+}-Ionenstrahlen in Speicherringen

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Tobias

    2015-02-15

    Cold ion beams are essential for many precision experiments at storage rings. While spectroscopic experiments gain from the high energy resolution, collision experiments benefit from the increased luminosity. Furthermore, sympathetic cooling of exotic species is conceivable with the aid of cold ion beams. Besides the long established electron cooling, alternative cooling methods are gaining in importance, especially for high energy particles. In the past, experiments to cool ions with lasers were performed. Because of the matching wavelength and output power, frequency doubled Argon-ion lasers at 257 nm were used during these experiments. Due to the strongly limited scanning potential of these systems, it was not possible to cool the full inertia spread of the ion beams. A new laser system was developed in this thesis because of the lack of commercial alternatives. After the characterization of the system, it was tested during a beamtime at the Experimentierspeicherring (ESR) at the Gesellschaft fuer Schwerionenforschung (GSI). The completely solid state based system delivers up to 180 mW of output power at 257 nm and is modehop free tunable up to 16 GHz in 10 ms at this wavelength. By using efficient diode lasers, the new system consumes considerably less power than comparable Argon-ion lasers. The fundamental wavelength of 1028 nm is amplified up to 16 W with an Yb-doped fiber amplifier. Subsequently, the target wavelength of 257 nm is realized in two consecutive build-up cavities. Another diode laser, stabilized to a wavelength meter, serves as a frequency reference. This new laser system first came to operation during beamtime in August 2012, when relativistic C{sup 3+} ions with β=0.47 were cooled successfully. For the first time it was possible to access the whole inertia spread of a bunched ion beam without electron precooling. In contrast to prior experiments, only the laser frequency was scanned and not the bunching frequency of the ion beam. The results

  1. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe{sub 2}O{sub 3}@Carbon anodes for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan-Hui, E-mail: sunyanhui0102@163.com; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-12-30

    Core-shell nano-ring α-Fe{sub 2}O{sub 3}@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe{sub 2}O{sub 3} nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe{sub 2}O{sub 3} (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe{sub 2}O{sub 3} during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g{sup −1} and retains 920/897 mAh g{sup −1} after 200 cycles at 500 mA g{sup −1} (0.5C). Even at 2000 mA g{sup −1} (2C), the electrode delivers the initial capacities of 1400/900 mAh g{sup −1}, and still maintains 630/610 mAh g{sup −1} after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe{sub 2}O{sub 3}@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe{sub 2}O{sub 3} and facilitate the transportation of electrons and Li{sup +} ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe{sub 2}O{sub 3}@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  2. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe_2O_3@Carbon anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-01-01

    Core-shell nano-ring α-Fe_2O_3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe_2O_3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe_2O_3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe_2O_3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g"−"1 and retains 920/897 mAh g"−"1 after 200 cycles at 500 mA g"−"1 (0.5C). Even at 2000 mA g"−"1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g"−"1, and still maintains 630/610 mAh g"−"1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe_2O_3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe_2O_3 and facilitate the transportation of electrons and Li"+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe_2O_3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  3. Electrochemical performance and structure evolution of core-shell nano-ring α-Fe2O3@Carbon anodes for lithium-ion batteries

    Science.gov (United States)

    Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

    2016-12-01

    Core-shell nano-ring α-Fe2O3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe2O3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe2O3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe2O3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g-1 and retains 920/897 mAh g-1 after 200 cycles at 500 mA g-1 (0.5C). Even at 2000 mA g-1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g-1, and still maintains 630/610 mAh g-1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe2O3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe2O3 and facilitate the transportation of electrons and Li+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe2O3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

  4. Contribution of the backstreaming ions to the Self-Magnetic pinch (SMP) diode current

    Energy Technology Data Exchange (ETDEWEB)

    Mazarakis, Michael G.; Cuneo, Michael E.; Fournier, Sean D.; Johnston, Mark D.; Kiefer, Mark L.; Leckbee, Joshua J.; Nielsen, Dan S.; Oliver, Bryan V.; Simpson, Sean; Renk, Timothy J.; Webb, Timothy J.; Ziska, Derek; Bennett, Nichelle; Droemer, Darryl W.; Cignac, Raymond E.; Obregon, Robert J.; Smith, Chase C.; Wilkins, Frank L.; Welch, Dale R.

    2016-08-08

    Summary form only given. The results presented here were obtained with an SMP diode mounted at the front high voltage end of the RITS accelerator. RITS is a Self-Magnetically Insulated Transmission Line (MITL) voltage adder that adds the voltage pulses of six 1.3 MV inductively insulated cavities. Our experiments had two objectives: first to measure the contribution of the back-streaming ion currents emitted from the anode target to the diode beam current, and second to try to evaluate the energy of those ions and hence the actual Anode-Cathode (A-K) gap actual voltage. In any very high voltage inductive voltage adder (IVA) utilizing MITLs to transmit the power to the diode load, the precise knowledge of the accelerating voltage applied on the anode-cathode (A-K) gap is problematic. The accelerating voltage quoted in the literature is from estimates based on measurements of the anode and cathode currents of the MITL far upstream from the diode and utilizing the para-potential flow theories and inductive corrections. Thus it would be interesting to have another independent measurement to evaluate the A-K voltage. The diode's anode is made of a number of high Z metals in order to produce copious and energetic flash x-rays. The backstreaming currents are a strong fraction of the anode materials and their stage of cleanness and gas adsorption. We have measured the back-streaming ion currents emitted from the anode and propagating through a hollow cathode tip for various diode configurations and different techniques of target cleaning treatments, such as heating to very high temperatures with DC and pulsed current, with RF plasma cleaning and with both plasma cleaning and heating. Finally, we have also evaluated the A-K gap voltage by ion filtering techniques.

  5. Dielectronic recombination experiments at the storage rings: From the present CSR to the future HIAF

    Science.gov (United States)

    Huang, Z. K.; Wen, W. Q.; Xu, X.; Wang, H. B.; Dou, L. J.; Chuai, X. Y.; Zhu, X. L.; Zhao, D. M.; Li, J.; Ma, X. M.; Mao, L. J.; Yang, J. C.; Yuan, Y. J.; Xu, W. Q.; Xie, L. Y.; Xu, T. H.; Yao, K.; Dong, C. Z.; Zhu, L. F.; Ma, X.

    2017-10-01

    Dielectronic recombination (DR) experiments of highly charged ions at the storage rings have been developed as a precision spectroscopic tool to investigate the atomic structure as well as nuclear properties of stable and unstable nuclei. The DR experiment on lithium-like argon ions was successfully performed at main Cooler Storage Ring (CSRm) at Heavy Ion Research Facility in Lanzhou (HIRFL) accelerator complex. The DR experiments on heavy highly charged ions and even radioactive ions are currently under preparation at the experimental Cooler Storage Ring (CSRe) at HIRFL. The current status of DR experiments at the CSRm and the preparation of the DR experiments at the CSRe are presented. In addition, an overview of DR experiments by employing an electron cooler and a separated ultra-cold electron target at the upcoming High Intensity heavy ion Accelerator Facility (HIAF) will be given.

  6. Overview of the current spectroscopy effort on the Livermore electron beam ion traps

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; Lopez-Urrutia, J.C.; Brown, G.

