Approximation of super-ions for single-file diffusion of multiple ions through narrow pores.
Kharkyanen, Valery N; Yesylevskyy, Semen O; Berezetskaya, Natalia M
2010-11-01
The general theory of the single-file multiparticle diffusion in the narrow pores could be greatly simplified in the case of inverted bell-like shape of the single-particle energy profile, which is often observed in biological ion channels. There is a narrow and deep groove in the energy landscape of multiple interacting ions in such profiles, which corresponds to the pre-defined optimal conduction pathway in the configurational space. If such groove exists, the motion of multiple ions can be reduced to the motion of single quasiparticle, called the superion, which moves in one-dimensional effective potential. The concept of the superions dramatically reduces the computational complexity of the problem and provides very clear physical interpretation of conduction phenomena in the narrow pores.
NASA Astrophysics Data System (ADS)
Albert, Felicie; Pak, A.; Kerr, S.; Lemos, N.; Link, A.; Patel, P.; Pollock, B. B.; Haberberger, D.; Froula, D.; Gauthier, M.; Glenzer, S. H.; Longman, A.; Manzoor, L.; Fedosejevs, R.; Tochitsky, S.; Joshi, C.; Fiuza, F.
2017-10-01
In this work, we report on electrostatic collisionless shock wave acceleration experiments that produced proton beams with peak energies between 10-17.5 MeV, with narrow energy spreads between Δ E / E of 10-20%, and with a total number of protons in these peaks of 1e7-1e8. These beams of ions were created by driving an electrostatic collisionless shock wave in a tailored near critical density plasma target using the ultra-intense ps duration Titan laser that operates at a wavelength of 1 um. The near critical density target was produced through the ablation of an initially 0.5 um thick Mylar foil with a separate low intensity laser. A narrow energy spread distribution of carbon / oxygen ions with a similar velocity to the accelerated proton distribution, consistent with the reflection and acceleration of ions from an electrostatic field, was also observed. This work was supported by Lawrence Livermore National Laboratory's Laboratory Directed Research and Development program under project 15-LW-095, and the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA2734.
The importance of dehydration in determining ion transport in narrow pores.
Richards, Laura A; Schäfer, Andrea I; Richards, Bryce S; Corry, Ben
2012-06-11
The transport of hydrated ions through narrow pores is important for a number of processes such as the desalination and filtration of water and the conductance of ions through biological channels. Here, molecular dynamics simulations are used to systematically examine the transport of anionic drinking water contaminants (fluoride, chloride, nitrate, and nitrite) through pores ranging in effective radius from 2.8 to 6.5 Å to elucidate the role of hydration in excluding these species during nanofiltration. Bulk hydration properties (hydrated size and coordination number) are determined for comparison with the situations inside the pores. Free energy profiles for ion transport through the pores show energy barriers depend on pore size, ion type, and membrane surface charge and that the selectivity sequence can change depending on the pore size. Ion coordination numbers along the trajectory showed that partial dehydration of the transported ion is the main contribution to the energy barriers. Ion transport is greatly hindered when the effective pore radius is smaller than the hydrated radius, as the ion has to lose some associated water molecules to enter the pore. Small energy barriers are still observed when pore sizes are larger than the hydrated radius due to re-orientation of the hydration shell or the loss of more distant water. These results demonstrate the importance of ion dehydration in transport through narrow pores, which increases the current level of mechanistic understanding of membrane-based desalination and transport in biological channels. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dollar, Franklin; Matsuoka, Takeshi; McGuffey, Christopher
2010-11-04
Recent simulations show that an idealized, high intensity, short pulse laser can generate quasi-monoenergetic proton beams with energies over 100 MeV in an interaction with a thin film. However, most short pulse laser facilities with sufficient intensity have difficulty controlling the nanosecond and picosecond contrast necessary to realize such a regime. Experiments were performed to investigate proton and ion acceleration from a high contrast, short pulse laser by employing dual plasma mirrors along with a deformable mirror at the HERCULES laser facility at the Center for Ultrafast Optical Sciences, University of Michigan. Plasma mirrors were characterized, allowing a 50% throughputmore » with an intensity contrast increase of 105. The focal spot quality was also exceptional, showing a 1.1 micron full width at half maximum (FWHM) focal diameter. Experiments were done using temporally cleaned 30 TW, 32 fs pulses to achieve an intensity of up to 10{sup 21} Wcm{sup -2} on Si{sub 3}N{sub 4} and Mylar targets with thicknesses ranging 50 nm to 13 microns. Proton beams with energy spreads below 2 MeV were observed from all thicknesses, peaking with energies up to 10.3 MeV and an energy spread of 0.8 MeV. Similar narrow energy spreads were observed for oxygen, nitrogen, and carbon at the silicon nitride thickness of 50 nm with energies up to 24 MeV with an energy spread of 3 MeV, whereas the energy spread is greatly increased at a larger thickness. Maximum energies were confirmed with CR39 track detectors, while a Thomson ion spectrometer was used to gauge the monoenergetic nature of the beam.« less
Ion acceleration with a narrow energy spectrum by nanosecond laser-irradiation of solid target
NASA Astrophysics Data System (ADS)
Altana, C.; Lanzalone, G.; Mascali, D.; Muoio, A.; Cirrone, G. A. P.; Schillaci, F.; Tudisco, S.
2016-02-01
In laser-driven plasma, ion acceleration of aluminum with the production of a quasi-monoenergetic beam has occurred. A useful device to analyze the ions is the Thomson parabolas spectrometer, a well-known diagnostic that is able to obtain information on charge-to-mass ratio and energy distribution of the charged particles. At the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS in Catania, experimental measures were carried out; the features of LENS are: Q-switched Nd:YAG laser with 2 J laser energy, 1064 nm fundamental wavelengths, and 6 ns pulse duration.
