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Sample records for negative hydrogen ions

  1. Negative hydrogen ion production mechanisms

    SciTech Connect

    Bacal, M.; Wada, M.

    2015-06-15

    Negative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed.

  2. Negative-hydrogen-ion sources

    SciTech Connect

    Prelec, K.

    1983-01-01

    There are two main areas of negative hydrogen ion applications: injection into high energy accelerators and production of beams of energetic hydrogen atoms for fusion devices. In both cases, the ease with which the charge state of negative ions can be changed by either single or double electron stripping is the reason that made their application attractive. In tandem accelerators, the final energy of H/sup +/ ions is twice as high as it would correspond to the terminal voltage, in circular accelerators (synchrotrons, storage rings) injection of H/sup +/ ions by full stripping of H/sup -/ ions in a foil inside the ring is not limited by the Liouville's theorem and results in a higher phase space density than achieved by direct H/sup +/ injection. Finally, beams of hydrogen atoms at energies above 100 keV, which will be required for plasma heating and current drive in future fusion devices, can efficiently be produced only by acceleration of negative ions and their subsequent neutralization.

  3. An advanced negative hydrogen ion source.

    PubMed

    Goncharov, Alexey A; Dobrovolsky, Andrey N; Goretskii, Victor P

    2016-02-01

    The results of investigation of emission productivity of negative particles source with cesiated combined discharge are presented. A cylindrical beam of negative hydrogen ions with density about 2 A/cm(2) in low noise mode on source emission aperture is obtained. The total beam current values are up to 200 mA for negative hydrogen ions and up to 1.5 A for all negative particles with high divergence after source. The source has simple design and can produce stable discharge with low level of oscillation. PMID:26931996

  4. Negative hydrogen ion yields at plasma grid surface in a negative hydrogen ion source

    SciTech Connect

    Wada, M.; Kenmotsu, T.; Sasao, M.

    2015-04-08

    Negative hydrogen (H{sup −}) ion yield from the plasma grid due to incident hydrogen ions and neutrals has been evaluated with the surface collision cascade model, ACAT (Atomic Collision in Amorphous Target) coupled to a negative surface ionization models. Dependence of negative ion fractions upon the velocity component normal to the surface largely affect the calculation results of the final energy and angular distributions of the H{sup −} ions. The influence is particularly large for H{sup −} ions desorbed from the surface due to less than several eV hydrogen particle implact. The present calculation predicts that H{sup −} ion yield can be maximized by setting the incident angle of hydrogen ions and neutrals to be 65 degree. The Cs thickness on the plasma grid should also affect the yields and mean energies of surface produced H{sup −} ions by back scattering and ion induced desorption processes.

  5. Negative ion extraction from hydrogen plasma bulk

    SciTech Connect

    Oudini, N.; Taccogna, F.; Minelli, P.

    2013-10-15

    A two-dimensional particle-in-cell/Monte Carlo collision model has been developed and used to study low electronegative magnetized hydrogen plasma. A configuration characterized by four electrodes is used: the left electrode is biased at V{sub l} = −100 V, the right electrode is grounded, while the upper and lower transversal electrodes are biased at an intermediate voltage V{sub ud} between 0 and −100 V. A constant and homogeneous magnetic field is applied parallel to the lateral (left/right) electrodes. It is shown that in the magnetized case, the bulk plasma potential is close to the transversal electrodes bias inducing then a reversed sheath in front of the right electrode. The potential drop within the reversed sheath is controlled by the transversal electrodes bias allowing extraction of negative ions with a significant reduction of co-extracted electron current. Furthermore, introducing plasma electrodes, between the transversal electrodes and the right electrode, biased with a voltage just above the plasma bulk potential, increases the negative ion extracted current and decreases significantly the co-extracted electron current. The physical mechanism on basis of this phenomenon has been discussed.

  6. Production of negative hydrogen ions on metal grids

    SciTech Connect

    Oohara, W.; Maetani, Y.; Takeda, Takashi; Takeda, Toshiaki; Yokoyama, H.; Kawata, K.

    2015-03-15

    Negative hydrogen ions are produced on a nickel grid with positive-ion irradiation. In order to investigate the production mechanism, a copper grid without the chemisorption of hydrogen atoms and positive helium ions without negative ionization are used for comparison. Positive hydrogen ions reflected on the metal surface obtain two electrons from the surface and become negatively ionized. It is found that the production yield of negative ions by desorption ionization of chemisorbed hydrogen atoms seems to be small, and the production is a minor mechanism.

  7. Production of negative hydrogen ions on metal grids

    NASA Astrophysics Data System (ADS)

    Oohara, W.; Maetani, Y.; Takeda, Takashi; Takeda, Toshiaki; Yokoyama, H.; Kawata, K.

    2015-03-01

    Negative hydrogen ions are produced on a nickel grid with positive-ion irradiation. In order to investigate the production mechanism, a copper grid without the chemisorption of hydrogen atoms and positive helium ions without negative ionization are used for comparison. Positive hydrogen ions reflected on the metal surface obtain two electrons from the surface and become negatively ionized. It is found that the production yield of negative ions by desorption ionization of chemisorbed hydrogen atoms seems to be small, and the production is a minor mechanism.

  8. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results. PMID:26932087

  9. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.

  10. Negative ion yields in hydrogen scattering from graphite surfaces

    SciTech Connect

    Gleeson, M. A.; Koppers, W. R.; Kleyn, A. W.; Tsumori, K.

    1998-08-20

    We compare the negative ion fraction obtained for scattering of hydrogenous ions (H{sub x}{sup +}, x=1-3) from highly oriented pyrolytic graphite (HOPG), with that obtained for scattering from a polycrystalline graphite surface. In contrast to the HOPG surface, which has a negative ion yield of the order of 1-2%, the polycrystalline sample has yields of up to 30%.

  11. Electron Transport across Magnetic Filter in Negative Hydrogen Ion Source

    NASA Astrophysics Data System (ADS)

    Fukano, Azusa; Ogasawara, Masatada

    2001-12-01

    Profiles of electron temperature and number density in a negative-ion source are investigated theoretically. Spatial dependence over the magnetic filter region is obtained using the equations of electron flux and electron heat flux that include the effect of interference of forces by the density gradient and temperature gradient. Due to the effect of the magnetic filter, temperature and density of the electron decrease from the source chamber to the extraction chamber, and the decrease depends on the magnitude of the magnetic flux. The effect of the magnetic filter on the production and destruction rates of the negative hydrogen ion is examined. The reaction rate for the dissociative attachment reaction which produces the negative hydrogen ion increases with the decrease of the electron temperature. However, the production rate per one vibrationally excited hydrogen molecule decreases with the decrease of electron density. On the other hand, the destruction probability of the negative ion by the electron detachment reaction decreases significantly by the decrease of the electron density and temperature. The magnetic filter does not enhance the production of the negative hydrogen ion, but it reduces the destruction of the negative ion because of the decrease of the electron density.

  12. Cesium in hydrogen negative-ion sources

    SciTech Connect

    Belchenko, Yu.I.; Davydenko, V.I.

    2006-03-15

    Experimental data on the dynamics of cesium particles in the pulsed magnetron and Penning surface-plasma ion sources are presented. Cesium escape from the source emission apertures and the cesium ion current to discharge electrodes was measured. The low value of cesium flux from the source was detected. An intense cesium ion current to the cathode (up to 0.8 A/cm{sup 2}) was measured. The high value of cesium ion current to surface-plasma source cathode confirms the cesium circulation near the cathode.

  13. Negative hydrogen ion sources for accelerators

    SciTech Connect

    Moehs, D.P.; Peters, J.; Sherman, J.; /Los Alamos

    2005-08-01

    A variety of H{sup -} ion sources are in use at accelerator laboratories around the world. A list of these ion sources includes surface plasma sources with magnetron, Penning and surface converter geometries as well as magnetic-multipole volume sources with and without cesium. Just as varied is the means of igniting and maintaining magnetically confined plasmas. Hot and cold cathodes, radio frequency, and microwave power are all in use, as well as electron tandem source ignition. The extraction systems of accelerator H{sup -} ion sources are highly specialized utilizing magnetic and electric fields in their low energy beam transport systems to produce direct current, as well as pulsed and/or chopped beams with a variety of time structures. Within this paper, specific ion sources utilized at accelerator laboratories shall be reviewed along with the physics of surface and volume H{sup -} production in regard to source emittance. Current research trends including aperture modeling, thermal modeling, surface conditioning, and laser diagnostics will also be discussed.

  14. Negative hydrogen ion source for TOKAMAK neutral beam injector (invited)

    NASA Astrophysics Data System (ADS)

    Okumura, Y.; Fujiwara, Y.; Kashiwagi, M.; Kitagawa, T.; Miyamoto, K.; Morishita, T.; Hanada, M.; Takayanagi, T.; Taniguchi, M.; Watanabe, K.

    2000-02-01

    Intense negative ion source producing multimegawatt hydrogen/deuterium negative ion beams has been developed for the neutral beam injector (NBI) in TOKAMAK thermonuclear fusion machines. Negative ions are produced in a cesium seeded multi-cusp plasma generator via volume and surface processes, and accelerated with a multistage electrostatic accelerator. The negative ion source for JT-60U has produced 18.5 A/360 keV (6.7 MW) H- and 14.3 A/380 keV (5.4 MW) D- ion beams at average current densities of 11 mA/cm2 (H-) and 8.5 mA/cm2 (D-). A high energy negative ion source has been developed for the next generation TOKAMAK such as the International Thermonuclear Experimental Reactor (ITER). The source has demonstrated to accelerate negative ions up to 1 MeV, the energy required for ITER. Higher negative ion current density of more than 20 mA/cm2 was obtained in the ITER concept sources. It was confirmed that the consumption rate of cesium is small enough to operate the source for a half year in ITER-NBI without maintenance.

  15. A future, intense source of negative hydrogen ions

    NASA Technical Reports Server (NTRS)

    Siefken, Hugh; Stein, Charles

    1994-01-01

    By directly heating lithium hydride in a vacuum, up to 18 micro-A/sq cm of negative hydrogen has been obtained from the crystal lattice. The amount of ion current extracted and analyzed is closely related to the temperature of the sample and to the rate at which the temperature is changed. The ion current appears to be emission limited and saturates with extraction voltage. For a fixed extraction voltage, the ion current could be maximized by placing a grid between the sample surface and the extraction electrode. Electrons accompanying the negative ions were removed by a magnetic trap. A Wein velocity filter was designed and built to provide definitive mass analysis of the extracted ion species. This technique when applied to other alkali hydrides may produce even higher intensity beams possessing low values of emittance.

  16. Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of cold negative ions

    DOEpatents

    Hershcovitch, A.

    1984-02-13

    A process for selectively neutralizing H/sup -/ ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H/sup -/ ions that are

  17. Cavity Ring-Down System for Density Measurement of Negative Hydrogen Ion on Negative Ion Source

    SciTech Connect

    Nakano, Haruhisa; Tsumori, Katsuyoshi; Nagaoka, Kenichi; Shibuya, Masayuki; Kisaki, Masashi; Ikeda, Katsunori; Osakabe, Masaki; Kaneko, Osamu; Asano, Eiji; Kondo, Tomoki; Sato, Mamoru; Komada, Seiji; Sekiguchi, Haruo; Takeiri, Yasuhiko; Fantz, Ursel

    2011-09-26

    A Cavity Ring-Down (CRD) system was applied to measure the density of negative hydrogen ion (H{sup -}) in vicinity of extraction surface in the H{sup -} source for the development of neutral beam injector on Large Helical Device (LHD). The density measurement with sampling time of 50 ms was carried out. The measured density with the CRD system is relatively good agreement with the density evaluated from extracted beam-current with applying a similar relation of positive ion sources. In cesium seeded into ion-source plasma, the linearity between an arc power of the discharge and the measured density with the CRD system was observed. Additionally, the measured density was proportional to the extracted beam current. These characteristics indicate the CRD system worked well for H{sup -} density measurement in the region of H{sup -} and extraction.

  18. Negative hydrogen ion production in a helicon plasma source

    SciTech Connect

    Santoso, J. Corr, C. S.; Manoharan, R.; O'Byrne, S.

    2015-09-15

    In order to develop very high energy (>1 MeV) neutral beam injection systems for applications, such as plasma heating in fusion devices, it is necessary first to develop high throughput negative ion sources. For the ITER reference source, this will be realised using caesiated inductively coupled plasma devices, containing either hydrogen or deuterium discharges, operated with high rf input powers (up to 90 kW per driver). It has been suggested that due to their high power coupling efficiency, helicon devices may be able to reduce power requirements and potentially obviate the need for caesiation due to the high plasma densities achievable. Here, we present measurements of negative ion densities in a hydrogen discharge produced by a helicon device, with externally applied DC magnetic fields ranging from 0 to 8.5 mT at 5 and 10 mTorr fill pressures. These measurements were taken in the magnetised plasma interaction experiment at the Australian National University and were performed using the probe-based laser photodetachment technique, modified for the use in the afterglow of the plasma discharge. A peak in the electron density is observed at ∼3 mT and is correlated with changes in the rf power transfer efficiency. With increasing magnetic field, an increase in the negative ion fraction from 0.04 to 0.10 and negative ion densities from 8 × 10{sup 14 }m{sup −3} to 7 × 10{sup 15 }m{sup −3} is observed. It is also shown that the negative ion densities can be increased by a factor of 8 with the application of an external DC magnetic field.

  19. Production of negative hydrogen and deuterium ions in microwave-driven ion sources.

    SciTech Connect

    Spence, D.

    1998-09-11

    The authors report progress they have made in the production of negative hydrogen and deuterium atomic ions in magnetically-confined microwave-driven (2.45 GHz) ion sources. The influence of source surface material, microwave power, source gas pressure and magnetic field configuration on the resulting ion current is discussed. Results strongly suggest that, at least in the source, vibrationally excited molecular hydrogen, the precursor to atomic negative ion production, is produced via a surface mechanism suggested by Hall et al. rather than via a gas phase reaction as is generally believed to be the case in most ion sources.

  20. Contribution of wall material to the vibrational excitation and negative ion formation in hydrogen negative ion sources (invited)

    NASA Astrophysics Data System (ADS)

    Bacal, M.; Ivanov, A. A.; Glass-Maujean, M.; Matsumoto, Y.; Nishiura, M.; Sasao, M.; Wada, M.

    2004-05-01

    The wall production contribution to the negative hydrogen ion formation in multicusp ion sources has been investigated using the photodetachment diagnostic (for determining the negative ion density and temperature), negative ion and electron extraction, and vacuum ultraviolet (VUV) emission spectroscopy. The wall material was modified either by depositing thin films from filaments made of different material or by depositing fresh material of the same filament. Thus we show that a fresh tantalum film leads to enhanced negative ion density and enhanced temperature of the hot negative ion population. The slow poisoning effect due to argon additive also indicates the presence of the wall contribution to H- formation. The study of the VUV spectra with different wall materials indicates the presence of vibrationally excited states of H2.

  1. Experimental studies of the Negative Ion of Hydrogen. Final Report

    SciTech Connect

    Bryant, Howard C.

    1999-06-30

    This document presents an overview of the results of the DOE'S support of experimental research into the structure and interactions of the negative ion of hydrogen conducted by the Department of Physics and Astronomy of the University of New Mexico at the Los Alamos National Laboratory. The work involves many collaborations with scientists from both institutions, as well as others. Although official DOE support for this work began in 1977, the experiment that led to it was done in 1971, near the time the 800 MeV linear accelerator at Los Alamos (LAMPF) first came on line. Until the mid nineties, the work was performed using the relativistic beam at LAMFF. The most recent results were obtained using the 35 keV injector beam for the Ground Test Accelerator at Los Alamos. A list of all published results from this work is presented.

  2. Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of negative ions

    DOEpatents

    Hershcovitch, Ady

    1987-01-01

    A process for selectively neutralizing H.sup.- ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H.sup.- ions that are intersected by a beam of laser light. Photodetachment is effected in a uniform magnetic field that is provided around the beam of H.sup.- ions to spin polarize the H.sup.- ions and produce first and second populations or groups of ions, having their respective proton spin aligned either with the magnetic field or opposite to it. The intersecting beam of laser light is directed to selectively neutralize a majority of the ions in only one population, or given spin polarized group of H.sup.- ions, without neutralizing the ions in the other group thereby forming a population of H.sup.- ions each of which has its proton spin down, and a second group or population of H.sup.o atoms having proton spin up. Finally, the two groups of ions are separated from each other by magnetically bending the group of H.sup.- ions away from the group of neutralized ions, thereby to form an intense H.sup.- ion beam that is directed toward a predetermined objective.

  3. Size scaling of negative hydrogen ion sources for fusion

    NASA Astrophysics Data System (ADS)

    Fantz, U.; Franzen, P.; Kraus, W.; Schiesko, L.; Wimmer, C.; Wünderlich, D.

    2015-04-01

    The RF-driven negative hydrogen ion source (H-, D-) for the international fusion experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operation at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operation at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operational issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operation down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma grid is sufficient to reduce the electron temperature below the target value of 1 eV and to reduce together with the bias applied between the differently shaped bias plate and the plasma grid the amount of co-extracted electrons. An asymmetry of the co-extracted electron currents in the two grid segments is measured, varying strongly with filter field and bias. Contrary to the prototype source, a dedicated plasma drift in vertical direction is not observed. As in the prototype source, the performance in deuterium is limited by the amount of co-extracted electrons in short as well as in long pulse operation. Caesium conditioning is much harder in deuterium than in hydrogen for which fast and reproducible conditioning is achieved. First estimates reveal a caesium consumption comparable to the one in the prototype source despite the large size.

  4. Volume Production of Negative Hydrogen and Deuterium Ions in aReflex-Type Ion Source

    SciTech Connect

    Jimbo, K.; Ehlers, K.W.; Leung, K.N.; Pyle, R.V.

    1986-01-01

    The extraction of negative and positive hydrogen and deuterium ions from a reflex-type negative ion source has been investigated. Extracted positive and negative ion currents were measured as functions of the gas flow rate, the axial magnetic field, and the bias potential of the cylindrical wall of the arc-chamber. By biasing the cylindrical wall several volts negative relative to the anode, a maximum H{sup -} current of 9.7 mA(J{sup -} {approx_equal} 100 mA/cm{sup 2}) and D{sup -} current of 4.1 mA (J{sup -} {approx_equal} 42 mA/cm{sup 2})were obtained in steady state operation. This result shows a factor of two improvement over previous data. The total impurity negative ion content was less than 1%. When the source was arranged for positive ion extraction, a high proton ratio (90%) was observed. The extracted negative ion current was approximately as large as the positive ion current.

  5. Negative hydrogen ion beam extraction from an AC heated cathode driven Bernas-type ion source

    SciTech Connect

    Okano, Y.; Miyamoto, N.; Kasuya, T.; Wada, M.

    2015-04-08

    A plasma grid structure was installed to a Bernas-type ion source used for ion implantation equipment. A negative hydrogen (H{sup −}) ion beam was extracted by an AC driven ion source by adjusting the bias to the plasma grid. The extracted electron current was reduced by positively biasing the plasma grid, while an optimum plasma grid bias voltage for negative ion beam extraction was found to be positive 3 V with respect to the arc chamber. Source operations with AC cathode heating show extraction characteristics almost identical to that with DC cathode heating, except a minute increase in H{sup −} current at higher frequency of cathode heating current.

  6. Effects of discharge chamber length on the negative ion generation in volume-produced negative hydrogen ion source

    SciTech Connect

    Chung, Kyoung-Jae; Jung, Bong-Ki; An, YoungHwa; Dang, Jeong-Jeung; Hwang, Y. S.

    2014-02-15

    In a volume-produced negative hydrogen ion source, control of electron temperature is essential due to its close correlation with the generation of highly vibrationally excited hydrogen molecules in the heating region as well as the generation of negative hydrogen ions by dissociative attachment in the extraction region. In this study, geometric effects of the cylindrical discharge chamber on negative ion generation via electron temperature changes are investigated in two discharge chambers with different lengths of 7.5 cm and 11 cm. Measurements with a radio-frequency-compensated Langmuir probe show that the electron temperature in the heating region is significantly increased by reducing the length of the discharge chamber due to the reduced effective plasma size. A particle balance model which is modified to consider the effects of discharge chamber configuration on the plasma parameters explains the variation of the electron temperature with the chamber geometry and gas pressure quite well. Accordingly, H{sup −} ion density measurement with laser photo-detachment in the short chamber shows a few times increase compared to the longer one at the same heating power depending on gas pressure. However, the increase drops significantly as operating gas pressure decreases, indicating increased electron temperatures in the extraction region degrade dissociative attachment significantly especially in the low pressure regime. It is concluded that the increase of electron temperature by adjusting the discharge chamber geometry is efficient to increase H{sup −} ion production as long as low electron temperatures are maintained in the extraction region in volume-produced negative hydrogen ion sources.

  7. Size scaling of negative hydrogen ion sources for fusion

    SciTech Connect

    Fantz, U. Franzen, P.; Kraus, W.; Schiesko, L.; Wimmer, C.; Wünderlich, D.

    2015-04-08

    The RF-driven negative hydrogen ion source (H{sup −}, D{sup −}) for the international fusion experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operation at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operation at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operational issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operation down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma grid is sufficient to reduce the electron temperature below the target value of 1 eV and to reduce together with the bias applied between the differently shaped bias plate and the plasma grid the amount of co-extracted electrons. An asymmetry of the co-extracted electron currents in the two grid segments is measured, varying strongly with filter field and bias. Contrary to the prototype source, a dedicated plasma drift in vertical direction is not observed. As in the prototype source, the performance in deuterium is limited by the amount of co-extracted electrons in short as well as in long pulse operation. Caesium conditioning is much harder in deuterium than in hydrogen for which fast and reproducible conditioning is achieved. First estimates reveal a caesium consumption comparable to the one in the prototype source despite the large size.

  8. Negative hydrogen ion beam extracted from a Bernas-type ion source

    SciTech Connect

    Miyamoto, N.; Wada, M.

    2011-09-26

    Negative hydrogen (H{sup -}) ion beam was produced without cesium seeding by a Bernas-type ion source with a coaxial hot cathode. The amount of H{sup -} ion beam current extracted from an original Bernas-type ion source using a hairpin shape filament as a hot cathode was 1 {mu}A with the 0.4 A arc current, while that 300 eV beam energy. In the other hand, H{sup -} ion beam current using the Bernas-type ion source with a coaxial hot cathode reached 4 {mu}A under the same condition. Production efficiency was enhanced by the focused plasma produced by a coaxial hot cathode.

  9. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  10. Electrical shielding box measurement of the negative hydrogen beam from Penning ion gauge ion source

    SciTech Connect

    Wang, T.; Yang, Z.; Dong, P.; Long, J. D.; He, X. Z.; Zhang, K. Z.; Zhang, L. W.; Wang, X.

    2012-06-15

    The cold-cathode Penning ion gauge (PIG) type ion source has been used for generation of negative hydrogen (H{sup -}) ions as the internal ion source of a compact cyclotron. A novel method called electrical shielding box dc beam measurement is described in this paper, and the beam intensity was measured under dc extraction inside an electrical shielding box. The results of the trajectory simulation and dc H{sup -} beam extraction measurement were presented. The effect of gas flow rate, magnetic field strength, arc current, and extraction voltage were also discussed. In conclusion, the dc H{sup -} beam current of about 4 mA from the PIG ion source with the puller voltage of 40 kV and arc current of 1.31 A was extrapolated from the measurement at low extraction dc voltages.

  11. A large-area RF source for negative hydrogen ions

    NASA Astrophysics Data System (ADS)

    Frank, P.; Feist, J. H.; Kraus, W.; Speth, E.; Heinemann, B.; Probst, F.; Trainham, R.; Jacquot, C.

    1998-08-01

    In a collaboration with CEA Cadarache, IPP is presently developing an rf source, in which the production of negative ions (H-/D-) is being investigated. It utilizes PINI-size rf sources with an external antenna and for the first step a small size extraction system with 48 cm2 net extraction area. First results from BATMAN (Ba¯varian T_est Ma¯chine for N_egative Ions) show (without Cs) a linear dependence of the negative ion yield with rf power, without any sign of saturation. At elevated pressure (1.6 Pa) a current density of 4.5 mA/cm2 H- (without Cs) has been found so far. At medium pressure (0.6 Pa) the current density is lower by approx. a factor of 5, but preliminary results with Cesium injection show a relative increase by almost the same factor in this pressure range. Langmuir probe measurements indicate an electron temperature Te>2 eV close to the plasma grid with a moderate magnetic filter (700 Gcm). Attempts to improve the performance by using different magnetic configurations and different wall materials are under way.

  12. Effect of nickel grid parameters on production of negative hydrogen ions

    SciTech Connect

    Oohara, W.; Yokoyama, H.; Takeda, Toshiaki; Maetani, Y.; Takeda, Takashi; Kawata, K.

    2014-06-15

    Negative hydrogen ions are produced by plasma-assisted catalytic ionization using a nickel grid. When positive ions passing through the grid are decelerated by an electric field, the extraction current density of passing positive ions is sharply reduced by neutralization and negative ionization of the ions. This phenomenon is found to depend on the specific surface area of the grid and the current density.

  13. A large-area RF source for negative hydrogen ions

    SciTech Connect

    Frank, P.; Feist, J. H.; Kraus, W.; Speth, E.; Heinemann, B.; Probst, F.; Trainham, R.; Jacquot, C.

    1998-08-20

    In a collaboration with CEA Cadarache, IPP is presently developing an rf source, in which the production of negative ions (H{sup -}/D{sup -}) is being investigated. It utilizes PINI-size rf sources with an external antenna and for the first step a small size extraction system with 48 cm{sup 2} net extraction area. First results from BATMAN (Bavarian T lowbar est Machine for N lowbar egative Ions) show (without Cs) a linear dependence of the negative ion yield with rf power, without any sign of saturation. At elevated pressure (1.6 Pa) a current density of 4.5 mA/cm{sup 2} H{sup -} (without Cs) has been found so far. At medium pressure (0.6 Pa) the current density is lower by approx. a factor of 5, but preliminary results with Cesium injection show a relative increase by almost the same factor in this pressure range. Langmuir probe measurements indicate an electron temperature T{sub e}>2 eV close to the plasma grid with a moderate magnetic filter (700 Gcm). Attempts to improve the performance by using different magnetic configurations and different wall materials are under way.

  14. Optimum plasma grid bias for a negative hydrogen ion source operation with Cs

    NASA Astrophysics Data System (ADS)

    Bacal, Marthe; Sasao, Mamiko; Wada, Motoi; McAdams, Roy

    2016-02-01

    The functions of a biased plasma grid of a negative hydrogen (H-) ion source for both pure volume and Cs seeded operations are reexamined. Proper control of the plasma grid bias in pure volume sources yields: enhancement of the extracted negative ion current, reduction of the co-extracted electron current, flattening of the spatial distribution of plasma potential across the filter magnetic field, change in recycling from hydrogen atomic/molecular ions to atomic/molecular neutrals, and enhanced concentration of H- ions near the plasma grid. These functions are maintained in the sources seeded with Cs with additional direct emission of negative ions under positive ion and neutral hydrogen bombardment onto the plasma electrode.

  15. Caesium Free Negative Ion Sources for Neutral Beam Injectors: a Study of Negative Ion Production on Graphite Surface in Hydrogen and Deuterium Plasma

    SciTech Connect

    Schiesko, L.; Carrere, M.; Cartry, G.; Layet, J.-M.

    2009-03-12

    Negative ion generation on HOPG graphite surface has been studied in hydrogen and deuterium plasma. We measure Ion Distribution Function (IDF) of negative ions coming from graphite surface bombarded by positive ions in H{sub 2}/D{sub 2} plasmas. We showed that negative ions flux was proportional to positive ion flux and was strongly dependant on impinging energy. IDF study shows two generation mechanisms are involved: sputtering of adsorbed H/D as negative ions and, in a less important way, double electron capture. We compare H{sub 2}/D{sub 2} plasmas, and point out isotopic effect between H{sup -} and D{sup -} production.

  16. Laser photodetachment diagnostics of a 1/3-size negative hydrogen ion source for NBI

    SciTech Connect

    Geng, S.; Tsumori, K.; Nakano, H.; Kisaki, M.; Ikeda, K.; Takeiri, Y.; Osakabe, M.; Nagaoka, K.; Kaneko, O.

    2015-04-08

    To investigate the flows of charged particles in front of the plasma grid (PG) in a negative hydrogen ion source, the information of the local densities of electrons and negative hydrogen ions (H-) are necessary. For this purpose, the laser photodetachment is applied for pure hydrogen plasmas and Cs-seeded plasma in a 1/3-size negative hydrogen ion source in NIFS-NBI test stand. The H- density obtained by photodetachment is calibrated by the results from cavity ring-down (CRD). The pressure dependence and PG bias dependence of the local H- density are presented and discussed. The results show that H- density increases significantly by seeding Cs into the plasma. In Cs-seeded plasma, relativity exists between the H- ion density and plasma potential.

  17. Extraction of negative hydrogen ions from a compact 14 GHz microwave ion source

    SciTech Connect

    Wada, M.; Kasuya, T.; Nishida, T.; Kenmotsu, T.; Maeno, S.; Nishiura, M.; Shinto, K.; Yamaoka, H.

    2012-02-15

    A pair of permanent magnets has formed enough intensity to realize electron cyclotron resonance condition for a 14 GHz microwave in a 2 cm diameter 9 cm long alumina discharge chamber. A three-electrode extraction system assembled in a magnetic shielding has formed a stable beam of negative hydrogen ions (H{sup -}) in a direction perpendicular to the magnetic field. The measured H{sup -} current density was about 1 mA/cm{sup 2} with only 50 W of discharge power, but the beam intensity had shown saturation against further increase in microwave power. The beam current decreased monotonically against increasing pressure.

  18. Extraction of negative hydrogen ions from a compact 14 GHz microwave ion source.

    PubMed

    Wada, M; Kasuya, T; Kenmotsu, T; Maeno, S; Nishida, T; Nishiura, M; Shinto, K; Yamaoka, H

    2012-02-01

    A pair of permanent magnets has formed enough intensity to realize electron cyclotron resonance condition for a 14 GHz microwave in a 2 cm diameter 9 cm long alumina discharge chamber. A three-electrode extraction system assembled in a magnetic shielding has formed a stable beam of negative hydrogen ions (H(-)) in a direction perpendicular to the magnetic field. The measured H(-) current density was about 1 mA∕cm(2) with only 50 W of discharge power, but the beam intensity had shown saturation against further increase in microwave power. The beam current decreased monotonically against increasing pressure.

  19. Roles of a plasma grid in a negative hydrogen ion source

    SciTech Connect

    Bacal, M.; Sasao, M.; Wada, M.; McAdams, R.

    2015-04-08

    The plasma grid is electrically biased with respect to other parts of source chamber wall in both volume sources and sources seeded with alkali metals. The roles of the plasma grid in these two kinds of sources will be described. The main functions of the plasma grid in volume sources are: optimizing the extracted negative ion current, reducing the co-extracted electron current, controlling the axial plasma potential profile, recycling the hydrogen atoms to molecules, concentrating the negative ions near its surface and, when biased positive, depleting the electron population near its surface. These functions are maintained in the sources seeded with alkali metals. However an additional function appears in the Cs seeded sources, namely direct emission of negative ions under positive ion and neutral hydrogen bombardment.

  20. Research progress on ionic plasmas generated in an intense hydrogen negative ion source

    SciTech Connect

    Takeiri, Y. Tsumori, K.; Nagaoka, K.; Kaneko, O.; Ikeda, K.; Nakano, H.; Kisaki, M.; Tokuzawa, T.; Osakabe, M.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Sekiguchi, H.; Geng, S.

    2015-04-08

    Characteristics of ionic plasmas, observed in a high-density hydrogen negative ion source, are investigated with a multi-diagnostics system. The ionic plasma, which consists of hydrogen positive- and negative-ions with a significantly low-density of electrons, is generated in the ion extraction region, from which the negative ions are extracted through the plasma grid. The negative ion density, i.e., the ionic plasma density, as high as the order of 1×10{sup 17}m{sup −3}, is measured with cavity ring-down spectroscopy, while the electron density is lower than 1×10{sup 16}m{sup −3}, which is confirmed with millimeter-wave interferometer. Reduction of the negative ion density is observed at the negative ion extraction, and at that time the electron flow into the ionic plasma region is observed to conserve the charge neutrality. Distribution of the plasma potential is measured in the extraction region in the direction normal to the plasma grid surface with a Langmuir probe, and the results suggest that the sheath is formed at the plasma boundary to the plasma grid to which the bias voltage is applied. The beam extraction should drive the negative ion transport in the ionic plasma across the sheath formed on the extraction surface. Larger reduction of the negative ions at the beam extraction is observed in a region above the extraction aperture on the plasma grid, which is confirmed with 2D image measurement of the Hα emission and cavity ring-down spectroscopy. The electron distribution is also measured near the plasma grid surface. These various properties observed in the ionic plasma are discussed.

  1. Linac4 low energy beam measurements with negative hydrogen ions

    NASA Astrophysics Data System (ADS)

    Scrivens, R.; Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-01

    Linac4, a 160 MeV normal-conducting H- linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H- beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  2. Linac4 low energy beam measurements with negative hydrogen ions

    SciTech Connect

    Scrivens, R. Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-15

    Linac4, a 160 MeV normal-conducting H{sup −} linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H{sup −} beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  3. Linac4 low energy beam measurements with negative hydrogen ions.

    PubMed

    Scrivens, R; Bellodi, G; Crettiez, O; Dimov, V; Gerard, D; Granemann Souza, E; Guida, R; Hansen, J; Lallement, J-B; Lettry, J; Lombardi, A; Midttun, Ø; Pasquino, C; Raich, U; Riffaud, B; Roncarolo, F; Valerio-Lizarraga, C A; Wallner, J; Yarmohammadi Satri, M; Zickler, T

    2014-02-01

    Linac4, a 160 MeV normal-conducting H(-) linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H(-) beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  4. Modelling the ion source for ITER NBI: from the generation of negative hydrogen ions to their extraction

    NASA Astrophysics Data System (ADS)

    Wünderlich, D.; Mochalskyy, S.; Fantz, U.; Franzen, P.; the NNBI-Team

    2014-02-01

    The neutral beam injection (NBI) system for ITER is based on a large (Asource = 1.9 × 0.9 m2) negative hydrogen or deuterium ion source. In this source negative ions are produced in a low-pressure (pfill ≈ 0.3 Pa) plasma by conversion of atoms and protons on a caesiated molybdenum surface with low work function. Then the negative ions are transported through the plasma to the extraction system where extraction of these ions and co-extraction of electrons also take place. This paper describes the status of the modelling activities connected with the negative ion test facilities of IPP Garching. It is illustrated that these modelling activities constitute a strong support of the experimental activities connected with the development of the negative ion source for ITER NBI. Several numerical codes developed in the past years—in close collaboration with the experiment—and their results are introduced. Focus is laid on the production, transport and extraction of negative hydrogen ions and on the inevitable co-extraction of electrons.

  5. Operation of RF driven negative ion source in a pure-hydrogen mode

    SciTech Connect

    Abdrashitov, G.; Belchenko, Yu. Gusev, I.; Senkov, D.; Sanin, A.; Shikhovtsev, I.; Kondakov, A.; Ivanov, A. A.; Sotnikov, O.

    2015-04-08

    The production of negative hydrogen ions in the radio-frequency driven long-pulsed source with external antenna is studied. RF drivers with various geometry of external antenna, Faraday shield and magnets at the rear flange were examined. H- beam extraction through the single emission aperture was performed in the source pure-hydrogen mode with no external seed of alkali additives. H- beam with ion emission current density up to 5 mA/cm{sup 2} and energy up to 75 keV was regularly obtained in the 1 s pulses of the pure-hydrogen mode. The regular temporal increase of H- ion production due to deposition of impurities on the plasma grid surface was recorded. The H- emission current density increased up to 9 mA/cm{sup 2} in this case.

  6. Cesium dynamics in long pulse operation of negative hydrogen ion sources for fusion

    SciTech Connect

    Fantz, U.; Wimmer, C.

    2012-02-15

    Large scale negative hydrogen ion sources operating stable for 1 h (cw mode) are required for the neutral beam heating system of the fusion experiment ITER. The formation of negative hydrogen ions relies on the surface effect for which cesium is evaporated into the source. In order to monitor the cesium dynamics the laser absorption spectroscopy technique is applied to the long pulse test facility MANITU. In the vacuum phase, without plasma operation the evaporation of cesium and the built-up of the cesium in the source are measured. Typical neutral cesium densities are 10{sup 15} m{sup -3}. During plasma operation and after the plasma phase a high cesium dynamics is observed, showing also depletion of cesium during long pulses with low cesium amount. The co-extracted electron current decreases with the cesium amount to a certain level whereas the ion current indicates an optimum density range.

  7. Development of spectrally selective imaging system for negative hydrogen ion source

    SciTech Connect

    Ikeda, K. Nakano, H.; Tsumori, K.; Kisaki, M.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.

    2014-02-15

    A spectrally selective imaging system has been developed to obtain a distribution of H{sub α} emissions at the extraction region in a hydrogen negative ion source. The diagnostic system consisted of an aspherical lens, optical filters, a fiber image conduit, and a charge coupled device detector was installed on the 1/3-scaled hydrogen negative ion source in the National Institute for Fusion Science. The center of sight line passes beside the plasma grid (PG) surface with the distance of 11 mm, and the viewing angle has coverage 35 mm from the PG surface. Two dimensional H{sub α} distribution in the range up to 20 mm from the PG surface was clearly observed. The reduction area for H{sub α} emission caused by beam extraction was widely distributed in the extraction region near the PG surface.

  8. Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions

    SciTech Connect

    Valerio-Lizarraga, Cristhian A.; Lallement, Jean-Baptiste; Lettry, Jacques; Scrivens, Richard; Leon-Monzon, Ildefonso; Midttun, Øystein

    2014-02-15

    The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H{sup −} beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.

  9. A collisional radiative model of hydrogen plasmas developed for diagnostic purposes of negative ion sources

    NASA Astrophysics Data System (ADS)

    Iordanova, Snejana; Paunska, Tsvetelina

    2016-02-01

    A collisional radiative model of low-pressure hydrogen plasmas is elaborated and applied in optical emission spectroscopy diagnostics of a single element of a matrix source of negative hydrogen ions. The model accounts for the main processes determining both the population densities of the first ten states of the hydrogen atom and the densities of the positive hydrogen ions H+, H2+, and H3+. In the calculations, the electron density and electron temperature are varied whereas the atomic and molecular temperatures are included as experimentally obtained external parameters. The ratio of the Hα to Hβ line intensities is calculated from the numerical results for the excited state population densities, obtained as a solution of the set of the steady-state rate balance equations. The comparison of measured and theoretically obtained ratios of line intensities yields the values of the electron density and temperature as well as of the degree of dissociation, i.e., of the parameters which have a crucial role for the volume production of the negative ions.

  10. First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources

    SciTech Connect

    Schiesko, L. Hopf, C.; Höschen, T.; Meisl, G.; Encke, O.; Heinemann, B.; Fantz, U.; Cartry, G.; Amsalem, P.; Achkasov, K.

    2015-08-21

    A study was conducted on the properties of molybdenum implanted with caesium as an approach to reduce the Cs consumption of negative hydrogen ion sources based on evaporated Cs. The depth profiles of the implanted Cs were simulated by SDTrimSP and experimentally determined by X-ray photoelectron spectroscopy depth profiling. In particular, one year after implantation, the depth profiles showed no signs of Cs diffusion into the molybdenum, suggesting long term stability of the implanted Cs atoms. The H{sup −} surface generation mechanisms on the implanted samples in hydrogen plasma were investigated, and the stability of the H{sup −} yield during four hours low power hydrogen plasma discharges was demonstrated. An estimation of the work function reduction (−0.8 eV) by the Cs implantation was performed, and a comparison of the relative negative ion yields between the implanted samples and highly oriented pyrolitic graphite showed that the Cs doped Mo negative ion yield was larger.

  11. Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

    SciTech Connect

    Rauner, D.; Kurutz, U.; Fantz, U.

    2015-04-08

    As the negative hydrogen ion density n{sub H{sup −}} is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H{sup −} is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H{sup −} is produced in the plasma volume, laser photodetachment is applied as the standard method to measure n{sub H{sup −}}. The additional application of CRDS provides the possibility to directly obtain absolute values of n{sub H{sup −}}, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H{sup −} production and destruction processes. The modelled densities are adapted to the absolute measurements of n{sub H{sup −}} via CRDS, allowing to identify collisions of H{sup −} with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H{sup −} in the plasma volume at HOMER. Furthermore, the characteristic peak of n{sub H{sup −}} observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as n{sub e} determines

  12. 3D modeling of the electron energy distribution function in negative hydrogen ion sources.

    PubMed

    Terasaki, R; Fujino, I; Hatayama, A; Mizuno, T; Inoue, T

    2010-02-01

    For optimization and accurate prediction of the amount of H-ion production in negative ion sources, analysis of electron energy distribution function (EEDF) is necessary. We are developing a numerical code which analyzes EEDF in the tandem-type arc-discharge source. It is a three-dimensional Monte Carlo simulation code with realistic geometry and magnetic configuration. Coulomb collision between electrons is treated with the "binary collision" model and collisions with hydrogen species are treated with the "null-collision" method. We applied this code to the analysis of the JAEA 10 A negative ion source. The numerical result shows that the obtained EEDF is in good agreement with experimental results.

  13. Production of beam of negative hydrogen and deuterium ions from source with electron cyclotron resonance

    SciTech Connect

    Golovanivskii, K.S.; Dzhayamanna, K.; Dugar-Zhabon, V.D.

    1988-09-01

    The GELIOS-H/sup /minus// ion source is described; it has electron cyclotron resonance and is designed for generation of negative hydrogen and deuterium ions. The source consumes up to 100 W of microwave power at a frequency of 2.4 GHz and provides a stationary beam of H/sup /minus// ions of up to 1.5 mA and D/sup /minus// ions of up to 1.0 mA for an exit-aperture diameter of 6.2 mm and an extraction voltage of 4.5 kV. The life of the source is limited only by the life of the microwave generator.

  14. Operation Status of the J-PARC Negative Hydrogen Ion Source

    SciTech Connect

    Oguri, H.; Ikegami, K.; Ohkoshi, K.; Namekawa, Y.; Ueno, A.

    2011-09-26

    A cesium-free negative hydrogen ion source driven with a lanthanum hexaboride (LaB{sub 6}) filament is being operated without any serious trouble for approximately four years in J-PARC. Although the ion source is capable of producing an H{sup -} ion current of more than 30 mA, the current is routinely restricted to approximately 16 mA at present for the stable operation of the RFQ linac which has serious discharge problem from September 2008. The beam run is performed during 1 month cycle, which consisted of a 4-5 weeks beam operation and a few days down-period interval. At the recent beam run, approximately 700 h continuous operation was achieved. At every runs, the beam interruption time due to the ion source failure is a few hours, which correspond to the ion source availability of more than 99%. The R and D work is being performed in parallel with the operation in order to enhance the further beam current. As a result, the H{sup -} ion current of 61 mA with normalized rms emittance of 0.26 {pi}mm.mrad was obtained by adding a cesium seeding system to a J-PARC test ion source which has the almost same structure with the present J-PARC ion source.

  15. Numerical analysis of electronegative plasma in the extraction region of negative hydrogen ion sources

    SciTech Connect

    Kuppel, S.; Matsushita, D.; Hatayama, A.; Bacal, M.

    2011-01-01

    This numerical study focuses on the physical mechanisms involved in the extraction of volume-produced H{sup -} ions from a steady state laboratory negative hydrogen ion source with one opening in the plasma electrode (PE) on which a dc-bias voltage is applied. A weak magnetic field is applied in the source plasma transversely to the extracted beam. The goal is to highlight the combined effects of the weak magnetic field and the PE bias voltage (upon the extraction process of H{sup -} ions and electrons). To do so, we focus on the behavior of electrons and volume-produced negative ions within a two-dimensional model using the particle-in-cell method. No collision processes are taken into account, except for electron diffusion across the magnetic field using a simple random-walk model at each time step of the simulation. The results show first that applying the magnetic field (without PE bias) enhances H{sup -} ion extraction, while it drastically decreases the extracted electron current. Secondly, the extracted H{sup -} ion current has a maximum when the PE bias is equal to the plasma potential, while the extracted electron current is significantly reduced by applying the PE bias. The underlying mechanism leading to the above results is the gradual opening by the PE bias of the equipotential lines towards the parts of the extraction region facing the PE. The shape of these lines is due originally to the electron trapping by the magnetic field.

  16. Over-the-barrier electron detachment in the hydrogen negative ion

    NASA Astrophysics Data System (ADS)

    Milošević, M. Z.; Simonović, N. S.

    2016-09-01

    The electron detachment from the hydrogen negative ion in strong fields is studied using the two-electron and different single-electron models within the quasistatic approximation. Special attention is payed to over-the-barrier regime where the Stark saddle is suppressed below the lowest energy level. It is demonstrated that the single-electron description of the lowest state of the ion, that is a good approximation for weak fields, fails in this and partially in the tunnelling regime. The exact lowest state energies and detachment rates for the ion at different strengths of the applied field are determined by solving the eigenvalue problem of the full two-electron Hamiltonian. A simple formula for the rate, which is valid in both regimes, is determined by fitting the exact data to the expression estimated using single-electron descriptions.

  17. Single discharge of the matrix source of negative hydrogen ions: Influence of the neutral particle dynamics

    SciTech Connect

    Paunska, Ts.; Todorov, D. Shivarova, A.; Tarnev, Kh.

    2015-04-08

    The study presents two-dimensional (2D) fluid-plasma-model description of a planar-coil inductively-driven discharge, considered as a single element of a matrix source of volume-produced negative hydrogen ions. Whereas the models developed up to now have been directed towards description of the charged particle behavior in the discharge, including that of the negative ions, this model stresses on the role of the neutral particle dynamics and of the surface processes in the formation of the discharge structure. The latter is discussed based on comparison of results obtained for discharges in a flowing gas and at a constant gas pressure as well as for different values of the coefficient of atom recombination on the walls. The conclusions are that the main plasma parameters – electron density and temperature and plasma potential – determining the gas discharge regime stay stable, regardless of changes in the redistribution of the densities of the neutral particles and of the positive ions. With regards to the volume production of the ions, which requires high density of (vibrationally excited) molecules, the impact on the degree of dissociation of the coefficient of atom recombination on the wall is discussed.

  18. Monitoring Surface Condition of Plasma Grid of a Negative Hydrogen Ion Source

    SciTech Connect

    Wada, M.; Kasuya, T.; Tokushige, S.; Kenmotsu, T.

    2011-09-26

    Surface condition of a plasma grid in a negative hydrogen ion source is controlled so as to maximize the beam current under a discharge operation with introducing Cs into the ion source. Photoelectric current induced by laser beams incident on the plasma grid can produce a signal to monitor the surface condition, but the signal detection can be easily hindered by plasma noise. Reduction in size of a detection electrode embedded in the plasma grid can improve signal-to-noise ratio of the photoelectric current from the electrode. To evaluate the feasibility of monitoring surface condition of a plasma gird by utilizing photoelectric effect, a small experimental setup capable of determining quantum yields of a surface in a cesiated plasma environment is being assembled. Some preliminary test results of the apparatus utilizing oxide cathodes are reported.

  19. Electron cyclotron resonance heating by magnetic filter field in a negative hydrogen ion source.

    PubMed

    Kim, June Young; Cho, Won-Hwi; Dang, Jeong-Jeung; Chung, Kyoung-Jae; Hwang, Y S

    2016-02-01

    The influence of magnetic filter field on plasma properties in the heating region has been investigated in a planar-type inductively coupled radio-frequency (RF) H(-) ion source. Besides filtering high energy electrons near the extraction region, the magnetic filter field is clearly observed to increase the electron temperature in the heating region at low pressure discharge. With increasing the operating pressure, enhancement of electron temperature in the heating region is reduced. The possibility of electron cyclotron resonance (ECR) heating in the heating region due to stray magnetic field generated by a filter magnet located at the extraction region is examined. It is found that ECR heating by RF wave field in the discharge region, where the strength of an axial magnetic field is approximately ∼4.8 G, can effectively heat low energy electrons. Depletion of low energy electrons in the electron energy distribution function measured at the heating region supports the occurrence of ECR heating. The present study suggests that addition of axial magnetic field as small as several G by an external electromagnet or permanent magnets can greatly increase the generation of highly ro-vibrationally excited hydrogen molecules in the heating region, thus improving the performance of H(-) ion generation in volume-produced negative hydrogen ion sources. PMID:26931999

  20. Electron cyclotron resonance heating by magnetic filter field in a negative hydrogen ion source.

    PubMed

    Kim, June Young; Cho, Won-Hwi; Dang, Jeong-Jeung; Chung, Kyoung-Jae; Hwang, Y S

    2016-02-01

    The influence of magnetic filter field on plasma properties in the heating region has been investigated in a planar-type inductively coupled radio-frequency (RF) H(-) ion source. Besides filtering high energy electrons near the extraction region, the magnetic filter field is clearly observed to increase the electron temperature in the heating region at low pressure discharge. With increasing the operating pressure, enhancement of electron temperature in the heating region is reduced. The possibility of electron cyclotron resonance (ECR) heating in the heating region due to stray magnetic field generated by a filter magnet located at the extraction region is examined. It is found that ECR heating by RF wave field in the discharge region, where the strength of an axial magnetic field is approximately ∼4.8 G, can effectively heat low energy electrons. Depletion of low energy electrons in the electron energy distribution function measured at the heating region supports the occurrence of ECR heating. The present study suggests that addition of axial magnetic field as small as several G by an external electromagnet or permanent magnets can greatly increase the generation of highly ro-vibrationally excited hydrogen molecules in the heating region, thus improving the performance of H(-) ion generation in volume-produced negative hydrogen ion sources.

  1. A collisional radiative model for caesium and its application to an RF source for negative hydrogen ions

    SciTech Connect

    Wünderlich, D. Wimmer, C.; Friedl, R.

    2015-04-08

    A collisional radiative (CR) model for caesium atoms in low-temperature, low-pressure hydrogen-caesium plasmas is introduced. This model includes the caesium ground state, 14 excited states, the singly charged caesium ion and the negative hydrogen ion. The reaction probabilities needed as input are based on data from the literature, using some scaling and extrapolations. Additionally, new cross sections for electron collision ionization and three-body recombination have been calculated. The relevance of mutual neutralization of positive caesium ions and negative hydrogen ions is highlighted: depending on the densities of the involved particle species, this excitation channel can have a significant influence on the population densities of excited states in the caesium atom. This strong influence is successfully verified by optical emission spectroscopy measurements performed at the IPP prototype negative hydrogen ion source for ITER NBI. As a consequence, population models for caesium in electronegative low-temperature, low-pressure hydrogen-caesium plasmas need to take into account the mutual neutralization process. The present CR model is an example for such models and represents an important prerequisite for deducing the total caesium density in surface production based negative hydrogen ion sources.

  2. Development of a Negative Hydrogen Ion Source for Spatial Beam Profile Measurement of a High Intensity Positive Ion Beam

    SciTech Connect

    Shinto, Katsuhiro; Wada, Motoi; Nishida, Tomoaki; Demura, Yasuhiro; Sasaki, Daichi; Tsumori, Katsuyoshi; Nishiura, Masaki; Kaneko, Osamu; Kisaki, Masashi; Sasao, Mamiko

    2011-09-26

    We have been developing a negative hydrogen ion (H{sup -} ion) source for a spatial beam profile monitor of a high intensity positive ion beam as a new diagnostic tool. In case of a high intensity continuous-wave (CW) deuteron (D{sup +}) beam for the International Fusion Materials Irradiation Facility (IFMIF), it is difficult to measure the beam qualities in the severe high radiation environment during about one-year cyclic operation period. Conventional techniques are next to unusable for diagnostics in the operation period of about eleven months and for maintenance in the one-month shutdown period. Therefore, we have proposed an active beam probe system by using a negative ion beam and started an experimental study for the proof-of-principle (PoP) of the new spatial beam profile monitoring tool. In this paper, we present the status of development of the H{sup -} ion source as a probe beam source for the PoP experiment.

  3. Study on a negative hydrogen ion source with hot cathode arc discharge

    SciTech Connect

    Lin, S. H. Fang, X.; Zhang, H. J.; Qian, C.; Ma, B. H.; Wang, H.; Li, X. X.; Zhang, X. Z.; Sun, L. T.; Zhang, Z. M.; Yuan, P.; Zhao, H. W.

    2014-02-15

    A negative hydrogen (H{sup −}) ion source with hot cathode arc discharge was designed and fabricated as a primary injector for a 10 MeV PET cyclotron at IMP. 1 mA dc H{sup −} beam with ε {sub N,} {sub RMS} = 0.08 π mm mrad was extracted at 25 kV. Halbach hexapole was adopted to confine the plasma. The state of arc discharge, the parameters including filament current, arc current, gas pressure, plasma electrode bias, and the ratio of I{sub e{sup −}}/I{sub H{sup −}} were experimentally studied. The discussion on the result, and opinions to improve the source were given.

  4. 3D self-consistent modeling of a matrix source of negative hydrogen ions.

    PubMed

    Tarnev, Kh; Demerdjiev, A; Shivarova, A; Lishev, St

    2016-02-01

    The paper is in the scope of studies on the rf driving of a matrix source of negative hydrogen ions: a matrix of small radius discharges with planar-coil inductive driving and single aperture extraction from each discharge. The results from a three-dimensional model, in which plasma description is coupled to electrodynamics, confirm former conclusion that a single coil driving of the whole matrix by a zigzag coil with an omega-shaped conductor on the bottom of each discharge tube ensures efficient rf power deposition to the plasma. The latter is due to similarities with the rf driving of a single discharge by a single planar coil, shown by the obtained induced current and spatial distribution of the plasma parameters. Distinctions associated with the coil configuration as a single coil for the whole matrix are also discussed. PMID:26932005

  5. Plasma expansion across a transverse magnetic field in a negative hydrogen ion source for fusion

    NASA Astrophysics Data System (ADS)

    Fantz, U.; Schiesko, L.; Wünderlich, D.

    2014-08-01

    High power negative hydrogen ion sources operating at 0.3 Pa are a key component of the neutral beam injection systems for the international fusion experiment ITER. To achieve the required large ion current at a tolerable number of co-extracted electrons the source is equipped with a magnetic filter field (up to 10 mT). The IPP prototype source (1/8 of the area of the ITER source) has been equipped with a flexible magnetic filter frame to perform filter field studies (position, polarity, strength). Axial profiles of the plasma parameters are measured with two Langmuir probes, positioned in the upper and the lower half of the expansion chamber. In addition to the expected decrease in electron temperature and density a vertical drift develops the direction depending on the polarity of the field. Without field no drift is observed. The drift is less pronounced in caesium seeded discharges and almost vanishes in deuterium, indicating an influence of the ion mass on the drift. A comparison with results from a half-size ITER source reveals that the plasma is much more uniform in the large source.

  6. Quantification Of Cesium In Negative Hydrogen Ion Sources By Laser Absorption Spectroscopy

    SciTech Connect

    Fantz, U.; Wimmer, Ch.

    2011-09-26

    The use of cesium in negative hydrogen ion sources and the resulting cesium dynamics caused by the evaporation and redistribution in the vacuum and plasma phase makes a reliable and on-line monitoring of the cesium amount in the source highly desirable. For that purpose, a robust and compact laser absorption setup suitable for the ion source environment has been developed utilizing the Cs D{sub 2} resonance line at 852.1 nm. First measurements are taken in a small laboratory plasma chamber with cesium evaporation. A detection limit of {approx_equal}5x10{sup 13} m{sup -3} at a typical path length of 15 cm has been obtained with a dynamic range of more than three orders of magnitude, limited by line saturation at high densities. For on-line monitoring an automatic data analysis is established achieving a temporal resolution of 100 ms. The setup has then been applied to the ITER prototype ion sources developed at IPP. It is been shown that the method is well suited for routine measurements revealing a new insight into the cesium dynamics during source operation and cesium conditioning.

  7. Effects of roughness and temperature on low-energy hydrogen positive and negative ion reflection from silicon and carbon surfaces

    SciTech Connect

    Tanaka, N.; Kato, S.; Miyamoto, T.; Wada, M.; Nishiura, M.; Tsumori, K.; Matsumoto, Y.; Kenmotsu, T.; Okamoto, A.; Kitajima, S.; Sasao, M.; Yamaoka, H.

    2014-02-15

    Angle-resolved energy distribution functions of positive and negative hydrogen ions produced from a rough-finished Si surface under 1 keV proton irradiation have been measured. The corresponding distribution from a crystalline surface and a carbon surface are also measured for comparison. Intensities of positive and negative ions from the rough-finished Si are substantially smaller than those from crystalline Si. The angular distributions of these species are broader for rough surface than the crystalline surface. No significant temperature dependence for positive and negative ion intensities is observed for all samples in the temperature range from 300 to 400 K.

  8. Effects of roughness and temperature on low-energy hydrogen positive and negative ion reflection from silicon and carbon surfaces.

    PubMed

    Tanaka, N; Kato, S; Miyamoto, T; Nishiura, M; Tsumori, K; Matsumoto, Y; Kenmotsu, T; Okamoto, A; Kitajima, S; Sasao, M; Wada, M; Yamaoka, H

    2014-02-01

    Angle-resolved energy distribution functions of positive and negative hydrogen ions produced from a rough-finished Si surface under 1 keV proton irradiation have been measured. The corresponding distribution from a crystalline surface and a carbon surface are also measured for comparison. Intensities of positive and negative ions from the rough-finished Si are substantially smaller than those from crystalline Si. The angular distributions of these species are broader for rough surface than the crystalline surface. No significant temperature dependence for positive and negative ion intensities is observed for all samples in the temperature range from 300 to 400 K.

  9. A CW radiofrequency ion source for production of negative hydrogen ion beams for cyclotrons

    NASA Astrophysics Data System (ADS)

    Kalvas, T.; Tarvainen, O.; Komppula, J.; Koivisto, H.; Tuunanen, J.; Potkins, D.; Stewart, T.; Dehnel, M. P.

    2015-04-01

    A CW 13.56 MHz radiofrequency-driven ion source RADIS for production of H- and D- beams is under development for replacing the filament-driven ion source of the MCC30/15 cyclotron. The RF ion source has a 16-pole multicusp plasma chamber, an electromagnet-based magnetic filter and an external planar spiral RF antenna behind an AlN window. The extraction is a 5-electrode system with an adjustable puller electrode voltage for optimizing the beam formation, a water-cooled electron dump electrode and an accelerating einzel lens. At 2650 W of RF power, the source produces 1 mA of H- (2.6 mA/cm2), which is the intensity needed at injection for production of 200 µA H+ with the filament-driven ion source. A simple pepperpot device has been developed for characterizing the beam emittance. Plans for improving the power efficiency with the use of a new permanent magnet front plate is discussed.

  10. A CW radiofrequency ion source for production of negative hydrogen ion beams for cyclotrons

    SciTech Connect

    Kalvas, T.; Tarvainen, O.; Komppula, J.; Koivisto, H.; Tuunanen, J.; Potkins, D.; Stewart, T.; Dehnel, M. P.

    2015-04-08

    A CW 13.56 MHz radiofrequency-driven ion source RADIS for production of H{sup −} and D{sup −} beams is under development for replacing the filament-driven ion source of the MCC30/15 cyclotron. The RF ion source has a 16-pole multicusp plasma chamber, an electromagnet-based magnetic filter and an external planar spiral RF antenna behind an AlN window. The extraction is a 5-electrode system with an adjustable puller electrode voltage for optimizing the beam formation, a water-cooled electron dump electrode and an accelerating einzel lens. At 2650 W of RF power, the source produces 1 mA of H{sup −} (2.6 mA/cm{sup 2}), which is the intensity needed at injection for production of 200 µA H{sup +} with the filament-driven ion source. A simple pepperpot device has been developed for characterizing the beam emittance. Plans for improving the power efficiency with the use of a new permanent magnet front plate is discussed.