    1995-01-01

    An overview is given of the current spectroscopic effort on the Livermore electron beam ion trap facilities. The effort focuses on four aspects: spectral line position, line intensity, temporal evolution, and line shape. Examples of line position measurements include studies of the K-shell transitions in heliumlike Kr 34+ and the 2s-2p intrashell transitions in lithiumlike Th 87+ and U 89+ , which provide benchmark values for testing the theory of relativistic and quantum electrodynamical contributions in high-Z ions. Examples of line intensity measurements are provided by measurements of the electron-impact excitation and dielectronic recombination cross sections of heliumlike transition-metal ions Ti 20+ through CO 25+ . A discussion of radiative lifetime measurements of metastable levels in heliumlike ions is given to illustrate the time-resolved spectroscopy techniques in the microsecond range. The authors also present a measurement of the spectral lineshape that illustrates the very low ion temperatures that can be achieved in an EBIT

  7. A low-cost non-intercepting beam current and phase monitor for heavy ions

    International Nuclear Information System (INIS)

    Bogaty, J.M.; Clifft, B.E.

    1995-01-01

    A low cost ion beam measurement system has been developed for use at ATLAS. The system provides nondestructive phase and intensity measurement of passing ion beam bunches by sensing their electric fields. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum jacket where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam induced radiofrequency signals are summed against an offset frequency generated by the master oscillator. The resulting difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop to stabilize phase readings during microsecond beam drop outs. The other channel uses a linear full-wave active rectifier circuit which converts sine wave signal amplitude to a DC voltage representing beam current. Plans are in progress to install this new diagnostic at several locations in ATLAS which should help shorten the tuning cycle of new ion species

  8. The FERRUM project: an extremely long radiative lifetime in Ti II measured in an ion storage ring

    International Nuclear Information System (INIS)

    Hartman, H; Rostohar, D; Derkatch, A; Lundin, P; Schef, P; Johansson, S; Lundberg, H; Mannervik, S; Norlin, L-O; Royen, P

    2003-01-01

    We have extended the laser probing technique at the CRYRING storage ring to measurement of the extremely long lifetime (28 s) of the metastable 3d 2 ( 3 P)4s b 4 P 5/2 level in Ti II. The result obtained demonstrates the power of this method for investigation of such long-lived levels. This is the first experimental lifetime investigation of metastable states in Ti II. (letter to the editor)

  9. Development of an IH-type linac for the acceleration of high current heavy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Haehnel, Jan Hendrik

    2017-07-20

    The Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt will provide unprecedented intensities of protons and heavy ions up to uranium at energies of up to 29 GeV for protons and 2.7 GeV/u for U{sup 28+}. To achieve high intensities in the synchrotron accelerators, high beam currents have to be provided by the injector linear accelerators. High current heavy ion beams are provided by the Universal Linear Accelerator (UNILAC), which in its current state will not be able to provide the required FAIR beam currents. This thesis deals with the development of upgrades for the UNILAC to ensure its high current capability. The first improvement is a matching section (MEBT) for the interface between the RFQ and the IH-DTL of the existing high current injector HSI at the UNILAC. With this new MEBT section, particle losses are eliminated and the overall beam quality is improved. As a second improvement, a complete replacement of the existing Alvarez-DTL is presented. A combination of efficient IH-type cavities and KONUS beam dynamics results in a reduction of the linac length from about 60 m (Alvarez) to just 23 m (new IH-DTL) while providing the same energy and fulfilling FAIR requirements of a high beam current and beam quality. This thesis contains a detailed beam dynamics design of the new linac including some fundamental investigations of the KONUS beam dynamics concept. A cross-check of the beam dynamics design was performed with two independent multi-particle simulation codes. Detailed error studies were conducted to investigate the influence of manufacturing, alignment and operating errors on the beam dynamics performance. Additionally, all five linac cavities were designed, optimized, and their RF parameters including power requirements calculated to provide a comprehensive linac design.

  10. Development of an IH-type linac for the acceleration of high current heavy ion beams

    International Nuclear Information System (INIS)

    Haehnel, Jan Hendrik

    2017-01-01

    The Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt will provide unprecedented intensities of protons and heavy ions up to uranium at energies of up to 29 GeV for protons and 2.7 GeV/u for U 28+ . To achieve high intensities in the synchrotron accelerators, high beam currents have to be provided by the injector linear accelerators. High current heavy ion beams are provided by the Universal Linear Accelerator (UNILAC), which in its current state will not be able to provide the required FAIR beam currents. This thesis deals with the development of upgrades for the UNILAC to ensure its high current capability. The first improvement is a matching section (MEBT) for the interface between the RFQ and the IH-DTL of the existing high current injector HSI at the UNILAC. With this new MEBT section, particle losses are eliminated and the overall beam quality is improved. As a second improvement, a complete replacement of the existing Alvarez-DTL is presented. A combination of efficient IH-type cavities and KONUS beam dynamics results in a reduction of the linac length from about 60 m (Alvarez) to just 23 m (new IH-DTL) while providing the same energy and fulfilling FAIR requirements of a high beam current and beam quality. This thesis contains a detailed beam dynamics design of the new linac including some fundamental investigations of the KONUS beam dynamics concept. A cross-check of the beam dynamics design was performed with two independent multi-particle simulation codes. Detailed error studies were conducted to investigate the influence of manufacturing, alignment and operating errors on the beam dynamics performance. Additionally, all five linac cavities were designed, optimized, and their RF parameters including power requirements calculated to provide a comprehensive linac design.

  11. The Current-Driven, Ion-Acoustic Instability in a Collisionless Plasma

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1979-01-01

    The current-driven, ion-acoustic instability was investigated by means of an experiment performed in a collisionless plasma produced in a single-ended Q-machine. Reflections at the ends of the plasma column gave rise to a standing wave. Parameters of the instability were investigated, and it was ......, and it was demonstrated that the fluctuations in the plasma column behave as a classical Van der Pol oscillator. Accurate measurements of the growth rate of the instability can be performed by making explicit use of the particular properties of such a system.......The current-driven, ion-acoustic instability was investigated by means of an experiment performed in a collisionless plasma produced in a single-ended Q-machine. Reflections at the ends of the plasma column gave rise to a standing wave. Parameters of the instability were investigated...

  12. Current developments with TRIUMF’s titanium-sapphire laser based resonance ionization laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, J., E-mail: LASSEN@triumf.ca; Li, R. [TRIUMF (Canada); Raeder, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Zhao, X.; Dekker, T. [TRIUMF (Canada); Heggen, H. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Kunz, P.; Levy, C. D. P.; Mostanmand, M.; Teigelhöfer, A.; Ames, F. [TRIUMF (Canada)

    2017-11-15

    Developments at TRIUMF’s isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

  13. Characterisation Of The Beam Plasma In High Current, Low Energy Ion Beams For Implanters

    International Nuclear Information System (INIS)

    Fiala, J.; Armour, D. G.; Berg, J. A. van der; Holmes, A. J. T.; Goldberg, R. D.; Collart, E. H. J.