Ion acceleration with a narrow energy spectrum by nanosecond laser-irradiation of solid target
DOE Office of Scientific and Technical Information (OSTI.GOV)
Altana, C., E-mail: altana@lns.infn.it; Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania; Lanzalone, G.
2016-02-15
In laser-driven plasma, ion acceleration of aluminum with the production of a quasi-monoenergetic beam has occurred. A useful device to analyze the ions is the Thomson parabolas spectrometer, a well-known diagnostic that is able to obtain information on charge-to-mass ratio and energy distribution of the charged particles. At the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS in Catania, experimental measures were carried out; the features of LENS are: Q-switched Nd:YAG laser with 2 J laser energy, 1064 nm fundamental wavelengths, and 6 ns pulse duration.
NASA Technical Reports Server (NTRS)
Ungstrup, E.; Klumpar, D. M.; Heikkila, W. J.
1979-01-01
The soft particle spectrometer on the Isis 2 spacecraft occasionally observes fluxes of ions moving upward out of the ionosphere in the vicinity of the auroral oval. These ion fluxes are characterized by a sharp pitch angle distribution usually peaked at an angle somewhat greater than 90 deg, indicative of particles heated to a large transverse temperature in a narrow range below the spacecraft. The observations are interpreted in terms of electrostatic ion cyclotron waves, which heat the ions to superthermal energies transverse to the earth's magnetic field. When the transverse energy increases, the repulsive force of the earth's magnetic field, proportional to the particle magnetic moment, repels the particles away from the earth.
NASA Astrophysics Data System (ADS)
Rosén, Johanna; Anders, André; Mráz, Stanislav; Atiser, Adil; Schneider, Jochen M.
2006-06-01
The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range of 0.5-8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as well as a narrow IED. These data may enable tailoring thin film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Agarwal, Ankur; Kushner, Mark J.; Iowa State University, Department of Electrical and Computer Engineering, 104 Marston Hall, Ames, Iowa 50011-2151
2005-09-15
The distributions of ion energies incident on the wafer significantly influence feature profiles and selectivity during plasma etching. Control of ion energies is typically obtained by varying the amplitude or frequency of a radio frequency sinusoidal bias voltage applied to the substrate. The resulting ion energy distribution (IED), though, is generally broad. Controlling the width and shape of the IED can potentially improve etch selectivity by distinguishing between threshold energies of surface processes. In this article, control of the IED was computationally investigated by applying a tailored, nonsinusoidal bias waveform to the substrate of an inductively coupled plasma. The waveformmore » we investigated, a quasi-dc negative bias having a short positive pulse each cycle, produced a narrow IED whose width was controllable based on the length of the positive spike and frequency. We found that the selectivity between etching Si and SiO{sub 2} in fluorocarbon plasmas could be controlled by adjusting the width and energy of the IED. Control of the energy of a narrow IED enables etching recipes that transition between speed and selectivity without change of gas mixture.« less
NASA Astrophysics Data System (ADS)
Gandhi, Y.; Rajanikanth, P.; Sundara Rao, M.; Ravi Kumar, V.; Veeraiah, N.; Piasecki, M.
2016-07-01
This study is mainly focused on enriching the UVB 311 narrow emission band of Gd3+ ions in Li2Osbnd PbOsbnd P2O5 glasses doped with 1.0 mol% of Gd2O3 and mixed with different concentrations of SnO2 (0-7.0 mol%). The emission spectra SnO2 free glasses exhibited intense narrow UVB band at 311 nm due to 6P7/2 → 8S7/2 transition of Gd3+ ions when excited at 273 nm. The intensity of this band is found to be enhanced nearly four times when the glasses are mixed with 3.0 mol% of SnO2. The reasons for this enhancement have been explored in the light of energy transfer from Sn4+ to Gd3+ ions with the help of rate equations. The declustering of Gd3+ ions (that reduce cross relaxation losses) by tin ions is also found to the other reason for such enrichment. The 311 nm radiation is an efficient in the treatment of various skin diseases and currently it is one of the most desirable and commonly utilised UVB in the construction of phototherapy devices.
NASA Astrophysics Data System (ADS)
Hall, Felix H. J.; Eberle, Pascal; Hegi, Gregor; Raoult, Maurice; Aymar, Mireille; Dulieu, Olivier; Willitsch, Stefan
2013-08-01
Cold chemical reactions between laser-cooled Ca+ ions and Rb atoms were studied in an ion-atom hybrid trap. Reaction rate constants were determined in the range of collision energies ⟨E coll⟩/k B=20 mK-20 K. The lowest energies were achieved in experiments using single localised Ca+ ions. Product branching ratios were studied using resonant-excitation mass spectrometry. The dynamics of the reactive processes in this system (non-radiative and radiative charge transfer as well as radiative association leading to the formation of CaRb+ molecular ions) have been analysed using high-level quantum-chemical calculations of the potential energy curves of CaRb+ and quantum-scattering calculations for the radiative channels. For the present low-energy scattering experiments, it is shown that the energy dependence of the reaction rate constants is governed by long-range interactions in line with the classical Langevin model, but their magnitude is determined by short-range non-adiabatic and radiative couplings which only weakly depend on the asymptotic energy. The quantum character of the collisions is predicted to manifest itself in the occurrence of narrow shape resonances at well-defined collision energies. The present results highlight both universal and system-specific phenomena in cold ion-neutral reactive collisions.
NASA Astrophysics Data System (ADS)
Dulieu, O.; Hall, F. H. J.; Eberle, P.; Hegi, G.; Raoult, M.; Aymar, M.; Willitsch, S.