  11. Study of negative hydrogen ion beam optics using the 3D3V PIC model

    SciTech Connect

    Miyamoto, K.; Nishioka, S.; Goto, I.; Hatayama, A.; Hanada, M.; Kojima, A.

    2015-04-08

    The mechanism of negative ion extraction under real conditions with the complex magnetic field is studied by using the 3D PIC simulation code. The extraction region of the negative ion source for the negative ion based neutral beam injection system in fusion reactors is modelled. It is shown that the E x B drift of electrons is caused by the magnetic filter and the electron suppression magnetic field, and the resultant asymmetry of the plasma meniscus. Furthermore, it is indicated that that the asymmetry of the plasma meniscus results in the asymmetry of negative ion beam profile including the beam halo. It could be demonstrated theoretically that the E x B drift is not significantly weakened by the elastic collisions of the electrons with neutral particles.

  12. A discharge with a magnetic X-point as a negative hydrogen ion source

    SciTech Connect

    Tsankov, Tsanko; Czarnetzki, Uwe

    2011-09-26

    The study presents first results from investigations of a novel low-pressure plasma source, intended for a negative hydrogen ion production. The source utilizes a dc magnetic field, shaped to form a cusp with a magnetic null-point (X-point). Beside the common role of filtering out the high energy electrons, this magnetic field configuration ensures in the present case also an interesting mechanism of coupling the RF power to the plasma. Investigations performed using radio frequency modulation spectroscopy (RFMOS) reveal that the main power coupling to the electrons is confined in the region on one side of the X-point. The modulation of the light intensity indicates also the presence of a strong dc drift close to the plane of the X-point. Several hypothesises for its explanation are raised: an azimuthal diamagnetic drift due to strong axial gradients of the electron energy, the excitation of a standing helicon wave, which couples to the radial magnetic field in the plane of the X-point, or a Trivelpiece-Gould wave which is resonantly absorbed near the plane of the X-point.

  13. Characterisation of the properties of a negative hydrogen ion beam by several beam diagnostic techniques

    NASA Astrophysics Data System (ADS)

    Maurizio, R.; Fantz, U.; Bonomo, F.; Serianni, G.

    2016-06-01

    The beam properties of the BATMAN negative ion source, which is the prototype of one module of the source for the ITER neutral beam injection system, are characterised by means of three diagnostic techniques: beam emission spectroscopy (BES), the experimental calorimeter mini-STRIKE and a copper calorimeter. The main beam parameters—beam divergence, homogeneity and top-bottom asymmetries—are studied in different operational scenarios: with different magnetic filter field setups, source settings and with different gases (hydrogen or deuterium). Among all dependences, the influence of the magnetic field configuration on the beam and the evolution of the beam features during some conditioning days are investigated in detail. Data show that the stronger the filter field in the beam region, the higher the beam top-bottom asymmetry—likely a v× B effect. During the conditioning of the source, such vertical beam asymmetry increases as well, suggesting an inhomogeneous H -production at the first grid of the extraction system.

  14. On the meniscus formation and the negative hydrogen ion extraction from ITER neutral beam injection relevant ion source

    NASA Astrophysics Data System (ADS)

    Mochalskyy, S.; Wünderlich, D.; Ruf, B.; Fantz, U.; Franzen, P.; Minea, T.

    2014-10-01

    The development of a large area (Asource,ITER = 0.9 × 2 m2) hydrogen negative ion (NI) source constitutes a crucial step in construction of the neutral beam injectors of the international fusion reactor ITER. To understand the plasma behaviour in the boundary layer close to the extraction system the 3D PIC MCC code ONIX is exploited. Direct cross checked analysis of the simulation and experimental results from the ITER-relevant BATMAN source testbed with a smaller area (Asource,BATMAN ≈ 0.32 × 0.59 m2) has been conducted for a low perveance beam, but for a full set of plasma parameters available. ONIX has been partially benchmarked by comparison to the results obtained using the commercial particle tracing code for positive ion extraction KOBRA3D. Very good agreement has been found in terms of meniscus position and its shape for simulations of different plasma densities. The influence of the initial plasma composition on the final meniscus structure was then investigated for NIs. As expected from the Child-Langmuir law, the results show that not only does the extraction potential play a crucial role on the meniscus formation, but also the initial plasma density and its electronegativity. For the given parameters, the calculated meniscus locates a few mm downstream of the plasma grid aperture provoking a direct NI extraction. Most of the surface produced NIs do not reach the plasma bulk, but move directly towards the extraction grid guided by the extraction field. Even for artificially increased electronegativity of the bulk plasma the extracted NI current from this region is low. This observation indicates a high relevance of the direct NI extraction. These calculations show that the extracted NI current from the bulk region is low even if a complete ion-ion plasma is assumed, meaning that direct extraction from surface produced ions should be present in order to obtain sufficiently high extracted NI current density. The calculated extracted currents, both ions

  15. Tests on the extracted current density of negative hydrogen ions from a single element of the matrix source

    SciTech Connect

    Lishev, St.; Yordanov, D. Shivarova, A.

    2015-04-08

    Concepts for the extraction of volume-produced negative hydrogen ions from a rf matrix source (a matrix of small-radius discharges with a planar-coil inductive driving) are presented and discussed based on experimental results for the current densities of the extracted ions and the co-extracted electrons. The experiment has been carried out in a single discharge of the source: a rf discharge with a radius of 2.25 cm inductively driven by a 3.5-turn planar coil. The length of the discharge tube, the area of the reference electrode inserted in the discharge volume, the discharge modes, the magnetic filter and its position along the discharge length, the position of the permanent magnets for the separation of the co-extracted electrons from the extracted ions in the extraction device and the bias applied to its first electrode are considered as factors influencing the extracted currents of negative ions.

  16. Development of a novel radio-frequency negative hydrogen ion source in conically converging configuration.

    PubMed

    Jung, B K; Dang, J J; An, Y H; Chung, K J; Hwang, Y S

    2014-02-01

    Volume-produced negative ion source still requires enhancement of current density with lower input RF (radio-frequency) power in lower operating pressure for various applications. To confirm recent observation of efficient negative ion production with a short cylindrical chamber with smaller effective plasma size, the RF-driven transformer-coupled plasma H(-) ion source at Seoul National University is modified by adopting a newly designed quartz RF window to reduce the chamber length. Experiments with the reduced chamber length show a few times enhancement of H(-) ion beam current compared to that extracted from the previous chamber design, which is consistent with the measured H(-) ion population. Nevertheless, decrease in H(-) ion beam current observed in low pressure regime below ∼5 mTorr owing to insufficient filtering of high energy electrons in the extraction region needs to be resolved to address the usefulness of electron temperature control by the change of geometrical configuration of the discharge chamber. A new discharge chamber with conically converging configuration has been developed, in which the chamber diameter decreases as approaching to the extraction region away from the planar RF antenna such that stronger filter magnetic field can be utilized to prohibit high energy electrons from transporting to the extraction region. First experimental results for the H(-) ion beam extraction with this configuration show that higher magnetic filter field makes peak negative beam currents happen in lower operating pressure. However, overall decrease in H(-) ion beam current due to the change of chamber geometry still requires further study of geometrical effect on particle transport and optimization of magnetic field in this novel configuration.

  17. Low pressure and high power rf sources for negative hydrogen ions for fusion applications (ITER neutral beam injection).

    PubMed

    Fantz, U; Franzen, P; Kraus, W; Falter, H D; Berger, M; Christ-Koch, S; Fröschle, M; Gutser, R; Heinemann, B; Martens, C; McNeely, P; Riedl, R; Speth, E; Wünderlich, D

    2008-02-01

    The international fusion experiment ITER requires for the plasma heating and current drive a neutral beam injection system based on negative hydrogen ion sources at 0.3 Pa. The ion source must deliver a current of 40 A D(-) for up to 1 h with an accelerated current density of 200 Am/(2) and a ratio of coextracted electrons to ions below 1. The extraction area is 0.2 m(2) from an aperture array with an envelope of 1.5 x 0.6 m(2). A high power rf-driven negative ion source has been successfully developed at the Max-Planck Institute for Plasma Physics (IPP) at three test facilities in parallel. Current densities of 330 and 230 Am/(2) have been achieved for hydrogen and deuterium, respectively, at a pressure of 0.3 Pa and an electron/ion ratio below 1 for a small extraction area (0.007 m(2)) and short pulses (<4 s). In the long pulse experiment, equipped with an extraction area of 0.02 m(2), the pulse length has been extended to 3600 s. A large rf source, with the width and half the height of the ITER source but without extraction system, is intended to demonstrate the size scaling and plasma homogeneity of rf ion sources. The source operates routinely now. First results on plasma homogeneity obtained from optical emission spectroscopy and Langmuir probes are very promising. Based on the success of the IPP development program, the high power rf-driven negative ion source has been chosen recently for the ITER beam systems in the ITER design review process.

  18. Optimization of plasma parameters with magnetic filter field and pressure to maximize H- ion density in a negative hydrogen ion source

    NASA Astrophysics Data System (ADS)

    Cho, Won-Hwi; Dang, Jeong-Jeung; Kim, June Young; Chung, Kyoung-Jae; Hwang, Y. S.

    2016-02-01

    Transverse magnetic filter field as well as operating pressure is considered to be an important control knob to enhance negative hydrogen ion production via plasma parameter optimization in volume-produced negative hydrogen ion sources. Stronger filter field to reduce electron temperature sufficiently in the extraction region is favorable, but generally known to be limited by electron density drop near the extraction region. In this study, unexpected electron density increase instead of density drop is observed in front of the extraction region when the applied transverse filter field increases monotonically toward the extraction aperture. Measurements of plasma parameters with a movable Langmuir probe indicate that the increased electron density may be caused by low energy electron accumulation in the filter region decreasing perpendicular diffusion coefficients across the increasing filter field. Negative hydrogen ion populations are estimated from the measured profiles of electron temperatures and densities and confirmed to be consistent with laser photo-detachment measurements of the H- populations for various filter field strengths and pressures. Enhanced H- population near the extraction region due to the increased low energy electrons in the filter region may be utilized to increase negative hydrogen beam currents by moving the extraction position accordingly. This new finding can be used to design efficient H- sources with an optimal filtering system by maximizing high energy electron filtering while keeping low energy electrons available in the extraction region.

  19. Optimization of plasma parameters with magnetic filter field and pressure to maximize H⁻ ion density in a negative hydrogen ion source.

    PubMed

    Cho, Won-Hwi; Dang, Jeong-Jeung; Kim, June Young; Chung, Kyoung-Jae; Hwang, Y S

    2016-02-01

    Transverse magnetic filter field as well as operating pressure is considered to be an important control knob to enhance negative hydrogen ion production via plasma parameter optimization in volume-produced negative hydrogen ion sources. Stronger filter field to reduce electron temperature sufficiently in the extraction region is favorable, but generally known to be limited by electron density drop near the extraction region. In this study, unexpected electron density increase instead of density drop is observed in front of the extraction region when the applied transverse filter field increases monotonically toward the extraction aperture. Measurements of plasma parameters with a movable Langmuir probe indicate that the increased electron density may be caused by low energy electron accumulation in the filter region decreasing perpendicular diffusion coefficients across the increasing filter field. Negative hydrogen ion populations are estimated from the measured profiles of electron temperatures and densities and confirmed to be consistent with laser photo-detachment measurements of the H(-) populations for various filter field strengths and pressures. Enhanced H(-) population near the extraction region due to the increased low energy electrons in the filter region may be utilized to increase negative hydrogen beam currents by moving the extraction position accordingly. This new finding can be used to design efficient H(-) sources with an optimal filtering system by maximizing high energy electron filtering while keeping low energy electrons available in the extraction region. PMID:26932018

  20. Negative ion generator

    DOEpatents

    Stinnett, Regan W.

    1984-01-01

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions.

  1. Negative ion generator

    DOEpatents

    Stinnett, R.W.

    1984-05-08

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions. 8 figs.

  2. Photodetachment Spectrum of Hydrogen Negative Ion Near a Partially Reflecting Spherical Surface

    NASA Astrophysics Data System (ADS)

    Afaq, A.; Iqbal, Azmat; Rahman, Amin Ur; Khan, Naveed; Aleem, Fazal-e.-; Ansari, M. Mushraf

    2016-10-01

    Photodetachment of negative ions near surfaces is of great interest in view of its fundamental significance and technological applications. We reinvestigate the dynamics of photoelectrons in H - photodetachment near a partially reflecting spherical surface by the semiclassical closed-orbit theory. Reflection parameter R and curvature K is used to observe inelastic and spherical effects of the surface, respectively. The classical action is evaluated from the photodetached electron trajectories incident normally at the surface, arising simultaneously from the source and its image. The derived analytical formula of photodetachment cross section correctly recovers the results of reflective spherical surface published recently based on theoretical imaging method.

  3. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  4. Compression effects in inductively coupled, high-power radio-frequency discharges for negative hydrogen ion production

    NASA Astrophysics Data System (ADS)

    Wilhelm, Rolf

    2003-02-01

    In the paper we present a simplified model description of inductively coupled plasma discharges operating at a rather high radio-frequency (rf) power. In this case the induced high plasma currents can cause periodic compressions over a substantial radial distance. Such conditions are obviously given in rf driven 1 MHz/150 kW plasma sources developed at the Institute for Plasma Physics Garching for negative (hydrogen) ion production in future neutral beam injection (NBI) systems for nuclear fusion research, such as the 1 MeV/50 MW NBI system for the International Thermonuclear Experimental Reactor [T. Inoue, R. Hemsworth, V. Kulygin, and Y. Okumura, Fusion Eng. Design 55, 291 (2001)]. The given model describes quite well the compression and other features of the discharge. The results include the Ohmic power input (i.e., electron heating), the resulting density build-up, and—as a new feature—periodical plasma compressions, leading to a direct energy input also into the plasma ions. The model also explains the strange effect of small argon admixtures, which improve the negative ion yield in rf sources by a factor of up to 2-3 (but which have no effect in conventional dc arc sources). With the calculated dependencies from external parameters (e.g., rf-power and frequency, gas pressure, ion mass or the specific geometry), the modeling may help for the further optimization of the rf source.

  5. Cross sections of one- and two-photon detachment of the hydrogen negative ion

    NASA Astrophysics Data System (ADS)

    Pazdzersky, V. A.; Usachenko, V. I.; Ushnurtsev, A. V.

    2000-03-01

    The model non-local separable Yamaguchi potential is proposed as being particularly appropriate for the description of the interaction of a detached electron with its parent residual atomic core in a theoretical treatment of the processes of H- negative ion multiphoton detachment in a monochromatic electromagnetic (EM) field of both linear and circular polarization. Within the framework of that model we derive exact analytical expressions for the cross sections of the one- and two-photon H- detachment processes in the lowest orders of perturbation theory on EM interaction of the detached electron with an ionizing field and studied the effect of various values of the problem parameters. We show that both obtained cross sections are in good agreement with the values measured in relevant experiments and the best results calculated by other authors with different (but much more sophisticated and complicated) approaches and methods.

  6. Performance of multi-aperture grid extraction systems for an ITER-relevant RF-driven negative hydrogen ion source

    NASA Astrophysics Data System (ADS)

    Franzen, P.; Gutser, R.; Fantz, U.; Kraus, W.; Falter, H.; Fröschle, M.; Heinemann, B.; McNeely, P.; Nocentini, R.; Riedl, R.; Stäbler, A.; Wünderlich, D.

    2011-07-01

    The ITER neutral beam system requires a negative hydrogen ion beam of 48 A with an energy of 0.87 MeV, and a negative deuterium beam of 40 A with an energy of 1 MeV. The beam is extracted from a large ion source of dimension 1.9 × 0.9 m2 by an acceleration system consisting of seven grids with 1280 apertures each. Currently, apertures with a diameter of 14 mm in the first grid are foreseen. In 2007, the IPP RF source was chosen as the ITER reference source due to its reduced maintenance compared with arc-driven sources and the successful development at the BATMAN test facility of being equipped with the small IPP prototype RF source ( {\\sim}\\frac{1}{8} of the area of the ITER NBI source). These results, however, were obtained with an extraction system with 8 mm diameter apertures. This paper reports on the comparison of the source performance at BATMAN of an ITER-relevant extraction system equipped with chamfered apertures with a 14 mm diameter and 8 mm diameter aperture extraction system. The most important result is that there is almost no difference in the achieved current density—being consistent with ion trajectory calculations—and the amount of co-extracted electrons. Furthermore, some aspects of the beam optics of both extraction systems are discussed.

  7. Global model analysis of negative ion generation in low-pressure inductively coupled hydrogen plasmas with bi-Maxwellian electron energy distributions

    SciTech Connect

    Huh, Sung-Ryul; Kim, Nam-Kyun; Jung, Bong-Ki; Chung, Kyoung-Jae; Hwang, Yong-Seok; Kim, Gon-Ho

    2015-03-15

    A global model was developed to investigate the densities of negative ions and the other species in a low-pressure inductively coupled hydrogen plasma with a bi-Maxwellian electron energy distribution. Compared to a Maxwellian plasma, bi-Maxwellian plasmas have higher populations of low-energy electrons and highly vibrationally excited hydrogen molecules that are generated efficiently by high-energy electrons. This leads to a higher reaction rate of the dissociative electron attachment responsible for negative ion production. The model indicated that the bi-Maxwellian electron energy distribution at low pressures is favorable for the creation of negative ions. In addition, the electron temperature, electron density, and negative ion density calculated using the model were compared with the experimental data. In the low-pressure regime, the model results of the bi-Maxwellian electron energy distributions agreed well quantitatively with the experimental measurements, unlike those of the assumed Maxwellian electron energy distributions that had discrepancies.

  8. Hydrogen negative ion production in a 14 GHz electron cyclotron resonance compact ion source with a cone-shaped magnetic filter

    SciTech Connect

    Ichikawa, T.; Kasuya, T.; Wada, M.; Kenmotsu, T.; Maeno, S.; Nishiura, M.; Shimozuma, T.; Yamaoka, H.

    2014-02-15

    The plasma electrode structure of a 14 GHz ECR ion source was modified to enlarge the plasma volume of low electron temperature region. The result shows that the extracted beam current reached about 0.6 mA/cm{sup 2} with about 40 W microwave power. To investigate the correlation between the volume of the low electron temperature region and the H{sup −} current, a vacuum ultraviolet (VUV) spectrometer had been installed to observe light emission in the VUV wavelength range from the plasma. From the results of the negative ion beam current and that from VUV spectrometry, production rate of vibrationally excited hydrogen molecule seems to be enhanced by increasing the volume of low electron temperature region.

  9. Hydrogen negative ion production in a 14 GHz electron cyclotron resonance compact ion source with a cone-shaped magnetic filter.

    PubMed

    Ichikawa, T; Kasuya, T; Kenmotsu, T; Maeno, S; Nishiura, M; Shimozuma, T; Yamaoka, H; Wada, M

    2014-02-01

    The plasma electrode structure of a 14 GHz ECR ion source was modified to enlarge the plasma volume of low electron temperature region. The result shows that the extracted beam current reached about 0.6 mA/cm(2) with about 40 W microwave power. To investigate the correlation between the volume of the low electron temperature region and the H(-) current, a vacuum ultraviolet (VUV) spectrometer had been installed to observe light emission in the VUV wavelength range from the plasma. From the results of the negative ion beam current and that from VUV spectrometry, production rate of vibrationally excited hydrogen molecule seems to be enhanced by increasing the volume of low electron temperature region.

  10. VUV emission spectroscopy diagnostics of a 14 GHz ECR negative hydrogen ion source

    SciTech Connect

    Tamura, R. Ichikawa, T.; Kasuya, T.; Wada, M.; Nishiura, M.; Shimozuma, T.

    2015-04-08

    Vacuum Ultra Violet(VUV) emission from a 4 cm diameter 2 cm long compact ion source excited by 14 GHz microwave has been investigated. Intensity ratio of band spectrum emission near Ly-α to Ly-α line spectrum is determined from the measured spectrum. which shows preferential excitation of molecules near the entrance of microwave input power. The ratio does not depend strongly upon pressure nor the input microwave power when the intensity is integrated over the volume of the plasma. The spatial distribution of the spectrum intensity ratio exhibits concentrations near microwave inlet and the opposite side where the microwave matching structure is located. The ratio at these peripheral regions is about two times as high as that of the central region. The ratio increased in proportion to the ion source pressure up to about 3.0 Pa, indicating efficient production of high energy electrons by ECR up to this pressure.

  11. Importance of electric field for H{sup -} extraction in a volume-type hydrogen negative ion source

    SciTech Connect

    Matsumoto, Y.; Nishiura, M.; Sasao, M.; Yamaoka, H.; Shinto, K.; Wada, M.

    2008-02-15

    The effect upon extraction of negative hydrogen ions (H{sup -}) due to electric field near the extractor hole of a H{sup -} source is studied experimentally and theoretically. Probe measurements show that the extraction electric field penetrates into the plasma in the region near the extractor hole. Based on this observation a three-dimensional H{sup -} trajectory calculation that takes into account the local electric field distribution near the plasma electrode has been carried out. The validity of the trajectory calculation was examined by comparing the results with experimentally measured changes in H{sup -} current detected by a Faraday cup due to irradiation of a pulse laser beam in the region close to the extractor hole. The calculation results qualitatively explain the changes in H{sup -} current observed in the experiment. The calculation results also predict that the amount of H{sup -} current passing through the extractor hole changes with the electric field: the penetration of the electric field substantially enhances the H{sup -} extraction current, because it produces an electric field to attract H{sup -} toward the extraction hole.

  12. Experimental Evaluation of a Negative Ion Source for a Heavy Ion Fusion Negative Ion Driver

    SciTech Connect

    Grisham, L. R.; Hahto, S. K.; Hahto, S. T.; Kwan, J. W.; Leung, K. N.

    2004-06-16

    Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photo-detached to neutrals. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm{sup 2} was obtained under the same conditions that gave 57 45 mA/cm{sup 2} of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that i s used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl{sup -} was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with the near-equivalence of the positive and negative ion currents, suggests that the plasma in this region was mostly an ion-ion plasma. The negative chlorine current density was relatively insensitive to pressure, and scaled linearly with RF power. If this linear scaling continues to hold at higher RF powers, it should permit current densities of 100 45 mA/cm{sup 2}, sufficient for present heavy ion fusion injector concepts. The effective ion temperatures of the positive and negative ions appeared to be similar and relatively low for a plasma source.

  13. Polarized negative ions

    SciTech Connect

    Haeberli, W.

    1981-04-01

    This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 ..mu..A can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited state (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 ..mu..A, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.

  14. Single element of the matrix source of negative hydrogen ions: Measurements of the extracted currents combined with diagnostics.

    PubMed

    Yordanov, D; Lishev, St; Shivarova, A

    2016-02-01

    Combining measurements of the extracted currents with probe and laser-photodetachment diagnostics, the study is an extension of recent tests of factors and gas-discharge conditions stimulating the extraction of volume produced negative ions. The experiment is in a single element of a rf source with the design of a matrix of small-radius inductively driven discharges. The results are for the electron and negative-ion densities, for the plasma potential and for the electronegativity in the vicinity of the plasma electrode as well as for the currents of the extracted negative ions and electrons. The plasma-electrode bias and the rf power have been varied. Necessity of a high bias to the plasma electrode and stable linear increase of the extracted currents with the rf power are the main conclusions.

  15. H{sup -} beam extraction from a cesium seeded field effect transistor based radio frequency negative hydrogen ion source

    SciTech Connect

    Ando, A.; Matsuno, T.; Funaoi, T.; Tanaka, N.; Tsumori, K.; Takeiri, Y.

    2012-02-15

    H{sup -} beam was successfully extracted from a cesium seeded ion source operated using a field effect transistor inverter power supply as a radio frequency (RF) wave source. High density hydrogen plasma more than 10{sup 19} m{sup -3} was obtained using an external type antenna with RF frequency of lower than 0.5 MHz. The source was isolated by an isolation transformer and H{sup -} ion beam was extracted from a single aperture. Acceleration current and extraction current increased with the increase of extraction voltage. Addition of a small amount of cesium vapor into the source enhanced the currents.

  16. Negative ion source

    DOEpatents

    Leung, K.N.; Ehlers, K.W.

    1982-08-06

    An ionization vessel is divided into an ionizing zone and an extraction zone by a magnetic filter. The magnetic filter prevents high-energy electrons from crossing from the ionizing zone to the extraction zone. A small positive voltage impressed on a plasma grid, located adjacent an extraction grid, positively biases the plasma in the extraction zone to thereby prevent positive ions from migrating from the ionizing zone to the extraction zone. Low-energy electrons, which would ordinarily be dragged by the positive ions into the extraction zone, are thereby prevented from being present in the extraction zone and being extracted along with negative ions by the extraction grid. Additional electrons are suppressed from the output flux using ExB drift provided by permanent magnets and the extractor grid electrical field.

  17. Negative ion source

    DOEpatents

    Leung, Ka-Ngo; Ehlers, Kenneth W.

    1984-01-01

    An ionization vessel is divided into an ionizing zone and an extraction zone by a magnetic filter. The magnetic filter prevents high-energy electrons from crossing from the ionizing zone to the extraction zone. A small positive voltage impressed on a plasma grid, located adjacent an extraction grid, positively biases the plasma in the extraction zone to thereby prevent positive ions from migrating from the ionizing zone to the extraction zone. Low-energy electrons, which would ordinarily be dragged by the positive ions into the extraction zone, are thereby prevented from being present in the extraction zone and being extracted along with negative ions by the extraction grid. Additional electrons are suppressed from the output flux using ExB drift provided by permanent magnets and the extractor grid electrical field.

  18. Negative ion source

    DOEpatents

    Leung, K.N.; Ehlers, K.W.

    1984-12-04

    An ionization vessel is divided into an ionizing zone and an extraction zone by a magnetic filter. The magnetic filter prevents high-energy electrons from crossing from the ionizing zone to the extraction zone. A small positive voltage impressed on a plasma grid, located adjacent an extraction grid, positively biases the plasma in the extraction zone to thereby prevent positive ions from migrating from the ionizing zone to the extraction zone. Low-energy electrons, which would ordinarily be dragged by the positive ions into the extraction zone, are thereby prevented from being present in the extraction zone and being extracted along with negative ions by the extraction grid. Additional electrons are suppressed from the output flux using ExB drift provided by permanent magnets and the extractor grid electrical field. 14 figs.

  19. Hydrogen ion microlithography

    DOEpatents

    Tsuo, Y. Simon; Deb, Satyen K.

    1990-01-01

    Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing.

  20. Hydrogen ion microlithography

    DOEpatents

    Tsuo, Y.S.; Deb, S.K.

    1990-10-02

    Disclosed is a hydrogen ion microlithography process for use in microelectronic fabrication and semiconductor device processing. The process comprises the steps of providing a single layer of either an amorphous silicon or hydrogenated amorphous silicon material. A pattern is recorded in a selected layer of amorphous silicon or hydrogenated amorphous silicon materials by preferentially implanting hydrogen ions therein so as to permit the selected layer to serve as a mask-resist wafer suitable for subsequent development and device fabrication. The layer is developed to provide a surface pattern therein adaptable for subsequent use in microelectronic fabrication and semiconductor device processing. 6 figs.

  1. Doppler shift measurement of Balmer-alpha line spectrum emission from a plasma in a negative hydrogen ion source

    SciTech Connect

    Wada, M. Doi, K.; Kisaki, M.; Nakano, H.; Tsumori, K.; Nishiura, M.

    2015-04-08

    Balmer-α light emission from the extraction region of the LHD one-third ion source has shown a characteristic Doppler broadening in the wavelength spectrum detected by a high resolution spectrometer. The spectrum resembles Gaussian distribution near the wavelength of the intensity peak, while it has an additional component of a broader foot. The measured broadening near the wavelength of the intensity peak corresponds to 0.6 eV hydrogen atom temperature. The spectrum exhibits a larger expansion in the blue wing which becomes smaller when the line of sight is tilted toward the driver region from the original observation axis parallel to the plasma grid. A surface collision simulation model predicts the possibility of hydrogen reflection at the plasma grid surface to form a broad Balmer-α light emission spectrum.

  2. Influence of electric field penetration by a three-electrode beam extraction system on hydrogen negative ion source plasma

    NASA Astrophysics Data System (ADS)

    Matsumoto, Y.; Nishiura, M.; Yamaoka, H.; Sasao, M.; Wada, M.

    2014-02-01

    We study influence of electric field penetration into H- ion source plasma with three-electrode beam extraction system. Clear change in the plasma potential due to the field penetration is observed in case of low gap voltage between a plasma electrode and an extraction electrode. Influence of lens voltage on the second electrode, which is normally utilized to focus the extracted beam, on ion source plasma is evaluated separating contributions of H- density in the plasma and extraction probability of H- ions from the plasma by two kinds of photodetachment techniques. In our operation condition, we found that the lens voltage is also useful to enhance the H- density in the plasma, though it negatively affects the extraction probability.

  3. Negative ion source

    DOEpatents

    Delmore, James E.

    1987-01-01

    A method and apparatus for providing a negative ion source accelerates electrons away from a hot filament electron emitter into a region of crossed electric and magnetic fields arranged in a magnetron configuration. During a portion of the resulting cycloidal path, the electron velocity is reduced below its initial value. The electron accelerates as it leaves the surface at a rate of only slightly less than if there were no magnetic field, thereby preventing a charge buildup at the surface of the emitter. As the electron traverses the cycloid, it is decelerated during the second, third, and fourth quadrants, then reeccelerated as it approaches the end of the fourth quadrant to regain its original velocity. The minimum velocity occurs during the fourth quadrant, and corresponds to an electron temperature of 200.degree. to 500.degree. for the electric and magnetic fields commonly encountered in the ion sources of magnetic sector mass spectrometers. An ion source using the above-described thermalized electrons is also disclosed.

  4. Expansion of a plasma across a transverse magnetic field in a negative hydrogen ion source for fusion

    NASA Astrophysics Data System (ADS)

    Fantz, Ursel; Schiesko, Loic; Wünderlich, Dirk

    2012-10-01

    Negative ion sources are a key component of the neutral beam injection systems for the international fusion experiment ITER. To achieve the required ion current of 40 A at a tolerable amount of co-extracted electrons (electron to ion ratio below one) the source is separated into a plasma generation region and an expansion chamber equipped with a magnetic filter field (up to 10 mT). The field is needed for: (1) cooling the electrons down and thus minimize the H^- destruction by collisions, (2) to reduce the co-extracted electron current, and (3) to enhance the extraction probability for the surface produced negative ions. The area of the ITER source will be approximately 1m width and 2 m height, the IPP prototype source is a 1/8-size source. The recently installed flexible magnetic filter frame allows for systematic filter field studies (strength, position, polarity). Two Langmuir probes have been used to measure the plasma parameters simultaneously in axial direction. The profiles in the upper and lower part of the expansion chamber show beside the expected electron temperature and density decrease a drop in the plasma potential and a drift depending on the polarity, which vanishes when removing the filter field. The data interpretation is supported by modeling activities.

  5. Negative Halogen Ions for Fusion Applications

    SciTech Connect

    Grisham, L.R.; Kwan, J.W.; Hahto, S.K.; Hahto, S.T.; Leung, K.N.; Westenskow, G.

    2006-01-01

    Over the past quarter century, advances in hydrogen negative ion sources have extended the usable range of hydrogen isotope neutral beams to energies suitable for large magnetically confined fusion devices. Recently, drawing upon this experience, negative halogen ions have been proposed as an alternative to positive ions for heavy ion fusion drivers in inertial confinement fusion, because electron accumulation would be prevented in negative ion beams, and if desired, the beams could be photo-detached to neutrals. This paper reports the results of an experiment comparing the current density and beam emittance of Cl+ and Cl- extracted from substantially ion-ion plasmas with that of Ar+ extracted from an ordinary electron-ion plasma, all using the same source, extractor, and emittance scanner. At similar discharge conditions, the Cl- current was typically 85 – 90% of the positive chlorine current, with an e-/ Cl- ratio as low as seven without grid magnets. The Cl- was as much as 76% of the Ar+ current from a discharge with the same RF drive. The minimum normalized beam emittance and inferred ion temperatures of Cl+, Cl-, and Ar+ were all similar, so the current density and optical quality of Cl- appear as suitable for heavy ion fusion driver applications as a positive noble gas ion of similar mass. Since F, I, and Br should all behave similarly in an ion source, they should also be suitable as driver beams.

  6. Experimental evaluation of a negative ion source for a heavy ionfusion negative ion driver

    SciTech Connect

    Grisham, L.R.; Hahto, S.K.; Hahto, S.T.; Kwan, J.W.; Leung, K.N.

    2005-01-18

    Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photodetached to neutrals [1,2,3]. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm{sup 2} was obtained under the same conditions that gave 57 mA/cm{sup 2} of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that is used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl{sup -} was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with the near-equivalence of the positive and negative ion currents, suggests that the plasma in this region was mostly an ion-ion plasma. The negative chlorine current density was relatively insensitive to pressure, and scaled linearly with RF power. If this linear scaling continues to hold at higher RF powers, it should permit current densities of 100 mA/cm{sup 2}, sufficient for present heavy ion fusion injector concepts. The effective ion temperatures of the positive and negative ions appeared to be similar and relatively low for a plasma source.

  7. Development of the front end test stand and vessel for extraction and source plasma analyses negative hydrogen ion sources at the Rutherford Appleton Laboratory

    SciTech Connect

    Lawrie, S. R.; Faircloth, D. C.; Letchford, A. P.; Perkins, M.; Whitehead, M. O.; Wood, T.; Gabor, C.; Back, J.

    2014-02-15

    The ISIS pulsed spallation neutron and muon facility at the Rutherford Appleton Laboratory (RAL) in the UK uses a Penning surface plasma negative hydrogen ion source. Upgrade options for the ISIS accelerator system demand a higher current, lower emittance beam with longer pulse lengths from the injector. The Front End Test Stand is being constructed at RAL to meet the upgrade requirements using a modified ISIS ion source. A new 10% duty cycle 25 kV pulsed extraction power supply has been commissioned and the first meter of 3 MeV radio frequency quadrupole has been delivered. Simultaneously, a Vessel for Extraction and Source Plasma Analyses is under construction in a new laboratory at RAL. The detailed measurements of the plasma and extracted beam characteristics will allow a radical overhaul of the transport optics, potentially yielding a simpler source configuration with greater output and lifetime.

  8. Volume production of negative ions in the reflex-type ion source

    SciTech Connect

    Jimbo, K.

    1982-06-01

    The production of negative hydrogen ions is investigated in the reflex-type negative ion source. The extracted negative hydrogen currents of 9.7 mA (100 mA/cm/sup 2/) for H/sup -/ and of 4.1 mA(42 mA/cm/sup 2/) for D/sup -/ are obtained continuously. The impurity is less than 1%. An isotope effect of negative ion production is observed.

  9. Extracted current saturation in negative ion sources

    SciTech Connect

    Mochalskyy, S.; Lifschitz, A. F.; Minea, T.

    2012-06-01

    The extraction of negatively charged particles from a negative ion source is one of the crucial issues in the development of the neutral beam injector system for future experimental reactor ITER. Full 3D electrostatic particle-in-cell Monte Carlo collision code - ONIX [S. Mochalskyy et al., Nucl. Fusion 50, 105011 (2010)] - is used to simulate the hydrogen plasma behaviour and the extracted particle features in the vicinity of the plasma grid, both sides of the aperture. It is found that the contribution to the extracted negative ion current of ions born in the volume is small compared with that of ions created at the plasma grid walls. The parametric study with respect to the rate of negative ions released from the walls shows an optimum rate. Beyond this optimum, a double layer builds-up by the negative ion charge density close to the grid aperture surface reducing thus extraction probability, and therefore the extracted current. The effect of the extraction potential and magnetic field magnitudes on the extraction is also discussed. Results are in good agreement with available experimental data.

  10. Three chamber negative ion source

    DOEpatents

    Leung, Ka-Ngo; Ehlers, Kenneth W.; Hiskes, John R.

    1985-01-01

    A negative ion vessel is divided into an excitation chamber, a negative ionization chamber and an extraction chamber by two magnetic filters. Input means introduces neutral molecules into a first chamber where a first electron discharge means vibrationally excites the molecules which migrate to a second chamber. In the second chamber a second electron discharge means ionizes the molecules, producing negative ions which are extracted into or by a third chamber. A first magnetic filter prevents high energy electrons from entering the negative ionization chamber from the excitation chamber. A second magnetic filter prevents high energy electrons from entering the extraction chamber from the negative ionizing chamber. An extraction grid at the end of the negative ion vessel attracts negative ions into the third chamber and accelerates them. Another grid, located adjacent to the extraction grid, carries a small positive voltage in order to inhibit positive ions from migrating into the extraction chamber and contour the plasma potential. Additional electrons can be suppressed from the output flux using ExB forces provided by magnetic field means and the extractor grid electric potential.

  11. Cesium injection system for negative ion duoplasmatrons

    DOEpatents

    Kobayashi, Maasaki; Prelec, Krsto; Sluyters, Theodorus J

    1978-01-01

    Longitudinally extending, foraminous cartridge means having a cylindrical side wall forming one flat, circular, tip end surface and an opposite end; an open-ended cavity, and uniformly spaced orifices for venting the cavity through the side wall in the annulus of a plasma ring for uniformly ejecting cesium for coating the flat, circular, surface. To this end, the cavity is filled with a cesium containing substance and attached to a heater in a hollow-discharge duoplasmatron. By coating the flat circular surface with a uniform monolayer of cesium and locating it in an electrical potential well at the end of a hollow-discharge, ion duoplasmatron source of an annular hydrogen plasma ring, the negative hydrogen production from the duoplasmatron is increased. The negative hydrogen is produced on the flat surface of the cartridge and extracted by the electrical potential well along a trajectory coaxial with the axis of the plasma ring.

  12. Sub microsecond notching of a negative hydrogen beam at low energy utilizing a magnetron ion source with a split extractor

    SciTech Connect

    Moehs, Douglas; /Fermilab

    2004-12-01

    A technique for sub-microsecond beam notching is being developed at 20 keV utilizing a Magnetron ion source with a slit extraction system and a split extractor. Each half of the extractor is treated as part of a 50 ohm transmission line which can be pulsed at {+-}700 volts creating a 1400 volt gradient. This system along with the associated electronics is electrically floated on top of a pulsed extraction voltage. A beam reduction of 95% has been observed at the end of the Fermilab 400 MeV Linac and 35% notching has recently been achieved in the Booster.

  13. Tunable negative Poisson's ratio in hydrogenated graphene.

    PubMed

    Jiang, Jin-Wu; Chang, Tienchong; Guo, Xingming

    2016-09-21

    We perform molecular dynamics simulations to investigate the effect of hydrogenation on the Poisson's ratio of graphene. It is found that the value of the Poisson's ratio of graphene can be effectively tuned from positive to negative by varying the percentage of hydrogenation. Specifically, the Poisson's ratio decreases with an increase in the percentage of hydrogenation, and reaches a minimum value of -0.04 when the percentage of hydrogenation is about 50%. The Poisson's ratio starts to increase upon a further increase of the percentage of hydrogenation. The appearance of a minimum negative Poisson's ratio in the hydrogenated graphene is attributed to the suppression of the hydrogenation-induced ripples during the stretching of graphene. Our results demonstrate that hydrogenation is a valuable approach for tuning the Poisson's ratio from positive to negative in graphene. PMID:27536878

  14. Evaluation of negative ion distribution changes by image processing diagnostic

    SciTech Connect

    Ikeda, K. Nakano, H.; Tsumori, K.; Kisaki, M.; Nagaoka, K.; Tokuzawa, T.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Geng, S.

    2015-04-08

    Distributions of hydrogen Balmer-α (H{sub α}) intensity and its reduction behavior close to a plasma grid (PG) surface have been observed by a spectrally selective imaging system in an arc discharge type negative hydrogen ion source in National Institute for Fusion Science. H{sub α} reduction indicates a reduction of negative hydrogen ions because the mutual neutralization process between H{sup +} and H{sup −} ions causes the dominant excitation process for H{sub α} emission in the rich H{sup −} condition such as in ionic plasma. We observed a significant change in H{sub α} reduction distribution due to change in the bias voltage, which is used to suppress the electron influx. Small H{sub α} reduction in higher bias is likely because the production of negative ions is suppressed by the potential difference between the plasma and PG surface.

  15. Investigations of negative and positive cesium ion species

    NASA Technical Reports Server (NTRS)

    Chanin, L. M.

    1978-01-01

    A direct test is provided of the hypothesis of negative ion creation at the anode or collector of a diode operating under conditions simulating a cesium thermionic converter. The experimental technique involves using direct ion sampling through the collector electrode with mass analysis using a quadrupole mass analyzer. Similar measurements are undertaken on positive ions extracted through the emitter electrode. Measurements were made on a variety of gases including pure cesium, helium-cesium mixtures and cesium-hydrogen as well as cesium-xenon mixtures. The gas additive was used primarily to aid in understanding the negative ion formation processes. Measurements were conducted using emitter (cathode) temperatures up to about 1000 F. The major negative ion identified through the collector was Cs(-) with minor negative ion peaks tentatively identified as H(-), H2(-), H3(-), He(-) and a mass 66. Positive ions detected were believed to be Cs(+), Cs2(+) and Cs3(+).

  16. Electric Potential Near The Extraction Region In Negative Ion Sources With Surface Produced Negative Ions

    SciTech Connect

    Fukano, A.; Hatayama, A.

    2011-09-26

    The potential distribution near the extraction region in negative ion sources for the plasma with the surface produced negative ions is studied analytically. The potential is derived analytically by using a plasma-sheath equation, where negative ions produced on the Plasma Grid (PG) surface are considered in addition to positive ions and electrons. A negative potential peak is formed in the sheath region near the PG surface for the case of strong surface production of negative ions or for low energy negative ions. Negative ions are reflected by the negative potential peak near the PG and returned to the PG surface. This reflection mechanism by the negative potential peak possibly becomes a factor in negative ion extraction. It is also indicated that the potential difference between the plasma region and the wall decreases by the surface produced negative ions. This also has the possibility to contribute to the negative ion extraction.

  17. 3D numerical simulations of negative hydrogen ion extraction using realistic plasma parameters, geometry of the extraction aperture and full 3D magnetic field map

    NASA Astrophysics Data System (ADS)

    Mochalskyy, S.; Wünderlich, D.; Ruf, B.; Franzen, P.; Fantz, U.; Minea, T.

    2014-02-01

    Decreasing the co-extracted electron current while simultaneously keeping negative ion (NI) current sufficiently high is a crucial issue on the development plasma source system for ITER Neutral Beam Injector. To support finding the best extraction conditions the 3D Particle-in-Cell Monte Carlo Collision electrostatic code ONIX (Orsay Negative Ion eXtraction) has been developed. Close collaboration with experiments and other numerical models allows performing realistic simulations with relevant input parameters: plasma properties, geometry of the extraction aperture, full 3D magnetic field map, etc. For the first time ONIX has been benchmarked with commercial positive ions tracing code KOBRA3D. A very good agreement in terms of the meniscus position and depth has been found. Simulation of NI extraction with different e/NI ratio in bulk plasma shows high relevance of the direct negative ion extraction from the surface produced NI in order to obtain extracted NI current as in the experimental results from BATMAN testbed.

  18. Application of anomalous diffusion in production of negative ions

    SciTech Connect

    Jimbo, K.

    1984-11-01

    The production of negative hydrogen ions is investigated in the reflex-type negative ion sources. When anomalous diffusion in the positive column was found by Hoh and Lehnert (Phys. Fluids 3, 600 (1960)), it was pointed out that the large particle loss produced by anomalous diffusion is compensated for by the larger particle production inside the plasma. In the present experiments anomalous diffusion was artificially encouraged by changing the radial electric field inside the reflex discharge. Apparent encouragement of negative ion current by the increase of the density fluctuation amplitude is observed. Twice as much negative ion current was obtained with the artificial encouragement as without. On the other hand, the larger extracted negative ion current was observed with a lower electron temperature, which is calculated from the anomalous diffusion coefficient derived from a simple nonlinear theory. This result is consistent with Wadehra's calculated results (Appl. Phys. Lett. 35, 917 (1979)).

  19. Simulation Based on Ion Propulsion Rocket System with Using Negative ion - Negative Ion Pair Techniques

    NASA Astrophysics Data System (ADS)

    Sathiyavel, C.

    2016-07-01

    Ion propulsion rocket system is expected to become popular with the development of ion-ion pair techniques because of their stimulated of low propellant, Design of Thrust range is 1N with low electric power and high efficiency. A Negative ion-Negative ion pair of ion propulsion rocket system is proposed in this work .Negative Ion Based Rocket system consists of three parts 1.ionization chamber 2. Repulsion force and ion accelerator 3. Exhaust of Nozzle. The Negative ions from electro negatively gas are produced by attachment of the gas ,such as chlorine with electron emitted from a Electron gun ionization chamber. The formulate of large stable negative ion is achievable in chlorine gas with respect to electron affinity (∆E). The electron affinity is a measure of the energy change when an electron is added to a neutral atom to form a negative ion. When a neutral chlorine atom in the gaseous form picks up an electron to form a Cl- ion, it releases energy of 349 kJ/mol or 3.6 ev/atom. It is said to have an electron affinity of -349 kJ/mol ,the negative sign indicating that energy is released during this process .The mechanisms of attachment involve the formation of intermediate states. In that reason for , the highly repulsive force created between the same negative ions. The distance between same negative ions is important for the evaluate of the rocket thrust and is also determined by the exhaust velocity of the propellant. The mass flow rate of propellant is achieved by the ratio of total mass of the propellant (Kg) needed for operation to time period(s). Accelerate the Negative ions to a high velocity in the thrust vector direction with a significantly intense Magnetic field and the exhaust of negative ions through Nozzle. The simulation of the ion propulsion system has been carried out by MATLAB. By comparing the simulation results with the theoretical and previous results, we have found that the proposed method is achieved of thrust value with estimated

  20. EDITORIAL: Negative ion based neutral beam injection

    NASA Astrophysics Data System (ADS)

    Hemsworth, R. S.

    2006-06-01

    It is widely recognized that neutral beam injection (NBI), i.e. the injection of high energy, high power, beams of H or D atoms, is a flexible and reliable system that has been the main heating system on a large variety of fusion devices, and NBI has been chosen as one of the three heating schemes of the International Tokomak Reactor (ITER). To date, all the NBI systems but two have been based on the neutralization (in a simple gas target) of positive hydrogen or deuterium ions accelerated to <100 keV/nucleon. Above that energy the neutralization of positive ions falls to unacceptably low values, and higher energy neutral beams have to be created by the neutralization of accelerated negative ions (in a simple gas target), as this remains high (approx60%) up to >1 MeV/nucleon. Unfortunately H- and D- are difficult to create, and the very characteristic that makes them attractive, the ease with which the electron is detached from the ion, means that it is difficult to create high concentrations or fluxes of them, and it is difficult to avoid substantial, collisional, losses in the extraction and acceleration processes. However, there has been impressive progress in negative ion sources and accelerators over the past decade, as demonstrated by the two pioneering, operational, multi-megawatt, negative ion based, NBI systems at LHD (180 keV, H0) and JT-60U (500 keV, D0), both in Japan. Nevertheless, the system proposed for ITER represents a substantial technological challenge as an increase is required in beam energy, to 1 MeV, D0, accelerated ion (D-) current, to 40 A, accelerated current density, 200 A m-2 of D-, and pulse length, to 1 h. At the Fourth IAEA Technical Meeting on Negative Ion Based Neutral Beam Injectors, hosted by the Consorzio RFX, Padova, Italy, 9-11 May 2005, the status of the R&D aimed at the realization of the injectors for ITER was presented. Because of the importance of this development to the success of the ITER project, participants at that

  1. Sputter process diagnostics by negative ions

    NASA Astrophysics Data System (ADS)

    Zeuner, Michael; Neumann, Horst; Zalman, Jan; Biederman, Hynek

    1998-05-01

    We measured the energy distributions of negative ions during reactive sputtering of silicon in oxygen. Various oxygen containing negative ions are formed in the cathode sheath or directly at the sputter target, respectively. These negative ions are accelerated away from the cathode by the electrical field, and can be detected using a mass spectrometer facing the sputter magnetron. The origin of each ion can be determined from peak structures in the energy distribution. Additionally the flux of different negative ions provides information on poisoning of the target by oxide films.

  2. Volume production of negative ions in the reflex type ion source

    SciTech Connect

    Jimbo, K.

    1982-01-01

    The production of negative hydrogen ions is investigated in the reflex-type negative ion source. The extracted negative hydrogen currents of 9.7 mA (100 mA/cm/sup 2/) for H/sup -/ and of 4.1 mA (42 mA/cm/sup 2/) for D/sup -/ are obtained continuously. The impurity is less then 1%. An isotope effect of negative ion production is observed. When anomalous diffusion in the positive column was found by Lehnert and Hoh (1960), it was pointed out that the large particle loss produced by anomalous diffusion is compensated by the large particle production inside the plasma, i.e., the plasma tries to maintain itself. The self-sustaining property of the plasma is applied to the reflex-type negative ion source. Anomalous diffusion was artificially encouraged by changing the radial electric field inside the reflex discharge. The apparent encouragement of negative ion diffusion by the increase of density fluctuation amplitude is observed. Twice as much negative ion current was obtained with the artificial encouragement as without. It is found from the quasilinear theory that the inwardly directed radial electric field destabilizes the plasma in the reflex-type ion source. The nonlinear theory based on Yoshikawa method (1962) is extended, and the anomalous diffusion coefficient in a weakly ionized plasma is obtained. The electrostatic sheath trap, which increases the confinement of negative ions in the reflex-type ion source, is also discussed.

  3. Ionization phenomena and sources of negative ions

    SciTech Connect

    Alton, G.D.

    1983-01-01

    Negative ion source technology has rapidly advanced during the past several years as a direct consequence of the discovery of Krohn that negative ion yields can be greatly enhanced by sputtering in the presence of Group IA elements. Today, most negative ion sources use this discovery directly or the principles implied to effect negative ion formation through surface ionization. As a consequence, the more traditional direct extraction plasma and charge exchange sources are being used less frequently. However, the charge exchange generation mechanism appears to be as universal, is very competitive in terms of efficiency and has the advantage in terms of metastable ion formation. In this review, an attempt has been made to briefly describe the principal processes involved in negative ion formation and sources which are representative of a particular principle. The reader is referred to the literature for specific details concerning the operational characteristics, emittances, brightnesses, species and intensity capabilities of particular sources. 100 references.

  4. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  5. Charged particle flows in the beam extraction region of a negative ion source for NBI.

    PubMed

    Geng, S; Tsumori, K; Nakano, H; Kisaki, M; Ikeda, K; Osakabe, M; Nagaoka, K; Takeiri, Y; Shibuya, M; Kaneko, O

    2016-02-01

    Experiments by a four-pin probe and photodetachment technique were carried out to investigate the charged particle flows in the beam extraction region of a negative hydrogen ion source for neutral beam injector. Electron and positive ion flows were obtained from the polar distribution of the probe saturation current. Negative hydrogen ion flow velocity and temperature were obtained by comparing the recovery times of the photodetachment signals at opposite probe tips. Electron and positive ions flows are dominated by crossed field drift and ambipolar diffusion. Negative hydrogen ion temperature is evaluated to be 0.12 eV. PMID:26931985

  6. Negative ion spectrometry for detecting nitrated explosives

    NASA Technical Reports Server (NTRS)

    Boettger, H. G.; Yinon, J.

    1975-01-01

    Ionization procedure is modified to produce mainly negative ions by electron capture. Peaks of negative ions are monitored conventionally. Nitrated organic materials could be identified directly from sample sniff inlet stream by suitably modified mass spectrometer because of unique electronegativity which nitro group imparts to organic material.

  7. Negative ion kinetics in RF glow discharges

    SciTech Connect

    Gottscho, R.A.; Gacbe, C.E.

    1986-04-01

    Using temporally and spatially resolved laser spectroscopy, the authors have determined the identities, approximate concentrations, effects on the local field, and kinetics of formation and loss of negative ions in RF discharges. CI/sup -/ and BCI/sub 3//sup -/ are the dominant negative ions found in low-frequency discharges through CI/sub 2/ and BCI/sub 3/, respectively. The electron affinity for CI is measured to be 3.6118 +- 0.0005 eV. Negative ion kinetics are strongly affected by application of the RF field. Formation of negative ions by attachment of slow electrons in RF discharges is governed by the extent and duration of electron energy relaxation. Similarly, destruction of negative ions by collisional detachment and field extraction is dependent upon ion energy modulation. Thus, at low frequency, the anion density peaks at the beginning of the anodic and cathodic half-cycles after electrons have attached but before detachment and extraction have had time to occur. At higher frequencies, electrons have insufficient time to attach before they are reheated and the instantaneous anion density in the sheath is greatly reduced. When the negative ion density is comparable to the positive ion density, the plasma potential is observed to lie below the anode potential, double layers form between sheath and plasma, and anions and electrons are accelerated by large sheath fields to electrode surfaces.

  8. Negative air ions as a source of superoxide

    NASA Astrophysics Data System (ADS)

    Goldstein, Naum I.; Goldstein, Roman N.; Merzlyak, Mark N.

    1992-06-01

    The physico-chemical characteristics and possible formation mechanisms of negative air ions are considered. It was found that the products of oxygen and nitrogen negative ionization reduce ferricytochrome c and nitroblue tetrazolium, and that these reactions were inhibited by superoxide dismutase. The interaction of negatively ionized oxygen with water led to hydrogen peroxide accumulation, which was inhibited by tetranitromethane or catalase. Nitrogen ionization under these conditions caused the formation of the hydrated electron e{aq/—} and the superoxide anion O{2/—}. The data obtained indicate that the biological activity of negative air ions may be dependent on superoxide. The generation of reactive oxygen ions in the gas phase and also at a gas/water interface is described. A scheme for superoxide production under oxygen and nitrogen ionization is proposed.

  9. Negative and positive cesium ion studies

    NASA Technical Reports Server (NTRS)

    Kuehn, D. G.; Sutliff, D. E.; Chanin, L. M.

    1978-01-01

    Mass spectrometric analyses have been performed on the positive and negative species from discharges in Cs, He-Cs, and He-H2-Cs mixtures. Sampling was conducted through the electrodes of normal glow discharges and from close-spaced heated-cathode conditions, which approximate a cesium thermionic converter. No negative Cs ions were observed for Cs pressures less than .01 torr. Identified species included Cs(+), Cs2(+), Cs(-), and what appeared to be multiply charged ions. Low-mass negative and positive ions attributed to H2 were observed when an He-H2 mixture was also present in the discharge region.

  10. Negative electrodes for Na-ion batteries.

    PubMed

    Dahbi, Mouad; Yabuuchi, Naoaki; Kubota, Kei; Tokiwa, Kazuyasu; Komaba, Shinichi

    2014-08-01

    Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, current collectors, electrolytes and electrode/electrolyte interphase and its stabilization are essential for long cycle life Na-ion batteries. This paper also addresses the prospect of Na-ion batteries as low-cost and long-life batteries with relatively high-energy density as their potential competitive edge over the commercialized Li-ion batteries.

  11. The negative ions emission in nitrogen

    NASA Technical Reports Server (NTRS)

    Soon, W. H.; Kunc, J. A.

    1991-01-01

    The contribution of negative atomic ions to continuum radiation in nitrogen plasma is discussed. It is shown that both unstable N(-)(3P) and metastable N(-)(1D) ions have a significant effect on the total production of the continuum radiation at electron temperatures below 12,000 K.

  12. Negative Ions for Emerging Interdisciplinary Applications

    SciTech Connect

    Guharay, Samar K.

    2011-09-26

    In many applications related to ion beam-materials interactions negative ions are particularly desirable due to its merit to yield a very low surface charge-up voltage, {approx} a few volts, for both electrically isolated surfaces and insulators. Some important applications pertaining to ion beam-material interactions include surface analysis by secondary ion mass spectrometry (SIMS), voltage-contrast microscopy for semiconductor device inspection, materials processing, and ion beam lithography. These applications primarily require vacuum environments. On the other hand, a distinct area of activities constitutes formation of ions and ion transport in ambient environmental conditions, i.e., at atmospheric pressures. In this context, ion mobility spectrometry (IMS) is an important analytical device that uses negative ions and operates at ambient conditions. IMS is widely used in both physical and biological sciences including monitoring environmental conditions, security screening and disease detection. This article highlights several critical issues related to the ionization sources and ion transport in IMS. Additionally, the critical issues related to ion sources, transport and focusing are discussed in the context of SIMS with sub-micrometer spatial resolution.

  13. Efficient cesiation in RF driven surface plasma negative ion source.

    PubMed

    Belchenko, Yu; Ivanov, A; Konstantinov, S; Sanin, A; Sotnikov, O

    2016-02-01

    Experiments on hydrogen negative ions production in the large radio-frequency negative ion source with cesium seed are described. The system of directed cesium deposition to the plasma grid periphery was used. The small cesium seed (∼0.5 G) provides an enhanced H(-) production during a 2 month long experimental cycle. The gradual increase of negative ion yield during the long-term source runs was observed after cesium addition to the source. The degraded H(-) production was recorded after air filling to the source or after the cesium washing away from the driver and plasma chamber walls. The following source conditioning by beam shots produces the gradual recovery of H(-) yield to the high value. The effect of H(-) yield recovery after cesium coverage passivation by air fill was studied. The concept of cesium coverage replenishment and of H(-) yield recovery due to sputtering of cesium from the deteriorated layers is discussed. PMID:26932015

  14. Cytoplasmic hydrogen ion diffusion coefficient.

    PubMed Central

    al-Baldawi, N F; Abercrombie, R F

    1992-01-01

    The apparent cytoplasmic proton diffusion coefficient was measured using pH electrodes and samples of cytoplasm extracted from the giant neuron of a marine invertebrate. By suddenly changing the pH at one surface of the sample and recording the relaxation of pH within the sample, an apparent diffusion coefficient of 1.4 +/- 0.5 x 10(-6) cm2/s (N = 7) was measured in the acidic or neutral range of pH (6.0-7.2). This value is approximately 5x lower than the diffusion coefficient of the mobile pH buffers (approximately 8 x 10(-6) cm2/s) and approximately 68x lower than the diffusion coefficient of the hydronium ion (93 x 10(-6) cm2/s). A mobile pH buffer (approximately 15% of the buffering power) and an immobile buffer (approximately 85% of the buffering power) could quantitatively account for the results at acidic or neutral pH. At alkaline pH (8.2-8.6), the apparent proton diffusion coefficient increased to 4.1 +/- 0.8 x 10(-6) cm2/s (N = 7). This larger diffusion coefficient at alkaline pH could be explained quantitatively by the enhanced buffering power of the mobile amino acids. Under the conditions of these experiments, it is unlikely that hydroxide movement influences the apparent hydrogen ion diffusion coefficient. PMID:1617134

  15. Negative Electrodes for Li-Ion Batteries

    SciTech Connect

    Kinoshita, Kim; Zaghib, Karim

    2001-10-01

    Graphitized carbons have played a key role in the successful commercialization of Li-ion batteries. The physicochemical properties of carbon cover a wide range; therefore identifying the optimum active electrode material can be time consuming. The significant physical properties of negative electrodes for Li-ion batteries are summarized, and the relationship of these properties to their electrochemical performance in nonaqueous electrolytes, are discussed in this paper.

  16. Kinetics and continuum emission of negative atomic ions in partially ionized plasmas

    NASA Technical Reports Server (NTRS)

    Soon, W. H.; Kunc, J. A.