    2006-01-01

    The effective transport of high current, positive ion beams at low energies in ion implanters requires the a high level of space charge compensation. The self-induced or forced introduction of electrons is known to result in the creation of a so-called beam plasma through which the beam propagates. Despite the ability of beams at energies above about 3-5 keV to create their own neutralising plasmas and the development of highly effective, plasma based neutralising systems for low energy beams, very little is known about the nature of beam plasmas and how their characteristics and capabilities depend on beam current, beam energy and beamline pressure. These issues have been addressed in a detailed scanning Langmuir probe study of the plasmas created in beams passing through the post-analysis section of a commercial, high current ion implanter. Combined with Faraday cup measurements of the rate of loss of beam current in the same region due to charge exchange and scattering collisions, the probe data have provided a valuable insight into the nature of the slow ion and electron production and loss processes. Two distinct electron energy distribution functions are observed with electron temperatures ≥ 25 V and around 1 eV. The fast electrons observed must be produced in their energetic state. By studying the properties of the beam plasma as a function of the beam and beamline parameters, information on the ways in which the plasma and the beam interact to reduce beam blow-up and retain a stable plasma has been obtained

  14. Miniature excitatory synaptic ion currents in the earthworm Lumbricus terrestris body wall muscles

    Czech Academy of Sciences Publication Activity Database

    Volkov, E. M.; Nurullin, L. F.; Nikolsky, E.; Vyskočil, František

    2007-01-01

    Roč. 56, č. 5 (2007), s. 655-658 ISSN 0862-8408 R&D Projects: GA AV ČR(CZ) IAA5011411 Grant - others:RFBR(RU) 06-04-48458; Nsh(RU) 4444.2006.4 Institutional research plan: CEZ:AV0Z50110509 Keywords : ion currents * muscle cells * acetylcholine receptor Subject RIV: ED - Physiology Impact factor: 1.505, year: 2007

  15. Estimation of plasma ion saturation current and reduced tip arcing using Langmuir probe harmonics.

    Science.gov (United States)

    Boedo, J A; Rudakov, D L

    2017-03-01

    We present a method to calculate the ion saturation current, I sat , for Langmuir probes at high frequency (>100 kHz) using the harmonics technique and we compare that to a direct measurement of I sat . It is noted that the I sat estimation can be made directly by the ratio of harmonic amplitudes, without explicitly calculating T e . We also demonstrate that since the probe tips using the harmonic method are oscillating near the floating potential, drawing little power, this method reduces tip heating and arcing and allows plasma density measurements at a plasma power flux that would cause continuously biased tips to arc. A multi-probe array is used, with two spatially separated tips employing the harmonics technique and measuring the amplitude of at least two harmonics per tip. A third tip, located between the other two, measures the ion saturation current directly. We compare the measured and calculated ion saturation currents for a variety of plasma conditions and demonstrate the validity of the technique and its use in reducing arcs.

  16. Design considerations for the Cornell megavolt ion coil experiment (MICE)

    International Nuclear Information System (INIS)

    Jayakumar, R.; Podulka, B.; Keller, S.; Milks, J.; Fleischmann, H.H.

    1986-01-01

    Field reversing ion rings offer an attractive alternative plasma confinement scheme in which a Compact Torus is formed with axis-encircling ion currents. An experiment on forming MeV ion rings-MICE, is under construction in this group. This experiment will prepare the physics base for application of ion rings to the tilt stabilization and/or heating of the larger near-future CT plasma experiments, which will need ion rings with energies of 1-2 MeV. The MICE experiments will therefore extend other experiments to stronger rings with MeV ions. The MICE experiment will employ a Marx generator operating at about 1 MV, coupled to a magnetically insulated ion diode. The ion beam so generated will be passed through a magnetic cusp region, where the axial beam energy will be converted into rotational energy. Gas will be puffed in the trapping region for charge neutralization of the beam. Various methods, including resistive image currents, pulsed fields and phase focussing are being considered for ring trapping. In the present first stage of the experiment, investigation of ion diode behavior and ring formation will be emphasized. A schematic of the proposed experimental arrangement is shown and the major parameters of the experiment are given. The various subsystems follows are described

  17. Measurement of electron- and ion beam energies and currents in a plasma focus discharge

    International Nuclear Information System (INIS)

    Yamamoto, Toshikazu; Kondoh, Yoshiomi; Shimoda, Katsuji; Hirano, Katsumi

    1982-01-01

    Measurements of energetic particle beams in a plsma focus with a Mather type device are presented. Rogowski coils are used for time-resolved measurement, and solid-state nuclear track detectors for time-integrated measurement of the beams. In the upstream direction with respect to the discharge current, only the electron beam with the maximum current of several kA was detected, which was approximately one percent of the discharge current. The electron energies of the beam were spread from 0.1 to 1 MeV. In the downstream direction, two successive emissions of ions were observed. The first emission had an extremely high energy of the order of some MeV and a low beam current of less than 10 A. The second emission, the main part of the ion beam, with energies of 100 - 800 keV, followed the first one with a time lag of several tens of nanoseconds, and the beam current reached several tens of amperes. (author)

  18. Analysis techniques of charging damage studied on three different high-current ion implanters

    Science.gov (United States)

    Felch, S. B.; Larson, L. A.; Current, M. I.; Lindsey, D. W.

    1989-02-01

    One of the Greater Silicon Valley Implant Users' Group's recent activities has been to sponsor a round-robin on charging damage, where identical wafers were implanted on three different state-of-the-art, high-current ion implanters. The devices studied were thin-dielectric (250 Å SiO2), polysilicon-gate MOS capacitors isolated by thick field oxide. The three implanters involved were the Varian/Extrion 160XP, the Eaton/Nova 10-80, and the Applied Materials PI9000. Each implanter vendor was given 48 wafers to implant with 100 keV As+ ions at a dose of 1 × 1016 cm-2. Parameters that were varied include the beam current, electron flood gun current, and chamber pressure. The charge-to-breakdown, breakdown voltage, and leakage current of several devices before anneal have been measured. The results from these tests were inconclusive as to the physical mechanism of charging and as to the effectiveness of techniques to reduce its impact on devices. However, the methodology of this study is discussed in detail to aid in the planning of future experiments. Authors' industrial affiliations: S.B. Felch, Varian Research Center, 611 Hansen Way, Palo Alto, CA 94303, USA; L.A. Larson, National Semiconductor Corp., P.O. Box 58090, Santa Clara, CA 95052-8090, USA; M.I. Current, Applied Materials, 3050 Bowers Ave., Santa Clara, CA 95054, USA; D.W. Lindsey, Eaton/NOVA, 931 Benicia Ave, Sunnyvale, CA 94086, USA.

  19. Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

    Science.gov (United States)

    Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

    2015-12-01

    BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Conceptual design of a permanent ring magnet based helicon plasma source module intended to be used in a large size fusion grade ion source

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Arun; Sudhir, Dass; Bandyopadhyay, M., E-mail: mainak@iter-india.org; Chakraborty, A.

    2016-02-15

    A conceptual design of a permanent magnet based single driver helicon plasma source module along with its design approach is described in this paper. The module unit is intended to be used in a large size ion source. The conceptual design of the helicon source module has been carried out using a computer code, HELIC. The magnetic field topology for the ring magnet is simulated with another code, BFieldM and the magnetic field values obtained from the calculation are further used as input in HELIC calculation for the conceptual design. The module is conceptualized based on a cylindrical glass vessel to produce plasma of diameter ∼50 mm, height ∼50 mm. The inner diameter of the permanent ring magnets is also of the same dimension with thickness ∼10 mm each, placed slightly above the backplate to maintain the required magnetic field. The simulated results show that for hydrogen gas, expected plasma density can be achieved as high as ∼10{sup 12}–10{sup 13} cm{sup −3} in the proposed helicon source configuration using 1 kW 13.56 MHz RF generator. An experimental setup to characterize a Helicon source module unit, consisting of a cylindrical glass (plasma) chamber along with the vacuum system, RF power supplies, probes and data acquisition system is being installed.