2013-05-01
Cold chemical reactions between laser-cooled Ca+ or Ba+ ions and Rb atoms were studied in an ion-atom hybrid trap. Reaction rate constants were determined in the collision energy range Ecoll /kB = 20 mK-20 K. Product branching ratios were studied using resonant-excitation mass spectrometry. The dynamics of the reactive processes including the radiative formation of CaRb+ and BaRb+ molecular ions has been analyzed using accurate potential energy curves and quantum-scattering calculations for the radiative channels. It is shown that the energy dependence of the reaction rates is governed by long-range interactions, while its magnitude is determined by short-range non-adiabatic and radiative couplings. The quantum character of the collisions is predicted to manifest itself in the occurrence of narrow shape resonances at well-defined collision energies. The present results highlight both universal and system-specific phenomena in cold ion-neutral collisions. This work was supported by the Swiss National Science Foundation and the COST Action ''Ion Traps for Tomorrow's Applications''.
NASA Astrophysics Data System (ADS)
Kornbluth, Y. S.; Mathews, R. H.; Parameswaran, L.; Racz, L. M.; Velásquez-García, L. F.
2018-04-01
We report the design, modelling, and proof-of-concept demonstration of a continuously fed, atmospheric-pressure microplasma metal sputterer that is capable of printing conductive lines narrower than the width of the target without the need for post-processing or lithographic patterning. Ion drag-induced focusing is harnessed to print narrow lines; the focusing mechanism is modelled via COMSOL Multiphysics simulations and validated with experiments. A microplasma sputter head with gold target is constructed and used to deposit imprints with minimum feature sizes as narrow as 9 µm, roughness as small as 55 nm, and electrical resistivity as low as 1.1 µΩ · m.
A New Poisson-Nernst-Planck Model with Ion-Water Interactions for Charge Transport in Ion Channels.
Chen, Duan
2016-08-01
In this work, we propose a new Poisson-Nernst-Planck (PNP) model with ion-water interactions for biological charge transport in ion channels. Due to narrow geometries of these membrane proteins, ion-water interaction is critical for both dielectric property of water molecules in channel pore and transport dynamics of mobile ions. We model the ion-water interaction energy based on realistic experimental observations in an efficient mean-field approach. Variation of a total energy functional of the biological system yields a new PNP-type continuum model. Numerical simulations show that the proposed model with ion-water interaction energy has the new features that quantitatively describe dielectric properties of water molecules in narrow pores and are possible to model the selectivity of some ion channels.
High resolution energy analyzer for broad ion beam characterization
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kanarov, V.; Hayes, A.; Yevtukhov, R.
2008-09-15
analyzed IEDF shape or mean energy value. This led us to conclude that the optimized analyzer construction provides an energy resolution considerably narrower than the investigated ion beam energy spectrum full width at half maximum, and the derived energy spectrum is an objective and accurate representation of the analyzed broad ion beam energy distribution characteristics. A quantitative study of the focusing voltage and retarding grid field effects based on the experimental data and modeling results have supported this conclusion.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Holland, O.W.; El-Ghor, M.K.; White, C.W.
1989-01-01
Damage nucleation/growth in single-crystal Si during ion irradiation is discussed. For MeV ions, the rate of growth as well as the damage morphology are shown to vary widely along the track of the ion. This is attributed to a change in the dominant, defect-related reactions as the ion penetrates the crystal. The nature of these reactions were elucidated by studying the interaction of MeV ions with different types of defects. The defects were introduced into the Si crystal prior to high-energy irradiation by self-ion implantation at a medium energy (100 keV). Varied damage morphologies were produced by implanting different ionmore » fluences. Electron microscopy and ion-channeling measurements, in conjunction with annealing studies, were used to characterize the damage. Subtle changes in the predamage morphology are shown to result in markedly different responses to the high-energy irradiation, ranging from complete annealing of the damage to rapid growth. These divergent responses occur over a narrow range of dose (2--3 /times/ 10/sup 14/ cm/sup /minus/2/) of the medium-energy ions; this range also marks a transition in the growth behavior of the damage during the predamage implantation. A model is proposed which accounts for these observations and provides insight into ion-induced growth of amorphous layers in Si and the role of the amorphous/crystalline interface in this process. 15 refs, 9 figs.« less
Calculating tracer currents through narrow ion channels: Beyond the independent particle model.
Coalson, Rob D; Jasnow, David
2018-06-01
Discrete state models of single-file ion permeation through a narrow ion channel pore are employed to analyze the ratio of forward to backward tracer current. Conditions under which the well-known Ussing formula for this ratio hold are explored in systems where ions do not move independently through the channel. Building detailed balance into the rate constants for the model in such a way that under equilibrium conditions (equal rate of forward vs. backward permeation events) the Nernst Equation is satisfied, it is found that in a model where only one ion can occupy the channel at a time, the Ussing formula is always obeyed for any number of binding sites, reservoir concentrations of the ions and electric potential difference across the membrane which the ion channel spans, independent of the internal details of the permeation pathway. However, numerical analysis demonstrates that when multiple ions can occupy the channel at once, the nonequilibrium forward/backward tracer flux ratio deviates from the prediction of the Ussing model. Assuming an appropriate effective potential experienced by ions in the channel, we provide explicit formulae for the rate constants in these models. © 2018 IOP Publishing Ltd.
ARCS 3 ionospheric artificial argon ion beam injections - Waves near the heavy ion gyrofrequencies
NASA Technical Reports Server (NTRS)
Erlandson, R. E.; Cahill, L. J., Jr.; Kaufmann, R. L.; Arnoldy, R. L.; Pollock, C. J.