    1991-01-01

    Kinetics and continuum emission of negative ions are studied in stationary atomic hydrogen, nitrogen, and oxygen plasmas. The intensity of the negative-ion emission was found to be neglibible when compared to those of bound-bound and free-bound emission at low and medium particle densities. However, the negative-ion continuum emission can contribute significantly in certain parts of the emission spectrum at high particle densities.

  17. The production and destruction of negative ions

    SciTech Connect

    Pegg, D.J.

    1993-01-01

    Single photon absorption-single electron detachment from few-electron atomic negative ions was studied. A crossed beam apparatus is being used to perform energy- and angle-resolved photoelectron spectroscopic measurements following photodetachment. Forward-directed electrons were collected and energy analyzed. The kinetic energies and yields of the photoelectrons were obtained by fitting the spectral peaks to Gaussian functions. Electron affinities, asymmetry parameters and cross sections are determined from these measurements. A ratio method in which the cross section for the ion of interest is measured relative to that of a reference ion was used. The study of the photodetachment of Li[sup [minus

  18. Energetic beams of negative and neutral hydrogen from intense laser plasma interaction

    SciTech Connect

    Abicht, F.; Priebe, G.; Braenzel, J.; Schnürer, M.; Prasad, R.; Borghesi, M.; Andreev, A.; Nickles, P. V.; Jequier, S.; Revet, G.; Tikhonchuk, V.; Ter-Avetisyan, S.

    2013-12-16

    We present observations of intense beams of energetic negative hydrogen ions and fast neutral hydrogen atoms in intense (5 × 10{sup 19} W/cm{sup 2}) laser plasma interaction experiments, which were quantified in numerical calculations. Generation of negative ions and neutral atoms is ascribed to the processes of electron capture and loss by a laser accelerated positive ion in the collisions with a cloud of droplets. A comparison with a numerical model of charge exchange processes provides information on the cross section of the electron capture in the high energy domain.

  19. Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy, and Related Fields

    SciTech Connect

    Grisham, L.R.; Kwan, J.W.

    2008-08-01

    Some years ago it was suggested that halogen negative ions [1]could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons -- can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion-ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

  20. Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy,and Related Fields

    SciTech Connect

    Grisham, L. R.; Kwan, J. W.

    2008-08-01

    Some years ago it was suggested that halogen negative ions could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons - can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion - ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

  1. Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy, and Related Fields

    SciTech Connect

    L. Grisham and J.W. Kwan

    2008-08-12

    Some years ago it was suggested that halogen negative ions [1] could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons -- can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion-ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

  2. Cesium Delivery System for Negative Ion Source at IPR

    SciTech Connect

    Bansal, G.; Pandya, K.; Soni, J.; Gahlaut, A.; Parmar, K. G.; Bandyopadhyay, M.; Chakraborty, A.; Singh, M. J.

    2011-09-26

    The technique of surface production of negative ions using cesium, Cs, has been efficiently exploited over the years for producing negative ion beams with increased current densities from negative ion sources used on neutral beam lines. Deposition of Cs on the source walls and the plasma grid lowers the work function and therefore enables a higher yield of H{sup -}, when hydrogen particles (H and/or H{sub x}{sup +}) strike these surfaces.A single driver RF based (100 kW, 1 MHz) negative ion source test bed, ROBIN, is being set up at IPR under a technical collaboration between IPR and IPP, Germany. The optimization of the Cs oven design to be used on this facility as well as multidriver sources is underway. The characterization experiments of such a Cs delivery system with a 1 g Cs inventory have been carried out using surface ionization technique. The experiments have been carried by delivering Cs into a vacuum chamber without plasma. The linear motion of the surface ionization detector, SID, attached with a linear motion feedthrough allows measuring the angular distribution of the Cs coming out of the oven. Based on the experimental results, a Cs oven for ROBIN has been proposed. The Cs oven design and experimental results of the prototype Cs oven are reported and discussed in the paper.

  3. Negative ion beam generation in laser plasma interactions

    NASA Astrophysics Data System (ADS)

    Jequier, Sophie; Tikhonchuk, Vladimir; Ter-Avetisyan, Sargis

    2013-10-01

    Detection of a large number of energetic negative ions and neutral atoms have been reported in recent intense laser plasma interaction experiments. These particles were produced from fast positive ions (proton, carbon, oxygen) accelerated from a laser produced plasma when they were passing through a cold spray of water or ethanol. The negative ions formation is strongly related to the fast positive ions, and it is explained by a process of a single electron capture - loss. Double charge exchange, elastic scattering and energy loss phenomena have been neglected since their cross sections are much smaller. Assuming independent atoms approximation, we study populations evolution through the interaction zone analytically and numerically by solving the rate equations using cross sections drawn from literature. Taking into account the energy distribution of the incident ions, the calculations give the final energy distribution for the different species that can be compared to experimental spectra. First results obtained for hydrogen in the water case indicate that this model can explain the main observed features. The results concerning the carbon and oxygen ions will be also presented as well as refinement of the cross sections since some cross sections are missing for these energies.

  4. Historical Development of the Hydrogen Ion Concept

    ERIC Educational Resources Information Center

    Moore, Carl E.; Jaselskis, Bruno; Florian, Jan

    2010-01-01

    The concept of a positive hydrogen entity, later called the hydrogen ion and proton, seems to have started with Theodor von Grotthuss in 1805. The conception proposed by von Grotthuss has evolved via the works of many scientists; especially the contributions of Justus Liebig, Svante Arrhenius, S. P. L. Sorensen, I. M. Kolthoff, and R. P. Bell.…

  5. Development of versatile multiaperture negative ion sources

    SciTech Connect

    Cavenago, M.; Minarello, A.; Sattin, M.; Serianni, G.; Antoni, V.; Bigi, M.; Pasqualotto, R.; Recchia, M.; Veltri, P.; Agostinetti, P.; Barbisan, M.; Baseggio, L.; Cervaro, V.; Degli Agostini, F.; Franchin, L.; Laterza, B.; Ravarotto, D.; Rossetto, F.; Zaniol, B.; Zucchetti, S.; and others

    2015-04-08

    Enhancement of negative ion sources for production of large ion beams is a very active research field nowadays, driven from demand of plasma heating in nuclear fusion devices and accelerator applications. As a versatile test bench, the ion source NIO1 (Negative Ion Optimization 1) is being commissioned by Consorzio RFX and INFN. The nominal beam current of 135 mA at −60 kV is divided into 9 beamlets, with multiaperture extraction electrodes. The plasma is sustained by a 2 MHz radiofrequency power supply, with a standard matching box. A High Voltage Deck (HVD) placed inside the lead shielding surrounding NIO1 contains the radiofrequency generator, the gas control, electronics and power supplies for the ion source. An autonomous closed circuit water cooling system was installed for the whole system, with a branch towards the HVD, using carefully optimized helical tubing. Insulation transformer is installed in a nearby box. Tests of several magnetic configurations can be performed. Status of experiments, measured spectra and plasma luminosity are described. Upgrades of magnetic filter, beam calorimeter and extraction grid and related theoretical issues are reviewed.

  6. Development of versatile multiaperture negative ion sources

    NASA Astrophysics Data System (ADS)

    Cavenago, M.; Serianni, G.; Antoni, V.; Bigi, M.; De Muri, M.; Pasqualotto, R.; Recchia, M.; Veltri, P.; Agostinetti, P.; Barbisan, M.; Baseggio, L.; Cervaro, V.; Cazzador, M.; Degli Agostini, F.; Franchin, L.; Kulevoy, T.; Laterza, B.; Mimo, A.; Minarello, A.; Petrenko, S.; Ravarotto, D.; Rossetto, F.; Sattin, M.; Zaniol, B.; Zucchetti, S.

    2015-04-01

    Enhancement of negative ion sources for production of large ion beams is a very active research field nowadays, driven from demand of plasma heating in nuclear fusion devices and accelerator applications. As a versatile test bench, the ion source NIO1 (Negative Ion Optimization 1) is being commissioned by Consorzio RFX and INFN. The nominal beam current of 135 mA at -60 kV is divided into 9 beamlets, with multiaperture extraction electrodes. The plasma is sustained by a 2 MHz radiofrequency power supply, with a standard matching box. A High Voltage Deck (HVD) placed inside the lead shielding surrounding NIO1 contains the radiofrequency generator, the gas control, electronics and power supplies for the ion source. An autonomous closed circuit water cooling system was installed for the whole system, with a branch towards the HVD, using carefully optimized helical tubing. Insulation transformer is installed in a nearby box. Tests of several magnetic configurations can be performed. Status of experiments, measured spectra and plasma luminosity are described. Upgrades of magnetic filter, beam calorimeter and extraction grid and related theoretical issues are reviewed.

  7. Negative ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Hahto, Sami K.; Hahto, Sari T.

    2007-02-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source. A converter can be included in the ion source to produce negative ions.

  8. New types of negative ion sources

    SciTech Connect

    Borisko, V.N.; Lapshin, V.I.

    1995-12-31

    The plasma sources of negative ions which were elaborated in Kharkov State University are considered in this paper. These sources use the mechanism of dissociative stick of electrons with low energies to molecules of a working gas. The effective work of such sources needs a special system of low energy electrons formation. The effect of secondary electron emission used in negative ion sources is considered. The electrode material with a great coefficient of secondary electron emission allows one to obtain a few slow electrons per one bombarding electron. A plasma of Penning discharge is an emitter of initial elections. The electron electromagnetic trap in the secondary electron emission region allows one to enlarge volume of interaction of low energy electrons with the working gas molecules. The lifetime of slow electrons grows in this trap.

  9. Negative ion production and beam extraction processes in a large ion source (invited).

    PubMed

    Tsumori, K; Ikeda, K; Nakano, H; Kisaki, M; Geng, S; Wada, M; Sasaki, K; Nishiyama, S; Goto, M; Serianni, G; Agostinetti, P; Sartori, E; Brombin, M; Veltri, P; Wimmer, C; Nagaoka, K; Osakabe, M; Takeiri, Y; Kaneko, O

    2016-02-01

    Recent research results on negative-ion-rich plasmas in a large negative ion source have been reviewed. Spatial density and flow distributions of negative hydrogen ions (H(-)) and positive hydrogen ions together with those of electrons are investigated with a 4-pin probe and a photodetachment (PD) signal of a Langmuir probe. The PD signal is converted to local H(-) density from signal calibration to a scanning cavity ring down PD measurement. Introduction of Cs changes the slope of plasma potential local distribution depending upon the plasma grid bias. A higher electron density H2 plasma locally shields the bias potential and behaves like a metallic free electron gas. On the other hand, the bias and extraction electric fields penetrate in a Cs-seeded electronegative plasma even when the electron density is similar. Electrons are transported by the penetrated electric fields from the driver region along and across the filter and electron deflection magnetic fields. Plasma ions exhibited a completely different response against the penetration of electric fields. PMID:26932108

  10. Negative ion production and beam extraction processes in a large ion source (invited)

    NASA Astrophysics Data System (ADS)

    Tsumori, K.; Ikeda, K.; Nakano, H.; Kisaki, M.; Geng, S.; Wada, M.; Sasaki, K.; Nishiyama, S.; Goto, M.; Serianni, G.; Agostinetti, P.; Sartori, E.; Brombin, M.; Veltri, P.; Wimmer, C.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.

    2016-02-01

    Recent research results on negative-ion-rich plasmas in a large negative ion source have been reviewed. Spatial density and flow distributions of negative hydrogen ions (H-) and positive hydrogen ions together with those of electrons are investigated with a 4-pin probe and a photodetachment (PD) signal of a Langmuir probe. The PD signal is converted to local H- density from signal calibration to a scanning cavity ring down PD measurement. Introduction of Cs changes the slope of plasma potential local distribution depending upon the plasma grid bias. A higher electron density H2 plasma locally shields the bias potential and behaves like a metallic free electron gas. On the other hand, the bias and extraction electric fields penetrate in a Cs-seeded electronegative plasma even when the electron density is similar. Electrons are transported by the penetrated electric fields from the driver region along and across the filter and electron deflection magnetic fields. Plasma ions exhibited a completely different response against the penetration of electric fields.

  11. First experiments with the negative ion source NIO1.

    PubMed

    Cavenago, M; Serianni, G; De Muri, M; Agostinetti, P; Antoni, V; Baltador, C; Barbisan, M; Baseggio, L; Bigi, M; Cervaro, V; Degli Agostini, F; Fagotti, E; Kulevoy, T; Ippolito, N; Laterza, B; Minarello, A; Maniero, M; Pasqualotto, R; Petrenko, S; Poggi, M; Ravarotto, D; Recchia, M; Sartori, E; Sattin, M; Sonato, P; Taccogna, F; Variale, V; Veltri, P; Zaniol, B; Zanotto, L; Zucchetti, S

    2016-02-01

    Neutral Beam Injectors (NBIs), which need to be strongly optimized in the perspective of DEMO reactor, request a thorough understanding of the negative ion source used and of the multi-beamlet optics. A relatively compact radio frequency (rf) ion source, named NIO1 (Negative Ion Optimization 1), with 9 beam apertures for a total H(-) current of 130 mA, 60 kV acceleration voltage, was installed at Consorzio RFX, including a high voltage deck and an X-ray shield, to provide a test bench for source optimizations for activities in support to the ITER NBI test facility. NIO1 status and plasma experiments both with air and with hydrogen as filling gas are described. Transition from a weak plasma to an inductively coupled plasma is clearly evident for the former gas and may be triggered by rising the rf power (over 0.5 kW) at low pressure (equal or below 2 Pa). Transition in hydrogen plasma requires more rf power (over 1.5 kW). PMID:26932048

  12. 3D modelling of negative ion extraction from a negative ion source

    NASA Astrophysics Data System (ADS)

    Mochalskyy, S.; Lifschitz, A. F.; Minea, T.

    2010-10-01

    The development of a suitable negative ion source constitutes a crucial step in the construction of the neutral beam injector of ITER. To fulfil the ITER requirements in terms of heating and current drive, the negative ion source should deliver 40 A of D-. The achievement of such a source constitutes a technical and scientific challenge, and it requires a deeper understanding of the underlying physics of the source. The present knowledge of the ion extraction mechanism from the negative ion source is limited. It constitutes a complex problem that involves understanding the behaviour of magnetized plasma sheaths when negative ions and electrons are pulled out from the plasma. Moreover, due to the asymmetry induced by the crossed magnetic configuration used to filter the electrons, any realistic study of this problem must consider the three spatial dimensions. To address this problem in a realistic way, a 3D particles-in-cell electrostatic code specifically designed for this system was developed. The code uses a Cartesian coordinate system and it can deal with complex boundary geometry as it is the case of the extraction apertures (Hemsworth et al 2009 Nucl. Fusion 49 045006). The complex magnetic field that is applied to deflect electrons is also taken into account. This code, called ONIX, was used to investigate the plasma properties and the transport of negative ions and electrons close to a source extraction aperture. Results in the collisionless approach on the formation of the plasma meniscus and the screening of the extraction field by the plasma are presented here, as well as negative ions trajectories. Negative ion extraction efficiency from volume and surfaces is discussed.

  13. Calibrating the DARHT Electron Spectrometer with Negative Ions

    SciTech Connect

    R. Trainham , A. P. Tipton , and R. R. Bartech

    2005-11-01

    Negative ions of hydrogen and oxygen have been used to calibrate the DARHT electron spectrometer over the momentum range of 2 to 20 MeV/c. The calibration was performed on September 1, 3, and 8, 2004, and it is good to 0.5% absolute, provided that instrument alignment is carefully controlled. The momentum in MeV/c as a function of magnetic field (B in Gauss) and position in the detector plane (X in mm) is: P = (B-6.28)/(108.404-0.1935*X)

  14. Negative ion source with low temperature transverse divergence optical system

    DOEpatents

    Whealton, John H.; Stirling, William L.

    1986-01-01

    A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

  15. Negative ion source with low temperature transverse divergence optical system

    DOEpatents

    Whealton, J.H.; Stirling, W.L.

    1985-03-04

    A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

  16. On the formation and destruction of chlorine negative ions in the D region

    NASA Technical Reports Server (NTRS)

    Turco, R. P.

    1977-01-01

    We have investigated the possible reactions of chlorine atoms, chlorine monoxide, and hydrogen chloride with D region negative ions. The mesospheric concentrations of the neutral chlorine gases have been predicted with a diurnally varying one-dimensional model of the upper atmosphere. Despite the low abundances of chlorine compounds in air their high reactivity leads to the formation of substantial quantities of clorine negative ions at high altitudes. The concentration of chlorine ions is limited in daylight by rapid reactions with oxygen and hydrogen atoms and at night by the competitive production of other stable ions. The presence of chlorine negative ions in the upper atmosphere is consistent with in situ mass spectrometer observations of charged species. The abundance of chlorinated ions in the D region may be correlated with mesospheric nitric oxide and water vapor concentrations.

  17. Negative Ion Photoelectron Spectra of Halomethyl Anions

    NASA Astrophysics Data System (ADS)

    Vogelhuber, Kristen M.; Wren, Scott W.; McCoy, Anne B.; Ervin, Kent M.; Lineberger, W. Carl

    2009-06-01

    Halomethyl anions undergo a significant geometry change upon electron photodetachment, resulting in multiple extended vibrational progressions in the photoelectron spectra. The normal mode analysis that successfully models photoelectron spectra when geometry changes are modest is unable to reproduce the experimental data using physically reasonable parameters. A three-dimensional anharmonic coupled-mode analysis was employed to accurately reproduce the observed vibrational structure. We present the 364 nm negative ion photoelectron spectra of the halomethyl anions CHX_2^- and CDX_2^- (X = Cl, Br, I) and report electron affinities, vibrational frequencies, and geometries.

  18. Electron-less negative ion extraction from ion-ion plasmas

    SciTech Connect

    Rafalskyi, Dmytro; Aanesland, Ane

    2015-03-09

    This paper presents experimental results showing that continuous negative ion extraction, without co-extracted electrons, is possible from highly electronegative SF{sub 6} ion-ion plasma at low gas pressure (1 mTorr). The ratio between the negative ion and electron densities is more than 3000 in the vicinity of the two-grid extraction and acceleration system. The measurements are conducted by both magnetized and non-magnetized energy analyzers attached to the external grid. With these two analyzers, we show that the extracted negative ion flux is almost electron-free and has the same magnitude as the positive ion flux extracted and accelerated when the grids are biased oppositely. The results presented here can be used for validation of numerical and analytical models of ion extraction from ion-ion plasma.

  19. Noise reduction in negative-ion quadrupole mass spectrometry

    DOEpatents

    Chastagner, P.

    1993-04-20

    A quadrupole mass spectrometer (QMS) system is described having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.

  20. Noise reduction in negative-ion quadrupole mass spectrometry

    DOEpatents

    Chastagner, Philippe

    1993-01-01

    A quadrupole mass spectrometer (QMS) system having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.

  1. 2D accelerator design for SITEX negative ion source

    SciTech Connect

    Whealton, J.H.; Raridon, R.J.; McGaffey, R.W.; McCollough, D.H.; Stirling, W.L.; Dagenhart, W.K.

    1983-01-01

    Solving the Poisson-Vlasov equations where the magnetic field, B, is assumed constant, we optimize the optical system of a SITEX negative ion source in infinite slot geometry. Algorithms designed to solve the above equations were modified to include the curved emitter boundary data appropriate to a negative ion source. Other configurations relevant to negative ion sources are examined.

  2. Role of positive ions on the surface production of negative ions in a fusion plasma reactor type negative ion source—Insights from a three dimensional particle-in-cell Monte Carlo collisions model

    SciTech Connect

    Fubiani, G.; Boeuf, J. P.

    2013-11-15

    Results from a 3D self-consistent Particle-In-Cell Monte Carlo Collisions (PIC MCC) model of a high power fusion-type negative ion source are presented for the first time. The model is used to calculate the plasma characteristics of the ITER prototype BATMAN ion source developed in Garching. Special emphasis is put on the production of negative ions on the plasma grid surface. The question of the relative roles of the impact of neutral hydrogen atoms and positive ions on the cesiated grid surface has attracted much attention recently and the 3D PIC MCC model is used to address this question. The results show that the production of negative ions by positive ion impact on the plasma grid is small with respect to the production by atomic hydrogen or deuterium bombardment (less than 10%)

  3. Role of positive ions on the surface production of negative ions in a fusion plasma reactor type negative ion source--Insights from a three dimensional particle-in-cell Monte Carlo collisions model

    NASA Astrophysics Data System (ADS)

    Fubiani, G.; Boeuf, J. P.

    2013-11-01

    Results from a 3D self-consistent Particle-In-Cell Monte Carlo Collisions (PIC MCC) model of a high power fusion-type negative ion source are presented for the first time. The model is used to calculate the plasma characteristics of the ITER prototype BATMAN ion source developed in Garching. Special emphasis is put on the production of negative ions on the plasma grid surface. The question of the relative roles of the impact of neutral hydrogen atoms and positive ions on the cesiated grid surface has attracted much attention recently and the 3D PIC MCC model is used to address this question. The results show that the production of negative ions by positive ion impact on the plasma grid is small with respect to the production by atomic hydrogen or deuterium bombardment (less than 10%).

  4. Models for Cometary Comae Containing Negative Ions

    NASA Technical Reports Server (NTRS)

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions O(-), OH(-), C(-), CH(-) and CN(-) have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu [I]. Organic molecular anions such as C4H(-) and C6H(-) are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been fully explored. We present details of our new models for the chemistry of cometary comae that include atomic and molecular anions. We calculate the impact of these anions on the charge balance and examine their importance for cometary coma chemistry.

  5. Negative Ion Based Heating and Diagnostic Neutral Beams for ITER

    NASA Astrophysics Data System (ADS)

    Schunke, B.; Bora, D.; Antoni, V.; Bonicelli, T.; Chakraborty, A.; Cordier, J.-J.; Hemsworth, R.; Inoue, T.; Tanga, A.; Watanabe, K.

    2008-04-01

    To meet the requirements of the four operating and one start-up scenarios foreseen in the International Tokamak Experimental Reactor (ITER) a flexible heating mix will be required, which has to include a reliable contribution from neutral beams. The current baseline of ITER foresees 2 Heating Neutral Beam (HNB) systems based on negative ion technology, each operating at 1 MeV 40 A D- ions, and each capable of delivering up to 16.7 MW of D ° to the ITER plasma. A 3rd HNB injector is foreseen as an upgrade option. In addition a dedicated Diagnostic Neutral Beam (DNB) injecting 100 keV 60 A of negative hydrogen ions will be available for charge exchange resonant spectroscopy (CXRS). The significant R&D effort necessary to meet the design requirements will be provided in the Neutral Beam Test Facility (NBTF), which is to be constructed in Padua, Italy. This paper gives an overview of the current status of the neutral beam (NB) systems and the chosen configuration. The ongoing integration effort into the ITER plant is highlighted and open interface issues are identified. It is shown how installation and maintenance logistics has influenced the design. ITER operating scenarios are briefly discussed, including start-up and commissioning. For example it is now envisaged to have a low current hydrogen phase of ITER operations, essentially for commissioning of the many auxiliary systems used on ITER. The low current limits the achievable plasma density, and hence the NB energy due to shine through limitations. Therefore a possible reconfiguration of the auxiliary heating systems is now being discussed. Other NB related issues identified by the ongoing design review process are emphasized and possible impact on the implementations of the HNB and DNB systems is indicated.

  6. Negative ion source with hollow cathode discharge plasma

    DOEpatents

    Hershcovitch, Ady; Prelec, Krsto

    1983-01-01

    A negative ion source of the type where negative ions are formed by bombarding a low-work-function surface with positive ions and neutral particles from a plasma, wherein a highly ionized plasma is injected into an anode space containing the low-work-function surface. The plasma is formed by hollow cathode discharge and injected into the anode space along the magnetic field lines. Preferably, the negative ion source is of the magnetron type.

  7. Negative ion source with hollow cathode discharge plasma

    DOEpatents

    Hershcovitch, A.; Prelec, K.

    1980-12-12

    A negative ion source of the type where negative ions are formed by bombarding a low-work-function surface with positive ions and neutral particles from a plasma, wherein a highly ionized plasma is injected into an anode space containing the low-work-function surface is described. The plasma is formed by hollow cathode discharge and injected into the anode space along the magnetic field lines. Preferably, the negative ion source is of the magnetron type.

  8. The First Observation of Intra Beam Stripping of Negative Hydrogen in a Superconducting Linear Accelerator

    SciTech Connect

    Aleksandrov, Alexander V; Plum, Michael A; Shishlo, Andrei P; Galambos, John D

    2012-01-01

    We report on an experiment in which a negative hydrogen ions beam in the Spallation Neutron Source (SNS) linear accelerator was replaced with a beam of protons with similar size and dynamics. Beam loss in the superconducting part of the SNS accelerator was at least an order of magnitude lower for the proton beam. Also beam loss has a stronger dependence on intensity with H- than with proton beams. These measurements verify a recent theoretical explanation of unexpected beam losses in the SNS superconducting linear accelerator based on an intra beam stripping mechanism for negative hydrogen ions. An identification of the new physics mechanism for beam loss is important for the design of new high current linear ion accelerators and the performance improvement of existing machines

  9. Physical effects of negative air ions in a wet sauna

    NASA Astrophysics Data System (ADS)

    Watanabe, I.; Noro, Hiroshi; Ohtsuka, Yoshinori; Mano, Yukio; Agishi, Yuko

    The physical effects of negative air ions on humans were determined in an experimental sauna room equipped with an ionizer. Thirteen healthy persons took a wet sauna bath (dry bulb temperature 42° C, relative humidity 100%, 10 min exposure) with or without negative air ions. The subjects were not told when they were being exposed to negative air ions. There were no differences in the moods of these persons or changes in their blood pressures between the two saunas. The surface temperatures of the foreheads, hands, and legs in the sauna with negative ions were significantly higher than those in the sauna without ions. The pulse rates and sweat produced in the sauna with ions were singificantly higher than those in the sauna without ions. The results suggest that negative ions may amplify the effects on humans of the sauna.

  10. Installation of spectrally selective imaging system in RF negative ion source.

    PubMed

    Ikeda, K; Wünderlich, D; Fantz, U; Heinemann, B; Kisaki, M; Nagaoka, K; Nakano, H; Osakabe, M; Tsumori, K; Geng, S; Kaneko, O; Takeiri, Y

    2016-02-01

    A spectrally selective imaging system has been installed in the RF negative ion source in the International Thermonuclear Experimental Reactor-relevant negative ion beam test facility ELISE (Extraction from a Large Ion Source Experiment) to investigate distribution of hydrogen Balmer-α emission (Hα) close to the production surface of hydrogen negative ion. We selected a GigE vision camera coupled with an optical band-path filter, which can be controlled remotely using high speed network connection. A distribution of Hα emission near the bias plate has been clearly observed. The same time trend on Hα intensities measured by the imaging diagnostic and the optical emission spectroscopy is confirmed. PMID:26931995

  11. Hydrogen retention in ion irradiated steels

    SciTech Connect

    Hunn, J.D.; Lewis, M.B.; Lee, E.H.

    1998-11-01

    In the future 1--5 MW Spallation Neutron Source, target radiation damage will be accompanied by high levels of hydrogen and helium transmutation products. The authors have recently carried out investigations using simultaneous Fe/He,H multiple-ion implantations into 316 LN stainless steel between 50 and 350 C to simulate the type of radiation damage expected in spallation neutron sources. Hydrogen and helium were injected at appropriate energy and rate, while displacement damage was introduced by nuclear stopping of 3.5 MeV Fe{sup +}, 1 {micro}m below the surface. Nanoindentation measurements showed a cumulative increase in hardness as a result of hydrogen and helium injection over and above the hardness increase due to the displacement damage alone. TEM investigation indicated the presence of small bubbles of the injected gases in the irradiated area. In the current experiment, the retention of hydrogen in irradiated steel was studied in order to better understand its contribution to the observed hardening. To achieve this, the deuterium isotope ({sup 2}H) was injected in place of natural hydrogen ({sup 1}H) during the implantation. Trapped deuterium was then profiled, at room temperature, using the high cross-section nuclear resonance reaction with {sup 3}He. Results showed a surprisingly high concentration of deuterium to be retained in the irradiated steel at low temperature, especially in the presence of helium. There is indication that hydrogen retention at spallation neutron source relevant target temperatures may reach as high as 10%.

  12. Studies of transition states and radicals by negative ion photodetachment

    SciTech Connect

    Metz, R.B.

    1991-12-01

    Negative ion photodetachment is a versatile tool for the production and study of transient neutral species such as reaction intermediates and free radicals. Photodetachment of the stable XHY{sup {minus}} anion provides a direct spectroscopic probe of the transition state region of the potential energy surface for the neutral hydrogen transfer reaction X + HY {yields} XH + Y, where X and Y are halogen atoms. The technique is especially sensitive to resonances, which occur at a specific energy, but the spectra also show features due to direct scattering. We have used collinear adiabatic simulations of the photoelectron spectra to evaluate trail potential energy surfaces for the biomolecular reactions and have extended the adiabatic approach to three dimensions and used it to evaluate empirical potential energy surfaces for the I + Hl and Br + HI reactions. In addition, we have derived an empirical, collinear potential energy surface for the Br + HBr reaction that reproduces our experimental results and have extended this surface to three dimensions. Photodetachment of a negative ion can be also used to study neutral free radicals. We have studied the vibrational and electronic spectroscopy of CH{sub 2}NO{sub 2} by photoelectron spectroscopy of CH{sub 2}NO{sub 2}{sup {minus}}, determining the electron affinity of CH{sub 2}NO{sub 2}, gaining insight on the bonding of the {sup 2}B{sub 1} ground state and observing the {sup 2}A{sub 2} excited state for the first time. Negative ion photodetachment also provides a novel and versatile source of mass-selected, jet-cooled free radicals. We have studied the photodissociation of CH{sub 2}NO{sub 2} at 270, 235, and 208 nm, obtaining information on the dissociation products by measuring the kinetic energy release in the photodissociation.

  13. Study of negative ion transport phenomena in a plasma source

    NASA Astrophysics Data System (ADS)

    Riz, D.; Paméla, J.

    1996-07-01

    NIETZSCHE (Negative Ions Extraction and Transport ZSimulation Code for HydrogEn species) is a negative ion (NI) transport code developed at Cadarache. This code calculates NI trajectories using a 3D Monte-Carlo technique, taking into account the main destruction processes, as well as elastic collisions (H-/H+) and charge exchanges (H-/H0). It determines the extraction probability of a NI created at a given position. According to the simulations, we have seen that in the case of volume production, only NI produced close to the plasma grid (PG) can be extracted. Concerning the surface production, we have studied how NI produced on the PG and accelerated by the plasma sheath backward into the source could be extracted. We demonstrate that elastic collisions and charge exchanges play an important role, which in some conditions dominates the magnetic filter effect, which acts as a magnetic mirror. NI transport in various conditions will be discussed: volume/surface production, high/low plasmas density, tent filter/transverse filter.

  14. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    SciTech Connect

    Bradforth, S.E.

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound {yields} bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN{sup {minus}}, NCO{sup {minus}} and NCS{sup {minus}}. Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH{sub 3}0H,F + C{sub 2}H{sub 5}OH,F + OH and F + H{sub 2}. A time dependent framework for the simulation and interpretation of the bound {yields} free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH {yields} O({sup 3}P, {sup 1}D) + HF and F + H{sub 2}. The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H{sub 2} system, comparisons with three-dimensional quantum calculations are made.

  15. Negative ions at Titan and Enceladus: recent results.

    PubMed

    Coates, Andrew J; Wellbrock, Anne; Lewis, Gethyn R; Jones, Geraint H; Young, David T; Crary, Frank J; Waite, J Hunter; Johnson, Robert E; Hille, Thomas W; Sittler, Edward C

    2010-01-01

    The detection of heavy negative ions (up to 13 800 amu) in Titan's ionosphere is one of the tantalizing new results from the Cassini mission. These heavy ions indicate for the first time the existence of heavy hydrocarbon and nitrile molecules in this primitive Earth-like atmosphere. These ions were suggested to be precursors of aerosols in Titan's atmosphere and may precipitate to the surface as tholins. We present the evidence for and the analysis of these heavy negative ions at Titan. In addition we examine the variation of the maximum mass of the Titan negative ions with altitude and latitude for the relevant encounters so far, and we discuss the implications for the negative ion formation process. We present data from a recent set of encounters where the latitude was varied between encounters, with other parameters fixed. Models are beginning to explain the low mass negative ions, but the formation process for the higher mass ions is still not understood. It is possible that the structures may be chains, rings or even fullerenes. Negative ions, mainly water clusters in this case, were seen during Cassini's recent close flybys of Enceladus. We present mass spectra from the Enceladus plume, showing water clusters and additional species. As at Titan, the negative ions indicate chemical complexities which were unknown before the Cassini encounters, and are indicative of a complex balance between neutrals and positively and negatively charged ions. PMID:21302552

  16. Effect of fast positive ions incident on caesiated plasma grid of negative ion source

    SciTech Connect

    Bacal, M.

    2012-02-15

    This paper describes the effect on negative ion formation on a caesiated surface of the backscattering of positive ions approaching it with energy of a few tens of eV. For a positive ion energy of 45 eV, the surface produced negative ion current density due to these fast positive ions is 12 times larger than that due to thermal atoms, thus dominating the negative ion surface production instead of the thermal atoms, as considered until now.

  17. Threshold photodetachment spectroscopy of negative ions

    SciTech Connect

    Kitsopoulos, T.N.

    1991-12-01

    This thesis is concerned with the development and application of high resolution threshold photodetachment spectroscopy of negative ions. Chapter I deals with the principles of our photodetachment technique, and in chapter II a detailed description of the apparatus is presented. The threshold photodetachment spectra of I{sup {minus}}, and SH{sup {minus}}, presented in the last sections of chapter II, indicated that a resolution of 3 cm{sup {minus}1} can be achieved using our technique. In chapter III the threshold photodetachment spectroscopy study of the transition state region of I + HI and I + Di reactions is discussed. Our technique probes the transition state region directly, and the results of our study are the first unambiguous observations of reactive resonances in a chemical reaction. Chapters IV, V and VI are concerned with the spectroscopy of small silicon and carbon clusters. From our spectra we were able to assign electronic state energies and vibrational frequencies for the low lying electronics states of Si{sub n} (n=2,3,4), C{sub 5} and their corresponding anions.

  18. Anisotropic negative-ion emission from cluster nanoplasmas

    NASA Astrophysics Data System (ADS)

    Rajeev, R.; Dalui, Malay; Trivikram, T. Madhu; Rishad, K. P. M.; Krishnamurthy, M.

    2015-06-01

    Recent experiments have shown that the enhanced charge transfer by Rydberg excited clusters (ECTREC) reduces the highly charged ions very efficiently to neutral atoms and negative ions with little loss of momentum. Neutral-atom emission is anisotropic with respect to the laser polarization and the anisotropy is larger than that of the ion emission from Coulomb explosion of isolated single clusters. In such a scenario, it is expected that the negative-ion emission (like neutrals) should be anisotropic and have larger propensity along the laser polarization than in the perpendicular direction. Further, it may be anticipated that negative-ion emission is more anisotropic than neutral-atom emission if ECTREC is taken in to account. We demonstrate that the negative-ion emission is anisotropic. Contrary to expectations, the negative-ion emission anisotropy is not more than that of the neutral-atom emission. We show that this can be rationalized if low-energy (about 10 eV) electron collisional detachment of the negative ions is taken into account. Electron collisional detachment depletes the negative-ion yield preferentially along the laser polarization direction and reduces the negative-ion emission anisotropy.

  19. Negative ion gas-phase chemistry of arenes.

    PubMed

    Danikiewicz, Witold; Zimnicka, Magdalena

    2016-01-01

    Reactions of aromatic and heteroaromatic compounds involving anions are of great importance in organic synthesis. Some of these reactions have been studied in the gas phase and are occasionally mentioned in reviews devoted to gas-phase negative ion chemistry, but no reviews exist that collect all existing information about these reactions. This work is intended to fill this gap. In the first part of this review, methods for generating arene anions in the gas phase and studying their physicochemical properties and fragmentation reactions are presented. The main topics in this part are as follows: processes in which gas-phase arene anions are formed, measurements and calculations of the proton affinities of arene anions, proton exchange reactions, and fragmentation processes of substituted arene anions, especially phenide ions. The second part is devoted to gas-phase reactions of arene anions. The most important of these are reactions with electrophiles such as carbonyl compounds and α,β-unsaturated carbonyl and related compounds (Michael acceptors). Other reactions including oxidation of arene anions and halogenophilic reactions are also presented. In the last part of the review, reactions of electrophilic arenes with nucleophiles are discussed. The best known of these is the aromatic nucleophilic substitution (SN Ar) reaction; however, other processes that lead to the substitution of a hydrogen atom in the aromatic ring are also very important. Aromatic substrates in these reactions are usually but not always nitroarenes bearing other substituents in the ring. The first step in these reactions is the formation of an anionic σ-adduct, which, depending on the substituents in the aromatic ring and the structure of the attacking nucleophile, is either an intermediate or a transition state in the reaction path. In the present review, we attempted to collect the results of both experimental and computational studies of the aforementioned reactions conducted since the

  20. Observation of the negative ions: Ra[sup [minus

    SciTech Connect

    Zhao, X.; Nadeau, M.; Garwan, M.A.; Kilius, L.R.; Litherland, A.E. )

    1993-11-01

    The negative ions of the isotopes [sup 226]Ra, [sup 231]Pa, and [sup 244]Pu have been observed by means of accelerator mass spectrometry and their properties compared with the negative ions of Th and U. The electron affinities of all these elements have been estimated to be similar and greater than 50 meV.

  1. Spectroscopy of transient neutral species via negative ion photoelectron spectroscopy

    SciTech Connect

    Weaver, A.

    1991-12-01

    Negative ion photoelectron spectroscopy has been used to study two types of transient neutral species: bound free radicals (NO{sub 2} and NO{sub 3}) and unstable neutral species ([IHI] and [FH{sub 2}]). The negative ion time-of-flight photoelectron spectrometer used for these experiments is described in detail.

  2. Spectroscopy of transient neutral species via negative ion photoelectron spectroscopy

    SciTech Connect

    Weaver, A.

    1991-12-01

    Negative ion photoelectron spectroscopy has been used to study two types of transient neutral species: bound free radicals (NO{sub 2} and NO{sub 3}) and unstable neutral species ((IHI) and (FH{sub 2})). The negative ion time-of-flight photoelectron spectrometer used for these experiments is described in detail.

  3. Electron energy recovery system for negative ion sources

    DOEpatents

    Dagenhart, W.K.; Stirling, W.L.

    1979-10-25

    An electron energy recovery system for negative ion sources is provided. The system, employing crossed electric and magnetic fields, separates the electrons from the ions as they are extracted from the ion source plasma generator and before the ions are accelerated to their full energy. With the electric and magnetic fields oriented 90/sup 0/ to each other, the electrons remain at approximately the electrical potential at which they were generated. The electromagnetic forces cause the ions to be accelerated to the full accelerating supply voltage energy while being deflected through an angle of less than 90/sup 0/. The electrons precess out of the accelerating field region into an electron recovery region where they are collected at a small fraction of the full accelerating supply energy. It is possible, by this method, to collect > 90% of the electrons extracted along with the negative ions from a negative ion source beam at < 4% of full energy.

  4. A fluorescence enhancement-based sensor for hydrogen sulfate ion.

    PubMed

    Yang, Shih-Tse; Liao, De-Jhong; Chen, Shau-Jiun; Hu, Ching-Han; Wu, An-Tai

    2012-04-01

    Sugar-aza-crown ether-based cavitand 1 can act as a selective turn-on fluorescence sensor for hydrogen sulfate ion in methanol among a series of tested anions. Spectroscopic studies, particularly NMR spectroscopy, revealed that the C-H hydrogen bonding between 1,2,3-triazole ring of cavitand 1 and hydrogen sulfate ion is crucial for the high selectivity of the receptor for hydrogen sulfate.

  5. Time evolution of negative ion profile in a large cesiated negative ion source applicable to fusion reactors.

    PubMed

    Yoshida, M; Hanada, M; Kojima, A; Kashiwagi, M; Umeda, N; Hiratsuka, J; Ichikawa, M; Watanabe, K; R Grisham, L; Tsumori, K; Kisaki, M

    2016-02-01

    To understand the physics of the cesium (Cs) recycling in the large Cs-seeded negative ion sources relevant to ITER and JT-60SA with ion extraction area of 45-60 cm × 110-120 cm, the time evolution of the negative ion profile was precisely measured in JT-60SA where the ion extraction area is longitudinally segmented into 5. The Cs was seeded from the oven at 180 °C to the ion source. After 1 g of Cs input, surface production of the negative ions appeared only in the central segment where a Cs nozzle was located. Up to 2 g of Cs, the negative ion profile was longitudinally expanded over full ion extraction area. The measured time evolution of the negative ion profile has the similar tendency of distribution of the Cs atoms that is calculated. From the results, it is suggested that Cs atom distribution is correlated with the formation of the negative ion profile. PMID:26932026

  6. Ion beam studies of hydrogen in metals

    SciTech Connect

    Myers, S.M.; Wampler, W.R.; Besenbacher, F.; Robinson, S.L.; Moody, N.R.

    1984-01-01

    Methods based on ion implantation and nuclear reaction analysis were used to investigate the behavior of hydrogen isotopes in metals. The binding enthalpy of deuterium (D) at irradiation effects, He bubbles, D/sub 2/ bubbles, and metal-oxide interfaces was measured for Al, Fe, Ni, Cu, Pd, austenitic stainless steel, Inconel, and amorphous Fe/sub 40/Ni/sub 40/P/sub 14/B/sub 6/. The binding enthalpies determined for the pure metals are in excellent agreement with mechanistic calculations based on effective-medium theory and other information. Surface-limited release of D from Fe, stainless steel, and Inconel was measured as a function of temperature and the state of surface oxidation. The release rate was accurately proportional to the square of the D concentration in solution, permitting the results to be expressed in terms of a surface recombination coefficient. This quantity was up to four orders of magnitude greater for an ion-sputtered surface than for a surface with electropolish oxide. The diffusion coefficient and solid solubility of tritium in stainless steel were measured for the first time at the ice point, thereby extending downward by three orders of magnitude the diffusivities available from conventional permeation experiments. Deuterium concentration profiles resulting from electrochemical charging of Incoloy 903 were measured as a function of charging current, thereby providing a direct, systematic calibration of such charging in an austenitic material where conventional permeation measurements are precluded by the small hydrogen diffusion rate.

  7. Development of negative ion source at the IPP Nagoya University

    SciTech Connect

    Kuroda, T; Okamura, H; Kaneko, O; Oka, Y

    1980-01-01

    Preliminary experiments have been made to develop a high current H/sup -/ ion surface for a neutral beam injector. Initially, an H/sup -/ ion source of the magnetron type has been investigated in order to determine its physical and technical problems. A second plasma source for negative ion production is under construction, which is based on controlled plasma production. This paper describes preliminary experimental results of the magnetron ion source and some features in the new type of plasma source.

  8. Negative Ions Enhance Survival of Membrane Protein Complexes

    NASA Astrophysics Data System (ADS)

    Liko, Idlir; Hopper, Jonathan T. S.; Allison, Timothy M.; Benesch, Justin L. P.; Robinson, Carol V.

    2016-06-01

    Membrane protein complexes are commonly introduced to the mass spectrometer solubilized in detergent micelles. The collisional activation used to remove the detergent, however, often causes protein unfolding and dissociation. As in the case for soluble proteins, electrospray in the positive ion mode is most commonly used for the study of membrane proteins. Here we show several distinct advantages of employing the negative ion mode. Negative polarity can yield lower average charge states for membrane proteins solubilized in saccharide detergents, with enhanced peak resolution and reduced adduct formation. Most importantly, we demonstrate that negative ion mode electrospray ionization (ESI) minimizes subunit dissociation in the gas phase, allowing access to biologically relevant oligomeric states. Together, these properties mean that intact membrane protein ions can be generated in a greater range of solubilizing detergents. The formation of negative ions, therefore, greatly expands the possibilities of using mass spectrometry on this intractable class of protein.

  9. Negative ion-driven associated particle neutron generator

    DOE PAGESBeta

    Antolak, A. J.; Leung, K. N.; Morse, D. H.; Donovan, D. C.; Chames, J. M.; Whaley, J. A.; Buchenauer, D. A.; Chen, A. X.; Hausladen, P. A.; Liang, F.

    2015-10-09

    We describe an associated particle neutron generator that employs a negative ion source to produce high neutron flux from a small source size. Furthermore, negative ions produced in an rf-driven plasma source are extracted through a small aperture to form a beam which bombards a positively biased, high voltage target electrode. Electrons co-extracted with the negative ions are removed by a permanent magnet electron filter. The use of negative ions enables high neutron output (100% atomic ion beam), high quality imaging (small neutron source size), and reliable operation (no high voltage breakdowns). Finally, the neutron generator can operate in eithermore » pulsed or continuous-wave (cw) mode and has been demonstrated to produce 106 D-D n/s (equivalent to similar to 108 D-T n/s) from a 1 mm-diameter neutron source size to facilitate high fidelity associated particle imaging.« less

  10. Negative ion-driven associated particle neutron generator

    SciTech Connect

    Antolak, A. J.; Leung, K. N.; Morse, D. H.; Donovan, D. C.; Chames, J. M.; Whaley, J. A.; Buchenauer, D. A.; Chen, A. X.; Hausladen, P. A.; Liang, F.

    2015-10-09

    We describe an associated particle neutron generator that employs a negative ion source to produce high neutron flux from a small source size. Furthermore, negative ions produced in an rf-driven plasma source are extracted through a small aperture to form a beam which bombards a positively biased, high voltage target electrode. Electrons co-extracted with the negative ions are removed by a permanent magnet electron filter. The use of negative ions enables high neutron output (100% atomic ion beam), high quality imaging (small neutron source size), and reliable operation (no high voltage breakdowns). Finally, the neutron generator can operate in either pulsed or continuous-wave (cw) mode and has been demonstrated to produce 106 D-D n/s (equivalent to similar to 108 D-T n/s) from a 1 mm-diameter neutron source size to facilitate high fidelity associated particle imaging.

  11. A negative ion source test facility.

    PubMed

    Melanson, S; Dehnel, M; Potkins, D; Theroux, J; Hollinger, C; Martin, J; Philpott, C; Stewart, T; Jackle, P; Williams, P; Brown, S; Jones, T; Coad, B; Withington, S

    2016-02-01

    Progress is being made in the development of an Ion Source Test Facility (ISTF) by D-Pace Inc. in collaboration with Buckley Systems Ltd. in Auckland, NZ. The first phase of the ISTF is to be commissioned in October 2015 with the second phase being commissioned in March 2016. The facility will primarily be used for the development and the commercialization of ion sources. It will also be used to characterize and further develop various D-Pace Inc. beam diagnostic devices. PMID:26931991

  12. The development of the radio frequency driven negative ion source for neutral beam injectors (invited)

    SciTech Connect

    Kraus, W.; Fantz, U.; Franzen, P.; Froeschle, M.; Heinemann, B.; Riedl, R.; Wuenderlich, D.

    2012-02-15

    Large and powerful negative hydrogen ion sources are required for the neutral beam injection (NBI) systems of future fusion devices. Simplicity and maintenance-free operation favors RF sources, which are developed intensively at the Max-Planck-Institut fuer Plasmaphysik (IPP) since many years. The negative hydrogen ions are generated by caesium-enhanced surface conversion of atoms and positive ions on the plasma grid surface. With a small scale prototype the required high ion current density and the low fraction of co-extracted electrons at low pressure as well as stable pulses up to 1 h could be demonstrated. The modular design allows extension to large source dimensions. This has led to the decision to choose RF sources for the NBI of the international fusion reactor, ITER. As an intermediate step towards the full size ITER source at IPP, the development will be continued with a half-size source on the new ELISE testbed. This will enable to gain experience for the first time with negative hydrogen ion beams from RF sources of these dimensions.

  13. Evolution of an expanding dusty plasma with negative ions

    SciTech Connect

    Kechouri, B.; Djebli, M.

    2006-11-15

    The dusty plasma radial expansion is studied in the case of a spherical as well as cylindrical configuration. The effect of negative ions is introduced through the dust charge fluctuation equation. Electrons, positive, and negative ions are modelled by the Boltzmann distribution function and the dust grains by fluid equations. Using the self-similar theory, the nonlinear set of differential equations is solved numerically. It is found that the dust charge presents a critical value which depends on the negative ion species type. It is also found that the dust expansion ends earlier and the lighter particle densities profiles depend on the dust initial charge.

  14. Numerical simulations of the first operational conditions of the negative ion test facility SPIDER

    NASA Astrophysics Data System (ADS)

    Serianni, G.; Agostinetti, P.; Antoni, V.; Baltador, C.; Cavenago, M.; Chitarin, G.; Marconato, N.; Pasqualotto, R.; Sartori, E.; Toigo, V.; Veltri, P.

    2016-02-01

    In view of the realization of the negative ion beam injectors for ITER, a test facility, named SPIDER, is under construction in Padova (Italy) to study and optimize production and extraction of negative ions. The present paper is devoted to the analysis of the expected first operations of SPIDER in terms of single-beamlet and multiple-beamlet simulations of the hydrogen beam optics in various operational conditions. The effectiveness of the methods adopted to compensate for the magnetic deflection of the particles is also assessed. Indications for a sequence of the experimental activities are obtained.

  15. Numerical simulations of the first operational conditions of the negative ion test facility SPIDER.

    PubMed

    Serianni, G; Agostinetti, P; Antoni, V; Baltador, C; Cavenago, M; Chitarin, G; Marconato, N; Pasqualotto, R; Sartori, E; Toigo, V; Veltri, P

    2016-02-01

    In view of the realization of the negative ion beam injectors for ITER, a test facility, named SPIDER, is under construction in Padova (Italy) to study and optimize production and extraction of negative ions. The present paper is devoted to the analysis of the expected first operations of SPIDER in terms of single-beamlet and multiple-beamlet simulations of the hydrogen beam optics in various operational conditions. The effectiveness of the methods adopted to compensate for the magnetic deflection of the particles is also assessed. Indications for a sequence of the experimental activities are obtained. PMID:26932099

  16. Excitation of lower hybrid waves by a gyrating ion beam in a negative ion plasma

    SciTech Connect

    Sharma, Jyotsna; Jain, V. K.; Sharma, Suresh C.; Gahlot, Ajay

    2013-03-15

    A gyrating ion beam propagating through a magnetized plasma cylinder containing K{sup +} positive ions, electrons, and SF{sub 6}{sup -} negative ions drives electrostatic lower hybrid waves to instability via Cyclotron interaction. Numerical calculations of the unstable mode frequencies and growth rates of both the unstable positive ion and negative ion modes have been carried out for the existing negative ion plasma parameters. It is found that the unstable mode frequencies of both the modes increase, with the relative density of negative ions. In addition, the growth rates of both the unstable modes also increases with relative density of negative ions. Moreover, the growth rates of both the unstable modes scale as the one-third power of the beam density. The frequencies of both the unstable modes also increase with the magnetic fields. The real part of the unstable wave frequency increases as almost the square root of the beam energy.

  17. Formation and photodetachment of cold metal cluster negative ions

    NASA Astrophysics Data System (ADS)

    Zheng, L.-S.; Brucat, P. J.; Pettiette, C. L.; Yang, S.; Smalley, R. E.

    1985-10-01

    A general method is described for the formation of cold metal cluser negative ion beams which serve as excellent sources for photodetachment experiments. The method involves the pulsed laser vaporization of a metal target at the throat of a pulsed supersonic helium expansion. By the optimization of source conditions, intense beams (greater than 105 ions/pulse) of both positive and negative ions are produced routinely. Ionization of the metal cluster molecules, either during vaporization or by irradiation with 193 nm light, occurs prior to supersonic expansion and produces a cold plasma entrained in the neural flow that is renitent to stray electric and magnetic fields, unlike photoions produced in the collisionless downstream molecular beam. The enhancement of the negative ion flux by 193 nm irradiation is believed to be evidence for efficient electron attachment of low energy photoelectrons generated in the nozzle region. This attachment process, however, is apparently not effective for molecules containing less than ˜4 metal atoms. Laser irradition of mass-selected cluster anions extracted from these cold ion beams reveal that photodetachment of the metal cluster negative ion is always the preferred pathway, even when fragmentation of the ion is possible. This new negative ion production technique should therefore permit measurement of both electron affinities and photoelectron spectra as a function of cluster size and composition.

  18. Energization of ionospheric ions by electrostatic hydrogen cyclotron waves

    NASA Technical Reports Server (NTRS)

    Singh, N.; Schunk, R. W.; Sojka, J. J.

    1981-01-01

    Interactions between ionospheric ions and electrostatic hydrogen cyclotron waves are studied numerically in an investigation of a possible mechanism for the energization of the low-energy ionospheric ions flowing along geomagnetic field lines to high altitudes. Ion equations of motion are solved numerically for a given number of O(+), He(+) and He(2+) ions initially in a Maxwellian distribution. All the ions considered are found capable of undergoing stochastic acceleration by a coherent electrostatic hydrogen cyclotron wave with parameters typical of the auroral plasma above 1 earth radius. The fraction of the initial ion population undergoing heating depends strongly on the mass, charge and initial temperature of the ion species, with O(+) ions only heated when their initial temperature is approximately greater than the hydrogen temperature and the lighter ions able to be heated even when cold, due to cyclotron resonant stochastic heating.

  19. Cesium vapor thermionic converter anomalies arising from negative ion emission

    NASA Astrophysics Data System (ADS)

    Rasor, Ned S.

    2016-08-01

    Compelling experimental evidence is given that a longstanding limit encountered on cesium vapor thermionic energy converter performance improvement and other anomalies arise from thermionic emission of cesium negative ions. It is shown that the energy that characterizes thermionic emission of cesium negative ions is 1.38 eV and, understandably, is not the electron affinity 0.47 eV determined for the photodetachment threshold of the cesium negative ion. The experimental evidence includes measurements of collector work functions and volt-ampere characteristics in quasi-vacuum cesium vapor thermionic diodes, along with reinterpretation of the classic Taylor-Langmuir S-curve data on electron emission in cesium vapor. The quantitative effects of negative ion emission on performance in the ignited, unignited, and quasi-vacuum modes of cesium vapor thermionic converter operation are estimated.

  20. New versions of sources for nuclear polarized negative ion production

    SciTech Connect

    Dudnikov, V.G.; Shabalin, A.L. ); Wojtsekhowski, B.B. ); Belov, A.S.; Kuzik, V.E.; Plohinsky, Y.V.; Yakushev, V.P. )

    1992-10-05

    Several variants of sources for nuclear polarized negative ion production have been proposed and tested. The simple adaptation of a high intensity polarized proton source for nuclear polarized H[sup [minus

  1. High brilliance negative ion and neutral beam source

    DOEpatents

    Compton, Robert N.

    1991-01-01

    A high brilliance mass selected (Z-selected) negative ion and neutral beam source having good energy resolution. The source is based upon laser resonance ionization of atoms or molecules in a small gaseous medium followed by charge exchange through an alkali oven. The source is capable of producing microampere beams of an extremely wide variety of negative ions, and milliampere beams when operated in the pulsed mode.

  2. Field-Reversal Source for Negative Halogen Ions

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Orient, O. J.; Aladzhadzhyan, S. H.

    1987-01-01

    Large zero-energy electron-attachment cross sections result in intense ion beams. Concept for producing negative halogen ions takes advantage of large cross sections at zero kinetic energy for dissociative attachment of electrons to such halogen-containing gases as SF6, CFCI3, and CCI4.

  3. Negative thermal ion mass spectrometry of osmium, rhenium, and iridium

    NASA Technical Reports Server (NTRS)

    Creaser, R. A.; Papanastassiou, D. A.; Wasserburg, G. J.

    1991-01-01

    This paper describes a technique for obtaining, in a conventional surface ionization mass spectrometer, intense ion beams of negatively charged oxides of Os, Re, and Ir by thermal ionization. It is shown that the principal ion species of these ions are OsO3(-), ReO4(-), and IrO2(-), respectively. For Re-187/Os-187 studies, this technique offers the advantage of isotopic analyses without prior chemical separation of Re from Os.

  4. Production of negative osmium ions by laser desorption and ionization.

    PubMed

    Rodríguez, D; Sonnenschein, V; Blaum, K; Block, M; Kluge, H-J; Lallena, A M; Raeder, S; Wendt, K

    2010-01-01

    The interest to produce negative osmium ions is manifold in the realm of high-accuracy ion trap experiments: high-resolution nearly Doppler-free laser spectroscopy, antihydrogen formation in its ground state, and contributions to neutrino mass spectrometry. Production of these ions is generally accomplished by sputtering an Os sample with Cs(+) ions at tens of keV. Though this is a well-established method commonly used at accelerators, these kind of sources are quite demanding and tricky to operate. Therefore, the development of a more straightforward and cost effective production scheme will be of benefit for ion trap and other experiments. Such a scheme makes use of desorption and ionization with pulsed lasers and identification of the ions by time-of-flight mass spectrometry. First investigations of negative osmium ion production using a pulsed laser for desorption and ionization and a commercial matrix-assisted laser desorption/ionization time-of-flight system for identification has demonstrated the suitability of this technique. More than 10(3) negative osmium ions per shot were registered after bombarding pure osmium powder with a 5 ns pulse width Nd:yttrium aluminum garnet laser. The limitation in the ion number was imposed by the detection limit of the microchannel plate detector.

  5. Study of the negative ion extraction mechanism from a double-ion plasma in negative ion sources

    SciTech Connect

    Goto, I.; Nishioka, S.; Hatayama, A.; Miyamoto, K.

    2015-04-08

    We have developed a 2D3V-PIC model of the extraction region, aiming to clarify the basic extraction mechanism of H{sup −} ions from the double-ion plasma in H{sup −} negative ion sources. The result shows the same tendency of the H{sup −} ion density n{sub H{sup −}} as that observed in the experiments, i.e.,n{sub H{sup −}} in the upstream region away from the plasma meniscus (H{sup −} emitting surface) has been reduced by applying the extraction voltage. At the same time, relatively slow temporal oscillation of the electric potential compared with the electron plasma frequency has been observed in the extraction region. Results of the systematic study using a 1D3V-PIC model with the uniform magnetic field confirm the result that the electrostatic oscillation is identified to be lower hybrid wave. The effect of this oscillation on the H{sup −} transport will be studied in the future.

  6. Motivation of concepts for the negative ion extraction from a single element of the matrix source.

    PubMed

    Lishev, St; Shivarova, A; Yordanov, D

    2016-02-01

    A single element of a matrix source of negative hydrogen ions (a planar-coil inductively driven small-radius discharge equipped with an extraction system) is studied regarding the ion extraction. Since the spatial distribution of the negative ions obeys that of the dc potential, the latter is controlled by applying a high bias to the plasma electrode of the extraction system. This leads to discharge maintenance by both rf and dc power deposition and, respectively, to similarities with the axial profile of the dc potential in the glow discharges. The discharge length, the applied rf power, and the bias to the plasma electrode and its radius are the parameters varied in determination of proper conditions for the ion extraction. PMID:26931997

  7. Negative Dielectric Constant Material Based on Ion Conducting Materials

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2014-01-01

    Metamaterials or artificial negative index materials (NIMs) have generated great attention due to their unique and exotic electromagnetic properties. One exemplary negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly(benzimidazole) (PBI). The doped PBI showed a negative dielectric constant at megahertz (MHz) frequencies due to its reduced plasma frequency and an induction effect. The magnitude of the negative dielectric constant and the resonance frequency were tunable by doping concentration. The highly doped PBI showed larger absolute magnitude of negative dielectric constant at just above its resonance frequency than the less doped PBI.