  1. Pumping characteristics for H2, CO and gas mixture of H2 and CO of distributed ion pump for the SPring-8 storage ring

    International Nuclear Information System (INIS)

    Hirano, Nobuo; Kobari, Toshiaki; Matsumoto, Manabu

    1995-01-01

    Evacuation in the vacuum chamber of the deflection magnet part of the SPring-8 storage ring is planned to be performed with a non evaporable getter pump (NEG) as well as a distributed ion pump (DIP). Pumping characteristics for H 2 , CO and a gas mixture of H 2 and CO of DIP was investigated. The structure of the DIP constructed on a trial basis and an experimental setup to measure the DIP pumping characteristics were described. Pumping speed above 100 L/s per 1 m at the 10 -6 Pa device and pumping speed of about 500 L/s per 1 m at the 10 -7 Pa device were achieved for a gas mixture of H 2 and CO (37% and 55% CO). On the DIP saturated with CO, pumping speed for H 2 is about twice that of pumping speed for CO at the 10 -7 Pa device. Pumping speed for CO is about 1.5 times of the speed for N 2 at the 10 -6 Pa device. Pressure of 1.2 x 10 -8 Pa (9.0 x 10 -11 Torr) is achieved at a room temperature by baking at 150degC for 40 hr. Thus, it was confirmed that the DIP has sufficient pumping characteristics as a pump for the SPring-8 storage ring. (T.H.)

  2. Effect of chelate ring sizes and their substitution on intensities of hypersensitive transitions of lanthanoids (Ln(III)) ions and j (total quantum number profiles)

    International Nuclear Information System (INIS)

    Dubey, J.; Pandey, P.; Yadav, A.; Limaye, S.N.

    1998-01-01

    Full text: Electronic spectral studies of Pr(III), Nd(III), Sm(III) Dy(III), Eu(III) and Tm(III) complexes with some aliphatic and aromatic O-O donor ligands viz., Glycolic (gly), Malonic (main) Succinic (suc), Glutaric (glut), Salicylic (sal), Phthalic acids and Catechol (cat) having varied chelate ring sizes and different substitutions as side chains have been carried out with a view to study the effect of chelate ring sizes on the intensities of hypersensitive and pseudo-hypersensitive transitions in lanthanoids. The intensities of these HST transitions have also been correlated with the total quantum number (J) of the lanthanoid metal ions in order to seek a probable mechanism for the phenomenon hypersensitivity. A comparison of the spectral and nephelauxetic parameters for Pr(III), Nd(III), Sm(III) with Dy(III) Er(III) and Tm(III) exhibit a variation in the bonding pattern from electrostatic to covalo-electrostatic from pre-Gd elements to post-Gd elements. The J-(total) quantum number profiles of the oscillator strength values for the specific HST transitions have also been examined

  3. Design of an end station for a high current ion implantation system

    International Nuclear Information System (INIS)

    Kranik, J.R.

    1979-01-01

    During the last 4 to 5 years IBM has been involved in an effort to develop a high current Ion Implantation system with pre-deposition capabilities. The system is dedicated to Arsenic implants, involving doses > 1 x 10 15 ions/cm 2 in the energy range of 30 to 60 keV. A major portion of this effort involved the design of an associated end station capable of producing high uniformity implants with beam currents in the 0.5 to 6.0 mA range. The end station contains all components from the exit of the analyzing magnet, including the exit beamline, process chamber, scan system, wafer handling system, high vacuum pumping package, beam optics, dosimetry system, and associated electronic controls. The unit was restricted to a six wafer (82 mm) batch size to maintain process line compatibility. In addition, implant dose non-uniformity objectives were established at +- 3% (2σ) within a wafer and +- 2% (2σ) wafer-to-wafer. Also, the system was to be capable of implanting 24 wafers/hour at a dose of 7.5 x 10 15 ions/cm 2 . Major consideration in the design was afforded to high reliability, ease of maintenance and production level throughput capabilities. The rationale and evolution of the final end station design is described. (author)

  4. Two-point theory of current-driven ion-cyclotron turbulence

    International Nuclear Information System (INIS)

    Chiueh, T.; Diamond, P.H.

    1985-02-01

    An analytical theory of current-driven ion-cyclotron turbulenc which treats incoherent phase space density granulations (clumps) is presented. In contrast to previous investigations, attention is focused on the physically relevant regime of weak collective dissipation, where waves and clumps coexist. The threshold current for nonlinear instability is calculated, and is found to deviate from the linear threshold. A necessary condition for the existence of stationary wave-clump turbulence is derived, and shown to be analogous to the test particle model fluctuation-dissipation theorem result. The structure of three dimensional magnetized clumps is characterized. It is proposed that instability is saturated by collective dissipation due to ion-wave scattering. For this wave-clump turbulence regime, it is found that the fluctuation level (e psi/T/sub e/)/sub rms/ less than or equal to 0.1, and that the modification of anomalous resistivity to levels predicted by conventional nonlinear wave theories is moderate. It is also shown that, in marked contrast to the quasilinear prediction, ion heating significantly exceeds electron heating

  5. Fragmentation of copper current collectors in Li-ion batteries during spherical indentation

    International Nuclear Information System (INIS)

    Wang, Hsin; Watkins, Thomas R.; Simunovic, Srdjan; Bingham, Philip R.; Allu, Srikanth; Turner, John A.

    2017-01-01

    Large, areal, brittle fracture of copper current collector foils was observed by 3D x-ray computed tomography (XCT) of a spherically indented Li-ion cell. This fracture was hidden and non-catastrophic to a degree because the graphite layers deformed plastically, and held the materials together so that the cracks in the foils could not be seen under optical and electron microscopy. 3D XCT on the indented cell showed “mud cracks” within the copper layer. The cracking of copper foils could not be immediately confirmed when the cell was opened for post-mortem examination. However, an X-ray radiograph on a single foil of the Cu anode showed clearly that the copper foil had broken into multiple pieces similar to the brittle cracking of a ceramic under indentation. This new failure mode of anodes on Li-ion cell has very important implications on the behavior of Li-ion cells under mechanical abuse conditions. Furthermore, the fragmentation of current collectors in the anode must be taken into consideration for the electrochemical responses which may lead to capacity loss and affect thermal runaway behavior of the cells.

  6. Proton ring trapping in a gated magnetic mirror

    International Nuclear Information System (INIS)

    Pedrow, P.D.; Greenly, J.B.; Hammer, D.A.; Sudan, R.N.

    1985-01-01

    An axis-encircling proton ring has been trapped for times (roughly-equal4 μs) much longer than the ion cyclotron period (roughly-equal80 ns). The rings, with mean radius 10 cm and with particle energies 15 protons during the first pass and 2 x 10 13 protons during the eighth and final pass. With a central solenoidal field of 0.8 T, the peak diamagnetism and azimuthal current density of the injected ring were typically 10 mT (100 G) and 10 A/cm 2 , respectively

  7. Overview of collective effects in the NLC main damping rings

    International Nuclear Information System (INIS)

    Wolski, A.; Santis, S. de

    2002-01-01

    The present design for the NLC Main Damping Rings (MDRs) meets the specifications for acceptance and extracted emittance, in the limit of zero current. However, the relatively large bunch charge and moderate energy mean that a variety of collective effects can impact the beam dynamics, leading to loss of stability or increase of equilibrium emittance. These effects include intrabeam scattering, impedance from numerous sources, fast ion instability, and (in the positron ring) electron cloud. In this note, we survey the expected impact on damping ring performance from each of a number of collective effects, and discuss the priorities for future studies in this area

  8. Theoretical Analysis of Potential and Current Distributions in Planar Electrodes of Lithium-ion Batteries

    International Nuclear Information System (INIS)

    Taheri, Peyman; Mansouri, Abraham; Yazdanpour, Maryam; Bahrami, Majid

    2014-01-01

    An analytical model is proposed to describe the two-dimensional distribution of potential and current in planar electrodes of pouch-type lithium-ion batteries. A concentration-independent polarization expression, obtained experimentally, is used to mimic the electrochemical performance of the battery. By numerically solving the charge balance equation on each electrode in conjugation with the polarization expression, the battery behavior during constant-current discharge processes is simulated. Our numerical simulations show that reaction current between the electrodes remains approximately uniform during most of the discharge process, in particular, when depth-of-discharge varies from 5% to 85%. This observation suggests to simplify the electrochemical behavior of the battery such that the charge balance equation on each electrode can be solved analytically to obtain closed-form solutions for potential and current density distributions. The analytical model shows fair agreement with numerical data at modest computational cost. The model is applicable for both charge and discharge processes, and its application is demonstrated for a prismatic 20 Ah nickel-manganese-cobalt lithium-ion battery during discharge processes

  9. Manipulation of high-current pulses for heavy-ion fusion

    International Nuclear Information System (INIS)

    Sharp, W.M.; Callahan, D.A.; Griedman, A.; Grote, D.P.