1989-01-01
Low-frequency electric field data below the proton gyrofrequency are presented for the duration of the argon ion beam experiment conducted as part of the Argon Release for Controlled Studies (ARCS) program. An argon ion beam was injected from the subpayload antiparallel or perpendicular to the magnetic field at altitudes from 250 to 405 km. During the injections, the wave spectra were broadband near the subpayload and narrow-band near heavy ion gyrofrequencies at perpendicular separation distances between 42 and 254 m. It is suggested that the narrow-band waves are associated with both the perpendicular argon ion beam and an unexpected flux of low-energy ions which peaked in energy near 15 eV and pitch angle near 90 deg with respect to the magnetic field.
Heavy-ion dominance near Cluster perigees
NASA Astrophysics Data System (ADS)
Ferradas, C. P.; Zhang, J.-C.; Kistler, L. M.; Spence, H. E.
2015-12-01
Time periods in which heavy ions dominate over H+ in the energy range of 1-40 keV were observed by the Cluster Ion Spectrometry (CIS)/COmposition DIstribution Function (CODIF) instrument onboard Cluster Spacecraft 4 at L values less than 4. The characteristic feature is a narrow flux peak at around 10 keV that extends into low L values, with He+ and/or O+ dominating. In the present work we perform a statistical study of these events and examine their temporal occurrence and spatial distribution. The observed features, both the narrow energy range and the heavy-ion dominance, can be interpreted using a model of ion drift from the plasma sheet, subject to charge exchange losses. The narrow energy range corresponds to the only energy range that has direct drift access from the plasma sheet during quiet times. The drift time to these locations from the plasma sheet is > 30 h, so that charge exchange has a significant impact on the population. We show that a simple drift/loss model can explain the dependence on L shell and MLT of these heavy-ion-dominant time periods.
NASA Astrophysics Data System (ADS)
Cayzac, W.; Pomorski, M.; Blažević, A.; Canaud, B.; Deslandes, D.; Fariaut, J.; Gontier, D.; Lescoute, E.; Marmouget, J. G.; Occelli, F.; Oudot, G.; Reverdin, C.; Sauvestre, J. E.; Sollier, A.; Soullié, G.; Varignon, C.; Villette, B.
2018-05-01
Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 μm and a spacing of 500 μm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 μg/cm2 thick carbon foil as an energy-loss target and a 2 m time-of-flight distance. This allows a highly precise beam energy measurement of δE/E ≈ 0.04%-0.2% and a resolution on the energy loss of 0.6%-2.5% for a fine testing of stopping-power models.
NASA Astrophysics Data System (ADS)
Chaban, R.; Pace, D. C.; Marcy, G. R.; Taussig, D.
2016-10-01
Energetic ion losses must be minimized in burning plasmas to maintain fusion power, and existing tokamaks provide access to energetic ion parameter regimes that are relevant to burning machines. A new Fast Ion Loss Detector (FILD) probe on the DIII-D tokamak has been optimized to resolve beam ion losses across a range of 30 - 90 keV in energy and 40° to 80° in pitch angle, thereby providing valuable measurements during many different experiments. The FILD is a magnetic spectrometer; once inserted into the tokamak, the magnetic field allows energetic ions to pass through a collimating aperture and strike a scintillator plate that is imaged by a wide view camera and narrow view photomultiplier tubes (PMTs). The design involves calculating scintillator strike patterns while varying probe geometry. Calculated scintillator patterns are then used to design an optical system that allows adjustment of the focus regions for the 1 MS/s resolved PMTs. A synthetic diagnostic will be used to determine the energy and pitch angle resolution that can be attained in DIII-D experiments. Work supported in part by US DOE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698.
Radio frequency sustained ion energy
Jassby, Daniel L.; Hooke, William M.
1977-01-01
Electromagnetic (E.M.) energy injection method and apparatus for producing and sustaining suprathermal ordered ions in a neutral, two-ion-species, toroidal, bulk equilibrium plasma. More particularly, the ions are produced and sustained in an ordered suprathermal state of existence above the average energy and velocity of the bulk equilibrium plasma by resonant rf energy injection in resonance with the natural frequency of one of the ion species. In one embodiment, the electromagnetic energy is injected to clamp the energy and velocity of one of the ion species so that the ion energy is increased, sustained, prolonged and continued in a suprathermal ordered state of existence containing appreciable stored energy that counteracts the slowing down effects of the bulk equilibrium plasma drag. Thus, selective deuteron absorption may be used for ion-tail creation by radio-frequency excitation alone. Also, the rf can be used to increase the fusion output of a two-component neutral injected plasma by selective heating of the injected deuterons.
Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass
Masai, Hirokazu; Yamada, Yasuhiro; Suzuki, Yuto; Teramura, Kentaro; Kanemitsu, Yoshihiko; Yoko, Toshinobu
2013-01-01
Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and formability. However, photoluminescence dynamics of ns2-type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn2+-doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S1-S0 transition and a slower T1-S0 relaxation, and also that the energy difference between T1 and S1 states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S1 and T1 states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors. PMID:24345869
Very-low-energy-spread ion sources
NASA Astrophysics Data System (ADS)
Lee, Y.