  8. Modeling of negative ion transport in a plasma source

    NASA Astrophysics Data System (ADS)

    Riz, David; Paméla, Jérôme

    1998-08-01

    A code called NIETZSCHE has been developed to simulate the negative ion transport in a plasma source, from their birth place to the extraction holes. The ion trajectory is calculated by numerically solving the 3-D motion equation, while the atomic processes of destruction, of elastic collision H-/H+ and of charge exchange H-/H0 are handled at each time step by a Monte-Carlo procedure. This code can be used to calculate the extraction probability of a negative ion produced at any location inside the source. Calculations performed with NIETZSCHE have allowed to explain, either quantitatively or qualitatively, several phenomena observed in negative ion sources, such as the isotopic H-/D- effect, and the influence of the plasma grid bias or of the magnetic filter on the negative ion extraction. The code has also shown that in the type of sources contemplated for ITER, which operate at large arc power densities (>1 W cm-3), negative ions can reach the extraction region provided if they are produced at a distance lower than 2 cm from the plasma grid in the case of «volume production» (dissociative attachment processes), or if they are produced at the plasma grid surface, in the vicinity of the extraction holes.

  9. Signal Propagation in Collisional Plasma with Negative Ions

    SciTech Connect

    I. Kaganovich; S.V. Berezhnoi; C.B. Shin

    2000-12-18

    The transport of charged species in collisional currentless plasmas is traditionally thought of as a diffusion-like process. In this paper, it is demonstrated that, in contrast to two-component plasma, containing electrons and positive ions, the transport of additional ions in multi-species plasmas is not governed by diffusion, rather described by nonlinear convection. As a particular example, plasmas with the presence of negative ions have been studied. The velocity of a small perturbation of negative ions was found analytically and validated by numerical simulation. As a result of nonlinear convection, initially smooth ion density profiles break and form strongly inhomogeneous shock-like fronts. These fronts are different from collisionless shocks and shocks in fully ionized plasma. The structure of the fronts has been found analytically and numerically.

  10. Maximizing ion current by space-charge neutralization using negative ions and dust particles

    SciTech Connect

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

    2005-05-15

    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.

  11. Molecular and negative ion production by a standard electron cyclotron resonance ion source

    SciTech Connect

    Racz, R.; Biri, S.; Juhasz, Z.; Sulik, B.

    2012-02-15

    Molecular and negative ion beams, usually produced in special ion sources, play an increasingly important role in fundamental and applied atomic physics. The ATOMKI-ECRIS is a standard ECR ion source, designed to provide highly charged ion (HCI) plasmas and beams. In the present work, H{sup -}, O{sup -}, OH{sup -}, O{sub 2}{sup -}, C{sup -}, C{sub 60}{sup -} negative ions and H{sub 2}{sup +}, H{sub 3}{sup +}, OH{sup +}, H{sub 2}O{sup +}, H{sub 3}O{sup +}, O{sub 2}{sup +} positive molecular ions were generated in this HCI-ECRIS. Without any major modification in the source and without any commonly applied tricks (such as usage of cesium or magnetic filter), negative ion beams of several {mu}A and positive molecular ion beams in the mA range were successfully obtained.

  12. Effect of microsolvation on hydrogen trapping potential of metal ions

    NASA Astrophysics Data System (ADS)

    Das, Ranjita; Bandaru, Sateesh; D'mello, Viola Caroline; Chattaraj, Pratim Kumar

    2013-03-01

    A thorough analysis is carried out to understand how the microsolvation affects the hydrogen adsorbing capacity of metal ions in the presence as well as absence of the counter ions. Calculations are done at different levels of theory by using different functionals and basis sets and also by using the BSSE correction. The Be2+ ion doped systems exhibit stronger interaction with the hydrogen molecule than the other metal doped systems. The extent of interaction is less affected by the method of computation. The reaction free energy values imply that adsorption on alkaline earth metal doped systems is spontaneous at room temperature. Interaction energies are favorable for hydrogen adsorption on the systems containing alkaline earth metal ions and the gravimetric density of adsorbed hydrogen molecule is more in those containing the alkali metal ions.

  13. Effect of Coulomb collision on the negative ion extraction mechanism in negative ion sources.

    PubMed

    Goto, I; Miyamoto, K; Nishioka, S; Mattei, S; Lettry, J; Abe, S; Hatayama, A

    2016-02-01

    To improve the H(-) ion beam optics, it is necessary to understand the energy relaxation process of surface produced H(-) ions in the extraction region of Cs seeded H(-) ion sources. Coulomb collisions of charged particles have been introduced to the 2D3V-PIC (two dimension in real space and three dimension in velocity space particle-in-cell) model for the H(-) extraction by using the binary collision model. Due to Coulomb collision, the lower energy part of the ion energy distribution function of H(-) ions has been greatly increased. The mean kinetic energy of the surface produced H(-) ions has been reduced to 0.65 eV from 1.5 eV. It has been suggested that the beam optics of the extracted H(-) ion beam is strongly affected by the energy relaxation process due to Coulomb collision. PMID:26932090

  14. Issues in the understanding of negative ion extraction for fusion

    NASA Astrophysics Data System (ADS)

    Boeuf, J. P.; Fubiani, G.; Garrigues, L.

    2016-08-01

    A number of recent papers have been devoted to the modeling of negative ion extraction using particle simulations but the published results are not entirely satisfactory and not fully consistent with experiments. Issues raised by the simulations concern the saturation of the negative ion current emitted from the caesiated plasma grid surface, its distribution along the surface, the shape of the meniscus formed around each grid aperture, the distribution and depth of the potential in the virtual cathode, and the profile of the extracted beamlet. These are important issues since they have direct impact on the properties of the extracted negative ion beam (intensity, brightness, aberration). In this paper we first summarize recently published model results that are unexpected and counter-intuitive since they predict that negative ions are extracted from regions of the grid that are directly exposed to the large extraction voltage (i.e. as in vacuum and without the need for a neutralizing background plasma). We then illustrate, with results from two-dimensional particle-in-cell Monte Carlo collision simulations, some regimes of negative ion extraction that are more consistent with the expected physics.

  15. Modeling of negative ion transport in a plasma source (invited)

    NASA Astrophysics Data System (ADS)

    Riz, David; Paméla, Jérôme

    1998-02-01

    A code called NIETZSCHE has been developed to simulate the negative ion transport in a plasma source, from their birth place to the extraction holes. The H-/D- trajectory is calculated by numerically solving the 3D motion equation, while the atomic processes of destruction, of elastic collision with H+/D+ and of charge exchange with H0/D0 are handled at each time step by a Monte Carlo procedure. This code can be used to calculate the extraction probability of a negative ion produced at any location inside the source. Calculations performed with NIETZSCHE have been allowed to explain, either quantitatively or qualitatively, several phenomena observed in negative ion sources, such as the isotopic H-/D- effect, and the influence of the plasma grid bias or of the magnetic filter on the negative ion extraction. The code has also shown that, in the type of sources contemplated for ITER, which operate at large arc power densities (>1 W cm-3), negative ions can reach the extraction region provided they are produced at a distance lower than 2 cm from the plasma grid in the case of volume production (dissociative attachment processes), or if they are produced at the plasma grid surface, in the vicinity of the extraction holes.

  16. Characteristics of ion acoustic solitary waves in a negative ion plasma with superthermal electrons

    SciTech Connect

    Rouhani, M. R.; Ebne Abbasi, Z.

    2012-11-15

    The behavior of ion acoustic solitons in a plasma including positive and negative ions and kappa distributed electrons is studied, using both small amplitude and arbitrary amplitude approaches. The existence regions of compressive and rarefactive solitons will depend on negative to positive ion density ratio ({nu}) and kappa parameter as well as positive to negative ion mass ratio (Q). The numerical analysis of Sagdeev potential shows that for a chosen plasma with fixed Q, the existence regime of compressive solitons is decreased (increased) by increasing density ratio (kappa parameter), while for rarefactive solitons these conditions are quite opposite. Additionally, the possibility of propagation of both compressive and rarefactive subsonic solitons is investigated. It is found that by increasing negative ions, the existence domains of subsonic solitons are decreased, so that in excess of negative ions subsonic solitons will not propagate even at the presence of superthermal electrons. Indeed, there is a critical negative ion density ratio for all values of kappa, above that only supersonic solitons are observed. Furthermore, in addition to the previous results based on Cairns-distributed electrons [R. A. Cairns et al., Geophys. Res. Lett. 22, 2709 (1995)], which predicted that both compressive and rarefactive solitons can coexist simultaneously, we have also found the regions of {nu} and {kappa} in which either positive or negative potentials are permitted (i.e., not together). This research will be helpful in understanding the properties of space and laboratory plasmas containing negative ions with energetic electrons.

  17. Hydrogen doppler spectroscopy using 15N ions

    NASA Astrophysics Data System (ADS)

    Borucki, L.; Becker, H. W.; Gorris, F.; Kubsky, S.; Schulte, W. H.; Rolfs, C.

    The energy spread of atomic and molecular ion beams from the 4 MV Dynamitron tandem accelerator at the Ruhr-Universität Bochum has been studied and in part minimized. Using the ER= 6.40 MeV narrow resonance in 1H(15N,αγ)12C with an 15N energy spread of 4.55 keV, the Doppler broadening for several hydrogen-bearing gases was found to be in good agreement with expectation: e.g. for NH3 gas a rotational-vibrational Doppler width of 10.41 +/- 0.25 keV was observed (theory = 10.4 keV). Studies of the vibrational Doppler widths of H-bonds on a Si <100> surface were performed using a 4πγ-ray detection system together with UHV-chambers for sample preparation, transport, and analysis. The results showed that further improvements in the experimental set-ups are needed for such investigations.

  18. Electron energy recovery system for negative ion sources

    DOEpatents

    Dagenhart, William K.; Stirling, William L.

    1982-01-01

    An electron energy recovery system for negative ion sources is provided. The system, employs crossed electric and magnetic fields to separate the electrons from ions as they are extracted from a negative ion source plasma generator and before the ions are accelerated to their full kinetic energy. With the electric and magnetic fields oriented 90.degree. to each other, the electrons are separated from the plasma and remain at approximately the electrical potential of the generator in which they were generated. The electrons migrate from the ion beam path in a precessing motion out of the ion accelerating field region into an electron recovery region provided by a specially designed electron collector electrode. The electron collector electrode is uniformly spaced from a surface of the ion generator which is transverse to the direction of migration of the electrons and the two surfaces are contoured in a matching relationship which departs from a planar configuration to provide an electric field component in the recovery region which is parallel to the magnetic field thereby forcing the electrons to be directed into and collected by the electron collector electrode. The collector electrode is maintained at a potential slightly positive with respect to the ion generator so that the electrons are collected at a small fraction of the full accelerating supply voltage energy.

  19. Positive ion polymerization in hydrogen diluted silane plasmas

    SciTech Connect

    Nunomura, S.; Kondo, M.

    2008-12-08

    Mass spectra of positive ions (cations) and neutrals have been measured in hydrogen diluted silane plasmas at gas pressures of 0.1-10 Torr. The mass spectrum of ions changes with the pressure, while that of neutrals maintains a similar shape. The dominant ion species varies from a hydrogen ion group at < or approx. 0.5 Torr to a monosilicon hydride ion group at {approx_equal}0.5-1 Torr and polysilicon hydride ion groups at > or approx. 1 Torr, which is determined from ionization channels and consecutive ion-molecule reactions. The ion bombardment is suppressed with the pressure, from several tens of eV at < or approx. 1 Torr to a few eV at > or approx. 7 Torr.

  20. Proof-of-Concept Experiments for Negative Ion Driver Beams for Heavy Ion Fusion

    SciTech Connect

    L.R. Grisham; S.K. Hahto; S.T. Hahto; J.W. Kwan; K.N. Leung

    2003-05-06

    Negative halogen ion beams have recently been proposed as heavy ion fusion drivers. They would avoid the problem of electron accumulation in positive ion beams, and could be efficiently photo-detached to neutrals if desired. Initial experiments using chlorine produced a current density of 45 mA/cm{sup 2} of 99.5% atomic negative Cl with an e/Cl- ratio as low as 7:1 and good emittance.

  1. Doubly Excited Resonances in the Positronium Negative Ion

    NASA Technical Reports Server (NTRS)

    Ho, Y.K.

    2007-01-01

    The recent theoretical studies on the doubly excited states of the Ps' ion are described. The results obtained by using the method of complex coordinate rotation show that the three-lepton system behaves very much like an XYX tri-atomic molecule. Furthermore, the recent investigation on the positronium negative ion embedded in Debye plasma environments is discussed. The problem is modeled by the use of a screened Coulomb potential to represent the interaction between the charge particles.

  2. Improvement of JT-60U Negative Ion Source Performance

    SciTech Connect

    L.R. Grisham; M. Kuriyama; M. Kawai; T. Itoh; N. Umeda; JT-60U Team

    2000-11-15

    The negative ion neutral beam system now operating on JT-60U was the first application of negative ion technology to the production of beams of high current and power for conversion to neutral beams, and has successfully demonstrated the feasibility of negative ion beam heating systems for ITER and future tokamak reactors [1, 2]. It also demonstrated significant electron heating[3] and high current drive efficiency in JT-60U[4]. Because this was such a large advance in the state of the art with respect to all system parameters, many new physical processes appeared during the earlier phases of the beam injection experiments. We have explored the physical mechanisms responsible for these processes, and implemented solutions for some of them, in particular excessive beam stripping, the secular dependence of the arc and beam parameters, and nonuniformity of the plasma illuminating the beam extraction grid. This has reduced the percentage of beam heat loading on the downstream grids by roug hly a third, and permitted longer beam pulses at higher powers. Progress is being made in improving the negative ion current density, and in coping with the sensitivity of the cesium in the ion sources to oxidation by tiny air or water leaks, and the cathode operation is being altered.

  3. Negative ion-based neutral injection on DIII-D

    SciTech Connect

    Stewart, L.D.; Bhadra, D.K.; Colleraine, A.P.; Kim, J.

    1990-01-01

    High energy negative ion-based neutral beam injection is a strong candidate for heating and non-inductive current drive in tokamaks. Many of the questions related to the physics and engineering of this technique remain unanswered. In this paper, we consider the possibility of negative ion-based neutral beam injection on DIII-D. We establish the desired parameter space by examining physics trades. This is combined with potential design constraints and a survey of component technology options to establish an injector concept. Injector performance is estimated assuming particular component technologies, and concept flexibility with respect to incorporating alternate technologies is described. 9 refs., 6 figs., 4 tabs.

  4. Solitons in a relativistic plasma with negative ions--

    SciTech Connect

    Das, G.C. ); Karmakar, B. ); Ibohanbi Singh, KH. )

    1990-02-01

    The interaction of the nonlinearity and the dispersiveness causing the solitary waves are studied in a relativistic plasma with negative ions through the derivation of a nonlinear partial differential equation known as the Korteweg-Devries (K-DV) equation. The negative ions play a salient feature on the existence and behavior of the solitons and could be of interest in laboratory plasmas. First, the observations are made in a nonisothermal plasma, and later the reduction to the nonisothermality of the plasma shows entirely different characteristics as compared to the solitons in the isothermal plasmas. A comparison with the various solutions has been emphasized.

  5. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    SciTech Connect

    Bradforth, S.E.

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound [yields] bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN[sup [minus

  6. Specific formation of negative ions from leucine and isoleucine molecules

    NASA Astrophysics Data System (ADS)

    Papp, Peter; Shchukin, Pavel; Matejčík, Štefan

    2010-01-01

    Dissociative electron attachment (DEA) to gas phase leucine (Leu) and isoleucine (Ile) molecules was studied using experimental and quantum-chemical methods. The relative partial cross sections for DEA have been measured using crossed electron/molecular beams technique. Supporting ab initio calculations of the structure, energies of neutral molecules, fragments, and negative ions have been carried out at G3MP2 and B3LYP levels in order to interpret the experimental data. Leu and Ile exhibit several common features. The negative ionic fragments from both molecules are formed in the electron energy range from 0 to approximately 14 eV via three resonances (1.2, 5.5, and 8 eV). The relative partial cross sections for DEA Leu and Ile are very similar. The dominant negative ions formed were closed shell negative ions (M-H)- (m/z=130) formed preferentially via low electron energy resonance of 1.23 eV. Additional negative ions with m/z=115, 114, 113, 112, 84, 82, 74, 45, 26, and 17 have been detected.

  7. Positive and negative cluster ions from liquid ethanol by fast ion bombardment.

    PubMed

    Kaneda, M; Shimizu, M; Hayakawa, T; Iriki, Y; Tsuchida, H; Itoh, A

    2010-04-14

    Secondary ion mass spectra have been measured for the first time for a liquid ethanol target bombarded by 2.0 MeV He(+) ions. Positive and negative ion spectra exhibit evidently a series of cluster ions of the forms [(EtOH)(n)H](+) and [(EtOH)(n)-H](-), respectively, in addition to light fragment ions from intact parent molecules. It was found that these cluster ions are produced only from liquid phase ethanol. Both positive and negative secondary ion spectra show similar cluster size distributions with almost the same decay slope. We also present for the first time the cluster ion distribution emitted from the liquid at different liquid temperatures.

  8. Significant enhancement of negative secondary ion yields by cluster ion bombardment combined with cesium flooding.

    PubMed

    Philipp, Patrick; Angerer, Tina B; Sämfors, Sanna; Blenkinsopp, Paul; Fletcher, John S; Wirtz, Tom

    2015-10-01

    In secondary ion mass spectrometry (SIMS), the beneficial effect of cesium implantation or flooding on the enhancement of negative secondary ion yields has been investigated in detail for various semiconductor and metal samples. All results have been obtained for monatomic ion bombardment. Recent progress in SIMS is based to a large extent on the development and use of cluster primary ions. In this work we show that the enhancement of negative secondary ions induced by the combination of ion bombardment with simultaneous cesium flooding is valid not only for monatomic ion bombardment but also for cluster primary ions. Experiments carried out using C60+ and Ar4000+ bombardment on silicon show that yields of negative secondary silicon ions can be optimized in the same way as by Ga+ and Cs+ bombardment. Both for monatomic and cluster ion bombardment, the optimization does not depend on the primary ion species. Hence, it can be assumed that the silicon results are also valid for other cluster primary ions and that results obtained for monatomic ion bombardment on other semiconductor and metal samples are also valid for cluster ion bombardment. In SIMS, cluster primary ions are also largely used for the analysis of organic matter. For polycarbonate, our results show that Ar4000+ bombardment combined with cesium flooding enhances secondary ion signals by a factor of 6. This can be attributed to the removal of charging effects and/or reduced fragmentation, but no major influence on ionization processes can be observed. The use of cesium flooding for the imaging of cells was also investigated and a significant enhancement of secondary ion yields was observed. Hence, cesium flooding has also a vast potential for SIMS analyses with cluster ion bombardment.

  9. Negative ion production in the RF multiaperture surface-plasma source

    SciTech Connect

    Abdrashitov, G.; Belchenko, Yu. Dranichnikov, A.; Gorbovsky, A.; Kapitonov, V.; Kolmogorov, V.; Kondakov, A.; Konstantinov, S.; Sanin, A.; Selivanov, A.; Selivanov, P.; Shikhovtsev, I.; Stupishin, N.; Tiunov, M.; Ivanov, A.; Sotnikov, O.; Binderbauer, M.; Putvinski, S.; Smirnov, A.; Sevier, L.

    2015-04-08

    The experiments on negative hydrogen ion beam production in a multi-aperture long-pulse surface-plasma source are described. H- ions are produced on the surface of a plasma grid covered by cesium and illuminated by fast plasma particles. The source uses a radio-frequency driver to generate plasma. A composite magnet system made of external permanent magnets confines and filters electrons in the plasma region, and deflects them in the extraction area. A multiaperture, multi-electrode ion optical system is used for beam formation. The electrode heating and cooling during long pulses is accomplished by circulating a heat transfer fluid through channels drilled in the electrodes bodies. H- ions extraction through a single aperture and 21 apertures was performed and studied. A stable H- beam with the current up to 0.7 A, energy up to 74 kV, and pulse duration up to 7 s was routinely obtained.

  10. Recent advancements in sputter-type heavy negative ion sources

    SciTech Connect

    Alton, G.D.

    1989-01-01

    Significant advancement have been made in sputter-type negative ion sources which utilize direct surface ionization, or a plasma to form the positive ion beam used to effect sputtering of samples containing the material of interest. Typically, such sources can be used to generate usable beam intensities of a few ..mu..A to several mA from all chemically active elements, depending on the particular source and the electron affinity of the element in question. The presentation will include an introduction to the fundamental processes underlying negative ion formation by sputtering from a low work function surface and several sources will be described which reflect the progress made in this technology. 21 refs., 9 figs., 1 tab.

  11. Space Charge Neutralization in the ITER Negative Ion Beams

    SciTech Connect

    Surrey, Elizabeth

    2007-08-10

    A model of the space charge neutralization of negative ion beams, developed from the model due to Holmes, is applied to the ITER heating and diagnostic beams. The Holmes model assumed that the plasma electron temperature was derived from the stripped electrons. This is shown to be incorrect for the ITER beams and the plasma electron temperature is obtained from the average creation energy upon ionization. The model shows that both ITER beams will be fully space charge compensated in the drift distance between the accelerator and the neutralizer. Inside the neutralizer, the plasma over compensates the space charge to the extent that a significant focusing force is predicted. At a certain position in the neutraliser this force balances the defocusing force due to the ions' transverse energy. Under these conditions the beam distribution function can change from Gaussian to Bennett and evidence of such a distribution observed in a multi-aperture, neutralized negative ion beam is presented.

  12. Effects of adsorption and roughness upon the collision processes at the convertor surface of a plasma sputter negative ion source

    SciTech Connect

    Kenmotsu, T.; Wada, M.

    2012-02-15

    Atomic collision processes associated with surface production of negative hydrogen ions (H{sup -}) by particle reflection at molybdenum surface immersed in hydrogen plasma have been investigated. To calculate sputtering yields of Cs, as well as energy spectra and angular distributions of reflected hydrogen atoms from molybdenum surface by H{sup +} ion and Cs{sup +} ion bombardments, a Monte Carlo simulation code ACAT (Atomic Collision in Amorphous Target) was run with the corresponding surface conditions. A fractal surface model has been developed and adopted to ACAT for evaluating the effect due to roughness of target material. The results obtained with ACAT have indicated that the retention of hydrogen atoms leads to the reduction in sputtering yields of Cs, and the surface roughness does largely affect the sputtering yields of Cs.

  13. Transport Properties of Negative Ions in HBR Plasmas

    NASA Astrophysics Data System (ADS)

    Stojanovic, Vladimir; Ivanovic, Nenad; Radmilovic-Radjenovic, Marija; Raspopovic, Zoran; Bojarov, Aleksandar; Petrovic, Zoran

    2014-10-01

    Low temperature plasma in halogenated gases is standard environment for dry etching of semiconductors. Amount of negative ions in HBr plasmas determines electronegativity so modeling etching devices requires data for anion transport properties. In this work we present cross section set for Br- ions in HBr assembled by using Denpoh-Nanbu theory. The threshold energy values were calculated by known heats of formation. The calculated total cross section accounts for ion-induced-dipole and ion-permanent-dipole interaction by using the local-dipole model. The total cross section was corrected to fit the reduced mobility obtained by SACM (Statistical Adiabatic Channel Model) approximation. Existing cross section measurements were used to scale calculated cross sections. Finally, we used Monte Carlo method to determine transport parameters for Br- as a function of reduced electric fields that can be used in fluid and hybrid plasma models.

  14. Hydrogen Reduction of Ferric Ions for Use in Copper Electrowinning

    SciTech Connect

    Karl S. Noah; Debby F. Bruhn; John E. Wey; Robert S. Cherry

    2005-01-01

    The conventional copper electrowinning process uses the water hydrolysis reaction as the anodic source of electrons. However this reaction generates acid mist and requires large quantities of energy. In order to improve energy efficiency and avoid acid mist, an alternative anodic reaction of ferrous ion oxidation has been proposed. This reaction does not involve evolution of acid mist and can be carried out at a lower cell voltage than the conventional process. However, because ferrous ions are converted to ferric ions at the anode in this process, there is a need for reduction of ferric ions to ferrous ions to continue this process. The most promising method for this reduction is the use of hydrogen gas since the resulting byproduct acid can be used elsewhere in the process and, unlike other reductants, hydrogen does not introduce other species that need subsequent removal. Because the hydrogen reduction technology has undergone only preliminary lab scale testing, additional research is needed to evaluate its commercial potential. Two issues for this research are the potentially low mass transfer rate of hydrogen into the electrolyte stream because of its low solubility in water, and whether other gaseous reductants less expensive than hydrogen, such as natural gas or syngas, might work. In this study various reductants were investigated to carry out the reduction of ferric ions to ferrous ions using a simulated electrolyte solution recycled through a trickle bed reactor packed with catalyst. The gases tested as reductants were hydrogen, methane, carbon monoxide, and a 50/50 mixture of H2 and CO. Nitrogen was also tested as an inert control. These gases were tested because they are constituents in either natural gas or syngas. The catalysts tested were palladium and platinum. Two gas flow rates and five electrolyte flow rates were tested. Pure hydrogen was an effective reductant of ferric ion. The rates were similar with both palladium and platinum. The ferric

  15. Hydrogen ion diffusion coefficient of silicon nitride thin films

    NASA Astrophysics Data System (ADS)

    Yu, George T.; Yen, S. K.

    2002-12-01

    Hydrogen ion diffusion in silicon nitride thin film is of significant interest because of its importance in barrier, sensor and catalytic coating applications. In this study, a novel method based on potential-pH response measurement was used to determine hydrogen ion diffusion in silicon nitride thin films. Hydrogen ion diffusion coefficient in silicon nitride films obtained from this method was 1×10 -19 cm 2/s. A potential-pH response drift was observed and is believed to be due to the presence of a hydrated layer affecting the hydrogen ion diffusion onto the nitride film of the Si 3N 4-gate hydrogen ion-sensitive field effect transistors (ISFETs). The unique feature of the potential-pH response method is its relatively simple experimental procedure, which eliminates complications arising from surface-related effects and/or presence of hydrogen traps in membrane, such as those found in the conventional permeation method. The method also offers a considerable test time reduction, with the experiment being completed in 10 h as compared to the conventional electrochemical permeation method which takes as long as 5 days.

  16. Multi-dipolar microwave plasmas and their application to negative ion production

    SciTech Connect

    Béchu, S.; Bès, A.; Lacoste, A.; Aleiferis, S.; Ivanov, A. A. Jr.; Bacal, M.

    2013-10-15

    During the past decade multi-dipolar plasmas have been employed for various purposes such as surface treatments in biomedicine, physical and chemical vapour deposition for hydrogen storage, and applications in mechanical engineering. On the other hand, due to the design and operational mode of these plasma sources (i.e., strong permanent magnets for the electron cyclotron resonance coupling, low working pressure, and high electron density achieved) they are suitable for studying fundamental mechanisms involved in negative ion sources used in magnetically confined fusion and particle accelerators. Thus, this study presents an overview of fundamental results obtained with: (i) a single dipolar source, (ii) a network of seven dipolar plasma sources inserted into a magnetic multipolar chamber (Camembert III), and (iii) four dipolar sources housed in a smaller metallic cylinder (ROSAE III). Investigations with Langmuir probes of electron energy probability functions revealed the variation of the plasma properties versus the radial distance from the axis of a dipolar source in its mid plane and allowed the determination of the proportion between hot and cold electron populations in both chambers. These results are compared with the density of hydrogen negative ions, measured using the photodetachment technique. Electron energy probability functions obtained in these different configurations show the possibility of both hot and cold electron production. The former is a prerequisite for increasing the vibrational level of molecules and the dissociation degree and the latter for producing negative ions via dissociative attachment of the cold electrons or via surface production induced by H atoms.

  17. Development of negative ion extractor in the high-power and long-pulse negative ion source for fusion application

    SciTech Connect

    Kashiwagi, M. Umeda, N.; Tobari, H.; Kojima, A.; Yoshida, M.; Taniguchi, M.; Dairaku, M.; Maejima, T.; Yamanaka, H.; Watanabe, K.; Inoue, T.; Hanada, M.

    2014-02-15

    High power and long-pulse negative ion extractor, which is composed of the plasma grid (PG) and the extraction grid (EXG), is newly developed toward the neutral beam injector for heating and current drive of future fusion machines such as ITER, JT-60 Super Advanced and DEMO reactor. The PG is designed to enhance surface production of negative ions efficiently by applying the chamfered aperture. The efficiency of the negative ion production for the discharge power increased by a factor of 1.3 against that of the conventional PG. The EXG is also designed with the thermal analysis to upgrade the cooling capability for the long pulse operation of >1000 s required in ITER. Though the magnetic field for electron suppression is reduced to 0.75 of that in the conventional EXG due to this upgrade, it was experimentally confirmed that the extracted electron current can be suppressed to the allowable level for the long pulse operation. These results show that newly developed extractor has the high potential for the long pulse extraction of the negative ions.

  18. Challenges in plasma and extraction modelling of negative ion sources

    NASA Astrophysics Data System (ADS)

    Kalvas, Taneli

    2013-09-01

    The physical processes taking place in negative ion source plasmas are modelled by state-of-the-art 3D particle-in-cell (PIC) codes. These codes are used to gain understanding and to find optimal solutions for negative ion beam production. The PIC codes can be made to match to the reality if all relevant processes were included. This is unfortunately limited by the availability of data about the processes and the huge amount of computational resources needed for the simulations. The optimization of the extraction system and beam transport ion optics is often made using computationally less intensive methods utilized in so-called gun codes. These codes use simplified plasma models to provide a starting point for the extracted beams being simulated. The relatively fast computation allows systematic studies, which are not practical with PIC codes. The gun codes often match well to reality, but they do have difficulties reproducing some effects, especially in negative ion extraction, due to the approximations made in the plasma model. Could the future solutions for beam production modelling couple the two types of simulations?

  19. Small radio frequency driven multicusp ion source for positive hydrogen ion beam production

    SciTech Connect

    Perkins, L.T.; Herz, P.R.; Leung, K.N.; Pickard, D.S. )

    1994-04-01

    A compact, 2.5 cm diam rf-driven multicusp ion source has been developed and tested for H[sup +] ion production in pulse mode operation. The source is optimized for atomic hydrogen ion species and extractable current. It is found that hydrogen ion beam current densities in excess of 650 mA/cm[sup 2] can be achieved with H[sup +] species above 80%. The geometry and position of the porcelain-coated copper antenna were found to be of great significance in relation to the efficiency of the ion source.

  20. Strong Turbulence in Alkali Halide Negative Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Sheehan, Daniel

    1999-11-01

    Negative ion plasmas (NIPs) are charge-neutral plasmas in which the negative charge is dominated by negative ions rather than electrons. They are found in laser discharges, combustion products, semiconductor manufacturing processes, stellar atmospheres, pulsar magnetospheres, and the Earth's ionosphere, both naturally and man-made. They often display signatures of strong turbulence^1. Development of a novel, compact, unmagnetized alkali halide (MX) NIP source will be discussed, it incorporating a ohmically-heated incandescent (2500K) tantulum solenoid (3cm dia, 15 cm long) with heat shields. The solenoid ionizes the MX vapor and confines contaminant electrons, allowing a very dry (electron-free) source. Plasma densities of 10^10 cm-3 and positive to negative ion mass ratios of 1 <= fracm_+m- <= 20 are achievable. The source will allow tests of strong turbulence theory^2. 1 Sheehan, D.P., et al., Phys. Fluids B5, 1593 (1993). 2 Tsytovich, V. and Wharton, C.W., Comm. Plasma Phys. Cont. Fusion 4, 91 (1978).

  1. Power supply system for negative ion source at IPR

    NASA Astrophysics Data System (ADS)

    Gahlaut, Agrajit; Sonara, Jashwant; Parmar, K. G.; Soni, Jignesh; Bandyopadhyay, M.; Singh, Mahendrajit; Bansal, Gourab; Pandya, Kaushal; Chakraborty, Arun

    2010-02-01

    The first step in the Indian program on negative ion beams is the setting up of Negative ion Experimental Assembly - RF based, where 100 kW of RF power shall be coupled to a plasma source producing plasma of density ~5 × 1012 cm-3, from which ~ 10 A of negative ion beam shall be produced and accelerated to 35 kV, through an electrostatic ion accelerator. The experimental system is modelled similar to the RF based negative ion source, BATMAN presently operating at IPP, Garching, Germany. The mechanical system for Negative Ion Source Assembly is close to the IPP source, remaining systems are designed and procured principally from indigenous sources, keeping the IPP configuration as a base line. High voltage (HV) and low voltage (LV) power supplies are two key constituents of the experimental setup. The HV power supplies for extraction and acceleration are rated for high voltage (~15 to 35kV), and high current (~ 15 to 35A). Other attributes are, fast rate of voltage rise (< 5ms), good regulation (< ±1%), low ripple (< ±2%), isolation (~50kV), low energy content (< 10J) and fast cut-off (< 100μs). The low voltage (LV) supplies required for biasing and providing heating power to the Cesium oven and the plasma grids; have attributes of low ripple, high stability, fast and precise regulation, programmability and remote operation. These power supplies are also equipped with over-voltage, over-current and current limit (CC Mode) protections. Fault diagnostics, to distinguish abnormal rise in currents (breakdown faults) with over-currents is enabled using fast response breakdown and over-current protection scheme. To restrict the fault energy deposited on the ion source, specially designed snubbers are implemented in each (extraction and acceleration) high voltage path to swap the surge energy. Moreover, the monitoring status and control signals from these power supplies are required to be electrically (~ 50kV) isolated from the system. The paper shall present the

  2. Design of a cavity ring-down spectroscopy diagnostic for negative ion rf source SPIDER

    SciTech Connect

    Pasqualotto, R.; Alfier, A.; Lotto, L.

    2010-10-15

    The rf source test facility SPIDER will test and optimize the source of the 1 MV neutral beam injection systems for ITER. Cavity ring-down spectroscopy (CRDS) will measure the absolute line-of-sight integrated density of negative (H{sup -} and D{sup -}) ions, produced in the extraction region of the source. CRDS takes advantage of the photodetachment process: negative ions are converted to neutral hydrogen atoms by electron stripping through absorption of a photon from a laser. The design of this diagnostic is presented with the corresponding simulation of the expected performance. A prototype operated without plasma has provided CRDS reference signals, design validation, and results concerning the signal-to-noise ratio.

  3. Oscillatory instability development in extraction system of a negative ion source.

    PubMed

    Barminova, H Y; Chikhachev, A S

    2016-02-01

    Conditions of oscillatory instability development in the extraction system of a negative hydrogen ion source based on a volume-produced plasma are studied. Such an ion source is characterized by the presence of the parent gas in the extraction system due to the leakage from the gas-discharge chamber. The secondary electrons in the area of the ion-optical system become the reason of oscillation appearance and possible beam current modulation. Analytically the range of the stable beam propagation is found. The instability increment is shown to be rather small. Maximum increment of the oscillations corresponds to the beam velocity equal to the thermal velocity of plasma electrons. The group velocity of the oscillations is close to the beam velocity so the oscillations are convective. Simulation of the low energy beam propagation is performed in COMSOL Multiphysics, the beam current modulation being observed. PMID:26931916

  4. Theory and observation of a dynamically evolviong negative ion plasma

    SciTech Connect

    Mendillo, M.; Forbes, J.

    1982-10-01

    As part of the Project Firefly ionospheric modification campaigns conducted during the early 1960's, sulfur hexafluoride (SF/sub 6/) was used to study the creation and consequences of artificially-induced electron depletion regions via the attachment process (SF/sub 6/+e..-->..SF/sub 6/). Since those early experiments, a great many advances have occurred in theoretical, laboratory, and diagnostic techniques related to negative ion plasmas. This study examines the full range of negative ion chemistry in the upper ionosphere by using current reaction rate data to investigate the many chemical paths SF/sub 6/ type injections might take in an F region environment. Particular attention is given to the conditions required to create heavy negative ions that persist long enough to affect the dynamical properties of the F region. The ambipolar diffusion characteristics of a three component plasma (O/sup +/, e/sup -/, SF/sub 6//sup -/) are described, and estimates of the incoherent scatter spectra obtained from such a plasma are presented. Model calculations using a first order chemical code are defined and tested to investigate the actual types of negative ion plasmas capable of being created under nighttime conditions. A versatile model for diffusion in an exponential atmosphere ws used to simulate the evolution of 10/sup 26/SF/sub 6/ molecules released at 222 km during a 1962 Firefly experiment. When examined in conjunction with the chemical model calculatins, the results suggest that the ionospheric perturbations recorded at the time probably resulted more from molecular and atomic ion neutralizations involving SF/sub 6//sup -/, SF/sub 5//sup +/, O/sup -/, O/sup +/, and epsilon/sup -/, rather than simple electron attachments, as had been expected. A similar use of SF/sub 6/ diffusion scenarios for high-altitude releases (h = 350-500 km) indicates that large-scale, long-lived negative ion plasmas could be produced by modest rocket or Shuttle-borne payloads to study

  5. Inner-shell photodetachment of transition metal negative ions

    NASA Astrophysics Data System (ADS)

    Dumitriu, Ileana

    This thesis focuses on the study of inner-shell photodetachment of transition metal negative ions, specifically Fe- and Ru- . Experimental investigations have been performed with the aim of gaining new insights into the physics of negative atomic ions and providing valuable absolute cross section data for astrophysics. The experiments were performed using the X-ray radiation from the Advanced Light Source, Lawrence Berkeley National Laboratory, and the merged-beam technique for photoion spectroscopy. Negative ions are a special class of atomic systems very different from neutral atoms and positive ions. The fundamental physics of the interaction of transition metal negative ions with photons is interesting but difficult to analyze in detail because the angular momentum coupling generates a large number of possible terms resulting from the open d shell. Our work reports on the first inner-shell photodetachment studies and absolute cross section measurements for Fe- and Ru -. In the case of Fe-, an important astrophysical abundant element, the inner-shell photodetachment cross section was obtained by measuring the Fe+ and Fe2+ ion production over the photon energy range of 48--72 eV. The absolute cross sections for the production of Fe+ and Fe2+ were measured at four photon energies. Strong shape resonances due to the 3p→3d photoexcitation were measured above the 3p detachment threshold. The production of Ru+, Ru2+, and Ru3+ from Ru- was measured over 30--90 eV photon energy range The absolute photodetachment cross sections of Ru - ([Kr] 4d75s 2) leading to Ru+, Ru2+, and Ru 3+ ion production were measured at three photon energies. Resonance effects were observed due to interference between transitions of the 4 p-electrons to the quasi-bound 4p54d85s 2 states and the 4d→epsilonf continuum. The role of many-particle effects, intershell interaction, and polarization seems much more significant in Ru- than in Fe- photodetachment.

  6. Reflection of ion acoustic solitons in a plasma having negative ions

    SciTech Connect

    Chauhan, S.S.; Malik, H.K.; Dahiya, R.P.

    1996-11-01

    Reflection of compressive and rarefactive ion acoustic solitons propagating in an inhomogeneous plasma in the presence of negative ions is investigated. Modified Korteweg{endash}deVries equations for incident and reflected solitons are derived and solved. The amplitude of incident and reflected solitons increases with negative to positive ion density ratio. With increasing density ratio, reflection of rarefactive solitons is reinforced whereas that of compressive solitons weakened. The rarefactive solitons are found to undergo stronger reflection than the compressive ones. {copyright} {ital 1996 American Institute of Physics.}

  7. Radiocarbon dating using electrostatic accelerators: negative ions provide the key.

    PubMed

    Bennett, C L; Beukens, R P; Clover, M R; Gove, H E; Liebert, R B; Litherland, A E; Purser, K H; Sondheim, W E

    1977-11-01

    Mass spectrometric methods have long been suggested as ways of measuring (14)C/(12)C ratios for carbon dating. One problem has been to distinguish between (14)N and (14)C. With negative ions and a tandem electrostatic accelerator, the (14)N background is virtually absent and fewer than three (14)C atoms in 10(16) atoms of (12)C have been easily measured.

  8. Gabor lens focusing of a negative ion beam

    SciTech Connect

    Palkovic, J.A.; Mills, F.E.; Schmidt, C.; Young, D.E.

    1989-05-01

    Gabor or plasma lenses have previously been used to focus intense beams of positive ions at energies from 10 keV to 5 MeV. It is the large electrostatic field of the non-neutral plasma in the Gabor lens which is responsible for the focusing. Focusing an ion beam with a given sign of charge in a Gabor lens requires a non-neutral plasma with the opposite sign of charge as the beam. A Gabor lens constructed at Fermilab has been used to focus a 30 keV proton beam with good optical quality. We discuss studies of the action of a Gabor lens on a beam of negative ions. A Gabor lens has been considered for matching an H/sup /minus// beam into an RFQ in the redesign of the low energy section of the Fermilab linac. 9 refs., 3 figs., 1 tab.

  9. Observation of a shape resonance of the positronium negative ion

    NASA Astrophysics Data System (ADS)

    Michishio, Koji; Kanai, Tsuneto; Kuma, Susumu; Azuma, Toshiyuki; Wada, Ken; Mochizuki, Izumi; Hyodo, Toshio; Yagishita, Akira; Nagashima, Yasuyuki

    2016-03-01

    When an electron binds to its anti-matter counterpart, the positron, it forms the exotic atom positronium (Ps). Ps can further bind to another electron to form the positronium negative ion, Ps- (e-e+e-). Since its constituents are solely point-like particles with the same mass, this system provides an excellent testing ground for the three-body problem in quantum mechanics. While theoretical works on its energy level and dynamics have been performed extensively, experimental investigations of its characteristics have been hampered by the weak ion yield and short annihilation lifetime. Here we report on the laser spectroscopy study of Ps-, using a source of efficiently produced ions, generated from the bombardment of slow positrons onto a Na-coated W surface. A strong shape resonance of 1Po symmetry has been observed near the Ps (n=2) formation threshold. The resonance energy and width measured are in good agreement with the result of three-body calculations.

  10. Time-fractional Gardner equation for ion-acoustic waves in negative-ion-beam plasma with negative ions and nonthermal nonextensive electrons

    SciTech Connect

    Guo, Shimin Mei, Liquan; Zhang, Zhengqiang

    2015-05-15

    Nonlinear propagation of ion-acoustic waves is investigated in a one-dimensional, unmagnetized plasma consisting of positive ions, negative ions, and nonthermal electrons featuring Tsallis distribution that is penetrated by a negative-ion-beam. The classical Gardner equation is derived to describe nonlinear behavior of ion-acoustic waves in the considered plasma system via reductive perturbation technique. We convert the classical Gardner equation into the time-fractional Gardner equation by Agrawal's method, where the time-fractional term is under the sense of Riesz fractional derivative. Employing variational iteration method, we construct solitary wave solutions of the time-fractional Gardner equation with initial condition which depends on the nonlinear and dispersion coefficients. The effect of the plasma parameters on the compressive and rarefactive ion-acoustic solitary waves is also discussed in detail.

  11. Evaluation of Negative-Ion-Beam Driver Concepts for Heavy Ion Fusion

    SciTech Connect

    Grisham, Larry R.

    2003-03-15

    The feasibility of producing and using atomically neutral heavy ion beams produced from negative ions as drivers for an inertial confinement fusion reactor is evaluated. Bromine and iodine appear to be the most attractive elements for the driver beams. Fluorine and chlorine appear to be the most appropriate feedstocks for initial tests of extractable negative-ion current densities. With regard to ion sources, photodetachment neutralizers, and vacuum requirements for accelerators and beam transport, this approach appears feasible within existing technology, and the vacuum requirements are essentially identical to those for positive-ion drivers except in the target chamber. The principal constraint is that this approach requires harder vacuums in the target chamber than do space-charge-neutralized positive-ion drivers. With realistic (but perhaps pessimistic) estimates of the total ionization cross section, limiting the ionization of a neutral beam to <5% while traversing a 3-m path would require a chamber pressure of no more than 1.3 x 10{sup -5} torr. However, it appears that substantial improvements in the beam spot size on target might be achieved at pressures a factor of 10 or more higher than this. Alternatively, even at still higher chamber pressures that would strongly ionize atomically neutral beams, the negative-ion approach may still have significant appeal, since it precludes the possibly challenging problem of electron contamination of a positive-ion beam during acceleration, drift compression, and focusing.

  12. Evaluation of Negative-Ion-Beam Driver Concepts for Heavy Ion Fusion

    SciTech Connect

    Larry R. Grisham

    2002-01-14

    We evaluate the feasibility of producing and using atomically neutral heavy ion beams produced from negative ions as drivers for an inertial confinement fusion reactor. Bromine and iodine appear to be the most attractive elements for the driver beams. Fluorine and chlorine appear to be the most appropriate feedstocks for initial tests of extractable negative ion current densities. With regards to ion sources, photodetachment neutralizers, and vacuum requirements for accelerators and beam transport, this approach appears feasible within existing technology, and the vacuum requirements are essentially identical to those for positive ion drivers except in the target chamber. The principal constraint is that this approach requires harder vacuums in the target chamber than do space-charge-neutralized positive ion drivers. With realistic (but perhaps pessimistic) estimates of the total ionization cross section, limiting the ionization of a neutral beam to less than 5% while traversing a four -meter path would require a chamber pressure of no more than 5 x 10{sup -5} torr. Alternatively, even at chamber pressures that are too high to allow propagation of atomically neutral beams, the negative ion approach may still have appeal, since it precludes the possibly serious problem of electron contamination of a positive ion beam during acceleration, drift compression, and focusing.

  13. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen... used to measure, in vivo, the hydrogen ion concentration (pH) in blood to aid in determining...

  14. Periodic orbits of the hydrogen molecular ion and their quantization

    SciTech Connect

    Duan, Y.; Yuan, J.; Bao, C.

    1995-11-01

    In a classical study of the hydrogen molecular ion beyond the Born-Oppenheimer approximation (BOA), we have found that segments of trajectories resemble that of the Born-Oppenheimer approximation periodic orbits. The importance of this fact to the classical understanding of chemical bonding leads us to a systematic study of the periodic orbits of the planar hydrogen molecular ion within the BOA. Besides introducing a classification scheme for periodic orbits, we discuss the convergence properties of families of periodic orbits and their bifurcation patterns according to their types. Semiclassical calculations of the density of states based on these periodic orbits yield results in agreement with the exact quantum eigenvalues of the hydrogen molecular ion system.

  15. Helium-ion-induced release of hydrogen from graphite

    SciTech Connect

    Langley, R.A.

    1987-01-01

    The ion-induced release of hydrogen from AXF-5Q graphite was studied for 350-eV helium ions. The hydrogen was implanted into the graphite with a low energy (approx.200 eV) and to a high fluence. This achieved a thin (approx.10-nm), saturated near-surface region. The release of hydrogen was measured as a function of helium fluence. A model that includes ion-induced detrapping, retrapping, and surface recombination was used to analyze the experimental data. A value of (1.65 +- 0.2) x 10/sup -16/ cm/sup 2/ was obtained from the detrapping cross section, and a value of (0.5 to 4) x 10/sup -14/ cm/sup 4//atoms was obtained for the recombination coefficient. 11 refs., 4 figs.

  16. Semiempirical Theories of the Affinities of Negative Atomic Ions

    NASA Technical Reports Server (NTRS)

    Edie, John W.

    1961-01-01

    The determination of the electron affinities of negative atomic ions by means of direct experimental investigation is limited. To supplement the meager experimental results, several semiempirical theories have been advanced. One commonly used technique involves extrapolating the electron affinities along the isoelectronic sequences, The most recent of these extrapolations Is studied by extending the method to Include one more member of the isoelectronic sequence, When the results show that this extension does not increase the accuracy of the calculations, several possible explanations for this situation are explored. A different approach to the problem is suggested by the regularities appearing in the electron affinities. Noting that the regular linear pattern that exists for the ionization potentials of the p electrons as a function of Z, repeats itself for different degrees of ionization q, the slopes and intercepts of these curves are extrapolated to the case of the negative Ion. The method is placed on a theoretical basis by calculating the Slater parameters as functions of q and n, the number of equivalent p-electrons. These functions are no more than quadratic in q and n. The electron affinities are calculated by extending the linear relations that exist for the neutral atoms and positive ions to the negative ions. The extrapolated. slopes are apparently correct, but the intercepts must be slightly altered to agree with experiment. For this purpose one or two experimental affinities (depending on the extrapolation method) are used in each of the two short periods. The two extrapolation methods used are: (A) an isoelectronic sequence extrapolation of the linear pattern as such; (B) the same extrapolation of a linearization of this pattern (configuration centers) combined with an extrapolation of the other terms of the ground configurations. The latter method Is preferable, since it requires only experimental point for each period. The results agree within

  17. Transition of ion-acoustic perturbations in multicomponent plasma with negative ions

    SciTech Connect

    Sharma, Sumita Kumari; Devi, Kavita; Adhikary, Nirab Chandra; Bailung, Heremba

    2008-08-15

    Evolution of ion-acoustic compressive (positive) and rarefactive (negative) perturbations in a multicomponent plasma with negative ions has been investigated in a double plasma device. Transition of compressive solitons in electron-positive ion plasma, into a dispersing train of oscillations in a multicomponent plasma, when the negative ion concentration r exceeds a critical value r{sub c}, has been observed. On the other hand, an initial rarefactive perturbation initially evolves into a dispersing train of oscillations in electron-positive ion plasma and transforms into rarefactive solitons in a multicomponent plasma when the negative ion concentration is higher than the critical value. The Mach velocity and width of the compressive and rarefactive solitons are measured. The compressive solitons in the range 0r{sub c} have different characteristics than the Korteweg-de Vries (KdV) solitons at r=0 and modified KdV solitons at r=r{sub c}. A nonlinear differential equation having two terms to account for the lower and higher order nonlinearity has been used to explain the observed results.

  18. Metal negative ion beam extraction from a radio frequency ion source

    SciTech Connect

    Kanda, S.; Yamada, N.; Kasuya, T.; Romero, C. F. P.; Wada, M.

    2015-04-08

    A metal ion source of magnetron magnetic field geometry has been designed and operated with a Cu hollow target. Radio frequency power at 13.56 MHz is directly supplied to the hollow target to maintain plasma discharge and induce self-bias to the target for sputtering. The extraction of positive and negative Cu ion beams have been tested. The ion beam current ratio of Cu{sup +} to Ar{sup +} has reached up to 140% when Ar was used as the discharge support gas. Cu{sup −} ion beam was observed at 50 W RF discharge power and at a higher Ar gas pressure in the ion source. Improvement of poor RF power matching and suppression of electron current is indispensable for a stable Cu{sup −} ion beam production from the source.

  19. Improved ion implant fluence uniformity in hydrogen enhanced glow discharge plasma immersion ion implantation into silicon

    SciTech Connect

    Luo, J.; Li, L. H. E-mail: paul.chu@cityu.edu.hk; Liu, H. T.; Xu, Y.; Zuo, X. J.; Zhu, P. Z.; Ma, Y. F.; Yu, K. M.; Fu, Ricky K. Y.; Chu, Paul K. E-mail: paul.chu@cityu.edu.hk

    2014-06-15

    Enhanced glow discharge plasma immersion ion implantation does not require an external plasma source but ion focusing affects the lateral ion fluence uniformity, thereby hampering its use in high-fluence hydrogen ion implantation for thin film transfer and fabrication of silicon-on-insulator. Insertion of a metal ring between the sample stage and glass chamber improves the ion uniformity and reduces the ion fluence non-uniformity as the cathode voltage is raised. Two-dimensional multiple-grid particle-in-cell simulation confirms that the variation of electric field inside the chamber leads to mitigation of the ion focusing phenomenon and the results are corroborated experimentally by hydrogen forward scattering.

  20. The development of the radio frequency driven negative ion source for neutral beam injectors (invited)a)

    NASA Astrophysics Data System (ADS)

    Kraus, W.; Fantz, U.; Franzen, P.; Fröschle, M.; Heinemann, B.; Riedl, R.; Wünderlich, D.

    2012-02-01

    Large and powerful negative hydrogen ion sources are required for the neutral beam injection (NBI) systems of future fusion devices. Simplicity and maintenance-free operation favors RF sources, which are developed intensively at the Max-Planck-Institut für Plasmaphysik (IPP) since many years. The negative hydrogen ions are generated by caesium-enhanced surface conversion of atoms and positive ions on the plasma grid surface. With a small scale prototype the required high ion current density and the low fraction of co-extracted electrons at low pressure as well as stable pulses up to 1 h could be demonstrated. The modular design allows extension to large source dimensions. This has led to the decision to choose RF sources for the NBI of the international fusion reactor, ITER. As an intermediate step towards the full size ITER source at IPP, the development will be continued with a half-size source on the new ELISE testbed. This will enable to gain experience for the first time with negative hydrogen ion beams from RF sources of these dimensions.

  1. Detection of negative pickup ions at Saturn's moon Dione

    NASA Astrophysics Data System (ADS)

    Nordheim, T.; Jones, G. H.; Coates, A. J.; Wellbrock, A.; Hand, K. P.; Waite, J. H., Jr.

    2015-12-01

    Negative ions may be formed in both tenuous and dense planetary atmospheres and have been observed in-situ at Earth, Titan [Coates et al., 2007, 2009; Wellbrock et al., 2013] and Enceladus [Coates et al., 2010] as well as at comet Halley [Chaizy et al., 1991]. In the case of Titan, heavy hydrocarbon and nitrile based ions with masses reaching almost 14,000 amu/q have been observed using the CAPS Electron Spectrometer (ELS) onboard Cassini. These are believed to form even more massive organic aerosols termed tholins which fall to lower altitudes where they make up the distinct haze layers, and eventually rain down onto Titan's surface perhaps forming the organic-rich dunes. Very tenuous atmospheres were predicted at the smaller icy moons of Saturn [Sittler et al., 2004; Saur and Strobel, 2005], and subsequently detected [Teolis et al., 2010; Tokar et al., 2012]. These are produced when charged particles from Saturn's magnetosphere interact with moon surfaces, ejecting neutral species. Some portion of these atmospheric neutrals will in turn become ionized and 'picked up' by Saturn's corotating magnetosphere. These pickup ions will then move in cycloidal trajectories that we may intercept using the Cassini spacecraft, even at considerable distance from the moon itself. In this fashion, negative and positive pickup ions have been used to infer a tenuous CO2-O2 atmosphere at Saturn's moon Rhea [Teolis et al., 2010], and positive pickup ions at Dione [Tokar et al., 2012]. Here we report on the detection of negative pickup ions during a close flyby of Dione by the Cassini CAPS ELS instrument, and the implications that these observations may have for the Dionian atmosphere. Chaizy, P., et al. (1991), Nature, 349(6308), 393-396 Coates, A. J., et al. (2007), Geophys. Res. Lett., 34(22), 6-11 Coates, A. J., et al. (2009), Planet. Space Sci., 57(14-15), 1866-1871 Coates, A. J., et al. (2010), Icarus, 206(2), 618-622 Saur, J., and D. F. Strobel (2005), Astrophys. J. Lett., 620

  2. Wigner time delay in photodetachment of negative ions

    NASA Astrophysics Data System (ADS)

    Saha, S.; Deshmukh, P. C.; Jose, J.; Kkeifets, A. S.; Manson, S. T.

    2016-05-01

    In recent years, there has been much interest in studies on Wigner time delay in atomic photoionization using various experimental techniques and theoretical methodologies. In the present work, we report time delay in the photodetachment of negative ions using the relativistic-random-phase approximation (RRPA), which includes relativistic and important correlation effects. Time delay is obtained as energy derivative of phase of the photodetachment complex transition amplitude. We investigate the time delay in the dipole n p --> ɛd channels in the photodetachment of F- and Cl-, and in n f --> ɛg channels in the photodetachment of Tm-. In photodetachment of the negative ions, the photoelectron escapes in the field of the neutral atom and thus does not experience the nuclear Coulomb field; hence the phase is devoid of the Coulomb component. The systems chosen are well suited to examine the sensitivity of the photodetachment time delay to the centrifugal potential. The ions chosen have closed shells, and thus amenable to the RPA. Work supported by DOE, Office of Chemical Sciences, DST (India), and the Australian Research Council.

  3. Positive and negative ion beam merging system for neutral beam production

    DOEpatents

    Leung, Ka-Ngo; Reijonen, Jani

    2005-12-13

    The positive and negative ion beam merging system extracts positive and negative ions of the same species and of the same energy from two separate ion sources. The positive and negative ions from both sources pass through a bending magnetic field region between the pole faces of an electromagnet. Since the positive and negative ions come from mirror image positions on opposite sides of a beam axis, and the positive and negative ions are identical, the trajectories will be symmetrical and the positive and negative ion beams will merge into a single neutral beam as they leave the pole face of the electromagnet. The ion sources are preferably multicusp plasma ion sources. The ion sources may include a multi-aperture extraction system for increasing ion current from the sources.

  4. Probing the hydrogen exosphere of Mars with ion cyclotron waves

    NASA Astrophysics Data System (ADS)

    Wei, H. Y.; Cowee, M. M.; Russell, C. T.

    2013-09-01

    Ion cyclotron waves are generated during the interaction between the solar wind and the Martian exosphere. When the atmospheric neutrals are ionized in the solar wind, the fresh ions are accelerated by the electric field and gyrate around the magnetic field in the solar wind, in a process called ion pick-up. As the ions gyrate, ion cyclotron waves grow from the free energy of the highly anisotropic distribution of these fresh ions, with left-handed polarization and a wave frequency near the ion's gyro-frequency. Observations of the ion cyclotron waves enable us to study the atmospheric loss due to solar wind pick-up process. At Mars, the exospheric hydrogen is picked up by the solar wind and produces proton cyclotron waves. The Mars Global Surveyor detected proton cyclotron waves which extend from the magnetosheath of Mars to over 12 Mars radii with amplitudes that vary slowly with distance. A hybrid simulation is applied to study the wave generation and evolution due to solar wind pick-up to try to understand the relation between the wave energy and pickup rate. By comparing the wave observations and the hybrid simulation results, we hope to better understand the hydrogen exosphere configuration and the loss of water from Mars.

  5. Pumping of helium and hydrogen by sputter-ion pumps. II. Hydrogen pumping

    SciTech Connect

    Welch, K.M.; Pate, D.J.; Todd, R.J. )

    1994-05-01

    The pumping of helium by various forms of sputter-ion pumps (i.e., SIPs) is given in part I [K. M. Welch, D. J. Pate, and R. J. Todd, J. Vac. Sci. Technol. A [bold 11], 1607 (1993)]. The pumping of hydrogen in diode and triode SIPs is herein discussed. The type of cathode material used in these pumps is shown to have a significant impact on the effectiveness with which hydrogen is pumped. Examples of this include data for pumps with aluminum, titanium, and titanium-alloy cathodes. Diode pumps with aluminum cathodes are shown to be no more effective in the pumping of hydrogen than in the pumping of helium. The use of titanium anodes and titanium [ital shielding] of a pump body is also shown to impact measurably the speed of a pump at very low pressures. This stems from the fact that hydrogen is [times]10[sup 6] more soluble in titanium than in stainless steel. Hydrogen becomes resident in the anodes because of fast neutral burial. Ions and fast neutrals of hydrogen are also buried in the walls of pump bodies. Outgassing of this hydrogen from the anodes and pump bodies results in a gradual increase in pump base pressure and consequential decrease in hydrogen pump speed at very low base pressures.

  6. Ion collector design for an energy recovery test proposal with the negative ion source NIO1

    NASA Astrophysics Data System (ADS)

    Variale, V.; Cavenago, M.; Agostinetti, P.; Sonato, P.; Zanotto, L.