    1996-01-01

    For efficient induction-driven heavy-ion fusion, the current profile along a pulse must be modified in a non-selfsimilar manner between the accelerator and the target. In the accelerator, the pulse should have a duration of at least 50 ns in order to make efficient use of the induction cores, and the current should by nearly uniform along the pulse to minimize the aperture. In contrast, the optimal current profile on target consists of a main pulse of about 10 ns preceded by a longer low-current 'foot.' This pulse-shape manipulation must be carried out at the final pulse energy (5-10 GeV for 200 amu ions) in the presence of a large nonlinear longitudinal space-charge field. A straightforward method is presented here for doing the required pulse shaping. Induction-ceU voltages are generated using idealized beam profiles both in the accelerator and on target, and they are verified and checked for error sensitivity using the fluid/envelope code CIRCE

  10. On Leakage Current Measured at High Cell Voltages in Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Vadivel, Nicole R.; Ha, Seungbum; He, Meinan; Dees, Dennis; Trask, Steve; Polzin, Bryant; Gallagher, Kevin G.

    2017-01-01

    In this study, parasitic side reactions in lithium-ion batteries were examined experimentally using a potentiostatic hold at high cell voltage. The experimental leakage current measured during the potentiostatic hold was compared to the Tafel expression and showed poor agreement with the expected transfer coefficient values, indicating that a more complicated expression could be needed to accurately capture the physics of this side reaction. Here we show that cross-talk between the electrodes is the primary contribution to the observed leakage current after the relaxation of concentration gradients has ceased. This cross-talk was confirmed with experiments using a lithium-ion conducting glass ceramic (LICGC) separator, which has high conductance only for lithium cations. The cells with LICGC separators showed significantly less leakage current during the potentiostatic hold test compared to cells with standard microporous separators where cross-talk is present. In addition, direct-current pulse power tests show an impedance rise for cells held at high potentials and for cells held at high temperatures, which could be attributed to film formation from the parasitic side reaction. Based on the experimental findings, a phenomenological mechanism is proposed for the parasitic side reaction which accounts for cross-talk and mass transport of the decomposition products across the separator.

  11. Black rings

    International Nuclear Information System (INIS)

    Emparan, Roberto; Reall, Harvey S

    2006-01-01

    A black ring is a five-dimensional black hole with an event horizon of topology S 1 x S 2 . We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)

  12. Storage ring group summary

    International Nuclear Information System (INIS)

    King, N.M.

    1980-01-01

    The Storage Ring Group set out to identify and pursue salient problems in accelerator physics for heavy ion fusion, divorced from any particular reference design concept. However, it became apparent that some basic parameter framework was required to correlate the different study topics. As the Workshop progressed, ring parameters were modified and updated. Consequently, the accompanying papers on individual topics will be found to refer to slightly varied parameters, according to the stage at which the different problems were tackled

  13. Effects of pioglitazone on cardiac ion currents and action potential morphology in canine ventricular myocytes.

    Science.gov (United States)

    Kistamás, Kornél; Szentandrássy, Norbert; Hegyi, Bence; Ruzsnavszky, Ferenc; Váczi, Krisztina; Bárándi, László; Horváth, Balázs; Szebeni, Andrea; Magyar, János; Bányász, Tamás; Kecskeméti, Valéria; Nánási, Péter P

    2013-06-15

    Despite its widespread therapeutical use there is little information on the cellular cardiac effects of the antidiabetic drug pioglitazone in larger mammals. In the present study, therefore, the concentration-dependent effects of pioglitazone on ion currents and action potential configuration were studied in isolated canine ventricular myocytes using standard microelectrode, conventional whole cell patch clamp, and action potential voltage clamp techniques. Pioglitazone decreased the maximum velocity of depolarization and the amplitude of phase-1 repolarization at concentrations ≥3 μM. Action potentials were shortened by pioglitazone at concentrations ≥10 μM, which effect was accompanied with significant reduction of beat-to-beat variability of action potential duration. Several transmembrane ion currents, including the transient outward K(+) current (Ito), the L-type Ca(2+) current (ICa), the rapid and slow components of the delayed rectifier K(+) current (IKr and IKs, respectively), and the inward rectifier K(+) current (IK1) were inhibited by pioglitazone under conventional voltage clamp conditions. Ito was blocked significantly at concentrations ≥3 μM, ICa, IKr, IKs at concentrations ≥10 μM, while IK1 at concentrations ≥30 μM. Suppression of Ito, ICa, IKr, and IK1 has been confirmed also under action potential voltage clamp conditions. ATP-sensitive K(+) current, when activated by lemakalim, was effectively blocked by pioglitazone. Accordingly, action potentials were prolonged by 10 μM pioglitazone when the drug was applied in the presence of lemakalim. All these effects developed rapidly and were readily reversible upon washout. In conclusion, pioglitazone seems to be a harmless agent at usual therapeutic concentrations. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source

    Energy Technology Data Exchange (ETDEWEB)

    Waldmann, Ole; Ludewigt, Bernhard [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2011-11-15

    A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm{sup 2} have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material.

  15. Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source.

    Science.gov (United States)

    Waldmann, Ole; Ludewigt, Bernhard

    2011-11-01

    A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm(2) have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material. © 2011 American Institute of Physics

  16. White Ring; White ring

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, H.; Yuzawa, H. [Nikken Sekkei Ltd., Osaka (Japan)

    1998-01-05

    White Ring is a citizen`s gymnasium used for figure skating and short track speed skating games of 18th Winter Olympic Games in 1998. White Ring is composed of a main-arena and a sub-arena. For the main-arena with an area 41mtimes66m, an ice link can be made by disengaging the potable floor and by flowing brine in the bridged polystyrene pipes embedded in the concrete floor. Due to the fortunate groundwater in this site, well water is used for the outside air treatment energy in 63% during heating and in 35% during cooling. Ammonia is used as a cooling medium for refrigerating facility. For the heating of audience area in the large space, heat load from the outside is reduced by enhancing the heat insulation performance of the roof of arena. The audience seats are locally heated using heaters. For the White Ring, high quality environment is realized for games through various functions of the large-scale roof of the large space. Success of the big event was expected. 15 figs., 4 tabs.

  17. Contribution of the backstreaming ions to the self-magnetic pinch (SMP) diode current

    Science.gov (United States)

    Mazarakis, Michael G.; Bennett, Nichelle; Cuneo, Michael E.; Fournier, Sean D.; Johnston, Mark D.; Kiefer, Mark L.; Leckbee, Joshua J.; Nielsen, Dan S.; Oliver, Bryan V.; Sceiford, Matthew E.; Simpson, Sean C.; Renk, Timothy J.; Ruiz, Carlos L.; Webb, Timothy J.; Ziska, Derek; Droemer, Darryl W.; Gignac, Raymond E.; Obregon, Robert J.; Wilkins, Frank L.; Welch, Dale R.