1997-05-01
Ion beams with low axial energy spread are required in many applications such as ion projection lithography, isobaric separation in radioactive ion beam experiments, and ion beam deposition processes. In an ion source, the spread of the axial ion energy is caused by the nonuniformity of the plasma potential distribution along the source axis. Multicusp ion sources are capable of production positive and negative ions with good beam quality and relatively low energy spread. By intorducing a magnetic filter inside the multicusp source chamber, the axial plasma potential distribution is modified and the energy spread of positive hydrogen ions can be reduced to as low as 1 eV. The energy spread measurements of multicusp sources have been conducted by employing three different techniques: an electrostatic energy analyzer at the source exit; a magnetic deflection spectrometer; and a retarding-field energy analyzer for the accelerated beam. These different measurements confirmed tha! t ! the axial energy spread of positive and negative ions generated in the filter-equipped multicusp sources are small. New ion source configurations are now being investigated at LBNL with the purpose of achieving enen lower energy spread (<1eV) and of maximizing source performance such as reliability and lifetime.
Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas
Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; Hamilton, Christopher E.; Santiago, Miguel A.; Kreuzer, Christian; Sefkow, Adam B.; Shah, Rahul C.; Fernández, Juan C.
2015-01-01
Table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ∼5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (∼1012 V m−1) and magnetic (∼104 T) fields. These results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science. PMID:26657147
Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas
Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; ...
2015-12-11
Here, table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ~5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (~10 12 V m –1) and magnetic (~10 4 T)more » fields. These results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science.« less
Charging dynamics of supercapacitors with narrow cylindrical nanopores.
Lee, Alpha A; Kondrat, Svyatoslav; Oshanin, Gleb; Kornyshev, Alexei A
2014-08-08
We present a coarse-grained, continuum kinetic theory for charging supercapacitors with narrow cylindrical nanopores. The theory reveals that the occupancy of a nonpolarized pore and the energy barrier for ion-ion interdiffusion are the key issues controlling the different regimes of dynamic response. For 'ionophobic' pores, where the pore is empty at no applied voltage, charge density advances into the pore via diffusion-like dynamics. The mechanism of charging an 'ionophilic' pore is starkly different: for moderate ionophilicities, co-ions are expelled from the pore in a front-like manner, with significant 'congestion' at the pore entrance predicted for strong ionophilicity. We thus show that pore ionophilicity is detrimental to the speed of charging/discharging cycles, whereas making pores more ionophobic can substantially accelerate charging and cyclic recharging.
Charging dynamics of supercapacitors with narrow cylindrical nanopores
NASA Astrophysics Data System (ADS)
Lee, Alpha A.; Kondrat, Svyatoslav; Oshanin, Gleb; Kornyshev, Alexei A.
2014-08-01
We present a coarse-grained, continuum kinetic theory for charging supercapacitors with narrow cylindrical nanopores. The theory reveals that the occupancy of a nonpolarized pore and the energy barrier for ion-ion interdiffusion are the key issues controlling the different regimes of dynamic response. For ‘ionophobic’ pores, where the pore is empty at no applied voltage, charge density advances into the pore via diffusion-like dynamics. The mechanism of charging an ‘ionophilic’ pore is starkly different: for moderate ionophilicities, co-ions are expelled from the pore in a front-like manner, with significant ‘congestion’ at the pore entrance predicted for strong ionophilicity. We thus show that pore ionophilicity is detrimental to the speed of charging/discharging cycles, whereas making pores more ionophobic can substantially accelerate charging and cyclic recharging.
Neutral beamline with improved ion energy recovery
Dagenhart, William K.; Haselton, Halsey H.; Stirling, William L.; Whealton, John H.
1984-01-01
A neutral beamline generator with unneutralized ion energy recovery is provided which enhances the energy recovery of the full energy ion component of the beam exiting the neutralizer cell of the beamline. The unneutralized full energy ions exiting the neutralizer are deflected from the beam path and the electrons in the cell are blocked by a magnetic field applied transverse to the beamline in the cell exit region. The ions, which are generated at essentially ground potential and accelerated through the neutralizer cell by a negative acceleration voltage, are collected at ground potential. A neutralizer cell exit end region is provided which allows the magnetic and electric fields acting on the exiting ions to be closely coupled. As a result, the fractional energy ions exiting the cell with the full energy ions are reflected back into the gas cell. Thus, the fractional energy ions do not detract from the energy recovery efficiency of full energy ions exiting the cell which can reach the ground potential interior surfaces of the beamline housing.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Weber, M.J.; Brawer, S.A.