    2016-02-01

    Commercial viability of thermonuclear fusion power plants depends also on minimizing the recirculation power used to operate the reactor. The neutral beam injector (NBI) remains one of the most important method for plasma heating and control. For the future fusion power plant project DEMO, a NBI wall plug efficiency at least of 0.45 is required, while efficiency of present NBI project is about 0.25. The D- beam from a negative ion source is partially neutralized by a gas cell, which leaves more than 40% of energy in residual beams (D- and D+), so that an ion beam energy recovery system can significantly contribute to optimize efficiency. Recently, the test negative ion source NIO1 (60 keV, 9 beamlets with 15 mA H- each) has been designed and built at RFX (Padua) for negative ion production efficiency and the beam quality optimization. In this paper, a study proposal to use the NIO1 source also for a beam energy recovery test experiment is presented and a preliminary design of a negative ion beam collector with simulations of beam energy recovery is discussed.

  7. Ion collector design for an energy recovery test proposal with the negative ion source NIO1.

    PubMed

    Variale, V; Cavenago, M; Agostinetti, P; Sonato, P; Zanotto, L

    2016-02-01

    Commercial viability of thermonuclear fusion power plants depends also on minimizing the recirculation power used to operate the reactor. The neutral beam injector (NBI) remains one of the most important method for plasma heating and control. For the future fusion power plant project DEMO, a NBI wall plug efficiency at least of 0.45 is required, while efficiency of present NBI project is about 0.25. The D(-) beam from a negative ion source is partially neutralized by a gas cell, which leaves more than 40% of energy in residual beams (D(-) and D(+)), so that an ion beam energy recovery system can significantly contribute to optimize efficiency. Recently, the test negative ion source NIO1 (60 keV, 9 beamlets with 15 mA H(-) each) has been designed and built at RFX (Padua) for negative ion production efficiency and the beam quality optimization. In this paper, a study proposal to use the NIO1 source also for a beam energy recovery test experiment is presented and a preliminary design of a negative ion beam collector with simulations of beam energy recovery is discussed. PMID:26932033

  8. Simulation of diatomic gas-wall interaction and accommodation coefficients for negative ion sources and accelerators.

    PubMed

    Sartori, E; Brescaccin, L; Serianni, G

    2016-02-01

    Particle-wall interactions determine in different ways the operating conditions of plasma sources, ion accelerators, and beams operating in vacuum. For instance, a contribution to gas heating is given by ion neutralization at walls; beam losses and stray particle production-detrimental for high current negative ion systems such as beam sources for fusion-are caused by collisional processes with residual gas, with the gas density profile that is determined by the scattering of neutral particles at the walls. This paper shows that Molecular Dynamics (MD) studies at the nano-scale can provide accommodation parameters for gas-wall interactions, such as the momentum accommodation coefficient and energy accommodation coefficient: in non-isothermal flows (such as the neutral gas in the accelerator, coming from the plasma source), these affect the gas density gradients and influence efficiency and losses in particular of negative ion accelerators. For ideal surfaces, the computation also provides the angular distribution of scattered particles. Classical MD method has been applied to the case of diatomic hydrogen molecules. Single collision events, against a frozen wall or a fully thermal lattice, have been simulated by using probe molecules. Different modelling approximations are compared.

  9. Simulation of diatomic gas-wall interaction and accommodation coefficients for negative ion sources and accelerators.

    PubMed

    Sartori, E; Brescaccin, L; Serianni, G

    2016-02-01

    Particle-wall interactions determine in different ways the operating conditions of plasma sources, ion accelerators, and beams operating in vacuum. For instance, a contribution to gas heating is given by ion neutralization at walls; beam losses and stray particle production-detrimental for high current negative ion systems such as beam sources for fusion-are caused by collisional processes with residual gas, with the gas density profile that is determined by the scattering of neutral particles at the walls. This paper shows that Molecular Dynamics (MD) studies at the nano-scale can provide accommodation parameters for gas-wall interactions, such as the momentum accommodation coefficient and energy accommodation coefficient: in non-isothermal flows (such as the neutral gas in the accelerator, coming from the plasma source), these affect the gas density gradients and influence efficiency and losses in particular of negative ion accelerators. For ideal surfaces, the computation also provides the angular distribution of scattered particles. Classical MD method has been applied to the case of diatomic hydrogen molecules. Single collision events, against a frozen wall or a fully thermal lattice, have been simulated by using probe molecules. Different modelling approximations are compared. PMID:26931910

  10. Interferences in photodetachment of a triatomic negative ion

    SciTech Connect

    Afaq, A.; Ahmad, M. A.; Rashid, A.; Ahmad, Iftikhar; Tahir, B. A.; Hussain, Muhammad Tahir

    2009-01-26

    The photodetachment of a triatomic negative ion is studied and the detached-electron wave function is obtained as a superposition of coherent waves originating from each atom of the system. The photodetached electron flux is evaluated on a screen placed at a large distance from the system, which displays strong interferences. A simple analytical formula is also obtained for the total photodetachment cross section. The formula approaches one time the cross sections for the one-center and two-center systems in the high photon energy limits. Also it approaches three times the cross section for one-center system in the low photon energy limits.

  11. Cesium control and diagnostics in surface plasma negative ion sources

    SciTech Connect

    Dudnikov, Vadim; Chapovsky, Pavel; Dudnikov, Andrei

    2010-02-15

    For efficient and reliable negative ion generation it is very important to improve a cesium control and diagnostics. Laser beam attenuation and resonance fluorescence can be used for measurement of cesium distribution and cesium control. Resonant laser excitation and two-photon excitation can be used for improved cesium ionization and cesium trapping in the discharge chamber. Simple and inexpensive diode lasers can be used for cesium diagnostics and control. Cesium migration along the surface is an important mechanism of cesium escaping. It is important to develop a suppression of cesium migration and cesium accumulation on the extraction system.

  12. Electron Rescattering in Above-Threshold Photodetachment of Negative Ions

    SciTech Connect

    Gazibegovic-Busuladzic, A.; Milosevic, D. B.; Becker, W.; Bergues, B.; Hultgren, H.; Kiyan, I. Yu.

    2010-03-12

    We present experimental and theoretical results on photodetachment of Br{sup -} and F{sup -} in a strong infrared laser field. The observed photoelectron spectra of Br{sup -} exhibit a high-energy plateau along the laser polarization direction, which is identified as being due to the rescattering effect. The shape and the extension of the plateau is found to be influenced by the depletion of negative ions during the interaction with the laser pulse. Our findings represent the first observation of electron rescattering in above-threshold photodetachment of an atomic system with a short-range potential.

  13. A Cartoon in One Dimension of the Hydrogen Molecular Ion

    ERIC Educational Resources Information Center

    Dutta, Sourav; Ganguly, Shreemoyee; Dutta-Roy, Binayak

    2008-01-01

    To illustrate the basic methodology involved in the quantum mechanics of molecules, a one-dimensional caricature of the hydrogen molecular ion (H[superscript +][subscript 2]) is presented, which is exactly solvable, in the Born-Oppenheimer approximation, in terms of elementary functions. The purpose of the exercise is to elucidate in a simple…

  14. A Sheath Model for Negative Ion Sources Including the Formation of a Virtual Cathode

    SciTech Connect

    McAdams, R.; King, D. B.; Surrey, E.

    2011-09-26

    A one dimensional model of the sheath between the plasma and the wall in a negative ion source has been developed. The plasma consists of positive ions, electrons and negative ions. The model takes into account the emission of negative ions from the wall into the sheath and thus represents the conditions in a caesiated ion source with surface production of negative ions. At high current densities of the emitted negative ions, the sheath is unable to support the transport of all the negative ions to the plasma and a virtual cathode is formed. This model takes this into account and allows the calculation of the transported negative ions across the sheath with the virtual cathode. The model has been extended to allow the linkage between plasma conditions at the sheath edge and the plasma to be made. Comparisons are made between the results of the model and experimental measurements.

  15. Ion-acoustic solitons in negative ion plasma with two-electron temperature distributions

    SciTech Connect

    Mishra, M. K.; Tiwari, R. S.; Chawla, J. K.

    2012-06-15

    Ion-acoustic solitons in a warm positive and negative ion species with different masses, concentrations, and charge states with two electron temperature distributions are studied. Using reductive perturbation method, Korteweg de-Vries (KdV) and modified-KdV (m-KdV) equations are derived for the system. The soliton solution of the KdV and m-KdV equations is discussed in detail. It is found that if the ions have finite temperatures, then there exist two types of modes, namely slow and fast ion-acoustic modes. It is also investigated that the parameter determining the nature of soliton (i.e., whether the system will support compressive or rarefactive solitons) is different for slow and fast modes. For the slow mode, the parameter is the relative temperature of the two ion species; whereas for the fast mode, it is the relative concentration of the two ion species. At a critical concentration of negative ions, both compressive and rarefactive solitons coexist. The amplitude and width of the solitons are discussed in detail at critical concentration for m-KdV solitons. The effect of the relative temperature of the two-electron and cold-electron concentration on the characteristics of the solitons are also discussed.

  16. First results of the ITER-relevant negative ion beam test facility ELISE (invited).

    PubMed

    Fantz, U; Franzen, P; Heinemann, B; Wünderlich, D

    2014-02-01

    An important step in the European R&D roadmap towards the neutral beam heating systems of ITER is the new test facility ELISE (Extraction from a Large Ion Source Experiment) for large-scale extraction from a half-size ITER RF source. The test facility was constructed in the last years at Max-Planck-Institut für Plasmaphysik Garching and is now operational. ELISE is gaining early experience of the performance and operation of large RF-driven negative hydrogen ion sources with plasma illumination of a source area of 1 × 0.9 m(2) and an extraction area of 0.1 m(2) using 640 apertures. First results in volume operation, i.e., without caesium seeding, are presented.

  17. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 1. Peptides to Proteins

    NASA Astrophysics Data System (ADS)

    Donohoe, Gregory C.; Khakinejad, Mahdiar; Valentine, Stephen J.

    2015-04-01

    Ion mobility spectrometry (IMS) coupled with hydrogen deuterium exchange (HDX)-mass spectrometry (MS) has been used to study the conformations of negatively-charged peptide and protein ions. Results are presented for ion conformers of angiotensin 1, a synthetic peptide (SP), bovine insulin, ubiquitin, and equine cytochrome c. In general, the SP ion conformers demonstrate a greater level of HDX efficiency as a greater proportion of the sites undergo HDX. Additionally, these ions exhibit the fastest rates of exchange. Comparatively, the angiotensin 1 ions exhibit a lower rate of exchange and HDX level presumably because of decreased accessibility of exchange sites by charge sites. The latter are likely confined to the peptide termini. Insulin ions show dramatically reduced HDX levels and exchange rates, which can be attributed to decreased conformational flexibility resulting from the disulfide bonds. For the larger ubiquitin and protein ions, increased HDX is observed for larger ions of higher charge state. For ubiquitin, a conformational transition from compact to more elongated species (from lower to higher charge states) is reflected by an increase in HDX levels. These results can be explained by a combination of interior site protection by compact conformers as well as decreased access by charge sites. The elongated cytochrome c ions provide the largest HDX levels where higher values correlate with charge state. These results are consistent with increased exchange site accessibility by additional charge sites. The data from these enhanced IMS-HDX experiments are described in terms of charge site location, conformer rigidity, and interior site protection.

  18. The charge spectrum of positive ions in a hydrogen aurora

    NASA Technical Reports Server (NTRS)

    Lynch, J.; Pulliam, D.; Leach, R.; Scherb, F.

    1976-01-01

    An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

  19. Electric field effects on resonance structures in negative ion photodetachment

    NASA Astrophysics Data System (ADS)

    Slonim, V. Z.; Greene, C. H.

    1991-12-01

    The photodetachment of negative ions in a static electric field exhibits some new characteristic features and has beer considered in various theortical approaches.1 Most of them, however, neglect the short-range interaction between the escaping electron and the atomic core, and must be modified to describe various resonant effects. Experiments2 have shown very rich resonant structure in a dc-field, which can be attributed to the mixing of different excited states in the negative ion, to competition between elastic and inelastic decay channels, and to tunneling effects induced by the field. It is known that various resonant structures in Photoprocesses can be successfully described within standard multichannel quantum defect theory (MQDT). We present a modified MQDT frame transformation approach to extend the standard method to long-range potentials with nonspherical symmetry. In our treatment both the electron-field and electron-atom interactions are treated nonperturbatively and on an equal footing. The resulting theoretical calculations are compared with experimental data on field-modified H? photodetachment in the vicinity of the n = 2 resonances.

  20. Observation of a shape resonance of the positronium negative ion

    PubMed Central

    Michishio, Koji; Kanai, Tsuneto; Kuma, Susumu; Azuma, Toshiyuki; Wada, Ken; Mochizuki, Izumi; Hyodo, Toshio; Yagishita, Akira; Nagashima, Yasuyuki

    2016-01-01

    When an electron binds to its anti-matter counterpart, the positron, it forms the exotic atom positronium (Ps). Ps can further bind to another electron to form the positronium negative ion, Ps− (e−e+e−). Since its constituents are solely point-like particles with the same mass, this system provides an excellent testing ground for the three-body problem in quantum mechanics. While theoretical works on its energy level and dynamics have been performed extensively, experimental investigations of its characteristics have been hampered by the weak ion yield and short annihilation lifetime. Here we report on the laser spectroscopy study of Ps−, using a source of efficiently produced ions, generated from the bombardment of slow positrons onto a Na-coated W surface. A strong shape resonance of 1Po symmetry has been observed near the Ps (n=2) formation threshold. The resonance energy and width measured are in good agreement with the result of three-body calculations. PMID:26983496

  1. Observation of a shape resonance of the positronium negative ion.

    PubMed

    Michishio, Koji; Kanai, Tsuneto; Kuma, Susumu; Azuma, Toshiyuki; Wada, Ken; Mochizuki, Izumi; Hyodo, Toshio; Yagishita, Akira; Nagashima, Yasuyuki

    2016-01-01

    When an electron binds to its anti-matter counterpart, the positron, it forms the exotic atom positronium (Ps). Ps can further bind to another electron to form the positronium negative ion, Ps(-) (e(-)e(+)e(-)). Since its constituents are solely point-like particles with the same mass, this system provides an excellent testing ground for the three-body problem in quantum mechanics. While theoretical works on its energy level and dynamics have been performed extensively, experimental investigations of its characteristics have been hampered by the weak ion yield and short annihilation lifetime. Here we report on the laser spectroscopy study of Ps(-), using a source of efficiently produced ions, generated from the bombardment of slow positrons onto a Na-coated W surface. A strong shape resonance of (1)P(o) symmetry has been observed near the Ps (n=2) formation threshold. The resonance energy and width measured are in good agreement with the result of three-body calculations. PMID:26983496

  2. RF-Plasma Source Commissioning in Indian Negative Ion Facility

    SciTech Connect

    Singh, M. J.; Bandyopadhyay, M.; Yadava, Ratnakar; Chakraborty, A. K.; Bansal, G.; Gahlaut, A.; Soni, J.; Kumar, Sunil; Pandya, K.; Parmar, K. G.; Sonara, J.; Kraus, W.; Heinemann, B.; Riedl, R.; Obermayer, S.; Martens, C.; Franzen, P.; Fantz, U.

    2011-09-26

    The Indian program of the RF based negative ion source has started off with the commissioning of ROBIN, the inductively coupled RF based negative ion source facility under establishment at Institute for Plasma research (IPR), India. The facility is being developed under a technology transfer agreement with IPP Garching. It consists of a single RF driver based beam source (BATMAN replica) coupled to a 100 kW, 1 MHz RF generator with a self excited oscillator, through a matching network, for plasma production and ion extraction and acceleration. The delivery of the RF generator and the RF plasma source without the accelerator, has enabled initiation of plasma production experiments. The recent experimental campaign has established the matching circuit parameters that result in plasma production with density in the range of 0.5-1x10{sup 18}/m{sup 3}, at operational gas pressures ranging between 0.4-1 Pa. Various configurations of the matching network have been experimented upon to obtain a stable operation of the set up for RF powers ranging between 25-85 kW and pulse lengths ranging between 4-20 s. It has been observed that the range of the parameters of the matching circuit, over which the frequency of the power supply is stable, is narrow and further experiments with increased number of turns in the coil are in the pipeline to see if the range can be widened. In this paper, the description of the experimental system and the commissioning data related to the optimisation of the various parameters of the matching network, to obtain stable plasma of required density, are presented and discussed.

  3. RF-Plasma Source Commissioning in Indian Negative Ion Facility

    NASA Astrophysics Data System (ADS)

    Singh, M. J.; Bandyopadhyay, M.; Bansal, G.; Gahlaut, A.; Soni, J.; Kumar, Sunil; Pandya, K.; Parmar, K. G.; Sonara, J.; Yadava, Ratnakar; Chakraborty, A. K.; Kraus, W.; Heinemann, B.; Riedl, R.; Obermayer, S.; Martens, C.; Franzen, P.; Fantz, U.

    2011-09-01

    The Indian program of the RF based negative ion source has started off with the commissioning of ROBIN, the inductively coupled RF based negative ion source facility under establishment at Institute for Plasma research (IPR), India. The facility is being developed under a technology transfer agreement with IPP Garching. It consists of a single RF driver based beam source (BATMAN replica) coupled to a 100 kW, 1 MHz RF generator with a self excited oscillator, through a matching network, for plasma production and ion extraction and acceleration. The delivery of the RF generator and the RF plasma source without the accelerator, has enabled initiation of plasma production experiments. The recent experimental campaign has established the matching circuit parameters that result in plasma production with density in the range of 0.5-1×1018/m3, at operational gas pressures ranging between 0.4-1 Pa. Various configurations of the matching network have been experimented upon to obtain a stable operation of the set up for RF powers ranging between 25-85 kW and pulse lengths ranging between 4-20 s. It has been observed that the range of the parameters of the matching circuit, over which the frequency of the power supply is stable, is narrow and further experiments with increased number of turns in the coil are in the pipeline to see if the range can be widened. In this paper, the description of the experimental system and the commissioning data related to the optimisation of the various parameters of the matching network, to obtain stable plasma of required density, are presented and discussed.

  4. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  5. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  6. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  7. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  8. Use of predissociation to enhance the atomic hydrogen ion fraction in ion sources

    DOEpatents

    Kim, Jinchoon

    1979-01-01

    A duopigatron ion source is modified by replacing the normal oxide-coated wire filament cathode of the ion source with a hot tungsten oven through which hydrogen gas is fed into the arc chamber. The hydrogen gas is predissociated in the hot oven prior to the arc discharge, and the recombination rate is minimized by hot walls inside of the arc chamber. With the use of the above modifications, the atomic H.sub.1.sup.+ ion fraction output can be increased from the normal 50% to greater than 70% with a corresponding decrease in the H.sub.2.sup.+ and H.sub.3.sup.+ molecular ion fraction outputs from the ion source.

  9. Hydrogen ions associated with the dry deposition of pollen

    SciTech Connect

    Noll, K.E.; Khalili, E.K. )

    1988-01-01

    The data provided in this paper demonstrates that pollen can generate significant amounts of hydrogen ions when added to water and that the deposition of tree pollen in forested areas represents a significant hydrogen ion source. Measurements of dry deposition of pollen were made during the months of May and June, 1987 in Northern Wisconsin, using a smooth surrogate surface. Rain samples were also collected. Deposited particles were weighed to determine mass fluxes, then washed and ion chromatographed for SO {sub 4} = and NO {sub 3} {minus} analysis. Species of pollen collected from different types of trees during the sampling period were analyzed for SO{sub 4} = NO {sub 3} and other trace constituents. The micrograms of hydrogen ions (protons) generated per gram for different types of pollen added to water, were measured. From 56 to 566 gm were generated per gram or pollen added. The amount generated varied with pollen type. Based on this information, the equivalent protons from the dry deposition of pollen were calculated and compared with the wet deposition proton data. The sulfate, nitrate, and protons associated with dry deposition were of a magnitude comparable with wet deposition.

  10. Method and apparatus for efficient photodetachment and purification of negative ion beams

    DOEpatents

    Beene, James R [Oak Ridge, TN; Liu, Yuan [Knoxville, TN; Havener, Charles C [Knoxville, TN

    2008-02-26

    Methods and apparatus are described for efficient photodetachment and purification of negative ion beams. A method of purifying an ion beam includes: inputting the ion beam into a gas-filled multipole ion guide, the ion beam including a plurality of ions; increasing a laser-ion interaction time by collisional cooling the plurality of ions using the gas-filled multipole ion guide, the plurality of ions including at least one contaminant; and suppressing the at least one contaminant by selectively removing the at least one contaminant from the ion beam by electron photodetaching at least a portion of the at least one contaminant using a laser beam.

  11. Simulating Negative Pickup Ions and Ion Cyclotron Wave Generation at Europa (Invited)

    NASA Astrophysics Data System (ADS)

    Desai, R. T.; Cowee, M.; Gary, S. P.; Wei, H.; Coates, A. J.; Kataria, D. O.; Fu, X.

    2015-12-01

    The mass loading of space environments through the ionisation of planetary atmospheres is a fundamental process governing the plasma interactions and long term evolution of celestial bodies across the solar system. Regions containing significant pickup ion populations have been observed to exhibit a rich variety of electromagnetic plasma wave phenomena, the characteristics and properties of which can be used to infer the ion species present, their spatial and temporal distributions, and the global ionisation rates of the neutral material. In this study we present hybrid (kinetic ion, massless fluid electron) simulations of ion pickup and Ion Cyclotron (IC) waves observed in the Jovian magnetosphere and draw comparisons to sub-alfvénic pickup observed by Cassini in the Saturnian system, and also to supra-alfvénic pickup at planetary bodies immersed directly in the solar wind. At Jupiter, Europa has been identified as the secondary mass loader in the magnetosphere, orbiting within a neutral gas torus at ~9.38 Rj. Near Europa, Galileo magnetometer observations displayed bursty IC wave characteristics at the gyrofrequency of a number of species including SO2, K, Cl, O2, and Na, suggesting a complex mass loading environment. A particular deduction from the dataset was the presence of both positively and negatively charged pickup ions, inferred from the left and right hand polarisations of the transverse waves. Using hybrid simulations for both positively and negatively charged Cl pickup ions we are able to self-consistently reproduce the growth of both right and left hand near-circularly polarised waves in agreement with linear theory and, using the observed wave amplitudes, estimate Cl pickup ion densities at Europa.

  12. Enhancement of pure volume negative ion production using a grid bias method or a magnetic filter method

    SciTech Connect

    Jyobira, Yasuhiro; Ito, Daisuke; Fukumasa, Osamu

    2008-02-15

    Volume production of hydrogen negative ion H{sup -} is studied in pure hydrogen plasmas using a grid bias method for plasma parameter control. The purposes of the present study are as follows. One is to investigate the possibility of controlling plasma parameters with a grid bias method in dc discharge plasmas; the other is to realize efficient negative ion production in H{sub 2} plasmas and to discuss the difference in plasma parameters control and H{sup -} production between the grid bias method and the usual magnetic filter method. The relationship between plasma parameters and extracted H{sup -} ion currents is discussed. It is confirmed that both high and low electron temperature T{sub e} plasmas are produced in the separated regions when the grid is negatively biased. The negative ion production depends strongly on the grid potential and related plasma conditions. Within certain plasma conditions, H{sup -} production with grid bias method is much higher than one with magnetic filter method.

  13. Displacement of the proton in hydrogen-bonded complexes of hydrogen fluoride by beryllium and magnesium ions

    SciTech Connect

    McDowell, Sean A. C.

    2009-05-14

    The displacement of the proton by a beryllium ion and by a magnesium ion from hydrogen-bonded complexes of hydrogen fluoride, of varying hydrogen bond strengths, was investigated theoretically using ab initio methods. Stable metal-containing species were obtained from all of the hydrogen-bonded complexes regardless of the strength of the hydrogen bond. It was found that the beryllium ion was energetically very effective in displacing the proton from hydrogen bonds, whereas the magnesium ion was unable to do so. The high stability of the beryllium-containing complexes is mainly due to the strong electrostatic bonding between the beryllium and fluoride atoms. This work supports the recent finding from a multidisciplinary bioinorganic study that beryllium displaces the proton in many strong hydrogen bonds.

  14. Enhanced surface production in H{sup -} ion sources by introducing a negatively biased secondary electrode

    SciTech Connect

    An, Young Hwa; Jung, Bong Ki; Hwang, Y. S.

    2010-02-15

    A transformer coupled plasma negative hydrogen ion source with an external rf antenna has been developed at SNU, which is capable of continuous operation with long lifetime. A positively biased plasma electrode (PE) has been successfully used for the optimization of H{sup -} extraction. With molybdenum-coated stainless steel PE, the enhancement of H{sup -} production at the electrode surface was observed at the bias voltage lower than the plasma potential. However, the low bias voltage is unfavorable to H{sup -} beam extraction since the negative ions are repelled. A second electrode is inserted in front of the PE to enhance H{sup -} production at the electrode surface without impeding beam extraction. By biasing the secondary electrode (SE) more negatively, H{sup -} production is clearly enhanced although the SE itself reduces H{sup -} beam currents because of suppressed electron transport in front of the PE. In this configuration enhancement of surface productions is most pronounced in tantalum electrode among various electrode materials.

  15. Multiple delivery cesium oven system for negative ion sources

    SciTech Connect

    Bansal, G.; Bhartiya, S.; Pandya, K.; Bandyopadhyay, M.; Singh, M. J.; Soni, J.; Gahlaut, A.; Parmar, K. G.; Chakraborty, A.

    2012-02-15

    Distribution of cesium in large negative ion beam sources to be operational in ITER, is presently based on the use of three or more cesium ovens, which operate simultaneously and are controlled remotely. However, use of multiple Cs ovens simultaneously is likely to pose difficulties in operation and maintenance of the ovens. An alternate method of Cs delivery, based on a single oven distribution system is proposed as one which could reduce the need of simultaneous operation of many ovens. A proof of principle experiment verifying the concept of a multinozzle distributor based Cs oven has been carried out at Institute for Plasma Research. It is also observed that the Cs flux is not controlled by Cs reservoir temperature after few hours of operation but by the temperature of the distributor which starts behaving as a Cs reservoir.

  16. High-Resolution Laser Spectroscopy on the Negative Osmium Ion

    SciTech Connect

    Warring, U.; Amoretti, M.; Canali, C.; Fischer, A.; Heyne, R.; Meier, J. O.; Morhard, Ch.; Kellerbauer, A.

    2009-01-30

    We have applied a combination of laser excitation and electric-field detachment to negative atomic ions for the first time, resulting in an enhancement of the excited-state detection efficiency for spectroscopy by at least 2 orders of magnitude. Applying the new method, a measurement of the bound-bound electric-dipole transition frequency in {sup 192}Os{sup -} was performed using collinear spectroscopy with a narrow-bandwidth cw laser. The transition frequency was found to be 257.831 190(35) THz [wavelength 1162.747 06(16) nm, wave number 8600.3227(12) cm{sup -1}], in agreement with the only prior measurement, but with more than 100-fold higher precision.

  17. Improvement of uniformity of the negative ion beams by tent-shaped magnetic field in the JT-60 negative ion source

    SciTech Connect

    Yoshida, Masafumi Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; Ohzeki, Masahiro; Seki, Norikazu; Sasaki, Shunichi; Shimizu, Tatsuo; Terunuma, Yuto; Grisham, Larry R.

    2014-02-15

    Non-uniformity of the negative ion beams in the JT-60 negative ion source with the world-largest ion extraction area was improved by modifying the magnetic filter in the source from the plasma grid (PG) filter to a tent-shaped filter. The magnetic design via electron trajectory calculation showed that the tent-shaped filter was expected to suppress the localization of the primary electrons emitted from the filaments and created uniform plasma with positive ions and atoms of the parent particles for the negative ions. By modifying the magnetic filter to the tent-shaped filter, the uniformity defined as the deviation from the averaged beam intensity was reduced from 14% of the PG filter to ∼10% without a reduction of the negative ion production.

  18. The Negative Mode Proteome with Activated Ion Negative Electron Transfer Dissociation (AI-NETD)*

    PubMed Central

    Riley, Nicholas M.; Rush, Matthew J. P.; Rose, Christopher M.; Richards, Alicia L.; Kwiecien, Nicholas W.; Bailey, Derek J.; Hebert, Alexander S.; Westphall, Michael S.; Coon, Joshua J.

    2015-01-01

    The field of proteomics almost uniformly relies on peptide cation analysis, leading to an underrepresentation of acidic portions of proteomes, including relevant acidic posttranslational modifications. Despite the many benefits negative mode proteomics can offer, peptide anion analysis remains in its infancy due mainly to challenges with high-pH reversed-phase separations and a lack of robust fragmentation methods suitable for peptide anion characterization. Here, we report the first implementation of activated ion negative electron transfer dissociation (AI-NETD) on the chromatographic timescale, generating 7,601 unique peptide identifications from Saccharomyces cerevisiae in single-shot nLC-MS/MS analyses of tryptic peptides—a greater than 5-fold increase over previous results with NETD alone. These improvements translate to identification of 1,106 proteins, making this work the first negative mode study to identify more than 1,000 proteins in any system. We then compare the performance of AI-NETD for analysis of peptides generated by five proteases (trypsin, LysC, GluC, chymotrypsin, and AspN) for negative mode analyses, identifying as many as 5,356 peptides (1,045 proteins) with LysC and 4,213 peptides (857 proteins) with GluC in yeast—characterizing 1,359 proteins in total. Finally, we present the first deep-sequencing approach for negative mode proteomics, leveraging offline low-pH reversed-phase fractionation prior to online high-pH separations and peptide fragmentation with AI-NETD. With this platform, we identified 3,467 proteins in yeast with trypsin alone and characterized a total of 3,730 proteins using multiple proteases, or nearly 83% of the expressed yeast proteome. This work represents the most extensive negative mode proteomics study to date, establishing AI-NETD as a robust tool for large-scale peptide anion characterization and making the negative mode approach a more viable platform for future proteomic studies. PMID:26193884

  19. Independent-particle models for light negative atomic ions

    NASA Technical Reports Server (NTRS)

    Ganas, P. S.; Talman, J. D.; Green, A. E. S.

    1980-01-01

    For the purposes of astrophysical, aeronomical, and laboratory application, a precise independent-particle model for electrons in negative atomic ions of the second and third period is discussed. The optimum-potential model (OPM) of Talman et al. (1979) is first used to generate numerical potentials for eight of these ions. Results for total energies and electron affinities are found to be very close to Hartree-Fock solutions. However, the OPM and HF electron affinities both depart significantly from experimental affinities. For this reason, two analytic potentials are developed whose inner energy levels are very close to the OPM and HF levels but whose last electron eigenvalues are adjusted precisely with the magnitudes of experimental affinities. These models are: (1) a four-parameter analytic characterization of the OPM potential and (2) a two-parameter potential model of the Green, Sellin, Zachor type. The system O(-) or e-O, which is important in upper atmospheric physics is examined in some detail.

  20. Hydrogen recycling control by helium ion bombardment onto carbonized surfaces

    NASA Astrophysics Data System (ADS)

    Sugai, H.; Toyoda, H.; Ohshita, S.; Yoshida, S.; Sagara, A.

    1989-04-01

    A strong pumping effect was observed in a hydrogen recycling simulation experiment in a carbonized toroidal device at room temperature. The pumping effect was induced by conditioning the carbon-thin-film deposited wall with a short (~10 min) helium glow discharge. A large amount of hydrogen (~10 16cm-2) was desorbed from carbon films with helium ion bombardment at 200 eV. After conditioning, the recycling coefficient was drastically reduced from about 2 to a value close to zero. Furthermore, an advanced (multilayer) coating was developed with use of helium ion induced desorption, where a short burst of methane was admixed at regular intervals in a helium glow discharge. A fairly large wall pumping was realized by the multilayer coating when the thickness of each layer and the helium bombarding time were optimized.

  1. Negative thermal ion mass spectrometry of oxygen in phosphates

    NASA Astrophysics Data System (ADS)

    Holmden, C.; Papanastassiou, D. A.; Wasserburg, G. J.

    1997-06-01

    A novel technique for the precise measurement of oxygen isotopes by negative thermal ion mass spectrometry (NTIMS) is presented. The technique is ideally suited to the analysis of oxygen isotopes in phosphates which form intense P03 ion beams. Since P is monoisotopic, the mass spectrum for P0 3- at 79, 80, and 81 corresponds to 1660, 170, and 180. Natural and synthetic phosphates are converted and loaded on the mass spectrometer filament as Ag 3PO 4 precipitated directly from ammoniacal solution. To lower the work function of the filament, BaCl, is added in a 1:1 molar ratio of PO 4:Ba. Using these procedures, Br - mass interference (at 79 and 81 amu) is eliminated for typical analyses. Experiments with 180-enriched water show less than 1 % O-exchange between sample PO 4 and adsorbed water, and there is no O-exchange with trace OZ present in the mass spectrometer source chamber. The ionization efficiency of PO 4, as P0 3- is >10% compared to 0.01% for both conventional dual inlet Gas Isotope Ratio Mass Spectrometry (GIRMS) and secondary ion mass spectrometry (SIMS). Therefore, NTIMS offers exceptional sensitivity enabling routine and precise oxygen isotope analysis of sub-microgram samples of PO 4, (<21 nmoles equivalent CO 2 gas) without need for lengthy chemical pre-treatment reproducibility of the sample. Overall external precision is ±1%c (2σ) for 18O/16 O and 170/15O with of instrumental isotope fractionation (calculated from 18O/16O of ±0.5%c amu -1. Small phosphate samples including single mineral grains from meteorites, or apatite microfossils, can be analyzed by this technique.

  2. Simulation Based on Negative ion pair Techniques of Electric propulsion In Satellite Mission Using Chlorine Gas

    NASA Astrophysics Data System (ADS)

    Bakkiyaraj, R.

    R.Bakkiyaraj,Assistant professor,Government college of Engineering ,Bargur,Tamilnadu. *C.Sathiyavel, PG Student and Department of Aeronautical Engineering/Branch of Avionics, PSN college of Engineering and Technology,Tirunelveli,India. Abstract: Ion propulsion rocket system is expected to become popular with the development of ion-ion pair techniques because of their stimulated of low propellant, Design of repulsive between negative ions with low electric power and high efficiency. A Negative ion pair of ion propulsion rocket system is proposed in this work .Negative Ion Based Rocket system consists of three parts 1.ionization chamber 2. Repulsion force and ion accelerator 3. Exhaust of Nozzle. The Negative ions from electro negatively gas are produced by attachment of the gas ,such as chlorine with electron emitted from a Electron gun ionization chamber. The formulate of large stable negative ion is achievable in chlorine gas with respect to electron affinity (∆E). When a neutral chlorine atom in the gaseous form picks up an electron to form a cl- ion, it releases energy of 349 kJ/mol or 3.6 eV/atom. It is said to have an electron affinity of -349 kJ/mol ,the negative sign indicating that energy is released during this process .The distance between negative ions pair is important for the evaluation of the rocket thrust and is also determined by the exhaust velocity of the propellant. The mass flow rate of ions is related to the ion beam current. Accelerate the Negative ions to a high velocity in the thrust vector direction with a significantly intense grids and the exhaust of negative ions through Nozzle. The simulation of the ion propulsion system has been carried out by MATLAB. By comparing the simulation results with the theoretical and previous results, we have found that the proposed method is achieved of thrust value with low electric power for simulating the ion propulsion rocket system

  3. Ion Pairs or Neutral Molecule Adducts? Cooperativity in Hydrogen Bonding

    ERIC Educational Resources Information Center

    DeKock, Roger L.; Schipper, Laura A.; Dykhouse, Stephanie C.; Heeringa, Lee P.; Brandsen, Benjamin M.

    2009-01-01

    We performed theoretical studies on the systems NH[subscript 3] times HF times mH[subscript 2]O, NH[subscript 3] times HCl times mH[subscript 2]O, with m = 0, 1, 2, and 6. The molecules with m = 0 form hydrogen-bonded adducts with little tendency to form an ion-pair structure. The molecule NH[subscript 3] times HCl times H[subscript 2]O cannot be…

  4. Microsecond pulsed hydrogen/deuterium exchange of electrosprayed ubiquitin ions stored in a linear ion trap.

    PubMed

    Rajabi, Khadijeh

    2015-02-01

    A pulse of D2O vapour on the order of microseconds is allowed to react with the +6 to +9 charge states of ubiquitin confined in a linear ion trap (LIT). Two envelopes of peaks are detected for the ions of ubiquitin, corresponding to the ions that exchange more quickly and more slowly. The deuterium uptake of the protonated sites on ubiquitin ions accounts for the ion population with the fast exchange. The hydrogen/deuterium exchange (HDX) kinetics of ubiquitin ions trapped in the LIT for 200 ms showed comparable structural transitions to those trapped for 300 ms. When ions are trapped for longer, i.e. up to 2000 ms, mainly the slow exchanging ion population is detected. In all experiments the +7 ions exchange the most, suggesting a short distance between the surface protonated sites and nearby charged sites, and concomitantly high accessibility of surface protonated sites towards D2O. The +6 ions are more compact than the +7 ions but have one fewer protonated site, therefore fewer surface availabilities for D2O attack. The data suggest that the +6 ions keep most of their solution-phase contacts intact while the hydrophobic core is slightly interrupted in the +7 ions, possibly due to the exposure of charged His68 that is normally buried in the hydrophobic pocket. The +8 and +9 ions have more protonated sites but are less compact than the +7 ions because of Coulombic repulsion, resulting in a larger distance between the protonated sites and the basic sites. The data indicate that the HDX mechanism of ions with the slower exchange corresponding to the second envelope of peaks is primarily governed via a relay mechanism. The results suggest that the pulsed HDX MS method is sampling a population of ubiquitin ions with a similar backbone fold to the solution.

  5. Microsecond pulsed hydrogen/deuterium exchange of electrosprayed ubiquitin ions stored in a linear ion trap.

    PubMed

    Rajabi, Khadijeh

    2015-02-01

    A pulse of D2O vapour on the order of microseconds is allowed to react with the +6 to +9 charge states of ubiquitin confined in a linear ion trap (LIT). Two envelopes of peaks are detected for the ions of ubiquitin, corresponding to the ions that exchange more quickly and more slowly. The deuterium uptake of the protonated sites on ubiquitin ions accounts for the ion population with the fast exchange. The hydrogen/deuterium exchange (HDX) kinetics of ubiquitin ions trapped in the LIT for 200 ms showed comparable structural transitions to those trapped for 300 ms. When ions are trapped for longer, i.e. up to 2000 ms, mainly the slow exchanging ion population is detected. In all experiments the +7 ions exchange the most, suggesting a short distance between the surface protonated sites and nearby charged sites, and concomitantly high accessibility of surface protonated sites towards D2O. The +6 ions are more compact than the +7 ions but have one fewer protonated site, therefore fewer surface availabilities for D2O attack. The data suggest that the +6 ions keep most of their solution-phase contacts intact while the hydrophobic core is slightly interrupted in the +7 ions, possibly due to the exposure of charged His68 that is normally buried in the hydrophobic pocket. The +8 and +9 ions have more protonated sites but are less compact than the +7 ions because of Coulombic repulsion, resulting in a larger distance between the protonated sites and the basic sites. The data indicate that the HDX mechanism of ions with the slower exchange corresponding to the second envelope of peaks is primarily governed via a relay mechanism. The results suggest that the pulsed HDX MS method is sampling a population of ubiquitin ions with a similar backbone fold to the solution. PMID:25553956

  6. Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

    SciTech Connect

    Lishev, S.; Schiesko, L.; Wünderlich, D.; Fantz, U.

    2015-04-08

    A numerical model, based on the fluid plasma theory, has been used for description of the spatial distribution of the plasma parameters (electron density and temperature, plasma potential as well as densities of the three types of positive hydrogen ions) in the IPP prototype RF negative hydrogen ion source. The model covers the driver and the expansion plasma region of the source with their actual size and accounts for the presence of the magnetic filter field with its actual value and location as well as for the bias potential applied to the plasma grid. The obtained results show that without a magnetic filter the two 2D geometries considered, respectively, with an axial symmetry and a planar one, represent accurately the complex 3D structure of the source. The 2D model with a planar symmetry (where the E×B and diamagnetic drifts could be involved in the description) has been used for analysis of the influence, via the charged-particle and electron-energy fluxes, of the magnetic filter and of the bias potential on the spatial structure of the plasma parameters in the source. Benchmarking of results from the code to experimental data shows that the model reproduces the general trend in the axial behavior of the plasma parameters in the source.

  7. Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

    NASA Astrophysics Data System (ADS)

    Lishev, S.; Schiesko, L.; Wünderlich, D.; Fantz, U.

    2015-04-01

    A numerical model, based on the fluid plasma theory, has been used for description of the spatial distribution of the plasma parameters (electron density and temperature, plasma potential as well as densities of the three types of positive hydrogen ions) in the IPP prototype RF negative hydrogen ion source. The model covers the driver and the expansion plasma region of the source with their actual size and accounts for the presence of the magnetic filter field with its actual value and location as well as for the bias potential applied to the plasma grid. The obtained results show that without a magnetic filter the two 2D geometries considered, respectively, with an axial symmetry and a planar one, represent accurately the complex 3D structure of the source. The 2D model with a planar symmetry (where the E×B and diamagnetic drifts could be involved in the description) has been used for analysis of the influence, via the charged-particle and electron-energy fluxes, of the magnetic filter and of the bias potential on the spatial structure of the plasma parameters in the source. Benchmarking of results from the code to experimental data shows that the model reproduces the general trend in the axial behavior of the plasma parameters in the source.

  8. Nickel-Hydrogen and Lithium Ion Space Batteries

    NASA Technical Reports Server (NTRS)

    Reid, Robert O., II

    2004-01-01

    The tasks of the Electrochemistry Branch of NASA Glenn Research Center are to improve and develop high energy density and rechargeable, life-long batteries. It is with these batteries that people across the globe are able to power their cell phones, laptop computers, and cameras. Here, at NASA Glenn Research Center, the engineers and scientists of the Electrochemistry branch are leading the way in the development of more powerful, long life batteries that can be used to power space shuttles and satellites. As of now, the cutting edge research and development is being done on nickel-hydrogen batteries and lithium ion batteries. Presently, nickel-hydrogen batteries are common types of batteries that are used to power satellites, space stations, and space shuttles, while lithium batteries are mainly used to power smaller appliances such as portable computers and phones. However, the Electrochemistry Branch at NASA Glenn Research Center is focusing more on the development of lithium ion batteries for deep space use. Because of the limitless possibilities, lithium ion batteries can revolutionize the space industry for the better. When compared to nickel-hydrogen batteries, lithium ion batteries possess more advantages than its counterpart. Lithium ion batteries are much smaller than nickel-hydrogen batteries and also put out more power. They are more energy efficient and operate with much more power at a reduced weight than its counterpart. Lithium ion cells are also cheaper to make, possess flexibility that allow for different design modifications. With those statistics in hand, the Electrochemistry Branch of NASA Glenn has decided to shut down its Nickel-Hydrogen testing for lithium ion battery development. Also, the blackout in the summer of 2003 eliminated vital test data, which played a part in shutting down the program. from the nickel-hydrogen batteries and compare it to past data. My other responsibilities include superheating the electrolyte that is used in the

  9. Improving Negative Ion Beam Quality and Purity with a RF Quadrupole Cooler

    SciTech Connect

    Liu, Y.

    2011-09-26

    Recent progress in the development of a gas-filled RF quadrupole ion cooler for cooling negative ions is reported. Experiments demonstrate that negative ion beams can be cooled to 2 eV FWHM energy spread with more than 50% transmission through the cooler. The RFQ cooler can potentially improve the purity of radioactive ion beams by magnetic mass separation. New developments on purifying negative ion beams by photodetachment in the RFQ cooler are presented. With a laser of proper photon energy, nearly 100% suppression of the unwanted negative ions in the RFQ cooler has been observed, while the desired ions remain mostly intact. A recent experimental study demonstrates that pure ground state negative ion beams can be obtained by state-selective photodetachment in the RFQ cooler.

  10. Improving Negative Ion Beam Quality And Purity With A RF Quadrupole Cooler

    SciTech Connect

    Liu, Yuan

    2011-01-01

    Recent progress in the development of a gas-filled RF quadrupole ion cooler for cooling negative ions is reported. Experiments demonstrate that negative ion beams can be cooled to 2 eV FWHM energy spread with more than 50% transmission through the cooler. The RFQ cooler can potentially improve the purity of radioactive ion beams by magnetic mass separation. New developments on purifying negative ion beams by photodetachment in the RFQ cooler are presented. With a laser of proper photon energy, nearly 100% suppression of the unwanted negative ions in the RFQ cooler has been observed, while the desired ions remain mostly intact. A recent experimental study demonstrates that pure ground state negation ion beams can be obtained by state-selective photodetachment in the RFQ cooler.

  11. Estimation of negative ions in VHF SiH4/H2 plasma

    NASA Astrophysics Data System (ADS)

    Yamane, Tsukasa; Nakano, Shinya; Nakao, Sachiko; Takeuchi, Yoshiaki; Ichiki, Ryuta; Muta, Hiroshi; Uchino, Kiichiro; Kawai, Yoshinobu

    2014-11-01

    The characteristics of a VHF SiH4/H2 plasma (frequency: 60 MHz) at high pressures were examined as a function of silane concentration with a heated Langmuir probe. Anomalous reductions in electron saturation current were observed, suggesting the existence of many negative ions. An estimation of the concentration of negative ions was attempted using the sheath theory including negative ions. It was found that there exist H- and SiH3- ions as dominant negative ions in the VHF SiH4/H2 plasma. In addition, the measured floating potential agreed with the theoretical value.

  12. Reflection properties of hydrogen ions at helium irradiated tungsten surfaces

    NASA Astrophysics Data System (ADS)

    Doi, K.; Tawada, Y.; Lee, H. T.; Kato, S.; Tanaka, N.; Sasao, M.; Kisaki, M.; Nishiura, M.; Matsumoto, Y.; Kenmotsu, T.; Wada, M.; Ueda, Y.; Yamaoka, H.

    2016-02-01

    Nanostructured W surfaces prepared by He bombardment exhibit characteristic angular distributions of hydrogen ion reflection upon injection of 1 keV H+ beam. A magnetic momentum analyzer that can move in the vacuum chamber has measured the angular dependence of the intensity and the energy of reflected ions. Broader angular distributions were observed for He-irradiated tungsten samples compared with that of the intrinsic polycrystalline W. Both intensity and energy of reflected ions decreased in the following order: the polycrystalline W, the He-bubble containing W, and the fuzz W. Classical trajectory Monte Carlo simulations based on Atomic Collision in Amorphous Target code suggests that lower atom density near the surface can make the reflection coefficients lower due to increasing number of collisions.

  13. The Behavior of Ion-Implanted Hydrogen in Gallium Nitride

    SciTech Connect

    Myers, S.M.; Headley, T.J.; Hills, C.R.; Han, J.; Petersen, G.A.; Seager, C.H.; Wampler, W.R.

    1999-01-07

    Hydrogen was ion-implanted into wurtzite-phase GaN, and its transport, bound states, and microstructural effects during annealing up to 980 C were investigated by nuclear-reaction profiling, ion-channeling analysis, transmission electron microscopy, and infrared (IR) vibrational spectroscopy. At implanted concentrations 1 at.%, faceted H{sub 2} bubbles formed, enabling identification of energetically preferred surfaces, examination of passivating N-H states on these surfaces, and determination of the diffusivity-solubility product of the H. Additionally, the formation and evolution of point and extended defects arising from implantation and bubble formation were characterized. At implanted H concentrations 0.1 at.%, bubble formation was not observed, and ion-channeling analysis indicated a defect-related H site located within the [0001] channel.

  14. Effect of high energy electrons on H⁻ production and destruction in a high current DC negative ion source for cyclotron.

    PubMed

    Onai, M; Etoh, H; Aoki, Y; Shibata, T; Mattei, S; Fujita, S; Hatayama, A; Lettry, J

    2016-02-01

    Recently, a filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In this study, numerical modeling of the filament arc-discharge source plasma has been done with kinetic modeling of electrons in the ion source plasmas by the multi-cusp arc-discharge code and zero dimensional rate equations for hydrogen molecules and negative ions. In this paper, main focus is placed on the effects of the arc-discharge power on the electron energy distribution function and the resultant H(-) production. The modelling results reasonably explains the dependence of the H(-) extraction current on the arc-discharge power in the experiments. PMID:26932009

  15. Recent Progress in the Negative-Ion-Based Neutral Beam Injectors in Large Helical Device

    SciTech Connect

    Takeiri, Y.; Tsumori, K.; Ikeda, K.; Osakabe, M.; Nagaoka, K.; Oka, Y.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Kaneko, O.

    2009-03-12

    Negative-ion-based neutral beam injection (negative-NBI) system has been operated for 10 years in Large Helical Device (LHD). The injection power has been increased year by year, according to the improvement of the negative ion sources. Up to now, every injector achieves the designed injection energy and power of 180 keV-5 MW with hydrogen beams, and the total injection power exceeds 16 MW with three injectors. In the multi-round aperture grounded grid (GG), the diameter of a round aperture has been enlarged for higher GG transparency. Then, the GG heat load is reduced, as well as in the multi-slotted GG, and the voltage holding ability in the beam acceleration was improved. As a result, the beam energy is raised and the injection power is increased. To improve the anisotropic property of the beamlet convergence condition between the perpendicular and the parallel directions to the slots in the multi-slotted GG, a round-shape aperture of the steering grid (SG) has been changed to a racetrack shape. As a result, the difference of the beamlet conversion condition is much mitigated, and the injection efficiency (port-transmission efficiency) is improved, leading to 188 keV-6.4 MW injection. The Cs consumption is observed to be proportional to the tungsten evaporation from filaments. The Cs behavior is investigated with optical emission spectroscopy. During the beam extraction, the Cs recycling is dominated by Cs on the backplate, which is evaporated into the plasma by the backstreaming positive ions, and the wall surfaces should be loss regions for the supplied Cs.

  16. Ion-molecule reactions and vibrational deactivation of H2/+/ ions in mixtures of hydrogen and helium

    NASA Technical Reports Server (NTRS)

    Theard, L. P.; Huntress, W. T., Jr.

    1974-01-01

    Use of ion cyclotron resonance methods to measure the thermal energy rate constants for a number of ion-molecule reactions involving hydrogen and hydrogen-helium mixtures. Assuming that the distribution of initial vibrational states in the H2(+) ion is a near-Franck-Condon distribution, the occurrence of collisional deactivation of vibrationally excited H2(+) ions by He atoms is identified, and an approximate rate constant for the deactivation process and its dependence on vibrational energy are given.

  17. Rovibrational molecular populations, atoms, and negative ions in H2 and D2 magnetic multicusp discharges

    NASA Astrophysics Data System (ADS)

    Pealat, M.; Taran, J.-P. E.; Bacal, M.; Hillion, F.

    1985-06-01

    Coherent anti-Stokes Raman scattering is applied to the study of rovibrational populations in magnetic multicusp H2 and D2 discharges. This subject is of interest to negative hydrogen-ion formation by volume plasma processes. The populations of high-lying rotational states (J greater than 5) in the vibrational levels v = 0, 1, and 2 are found to be significantly higher than expected from the Boltzmann law. In H2 the net populations of the first four vibrational levels follow approximately the Boltzmann law, with the vibrational temperature of 2390 K (in a 90 V-10 A discharge at 55 micro bar). In similar discharge conditions, the population of the state v = 3 in D2 is higher than expected from the Boltzmann law. In the presence of the discharge a deficiency in H2 and D2 molecule density was observed and was attributed to the possible presence of H and D atoms. This was verified by an independent measurement of the atomic fraction and temperature. The density of negative ions, measured by the photodetachment technique, is also reported.

  18. Arc plasma generator of atomic driver for steady-state negative ion source

    NASA Astrophysics Data System (ADS)

    Ivanov, A. A.; Belchenko, Yu. I.; Davydenko, V. I.; Ivanov, I. A.; Kolmogorov, V. V.; Listopad, A. A.; Mishagin, V. V.; Putvinsky, S. V.; Shulzhenko, G. I.; Smirnov, A.

    2014-02-01

    The paper reviews the results of development of steady-state arc-discharge plasma generator with directly heated LaB6 cathode. This arc-discharge plasma generator produces a plasma jet which is to be converted into an atomic one after recombination on a metallic plate. The plate is electrically biased relative to the plasma in order to control the atom energies. Such an intensive jet of hydrogen atoms can be used in negative ion sources for effective production of negative ions on a cesiated surface of plasma grid. All elements of the plasma generator have an augmented water cooling to operate in long pulse mode or in steady state. The thermo-mechanical stresses and deformations of the most critical elements of the plasma generator were determined by simulations. Magnetic field inside the discharge chamber was optimized to reduce the local power loads. The first tests of the steady-state arc plasma generator prototype have performed in long-pulse mode.

  19. Arc plasma generator of atomic driver for steady-state negative ion source

    SciTech Connect

    Ivanov, A. A.; Belchenko, Yu. I.; Davydenko, V. I.; Ivanov, I. A.; Kolmogorov, V. V.; Listopad, A. A. Mishagin, V. V.; Shulzhenko, G. I.; Putvinsky, S. V.; Smirnov, A.

    2014-02-15

    The paper reviews the results of development of steady-state arc-discharge plasma generator with directly heated LaB{sub 6} cathode. This arc-discharge plasma generator produces a plasma jet which is to be converted into an atomic one after recombination on a metallic plate. The plate is electrically biased relative to the plasma in order to control the atom energies. Such an intensive jet of hydrogen atoms can be used in negative ion sources for effective production of negative ions on a cesiated surface of plasma grid. All elements of the plasma generator have an augmented water cooling to operate in long pulse mode or in steady state. The thermo-mechanical stresses and deformations of the most critical elements of the plasma generator were determined by simulations. Magnetic field inside the discharge chamber was optimized to reduce the local power loads. The first tests of the steady-state arc plasma generator prototype have performed in long-pulse mode.

  20. Arc plasma generator of atomic driver for steady-state negative ion source.

    PubMed

    Ivanov, A A; Belchenko, Yu I; Davydenko, V I; Ivanov, I A; Kolmogorov, V V; Listopad, A A; Mishagin, V V; Putvinsky, S V; Shulzhenko, G I; Smirnov, A

    2014-02-01

    The paper reviews the results of development of steady-state arc-discharge plasma generator with directly heated LaB6 cathode. This arc-discharge plasma generator produces a plasma jet which is to be converted into an atomic one after recombination on a metallic plate. The plate is electrically biased relative to the plasma in order to control the atom energies. Such an intensive jet of hydrogen atoms can be used in negative ion sources for effective production of negative ions on a cesiated surface of plasma grid. All elements of the plasma generator have an augmented water cooling to operate in long pulse mode or in steady state. The thermo-mechanical stresses and deformations of the most critical elements of the plasma generator were determined by simulations. Magnetic field inside the discharge chamber was optimized to reduce the local power loads. The first tests of the steady-state arc plasma generator prototype have performed in long-pulse mode.

  1. Ways to improve the efficiency and reliability of radio frequency driven negative ion sources for fusion

    SciTech Connect

    Kraus, W.; Briefi, S.; Fantz, U.; Gutmann, P.; Doerfler, J.

    2014-02-15

    Large RF driven negative hydrogen ion sources are being developed at IPP Garching for the future neutral beam injection system of ITER. The overall power efficiency of these sources is low, because for the RF power supply self-excited generators are utilized and the plasma is generated in small cylindrical sources (“drivers”) and expands into the source main volume. At IPP experiments to reduce the primary power and the RF power required for the plasma production are performed in two ways: The oscillator generator of the prototype source has been replaced by a transistorized RF transmitter and two alternative driver concepts, a spiral coil, in which the field is concentrated by ferrites, which omits the losses by plasma expansion and a helicon source are being tested.

  2. Experiments on a reflex-type sheet plasma negative-ion source

    SciTech Connect

    Ando, A.; Kuroda, T.; Oka, Y.; Kaneko, O.; Karita, A.; Kawamoto, T. )

    1990-01-01

    Negative hydrogen ions are extracted from a reflex-type sheet plasma. Electron density and temperature profiles are measured with changing the filling gas pressure, and they are optimized to the H{sup {minus}} production at the optimum gas pressure. The optimum gas pressure is 5 mTorr for the discharge current {ital I}{sub {ital d}} =2 A. As the discharge current {ital I}{sub {ital d}} increases, H{sup {minus}} current increases linearly corresponding to the density increase in the center region, but saturates above {ital I}{sub {ital d}} =40 A. The maximum extracted H{sup {minus}} current density of 4 mA/cm{sup 2} is obtained at {ital I}{sub {ital d}}=100 A.

  3. Electron detachment from negative ions in a short laser pulse

    NASA Astrophysics Data System (ADS)

    Shearer, S. F. C.; Smyth, M. C.; Gribakin, G. F.

    2011-09-01

    We present an efficient and accurate method to study electron detachment from negative ions by a few-cycle linearly polarized laser pulse. The adiabatic saddle-point method of Gribakin and Kuchiev [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.55.3760 55, 3760 (1997)] is adapted to calculate the transition amplitude for a short laser pulse. Its application to a pulse with N optical cycles produces 2(N+1) saddle points in complex time, which form a characteristic “smile.” Numerical calculations are performed for H- in a 5-cycle pulse with frequency 0.0043 a.u. and intensities of 1010, 5×1010, and 1011 W/cm2, and for various carrier-envelope phases. We determine the spectrum of the photoelectrons as a function of both energy and emission angle, as well as the angle-integrated energy spectra and total detachment probabilities. Our calculations show that the dominant contribution to the transition amplitude is given by 5-6 central saddle points, which correspond to the strongest part of the pulse. We examine the dependence of the photoelectron angular distributions on the carrier-envelope phase and show that measuring such distributions can provide a way of determining this phase.

  4. Electron detachment from negative ions in a short laser pulse

    SciTech Connect

    Shearer, S. F. C.; Smyth, M. C.; Gribakin, G. F.

    2011-09-15

    We present an efficient and accurate method to study electron detachment from negative ions by a few-cycle linearly polarized laser pulse. The adiabatic saddle-point method of Gribakin and Kuchiev [Phys. Rev. A 55, 3760 (1997)] is adapted to calculate the transition amplitude for a short laser pulse. Its application to a pulse with N optical cycles produces 2(N+1) saddle points in complex time, which form a characteristic 'smile.' Numerical calculations are performed for H{sup -} in a 5-cycle pulse with frequency 0.0043 a.u. and intensities of 10{sup 10}, 5x10{sup 10}, and 10{sup 11} W/cm{sup 2}, and for various carrier-envelope phases. We determine the spectrum of the photoelectrons as a function of both energy and emission angle, as well as the angle-integrated energy spectra and total detachment probabilities. Our calculations show that the dominant contribution to the transition amplitude is given by 5-6 central saddle points, which correspond to the strongest part of the pulse. We examine the dependence of the photoelectron angular distributions on the carrier-envelope phase and show that measuring such distributions can provide a way of determining this phase.

  5. High current DC negative ion source for cyclotron.

    PubMed

    Etoh, H; Onai, M; Aoki, Y; Mitsubori, H; Arakawa, Y; Sakuraba, J; Kato, T; Mitsumoto, T; Hiasa, T; Yajima, S; Shibata, T; Hatayama, A; Okumura, Y

    2016-02-01

    A filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In Cs-free operation, continuous H(-) beam of 10 mA and D(-) 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(-) 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(-) current, was 15 sccm in the Cs-free operation, while it decreased to 4 sccm in the Cs-seeded operation. The relationship between H(-) 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(-) current dependence on the arc power. PMID:26932017

  6. High-energy above-threshold detachment from negative ions

    SciTech Connect

    Gazibegovic-Busuladzic, A.; Milosevic, D.B.; Becker, W.

    2004-11-01

    Above-threshold detachment of electrons from negative ions by an elliptically polarized laser field is analyzed within the strong-field approximation. The low-energy part of the spectrum, that is, its structure and its apparent cutoff, strongly depends on the orbital quantum number l of the initial ground state. The high-energy part is characterized by the usual extended plateau caused by rescattering, which is essentially independent of the ground state. The potential that the returning electron experiences during rescattering is modeled by the sum of a polarization potential and a static potential. This rescattering potential does not have much effect on the shape of the plateau, but it does on its height. For H{sup -} (l=0), the yield of rescattered electrons is five orders of magnitude below the direct electrons, while for I{sup -} (l=1) the yields only differ by a factor of 40. We also analyze the dependence of the angle-resolved energy spectrum on the ellipticity of the laser field and confirm general symmetry properties. An angle-integrated elliptic dichroism parameter is introduced and analyzed.