    2018-04-01

    The results presented here were obtained with a self-magnetic pinch (SMP) diode mounted at the front high voltage end of the RITS accelerator. RITS is a Self-Magnetically Insulated Transmission Line (MITL) voltage adder that adds the voltage pulse of six 1.3 MV inductively insulated cavities. The RITS driver together with the SMP diode has produced x-ray spots of the order of 1 mm in diameter and doses adequate for the radiographic imaging of high area density objects. Although, through the years, a number of different types of radiographic electron diodes have been utilized with SABER, HERMES III and RITS accelerators, the SMP diode appears to be the most successful and simplest diode for the radiographic investigation of various objects. Our experiments had two objectives: first to measure the contribution of the back-streaming ion currents emitted from the anode target and second to try to evaluate the energy of those ions and hence the Anode-Cathode (A-K) gap actual voltage. In any very high voltage inductive voltage adder utilizing MITLs to transmit the power to the diode load, the precise knowledge of the accelerating voltage applied on the A-K gap is problematic. This is even more difficult in an SMP diode where the A-K gap is very small (˜1 cm) and the diode region very hostile. The accelerating voltage quoted in the literature is from estimates based on the measurements of the anode and cathode currents of the MITL far upstream from the diode and utilizing the para-potential flow theories and inductive corrections. Thus, it would be interesting to have another independent measurement to evaluate the A-K voltage. The diode's anode is made of a number of high-Z metals in order to produce copious and energetic flash x-rays. It was established experimentally that the back-streaming ion currents are a strong function of the anode materials and their stage of cleanness. We have measured the back-streaming ion currents emitted from the anode and propagating

  18. A pre-heating method based on sinusoidal alternating current for lithium-ion battery

    Science.gov (United States)

    Fan, Wentao; Sun, Fengchun; Guo, Shanshan

    2018-04-01

    In this paper, a method of low temperature pre-heating of sinusoidal alternating current (SAC) is proposed. Generally, the lower the frequency of the AC current, the higher the heat generation rate. Yet at low frequency, there is a risk of lithium-ion deposition during the half cycle of charging. This study develops a temperature-adaptive, deposition-free AC pre-heating method. a equivalent electric circuit(EEC) model is established to predict the heat generation rate and temperature status, whose parameters are calibrated from the EIS impedance measurements. The effects of current frequency and amplitude on the heating effect are investigated respectively. A multistep temperature-adaptive amplitude strategy is proposed and the cell can be heated from -20°C to 5°C within 509s at 100Hz frequency with this method.

  19. Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

    International Nuclear Information System (INIS)

    Wetteland, C. J.; Field, K. G.; Gerczak, T. J.; Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R.

    2013-01-01

    The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150μA of proton current from the source, with over 70μA on the target stage. However, beam fluxes above ∼1×10 17 /m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

  20. How to resolve microsecond current fluctuations in single ion channels: The power of beta distributions

    Science.gov (United States)

    Schroeder, Indra

    2015-01-01

    Abstract A main ingredient for the understanding of structure/function correlates of ion channels is the quantitative description of single-channel gating and conductance. However, a wealth of information provided from fast current fluctuations beyond the temporal resolution of the recording system is often ignored, even though it is close to the time window accessible to molecular dynamics simulations. This kind of current fluctuations provide a special technical challenge, because individual opening/closing or blocking/unblocking events cannot be resolved, and the resulting averaging over undetected events decreases the single-channel current. Here, I briefly summarize the history of fast-current fluctuation analysis and focus on the so-called “beta distributions.” This tool exploits characteristics of current fluctuation-induced excess noise on the current amplitude histograms to reconstruct the true single-channel current and kinetic parameters. A guideline for the analysis and recent applications demonstrate that a construction of theoretical beta distributions by Markov Model simulations offers maximum flexibility as compared to analytical solutions. PMID:26368656

  1. Development of Low Level RF Control Systems for Superconducting Heavy Ion Linear Accelerators, Electron Synchrotrons and Storage Rings

    CERN Document Server

    Aminov, Bachtior; Kolesov, Sergej; Pekeler, Michael; Piel, Christian; Piel, Helmut

    2005-01-01

    Since 2001 ACCEL Instruments is supplying low level RF control systems together with turn key cavity systems. The early LLRF systems used the well established technology based on discrete analogue amplitude and phase detectors and modulators. Today analogue LLRF systems can make use of advanced vector demodulators and modulators combined with a fast computer controlled analogue feed back loop. Feed forward control is implemented to operate the RF cavity in an open loop mode or to compensate for predictable perturbations. The paper will introduce the general design philosophy and show how it can be adapted to different tasks as controlling a synchrotron booster nc RF system at 500 MHz, or superconducting storage ring RF cavities, as well as a linear accelerator at 176 MHz formed by a chain of individually driven and controlled superconducting λ/2 cavities.

  2. Electron cyclotron resonance ion source for high currents of mono- and multicharged ion and general purpose unlimited lifetime application on implantation devices

    Science.gov (United States)

    Bieth, C.; Bouly, J. L.; Curdy, J. C.; Kantas, S.; Sortais, P.; Sole, P.; Vieux-Rochaz, J. L.

    2000-02-01

    The electron cyclotron resonance (ECR) ion sources were originally developed for high energy physic applications. They are used as injectors on linear accelerators and cyclotrons to further increase the particle energy via high charge state ions. This ECR technology is well suited for sources placed on a high voltage platform where ac power available is limited by insulated transformers. The PANTECHNIK family of ion source with its wide range of ion beam (various charge states with various beam currents) offers new possibilities and perspectives in the field of ion implantation. In addition to all these possibilities, the PANTECHNIK ion sources have many other advantages like: a very long lifetime without maintenance expense, good stability, efficiency of ionization close to 100% (this improves the lifetime of the pumping system and other equipment), the possibility of producing ion beams with different energies, and a very good reproducibility. The main characteristics of sources like Nanogan or SuperNanogan will be recalled. We will especially present the results obtained with the new Microgan 10 GHz source that can be optimized for the production of high currents of monocharged ion, including reactive gas like BF3 (2 mA e of B+) or medium currents of low charge state like 0.5 mA e of Ar4+. The latest results obtained with Microgan 10 GHz show that it is possible to drive the source up to 30 mA e of total current, with an emittance of 150 π mm mrad at 40 kV and also to maintain the production of multicharged ions like Ar8+.

  3. Ion temperature anisotropy effects on threshold conditions of a shear-modified current driven electrostatic ion-acoustic instability in the topside auroral ionosphere

    Directory of Open Access Journals (Sweden)

    P. J. G. Perron

    2013-03-01

    Full Text Available Temperature anisotropies may be encountered in space plasmas when there is a preferred direction, for instance, a strong magnetic or electric field. In this paper, we study how ion temperature anisotropy can affect the threshold conditions of a shear-modified current driven electrostatic ion-acoustic (CDEIA instability. In particular, this communication focuses on instabilities in the context of topside auroral F-region situations and in the limit where finite Larmor radius corrections are small. We derived a new fluid-like expression for the critical drift which depends explicitly on ion anisotropy. More importantly, for ion to electron temperature ratios typical of F-region, solutions of the kinetic dispersion relation show that ion temperature anisotropy may significantly lower the drift threshold required for instability. In some cases, a perpendicular to parallel ion temperature ratio of 2 and may reduce the relative drift required for the onset of instability by a factor of approximately 30, assuming the ion-acoustic speed of the medium remains constant. Therefore, the ion temperature anisotropy should be considered in future studies of ion-acoustic waves and instabilities in the high-latitude ionospheric F-region.