1982-07-02
The local structure at individual ion sites in simple and multicomponent glasses is simulated using methods of molecular dynamics. Computer simulations of fluoroberyllate glasses predict a range of ion separations and coordination numbers that increases with increasing complexity of the glass composition. This occurs at both glass forming and glass modifying cation sites. Laser-induced fluorescence line-narrowing techniques provide a unique probe of the local environments of selected subsets of ions and are used to measure site to site variations in the electronic energy levels and transition probabilities of rare earth ions. These and additional results from EXAFS, neutron and x-raymore » diffraction, and NMR experiments are compared with simulated glass structures.« less
Dielectric Self-Energy in Poisson-Boltzmann and Poisson-Nernst-Planck Models of Ion Channels
Corry, Ben; Kuyucak, Serdar; Chung, Shin-Ho
2003-01-01
We demonstrated previously that the two continuum theories widely used in modeling biological ion channels give unreliable results when the radius of the conduit is less than two Debye lengths. The reason for this failure is the neglect of surface charges on the protein wall induced by permeating ions. Here we attempt to improve the accuracy of the Poisson-Boltzmann and Poisson-Nernst-Planck theories, when applied to channel-like environments, by including a specific dielectric self-energy term to overcome spurious shielding effects inherent in these theories. By comparing results with Brownian dynamics simulations, we show that the inclusion of an additional term in the equations yields significant qualitative improvements. The modified theories perform well in very wide and very narrow channels, but are less successful at intermediate sizes. The situation is worse in multi-ion channels because of the inability of the continuum theories to handle the ion-to-ion interactions correctly. Thus, further work is required if these continuum theories are to be reliably salvaged for quantitative studies of biological ion channels in all situations. PMID:12770869
DOE Office of Scientific and Technical Information (OSTI.GOV)
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 createdmore » 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.« less
NASA Technical Reports Server (NTRS)
Behar, Ehud; Nordon, Raanan; Soker, Noam; Kastner, Joel H.; Yu, Young Sam
2009-01-01
X-rays from planetary nebulae (PNs) are believed to originate from a shock driven into the fast stellar wind (v 1000 kilometers per second) as it collides with an earlier circumstellar slow wind (v 10 kilometers per second). In theory, the shocked fast wind (hot hubble) and the ambient cold nebula can remain separated by magnetic fields along a surface referred to as the contact discontinuity (CD) that inhibits diffusion and heat conduction. The CD region is extremely difficult to probe directly owing to its small size and faint emission. This has largely left the study of CDs, stellar-shocks, and the associated micro-physics in the realm of theory. This paper presents spectroscopic evidence for ions from the hot bubble (kT approximately equal to 100 eV) crossing the CD and penetrating the cold nebular gas (kT approximately equal to 1 eV). Specifically, a narrow radiative recombination continuum (RRC) emission feature is identified in the high resolution X-ray spectrum of the PN BD+30degree3639 indicating bare C VII ions are recombining with cool electrons at kT(sub e) = 1.7 plus or minus 1.3 eV. An upper limit to the flux of the narrow RRC of H-like C VI is obtained as well. The RRCs are interpreted as due to C ions from the hot bubble of BD+30degree3639 crossing the CD into the cold nebula, where they ultimately recombine with its cool electrons. The RRC flux ratio of C VII to C VI constrains the temperature jump across the CD to deltakT greater than 80 eV, providing for the first time direct evidence for the stark temperature disparity between the two sides of an astrophysical CD, and constraining the role of magnetic fields and heat conduction accordingly. Two colliding-wind binaries are noted to have similar RRCs suggesting a temperature jump and CD crossing by ions may be common feature of stellar wind shocks.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Diomede, Paola; Economou, Demetre J.; Donnelly, Vincent M.
2011-04-15
A Particle-in-Cell simulation with Monte Carlo Collisions (PIC-MCC) was conducted of the application of tailored DC voltage steps on an electrode, during the afterglow of a capacitively-coupled pulsed-plasma argon discharge, to control the energy of ions incident on the counter-electrode. Staircase voltage waveforms with selected amplitudes and durations resulted in ion energy distributions (IED) with distinct narrow peaks, with controlled energies and fraction of ions under each peak. Temporary electron heating at the moment of application of a DC voltage step did not influence the electron density decay in the afterglow. The IED peaks were 'smeared' by collisions, especially atmore » the higher pressures of the range (10-40 mTorr) investigated.« less
Production of High Energy Ions Near an Ion Thruster Discharge Hollow Cathode
NASA Technical Reports Server (NTRS)
Katz, Ira; Mikellides, I. G.; Goebel, D. M.; Jameson, K. K.; Wirz, R.; Polk, James E.
2006-01-01
Several researchers have measured ions leaving ion thruster discharge chambers with energies far greater than measured discharge chamber potentials. Presented in this paper is a new mechanism for the generation of high energy ions and a comparison with measured ion spectra. The source of high energy ions has been a puzzle because they not only have energies in excess of measured steady state potentials, but as reported by Goebel et. al. [1], their flux is independent of the amplitude of time dependent plasma fluctuations. The mechanism relies on the charge exchange neutralization of xenon ions accelerated radially into the potential trough in front of the discharge cathode. Previous researchers [2] have identified the importance of charge exchange in this region as a mechanism for protecting discharge cathode surfaces from ion bombardment. This paper is the first to identify how charge exchange in this region can lead to ion energy enhancement.
Ion acceleration in shell cylinders irradiated by a short intense laser pulse
DOE Office of Scientific and Technical Information (OSTI.GOV)
Andreev, A.; ELI-ALPS, Szeged; Platonov, K.
The interaction of a short high intensity laser pulse with homo and heterogeneous shell cylinders has been analyzed using particle-in-cell simulations and analytical modeling. We show that the shell cylinder is proficient of accelerating and focusing ions in a narrow region. In the case of shell cylinder, the ion energy exceeds the ion energy for a flat target of the same thickness. The constructed model enables the evaluation of the ion energy and the number of ions in the focusing region.
Neutral beamline with improved ion energy recovery
Kim, Jinchoon
1984-01-01
A neutral beamline employing direct energy recovery of unneutralized residual ions is provided which enhances the energy recovery of the full energy ion component of the beam exiting the neutralizer cell, and thus improves the overall neutral beamline efficiency. The unneutralized full energy ions exiting the neutralizer are deflected from the beam path and the electrons in the cell are blocked by a magnetic field applied transverse to the beam direction in the neutral izer exit region. The ions which are generated at essentially ground potential and accelerated through the neutralizer cell by a negative acceleration voltage are collected at ground potential. A neutralizer cell exit end region is provided which allows the magnetic and electric fields acting on the exiting ions to be loosely coupled. As a result, the fractional energy ions exiting the cell are reflected onto and collected at an interior wall of the neutralizer formed by the modified end geometry, and thus do not detract from the energy recovery efficiency of full energy ions exiting the cell. Electrons within the neutralizer are prevented from exiting the neutralizer end opening by the action of crossed fields drift (ExB) and are terminated to a collector collar around the downstream opening of the neutralizer. The correct combination of the extended neutralizer end structure and the magnet region is designed so as to maximize the exit of full energy ions and to contain the fractional energy ions.