  7. Mechanisms of hydrogen ion neutralization in an experimentally acidified lake

    SciTech Connect

    Cook, R.B.; Kelly, C.A.; Schindler, D.W.; Turner, M.A.

    1986-01-01

    The experimental acidification of Lake 223 (Experimental Lakes Area, northwestern Ontario) with sulfuric acid in 1976-1983 allowed a detailed examination of the capacity of the lake to neutralize hydrogen ion. A whole-lake alkalinity and ion budget for Lake 223 showed that 66-81% of the added sulfuric acid was neutralized by alkalinity production in the lake. Nearly 85% of in situ alkalinity production was accounted for by net loss of sulfate through bacterial sulfate reduction, coupled with iron reduction and iron sulfide formation, in littoral sediments (60%) and in the hypolimnion (25%). Exchange of hydrogen ion for calcium and manganese in the sediments accounted for 19% of the alkalinity generated, while other cations were net sinks for alkalinity. The seasonal production of 1000 ..mu..eq liter/sup -1/ alkalinity in the anoxic hypolimnion of this soft-water lake could be attributed to bacterial sulfate reduction coupled with iron sulfide formation, ammonium production, and iron (II) production. Only the alkalinity produced from bacterial sulfate reduction coupled with iron sulfide formation remained throughout the annual cycle.

  8. Improving efficiency of negative ion production in ion source with saddle antenna

    SciTech Connect

    Dudnikov, V. Johnson, R. P.; Murrey, S.; Pinnisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R.; Johnson, C.; Turvey, M.

    2014-02-15

    Extraction of negative ions from a saddle antenna radio-frequency surface plasma source is considered. Several versions of new plasma generators with different antennas and magnetic field configurations were tested in the smal Oak Ridge National Laboratory Spallation Neutron Source Test Stand. The efficiency of positive ion generation in plasma has been improved to 200 mA/cm{sup 2} kW from 2.5 mA/cm{sup 2} kW. A small oven was developed for cesiation by cesium compounds and alloy decomposition. After cesiation, a current of negative ions to the collector was increased from 1 mA to 10 mA with 1.5 kW RF power in the plasma and longitudinal magnetic field B{sub l} ∼ 250 G. The specific efficiency of H{sup −} production was increased to 20 mA/cm{sup 2} kW from 2.5 mA/cm{sup 2} kW.

  9. Kinetic modeling of particle dynamics in H- negative ion sources (invited)

    NASA Astrophysics Data System (ADS)

    Hatayama, A.; Shibata, T.; Nishioka, S.; Ohta, M.; Yasumoto, M.; Nishida, K.; Yamamoto, T.; Miyamoto, K.; Fukano, A.; Mizuno, T.

    2014-02-01

    Progress in the kinetic modeling of particle dynamics in H- negative ion source plasmas and their comparisons with experiments are reviewed, and discussed with some new results. Main focus is placed on the following two topics, which are important for the research and development of large negative ion sources and high power H- ion beams: (i) Effects of non-equilibrium features of EEDF (electron energy distribution function) on H- production, and (ii) extraction physics of H- ions and beam optics.

  10. Aberration of a negative ion beam caused by space charge effect.

    PubMed

    Miyamoto, K; Wada, S; Hatayama, A

    2010-02-01

    Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

  11. Vibrationally resolved negative ion photoelectron spectroscopic studies of niobium clusters

    SciTech Connect

    Green, S.M.E.; Alex, S.; Leopold, D.G.

    1996-12-31

    Negative ion photoelectron spectroscopy provides a means of obtaining vibrational data for atoms and small molecules {open_quotes}chemisorbed{close_quotes} on size-selected metal clusters. In the present study, Nb{sub 3}O{sup -}, Nb{sub 4}O{sup -} and Nb{sub 4}CO{sup -} were prepared in a flowing afterglow ion-molecule reactor equipped with a metal cathode cluster source. The 488 nm photoelectron spectrum of the mass-selected Nb{sub 3}O{sup -} anions shows a vertical transition to the ground state of neutral Nb{sub 3}O, with weak progressions in the Nb{sub 3}-O stretching (710{+-}20 cm{sup -1} in Nb{sub 3}O) and Nb, bending (320{+-}15 cm{sup -1}-in both Nb{sub 3}O and Nb{sub 3}O{sup -}) vibrational modes. These results indicate that the Nb{sub 3}O{sup -} anion, like Nb{sub 3}O and Nb{sub 3}O{sup +}, has a planar Ca{sub 2v} structure with the O atom bridging two Nb atoms. The Nb{sub 4}O{sup -} spectrum shows resolved transitions to the ground state of Nb{sub 3}O and to an excited electronic state lying 3050{+-}20 cm{sup -1} higher in energy. In analogy with the Nb{sub 4}O results, the 670{+-}20 cm{sup -1} frequency observed for the Nb{sub 4}O ground state is assigned to a metal-oxygen stretching mode, and the 215{+-}15 cm{sup -1} and 195{+-}15 cm{sup -1} frequencies observed in the ground and excited states, respectively, to a bending mode of the metal cluster. The electron affinities of Nb{sub 3}O and Nb{sub 4}O are 1.402 and 1.178 ({+-}0.006) eV, respectively. Preliminary, ongoing studies of mass selected Nb{sub 4}CO{sup -} anions prepared under a variety of source conditions thus far suggest the presence of two isomers, one with a greatly weakened but intact CO bond as indicated by a very low CO stretching frequency of about 1300 cm{sup -1} and the other with the dissociated C and O atoms bound separately to the niobium cluster.

  12. Long-pulse production of high current negative ion beam by using actively temperature controlled plasma grid for JT-60SA negative ion source

    SciTech Connect

    Kojima, A.; Hanada, M.; Yoshida, M.; Umeda, N.; Hiratsuka, J.; Kashiwagi, M.; Tobari, H.; Watanabe, K.; Grisham, L. R.

    2015-04-08

    The temperature control system of the large-size plasma grid has been developed to realize the long pulse production of high-current negative ions for JT-60SA. By using this prototype system for the JT-60SA ion source, 15 A negative ions has been sustained for 100 s for the first time, which is three times longer than that obtained in JT-60U. In this system, a high-temperature fluorinated fluid with a high boiling point of 270 degree Celsius is circulated in the cooling channels of the plasma grids (PG) where a cesium (Cs) coverage is formed to enhance the negative ion production. Because the PG temperature control had been applied to only 10% of the extraction area previously, the prototype PG with the full extraction area (110 cm × 45 cm) was developed to increase the negative ion current in this time. In the preliminary results of long pulse productions of high-current negative ions at a Cs conditioning phase, the negative ion production was gradually degraded in the last half of 100 s pulse where the temperature of an arc chamber wall was not saturated. From the spectroscopic measurements, it was found that the Cs flux released from the wall might affect to the negative ion production, which implied the wall temperature should be kept low to control the Cs flux to the PG for the long-pulse high-current production. The obtained results of long-pulse production and the PG temperature control method contributes the design of the ITER ion source.

  13. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 3. Estimating Surface Area Exposure by Deuterium Uptake

    NASA Astrophysics Data System (ADS)

    Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Donohoe, Gregory C.; Valentine, Stephen J.

    2016-03-01

    Gas-phase hydrogen deuterium exchange (HDX), collision cross section (CCS) measurement, and molecular dynamics simulation (MDS) techniques were utilized to develop and compare three methods for estimating the relative surface area exposure of separate peptide chains within bovine insulin ions. Electrosprayed [M - 3H]3- and [M - 5H]5- insulin ions produced a single conformer type with respective collision cross sections of 528 ± 5 Å2 and 808 ± 2 Å2. [M - 4H]4- ions were comprised of more compact (Ω = 676 ± 3 Å2) and diffuse (i.e., more elongated, Ω = 779 ± 3 Å2) ion conformer types. Ions were subjected to HDX in the drift tube using D2O as the reagent gas. Collision-induced dissociation was used to fragment mobility-selected, isotopically labeled [M - 4H]4- and [M - 5H]5- ions into the protein subchains. Deuterium uptake levels of each chain can be explained by limited inter-chain isotopic scrambling upon collisional activation. Using nominal ion structures from MDS and a hydrogen accessibility model, the deuterium uptake for each chain was correlated to its exposed surface area. In separate experiments, the per-residue deuterium content for the protonated and deprotonated ions of the synthetic peptide KKDDDDDIIKIIK were compared. The differences in deuterium content indicated the regional HDX accessibility for cations versus anions. Using ions of similar conformational type, this comparison highlights the complementary nature of HDX data obtained from positive- and negative-ion analysis.

  14. Optical model analyses of heavy ion fragmentation in hydrogen targets

    NASA Technical Reports Server (NTRS)

    Townsend, Lawrence W.

    1994-01-01

    Quantum-mechanical optical-model methods for calculating cross sections for the fragmentation of high-energy heavy ions by hydrogen targets are presented. The cross sections are calculated with a knockout-ablation collision formalism which has no arbitrary fitting parameters. Predictions of elemental production cross sections from the fragmentation of 1.2A Ge(V(La-139) nuclei and of isotope production cross sections from the fragmentation of 400A MeV(S-32) nuclei are in good agreement with recently reported experimental measurements.

  15. Novel materials for negative electrodes in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Pereira, Nathalie

    Carbonaceous materials are currently utilized as negative electrodes in commercial rechargeable Li-ion batteries. However, their low capacity prompted the search for alternative materials of higher capacity and good cycling stability in order to maximize the battery energy density and cycle life. Lithium alloys have long been considered as alternative negative electrode materials to substitute for the carbonaceous materials currently used in commercial rechargeable Li-ion batteries. However, they suffer from cracking caused by the large volume changes occurring during lithiation and delithiation. To better understand the alloys failure mechanism, various elements were tested and those that can alloy with lithium electrochemically were identified. Silicon showed extremely high capacity but poor cycle life. To investigate to which extent multiphase materials may improve cycle life, several binary metal-silicides were explored in search for improved cycling stability. Mg 2Si was the only compound of high capacity but it exhibited poor cycle life. Both addition of a matrix and decrease in particle size have been demonstrated to improve cycle life. Each effect has been investigated separately. Using tin-based powders of different size oxidized to various extent, we showed an increase in oxygen content, a particle size decrease and the formation of converted Sn-Sb compounds improved cycling stability. The effect of the matrix nature on the electrochemical properties was explored using Zn-based conversion materials. Upon reaction with lithium, ZnO and ZnS electrodes generated LiZn and a Li2O and Li2S matrix, respectively. The reversible process was identified as the Li-Zn alloying reaction, as obtained in pure metallic Zn electrodes. ZnO and ZnS failure mechanisms were also similar to metallic Zn. However, ZnS showed improved cycle life. LiZnN has been isolated by way of an electrochemical conversion reaction of Zn3N2 with lithium. We showed Zn3N 2 reversibly reacts with

  16. Negative ion rich plasmas in continuous and pulsed wave modes in a minimum-B magnetic field

    SciTech Connect

    Sahu, Debaprasad; Pandey, Shail; Aneja, Jyoti; Bhattacharjee, Sudeep

    2012-12-15

    Generation of hydrogen negative ion rich plasmas is investigated in continuous wave (CW) and pulse modulated (PM) wave modes of 2.45 GHz in a minimum-B magnetic field. The waves are launched directly into the plasma device and utilize wave particle resonances for high density plasma generation. In CW operation, the chamber is divided into two sections, namely, the source and downstream region, separated by a transverse magnetic field that allows only cold electrons ({approx}1 eV) into the downstream region helpful for the generation of negative ions. The H{sup -} density is measured by the second derivative beat method and is compared with the values obtained from a steady state model and the extracted current density. In the pulsed mode, temporal filtering generates negative ion rich plasmas in the afterglow phase. The H{sup -} density in the afterglow is estimated using saturation current ratio method and the results are compared with a time dependent model using particle balance equations. The essential idea in both the filtering techniques is to assist generation of negative ions and prevent its destruction by hot electrons.

  17. Negative ion rich plasmas in continuous and pulsed wave modes in a minimum-B magnetic field

    NASA Astrophysics Data System (ADS)

    Sahu, Debaprasad; Pandey, Shail; Aneja, Jyoti; Bhattacharjee, Sudeep

    2012-12-01

    Generation of hydrogen negative ion rich plasmas is investigated in continuous wave (CW) and pulse modulated (PM) wave modes of 2.45 GHz in a minimum-B magnetic field. The waves are launched directly into the plasma device and utilize wave particle resonances for high density plasma generation. In CW operation, the chamber is divided into two sections, namely, the source and downstream region, separated by a transverse magnetic field that allows only cold electrons (˜1 eV) into the downstream region helpful for the generation of negative ions. The H- density is measured by the second derivative beat method and is compared with the values obtained from a steady state model and the extracted current density. In the pulsed mode, temporal filtering generates negative ion rich plasmas in the afterglow phase. The H- density in the afterglow is estimated using saturation current ratio method and the results are compared with a time dependent model using particle balance equations. The essential idea in both the filtering techniques is to assist generation of negative ions and prevent its destruction by hot electrons.

  18. Letter: High-mass capabilities of positive-ion and negative-ion direct analysis in real time mass spectrometry.

    PubMed

    Gross, Jürgen H

    2016-01-01

    Of the ionic liquid 1-butyl-3-methylimidazolium (C(+)) tricyanomethide (A(-)) high-mass cluster ions of both positive ([C(n)A(n-1)](+)) and negative ([C(n-1)A(n)](-)) charge were generated and detected by direct analysis in real time (DART) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS). After optimization of the settings of the DART ionization source and of the mass analyzer ions of m/z values unprecedented in DART-MS were detected. Thus, the upper m/z limits of positive-ion and negative-ion DART- MS were substantially expanded. Negative-ion DART-MS delivered cluster ions up to [C(15)A(16)](-), m/z 3527 (nominal mass of monoisotopic ion), while positive-ion DART-MS even yielded ions up to [C(30)A(29)](+), m/z 6784. The identification of the cluster ions is supported by their accurate mass and exact mass differences corresponding to CA between adjacent cluster ion peaks.

  19. Effect of non-uniform electron energy distribution function on plasma production in large arc driven negative ion source.

    PubMed

    Shibata, T; Koga, S; Terasaki, R; Inoue, T; Dairaku, M; Kashiwagi, M; Taniguchi, M; Tobari, H; Tsuchida, K; Umeda, N; Watanabe, K; Hatayama, A

    2012-02-01

    Spatially non-uniform electron energy distribution function (EEDF) in an arc driven negative ion source (JAEA 10A negative ion source: 10 A NIS) is calculated numerically by a three-dimensional Monte Carlo kinetic model for electrons to understand spatial distribution of plasma production (such as atomic and ionic hydrogen (H(0)∕H(+)) production) in source chamber. The local EEDFs were directly calculated from electron orbits including electromagnetic effects and elastic∕inelastic collision forces. From the EEDF, spatial distributions of H(0)∕H(+) production rate were obtained. The results suggest that spatial non-uniformity of H(0)∕H(+) productions is enhanced by high energy component of EEDF.

  20. NEGATIVE-ION MASS SPECTROMETRY OF SULFONYLUREA HERBICIDES

    EPA Science Inventory

    Sulfonylurea herbicides have been studied using neg-ion desorption chem.-ionization (DCI) mass spectrometry (MS) and DCI-MS/MS techniques. Both {M-H]- and M.- ions were obsd. in the DCI mass spectra. The collisonally activated dissocn. (CAD) spectra were characteristic of the str...

  1. The effects of CO2 on the negative reactant ions of IMS

    NASA Technical Reports Server (NTRS)

    Spangler, Glenn E.

    1995-01-01

    In the presence of CO2, the negative reactant ions of ion mobility spectrometry (IMS) are ion clusters of CO4(-) and CO3(-). Methyl salicylate is ionized by the CO4(-)(H2O(n))(N2(m)) reactant ions, but not by the CO3(-)(H2O(n))(N2(m)) reactant ions. While the CO4(-) ions are formed by direct association, the CO3(-) ions require additional energy to be formed. The additional energy is provided by either excited neutral gas molecules in a metastable state or UV (ultraviolet) radiation.

  2. Above-threshold ionization of hydrogen and hydrogen-like ions by X-ray pulses

    NASA Astrophysics Data System (ADS)

    Bachau, Henri; Budriga, Olimpia; Dondera, Mihai; Florescu, Viorica

    2013-09-01

    This paper adresses the problem of above-threshold ionization (ATI) of hydrogen interacting with an intense X-ray electromagnetic field. Two approaches have been used. In the first approach, we calculate generalized differential and total cross sections based on second-order perturbation theory for the electron interaction with a monochromatic plane wave, with the A 2 and A · P contributions from the nonrelativistic Hamiltonian (including retardation) treated exactly. In the second approach, we solve the time-dependent Schrödinger equation (TDSE) for a pulsed plane wave using a spectral approach with a basis of oneelectron orbitals, calculated with L 2-integrable B-spline functions for the radial coordinate and spherical harmonics Y lm for the angular part. Retardation effects are included up to O(1/c), they induce extra terms forcing the resolution of the TDSE in a three dimensional space. Relativistic effects [of O (1/c 2)] are fully neglected. The isoelectronic series of hydrogen is explored in the range Z = 1 - 5 in both TDSE and perturbative approaches. Photoelectron angular distributions are obtained for photon energies of 1 keV and 3 keV for hydrogen, and photon energy of 25 keV for the hydrogenic ion B4+. Perturbative and TDSE calculations are compared.

  3. Above-threshold ionization of hydrogen and hydrogen-like ions by X-ray pulses

    NASA Astrophysics Data System (ADS)

    Bachau, Henri; Budriga, Olimpia; Dondera, Mihai; Florescu, Viorica

    2013-09-01

    This paper adresses the problem of above-threshold ionization (ATI) of hydrogen interacting with an intense X-ray electromagnetic field. Two approaches have been used. In the first approach, we calculate generalized differential and total cross sections based on second-order perturbation theory for the electron interaction with a monochromatic plane wave, with the A 2 and A · P contributions from the nonrelativistic Hamiltonian (including retardation) treated exactly. In the second approach, we solve the time-dependent Schrödinger equation (TDSE) for a pulsed plane wave using a spectral approach with a basis of oneelectron orbitals, calculated with L 2-integrable B-spline functions for the radial coordinate and spherical harmonics Y lm for the angular part. Retardation effects are included up to O(1/ c), they induce extra terms forcing the resolution of the TDSE in a three dimensional space. Relativistic effects [of O (1/ c 2)] are fully neglected. The isoelectronic series of hydrogen is explored in the range Z = 1 - 5 in both TDSE and perturbative approaches. Photoelectron angular distributions are obtained for photon energies of 1 keV and 3 keV for hydrogen, and photon energy of 25 keV for the hydrogenic ion B4+. Perturbative and TDSE calculations are compared.

  4. Soliton propagation in an inhomogeneous plasma at critical density of negative ions: Effects of gyratory and thermal motions of ions

    SciTech Connect

    Malik, Hitendra K.; Kawata, Shigeo

    2007-10-15

    The effects of gyratory and thermal motions of ions on soliton propagation in an inhomogeneous plasma that contains positive ions, negative ions, and electrons are studied at a critical density of negative ions. Since at this critical negative ion density the nonlinear term of the relevant Korteweg-deVries (KdV) equation vanishes, a higher order of nonlinearity is considered by retaining higher-order perturbation terms in the expansion of dependent quantities together with the appropriate set of stretched coordinates. Under this situation, time-dependent perturbation leads to the evolution of modified KdV solitons, which are governed by a modified form of the KdV equation that has an additional term due to the density gradient present in the plasma. On the basis of the solution of this equation and obliquely applied magnetic field, the effects of gyratory and thermal motions of ions are analyzed on the soliton propagation for three cases, n{sub n0}n{sub e0}, together with n{sub n0} (n{sub e0}) as the density of negative ions (electrons). The role of the negative ions in the evolution of the modes and the solitons is also discussed. Under the limiting cases, our calculations reduce to the ones obtained by other investigators in the past. This substantiates the generality of the present analysis.

  5. Soliton propagation in an inhomogeneous plasma at critical density of negative ions: Effects of gyratory and thermal motions of ions

    NASA Astrophysics Data System (ADS)

    Malik, Hitendra K.; Kawata, Shigeo

    2007-10-01

    The effects of gyratory and thermal motions of ions on soliton propagation in an inhomogeneous plasma that contains positive ions, negative ions, and electrons are studied at a critical density of negative ions. Since at this critical negative ion density the nonlinear term of the relevant Korteweg-deVries (KdV) equation vanishes, a higher order of nonlinearity is considered by retaining higher-order perturbation terms in the expansion of dependent quantities together with the appropriate set of stretched coordinates. Under this situation, time-dependent perturbation leads to the evolution of modified KdV solitons, which are governed by a modified form of the KdV equation that has an additional term due to the density gradient present in the plasma. On the basis of the solution of this equation and obliquely applied magnetic field, the effects of gyratory and thermal motions of ions are analyzed on the soliton propagation for three cases, nn0ne0, together with nn0 (ne0) as the density of negative ions (electrons). The role of the negative ions in the evolution of the modes and the solitons is also discussed. Under the limiting cases, our calculations reduce to the ones obtained by other investigators in the past. This substantiates the generality of the present analysis.

  6. Evidence for the existence of negative ions in the D and lower E regions at twilight

    NASA Technical Reports Server (NTRS)

    Kane, J. A.

    1972-01-01

    Evidence for negative ions in the lower ionosphere is based on the difference between simultaneously measured profiles of electron and positive ion density. The electron density profiles reported were obtained from ground-to-rocket radio wave absorption measurements while Gerdien ion traps were used to measure the positive ion profiles. Results from a series of three rockets launched from Thumba, India near sunset on 27 March, 1970 indicate that a significant number of negative ions are formed at altitudes as high as 95 km at twilight.

  7. Analysis of plasma dynamics of a negative ion source based on probe measurements

    SciTech Connect

    Bandyopadhyay, M.; Tanga, A.; Falter, H.D.; Franzen, P.; Heinemann, B.; Holtum, D.; Kraus, W.; Lackner, K.; McNeely, P.; Riedl, R.; Speth, E.; Wilhelm, R.

    2004-10-15

    Measurements and analysis of the plasma flow in an ion source made for negative ion extraction are reported in this article. The plasma flow has been measured using a Mach probe having two orthogonal probe heads. The plasma flow along the axis is driven by the electron pressure gradient, dragging along the ions via a measured ambipolar electric field against the collisional drag on the background gas. The force on the ions created by the electric field is mainly balanced by the collisional drag force. The collision between the ions and the background gas creates a pressure gradient along the flow direction. The one-dimensional plasma dynamic analysis supports the consistency of the experimental observations. The presence of a transverse magnetic filter reduces the plasma flow velocity, which could affect the negative ion production on the cesiated grid surface. A simple analysis shows that a strong plasma flow could enhance the surface production of negative ions.

  8. Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.; Singh, R.

    1985-01-01

    This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.

  9. Design of the Prototype Negative Ion Source for Neutral Beam Injector at ASIPP

    NASA Astrophysics Data System (ADS)

    Wei, Jianglong; Xie, Yahong; Liang, Lizhen; Gu, Yuming; Yi, Wei; Li, Jun; Hu, Chundong; Xie, Yuanlai; Jiang, Caichao; Tao, Ling; Sheng, Peng; Xu, Yongjian

    2016-09-01

    In order to support the design, manufacture and commissioning of the negative-ion-based neutral beam injection (NBI) system for the Chinese Fusion Engineering Test Reactor (CFETR), the Hefei utility negative ion test equipment with RF source (HUNTER) was proposed at ASIPP. A prototype negative ion source will be developed at first. The main bodies of plasma source and accelerator of the prototype negative ion source are similar to that of the ion source for EAST-NBI. But instead of the filament-arc driver, an RF driver is adopted for the prototype negative ion source to fulfill the requirement of long pulse operation. A cesium seeding system and a magnetic filter are added for enhancing the negative ion density near the plasma grid and minimizing co-extracted electrons. Besides, an ITER-like extraction system is applied inside the accelerator, where the negative ion beam is extracted and accelerated up to 50 kV. supported by National Natural Science Foundation of China (Nos. 11505224, 11575240, 11405207), the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB101001, 2013GB101002, 2013GB101003), International Science and Technology Cooperation Program of China (No. 2014DFG61950), and Foundation of ASIPP (No. DSJJ-14-JC07)

  10. Work function measurements during plasma exposition at conditions relevant in negative ion sources for the ITER neutral beam injection

    SciTech Connect

    Gutser, R.; Wimmer, C.; Fantz, U.

    2011-02-15

    Cesium seeded sources for surface generated negative hydrogen ions are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER. The stability and delivered current density depend highly on the work function during vacuum and plasma phases of the ion source. One of the most important quantities that affect the source performance is the work function. A modified photocurrent method was developed to measure the temporal behavior of the work function during and after cesium evaporation. The investigation of cesium exposed Mo and MoLa samples under ITER negative hydrogen ion based neutral beam injection relevant surface and plasma conditions showed the influence of impurities which result in a fast degradation when the plasma exposure or the cesium flux onto the sample is stopped. A minimum work function close to that of bulk cesium was obtained under the influence of the plasma exposition, while a significantly higher work function was observed under ITER-like vacuum conditions.

  11. Work function measurements during plasma exposition at conditions relevant in negative ion sources for the ITER neutral beam injection.

    PubMed

    Gutser, R; Wimmer, C; Fantz, U

    2011-02-01

    Cesium seeded sources for surface generated negative hydrogen ions are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER. The stability and delivered current density depend highly on the work function during vacuum and plasma phases of the ion source. One of the most important quantities that affect the source performance is the work function. A modified photocurrent method was developed to measure the temporal behavior of the work function during and after cesium evaporation. The investigation of cesium exposed Mo and MoLa samples under ITER negative hydrogen ion based neutral beam injection relevant surface and plasma conditions showed the influence of impurities which result in a fast degradation when the plasma exposure or the cesium flux onto the sample is stopped. A minimum work function close to that of bulk cesium was obtained under the influence of the plasma exposition, while a significantly higher work function was observed under ITER-like vacuum conditions.

  12. Negative Hyperconjugation versus Electronegativity: Vibrational Spectra of Free Fluorinated Alkoxide Ions in the Gas Phase.

    PubMed

    Oomens, Jos; Berden, Giel; Morton, Thomas Hellman

    2015-06-22

    CO stretching frequencies of free, gaseous, fluorinated alkoxide ions shift substantially to the blue, relative to those of corresponding alcohols complexed with ammonia. Free α-fluorinated ions, pentafluoroethoxide and heptafluoroisopropoxide anions, display further blue shifts relative to cases with only β-fluorination, providing experimental evidence for fluorine negative hyperconjugation. DFT analysis with the atoms in molecules (AIM) method confirms an increase in CO bond order for the α-fluorinated ions, demonstrating an increase in carbonyl character for the free ions.

  13. Magnetized retarding field energy analyzer measuring the particle flux and ion energy distribution of both positive and negative ions

    SciTech Connect

    Rafalskyi, Dmytro; Aanesland, Ane; Dudin, Stanislav

    2015-05-15

    This paper presents the development of a magnetized retarding field energy analyzer (MRFEA) used for positive and negative ion analysis. The two-stage analyzer combines a magnetic electron barrier and an electrostatic ion energy barrier allowing both positive and negative ions to be analyzed without the influence of electrons (co-extracted or created downstream). An optimal design of the MRFEA for ion-ion beams has been achieved by a comparative study of three different MRFEA configurations, and from this, scaling laws of an optimal magnetic field strength and topology have been deduced. The optimal design consists of a uniform magnetic field barrier created in a rectangular channel and an electrostatic barrier consisting of a single grid and a collector placed behind the magnetic field. The magnetic barrier alone provides an electron suppression ratio inside the analyzer of up to 6000, while keeping the ion energy resolution below 5 eV. The effective ion transparency combining the magnetic and electrostatic sections of the MRFEA is measured as a function of the ion energy. It is found that the ion transparency of the magnetic barrier increases almost linearly with increasing ion energy in the low-energy range (below 200 eV) and saturates at high ion energies. The ion transparency of the electrostatic section is almost constant and close to the optical transparency of the entrance grid. We show here that the MRFEA can provide both accurate ion flux and ion energy distribution measurements in various experimental setups with ion beams or plasmas run at low pressure and with ion energies above 10 eV.

  14. Magnetized retarding field energy analyzer measuring the particle flux and ion energy distribution of both positive and negative ions.

    PubMed

    Rafalskyi, Dmytro; Dudin, Stanislav; Aanesland, Ane

    2015-05-01

    This paper presents the development of a magnetized retarding field energy analyzer (MRFEA) used for positive and negative ion analysis. The two-stage analyzer combines a magnetic electron barrier and an electrostatic ion energy barrier allowing both positive and negative ions to be analyzed without the influence of electrons (co-extracted or created downstream). An optimal design of the MRFEA for ion-ion beams has been achieved by a comparative study of three different MRFEA configurations, and from this, scaling laws of an optimal magnetic field strength and topology have been deduced. The optimal design consists of a uniform magnetic field barrier created in a rectangular channel and an electrostatic barrier consisting of a single grid and a collector placed behind the magnetic field. The magnetic barrier alone provides an electron suppression ratio inside the analyzer of up to 6000, while keeping the ion energy resolution below 5 eV. The effective ion transparency combining the magnetic and electrostatic sections of the MRFEA is measured as a function of the ion energy. It is found that the ion transparency of the magnetic barrier increases almost linearly with increasing ion energy in the low-energy range (below 200 eV) and saturates at high ion energies. The ion transparency of the electrostatic section is almost constant and close to the optical transparency of the entrance grid. We show here that the MRFEA can provide both accurate ion flux and ion energy distribution measurements in various experimental setups with ion beams or plasmas run at low pressure and with ion energies above 10 eV. PMID:26026517

  15. Determination of N-linked glycosylation in viral glycoproteins by negative ion mass spectrometry and ion mobility

    PubMed Central

    Bitto, David; Harvey, David J.; Halldorsson, Steinar; Doores, Katie J.; Pritchard, Laura K.; Huiskonen, Juha T.; Bowden, Thomas A.; Crispin, Max

    2016-01-01

    Summary Glycan analysis of virion-derived glycoproteins is challenging due to the difficulties in glycoprotein isolation and low sample abundance. Here, we describe how ion mobility mass spectrometry can be used to obtain spectra from virion samples. We also describe how negative ion fragmentation of glycans can be used to probe structural features of virion glycans. PMID:26169737

  16. High-precision spectroscopy of hydrogen molecular ions

    NASA Astrophysics Data System (ADS)

    Zhong, Zhen-Xiang; Tong, Xin; Yan, Zong-Chao; Shi, Ting-Yun

    2015-05-01

    In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions ( and HD+), including nonrelativistic energy eigenvalues and relativistic and quantum electrodynamic corrections. In combination with high-precision measurements, it is feasible to precisely determine a molecular-based value of the proton-to-electron mass ratio. An experimental scheme is presented for measuring the rovibrational transition frequency (v,L) : (0,0) → (6,1) in HD+, which is currently underway at the Wuhan Institute of Physics and Mathematics. Project supported by the National Natural Science Foundation of China (Grants Nos. 11474316, 11004221, 10974224, and 11274348), the “Hundred Talent Program” of Chinese Academy of Sciences. Yan Zong-Chao was supported by NSERC, SHARCnet, ACEnet of Canada, and the CAS/SAFEA International Partnership Program for Creative Research Teams.

  17. RF Negative Ion Source Development at IPP Garching

    SciTech Connect

    Kraus, W.; McNeely, P.; Berger, M.; Christ-Koch, S.; Falter, H. D.; Fantz, U.; Franzen, P.; Froeschle, M.; Heinemann, B.; Leyer, S.; Riedl, R.; Speth, E.; Wuenderlich, D.

    2007-08-10

    IPP Garching is heavily involved in the development of an ion source for Neutral Beam Heating of the ITER Tokamak. RF driven ion sources have been successfully developed and are in operation on the ASDEX-Upgrade Tokamak for positive ion based NBH by the NB Heating group at IPP Garching. Building on this experience a RF driven H- ion source has been under development at IPP Garching as an alternative to the ITER reference design ion source. The number of test beds devoted to source development for ITER has increased from one (BATMAN) by the addition of two test beds (MANITU, RADI). This paper contains descriptions of the three test beds. Results on diagnostic development using laser photodetachment and cavity ringdown spectroscopy are given for BATMAN. The latest results for long pulse development on MANITU are presented including the to date longest pulse (600 s). As well, details of source modifications necessitated for pulses in excess of 100 s are given. The newest test bed RADI is still being commissioned and only technical details of the test bed are included in this paper. The final topic of the paper is an investigation into the effects of biasing the plasma grid.

  18. RF Negative Ion Source Development at IPP Garching

    NASA Astrophysics Data System (ADS)

    Kraus, W.; McNeely, P.; Berger, M.; Christ-Koch, S.; Falter, H. D.; Fantz, U.; Franzen, P.; Fröschle, M.; Heinemann, B.; Leyer, S.; Riedl, R.; Speth, E.; Wünderlich, D.

    2007-08-01

    IPP Garching is heavily involved in the development of an ion source for Neutral Beam Heating of the ITER Tokamak. RF driven ion sources have been successfully developed and are in operation on the ASDEX-Upgrade Tokamak for positive ion based NBH by the NB Heating group at IPP Garching. Building on this experience a RF driven H- ion source has been under development at IPP Garching as an alternative to the ITER reference design ion source. The number of test beds devoted to source development for ITER has increased from one (BATMAN) by the addition of two test beds (MANITU, RADI). This paper contains descriptions of the three test beds. Results on diagnostic development using laser photodetachment and cavity ringdown spectroscopy are given for BATMAN. The latest results for long pulse development on MANITU are presented including the to date longest pulse (600 s). As well, details of source modifications necessitated for pulses in excess of 100 s are given. The newest test bed RADI is still being commissioned and only technical details of the test bed are included in this paper. The final topic of the paper is an investigation into the effects of biasing the plasma grid.

  19. Trial of a negative ion generator device in remediating problems related to indoor air quality

    SciTech Connect

    Daniell, W.; Camp, J.; Horstman, S. )

    1991-06-01

    It has been suggested that supplementation of indoor air with negative ions can improve air quality. This study examined the effects of a negative ion-generator device on air contaminants and symptom reporting in two office buildings. Separate sets of functional and nonfunctional negative ion generators were monitored using a double blind, crossover design involving two 5-week exposure periods. There were no detectable direct or residual effects of negative ion generator use on air ion levels, airborn particulates, carbon dioxide levels, or symptom reporting. Symptom reporting declined at both sites initially and appeared to be consistent with placebo effect. Job dissatisfaction was an apparent contributor to symptom reporting, with a magnitude comparable to presumed effects of air quality. Further testing of such devices is needed before they should be considered for office air quality problems.

  20. Comparison of ONIX simulation results with experimental data from the BATMAN testbed for the study of negative ion extraction

    NASA Astrophysics Data System (ADS)

    Mochalskyy, Serhiy; Fantz, Ursel; Wünderlich, Dirk; Minea, Tiberiu

    2016-10-01

    The development of negative ion (NI) sources for the ITER neutral beam injector is strongly accompanied by modelling activities. The ONIX (Orsay Negative Ion eXtraction) code simulates the formation and extraction of negative hydrogen ions and co-extracted electrons produced in caesiated sources. In this paper the 3D geometry of the BATMAN extraction system, and the source characteristics such as the extraction and bias potential, and the 3D magnetic field were integrated in the model. Calculations were performed using plasma parameters experimentally obtained on BATMAN. The comparison of the ONIX calculated extracted NI density with the experimental results suggests that predictive calculations of the extraction of NIs are possible. The results show that for an ideal status of the Cs conditioning the extracted hydrogen NI current density could reach ~30 mA cm-2 at 10 kV and ~20 mA cm-2 at 5 kV extraction potential, with an electron/NI current density ratio of about 1, as measured in the experiments under the same plasma and source conditions. The dependency of the extracted NI current on the NI density in the bulk plasma region from both the modeling and the experiment was investigated. The separate distributions composing the NI beam originating from the plasma bulk region and the PG surface are presented for different NI plasma volume densities and NI emission rates from the plasma grid (PG) wall, respectively. The extracted current from the NIs produced at the Cs covered PG surface, initially moving towards the bulk plasma and then being bent towards the extraction surfaces, is lower compared to the extracted NI current from directly extracted surface produced ions.

  1. Control of redox reactivity of flavin and pterin coenzymes by metal ion coordination and hydrogen bonding.

    PubMed

    Fukuzumi, Shunichi; Kojima, Takahiko

    2008-03-01

    The electron-transfer activities of flavin and pterin coenzymes can be fine-tuned by coordination of metal ions, protonation and hydrogen bonding. Formation of hydrogen bonds with a hydrogen-bond receptor in metal-flavin complexes is made possible depending on the type of coordination bond that can leave the hydrogen-bonding sites. The electron-transfer catalytic functions of flavin and pterin coenzymes are described by showing a number of examples of both thermal and photochemical redox reactions, which proceed by controlling the electron-transfer reactivity of coenzymes with metal ion binding, protonation and hydrogen bonding.

  2. Negative-ion-based neutral beams for fusion

    SciTech Connect

    Cooper, W.S.; Anderson, O.A.; Chan, C.F.; Jackson, L.T.; Kunkel, W.B.; Kwan, J.W.; Leung, K.N.; Lietzke, A.F.; Purgalis, P.; Soroka, L.

    1987-10-01

    To maximize the usefulness of an engineering test reactor (e.g., ITER, TIBER), it is highly desirable that it operate under steady-state conditions. The most attractive option for maintaining the circulating current needed in the center of the plasma is the injection of powerful beams of neutral deuterium atoms. The beam simultaneously heats the plasma. At the energies required, in excess of 500 keV, such beams can be made by accelerating D/sup -/ ions and then removing the electron. Sources are being developed that generate the D/sup -/ ions in the volume of a specially constructed plasma discharge, without the addition of cesium. These sources must operate with minimum gas flow, to avoid stripping the D/sup -/ beam, and with minimum electron output. We are designing at LBL highly efficient electrostatic accelerators that combine electric strong-focusing with dc acceleration and offer the possibility of varying the beam energy at constant current while minimizing breakdown. Some form of rf acceleration may also be required. To minimize irradiation of the ion sources and accelerators, the D/sup -/ beam can be transported through a maze in the neutron shielding. The D/sup -/ ions can be converted to neutrals in a gas or plasma target, but advances in laser and mirror technology may make possible very efficient photodetachment systems by the time an ETR becomes operational. 9 refs., 4 figs.

  3. Accelerated High-Resolution Differential Ion Mobility Separations Using Hydrogen

    PubMed Central

    Shvartsburg, Alexandre A.; Smith, Richard D.

    2011-01-01

    The resolving power of differential ion mobility spectrometry (FAIMS) was dramatically increased recently by carrier gases comprising up to 75% He or various vapors, enabling many new applications. However, the need for resolution of complex mixtures is virtually open-ended and many topical analyses demand yet finer separations. Also, the resolving power gains are often at the expense of speed, in particular making high-resolution FAIMS incompatible with online liquid-phase separations. Here, we report FAIMS employing hydrogen, specifically in mixtures with N2 containing up to 90% H2. Such compositions raise the mobilities of all ions and thus the resolving power beyond that previously feasible, while avoiding the electrical breakdown inevitable in He-rich mixtures. The increases in resolving power and ensuing peak resolution are especially significant at H2 fractions above ~50%. Higher resolution can be exchanged for acceleration of the analyses by up to ~4 times, at least. For more mobile species such as multiply-charged peptides, this exchange is presently forced by the constraints of existing FAIMS devices, but future designs optimized for H2 should consistently improve resolution for all analytes. PMID:22074292

  4. Accelerated high-resolution differential ion mobility separations using hydrogen.

    PubMed

    Shvartsburg, Alexandre A; Smith, Richard D

    2011-12-01

    The resolving power of differential ion mobility spectrometry (FAIMS) was dramatically increased recently by carrier gases comprising up to 75% He or various vapors, enabling many new applications. However, the need for resolution of complex mixtures is virtually open-ended and many topical analyses demand yet finer separations. Also, the resolving power gains are often at the expense of speed, in particular making high-resolution FAIMS poorly compatible with online liquid-phase separations. Here, we report FAIMS employing hydrogen, specifically in mixtures with N(2) containing up to 90% H(2). Such compositions raise the mobilities of all ions and thus the resolving power beyond that previously feasible, while avoiding the electrical breakdown inevitable in He-rich mixtures. The increases in resolving power and ensuing peak resolution are especially significant at H(2) fractions above ~50%. Higher resolution can be exchanged for acceleration of the analyses by up to ~4 times. For more mobile species such as multiply charged peptides, this exchange is presently forced by the constraints of existing FAIMS devices, but future designs optimized for H(2) should consistently improve resolution for all analytes.

  5. MeV negative ion source from ultra-intense laser-matter interaction

    SciTech Connect

    Ter-Avetisyan, S.; Ramakrishna, B.; Doria, D.; Prasad, R.; Borghesi, M.; Andreev, A. A.; Steinke, S.; Schnuerer, M.; Nickles, P. V.; Tikhonchuk, V.

    2012-02-15

    Experimental demonstration of negative ion acceleration to MeV energies from sub-micron size droplets of water spray irradiated by ultra-intense laser pulses is presented. Thanks to the specific target configuration and laser parameters, more than 10{sup 9} negative ions per steradian solid angle in 5% energy bandwidth are accelerated in a stable and reliable manner. To our knowledge, by virtue of the ultra-short duration of the emission, this is by far the brightest negative ion source reported. The data also indicate the existence of beams of neutrals with at least similar numbers and energies.

  6. Negative ion beam injection apparatus with magnetic shield and electron removal means

    DOEpatents

    Anderson, Oscar A.; Chan, Chun F.; Leung, Ka-Ngo

    1994-01-01

    A negative ion source is constructed to produce H.sup.- ions without using Cesium. A high percentage of secondary electrons that typically accompany the extracted H.sup.- are trapped and eliminated from the beam by permanent magnets in the initial stage of acceleration. Penetration of the magnetic field from the permanent magnets into the ion source is minimized. This reduces the destructive effect the magnetic field could have on negative ion production and extraction from the source. A beam expansion section in the extractor results in a strongly converged final beam.

  7. Characterization of the ITER model negative ion source during long pulse operation

    SciTech Connect

    Hemsworth, R.S.; Boilson, D.; Crowley, B.; Homfray, D.; Esch, H.P.L. de; Krylov, A.; Svensson, L.

    2006-03-15

    It is foreseen to operate the neutral beam system of the International Thermonuclear Experimental Reactor (ITER) for pulse lengths extending up to 1 h. The performance of the KAMABOKO III negative ion source, which is a model of the source designed for ITER, is being studied on the MANTIS test bed at Cadarache. This article reports the latest results from the characterization of the ion source, in particular electron energy distribution measurements and the comparison between positive ion and negative ion extraction from the source.

  8. Kinetic modeling of particle dynamics in H{sup −} negative ion sources (invited)

    SciTech Connect

    Hatayama, A. Shibata, T.; Nishioka, S.; Ohta, M.; Yasumoto, M.; Nishida, K.; Yamamoto, T.; Miyamoto, K.; Fukano, A.; Mizuno, T.

    2014-02-15

    Progress in the kinetic modeling of particle dynamics in H{sup −} negative ion source plasmas and their comparisons with experiments are reviewed, and discussed with some new results. Main focus is placed on the following two topics, which are important for the research and development of large negative ion sources and high power H{sup −} ion beams: (i) Effects of non-equilibrium features of EEDF (electron energy distribution function) on H{sup −} production, and (ii) extraction physics of H{sup −} ions and beam optics.

  9. The description of charge transfer in fast negative ions scattering on water covered Si(100) surfaces

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Qiu, Shunli; Liu, Pinyang; Xiong, Feifei; Lu, Jianjie; Liu, Yuefeng; Li, Guopeng; Liu, Yiran; Ren, Fei; Xiao, Yunqing; Gao, Lei; Zhao, Qiushuang; Ding, Bin; Li, Yuan; Guo, Yanling; Chen, Ximeng

    2016-11-01

    Doping has significantly affected the characteristics and performance of semiconductor electronic devices. In this work, we study the charge transfer processes for 8.5-22.5 keV C- and F- ions scattering on H2O-terminated p-type Si(100) surfaces with two different doping concentrations. We find that doping has no influence on negative-ion formation for fast collisions in this relatively high energy range. Moreover, we build a model to calculate negative ion fractions including the contribution from positive ions. The calculations support the nonadiabatic feature of charge transfer.

  10. Modeling of surface-dominated plasmas: From electric thruster to negative ion source

    SciTech Connect

    Taccogna, F.; Schneider, R.; Longo, S.; Capitelli, M.

    2008-02-15

    This contribution shows two important applications of the particle-in-cell/monte Carlo technique on ion sources: modeling of the Hall thruster SPT-100 for space propulsion and of the rf negative ion source for ITER neutral beam injection. In the first case translational degrees of freedom are involved, while in the second case inner degrees of freedom (vibrational levels) are excited. Computational results show how in both cases, plasma-wall and gas-wall interactions play a dominant role. These are secondary electron emission from the lateral ceramic wall of SPT-100 and electron capture from caesiated surfaces by positive ions and atoms in the rf negative ion source.

  11. Electron density measurement of cesium seeded negative ion source by surface wave probe

    SciTech Connect

    Kisaki, M.; Tsumori, K.; Nakano, H.; Ikeda, K.; Osakabe, M.; Nagaoka, K.; Shibuya, M.; Sato, M.; Sekiguchi, H.; Komada, S.; Kondo, T.; Hayashi, H.; Asano, E.; Takeiri, Y.; Kaneko, O.

    2012-02-15

    Electron density measurements of a large-scaled negative ion source were carried out with a surface wave probe. By comparison of the electron densities determined with the surface wave probe and a Langmuir probe, it was confirmed that the surface wave probe is highly available for diagnostic of the electron density in H{sup -} ion sources. In addition, it was found that the ratio of the electron density to the H{sup -} ion density dramatically decreases with increase of a bias voltage and the H{sup -} ions become dominant negative particles at the bias voltage of more than 6 V.

  12. Hydrogen evolution at the negative electrode of the all-vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Sun, Che-Nan; Delnick, Frank M.; Baggetto, Loïc; Veith, Gabriel M.; Zawodzinski, Thomas A.

    2014-02-01

    This work demonstrates a quantitative method to determine the hydrogen evolution rate occurring at the negative carbon electrode of the all vanadium redox flow battery (VRFB). Two carbon papers examined by buoyancy measurements yield distinct hydrogen formation rates (0.170 and 0.005 μmol min-1 g-1). The carbon papers have been characterized using electron microscopy, nitrogen gas adsorption, capacitance measurement by electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). We find that the specific electrochemical surface area (ECSA) of the carbon material has a strong influence on the hydrogen generation rate. This is discussed in light of the use of high surface area material to obtain high reaction rates in the VRFB.

  13. THE ROLE OF THE ACTIVITY COEFFICIENT OF THE HYDROGEN ION IN THE HYDROLYSIS OF GELATIN.

    PubMed

    Northrop, J H

    1921-07-20

    1. The hydrolysis of gelatin at a constant hydrogen ion concentration follows the course of a monomolecular reaction for about one-third of the reaction. 2. If the hydrogen ion concentration is not kept constant the amount of hydrolysis in certain ranges of acidity is proportional to the square root of the time (Schütz's rule). 3. The velocity of hydrolysis in strongly acid solution (pH less than 2.0) is directly proportional to the hydrogen ion concentration as determined by the hydrogen electrode i.e., the "activity;" it is not proportional to the hydrogen ion concentration as determined by the conductivity ratio. 4. The addition of neutral salts increases the velocity of hydrolysis and the hydrogen ion concentration (as determined by the hydrogen electrode) to approximately the same extent. 5. The velocity in strongly alkaline solutions (pH greater than 10) is directly proportional to the hydroxyl ion concentration. 6. Between pH 2.0 and pH 10.0 the rate of hydrolysis is approximately constant and very much greater than would be calculated from the hydrogen and hydroxyl ion concentration. This may be roughly accounted for by the assumption that the uncombined gelatin hydrolyzes much more rapidly than the gelatin salt.

  14. System integration of RF based negative ion experimental facility at IPR

    NASA Astrophysics Data System (ADS)

    Bansal, G.; Bandyopadhyay, M.; Singh, M. J.; Gahlaut, A.; Soni, J.; Pandya, K.; Parmar, K. G.; Sonara, J.; Chakraborty, A.

    2010-02-01

    The setting up of RF based negative ion experimental facility shall witness the beginning of experiments on the negative ion source fusion applications in India. A 1 MHz RF generator shall launch 100 kW RF power into a single driver on the plasma source to produce a plasma of density ~5 × 1012 cm-3. The source can deliver a negative ion beam of ~10 A with a current density of ~30 mA/cm2 and accelerated to 35 kV through an electrostatic ion accelerator. The experimental system is similar to a RF based negative ion source, BATMAN, presently operating at IPP. The subsystems for source operation are designed and procured principally from indigenous resources, keeping the IPP configuration as a base line. The operation of negative ion source is supported by many subsystems e.g. vacuum pumping system with gate valves, cooling water system, gas feed system, cesium delivery system, RF generator, high voltage power supplies, data acquisition and control system, and different diagnostics. The first experiments of negative ion source are expected to start at IPR from the middle of 2009.

  15. Germanium as negative electrode material for sodium-ion batteries

    SciTech Connect

    Baggetto, Loic; Keum, Jong Kahk; Browning, Jim; Veith, Gabriel M

    2013-01-01

    Germanium electrodes show a reversible Na-ion reaction at potentials of 0.15 and 0.6 V during discharge and charge, respectively. The reaction is accompanied with a reversible capacity close to 350 mAh g-1, which matches the value expected for the formation of NaGe. The electrode capacity retention is stable over 15 cycles but declines somewhat rapidly afterwards. This decline is typical for alloying systems undergoing large volume expansion, and calls for engineering solutions to confine the mechanical stress and control the electrolyte decomposition reactions that are likely to be the main sources of degradations. The rate performance results highlight the huge potential of nanosized germanium as a potential Na-ion anode. The reaction kinetics is found to be very good with about 220 mAh g-1 delivered at 170 C. Finally, the preliminary XRD results do not reveal the formation of crystalline phases at full (dis)charge.

  16. N-(1-naphthyl) ethylenediamine dinitrate: a new matrix for negative ion MALDI-TOF MS analysis of small molecules.

    PubMed

    Chen, Rui; Chen, Suming; Xiong, Caiqiao; Ding, Xunlei; Wu, Chih-Che; Chang, Huan-Cheng; Xiong, Shaoxiang; Nie, Zongxiu

    2012-09-01

    An organic salt, N-(1-naphthyl) ethylenediamine dinitrate (NEDN), with rationally designed properties of a strong UV absorbing chromophore, hydrogen binding and nitrate anion donors, has been employed as a matrix to analyze small molecules (m/z < 1000) such as oligosaccharides, peptides, metabolites and explosives using negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Compared with conventional matrixes such as α-cyano-4-hydroxycinnamic acid (CCA) and 2,5-dihydroxybenzoic acid (DHB), NEDN provides a significant improvement in detection sensitivity and yields very few matrix-associated fragment and cluster ions interfering with MS analysis. For low-molecular-weight saccharides, the lowest detection limit achieved ranges from 500 amol to 5 pmol, depending on the molecular weight and the structure of the analytes. Additionally, the mass spectra in the lower mass range (m/z < 200) consist of only nitrate and nitric acid cluster ions, making the matrix particularly useful for structural identification of oligosaccharides by post-source decay (PSD) MALDI-MS. Such a characteristic is illustrated by using maltoheptaose as a model system. This work demonstrates that NEDN is a novel negative ion-mode matrix for MALDI-MS analysis of small molecules with nitrate anion attachment.

  17. N-(1-Naphthyl) Ethylenediamine Dinitrate: A New Matrix for Negative Ion MALDI-TOF MS Analysis of Small Molecules

    NASA Astrophysics Data System (ADS)

    Chen, Rui; Chen, Suming; Xiong, Caiqiao; Ding, Xunlei; Wu, Chih-Che; Chang, Huan-Cheng; Xiong, Shaoxiang; Nie, Zongxiu

    2012-09-01

    An organic salt, N-(1-naphthyl) ethylenediamine dinitrate (NEDN), with rationally designed properties of a strong UV absorbing chromophore, hydrogen binding and nitrate anion donors, has been employed as a matrix to analyze small molecules ( m/z < 1000) such as oligosaccharides, peptides, metabolites and explosives using negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Compared with conventional matrixes such as α-cyano-4-hydroxycinnamic acid (CCA) and 2,5-dihydroxybenzoic acid (DHB), NEDN provides a significant improvement in detection sensitivity and yields very few matrix-associated fragment and cluster ions interfering with MS analysis. For low-molecular-weight saccharides, the lowest detection limit achieved ranges from 500 amol to 5 pmol, depending on the molecular weight and the structure of the analytes. Additionally, the mass spectra in the lower mass range ( m/z < 200) consist of only nitrate and nitric acid cluster ions, making the matrix particularly useful for structural identification of oligosaccharides by post-source decay (PSD) MALDI-MS. Such a characteristic is illustrated by using maltoheptaose as a model system. This work demonstrates that NEDN is a novel negative ion-mode matrix for MALDI-MS analysis of small molecules with nitrate anion attachment.

  18. Metallic contamination in hydrogen plasma immersion ion implantation of silicon

    NASA Astrophysics Data System (ADS)

    Chu, Paul K.; Fu, Ricky K. Y.; Zeng, Xuchu; Kwok, Dixon T. K.

    2001-10-01

    In plasma immersion ion implantation (PIII), ions bombard all surfaces inside the PIII vacuum chamber, especially the negatively pulsed biased sample stage and to a lesser extent the interior of the vacuum chamber. As a result, contaminants sputtered from these exposed surfaces can be reimplanted into or adsorb on the silicon wafer. Using particle-in-cell theoretical simulation, we determine the relative ion doses incident on the top, side, and bottom surfaces of three typical sample chuck configurations: (i) a bare conducting stage with the entire sample platen and high-voltage feedthrough/supporting rod exposed and under a high voltage, (ii) a stage with only the sample platen exposed to the plasma but the high-voltage feedthrough protected by an insulating quartz shroud, and (iii) a bare stage with a silicon extension or guard ring to reduce the number of ions bombarding the side and bottom of the sample platen. Our simulation results reveal that the ratio of the incident dose impacting the top of the sample platen to that impacting the side and bottom of the sample stage can be improved to 49% using a guard ring. To corroborate our theoretical results, we experimentally determine the amounts of metallic contaminants on 100 mm silicon wafers implanted using a bare chuck and with a 150 mm silicon wafer inserted between the 100 mm wafer and sample stage to imitate the guard ring. We also discuss the effectiveness of a replaceable all-silicon liner inside the vacuum chamber to address the second source of contamination, that from the interior wall of the vacuum chamber. Our results indicate a significant improvement when an all-silicon liner and silicon guard ring are used simultaneously.

  19. THE SIGNIFICANCE OF THE HYDROGEN ION CONCENTRATION FOR THE DIGESTION OF PROTEINS BY PEPSIN.

    PubMed

    Northrop, J H

    1920-11-20

    depress the ionization of the protein salt by increasing the concentration of the common anion. The hydrogen ion concentration is, therefore, no longer an indicator of the amount of ionized protein present, since this quantity is now determined by the anion concentration. Hence on the acid side of the optimum the addition of the same concentration of anion should have the same influence on the rate of digestion irrespective of whether it is combined with hydrogen or some other ion (provided, of course, that there is no other secondary effect of the other ion). The proposed mechanism is very similar to that suggested by Stieglitz and his coworkers for the hydrolysis of the imido esters. Pekelharing and Ringer have shown that pure pepsin in acid solution is always negatively charged; i.e., it is an anion. The experiments described above show further that it behaves just as would be expected of any anion in the presence of a salt containing the protein ion as the cation and as has been shown by Loeb to be the case with inorganic anions. Nothing has been said in regard to the quantitative agreement between the increasing amounts of ionized protein found in the solution (as shown by the conductivity values) and the amount predicted by the hydrolysis theory of the formation of salts of weak bases and strong acids. There is little doubt that the values are in qualitative agreement with such a theory. In order to make a quantitative comparison, however, it would be necessary to know the ionization constant of the protein and of the protein salt and also the number of hydroxyl (or amino) groups in the protein molecule as well as the molecular weight of the protein. Since these values are not known with any degree of certainty there appears to be no value at present in attempting to apply the hydrolysis equations to the data obtained. It it clear that the hypothesis as outlined above for the hydrolysis of proteins by pepsin cannot be extended directly to enzymes in general, since

  20. Modified Korteweg--deVries solitons in a warm plasma with negative ions

    SciTech Connect

    Kalita, B.C. , India ) Kalita, M.K. )

    1990-03-01

    The propagation of ion-acoustic solitons in a warm plasma in the presence of negative ions has been investigated theoretically through the modified Korteweg--deVries (KdV) equation. In the case of the first-order velocity perturbation of the positive ions bearing a constant ratio to that of the negative ions, the existence of both compressive and rarefactive solitons at different critical densities for different temperature ratios has been established when the mass ratio is greater than unity. It is also demonstrated in this case that no modified KdV soliton exists at the critical density in a warm plasma with negative ions when the mass ratio is less than unity.

  1. A negative ion beam application for improving biocompatibility of polystyrene surface

    NASA Astrophysics Data System (ADS)

    Ishikawa, Junzo; Tsuji, Hiroshi; Sato, Hiroko; Sasaki, Hitoshi; Gotoh, Yasuhito

    2001-07-01

    Improving biocompatibility of polystyrene surface by negative-ion implantation was investigated in respect to two kinds of cells: human umbilical vascular endothelial cells (HUVEC) and neurons (rat adrenal phechromocytoma: PC-12h). Negative ions of silver were implanted to non-treated polystyrene dishes (NTPS) at conditions of 20 keV and 3×1015ions/cm2 with or without a pattering mask with narrow slits array of 60 μm in width. Negative ions were used to avoid charge-up problem. The contact angle of pure water on ion-implanted NTPS surface was about 75°, which was lower than 86° for the original surface of NTPS. It was found from XPS surface analysis that this change to hydrophilic surface was caused by introduced functional groups of C-O, C=O, and O-C=O, during and after the ion implantation. After cell culture experiment, HUVEC cells attached only on the ion-implanted region of NTPS. On the ion-implanted narrow region with a width of 60 μm, attached HUVEC cells aligned with a longitudinal direction. As for PC-12h, the neuron cells also showed the same selective attachment property on the patterned NTPS surface by ion implantation. Besides, neurites of neural protrusion extended from cell body were also attached only on the ion-implanted region.

  2. Detection of artificially created negative ion clouds with incoherent scatter radar

    NASA Technical Reports Server (NTRS)

    Sultan, Peter J.; Mendillo, Michael; Oliver, William L.; Holt, John M.

    1992-01-01

    The physical mechanisms by which negative ions change the shape of the incoherent scatter spectrum, and the way in which shape changes may be used to detect the presence of heavy positive and negative ions in an ambient ionosphere are investigated. In order to detect heavy negative ions, the temperature structure of the ionosphere is fixed to a prevent average measurement, and any changes in spectral shape during the experiment are interpreted as being caused by changes in composition, and not by changes in the temperature ratio Te/Ti. The spatial and temporal development of heavy negative ion plasma clouds created during four active chemical release experiments was observed. Concentrations of 10-40-percent SF6(-) were detected in SPINEX 1, SPINEX 2, and IMS data sets. An average uncertainty of +/-10-percent SF6(-) is present in all three experiments. Concentrations of 30-percent Br(-) were detected in the NICARE 1 release, with uncertainties of +/-4 percent.