  4. Hypotonic stimuli enhance proton-gated currents of acid-sensing ion channel-1b

    International Nuclear Information System (INIS)

    Ugawa, Shinya; Ishida, Yusuke; Ueda, Takashi; Yu, Yong; Shimada, Shoichi

    2008-01-01

    Acid-sensing ion channels (ASICs) are strong candidates for mammalian mechanoreceptors. We investigated whether mouse acid-sensing ion channel-1b (ASIC1b) is sensitive to mechanical stimuli using oocyte electrophysiology, because ASIC1b is located in the mechanosensory stereocilia of cochlear hair cells. Hypotonic stimuli that induced membrane stretch of oocytes evoked no significant current in ASIC1b-expressing oocytes at pH 7.5. However, acid (pH 4.0 or 5.0)-evoked currents in the oocytes were substantially enhanced by the hypotonicity, showing mechanosensitivity of ASIC1b and possible mechanogating of the channel in the presence of other components. Interestingly, the ASIC1b channel was permeable to K + (a principal charge carrier for cochlear sensory transduction) and the affinity of the channel for amiloride (IC 50 (inhibition constant) = approximately 48.3 μM) was quite similar to that described for the mouse hair cell mechanotransducer current. Taken together, these data raise the possibility that ASIC1b participates in cochlear mechanoelectrical transduction

  5. Singularities of current-voltage characteristics of GaAs films fabricated by pulsed ions ablation

    International Nuclear Information System (INIS)

    Kabyshev, A.V.; Konusov, F.V.; Lozhnikov, S.N.; Remnev, G.E.; Saltymakov, M.S.

    2009-01-01

    A singularities and advantages of the optical, photoelectric and electrical properties of GaAs in comparison with other available materials for electronics, for example, silicon allow to manufacture on it base the devices having an advanced characteristics. The GaAs for electronics, obtained from the dense ablation plasma, possess some preferences as compared to material manufactured by traditional methods of vacuum deposition. The electrical characteristics of GaAs produced by chemical deposition were extensively studied. Purpose of this work is investigation the current-voltage characteristics of thin films of GaAs, deposited on polycrystalline corundum (polycor) from plasma forming the power ions bunch and determination of the thermal vacuum annealing effect on photoelectric and electrical properties of films. Peculiarities of optical, photoelectric and current-voltage characteristics of films obtained by ions ablation are determined by deposition conditions and resistance of initial target GaAs. The transitions between the states with low- and high conduction were revealed directly after deposition in films having the optical properties similar to amorphous materials and/or after annealing in films with properties similar to initial target GaAs. Behavior of current-voltage characteristics at vacuum annealing correlates with Schottky barrier height and photosensitivity and is accompanies of the transport mechanism change. The stable properties of films are formed at its dark conduction 10 -10 -10 -8 s and after annealing at T an =600-700 K. (authors)

  6. Subattoampere current induced by single ions in silicon oxide layers of nonvolatile memory cells

    International Nuclear Information System (INIS)

    Cellere, G.; Paccagnella, A.; Larcher, L.; Visconti, A.; Bonanomi, M.

    2006-01-01

    A single ion impinging on a thin silicon dioxide layer generates a number of electron/hole pairs proportional to its linear energy transfer coefficient. Defects generated by recombination can act as a conductive path for electrons that cross the oxide barrier, thanks to a multitrap-assisted mechanism. We present data on the dependence of this phenomenon on the oxide thickness by using floating gate memory arrays. The tiny number of excess electrons stored in these devices allows for extremely high sensitivity, impossible with any direct measurement of oxide leakage current. Results are of particular interest for next generation devices

  7. Impurity mapping in sulphide minerals using Time-resolved Ion Beam Induced Current imaging

    International Nuclear Information System (INIS)

    Laird, Jamie S.; Johnson, Brett C.; Ganesan, Kumaravelu; Kandasamy, Sasikaran; Davidson, Garry; Borg, Stacey; Ryan, Chris G.

    2010-01-01

    The semiconducting properties and charge transport within natural minerals like pyrite are postulated to drive certain geochemical processes which can lead to precious metal ore genesis. In this paper we outline electrical measurements on mineral samples and present spatio-temporally resolved Ion Beam Induced Charge or Current studies on a Schottky pyrite junction. Au-Schottky contacts were fabricated in regions selected by thermoelectric and 4-point probe resistivity measurements. The complexity in charge transport due to impurity variations results in imaging contrast which is deemed important for fluid electrochemistry. The relevance of understanding charge collection in pyrite in the context of complex geochemical processes is briefly discussed.

  8. Ion transfer through solvent polymeric membranes driven by an exponential current flux.

    Science.gov (United States)

    Molina, A; Torralba, E; González, J; Serna, C; Ortuño, J A

    2011-03-21

    General analytical equations which govern ion transfer through liquid membranes with one and two polarized interfaces driven by an exponential current flux are derived. Expressions for the transient and stationary E-t, dt/dE-E and dI/dE-E curves are obtained, and the evolution from transient to steady behaviour has been analyzed in depth. We have also shown mathematically that the voltammetric and stationary chronopotentiometric I(N)-E curves are identical (with E being the applied potential for voltammetric techniques and the measured potential for chronopotentiometric techniques), and hence, their derivatives provide identical information.

  9. A note on the ring current in Saturn’s magnetosphere: Comparison of magnetic data obtained during the Pioneer-11 and Voyager-1 and -2 fly-bys

    Directory of Open Access Journals (Sweden)

    E. J. Bunce

    2003-03-01

    Full Text Available We examine the residual (measured minus internal magnetic field vectors observed in Saturn’s magnetosphere during the Pioneer-11 fly-by in 1979, and compare them with those observed during the Voyager-1 and -2 fly-bys in 1980 and 1981. We show for the first time that a ring current system was present within the magnetosphere during the Pioneer-11 encounter, which was qualitatively similar to those present during the Voyager fly-bys. The analysis also shows, however, that the ring current was located closer to the planet during the Pioneer-11 encounter than during the comparable Voyager-1 fly-by, reflecting the more com-pressed nature of the magnetosphere at the time. The residual field vectors have been fit using an adaptation of the current system proposed for Jupiter by Connerney et al. (1981a. A model that provides a reasonably good fit to the Pioneer-11 Saturn data extends radially between 6.5 and 12.5 RS (compared with a noon-sector magnetopause distance of 17 RS, has a north-south extent of 4 RS, and carries a total current of 9.6 MA. A corresponding model that provides a qualitatively similar fit to the Voyager data, determined previously by Connerney et al. (1983, extends radially between 8 and 15.5 RS (compared with a noon-sector magnetopause distance for Voyager-1 of 23–24 RS, has a north-south extent of 6 RS, and carries a total current of 11.5 MA.Key words. Magnetospheric physics (current systems, magnetospheric configuration and dynamics, planetary magnetospheres

  10. Parameters affecting profile shape of a high energy low current thin ion beam. Vol. 2

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Salam, F W; Moustafa, O A; El-Khabeary, H [Accelerators Department, Nuclear Research Center, Atomic Energy Authority, Cairo, (Egypt)

    1996-03-01

    The shape of the profile of a high energy, low current beam of finite length has beam investigated. The beam profile shape depends on the initial beam radius, beam perveance, atomic mass number, charge state of ions, and beam length. These parameters can affect the relation between the initial beam radius and the corresponding final one. An optimum initial beam radius corresponding to minimum final beam at the target has been formulated and the relation between them is deduced taking account of the space charge effect. The minimum beam radius at the target was found to be equal to 2.3 of the optimum initial radius. It is concluded that in order to obtain a small beam radius at a target placed at a finite distance from an ion source, a beam of a low perveance, low atomic mass number and high number of electronic charge is required. This is an important detection for micro machining applications using the oscillating electron ion source which produces nearly paraxial thin beam of low perveance. 12 figs.