Optimized Ion Energy Profiles for Heavy Ion Direct Drive Targets
NASA Astrophysics Data System (ADS)
Hay, Michael J.; Barnard, John J.; Perkins, L. John; Logan, B. Grant
2009-11-01
Recent 1-D implosion calculations [1] have characterized pure-DT targets delivering gains of 50-90 with less than 0.5 MJ of heavy ion direct drive. With a payload fraction of 1/3, these low-aspect ratio targets operate near the peak of rocket efficiency and achieve ˜10% overall coupling efficiencies (vs. the 15-20% efficiencies analytically predicted for less stable, higher-aspect ratio targets). In Ref. 1, the ion energy is ramped directly from a 50 MeV foot pulse to a 500 MeV main pulse. In this paper, we instead tune the ion energy throughout the drive to closely match the beam deposition with the inward progress of the ablation front. We will present the ion energy and intensity time histories that maximize drive efficiency and gain for a single target at constant integrated drive energy. [1] L. J. Perkins, B. G. Logan, J. J. Barnard, and M. J. Hay. ``High Efficiency High Gain Heavy Ion Direct Drive Targets,'' Bulletin of the American Physical Society, vol. 54: DPP, Nov. 2009.
NASA Astrophysics Data System (ADS)
Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald; Hamilton, Christopher; Santiago, Miguel; Kreuzer, Christian; Shah, Rahul; Fernandez, Juan; Los Alamos National Laboratory Team; Ludwig-Maximilian-University Team
2015-11-01
Table-top laser-plasma ion accelerators seldom achieve narrow energy spreads, and never without serious compromises in efficiency, particle yield, etc. Using massive computer simulations, we identify a self-organizing scheme that exploits persisting self-generated plasma electric (~ TV/m) and magnetic (~ 104 Tesla) fields to reduce the ion energy spread after the laser exits the plasma - separating the ion acceleration from the energy spread reduction. Consistent with the scheme, we experimentally demonstrate aluminum and carbon ion beams with narrow spectral peaks at energies up to 310 MeV (11.5 MeV/nucleon) and 220 MeV (18.3 MeV/nucleon), respectively, with high conversion efficiency (~ 5%, i.e., 4J out of 80J laser). This is achieved with 0.12 PW high-contrast Gaussian laser pulses irradiating planar foils with optimal thicknesses of up to 250 nm that scale with laser intensity. When increasing the focused laser intensity fourfold (by reducing the focusing optic f/number twofold), the spectral-peak energy increases twofold. These results pave the way for next generation compact accelerators suitable for applications. For example, 400 MeV (33.3 MeV/nucleon) carbon-ion beam with narrow energy spread required for ion fast ignition could be generated using PW-class lasers.
Kinetic energy offsets for multicharged ions from an electron beam ion source.
Kulkarni, D D; Ahl, C D; Shore, A M; Miller, A J; Harriss, J E; Sosolik, C E; Marler, J P
2017-08-01
Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar 4+ and Ar 8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.
Aumayr, Friedrich; Facsko, Stefan; El-Said, Ayman S; Trautmann, Christina; Schleberger, Marika
2011-10-05
This topical review focuses on recent advances in the understanding of the formation of surface nanostructures, an intriguing phenomenon in ion-surface interaction due to the impact of individual ions. In many solid targets, swift heavy ions produce narrow cylindrical tracks accompanied by the formation of a surface nanostructure. More recently, a similar nanometric surface effect has been revealed for the impact of individual, very slow but highly charged ions. While swift ions transfer their large kinetic energy to the target via ionization and electronic excitation processes (electronic stopping), slow highly charged ions produce surface structures due to potential energy deposited at the top surface layers. Despite the differences in primary excitation, the similarity between the nanostructures is striking and strongly points to a common mechanism related to the energy transfer from the electronic to the lattice system of the target. A comparison of surface structures induced by swift heavy ions and slow highly charged ions provides a valuable insight to better understand the formation mechanisms. © 2011 IOP Publishing Ltd
Synergy of elastic and inelastic energy loss on ion track formation in SrTiO 3
DOE Office of Scientific and Technical Information (OSTI.GOV)
Weber, William J.; Zarkadoula, Eva; Pakarinen, Olli H.
2015-01-12
While the interaction of energetic ions with solids is well known to result in inelastic energy loss to electrons and elastic energy loss to atomic nuclei in the solid, the coupled effects of these energy losses on defect production, nanostructure evolution and phase transformations in ionic and covalently bonded materials are complex and not well understood due to dependencies on electron-electron scattering processes, electron-phonon coupling, localized electronic excitations, diffusivity of charged defects, and solid-state radiolysis. Here we show that a colossal synergy occurs between inelastic energy loss and pre-existing atomic defects created by elastic energy loss in single crystal strontiummore » titanate (SrTiO 3), resulting in the formation of nanometer-sized amorphous tracks, but only in the narrow region with pre-existing defects. These defects locally decrease the electronic and atomic thermal conductivities and increase electron-phonon coupling, which locally increase the intensity of the thermal spike for each ion. This work identifies a major gap in understanding on the role of defects in electronic energy dissipation and electron-phonon coupling; it also provides insights for creating novel interfaces and nanostructures to functionalize thin film structures, including tunable electronic, ionic, magnetic and optical properties.« less
Measurement of ultra-low ion energy of decelerated ion beam using a deflecting electric field
NASA Astrophysics Data System (ADS)
Thopan, P.; Suwannakachorn, D.; Tippawan, U.; Yu, L. D.