  3. Peripheral nerve regeneration through a silicone chamber implanted with negative carbon ions: Possibility to clinical application

    NASA Astrophysics Data System (ADS)

    Ikeguchi, Ryosuke; Kakinoki, Ryosuke; Tsuji, Hiroshi; Yasuda, Tadashi; Matsuda, Shuichi

    2014-08-01

    We investigated whether a tube with its inner surface implanted with negative-charged carbon ions (C- ions) would enable axons to extend over a distance greater than 10 mm. The tube was found to support nerves regenerating across a 15-mm-long inter-stump gap. We also investigated whether a C- ion-implanted tube pretreated with basic fibroblast growth factor (bFGF) promotes peripheral nerve regeneration. The C- ion implanted tube accelerated nerve regeneration, and this effect was enhanced by bFGF. Silicone treated with C- ions showed increased hydrophilic properties and cellular affinity, and axon regeneration was promoted with this increased biocompatibility.

  4. A Benign, Low Z Electron Capture Agent for Negative Ion TPCs

    NASA Technical Reports Server (NTRS)

    Martoff, C. J.; Dion, M. P.; Hosack, M.; Barton, D.; Black, J. K.

    2008-01-01

    We have identified nitromethane (CH3NO2) as an effective electron capture agent for negative ion TPCs (NITPCs). We present drift velocity and longitudinal diffusion measurements for negative ion gas mixtures using nitromethane as the capture agent. Not only is nitromethane substantially more benign than the only other identified capture agent, CS2, but its low atomic number will enable the use of the NITPC as a photoelectric X-ray polarimeter in the 1-10 keV band.

  5. A novel method to determine the diffusion coefficient of hydrogen ion in ruthenium oxide films

    NASA Astrophysics Data System (ADS)

    Yu, George T.; Yen, S. K.

    2002-10-01

    Hydrogen ion diffusion in ruthenium oxide film is of significant interest because of its importance in capacitor, sensor and catalyst applications. In this study, a method based on potential-pH response measurement was used to determine hydrogen ion diffusion in ruthenium oxide films. The drift in the potential-pH response is believed to be due to the hydrated layer, which affects hydrogen ion diffusion onto the oxide film of the pH sensor. Hydrogen ion diffusion coefficient of ruthenium oxide films obtained from this method was 6×10 -14 cm2/ s. The unique feature of the potential-pH response method is its relatively simple experimental procedure, which eliminates complications arising from surface related effects and/or presence of hydrogen traps in membrane such as those found in the conventional permeation method.

  6. Surface Dependent Electron and Negative Ion Density in Inductively Coupled Discharges

    SciTech Connect

    Blain, M.G.; Hamilton, T.W.; Hebner, G.A.; Jarecki, R.L.; Nichols, C.A.

    1999-01-18

    Electron and negative ion density have been measured in a modfied Applied Materials DPS metal etch chamber using gas mixtures of BCl{sub 3}, Cl{sub 2} and Ar. Measurements were performed for four dflerent substrate types to examine the influence of surface material on the bulk plasma properties; aluminurq alumina, photoresist and 50 percent patterned aluminum / photoresist. Electron densities in the Cl{sub 2} / BCl{sub 3} mixtures varied from 0.25 to 4 x 10{sup 11} cm{sup -3}. Photodetachment measurements of the negative ion density indicate that the negative ion density was smaller than the electron density and that the electron to negative ion density ratio varied between 1 and 6. The presence of photoresist had a dominant intluence on the electron and negative ion density compared to alumina and aluminum surfaces. In most cases, the electron density above wafers covered with photoresist was a factor of two lower while the negative ion density was a factor of two higher than the aluminum or alumina surfaces.

  7. Improvement in both giant magnetoresistance and exchange bias through hydrogen ion irradiation at low energy

    SciTech Connect

    Shim, Jaechul; Han, Yoonsung; Lee, Jinwon; Hong, Jongill

    2008-09-01

    Irradiation of IrMn-based spin valves with 550 eV hydrogen ions increased their giant magnetoresistance and exchange bias by 20% and 60%, respectively. This significant enhancement stems from the strong (111) texture and small mosaic spread of the IrMn antiferromagnet that resulted from the microstructural reconstruction caused by the energy transfer during the bombardment by hydrogen ions, as well as by the narrow dispersion in the exchange bias. Irradiation with the hydrogen ion at low energy can improve the properties of spin valves without resulting in undue degradation in the performance or the microstructure.

  8. High voltage holding in the negative ion sources with cesium deposition.

    PubMed

    Belchenko, Yu; Abdrashitov, G; Ivanov, A; Sanin, A; Sotnikov, O

    2016-02-01

    High voltage holding of the large surface-plasma negative ion source with cesium deposition was studied. It was found that heating of ion-optical system electrodes to temperature >100 °C facilitates the source conditioning by high voltage pulses in vacuum and by beam shots. The procedure of electrode conditioning and the data on high-voltage holding in the negative ion source with small cesium seed are described. The mechanism of high voltage holding improvement by depletion of cesium coverage is discussed.

  9. MeV negative ion generation from ultra-intense laser interaction with a water spray

    SciTech Connect

    Ter-Avetisyan, S.; Ramakrishna, B.; Borghesi, M.; Doria, D.; Zepf, M.; Sarri, G.; Ehrentraut, L.; Steinke, S.; Sandner, W.; Schnuerer, M.; Andreev, A.; Nickles, P. V.; Tikhonchuk, V.

    2011-08-01

    MeV negative oxygen ions are obtained from a water spray target irradiated by high intensity (5 x 10{sup 19} W/cm{sup 2}) and ultrashort (50 fs) laser pulses. Generation of negative ions is ascribed to electron-capture processes that the laser-accelerated high-energy positive ion experiences when it interacts with atoms in the spray. This mechanism implies the existence of a large number of MeV neutral oxygen atoms, which is consistent with indirect experimental evidence.

  10. High voltage holding in the negative ion sources with cesium deposition.

    PubMed

    Belchenko, Yu; Abdrashitov, G; Ivanov, A; Sanin, A; Sotnikov, O

    2016-02-01

    High voltage holding of the large surface-plasma negative ion source with cesium deposition was studied. It was found that heating of ion-optical system electrodes to temperature >100 °C facilitates the source conditioning by high voltage pulses in vacuum and by beam shots. The procedure of electrode conditioning and the data on high-voltage holding in the negative ion source with small cesium seed are described. The mechanism of high voltage holding improvement by depletion of cesium coverage is discussed. PMID:26932002

  11. Fractionation of inorganic arsenic by adjusting hydrogen ion concentration.

    PubMed

    Oliveira, Andrea; Gonzalez, Mario Henrique; Queiroz, Helena Müller; Cadore, Solange

    2016-12-15

    The inorganic fraction of arsenic species, iAs=∑[As(III)+As(V)] present in fish samples can be quantified in the presence of other arsenic species also found in fishes, such as: monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine (AsB). The toxic arsenic fraction was selected taking into account the dissociation constants of these arsenic species in different hydrogen ions concentration leading to the arsine formation from iAs compounds detected as As(III) by HG AAS. For thus, a microwave assisted extraction was carried out using HCl 1molL(-1) in order to maintain the integrity of the arsenic species in this mild extraction media. Recovery experiments were done for iAs fraction, in the presence of other arsenic species. The recovery values obtained for iAs fraction added were quantitative about 87-107% (for N=3, RSD⩽3%). The limit of detection (LOD), and the limit of quantification (LOQ), were 5μgkg(-1) and 16μgkg(-1) respectively. PMID:27451157

  12. Ion aggregation in high salt solutions. V. Graph entropy analyses of ion aggregate structure and water hydrogen bonding network.

    PubMed

    Choi, Jun-Ho; Cho, Minhaeng

    2016-05-28

    Dissolved ions in water tend to form polydisperse ion aggregates such as ion pairs, relatively compact ion clusters, and even spatially extended ion networks with increasing salt concentration. Combining molecular dynamics simulation and graph theoretical analysis methods, we recently studied morphological structures of ion aggregates with distinctively different characteristics. They can be distinguished from each other by calculating various spectral graph theoretical properties such as eigenvalues and eigenvectors of adjacency matrices of ion aggregates and water hydrogen-bonding networks, minimum path lengths, clustering coefficients, and degree distributions. Here, we focus on percolation and graph entropic properties of ion aggregates and water hydrogen-bonding networks in high salt solutions. Ion network-forming K(+) and SCN(-) ions at high concentrations show a percolating behavior in their aqueous solutions, but ion cluster-forming ions in NaCl solutions do not show such a transition from isolated ion aggregates to percolating ion-water mixture morphology. Despite that the ion aggregate structures are strikingly different for either cluster- or network-forming ions in high salt solutions, it is interesting that the water structures remain insensitive to the electrostatic properties, such as charge densities and polydentate properties, of dissolved ions, and morphological structures of water H-bonding networks appear to be highly robust regardless of the nature and concentration of salt. We anticipate that the present graph entropy analysis results would be of use in understanding a variety of anomalous behaviors of interfacial water around biomolecules as well as electric conductivities of high electrolyte solutions.

  13. Ion aggregation in high salt solutions. V. Graph entropy analyses of ion aggregate structure and water hydrogen bonding network

    NASA Astrophysics Data System (ADS)

    Choi, Jun-Ho; Cho, Minhaeng

    2016-05-01

    Dissolved ions in water tend to form polydisperse ion aggregates such as ion pairs, relatively compact ion clusters, and even spatially extended ion networks with increasing salt concentration. Combining molecular dynamics simulation and graph theoretical analysis methods, we recently studied morphological structures of ion aggregates with distinctively different characteristics. They can be distinguished from each other by calculating various spectral graph theoretical properties such as eigenvalues and eigenvectors of adjacency matrices of ion aggregates and water hydrogen-bonding networks, minimum path lengths, clustering coefficients, and degree distributions. Here, we focus on percolation and graph entropic properties of ion aggregates and water hydrogen-bonding networks in high salt solutions. Ion network-forming K+ and SCN- ions at high concentrations show a percolating behavior in their aqueous solutions, but ion cluster-forming ions in NaCl solutions do not show such a transition from isolated ion aggregates to percolating ion-water mixture morphology. Despite that the ion aggregate structures are strikingly different for either cluster- or network-forming ions in high salt solutions, it is interesting that the water structures remain insensitive to the electrostatic properties, such as charge densities and polydentate properties, of dissolved ions, and morphological structures of water H-bonding networks appear to be highly robust regardless of the nature and concentration of salt. We anticipate that the present graph entropy analysis results would be of use in understanding a variety of anomalous behaviors of interfacial water around biomolecules as well as electric conductivities of high electrolyte solutions.

  14. Vacuum insulation of the high energy negative ion source for fusion applicationa)

    NASA Astrophysics Data System (ADS)

    Kojima, A.; Hanada, M.; Hilmi, A.; Inoue, T.; Watanabe, K.; Taniguchi, M.; Kashiwagi, M.; Umeda, N.; Tobari, H.; Kobayashi, S.; Yamano, Y.; Grisham, L. R.

    2012-02-01

    Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of ˜2 m2. The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A, 500 keV D- ion beams for 100 s.

  15. In situ analyses on negative ions in the indium-gallium-zinc oxide sputtering process

    SciTech Connect

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo

    2013-07-01

    The origin of negative ions in the dc magnetron sputtering process using a ceramic indium-gallium-zinc oxide target has been investigated by in situ analyses. The observed negative ions are mainly O{sup -} with energies corresponding to the target voltage, which originates from the target and barely from the reactive gas (O{sub 2}). Dissociation of ZnO{sup -}, GaO{sup -}, ZnO{sub 2}{sup -}, and GaO{sub 2}{sup -} radicals also contributes to the total negative ion flux. Furthermore, we find that some sputtering parameters, such as the type of sputtering gas (Ar or Kr), sputtering power, total gas pressure, and magnetic field strength at the target surface, can be used to control the energy distribution of the O{sup -} ion flux.

  16. Vacuum insulation of the high energy negative ion source for fusion application

    SciTech Connect

    Kojima, A.; Hanada, M.; Inoue, T.; Watanabe, K.; Taniguchi, M.; Kashiwagi, M.; Umeda, N.; Tobari, H.; Hilmi, A.; Kobayashi, S.; Yamano, Y.; Grisham, L. R.

    2012-02-15

    Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of {approx}2 m{sup 2}. The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A, 500 keV D{sup -} ion beams for 100 s.

  17. Negative Ions Induced Processes in Proto-Planetary Atmospheres and ISM

    NASA Astrophysics Data System (ADS)

    Carelli, F.; Sebastianelli, F.; Gianturco, F. A.

    2011-05-01

    In a carbon-rich red giant or in a carbon-rich protoplanetary nebula (PPN) atmosphere, like CRL 618, the major carbon-bearing chemical species that is initially formed is acetylene.Specific chemical reactions, depending on both density and temperature conditions, could then lead to the formation of polycyclic aromatic hydrocarbons (PAHs), large aromatic planar molecules.Some of the chemical networks assume PAHs synthesis in the molecular envelops of C-rich stars, with acetylene being the major carbon source and requiring at the same time particularly dense and slow stellar winds.More in detail, the ionic chemical model involves hydrocarbon ion-neutral acetylene reactions and both hydrogenation and/or electron recombination processes, thereby implicitly accounting for the presence of low-energy electrons that we argue here to play an important role.Having found that one of the suggested intermediate species, the neutral ortho-benzyne molecule, is indeed capable of forming by electron attachment at low energy (1 eV) at least one metastable anionic state, we have consequently analysed the possibility that condensation reactions, leading to PAHs formation in PPN atmospheres, could occur with negative aromatic species such as stabilized anionic ortho-benzyne (o-C6H4-).To account for this task, through accurate quantum dynamical modelling of the initial steps, we find that, once the primary electron attachment on the neutral ortho-benzyne has taken place producing the corresponding metastable negative ion, the evolution of this resonant anionic intermediate in terms of its energy locations and lifetimes suggests the possibility of a radiationless stabilization by a very rapid intramolecular vibrational redistribution (IVR) of the excess energy carried by the attached electron.Currently,always in the low-energy range (0-5 eV), we are studying the formation mechanisms and evolution of metastable anions of both coronene, given its role in the UV extinction processes due to

  18. Lower ionosphere large positive and negative ions are still puzzling: A potential role in ion induced aerosol formation

    NASA Astrophysics Data System (ADS)

    Arnold, Frank

    2016-04-01

    Inspired by greatly improved possibilities in future rocket borne high mass resolution ion mass spectrometry, previous pioneering rocket borne ion-mass spectrometer measurements, made by our MPIK-Heidelberg research group in the lower ionosphere, are revisited and reanalyzed. Here the focus is placed upon puzzling observations of lower ionosphere large positive and large negative ions. These have a role in lower ionosphere free electron removal. They also have a potential role in lower ionosphere aerosol and eventually even cloud formation. Measurements and model simulations are presented.

  19. Electron collisional detachment processes for a 250 keV D/sup -/ ion beam in a partially ionized hydrogen target

    SciTech Connect

    Savas, S.E.

    1980-09-01

    Neutral atom beams with energies above 200 keV may be required for various purposes in magnetic fusion devices following TFTR, JET and MFTF-B. These beams can be produced much more efficiently by electron detachment from negative ion beams than by electron capture by positive ions. We have investigated the efficiency with which such neutral atoms can be produced by electron detachment in partially ionized hydrogen plasma neutralizers.

  20. Optical emission spectroscopy at the large RF driven negative ion test facility ELISE: Instrumental setup and first results

    SciTech Connect

    Wünderlich, D.; Fantz, U.; Franzen, P.; Riedl, R.; Bonomo, F.

    2013-09-15

    One of the main topics to be investigated at the recently launched large (A{sub source}= 1.0 × 0.9 m{sup 2}) ITER relevant RF driven negative ion test facility ELISE (Extraction from a Large Ion Source Experiment) is the connection between the homogeneity of the plasma parameters close to the extraction system and the homogeneity of the extracted negative hydrogen ion beam. While several diagnostics techniques are available for measuring the beam homogeneity, the plasma parameters are determined by optical emission spectroscopy (OES) solely. First OES measurements close to the extraction system show that without magnetic filter field the vertical profile of the plasma emission is more or less symmetric, with maxima of the emission representing the projection of the plasma generation volumes, and a distinct minimum in between. The profile changes with the strength of the magnetic filter field but under all circumstances the plasma emission in ELISE is much more homogeneous compared to the smaller IPP prototype sources. Planned after this successful demonstration of the ELISE OES system is to combine OES with tomography in order to determine locally resolved values for the plasma parameters.

  1. Simulation of space charge compensation in a multibeamlet negative ion beam.

    PubMed

    Sartori, E; Maceina, T J; Veltri, P; Cavenago, M; Serianni, G

    2016-02-01

    Ion beam space charge compensation occurs by cumulating in the beam potential well charges having opposite polarity, usually generated by collisional processes. In this paper we investigate the case of a H(-) ion beam drift, in a bi-dimensional approximation of the NIO1 (Negative Ion Optimization phase 1) negative ion source. H(-) beam ion transport and plasma formation are studied via particle-in-cell simulations. Differential cross sections are sampled to determine the velocity distribution of secondary particles generated by ionization of the residual gas (electrons and slow H2 (+) ions) or by stripping of the beam ions (electrons, H, and H(+)). The simulations include three beamlets of a horizontal section, so that multibeamlet space charge and secondary particle diffusion between separate generation regions are considered, and include a repeller grid biased at various potentials. Results show that after the beam space charge is effectively screened by the secondary plasma in about 3 μs (in agreement with theoretical expectations), a plasma grows across the beamlets with a characteristic time three times longer, and a slight overcompensation of the electric potential is verified as expected in the case of negative ions. PMID:26932089

  2. Kinetic-Energy Distributions of Positive and Negative Ions in DC Townsend Discharges of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Rao, M. V. V. S.; van Brunt, R. J.; Olthoff, J. K.

    1997-10-01

    Ion kinetic-energy distributions (IEDs), mean energies, and relative abundances are measured for CO_2^+, CO^+, O_2^+, O^+, C^+, and O^- ions produced in dc Townsend discharges in pure carbon dioxide. The discharges are generated at electric field-to-gas density ratios (E/N) ranging from 3.5 x 10-18 Vm^2 to 20 x 10-18 Vm^2 (3.5 to 20 kTd). Ions sampled from the discharge through a small orifice in the center of the grounded electrode were energy and mass analyzed by an electrostatic energy analyzer attached to a quadrupole mass spectrometer.(M. V. V. S. Rao, R. J. Van Brunt, and J. K. Olthoff, Phys. Rev. E 54), 5641 (1996) In the present experiments, CO_2^+ was determined to be the dominant positive ion (greater than 85%) at all E/N. The IEDs of CO_2^+, O_2^+, and O^+ are Maxwellian at all E/N, with CO^+ exhibiting non-Maxwellian behavior above 10 kTd, and C^+ exhibiting non-Maxwellian behavior at all E/N. Negative ion fluxes were substantially lower than positive ion fluxes, with O^- being the only detectable negative ion. The IEDs for O^- are Maxwellian at 6 kTd and below. The fact that O^- is the only negative ion indicates that no asymmetric charge transfer exists for O^- in CO_2.

  3. An experimental study of waveguide coupled microwave heating with conventional multicusp negative ion sources

    NASA Astrophysics Data System (ADS)

    Komppula, J.; Kalvas, T.; Koivisto, H.; Laulainen, J.; Tarvainen, O.

    2015-04-01

    Negative ion production with conventional multicusp plasma chambers utilizing 2.45 GHz microwave heating is demonstrated. The experimental results were obtained with the multicusp plasma chambers and extraction systems of the RF-driven RADIS ion source and the filament driven arc discharge ion source LIISA. A waveguide microwave coupling system, which is almost similar to the one used with the SILHI ion source, was used. The results demonstrate that at least one third of negative ion beam obtained with inductive RF-coupling (RADIS) or arc discharge (LIISA) can be achieved with 1 kW of 2.45 GHz microwave power in CW mode without any modification of the plasma chamber. The co-extracted electron to H- ratio and the optimum pressure range were observed to be similar for both heating methods. The behaviour of the plasma implies that the energy transfer from the microwaves to the plasma electrons is mainly an off-resonance process.

  4. Development of a negative ion-based neutral beam injector in Novosibirsk.

    PubMed

    Ivanov, A A; Abdrashitov, G F; Anashin, V V; Belchenko, Yu I; Burdakov, A V; Davydenko, V I; Deichuli, P P; Dimov, G I; Dranichnikov, A N; Kapitonov, V A; Kolmogorov, V V; Kondakov, A A; Sanin, A L; Shikhovtsev, I V; Stupishin, N V; Sorokin, A V; Popov, S S; Tiunov, M A; Belov, V P; Gorbovsky, A I; Kobets, V V; Binderbauer, M; Putvinski, S; Smirnov, A; Sevier, L

    2014-02-01

    A 1000 keV, 5 MW, 1000 s neutral beam injector based on negative ions is being developed in the Budker Institute of Nuclear Physics, Novosibirsk in collaboration with Tri Alpha Energy, Inc. The innovative design of the injector features the spatially separated ion source and an electrostatic accelerator. Plasma or photon neutralizer and energy recuperation of the remaining ion species is employed in the injector to provide an overall energy efficiency of the system as high as 80%. A test stand for the beam acceleration is now under construction. A prototype of the negative ion beam source has been fabricated and installed at the test stand. The prototype ion source is designed to produce 120 keV, 1.5 A beam.

  5. Cs-doped Mo as surface converter for H{sup −}/D{sup −} generation in negative ion sources: First steps and proof of principle

    SciTech Connect

    Schiesko, L. Hopf, C.; Höschen, T.; Meisl, G.; Encke, O.; Franzen, P.; Heinemann, B.; Hopf, C.; Fantz, U.; Cartry, G.; Achkasov, K.

    2015-04-08

    In a proof-of-principle study, molybdenum samples were implanted with a very small dose of Cs in order to test the properties of the compound as a surface converter for negative hydrogen ion production. First results on the properties of Cs doped Mo compounds show a reduction of the work function and a stable H{sup −} yield up to four hours in low density hydrogen plasma. The implanted Cs atoms were stable in the Mo lattice over one year for samples stored in vacuum and not exposed to the plasma. The surface H{sup −} generation mechanisms were identified and a comparison of the negative ion yield with pure Mo showed that the Cs doped Mo sample’s yield was much larger.

  6. Measurement of the positron diffusion constants in polycrystalline molybdenum by the observation of positronium negative ions

    NASA Astrophysics Data System (ADS)

    Suzuki, Takuji; Iida, Simpei; Yamashita, Takashi; Nagashima, Yasuyuki

    2015-06-01

    We have measured the positron diffusion constants in polycrystalline molybdenum by the observation of positronium negative ions (Ps-). The Ps- ions emitted from the sample surface coated with Na were accelerated. The γ-rays from the accelerated Ps- ions were Doppler- shifted and thus the signals of self-annihilation of the Ps- ions were isolated from those of self-annihilation of para-positronium (p-Ps) or pair-annihilation of positrons in the bulk. Clear and reliable values of the diffusion constants have been obtained.

  7. Reduction of friction stress of ethylene glycol by attached hydrogen ions

    PubMed Central

    Li, Jinjin; Zhang, Chenhui; Deng, Mingming; Luo, Jianbin

    2014-01-01

    In the present work, it is shown that the friction stress of ethylene glycol can decrease by an order of magnitude to achieve superlubricity if there are hydrogen ions attached on the friction surfaces. An ultra-low friction coefficient (μ = 0.004) of ethylene glycol between Si3N4 and SiO2 can be obtained with the effect of hydrogen ions. Experimental result indicates that the hydrogen ions adsorbed on the friction surfaces forming a hydration layer and the ethylene glycol in the contact region forming an elastohydrodynamic film are the two indispensable factors for the reduction of friction stress. The mechanism of superlubricity is attributed to the extremely low shear strength of formation of elastohydrodynamic film on the hydration layer. This finding may introduce a new approach to reduce friction coefficient of liquid by attaching hydrogen ions on friction surfaces. PMID:25428584

  8. Thermal cycling and high power density hydrogen ion beam irradiation of tungsten layers on tungsten substrate

    NASA Astrophysics Data System (ADS)

    Airapetov, A. A.; Begrambekov, L. B.; Gretskaya, I. Yu; Grunin, A. V.; Dyachenko, M. Yu; Puntakov, N. A.; Sadovskiy, Ya A.

    2016-09-01

    Tungsten layers with iron impurity were deposited on tungsten substrates modeling re-deposited layers in a fusion device. The samples were tested by thermocycling and hydrogen ion beam tests. Thermocycling revealed globule formation on the surface. The size of the globules depended on iron impurity content in the coating deposited. Pore formation was observed which in some cases lead to exfoliation of the coatings. Hydrogen ion irradiation lead to formation of blisters on the coating and finally its exfoliation.

  9. Experiment and modeling of laser photodetachment of negative ions in helium oxygen barrier discharges

    NASA Astrophysics Data System (ADS)

    Tschiersch, Robert; Nemschokmichal, Sebastian; Meichsner, Jürgen

    2015-09-01

    Helium oxygen discharges operating at atmospheric pressure are of great interest for applications, such as surface treatment of biological samples. Helium as the buffer gas keeps the driving power low, and oxygen serves as the source of radicals. The large electronegativity of oxygen results in the formation of negative ions which in turn have a remarkable influence on the discharge development. To point out this role of negative ions, the change of the discharge behavior after the laser photodetachment of negative ions is measured in a helium oxygen barrier discharge. These measurements reveal a lower breakdown voltage when firing the laser during the pre-phase of the discharge. The reason is the additional pre-ionization by the detached electrons which was proved by an 1D numeric fluid modeling. The next step is the determination of absolute number densities of negative ions by a comparison of the experimental parameter variations with those from the modeling. Furthermore, the actual role of negative ions on the discharge behavior will be emphasized by the modeling.

  10. 100 s extraction of negative ion beams by using actively temperature-controlled plasma grid

    SciTech Connect

    Kojima, A. Hanada, M.; Yoshida, M.; Tobari, H.; Kashiwagi, M.; Umeda, N.; Watanabe, K.; Grisham, L. R.

    2014-02-15

    Long pulse beam extraction with a current density of 120 A/m{sup 2} for 100 s has been achieved with a newly developed plasma grid (PG) for the JT-60SA negative ion source which is designed to produce high power and long pulse beams with a negative ion current of 130 A/m{sup 2} (22 A) and a pulse length of 100 s. The PG temperature is regulated by fluorinated fluids in order to keep the high PG temperature for the cesium-seeded negative ion production. The time constant for temperature controllability of the PG was measured to be below 10 s, which was mainly determined by the heat transfer coefficient of the fluorinated fluid. The measured decay time of the negative ion current extracted from the actively temperature-controlled PG was 430 s which was sufficient for the JT-60SA requirement, and much longer than that by inertial-cooling PG of 60 s. Obtained results of the long pulse capability are utilized to design the full size PG for the JT-60SA negative ion source.

  11. Hydrogen removal from e-beam deposited alumina thin films by oxygen ion beam

    SciTech Connect

    Das, Arijeet Mukharjee, C. Rajiv, K. Bose, Aniruddha Singh, S. D. Rai, S. K.; Ganguli, Tapas; Joshi, S. C.; Deb, S. K.; Phase, D. M.

    2014-04-24

    Hydrogen interstitials and oxygen vacancies defects create energy levels in the band gap of alumina. This limits the application of alumina as a high-k dielectric. A low thermal budget method for removal of hydrogen from alumina is discussed. It is shown that bombardment of alumina films with low energy oxygen ion beam during electron beam evaporation deposition decreases the hydrogen concentration in the film significantly.

  12. Specific interaction between negative atmospheric ions and organic compounds in atmospheric pressure corona discharge ionization mass spectrometry.

    PubMed

    Sekimoto, Kanako; Sakai, Mami; Takayama, Mitsuo

    2012-06-01

    The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O(2)(-), HCO(3)(-), COO(-)(COOH), NO(2)(-), NO(3)(-), and NO(3)(-)(HNO(3)) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion.

  13. Influence of transversal magnetic field on negative ion extraction process in 3D computer simulation of the multi-aperture ion source

    SciTech Connect

    Turek, M.; Sielanko, J.; Franzen, P.; Speth, E.

    2006-01-15

    The negative ion beam extraction from the multi-hole ion source is considered. Results of numerical simulations (based on PIC method) of the influence of transversal magnetic field applied near the extraction grid (filter field), and in the plasma chamber volume (confining field) are presented. The application of confining field results in significantly increased negative ions yield.

  14. Ion and laser microprobes applied to the measurement of corrosion produced hydrogen on a microscopic scale.

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1972-01-01

    Use of an ion microprobe and a laser microprobe to measure concentrations of corrosion-produced hydrogen on a microscopic scale. Hydrogen concentrations of several thousand ppm were measured by both analytical techniques below corroded and fracture surfaces of hot salt stress corroded titanium alloy specimens. This extremely high concentration compares with only about 100 ppm hydrogen determined by standard vacuum fusion chemical analyses of bulk samples. Both the ion and laser microprobes were used to measure hydrogen concentration profiles in stepped intervals to substantial depths below the original corroded and fracture surfaces. For the ion microprobe, the area of local analysis was 22 microns in diameter and for the laser microprobe, the area of local analysis was about 300 microns in diameter. The segregation of hydrogen below fracture surfaces supports a previously proposed theory that corrosion-produced hydrogen is responsible for hot salt stress corrosion embrittlement and cracking of titanium alloys. These advanced analytical techniques suggest great potential for many areas of stress corrosion and hydrogen embrittlement research, quality control, and field inspection of corrosion problems. For example, it appears possible that a contour map of hydrogen distribution at notch roots and crack tips could be quantitatively determined. Such information would be useful in substantiating current theories of stress corrosion and hydrogen embrittlement.

  15. Theoretical studies of o-, m-, and p-benzyne negative ions

    SciTech Connect

    Nash, J.J.; Squires, R.R.

    1996-11-27

    A general theoretical description of `distonic` radical anions is presented, along with an account of an extensive series of ab initio molecular orbital and density functional theory calculations on the negative ions of o-, m- and p-benzyne. The performance of several different computational methods is evaluated with respect to artifactual symmetry-breaking. QCISD(T), CCSD(T), CASPT2N, and DFT(B3LYP) calculations employing double-{zeta} quality basis sets predict that o-, m- and p-benzyne anions all have high-symmetry, delocalized radical anion ground electronic states: {sup 2}B{sub 2} (C{sub 2v}), {sup 2}B{sub 2} (C{sub 2v}), and {sup 2}A{sub g} (D{sub 2h}), respectively. The meta and para isomers also exhibit low-lying, localized radical anion forms with distorted geometries that arise by pseudo Jahn-Teller interactions (vibronic coupling): {sup 2}A`(C{sub s}) for m-benzyne anion and {sup 2}A{sub 1} (C{sub 2v}) for p-benzyne anion. Broken-symmetry wave functions are obtained at symmetrical geometries from MCSCF and CISD calculations for p-benzyne anion, but not for o- and m-benzyne anions. The calculated potential energy surface for in-place distortion of m- and p-benzyne anions are found to be quite flat. An isodesmic reaction approach is used to calculate the electron, proton, and hydrogen atom-binding energies for each of the minimum energy states. Good agreement is achieved between the experimental estimates for these quantities and the calculated values for the lowest-energy anion states. 48 refs., 4 figs., 7 tabs.

  16. Photodissociation and charge transfer dynamics of negative ions studied with femtosecond photoelectron spectroscopy

    SciTech Connect

    Zanni, Martin T.

    1999-12-17

    This dissertation presents studies aimed at understanding the potential energy surfaces and dynamics of isolated negative ions, and the effects of solvent on each. Although negative ions play important roles in atmospheric and solution phase chemistry, to a large extent the ground and excited state potential energy surfaces of gas phase negative ions are poorly characterized, and solvent effects even less well understood. In an effort to fill this gap, the author's coworkers and the author have developed a new technique, anion femtosecond photoelectron spectroscopy, and applied it to gas phase photodissociation and charge transfer processes. Studies are presented that (1) characterize the ground and excited states of isolated and clustered anions, (2) monitor the photodissociation dynamics of isolated and clustered anions, and (3) explore the charge-transfer-to-solvent states of atomic iodide clustered with polar and non-polar solvents.

  17. Surface treatment of silicone rubber by carbon negative-ion implantation for nerve regeneration

    NASA Astrophysics Data System (ADS)

    Tsuji, Hiroshi; Izukawa, Masayoshi; Ikeguchi, Ryosuke; Kakinoki, Ryosuke; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo

    2004-07-01

    Surface treatment of silicone rubber by carbon negative ion-implantation was investigated for nerve regeneration by "tubulation". Silicone rubber had its surface property altered to be more hydrophilic by carbon negative-ion implantation. The extracellular matrices of proteins in culture medium adsorbed on the implanted surface rather than unimplanted ones. These improvements in wettability and adsorption properties of proteins were respected to contribute to the regeneration of a nerve-lacking system. An in vivo regeneration test of rat sciatic nerves with silicone-rubber tubes was performed. Using a tube in which the inner surface was implanted with carbon negative ions, the sciatic nerve was regenerated through the inter-stump gap of 15 mm between the proximal and distal nerve stumps and electrical stimulation was transported through the regenerated nerve. Thus, the nerve system was recovered. However, with the unimplanted tube, the nerve was not regenerated at all.

  18. Theory and observation of a dynamically evolving negative ion plasma. [in F region

    NASA Technical Reports Server (NTRS)

    Mendillo, M.; Forbes, J.

    1982-01-01

    The study described here examines the full range of negative-ion chemistry in the upper ionosphere by using current reaction rate data to investigate the many chemical paths SF6-type injections might take in an F region environment. Special attention is given to the conditions required to create heavy negative ions that persist long enough to affect the dynamical properties of the F region. The ambipolar diffusion characteristics of a three-component plasma are described, and estimates are given of the incoherent scatter spectra obtained from such a plasma. Model calculations using a first-order chemical code are defined and tested in order to investigate the actual types of negative-ion plasma capable of being created under nighttime conditions.

  19. Dust acoustic solitary wave with variable dust charge: Role of negative ions

    SciTech Connect

    Ghosh, Samiran

    2005-09-15

    The role of negative ions on small but finite amplitude dust acoustic solitary wave including the effects of high and low charging rates of dust grains compared to the dust oscillation frequency in electronegative dusty plasma is investigated. In the case of high charging rate, the solitary wave is governed by Korteweg-de Vries (KdV) equation, but in the case of low charging rate, it is governed by KdV equation with a linear damping term. Numerical investigations reveal that in both cases dust acoustic soliton sharpens (flatens) and soliton width decreases (increases) with the increase of negative-ion number density (temperature). Also, the negative ions reduce the damping rate.

  20. Negative deuterium ions for tandem mirror next step and tandem mirror reactors

    SciTech Connect

    Hamilton, G.W.

    1980-09-25

    Recent designs for mirror fusion reactors with good power balance include ambipolar potential plugs to reduce end losses and thermal barriers to maintain a difference in electron temperature between the large-volume central cell plasma and the confining end plugs. These designs led to several new requirements for D/sup 0/ neutral beams derived from negative ions at energies of 150 to 200 keV and possibly higher. Such beams are required for injection of fat ions into the plugs and the barrier and for charge-exchange pumping of thermal ions diffusing into the barrier. Negative ions are preferred for these purposes because of their relatively high efficiency of neutralization and their high purity of single-energy D/sup -/. Examples of injector designs for Tandem Mirror Next Step (TMNS) and Tandem Mirror Reactors (TMR) are presented.

  1. Angle-resolved DIET of negative ions from halogenated molecules on Ru(0001)

    NASA Astrophysics Data System (ADS)

    Nair, L.; Sack, N. J.; Madey, T. E.

    1995-06-01

    We present data on the electron stimulated desorption (ESD) of negative ions from PF 3 and CCl 4 adsorbed on Ru(0001) at 100 K. We use a two-dimensional digital ESDIAD detector with time-of-flight capability which allows mass and angle resolved ion detection. We find F - and F 2- to desorb from PF 3, yielding hexagonal ESDIAD patterns, and Cl - and Cl 2- from CCl 4, desorbing in a broad normal emission. The ratio of F 2- to F - and of Cl 2- to Cl - is more than a factor 10 higher than in electron induced gas phase dissociation. We compare the negative ion yields to those of positive ions.

  2. Potential formation in a collisionless plasma produced in an open magnetic field in presence of volume negative ion source

    SciTech Connect

    Phukan, Ananya Goswami, K. S.; Bhuyan, P. J.

    2014-08-15

    The electric potential near a wall for a multi-species plasma with volume produced negative ions in presence of axially varying magnetic field is studied following an analytical-numerical approach. A constant negative ion source is assumed throughout the plasma volume, along with finite temperature positive ions and Boltzmann electrons. The particles are assumed to be guided by an open magnetic field that has its maximum at the centre, and field strength decreasing towards the walls. The one dimensional (1D) Poisson equation is derived using an analytical approach, and then solved numerically to study the potential profiles. Effect of (a) negative ion production rate, (b) magnetic field profile, and (c) negative ion temperature on the potential profile has been investigated. A potential peak appears near the wall when the negative ion temperature and density are sufficiently high. Also, the presence of negative ions further decreases the potential in the plasma region for a finite Debye Length (λ{sub D})

  3. The effects of negative air ions on various physiological functions during work in a hot environment

    NASA Astrophysics Data System (ADS)

    Inbar, O.; Rotstein, A.; Dlin, R.; Dotan, R.; Sulman, F. G.

    1982-06-01

    The effects of negative air-ions on human physical performance has been investigated. Twenty-one healthy males, 20 25 years old (X=23.6±2.6) were exposed to two 180-min rest and exercise sessions two weeks apart. The subjects were randomly assigned into either an experimental group (n=12) or to a control group (n=9). The experimental group performed the first session in neutral air conditions and the second one in air containing 1.36 to 1.90×105 negative air ions and 1.40 to 1.66×102 positive air ions/ml. The control group performed both sessions under neutral air conditions. All sessions were held at Ta=40±1‡C and 25±5% RH. Each session included one hour of resting under the respective ionization conditions, followed by 3 30-min cycle ergometer work bouts, separated by 7-min rest periods. The mechanical work-load during the bicycle exercise was 1.64±0.6 W/kg BW. The experimental group showed a significant reduction with negative air-ions in heart rate (HR), in rectal temperature, and in the rating of perceived exertion (RPE), all when compared with their own neutral session. The control group showed no significant changes between the first and the second exposure. Although not statistically significant, being exposed to negative air-ions seems also to reduce total sweat rate and minute ventilation (VE), and to increase O2 pulse. It is suggested that under the conditions of this study negative air ions can improve various cardiovascular and thermoregulatory functions as well as subjective feelings during physical effort. It is felt that such positive influences may be augmented by increasing the exposure time to negative ionized air and/or prolonging the stressful conditions.

  4. Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry.

    PubMed

    Muftakhov; Vasil'ev; Mazunov

    1999-06-01

    Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd. PMID:10407285

  5. Method and system for producing hydrogen using sodium ion separation membranes

    SciTech Connect

    Bingham, Dennis N; Klingler, Kerry M; Turner, Terry D; Wilding, Bruce M; Frost, Lyman

    2013-05-21

    A method of producing hydrogen from sodium hydroxide and water is disclosed. The method comprises separating sodium from a first aqueous sodium hydroxide stream in a sodium ion separator, feeding the sodium produced in the sodium ion separator to a sodium reactor, reacting the sodium in the sodium reactor with water, and producing a second aqueous sodium hydroxide stream and hydrogen. The method may also comprise reusing the second aqueous sodium hydroxide stream by combining the second aqueous sodium hydroxide stream with the first aqueous sodium hydroxide stream. A system of producing hydrogen is also disclosed.

  6. The negative effects of hydrogenated trans fats and what to do about them.

    PubMed

    Kummerow, Fred A

    2009-08-01

    Partially hydrogenated vegetable oils have been in the American diet since 1900. More than 50 years ago they were found to contain trans fatty acids that were different from natural fatty acids in plant oils and in animal fat. There was growing evidence that the consumption of trans fats have negative health effects, including increasing plasma lipid levels. In 2003, the Food and Drug Administration (FDA) ruled that the amount of trans fat in a food item must be stated on the label after January 1, 2006; food items could be labeled 0% trans if they contain less than 0.5g/serving. Since the initial ruling, it is now known that the fatty acids in partially hydrogenated vegetable oil are 14 cis and trans isomers of octadecenoic and octadecadienoic acids that are formed during hydrogenation. They cause inflammation and calcification of arterial cells: known risk factors for coronary heart disease (CHD). They inhibit cyclooxygenase, an enzyme required for the conversion of arachidonic acid to prostacyclin, necessary for the regulation of blood flow. There have been several reformulations of hydrogenated fat containing varying amounts of trans fatty acids and linoleic acid, an essential fatty acid that is converted to arachidonic acid. Epidemiological data suggest that when trans fat percentages go up and linoleic acid percentages go down, death rates rise; when trans goes down, death rates go down. In spite of the harmful effects of trans fats, the FDA allows it in the food supply as long as the amount in a food item is declared on the label. Trans fat should be banned from the food supply.

  7. Comparative analysis of continuous-wave surface-plasma negative ion sources with various discharge geometry

    SciTech Connect

    Belchenko, Yu; Sanin, A.; Sotnikov, O.

    2014-02-15

    Negative ion extraction from continuous-wave (CW) magnetron and semiplanotron discharges was studied and it was compared with that for the source with Penning electrode geometry. The CW negative ion beam up current to 13 mA was extracted from the magnetron source with emission aperture of 3.5 mm in diameter, while the beam with current up to 8 mA was obtained from the semiplanotron source modification. Characteristics of CW magnetron and semiplanotron sources are presented and analyzed.

  8. Characteristics of plasma grid bias in large-scaled negative ion source

    SciTech Connect

    Kisaki, M.; Tsumori, K.; Ikeda, K.; Nakano, H.; Osakabe, M.; Nagaoka, K.; Takeiri, Y.; Kaneko, O.

    2014-02-15

    The electron density was measured at various bias voltages to understand how the plasma grid bias affects the electron near the plasma grid in large-scaled negative ion sources. It was found that the response of the electron to the bias voltage changes depending on negative ion production processes. The electron density remarkably decreases with increasing the bias voltage in the pure-volume plasma. On the other hand, the electron density depends on the bias voltage weakly in the Cs-seeded plasma. In addition, it was observed that the response of the co-extracted electron current to the bias voltage has similar trend to that of the electron density.

  9. Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions

    SciTech Connect

    Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.

    2006-11-15

    The effects of charging-delay and negative ions on nonlinear dust acoustic waves are investigated. It has been found that the charging-delay induced anomalous dissipation causes generation of dust acoustic collisionless shock waves in an electronegative dusty plasma. The small but finite amplitude wave is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay induced dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)

  10. Resolving Interferences in Negative Mode Ion Mobility Spectrometry Using Selective Reactant Ion Chemistry

    SciTech Connect

    Daum, Keith Alvin; Atkinson, David Alan; Ewing, Robert Gordon; Knighton, W. B.; Grimsrud, E. P

    2001-04-01

    During the investigation of the degradation products of 2,4,6-trinitrotoluene (TNT) using ion mobility spectrometry (IMS), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (DCP) were found to have IMS responses which overlapped those of the TNT degradation products. It was observed that the Cl- reactant ion chemistry, often used for explosives analysis, was not always successful in resolving peak overlap of analytes and interferents. It is shown here that resolution of the analytes and interferences can sometimes be achieved using only air for the formation of reactant ions, at other times through the use of Br- as an alternative to Cl- for producing reactant ions, and also through the promotion of adduct stability by lowering the IMS temperature.

  11. Method and apparatus for providing negative ions of actinide-metal hexafluorides

    DOEpatents

    Compton, Robert N.; Reinhardt, Paul W.; Garrett, William R.

    1978-01-01

    This invention relates to a novel method and a novel generator, or source, for providing gaseous negative ions of selected metal hexafluorides. The method is summarized as follows: in an evacuated zone, reacting gaseous fluorine with an actinide-metal body selected from the group consisting of uranium, plutonium, neptunium, and americium to convert at least part of the metal to the hexafluoride state, thus producing gaseous negatively charged metal-hexafluoride ions in the evacuated zone, and applying an electric field to the zone to remove the ions therefrom. The ion source comprises a chamber defining a reaction zone; means for evacuating the zone; an actinide-metal body in the zone, the metal being uranium, plutonium, neptunium, or americium; means for contacting the body with gaseous fluorine to convert at least a part thereof to the hexafluoride state; and means for applying an electric field to the evacuated zone to extract gaseous, negatively charged metal-hexafluoride ions therefrom. The invention provides unique advantages over conventional surface-ionization techniques for producing such ions.

  12. The behaviour of negative oxygen ions in the afterglow of a reactive HiPIMS discharge

    NASA Astrophysics Data System (ADS)

    Bowes, M.; Bradley, J. W.

    2014-07-01

    Using a single Langmuir probe, the temporal evolution of the oxygen negative ion, n-, and electron, ne, densities in the afterglow of a reactive HiPIMS discharge operating in argon-oxygen gas mixtures have been determined. The magnetron was equipped with a titanium target and operated in ‘poisoned’ mode at a frequency of 100 Hz with a pulse width of 100 µs for a range of oxygen partial pressures, {p_{O_{2}}}/{p_{total}} = 0.0{{-}}0.5 . In the initial afterglow, the density of the principle negative ion in the discharge (O-) was of the order of 1016 m-3 for all conditions. The O- concentration was found to decay slowly with characteristic decay times between 585 µs and 1.2 ms over the oxygen partial pressure range. Electron densities were observed to fall more rapidly, resulting in long-lived highly electronegative afterglow plasmas where the ratio, α = n-/ne, was found to reach values up to 672 (±100) for the highest O2 partial pressure. By comparing results to a simple plasma-chemical model, we speculate that with increased {p_{O_{2}}}/{p_{total}} ratio, more O- ions are formed in the afterglow via dissociative electron attachment to highly excited metastable oxygen molecules, with the latter being formed during the active phase of the discharge. After approximately 2.5 ms into the off-time, the afterglow degenerates into an ion-ion plasma and negative ions are free to impinge upon the chamber walls and grounded substrates with flux densities of the order of 1018 m-2 s-1, which is around 10% of the positive ion flux measured during the on-time. This illustrates the potential importance of the long afterglow in reactive HiPIMS, which can act as a steady source of low energy O- ions to a growing thin film at the substrate during periods of reduced positive ion bombardment.

  13. Femtosecond Hydrogen Bond Dynamics of Bulk-like and Bound Water at Positively and Negatively Charged Lipid Interfaces Revealed by 2D HD-VSFG Spectroscopy.

    PubMed

    Singh, Prashant Chandra; Inoue, Ken-Ichi; Nihonyanagi, Satoshi; Yamaguchi, Shoichi; Tahara, Tahei

    2016-08-26

    Interfacial water in the vicinity of lipids plays an important role in many biological processes, such as drug delivery, ion transportation, and lipid fusion. Hence, molecular-level elucidation of the properties of water at lipid interfaces is of the utmost importance. We report the two-dimensional heterodyne-detected vibrational sum frequency generation (2D HD-VSFG) study of the OH stretch of HOD at charged lipid interfaces, which shows that the hydrogen bond dynamics of interfacial water differ drastically, depending on the lipids. The data indicate that the spectral diffusion of the OH stretch at a positively charged lipid interface is dominated by the ultrafast (<∼100 fs) component, followed by the minor sub-picosecond slow dynamics, while the dynamics at a negatively charged lipid interface exhibit sub-picosecond dynamics almost exclusively, implying that fast hydrogen bond fluctuation is prohibited. These results reveal that the ultrafast hydrogen bond dynamics at the positively charged lipid-water interface are attributable to the bulk-like property of interfacial water, whereas the slow dynamics at the negatively charged lipid interface are due to bound water, which is hydrogen-bonded to the hydrophilic head group. PMID:27482947

  14. Complete positive ion, electron, and ram negative ion measurements near Comet Halley (COPERNIC) plasma experiment for the European Giotto Mission

    NASA Technical Reports Server (NTRS)

    Lin, Robert P.

    1988-01-01

    Participation of U.S. scientists on the COPERNIC (COmplete Positive ions, Electrons and Ram Negative Ion measurements near Comet Halley) plasma experiment on the Giotto mission is described. The experiment consisted of two detectors: the EESA (electron electrostatic analyzer) which provided three-dimensional measurements of the distribution of electrons from 10 eV to 30 keV, and the PICCA (positive ion cluster composition analyzer) which provided mass analysis of positively charged cold cometary ions from mass 10 to 210 amu. In addition, a small 3 deg wide sector of the EESA looking in the ram direction was devoted to the detection of negatively charged cold cometary ions. Both detectors operated perfectly up to near closest approach (approx. 600 km) to Halley, but impacts of dust particles and neutral gas on the spacecraft contaminated parts of the data during the last few minutes. Although no flight hardware was fabricated in the U.S., The U.S. made very significant contributions to the hardware design, ground support equipment (GSE) design and fabrication, and flight and data reduction software required for the experiment, and also participated fully in the data reduction and analysis, and theoretical modeling and interpretation. Cometary data analysis is presented.

  15. Effect of irradiation by argon ions on hydrogen transport through the surface oxide layer of zirconium

    NASA Astrophysics Data System (ADS)

    Evsin, A. E.; Begrambekov, L. B.; Gumarov, A. I.; Kashapov, N. F.; Luchkin, A. G.; Vakhitov, I. R.; Yanilkin, I. V.; Tagirov, L. R.

    2016-09-01

    Effect of zirconium irradiation by 1 keV Ar+ ions on hydrogen transport through the surface oxide layer is studied. It is shown that deuterium trapping under subsequent irradiation of the Ar-treated sample by deuterium atoms of thermal energies in D2 + 30at.% O2 gas mixture is 2 times less than trapping in the untreated sample. Besides, irradiation of the untreated sample by D-atoms provokes desorption of ≈25% of hydrogen contained therein, whereas hydrogen desorption from the ion-treated zirconium surface does not occur. It is proposed that oxygen depletion of the surface oxide layer, caused by ion bombardment, is a reason of mitigation of the hydrogen transport through this layer in both directions.

  16. The production and destruction of negative ions. Progress report, September 1, 1992--August 31, 1993

    SciTech Connect

    Pegg, D.J.

    1993-04-01

    Single photon absorption-single electron detachment from few-electron atomic negative ions was studied. A crossed beam apparatus is being used to perform energy- and angle-resolved photoelectron spectroscopic measurements following photodetachment. Forward-directed electrons were collected and energy analyzed. The kinetic energies and yields of the photoelectrons were obtained by fitting the spectral peaks to Gaussian functions. Electron affinities, asymmetry parameters and cross sections are determined from these measurements. A ratio method in which the cross section for the ion of interest is measured relative to that of a reference ion was used. The study of the photodetachment of Li{sup {minus}} was completed, and attention has turned to the photodetachment of the stable ion B{sup {minus}} and the metastable ion Be{sup {minus}}.

  17. Recent progress of high-power negative ion beam development for fusion plasma heating

    NASA Astrophysics Data System (ADS)

    Watanabe, Kazuhiro; Akino, Noboru; Aoyagi, Tetsuo; Ebisawa, Noboru; Fujiwara, Yukio; Honda, Atsusi; Inoue, Takashi; Itoh, Takao; Kawai, Mikito; Kazawa, Minoru; Koizumi, Junichi; Kuriyama, Masaaki; Miyamoto, Kenji; Miyamoto, Naoki; Mogaki, Kazuhiko; Ohara, Yoshihiro; Ohga, Tokumichi; Okumura, Yoshikazu; Oohara, Hiroshi; Ohshima, Katsumi; Satoh, Fujio; Shimizu, Kazuhiko; Takahashi, Syunji; Usami, Hirotsugu; Usui, Katsutomi; Yamamoto, Masahiro; Yamazaki, Takeshi

    1997-06-01

    A negative-ion-based neutral beam injector (N-NBI) has been constructed for JT-60U. The N-NBI is designed to inject 500 keV, 10 MW neutral beams using two ion sources, each producing a 500 keV, 22 A D - ion beam. In the preliminary experiment using one ion source, a D - ion beam of 13.5 A has been successfully accelerated with an energy of 400 keV (5.4 MW) for 0.12 s at an operating pressure of 0.22 Pa. This is the highest D - beam current and power in the world. Co-extracted electron current was effectively suppressed to the ratio of Ie/ ID - < 1. The highest energy beam of 460 keV, 2.4 A, 0.44 s has also been obtained. To realize 1 MeV class NBI system for ITER (International Thermonuclear Experimental Reactor), demonstration of ampere class negative ion beam acceleration up to 1 MeV is an important mile stone. To achieve the mile stone, a prototype accelerator and a 1 MV, 1 A test facility called MeV Test Facility (MTF) were constructed. Up to now, an H - ion beam was accelerated up to the energy of 805 keV with an acceleration drain current of 150 mA for 1 s in a five stage electrostatic multi-aperture accelerator.

  18. Energy-loss and straggling of hydrogen and helium ions in selenium

    NASA Astrophysics Data System (ADS)

    Conradie, J.; Lombaard, J.; Friedland, E.

    1983-01-01

    Using a transmission technique, the energy-loss and straggling of protons, deuterons and helium ions in Se were measured in the energy range between 0.3 and 2.5 MeV. The experimental stopping powers of the various ions are the same as the semiempirical values of Andersen and Ziegler, except in the vicinity of the stopping power maximum. The reduced straggling for the helium and hydrogen ions is energy independent above 0.25 MeV/amu with the helium values the same as predicted by Bohr but the hydrogen values are somewhat lower.

  19. Ultrafast electronic motion in hydrogen molecular ions induced by a high power intense laser

    NASA Astrophysics Data System (ADS)

    Mineo, H.; Teranishi, Y.; Chao, S. D.; Lin, S. H.

    2010-10-01

    In this Letter we report a method for controlling electronic localization in a molecular ion, on an attosecond time scale, using a high-intensity laser, based on two different excitation mechanisms. One takes place during ionization, and the other takes place sequentially, following ionization. The electronic excited states of the hydrogen molecular ion are created during ionization by taking the configuration interaction mixing of neutral molecules into account. We detect the ultrafast oscillatory electronic motion between two atoms in a hydrogen molecular ion occurring due to the creation of excited states during the course of ionization.

  20. Cancellation of the ion deflection due to electron-suppression magnetic field in a negative-ion accelerator

    SciTech Connect

    Chitarin, G.; Agostinetti, P.; Aprile, D.; Marconato, N.; Veltri, P.

    2014-02-15

    A new magnetic configuration is proposed for the suppression of co-extracted electrons in a negative-ion accelerator. This configuration is produced by an arrangement of permanent magnets embedded in one accelerator grid and creates an asymmetric local magnetic field on the upstream and downstream sides of this grid. Thanks to the “concentration” of the magnetic field on the upstream side of the grid, the resulting deflection of the ions due to magnetic field can be “intrinsically” cancelled by calibrating the configuration of permanent magnets. At the same time, the suppression of co-extracted electrons can be improved.

  1. Rovibrational molecular populations, atoms, and negative ions in H/sub 2/ and D/sub 2/ magnetic multicusp discharges

    SciTech Connect

    Pealat, M.; Taran, J.E.; Bacal, M.; Hillion, F.

    1985-06-01

    Coherent anti-Stokes Raman scattering is applied to the study of rovibrational populations in magnetic multicusp H/sub 2/ and D/sub 2/ discharges. This subject is of interest to negative hydrogen ion formation by volume plasma processes. The populations of high-lying rotational states (J>5) in the vibrational levels v = 0, 1, and 2 are found to be significantly higher than expected from the Boltzmann law. In H/sub 2/ the net populations of the first four vibrational levels follow approximately the Boltzmann law, with the vibrational temperature of 2390 K (in a 90 V-10 A discharge at 55 ..mu..bar). In similar discharge conditions, the population of the state v = 3 in D/sub 2/ is higher than expected from the Boltzmann law. In the presence of the discharge a deficiency in H/sub 2/ and D/sub 2/ molecule density was observed and was attributed to the possible presence of H and D atoms. This was verified by an independent measurement of the atomic fraction and temperature. The density of negative ions, measured by the photodetachment technique, is also reported.

  2. Ion aggregation in high salt solutions. IV. Graph-theoretical analyses of ion aggregate structure and water hydrogen bonding network

    NASA Astrophysics Data System (ADS)

    Choi, Jun-Ho; Cho, Minhaeng

    2015-09-01

    Ions in high salt solutions form a variety of ion aggregates, from ion pairs to clusters and networks. Their influences on water hydrogen bonding (H-bonding) network structures have long been of great interest. Recently, we have shown that the morphological structures of ion aggregates can be analyzed by using a spectral graph analysis theory, where each ion cluster or ion network is represented by a properly defined graph with edges and vertices. Here, to further examine the network properties of ion aggregates and water H-bonding networks in high salt solutions, we consider a few representative graph-theoretical descriptors: clustering coefficient, minimum path length, global efficiency, and degree distribution of ion aggregates. From the molecular dynamics trajectories, these graph theoretical properties of ion aggregates and water structures in NaCl and kosmotropic solutions are calculated and shown to be strongly dependent on the two types of ion aggregate structures, i.e., ion cluster and ion network. Ion clusters in high NaCl solutions exhibit typical behaviors of scale free network. The corresponding graph theoretical properties of ion networks in high KSCN solutions are notably different from those of NaCl ion clusters and furthermore they are very similar to those of water hydrogen-bonding network. The present graph-theoretical analysis results indicate that the high solubility limits of KSCN and other ion-network-forming salts might originate from their ability to form a large scale morphological network that can be intertwined with co-existing water H-bonding network. Furthermore, it is shown that the graph-theoretical properties of water H-bonding network structures do not strongly depend on the nature of dissolved ions nor on the morphological structures of ion aggregates, indicating that water's H-bonding interaction and network-forming capability are highly robust. We anticipate that the present graph-theoretical analysis results of high salt

  3. Ion aggregation in high salt solutions. IV. Graph-theoretical analyses of ion aggregate structure and water hydrogen bonding network.

    PubMed

    Choi, Jun-Ho; Cho, Minhaeng

    2015-09-14

    Ions in high salt solutions form a variety of ion aggregates, from ion pairs to clusters and networks. Their influences on water hydrogen bonding (H-bonding) network structures have long been of great interest. Recently, we have shown that the morphological structures of ion aggregates can be analyzed by using a spectral graph analysis theory, where each ion cluster or ion network is represented by a properly defined graph with edges and vertices. Here, to further examine the network properties of ion aggregates and water H-bonding networks in high salt solutions, we consider a few representative graph-theoretical descriptors: clustering coefficient, minimum path length, global efficiency, and degree distribution of ion aggregates. From the molecular dynamics trajectories, these graph theoretical properties of ion aggregates and water structures in NaCl and kosmotropic solutions are calculated and shown to be strongly dependent on the two types of ion aggregate structures, i.e., ion cluster and ion network. Ion clusters in high NaCl solutions exhibit typical behaviors of scale free network. The corresponding graph theoretical properties of ion networks in high KSCN solutions are notably different from those of NaCl ion clusters and furthermore they are very similar to those of water hydrogen-bonding network. The present graph-theoretical analysis results indicate that the high solubility limits of KSCN and other ion-network-forming salts might originate from their ability to form a large scale morphological network that can be intertwined with co-existing water H-bonding network. Furthermore, it is shown that the graph-theoretical properties of water H-bonding network structures do not strongly depend on the nature of dissolved ions nor on the morphological structures of ion aggregates, indicating that water's H-bonding interaction and network-forming capability are highly robust. We anticipate that the present graph-theoretical analysis results of high salt

  4. Electrostatic energy analyzer measurements of low energy zirconium beam parameters in a plasma sputter-type negative ion source.