  11. Temperature dependent capacity contribution of thermally treated anode current collectors in lithium ion batteries

    International Nuclear Information System (INIS)

    Kim, Tae Kwon; Li Xifei; Wang Chunlei

    2013-01-01

    Highlights: ► We studied the influence of the thermal treatment of current collectors on the energy capacity. ► Different current collectors show different thermal treatment effect on performance. ► The non-negligible capacity contribution is closely related to the treatment temperatures. ► Our results could be beneficial to designing battery architectures. - Abstract: Metal current collectors, offering a good connection between the active materials and the external circuit, is an important component in a rechargeable lithium ion battery. Some necessary thermal treatment in the battery fabrication and assembly procedure results in current collectors with some non-negligible reversible energy capacities; however, these energy capacities were negligible in the previous references. In this research, for the first time, we investigated the influence of the thermal treatment of current collectors (such as copper foil and stainless steel disk) on energy capacities. Our results indicate that different current collector materials have different thermal treatment effects on their electrochemical performance. The non-negligible capacity contribution is closely related to the treatment temperature.

  12. Electrostatic storage rings for atomic and molecular physics

    International Nuclear Information System (INIS)

    Schmidt, H T

    2015-01-01

    A significant number of electrostatic ion-storage rings have been built since the late 1990s or are currently in their construction or commisioning phases. In this short contribution, we attempt to supply an overview of these different facilities, while we also mention a selection of the electrostatic ion-beam traps that has been developed through the same time period and by some of the same research groups. (paper)

  13. EBT ring physics

    International Nuclear Information System (INIS)

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers

  14. Comments on the current status and possible future directions of research on heavy-ion interactions near the Coulomb barrier

    International Nuclear Information System (INIS)

    Satchler, G.R.

    1990-01-01

    This paper contains comments on the current status and possible future directions of research on heavy-ion interactions near the Coulomb barrier. Fusion reactions, elastic and inelastic scattering and transfer reactions are discussed

  15. Metal current collector-free freestanding silicon–carbon 1D nanocomposites for ultralight anodes in lithium ion batteries

    KAUST Repository

    Choi, Jang Wook; Hu, Liangbing; Cui, Lifeng; McDonough, James R.; Cui, Yi

    2010-01-01

    Although current collectors take up more weight than active materials in most lithium ion battery cells, so far research has been focused mainly on improving gravimetric capacities of active materials. To address this issue of improving gravimetric

  16. Beam position and total current monitor for heavy ion fusion beams

    International Nuclear Information System (INIS)

    Berners, D.; Reginato, L.L.

    1992-10-01

    Heavy Ion Fusion requires moderate currents, 1-10A, for a duration of about 1 μs. For accurate beam transport, the center of charge must be located to within ± 100 μm. Beam position and intensity may be excited at frequencies approaching 10 MHz, and the monitoring system must have adequate bandwidth to respond at these frequencies. We have modified the Rogowski technique by using distributed reactance multiturn magnetic loops so that it is suitable for measuring current position as well as amplitude. Four identical stripline coils are wound one per quadrant around a non magnetic core. The sensitivity is similar to that of a lumped coil system, with the added advantage of increased bandwidth. The voltages induced on the four separate coils are compared and suitable signal conditioning is performed to recover beam position and intensity information

  17. Two dimensional code for modeling of high ione cyclotron harmonic fast wave heating and current drive

    International Nuclear Information System (INIS)

    Grekov, D.; Kasilov, S.; Kernbichler, W.

    2016-01-01

    A two dimensional numerical code for computation of the electromagnetic field of a fast magnetosonic wave in a tokamak at high harmonics of the ion cyclotron frequency has been developed. The code computes the finite difference solution of Maxwell equations for separate toroidal harmonics making use of the toroidal symmetry of tokamak plasmas. The proper boundary conditions are prescribed at the realistic tokamak vessel. The currents in the RF antenna are specified externally and then used in Ampere law. The main poloidal tokamak magnetic field and the ''kinetic'' part of the dielectric permeability tensor are treated iteratively. The code has been verified against known analytical solutions and first calculations of current drive in the spherical torus are presented.

  18. Ion cyclotron and lower hybrid arrays applicable to current drive in fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Bosia, G.; Ragona, R. [Department of Physics, Università di Torino (Italy); Helou, W.; Goniche, M.; Hillaret, J. [CEA/DSM/IRFM F-13 108 St Paul Les Durance (France)

    2014-02-12

    This paper presents concepts for Ion Cyclotron and Lower Hybrid Current Drive arrays applicable to fusion reactors and based on periodically loaded line power division. It is shown that, in large arrays, such as the ones proposed for fusion reactor applications, these schemes can offer, in principle, a number of practical advantages, compared with currently adopted ones, such as in-blanket operation at significantly reduced power density, lay out suitable for water cooling, single ended or balanced power feed, simple and load independent impedance matching In addition, a remote and accurate real time measurement of the complex impedance of all array elements as well as detection, location, and measurement of the complex admittance of a single arc occurring anywhere in the structure is possible.

  19. Revisiting the Corrosion of the Aluminum Current Collector in Lithium-Ion Batteries.

    Science.gov (United States)

    Ma, Tianyuan; Xu, Gui-Liang; Li, Yan; Wang, Li; He, Xiangming; Zheng, Jianming; Liu, Jun; Engelhard, Mark H; Zapol, Peter; Curtiss, Larry A; Jorne, Jacob; Amine, Khalil; Chen, Zonghai

    2017-03-02

    The corrosion of aluminum current collectors and the oxidation of solvents at a relatively high potential have been widely investigated with an aim to stabilize the electrochemical performance of lithium-ion batteries using such components. The corrosion behavior of aluminum current collectors was revisited using a home-build high-precision electrochemical measurement system, and the impact of electrolyte components and the surface protection layer on aluminum foil was systematically studied. The electrochemical results showed that the corrosion of aluminum foil was triggered by the electrochemical oxidation of solvent molecules, like ethylene carbonate, at a relative high potential. The organic radical cations generated from the electrochemical oxidation are energetically unstable and readily undergo a deprotonation reaction that generates protons and promotes the dissolution of Al 3+ from the aluminum foil. This new reaction mechanism can also shed light on the dissolution of transitional metal at high potentials.

  20. In situ beam angle measurement in a multi-wafer high current ion implanter

    International Nuclear Information System (INIS)

    Freer, B.S.; Reece, R.N.; Graf, M.A.; Parrill, T.; Polner, D.

    2005-01-01

    Direct, in situ measurement of the average angle and angular content of an ion beam in a multi-wafer ion implanter is reported for the first time. A new type of structure and method are described. The structures are located on the spinning disk, allowing precise angular alignment to the wafers. Current that passes through the structures is known to be within a range of angles and is detected behind the disk. By varying the angle of the disk around two axes, beam current versus angle is mapped and the average angle and angular spread are calculated. The average angle measured in this way is found to be consistent with that obtained by other techniques, including beam centroid offset and wafer channeling methods. Average angle of low energy beams, for which it is difficult to use other direct methods, is explored. A 'pencil beam' system is shown to give average angle repeatability of 0.13 deg. (1σ) or less, for two low energy beams under normal tuning variations, even though no effort was made to control the angle