    PubMed

    Malapit, Giovanni M; Mahinay, Christian Lorenz S; Poral, Matthew D; Ramos, Henry J

    2012-02-01

    A plasma sputter-type negative ion source is utilized to produce and detect negative Zr ions with energies between 150 and 450 eV via a retarding potential-type electrostatic energy analyzer. Traditional and modified semi-cylindrical Faraday cups (FC) inside the analyzer are employed to sample negative Zr ions and measure corresponding ion currents. The traditional FC registered indistinct ion current readings which are attributed to backscattering of ions and secondary electron emissions. The modified Faraday cup with biased repeller guard ring, cut out these signal distortions leaving only ringings as issues which are theoretically compensated by fitting a sigmoidal function into the data. The mean energy and energy spread are calculated using the ion current versus retarding potential data while the beam width values are determined from the data of the transverse measurement of ion current. The most energetic negative Zr ions yield tighter energy spread at 4.11 eV compared to the least energetic negative Zr ions at 4.79 eV. The smallest calculated beam width is 1.04 cm for the negative Zr ions with the highest mean energy indicating a more focused beam in contrast to the less energetic negative Zr ions due to space charge forces.

  5. Electrostatic energy analyzer measurements of low energy zirconium beam parameters in a plasma sputter-type negative ion source

    SciTech Connect

    Malapit, Giovanni M.; Mahinay, Christian Lorenz S.; Poral, Matthew D.; Ramos, Henry J.

    2012-02-15

    A plasma sputter-type negative ion source is utilized to produce and detect negative Zr ions with energies between 150 and 450 eV via a retarding potential-type electrostatic energy analyzer. Traditional and modified semi-cylindrical Faraday cups (FC) inside the analyzer are employed to sample negative Zr ions and measure corresponding ion currents. The traditional FC registered indistinct ion current readings which are attributed to backscattering of ions and secondary electron emissions. The modified Faraday cup with biased repeller guard ring, cut out these signal distortions leaving only ringings as issues which are theoretically compensated by fitting a sigmoidal function into the data. The mean energy and energy spread are calculated using the ion current versus retarding potential data while the beam width values are determined from the data of the transverse measurement of ion current. The most energetic negative Zr ions yield tighter energy spread at 4.11 eV compared to the least energetic negative Zr ions at 4.79 eV. The smallest calculated beam width is 1.04 cm for the negative Zr ions with the highest mean energy indicating a more focused beam in contrast to the less energetic negative Zr ions due to space charge forces.

  6. Energy-loss and straggling of hydrogen and helium ions in silver

    NASA Astrophysics Data System (ADS)

    Lombaard, J.; Conradie, J.; Friedland, E.

    1983-10-01

    Energy-loss and straggling of protons, deuterons and 4He ions in silver were measured in the energy range between 0.14 MeV and 2.6 MeV. For energies between 0.25 and 0.60 MeV/amu the stopping powers of the hydrogen ions in silver are up to 10% lower than the semi-empirical values of Andersen and Ziegler. Better agreement is obtained with the shell-correction fit for energies above 0.6 MeV/amu. In the case of the helium ions the measured values are between 8% to 13% lower than the semi-empirical values of Ziegler. The reduced straggling for the 4He and hydrogen ions is energy independent above 0.3 MeV/amu with the He values the same as predicted by the Bohr estimate but the hydrogen values are about 15% lower.

  7. In situ spectroscopic ellipsometry studies of hydrogen ion bombardment of crystalline silicon

    SciTech Connect

    Hu, Y.Z.; Li, M.; Conrad, K.; Andres, J.W.; Irene, E.A.; Denker, M.; Ray, M.; McGuire, G.

    1992-05-01

    Hydrogen-bombardment induced damage in single crystal silicon as a function of the substrate temperature, ion energy, and ion dose was studied using in situ spectroscopic ellipsometry over the photon energy range 2.0-5.5 eV under high vacuum conditions. The incident hydrogen ion energies were 300 and 1000 eV, and the doses were 10{sup 15}-10{sup 18} ions/cm{sup 2}. In situ spectroscopic ellipsometry results showed that the damage layer thicknesses for the samples bombarded at elevated temperatures are smaller than for samples bombarded at room temperature and subsequently annealed at the same elevated temperature. The diffusion coefficient for hydrogen in silicon of 6 x 10{sup {minus}15} cm{sup {minus}2}/s was obtained from the in situ spectroscopic ellipsometry data. 40 refs., 11 figs., 1 tab.

  8. Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency.

    PubMed

    Hanada, M; Kojima, A; Tobari, H; Nishikiori, R; Hiratsuka, J; Kashiwagi, M; Umeda, N; Yoshida, M; Ichikawa, M; Watanabe, K; Yamano, Y; Grisham, L R

    2016-02-01

    In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications. PMID:26932050

  9. Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency.

    PubMed

    Hanada, M; Kojima, A; Tobari, H; Nishikiori, R; Hiratsuka, J; Kashiwagi, M; Umeda, N; Yoshida, M; Ichikawa, M; Watanabe, K; Yamano, Y; Grisham, L R

    2016-02-01

    In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications.

  10. Polymerization of tobacco mosaic virus protein without and with hydrogen ion binding.

    PubMed

    Shalaby, R A; Lauffer, M A

    1983-05-01

    When tobacco mosaic virus (TMV) protein is polymerized at pH values above 7 in unbuffered solutions, either by raising temperature at constant ionic strength or by increasing ionic strength at constant temperature, a 20 S component is formed having bound only the very small amount of H+ ion supplied by the unpolymerized protein. When hydrogen ion is added by titration during polymerization so as to keep pH constant, as would occur automatically if a buffer were present, a 20 S component is formed with one H+ ion bound each for half of the subunits. Thus, a 20 S form with and a 20 S form without bound H+ ion exist. Furthermore, the 20 S form without bound H+ ion binds H+ ion when supplied by titration to produce a 20 S form with the same amount of bound H+ ion as when H+ ion is supplied during the polymerization.

  11. Landau damping effects on dust-acoustic solitary waves in a dusty negative-ion plasma

    SciTech Connect

    Barman, Arnab; Misra, A. P. E-mail: apmisra@gmail.com

    2014-07-15

    The nonlinear theory of dust-acoustic waves (DAWs) with Landau damping is studied in an unmagnetized dusty negative-ion plasma in the extreme conditions when the free electrons are absent. The cold massive charged dusts are described by fluid equations, whereas the two-species of ions (positive and negative) are described by the kinetic Vlasov equations. A Korteweg-de Vries (KdV) equation with Landau damping, governing the dynamics of weakly nonlinear and weakly dispersive DAWs, is derived following Ott and Sudan [Phys. Fluids 12, 2388 (1969)]. It is shown that for some typical laboratory and space plasmas, the Landau damping (and the nonlinear) effects are more pronounced than the finite Debye length (dispersive) effects for which the KdV soliton theory is not applicable to DAWs in dusty pair-ion plasmas. The properties of the linear phase velocity, solitary wave amplitudes (in presence and absence of the Landau damping) as well as the Landau damping rate are studied with the effects of the positive ion to dust density ratio (μ{sub pd}) as well as the ratios of positive to negative ion temperatures (σ) and masses (m)

  12. Estimation of Protein Absorption on Polymer Material by Carbon-Negative Ion Implantation

    NASA Astrophysics Data System (ADS)

    Yamada, Tetsuya; Tsuji, Hiroshi; Hattori, Mitsutaka; Sommani, Piyanuch; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo

    Selective cell attachment on carbon-negative-ion implanted region of polystyrene was already reported by the authors. However, the selectivity and adhesion strength in the cell pattering were partially insufficient. The adhesive proteins called extracellular matrix (ECM), in general, intervene between cell and substrate surface in the cell attachment on the solid surface. Therefore, we considered to obtain clearer selective cell attachment with tighter binding strength on the implanted region of polystyrene when these adhesive proteins precedently adsorbed on the implanted region of polystyrene. In this paper, we have investigated adsorption properties of three kinds of adhesive proteins (gelatin, fibronectin, laminin) and cell attachment properties on precedent protein adsorbed surface of polystyrene modified by carbon negative-ion implantation. Carbon negative ions were implanted into polystyrene at energy of 10 keV with dose in a range of 1×1014~1×1016 ions/cm2. After implantation, the samples were dipped in the protein solutions for 2 hours. Then, the protein adsorption ratio between implanted and unimplanted regions was evaluated by detecting amount of nitrogen atoms on the surface by X-ray photoelectron spectroscopy (XPS). As a result, the protein-precedently-absorbed sample implanted at dose more than 3×1015 ions/cm2 showed the large gelatin adsorption ratio of more than 2, where the much densely populated cell-attachment was observed more than that on the implanted region of polystyrene without precedent adsorption of protein after cell culture.

  13. Design of the new extraction grid for the NIO1 negative ion source

    NASA Astrophysics Data System (ADS)

    Veltri, P.; Cavenago, M.; Baltador, C.

    2015-04-01

    NIO1 is a compact source of negative ions jointly developed by RFX and INFN, to study the physics of production and acceleration of H- beams. Negative ions, up to 120 mA of current, are extracted from a radiofrequency driven plasma, by means of a gridded electrode (plasma grid, PG) featuring 9 apertures arranged in a 3x3 square lattice. The same aperture pattern is replicated in the following electrodes, allowing ion acceleration up to 60 keV. All electrodes are realized in copper, by electro-deposition technique, leaving empty slots in the metal to place magnets and to flow water for the grid cooling. The first set of electrodes was completed, installed in the source and tested. At the same time, an upgrade of the extraction system was carried out, in order to optimize the beam optics and to explore alternative electrostatic configurations. In particular, the accelerator will be modified by completely replacing the EG grid, exploiting the modularity of NIO1. The new electrode will feature other slots in between apertures, to place additional magnets. This allows testing different magnetic configurations, to optimize electron filtering and residual ion deflection. The present paper describes the theoretical activities driving the design of these new extractors, carried out with most updated numerical codes, and exploiting the synergy with the refined modeling of the 40 A ITER negative ion sources, under development at Consorzio RFX. Beam simulations are performed both with tracing codes (SLACCAD and OPERA) and with particle in cell codes (ACCPIC)

  14. Observation of electron spin resonance of negative ions in liquid helium

    NASA Technical Reports Server (NTRS)

    Reichert, J. F.; Dahm, A. J.

    1973-01-01

    Electron spin resonance signals of negative ions in liquid helium were observed. The line width and g-value were measured. Electrons injected into helium by field emission from ferromagnetic tips are shown to be polarized. A new technique for the measurement of electron spin polarization is presented.

  15. Negative Ion Drift Velocity and Longitudinal Diffusion in Mixtures of Carbon Disulfide and Methane

    NASA Technical Reports Server (NTRS)

    Dion, Michael P.; Son, S.; Hunter, S. D.; deNolfo, G. A.

    2011-01-01

    Negative ion drift velocity and longitudinal diffusion has been measured for gas mixtures of carbon disulfide (CS2) and methane (CH4)' Measurements were made as a function of total pressure, CS2 partial pressure and electric field. Constant mobility and thermal-limit longitudinal diffusion is observed for all gas mixtures tested. Gas gain for some of the mixtures is also included.

  16. ELECTRON AFFINITIES OF POLYNUCLEAR AROMATIC HYDROCARBONS AND NEGATIVE ION CHEMICAL IONIZATION SENSITIVITIES

    EPA Science Inventory

    Negative-ion chemical-ionization mass spectrometry (NICI MS) has the potential to be a very useful technique in identifying various polycyclic aromatic hydrocarbons (PAHs) in soil and sediment samples. Some PAHs give much stronger signals under NICI MS conditions than others. On ...

  17. Cross-sections for the formation of negative ions by electron impact on silane

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.; Krishnakumar, E.; De A. E Souza, A. C.

    1991-01-01

    Cross-sections and appearance potentials for the production of various negative ion species by electron impact on SiH4 have been measured. They are compared with two previous measurements which widely differ with each other. Hess' law has been applied to predict the various possible channels of dissociation.

  18. Herbert P. Broida Prize Lecture: Probing chemical dynamics with negative ion photodetachment

    NASA Astrophysics Data System (ADS)

    Neumark, Daniel

    2013-03-01

    Photoelectron spectroscopy and its variants have been used in our laboratory to study diverse phenomena in chemical dynamics, including transition state spectroscopy, the electronic and vibrational spectroscopy of clusters, the photodissociation of reactive free radicals, hydrated electron dynamics in clusters and liquid jets, and the ultrafast dynamics of helium nanodroplets. This talk will focus on two examples of this type of work: slow electron velocity map imaging (SEVI) of trapped and cooled negative ions, and time-resolved photoelectron spectroscopy (TRPES) of negative ions. SEVI of cold ions represents a powerful means of performing high resolution photoelectron spectroscopy on complex species. Time-resolved radiation chemistry in nucleobases will be carried out with TRPES. In this work, starting with iodide-nucleobase complexes, we inject electrons into low-lying unoccupied orbitals of the nucleobase and follow the ensuing dynamics.

  19. New source of MeV negative ion and neutral atom beams

    NASA Astrophysics Data System (ADS)

    Ter-Avetisyan, S.; Braenzel, J.; Schnürer, M.; Prasad, R.; Borghesi, M.; Jequier, S.; Tikhonchuk, V.

    2016-02-01

    The scenario of "electron-capture and -loss" was recently proposed for the formation of negative ion and neutral atom beams with MeV kinetic energies. However, it does not explain why the formation of negative ions in a liquid spray is much more efficient than with an isolated atom. The role of atomic excited states in the charge-exchange processes is considered, and it is shown that it cannot account for the observed phenomena. The processes are more complex than the single electron-capture and -loss approach. It is suggested that the shell effects in the electronic structure of the projectile ion and/or target atoms may influence the capture/loss probabilities.

  20. Summary of the status of negative-ion-based neutral beams

    SciTech Connect

    Cooper, W.S.

    1983-01-01

    Negative-ion-based neutral beam systems can perform multiple functions for fusion reactors, such as heating, current drive in tokamak reactors, and establishing and maintaining potential barriers in tandem mirror reactors. Practical systems operating continuously at the 200 keV, 1 MW level can be built using present-day technology. Ion sources have been demonstrated that produce D/sup -/ beams with <5% electron content, and that operate at linear current densities that are within a factor of 2 of what conservatively designed accelerator/transport structures can handle. Concepts are in hand for transporting the negative ion beam through a neutron maze before neutralization, thus permitting a radiation-hardened beamline. With an advanced laser photoneutralizer, overall system power efficiencies of 70% should be possible. A national program is being planned to achieve the goal of application of 475 keV systems on a mirror ETR in 1994.

  1. The photodetachment cross-section and threshold energy of negative ions in carbon dioxide

    NASA Technical Reports Server (NTRS)

    Helmy, E. M.; Woo, S. B.

    1974-01-01

    Threshold energy and sunlight photodetachment measurements on negative carbon dioxide ions, using a 2.5 kw light pressure xenon lamp, show that: (1) Electron affinity of CO3(+) is larger than 2.7 e.V. and that an isomeric form of CO3(+) is likely an error; (2) The photodetachment cross section of CO3(-) will roughly be like a step function across the range of 4250 to 2500A, having its threshold energy at 4250A; (3) Sunlight photodetachment rate for CO3(-) is probably much smaller than elsewhere reported; and (4) The probability of having photodetached electrons re-attach to form negative ions is less than 1%. Mass identifying drift tube tests confirm that the slower ion is CO3(-), formed through the O(-) + 2CO2 yields CO3(-) + CO2 reaction.

  2. [Negative air ions generated by plants upon pulsed electric field stimulation applied to soil].

    PubMed

    Wu, Ren-ye; Deng, Chuan-yuan; Yang, Zhi-jian; Weng, Hai-yong; Zhu, Tie-jun-rong; Zheng, Jin-gui

    2015-02-01

    This paper investigated the capacity of plants (Schlumbergera truncata, Aloe vera var. chinensis, Chlorophytum comosum, Schlumbergera bridgesii, Gymnocalycium mihanovichii var. friedrichii, Aspidistra elatior, Cymbidium kanran, Echinocactus grusonii, Agave americana var. marginata, Asparagus setaceus) to generate negative air ions (NAI) under pulsed electric field stimulation. The results showed that single plant generated low amounts of NAI in natural condition. The capacity of C. comosum and G. mihanovichii var. friedrichii generated most NAI among the above ten species, with a daily average of 43 ion · cm(-3). The least one was A. americana var. marginata with the value of 19 ion · cm(-3). When proper pulsed electric field stimulation was applied to soil, the NAI of ten plant species were greatly improved. The effect of pulsed electric field u3 (average voltage over the pulse period was 2.0 x 10(4) V, pulse frequency was 1 Hz, and pulse duration was 50 ms) was the greatest. The mean NAI concentration of C. kanran was the highest 1454967 ion · cm(-3), which was 48498.9 times as much as that in natural condition. The lowest one was S. truncata with the value of 34567 ion · cm(-3), which was 843.1 times as much as that in natural condition. The capacity of the same plants to generate negative air ion varied extremely under different intensity pulsed electric fields. PMID:26094455

  3. The emittances and brightnesses of high-intensity negative ion sources

    SciTech Connect

    Alton, G.D.; McConnell, J.W.

    1987-01-01

    The emittances of high-intensity ion beams extracted from cesium sputter negative ion sources equipped with cylindrical and ellipsoidal solid tungsten and spiral-wound tantalum (General Ionex Corporation, Model 860), and cesium surface ionizers have been measured for several ion species, including /sup 12/C/sup -/, /sup 28/Si/sup -/, /sup 58/Ni/sup -/, and /sup 197/Au/sup -/. While certain sets of data from the ellipsoidal and cylindrical geometry ionizer sources suggest a moderate growth in emittance with increasing negative ion beam intensity I over the range of intensities investigated (5 less than or equal to 1 less than or equal to 60 ..mu..A) of perhaps 20%, not all data exhibit this dependence, especially those from the Model 860 source. As well, no evidence of an emittance dependence on ion mass of a monotonic nature was found. The emittances of ion beams at the 80% intensity level from the Model 860 source are found to be higher on the average by factors of 1.8 and 1.7, respectively, than those from sources equipped with ellipsoidal and cylindrical geometry cesium surface ionizers.

  4. [Negative air ions generated by plants upon pulsed electric field stimulation applied to soil].

    PubMed

    Wu, Ren-ye; Deng, Chuan-yuan; Yang, Zhi-jian; Weng, Hai-yong; Zhu, Tie-jun-rong; Zheng, Jin-gui

    2015-02-01

    This paper investigated the capacity of plants (Schlumbergera truncata, Aloe vera var. chinensis, Chlorophytum comosum, Schlumbergera bridgesii, Gymnocalycium mihanovichii var. friedrichii, Aspidistra elatior, Cymbidium kanran, Echinocactus grusonii, Agave americana var. marginata, Asparagus setaceus) to generate negative air ions (NAI) under pulsed electric field stimulation. The results showed that single plant generated low amounts of NAI in natural condition. The capacity of C. comosum and G. mihanovichii var. friedrichii generated most NAI among the above ten species, with a daily average of 43 ion · cm(-3). The least one was A. americana var. marginata with the value of 19 ion · cm(-3). When proper pulsed electric field stimulation was applied to soil, the NAI of ten plant species were greatly improved. The effect of pulsed electric field u3 (average voltage over the pulse period was 2.0 x 10(4) V, pulse frequency was 1 Hz, and pulse duration was 50 ms) was the greatest. The mean NAI concentration of C. kanran was the highest 1454967 ion · cm(-3), which was 48498.9 times as much as that in natural condition. The lowest one was S. truncata with the value of 34567 ion · cm(-3), which was 843.1 times as much as that in natural condition. The capacity of the same plants to generate negative air ion varied extremely under different intensity pulsed electric fields.

  5. Generalization of the Child-Langmuir law to the alternate extraction of positive and negative ions

    SciTech Connect

    Lafleur, T.; Aanesland, A.

    2014-12-15

    Using a combined analytical and simulation approach, we investigate positive and negative ion extraction between two electrodes from an ion-ion plasma source. With a square voltage waveform applied to the electrodes, we obtain approximate analytical solutions for the time-averaged extracted current densities, which are given simply by: J{sub p}{sup ac}=[α−fL√((M{sub p})/(q{sub p}V{sub 0}) )]J{sub p}{sup dc}, and J{sub n}{sup ac}=[(1−α)−fL√((M{sub n})/(q{sub n}V{sub 0}) )]J{sub n}{sup dc}, where J{sup ac} is the time-averaged current density, α is the square waveform duty cycle, f is the frequency, L is the electrode gap length, M is the ion mass, q is the ion charge, V{sub 0} is the applied voltage amplitude, J{sup dc} is the dc extracted current density, and the subscripts p and n refer to positive and negative ions, respectively. In particular, if J{sup dc} is the dc space-charge limited current density, then these equations describe the square waveform generalization of the Child-Langmuir law.

  6. 30 years of high-intensity negative ion sources for accelerators

    SciTech Connect

    Vadim Dudnikov

    2001-07-25

    Thirty years ago, July 1, 1971, significant enhancement of negative ion emission from a gas discharge following an admixture of cesium was observed for the first time. This observation became the basis for the development of Surface Plasma Sources (SPS) for efficient production of negative ions from the interaction of plasma particles with electrodes on which adsorbed cesium reduced the surface work-function. The emission current density of negative ions increased rapidly from j {approximately} 10 mA/cm{sup 2} to 3.7 A/cm{sup 2} with a flat cathode and up to 8 A/cm{sup 2} with an optimized geometrical focusing in the long pulse SPS, and to 0.3 A/cm{sup 2} for DC SPS, recently increased up to 0.7 A/cm{sup 2}. Discovery of charge-exchange cooling helped decrease the negative ion temperature T below 1 eV, and increase brightness by many orders to a level compatible with the best proton sources, B = j/T> 1 A/cm{sup 2} eV. The combination of the SPS with charge-exchange injection improved large accelerators operation and has permitted beam accumulation up to space-charge limit and overcome this limit several times. The early SPS for accelerators have been in operation without modification for {approximately} 25 years. Advanced version of the SPS for accelerators is described. Features of negative ion beam formation, transportation, space-charge neutralization-overneutralization, and instability damping is considered. Practical aspects of SPS operation and high brightness beam production is discussed.

  7. Modulating memristive performance of hexagonal WO3 nanowire by water-oxidized hydrogen ion implantation.

    PubMed

    Zhou, Yong; Peng, Yuehua; Yin, Yanling; Zhou, Fang; Liu, Chang; Ling, Jing; Lei, Le; Zhou, Weichang; Tang, Dongsheng

    2016-01-01

    In a two-terminal Au/hexagonal WO3 nanowire/Au device, ions drifting or carriers self-trapping under external electrical field will modulate the Schottky barriers between the nanowire and electrodes, and then result in memristive effect. When there are water molecules adsorbed on the surface of WO3 nanowire, hydrogen ions will generate near the positively-charged electrode and transport in the condensed water film, which will enhance the memristive performance characterized by analogic resistive switching remarkably. When the bias voltage is swept repeatedly under high relative humidity level, hydrogen ions will accumulate on the surface and then implant into the lattice of the WO3 nanowire, which leads to a transition from semiconducting WO3 nanowire to metallic HxWO3 nanowire. This insulator-metal transition can be realized more easily after enough electron-hole pairs being excited by laser illumination. The concentration of hydrogen ions in HxWO3 nanowire will decrease when the device is exposed to oxygen atmosphere or the bias voltage is swept in atmosphere with low relative humidity. By modulating the concentration of hydrogen ions, conductive hydrogen tungsten bronze filament might form or rupture near electrodes when the polarity of applied voltage changes, which will endow the device with memristive performance characterized by digital resistive switching. PMID:27600368

  8. Near-surface hydrogen depletion of diamond-like carbon films produced by direct ion deposition

    NASA Astrophysics Data System (ADS)

    Markwitz, Andreas; Gupta, Prasanth; Mohr, Berit; Hübner, René; Leveneur, Jerome; Zondervan, Albert; Becker, Hans-Werner

    2016-03-01

    Amorphous atomically flat diamond-like carbon (DLC) coatings were produced by direct ion deposition using a system based on a Penning ion source, butane precursor gas and post acceleration. Hydrogen depth profiles of the DLC coatings were measured with the 15N R-NRA method using the resonant nuclear reaction 1H(15N, αγ)12C (Eres = 6.385 MeV). The films produced at 3.0-10.5 kV acceleration voltage show two main effects. First, compared to average elemental composition of the film, the near-surface region is hydrogen depleted. The increase of the hydrogen concentration by 3% from the near-surface region towards the bulk is attributed to a growth model which favours the formation of sp2 hybridised carbon rich films in the film formation zone. Secondly, the depth at which the maximum hydrogen concentration is measured increases with acceleration voltage and is proportional to the penetration depth of protons produced by the ion source from the precursor gas. The observed effects are explained by a deposition process that takes into account the contributions of ion species, hydrogen effusion and preferential displacement of atoms during direct ion deposition.

  9. Modulating memristive performance of hexagonal WO3 nanowire by water-oxidized hydrogen ion implantation

    PubMed Central

    Zhou, Yong; Peng, Yuehua; Yin, Yanling; Zhou, Fang; Liu, Chang; Ling, Jing; Lei, Le; Zhou, Weichang; Tang, Dongsheng

    2016-01-01

    In a two-terminal Au/hexagonal WO3 nanowire/Au device, ions drifting or carriers self-trapping under external electrical field will modulate the Schottky barriers between the nanowire and electrodes, and then result in memristive effect. When there are water molecules adsorbed on the surface of WO3 nanowire, hydrogen ions will generate near the positively-charged electrode and transport in the condensed water film, which will enhance the memristive performance characterized by analogic resistive switching remarkably. When the bias voltage is swept repeatedly under high relative humidity level, hydrogen ions will accumulate on the surface and then implant into the lattice of the WO3 nanowire, which leads to a transition from semiconducting WO3 nanowire to metallic HxWO3 nanowire. This insulator-metal transition can be realized more easily after enough electron-hole pairs being excited by laser illumination. The concentration of hydrogen ions in HxWO3 nanowire will decrease when the device is exposed to oxygen atmosphere or the bias voltage is swept in atmosphere with low relative humidity. By modulating the concentration of hydrogen ions, conductive hydrogen tungsten bronze filament might form or rupture near electrodes when the polarity of applied voltage changes, which will endow the device with memristive performance characterized by digital resistive switching. PMID:27600368

  10. Modulating memristive performance of hexagonal WO3 nanowire by water-oxidized hydrogen ion implantation.

    PubMed

    Zhou, Yong; Peng, Yuehua; Yin, Yanling; Zhou, Fang; Liu, Chang; Ling, Jing; Lei, Le; Zhou, Weichang; Tang, Dongsheng

    2016-01-01

    In a two-terminal Au/hexagonal WO3 nanowire/Au device, ions drifting or carriers self-trapping under external electrical field will modulate the Schottky barriers between the nanowire and electrodes, and then result in memristive effect. When there are water molecules adsorbed on the surface of WO3 nanowire, hydrogen ions will generate near the positively-charged electrode and transport in the condensed water film, which will enhance the memristive performance characterized by analogic resistive switching remarkably. When the bias voltage is swept repeatedly under high relative humidity level, hydrogen ions will accumulate on the surface and then implant into the lattice of the WO3 nanowire, which leads to a transition from semiconducting WO3 nanowire to metallic HxWO3 nanowire. This insulator-metal transition can be realized more easily after enough electron-hole pairs being excited by laser illumination. The concentration of hydrogen ions in HxWO3 nanowire will decrease when the device is exposed to oxygen atmosphere or the bias voltage is swept in atmosphere with low relative humidity. By modulating the concentration of hydrogen ions, conductive hydrogen tungsten bronze filament might form or rupture near electrodes when the polarity of applied voltage changes, which will endow the device with memristive performance characterized by digital resistive switching.

  11. Negative ions: The overlooked species in thin film growth by pulsed laser deposition

    SciTech Connect

    Esposito, M.; Bator, M.; Lippert, T.; Schneider, C. W.; Wokaun, A.; Doebeli, M.

    2011-11-07

    Plasma plume species from a ceramic La{sub 0.4}Ca{sub 0.6}MnO{sub 3} target were studied by plasma mass spectrometry as a function of laser fluence, background gas, and deposition pressure to understand the interplay between plasma composition and oxide thin film growth by pulsed laser deposition. The plume composition reveals a significant contribution of up to 24% of negative ions, most notably using a N{sub 2}O background. The significance of negative ions for thin film growth is shown for La{sub 0.4}Ca{sub 0.6}MnO{sub 3} films grown in different background conditions where the best structural properties coincide with the largest amount of negative plasma species.

  12. Experimental validation of the dual positive and negative ion beam acceleration in the plasma propulsion with electronegative gases thruster

    SciTech Connect

    Rafalskyi, Dmytro Popelier, Lara; Aanesland, Ane

    2014-02-07

    The PEGASES (Plasma Propulsion with Electronegative Gases) thruster is a gridded ion thruster, where both positive and negative ions are accelerated to generate thrust. In this way, additional downstream neutralization by electrons is redundant. To achieve this, the thruster accelerates alternately positive and negative ions from an ion-ion plasma where the electron density is three orders of magnitude lower than the ion densities. This paper presents a first experimental study of the alternate acceleration in PEGASES, where SF{sub 6} is used as the working gas. Various electrostatic probes are used to investigate the source plasma potential and the energy, composition, and current of the extracted beams. We show here that the plasma potential control in such system is key parameter defining success of ion extraction and is sensitive to both parasitic electron current paths in the source region and deposition of sulphur containing dielectric films on the grids. In addition, large oscillations in the ion-ion plasma potential are found in the negative ion extraction phase. The oscillation occurs when the primary plasma approaches the grounded parts of the main core via sub-millimetres technological inputs. By controlling and suppressing the various undesired effects, we achieve perfect ion-ion plasma potential control with stable oscillation-free operation in the range of the available acceleration voltages (±350 V). The measured positive and negative ion currents in the beam are about 10 mA for each component at RF power of 100 W and non-optimized extraction system. Two different energy analyzers with and without magnetic electron suppression system are used to measure and compare the negative and positive ion and electron fluxes formed by the thruster. It is found that at alternate ion-ion extraction the positive and negative ion energy peaks are similar in areas and symmetrical in position with +/− ion energy corresponding to the amplitude of the applied

  13. Counterstreaming hydrogen and oxygen ions observed in the magnetosphere on ISEE-1

    NASA Technical Reports Server (NTRS)

    Horita, R. E.; Ungstrup, E.; Sharp, R. D.; Anderson, R. R.; Fitzenreiter, R. J.

    1985-01-01

    Counterstreaming ions or ions travelling simultaneously both parallel and antiparallel to the magnetic field direction have been briefly noted in the literature but have not been studied previously in depth. Over 60 counterstreaming ion (CSI) events observed on the ISEE-1 satellite have been studied. They were found to occur at altitudes of about 2 to 8 earth radii on L shells of about 5 to 12 in the evening-to-morning sector from about 1700-0900 LT. Often both oxygen and hydrogen ions at a number of energy levels are counterstreaming but some events show only either oxygen or hydrogen ions involved. One particularly interesting event shows only counterstreaming oxygen ions with 417 eV energy; oxygen ions of lower energy (215 eV) and above (630-17,000 eV) and all the hydrogen ions between 215-17,000 eV energy have lower fluxes and/or nearly isotropic pitch angle distributions. This event correlates well with wave activity in the 17-100 Hz band and is also accompanied by 200 eV downgoing and 400 eV upgoing electrons. Details of this event and the other counterstreaming events are presented.

  14. Operating modes of a hydrogen ion source based on a hollow-cathode pulsed Penning discharge.

    PubMed

    Oks, E M; Shandrikov, M V; Vizir, A V

    2016-02-01

    An ion source based on a hollow-cathode Penning discharge was switched to a high-current pulsed mode (tens of amperes and tens of microseconds) to produce an intense hydrogen ion beam. With molecular hydrogen (H2), the ion beam contained three species: H(+), H2(+), and H3(+). For all experimental conditions, the fraction of H2 (+) ions in the beam was about 10 ÷ 15% of the total ion beam current and varied little with ion source parameters. At the same time, the ratio of H(+) and H3(+) depended strongly on the discharge current, particularly on its distribution in the gap between the hollow and planar cathodes. Increasing the discharge current increased the H(+) fraction in ion beam. The maximum fraction of H(+) reached 80% of the total ion beam current. Forced redistribution of the discharge current in the cathode gap for increasing the hollow cathode current could greatly increase the H3(+) fraction in the beam. At optimum parameters, the fraction of H3(+) ions reached 60% of the total ion beam current.

  15. Operating modes of a hydrogen ion source based on a hollow-cathode pulsed Penning discharge

    NASA Astrophysics Data System (ADS)

    Oks, E. M.; Shandrikov, M. V.; Vizir, A. V.

    2016-02-01

    An ion source based on a hollow-cathode Penning discharge was switched to a high-current pulsed mode (tens of amperes and tens of microseconds) to produce an intense hydrogen ion beam. With molecular hydrogen (H2), the ion beam contained three species: H+, H2+, and H3+. For all experimental conditions, the fraction of H2+ ions in the beam was about 10 ÷ 15% of the total ion beam current and varied little with ion source parameters. At the same time, the ratio of H+ and H3+ depended strongly on the discharge current, particularly on its distribution in the gap between the hollow and planar cathodes. Increasing the discharge current increased the H+ fraction in ion beam. The maximum fraction of H+ reached 80% of the total ion beam current. Forced redistribution of the discharge current in the cathode gap for increasing the hollow cathode current could greatly increase the H3+ fraction in the beam. At optimum parameters, the fraction of H3+ ions reached 60% of the total ion beam current.

  16. Thermodynamics of various F420 coenzyme models as sources of electrons, hydride ions, hydrogen atoms and protons in acetonitrile.

    PubMed

    Xia, Ke; Shen, Guang-Bin; Zhu, Xiao-Qing

    2015-06-14

    32 F420 coenzyme models with alkylation of the three different N atoms (N1, N3 and N10) in the core structure (XFH(-)) were designed and synthesized and the thermodynamic driving forces (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the 32 XFH(-) releasing hydride ions, hydrogen atoms and electrons, the thermodynamic driving forces of the 32 XFH˙ releasing protons and hydrogen atoms and the thermodynamic driving forces of XF(-)˙ releasing electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The effects of the methyl group at N1, N3 and N10 and a negative charge on N1 and N10 atoms on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were examined; the results show that seating arrangements of the methyl group and the negative charge have remarkably different effects on the thermodynamic properties of the F420 coenzyme models and their related reaction intermediates. The effects of the substituents at C7 and C8 on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were also examined; the results show that the substituents at C7 and C8 have good Hammett linear free energy relationships with the six thermodynamic parameters. Meanwhile, a reasonable determination of possible reactions between members of the F420 family and NADH family in vivo was given according to a thermodynamic analysis platform constructed using the elementary step thermodynamic parameter of F420 coenzyme model 2FH(-) and NADH model MNAH releasing hydride ions in acetonitrile. The information disclosed in this work can not only fill a gap in the chemical thermodynamics of F420 coenzyme models as a class of very important organic sources of electrons, hydride ions, hydrogen atoms and protons, but also strongly promote the fast development of the chemistry and applications of F420 coenzyme.

  17. Thermodynamics of various F420 coenzyme models as sources of electrons, hydride ions, hydrogen atoms and protons in acetonitrile.

    PubMed

    Xia, Ke; Shen, Guang-Bin; Zhu, Xiao-Qing

    2015-06-14

    32 F420 coenzyme models with alkylation of the three different N atoms (N1, N3 and N10) in the core structure (XFH(-)) were designed and synthesized and the thermodynamic driving forces (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the 32 XFH(-) releasing hydride ions, hydrogen atoms and electrons, the thermodynamic driving forces of the 32 XFH˙ releasing protons and hydrogen atoms and the thermodynamic driving forces of XF(-)˙ releasing electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The effects of the methyl group at N1, N3 and N10 and a negative charge on N1 and N10 atoms on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were examined; the results show that seating arrangements of the methyl group and the negative charge have remarkably different effects on the thermodynamic properties of the F420 coenzyme models and their related reaction intermediates. The effects of the substituents at C7 and C8 on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were also examined; the results show that the substituents at C7 and C8 have good Hammett linear free energy relationships with the six thermodynamic parameters. Meanwhile, a reasonable determination of possible reactions between members of the F420 family and NADH family in vivo was given according to a thermodynamic analysis platform constructed using the elementary step thermodynamic parameter of F420 coenzyme model 2FH(-) and NADH model MNAH releasing hydride ions in acetonitrile. The information disclosed in this work can not only fill a gap in the chemical thermodynamics of F420 coenzyme models as a class of very important organic sources of electrons, hydride ions, hydrogen atoms and protons, but also strongly promote the fast development of the chemistry and applications of F420 coenzyme

  18. Fluid Model Analysis of the Distribution of the Negative Ion Density before the Extraction from a Tandem Type of a Plasma Source

    SciTech Connect

    St Lishev, Stiliyan; Shivarova, Antonia P.; Tarnev, Khristo Ts.

    2011-09-26

    Unified description of the expansion (through a magnetic filter) and extraction regions, including also the driver, of volume-production based sources of negative hydrogen ions is presented in the study. The model is one-dimensional, developed within the fluid plasma theory. It covers description of both the second chamber of the tandem sources and a single inductively-driven (with a planar coil) discharge of a matrix source. Four parameters have been varied in the analysis of the results: type, position and magnitude of the filter field and rf power applied for the discharge maintenance. The obtained results for the spatial distribution of the plasma parameters as well as for the electronegativity, for the negative ion beam current and its ratio to the electron current at the position of the extraction are discussed regarding optimum conditions for the source operation. The conclusion is that a magnetic field extended over a large region till the extraction favors locality in the discharge behavior and, respectively, the local production of the negative ions. This leads to high density of the extracted negative ion beam current at reasonable values of its ratio to the electron current density.

  19. Dopant-assisted negative photoionization ion mobility spectrometry for sensitive detection of explosives.

    PubMed

    Cheng, Shasha; Dou, Jian; Wang, Weiguo; Chen, Chuang; Hua, Lei; Zhou, Qinghua; Hou, Keyong; Li, Jinghua; Li, Haiyang

    2013-01-01

    Ion mobility spectrometry (IMS) is a key trace detection technique for explosives and the development of a simple, stable, and efficient nonradioactive ionization source is highly demanded. A dopant-assisted negative photoionization (DANP) source has been developed for IMS, which uses a commercial VUV krypton lamp to ionize acetone as the source of electrons to produce negative reactant ions in air. With 20 ppm of acetone as the dopant, a stable current of reactant ions of 1.35 nA was achieved. The reactant ions were identified to be CO(3)(-)(H(2)O)(n) (K(0) = 2.44 cm(2) V(-1) s(-1)) by atmospheric pressure time-of-flight mass spectrometry, while the reactant ions in (63)Ni source were O(2)(-)(H(2)O)(n) (K(0) = 2.30 cm(2) V(-1) s(-1)). Finally, its capabilities for detection of common explosives including ammonium nitrate fuel oil (ANFO), 2,4,6-trinitrotoluene (TNT), N-nitrobis(2-hydroxyethyl)amine dinitrate (DINA), and pentaerythritol tetranitrate (PETN) were evaluated, and the limits of detection of 10 pg (ANFO), 80 pg (TNT), and 100 pg (DINA) with a linear range of 2 orders of magnitude were achieved. The time-of-flight mass spectra obtained with use of DANP source clearly indicated that PETN and DINA can be directly ionized by the ion-association reaction of CO(3)(-) to form PETN·CO(3)(-) and DINA·CO(3)(-) adduct ions, which result in good sensitivity for the DANP source. The excellent stability, good sensitivity, and especially the better separation between the reactant and product ion peaks make the DANP a potential nonradioactive ionization source for IMS.

  20. Gadolinium-hydrogen ion exchange of zirconium phosphate

    NASA Technical Reports Server (NTRS)

    Liu, D. C.; Power, J. L.

    1972-01-01

    The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.

  1. Negative Linear Compressibility in Organic Mineral Ammonium Oxalate Monohydrate with Hydrogen Bonding Wine-Rack Motifs.

    PubMed

    Qiao, Yuancun; Wang, Kai; Yuan, Hongsheng; Yang, Ke; Zou, Bo

    2015-07-16

    Negative linear compressibility (NLC) is a relatively uncommon phenomenon and rarely studied in organic systems. Here we provide the direct evidence of the persistent NLC in organic mineral ammonium oxalate monohydrate under high pressure using synchrotron X-ray powder diffraction, Raman spectroscopy and density functional theory (DFT) calculation. Synchrotron X-ray powder diffraction measurement reveals that ammonium oxalate monohydrate shows both positive and negative linear compressibility along b-axis before 11.5 GPa. The red shift of the external Raman modes and abnormal changes of several selected internal modes in high-pressure Raman spectra further confirmed the NLC. DFT calculations demonstrate that the N-H···O hydrogen bonding "wine-rack" motifs result in the NLC along b-axis in ammonium oxalate monohydrate. We anticipate the high-pressure study of ammonium oxalate monohydrate may represent a promising strategy for accelerating the pace of exploitation and improvement of NLC materials especially in organic systems. PMID:26266859

  2. Method and source for producing a high concentration of positively charged molecular hydrogen or deuterium ions

    DOEpatents

    Ehlers, Kenneth W.; Leung, Ka-Ngo

    1988-01-01

    A high concentration of positive molecular ions of hydrogen or deuterium gas is extracted from a positive ion source having a short path length of extracted ions, relative to the mean free path of the gas molecules, to minimize the production of other ion species by collision between the positive ions and gas molecules. The ion source has arrays of permanent magnets to produce a multi-cusp magnetic field in regions remote from the plasma grid and the electron emitters, for largely confining the plasma to the space therebetween. The ion source has a chamber which is short in length, relative to its transverse dimensions, and the electron emitters are at an even shorter distance from the plasma grid, which contains one or more extraction apertures.

  3. Origin of extracted negative ions by 3D PIC-MCC modeling. Surface vs Volume comparison

    NASA Astrophysics Data System (ADS)

    Mochalskyy, S.; Lifschitz, A. F.; Minea, T.

    2011-09-01

    The development of a high performance negative ion (NI) source constitutes a crucial step in the construction of Neutral Beam Injector (NBI) of the future fusion reactor ITER. NI source should deliver 40 A of H- (or D-), which is a technical and scientific challenge, and requires a deeper understanding of the underlying physics of the source and its magnetic filter. The present knowledge of the ion extraction mechanism from the negative ion source is limited and concerns magnetized plasma sheaths used to avoid electrons being co-extracted from the plasma together with the NI. Moreover, due to the asymmetry induced by the ITER crossed magnetic configuration used to filter the electrons, any realistic study of this problem must consider the three spatial dimensions. To address this problem, a 3D Particles-in-Cell electrostatic collisional code was developed, specifically designed for this system. Binary collisions between the particles are introduced using Monte Carlo Collision scheme. The complex orthogonal magnetic field that is applied to deflect electrons is also taken into account. This code, called ONIX (Orsay Negative Ion eXtraction), was used to investigate the plasma properties and the transport of the charged particles close to a typical extraction aperture [1]. This contribution focuses on the limits for the extracted NI current from both, plasma volume and aperture wall. Results of production, destruction, and transport of H- in the extraction region are presented. The extraction efficiency of H- from the volume is compared to the one of H- coming from the wall.

  4. Improvements of the magnetic field design for SPIDER and MITICA negative ion beam sources

    SciTech Connect

    Chitarin, G.; Agostinetti, P.; Aprile, D.; Marconato, N.; Veltri, P.

    2015-04-08

    The design of the magnetic field configuration in the SPIDER and MITICA negative ion beam sources has evolved considerably during the past four years. This evolution was driven by three factors: 1) the experimental results of the large RF-driven ion sources at IPP, which have provided valuable indications on the optimal magnetic configurations for reliable RF plasma source operation and for large negative ion current extraction, 2) the comprehensive beam optics and heat load simulations, which showed that the magnetic field configuration in the accelerator is crucial for keeping the heat load due to electrons on the accelerator grids within tolerable limits, without compromising the optics of the negative ion beam in the foreseen operating scenarios, 3) the progress of the detailed mechanical design of the accelerator, which stimulated the evaluation of different solutions for the correction of beamlet deflections of various origin and for beamlet aiming. On this basis, new requirements and solution concepts for the magnetic field configuration in the SPIDER and MITICA beam sources have been progressively introduced and updated until the design converged. The paper presents how these concepts have been integrated into a final design solution based on a horizontal “long-range” field (few mT) in combination with a “local” vertical field of some tens of mT on the acceleration grids.

  5. Multiplex Mass Spectrometric Imaging with Polarity Switching for Concurrent Acquisition of Positive and Negative Ion Images

    NASA Astrophysics Data System (ADS)

    Korte, Andrew R.; Lee, Young Jin

    2013-06-01

    We have recently developed a multiplex mass spectrometry imaging (MSI) method which incorporates high mass resolution imaging and MS/MS and MS3 imaging of several compounds in a single data acquisition utilizing a hybrid linear ion trap-Orbitrap mass spectrometer (Perdian and Lee, Anal. Chem. 82, 9393-9400, 2010). Here we extend this capability to obtain positive and negative ion MS and MS/MS spectra in a single MS imaging experiment through polarity switching within spiral steps of each raster step. This methodology was demonstrated for the analysis of various lipid class compounds in a section of mouse brain. This allows for simultaneous imaging of compounds that are readily ionized in positive mode (e.g., phosphatidylcholines and sphingomyelins) and those that are readily ionized in negative mode (e.g., sulfatides, phosphatidylinositols and phosphatidylserines). MS/MS imaging was also performed for a few compounds in both positive and negative ion mode within the same experimental set-up. Insufficient stabilization time for the Orbitrap high voltage leads to slight deviations in observed masses, but these deviations are systematic and were easily corrected with a two-point calibration to background ions.

  6. An experimental study of waveguide coupled microwave heating with conventional multicusp negative ion sources

    SciTech Connect

    Komppula, J.; Kalvas, T.; Koivisto, H.; Laulainen, J.; Tarvainen, O.

    2015-04-08

    Negative ion production with conventional multicusp plasma chambers utilizing 2.45 GHz microwave heating is demonstrated. The experimental results were obtained with the multicusp plasma chambers and extraction systems of the RF-driven RADIS ion source and the filament driven arc discharge ion source LIISA. A waveguide microwave coupling system, which is almost similar to the one used with the SILHI ion source, was used. The results demonstrate that at least one third of negative ion beam obtained with inductive RF-coupling (RADIS) or arc discharge (LIISA) can be achieved with 1 kW of 2.45 GHz microwave power in CW mode without any modification of the plasma chamber. The co-extracted electron to H{sup −} ratio and the optimum pressure range were observed to be similar for both heating methods. The behaviour of the plasma implies that the energy transfer from the microwaves to the plasma electrons is mainly an off-resonance process.

  7. Probing Dynamics from Within in Negative Ions, Neutral Molecules and van der Waals Clusters

    NASA Astrophysics Data System (ADS)

    Berrah, Nora

    2006-05-01

    We have investigated with unprecedented levels of detail, processes and phenomena involving photodetachment of negative ions and photoionization of molecules and van der Waals clusters using the brightness, spectral resolution, tunability and polarization of the Advanced Light Source at Lawrence Berkeley National Laboratory. Photodetachment of negative ions exhibit structure and processes differing substantially from corresponding processes in neutral and positive ions, owing to the dominance of correlation in both the initial and final states. We will report on investigations carried out in inner-valence CN^- molecules giving rise to absolute double photodetachment cross sections as well as on fragmentation of negative ions clusters. We will also present absolute inner-shell photodetachment of atoms leading to multi-Auger decay [1] and discuss threshold laws [2] and PCI effects [3]. The measurements were conducted using collinear photon-ion spectroscopy. The evolution of inner-shell photoionization of clusters, as a function of photon energy, will be presented and compared to analogous measurements in atoms. The measurements were conducted using angle resolved two-dimensional photoelectron spectroscopy. Molecular fragmentation results using an ion imaging detector will briefly be presented. [1] R. C. Bilodeau, J. D. Bozek, G. D. Ackerman, N. D. Gibson, C. W.Walter, A. Aguilar, G. Turri, I. Dumitriu and N. Berrah, PRA 72, 050701(R), 2005. [2] R. C. Bilodeau, J. D. Bozek, N. D. Gibson, C. W. Walter, G. D. Ackerman, I. Dumitriu, and N. Berrah, Phys. Rev. Lett. 95, 083001 (2005). [3] R. C. Bilodeau, J. D. Bozek, A. Agular, G. D. Ackerman, and N. Berrah, (in press PRA brief report).

  8. Using Hydrogen Balloons to Display Metal Ion Spectra

    ERIC Educational Resources Information Center

    Maynard, James H.

    2008-01-01

    We have optimized a procedure for igniting hydrogen-filled balloons containing metal salts to obtain the brightest possible flash while minimizing the quantity of airborne combustion products. We report air quality measurements in a lecture hall immediately after the demonstration. While we recommend that this demonstration be done outdoors or in…

  9. Mixed Pierce-two-stream instability development in an extraction system of a negative ion source.

    PubMed

    Barminova, H Y; Chikhachev, A S

    2016-02-01

    Mixed Pierce-two-stream instability may occur in an extraction system of a negative ion source based on a volume-produced plasma. The reasons for instability development are discussed. Analytically the conditions of unstable beam propagation are determined. The instability threshold is shown to be increased compared with the pure Pierce instability. The influence of inclined perturbations on the instability behavior is investigated. The numerical calculations are performed in COMSOL Multiphysics. The simulation results confirm the existence of such a mixed instability appearance that develops due to both the electrons of the external circuit and the background positive ions. PMID:26931917

  10. The roles of electronic and nuclear stopping in the desorption valine negative molecular ions

    SciTech Connect

    Hunt, J.E.; Salehpour, M.; Fishel, D.L.; Tou, J.C.

    1988-01-01

    The yield of valine negative molecular ions has been measured as a function of Xe/sup +/, Kr/sup +/, and Ar/sup +/ primary ion velocity. The electronic and nuclear stopping powers are comparable in magnitude and opposite in slope in the experimental velocity region. The yield data are explained in terms of electronic stopping power alone, with no contribution from nuclear stopping power within the experimental error. Low molecular weight atomic species are found to be best described by a nuclear stopping power related process. 18 refs., 3 figs.

  11. Trapping of hydrogen atoms inside small beryllium clusters and their ions

    NASA Astrophysics Data System (ADS)

    Naumkin, F. Y.; Wales, D. J.

    2016-08-01

    Structure, stability and electronic properties are evaluated computationally for small Ben (n = 5-9) cluster cages accommodating atomic H inside and forming core-shell species. These parameters are predicted to vary significantly upon insertion of H, for ionic derivatives, and with the system size. In particular, the energy barrier for H-atom exit from the cage changes significantly for ions compared to the neutral counterparts. The corresponding effects predicted for cage assemblies suggest the possibility of efficient charge-control of hydrogen release. This, together with a high capacity for storing hydrogen in extended such assemblies might indicate a possible way towards feasible hydrogen-storage solutions.

  12. Combining Ion Mobility Spectrometry with Hydrogen-Deuterium Exchange and Top-Down MS for Peptide Ion Structure Analysis

    NASA Astrophysics Data System (ADS)

    Khakinejad, Mahdiar; Kondalaji, Samaneh Ghassabi; Maleki, Hossein; Arndt, James R.; Donohoe, Gregory C.; Valentine, Stephen J.

    2014-12-01

    The gas-phase conformations of electrosprayed ions of the model peptide KKDDDDIIKIIK have been examined by ion mobility spectrometry (IMS) and hydrogen deuterium exchange (HDX)-tandem mass spectrometry (MS/MS) techniques. [M+4H]4+ ions exhibit two conformers with collision cross sections of 418 Å2 and 471 Å2. [M+3H]3+ ions exhibit a predominant conformer with a collision cross section of 340 Å2 as well as an unresolved conformer (shoulder) with a collision cross section of ~367 Å2. Maximum HDX levels for the more compact [M+4H]4+ ions and the compact and partially-folded [M+3H]3+ ions are ~12.9, ~15.5, and ~14.9, respectively. Ion structures obtained from molecular dynamics simulations (MDS) suggest that this ordering of HDX level results from increased charge-site/exchange-site density for the more compact ions of lower charge. Additionally, a new model that includes two distance calculations (charge site to carbonyl group and carbonyl group to exchange site) for the computer-generated structures is shown to better correlate to the experimentally determined per-residue deuterium uptake. Future comparisons of IMS-HDX-MS data with structures obtained from MDS are discussed with respect to novel experiments that will reveal the HDX rates of individual residues.

  13. Numerical Analysis of Electronegative Plasma near the Extraction Grid in Negative Ion Sources

    SciTech Connect

    Kuppel, S.; Matsushita, D.; Hatayama, A.; Bacal, M.

    2009-03-12

    The effects of plasma electrode (PE) bias on the extraction process in a negative ion source are studied with a series of two-dimensional (2D) electrostatic particle simulations. Motion of charged particles in their self-consistent electric field is modeled by the Particle-In-Cell (PIC) method. The effect of a weak transverse magnetic field is also taken into account. Extracted electron current density gradually decreases as the PE bias increases, while the absolute value of PE net current density initially increases and is saturated for higher values of PE bias. The extracted negative ion current density reaches a weak peak when the PE bias approaches the bulk plasma potential (Vpf) in the case without the PE bias, but the decrease afterwards is mild. Physical mechanisms leading to these results are discussed.

  14. Negative ion formation by Rydberg electron transfer: Isotope-dependent rate constants

    SciTech Connect

    Carman, H.S. Jr.; Klots, C.E.; Compton, R.N.

    1991-01-01

    The formation of negative ions during collisions of rubidium atoms in selected ns and nd Rydberg states with carbon disulfide molecules has been studied for a range of effective principal quantum numbers (10 {le} n* {le} 25). For a narrow range of n* near n* = 17, rate constants for CS{sub 2}{sup {minus}} formation are found to depend upon the isotopic composition of the molecule, producing a negative ion isotope ratio (mass 78 to mass 76, amu) up to 10.5 times larger than the natural abundance ratio of CS{sub 2} isotopes in the reagent. The isotope ratio is found to depend strongly upon the initial quantum state of the Rydberg atom and perhaps upon the collision energy and CS{sub 2} temperature. 32 refs., 5 figs., 1 tab.

  15. Solitons at the critical density of negative ions in multicomponent plasmas

    SciTech Connect

    Ibohanbi Singh, K.H.; Das, G.C. )

    1989-12-01

    The derivation of solitary waves in generalized multicomponent plasmas shows that the negative ion introduces a critical density at which the characteristics of the solitons are studied. The soliton's behavior deriving through the Korteweg-deVries (K-dV) equation at the critical density shows that the nonlinearity of the wave vanishes, due to which the mode of study is augmented through a modified K-dV equation. Employing a higher order equation involving quadratic and cubic nonlinearities, the transition of the K-dV equation to a modified K-dV equation along with the conservation of the Sagdeev potential, which is not affected by the negative ions, is studied in detail. The results are compared with experimental observations.

  16. Distonic biradical anions. Synthesis and characterization of the 3,5-dehydrophenyl and 1,3,5-trimethylenebenzene negative ions

    SciTech Connect

    Hu, J.; Squires, R.R.

    1996-06-19

    We recently described a new method for producing intense beams of structurally-defined biradical negative ions (`distonic radical anions`) in the gas phase based on reactions between trimethylsilyl-substituted carbanions and molecular fluorine. We now wish to report the extension of this procedure to the rational synthesis of negative ions of triradicals, i.e., `distonic biradical anions.` The significance of these species is manifold. Polyradicals and their associated ions are the central focus of current efforts to produce synthetic organic ferromagnets. In this report, we describe the gas-phase synthesis and characterization of 3,5-dehydrophenyl anion, 1, and 1,3,5-trimethylenebenzene negative ion, 2. Ion 1 corresponds to the negative ion of the ({sigma},{sigma},{sigma}) triradical 1,3,5-benzenetriyl, and it can also be viewed as a deprotonated m-benzyne. 29 refs.

  17. Distortion effects in electron excitation of hydrogen atoms by impact of heavy ions

    SciTech Connect

    Ramirez, C.A.; Rivarola, R.D.

    1995-12-01

    Electron excitation from the fundamental state of hydrogen atoms by impact of bare ions is studied at intermediate and high collision velocities. Total cross sections for final {ital np} states by impact of protons, alpha particles, and He{sup +} ions are calculated using the symmetric eikonal approximation and compared with experimental data. This comparison supports the existence of distortion effects recently predicted by Bugacov and co-workers [Phys. Rev. A {bold 47}, 1052 (1993)]. The validity of scaling laws is analyzed.

  18. In-tank hydrogen-ferric ion recombination

    NASA Astrophysics Data System (ADS)

    Selverston, S.; Savinell, R. F.; Wainright, J. S.

    2016-08-01

    An H2sbnd Fe3+ recombination method is being developed for all-iron flow batteries. Working principles are described and a proof-of-concept in-tank reactor is demonstrated. A membrane-less galvanic reactor is characterized using potential, polarization and impedance measurements at hydrogen partial pressures ranging from 0.3 to 11.3 psig. Through a vertical reactor geometry, hydrogen recombination rates of up to 60 mA cm-2 were measured at PH2 = 4.5 psig for a reactor with a platinum loading of 3.2 mg cm-2, based on the geometric catalyzed area. This is equivalent to over 375 mA cm-2 with respect to the cross sectional area of the reactor at the waterline. This rate is sufficient that the reactor will readily fit inside the positive reservoir of a flow battery. The reactor was found to be resistant to degradation by flooding or catalyst loss.

  19. Design of the new extraction grid for the NIO1 negative ion source

    SciTech Connect

    Veltri, P. Baltador, C.; Cavenago, M.

    2015-04-08

    NIO1 is a compact source of negative ions jointly developed by RFX and INFN, to study the physics of production and acceleration of H{sup −} beams. Negative ions, up to 120 mA of current, are extracted from a radiofrequency driven plasma, by means of a gridded electrode (plasma grid, PG) featuring 9 apertures arranged in a 3x3 square lattice. The same aperture pattern is replicated in the following electrodes, allowing ion acceleration up to 60 keV. All electrodes are realized in copper, by electro-deposition technique, leaving empty slots in the metal to place magnets and to flow water for the grid cooling. The first set of electrodes was completed, installed in the source and tested. At the same time, an upgrade of the extraction system was carried out, in order to optimize the beam optics and to explore alternative electrostatic configurations. In particular, the accelerator will be modified by completely replacing the EG grid, exploiting the modularity of NIO1. The new electrode will feature other slots in between apertures, to place additional magnets. This allows testing different magnetic configurations, to optimize electron filtering and residual ion deflection. The present paper describes the theoretical activities driving the design of these new extractors, carried out with most updated numerical codes, and exploiting the synergy with the refined modeling of the 40 A ITER negative ion sources, under development at Consorzio RFX. Beam simulations are performed both with tracing codes (SLACCAD and OPERA) and with particle in cell codes (ACCPIC)

  20. Electron Energy Distribution Function Measurements by Langmuir Probe in ITER like Negative Ion Sources

    SciTech Connect

    Crowley, B.; Homfray, D.; Boilson, D.

    2007-08-10

    Determining d2I/dV2 from a traditional Langmuir probe trace using numerical techniques is inherently noisy and generally yields poor results. We have developed a Langmuir probe system based on a method first used in the 1950's by Boyd and Twiddy. The system measures the 2nd derivative directly. This paper presents results from the driver and extraction regions of the KAMABOKO III ITER like negative ion source.