2015-12-01
In investigation on ultra-low-energy ion bombardment effect on DNA, an ion beam deceleration lens was developed for high-quality ultra-low-energy ion beam. Measurement of the ion energy after deceleration was necessary to confirm the ion beam really decelerated as theoretically predicted. In contrast to conventional methods, this work used a simple deflecting electrostatic field after the deceleration lens to bend the ion beam. The beam bending distance depended on the ion energy and was described and simulated. A system for the measurement of the ion beam energy was constructed. It consisted of a pair of parallel electrode plates to generate the deflecting electrical field, a copper rod measurement piece to detect ion beam current, a vernier caliper to mark the beam position, a stepping motor to translate the measurement rod, and a webcam-camera to read the beam bending distance. The entire system was installed after the ion-beam deceleration lens inside the large chamber of the bioengineering vertical ion beam line. Moving the measurement rod across the decelerated ion beam enabled to obtain beam profiles, from which the beam bending distance could be known and the ion beam energy could be calculated. The measurement results were in good agreement with theoretical and simulated results.
Electron energy recovery system for negative ion sources
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.
Energy-banded ions in Saturn's magnetosphere
NASA Astrophysics Data System (ADS)
Thomsen, M. F.; Badman, S. V.; Jackman, C. M.; Jia, X.; Kivelson, M. G.; Kurth, W. S.
2017-05-01
Using data from the Cassini Plasma Spectrometer ion mass spectrometer, we report the first observation of energy-banded ions at Saturn. Observed near midnight at relatively high magnetic latitudes, the banded ions are dominantly H+, and they occupy the range of energies typically associated with the thermal pickup distribution in the inner magnetosphere (L < 10), but their energies decline monotonically with increasing radial distance (or time or decreasing latitude). Their pitch angle distribution suggests a source at low (or slightly southern) latitudes. The band energies, including their pitch angle dependence, are consistent with a bounce-resonant interaction between thermal H+ ions and the standing wave structure of a field line resonance. There is additional evidence in the pitch angle dependence of the band energies that the particles in each band may have a common time of flight from their most recent interaction with the wave, which may have been at slightly southern latitudes. Thus, while the particles are basically bounce resonant, their energization may be dominated by their most recent encounter with the standing wave.
An electron cyclotron resonance ion source based low energy ion beam platform.
Sun, L T; Shang, Y; Ma, B H; Zhang, X Z; Feng, Y C; Li, X X; Wang, H; Guo, X H; Song, M T; Zhao, H Y; Zhang, Z M; Zhao, H W; Xie, D Z
2008-02-01
To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.
Mean excitation energies for molecular ions
NASA Astrophysics Data System (ADS)
Jensen, Phillip W. K.; Sauer, Stephan P. A.; Oddershede, Jens; Sabin, John R.
2017-03-01
The essential material constant that determines the bulk of the stopping power of high energy projectiles, the mean excitation energy, is calculated for a range of smaller molecular ions using the RPA method. It is demonstrated that the mean excitation energy of both molecules and atoms increase with ionic charge. However, while the mean excitation energies of atoms also increase with atomic number, the opposite is the case for mean excitation energies for molecules and molecular ions. The origin of these effects is explained by considering the spectral representation of the excited state contributing to the mean excitation energy.
Low energy ion beam dynamics of NANOGAN ECR ion source
NASA Astrophysics Data System (ADS)
Kumar, Sarvesh; Mandal, A.
2016-04-01
A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.
Interaction between Low Energy Ions and the Complicated Organism
NASA Astrophysics Data System (ADS)
Yu, Zeng-liang
1999-12-01
Low energy ions exist widely in natural world, but people pay a little attention on the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in chemical synthesis of the biomolecules and application in genetic modification.
Low-energy ion outflow modulated by the solar wind energy input
NASA Astrophysics Data System (ADS)
Li, Kun; Wei, Yong; Andre, Mats; Eriksson, Anders; Haaland, Stein; Kronberg, Elena; Nilsson, Hans; Maes, Lukas
2017-04-01
Due to the spacecraft charging issue, it has been difficult to measure low-energy ions of ionospheric origin in the magnetosphere. A recent study taking advantage of the spacecraft electric potential has found that the previously 'hidden' low-energy ions is dominant in the magnetosphere. This comprehensive dataset of low-energy ions allows us to study the relationship between the ionospheric outflow and energy input from the solar wind (ɛ). In this study, we discuss the ratios of the solar wind energy input to the energy of the ionospheric outflow. We show that the ɛ controls the ionospheric outflow when the ɛ is high, while the ionospheric outflow does not systematically change with the ɛ when the ɛ is low.
Ion energy/momentum effects during ion assisted growth of niobium nitride films
NASA Astrophysics Data System (ADS)
Klingenberg, Melissa L.
The research described herein was performed to better understand and discern ion energy vs. ion momentum effects during ion beam assisted (IBAD) film growth and their effects on residual stress, crystalline structure, morphology, and composition, which influence film tribological properties. NbxN y was chosen for this research because it is a refractory material that can possess a large number of crystalline structures, and it has been found to have good tribological properties. To separate the effects of momentum transfer per arriving atom (p/a), which considers bombarding species mass, energy, and ion-to-atom transport ratio, from those of energy deposition per arriving atom (E/a), a mass independent parameter, different inert ion beams (krypton, argon, and neon) were used to create a matrix of coatings formed using similar energy deposition, but different momentum transfer and vice versa. Deposition was conducted in a research-scale IBAD system using electron beam evaporation, a radio frequency ion source, and a neutral nitrogen gas backfill. Films were characterized using x-ray diffraction, atomic force microscopy, Rutherford backscattering spectrometry, and residual stress analysis. Direct and quantifiable effects of bombardment were observed; however, energy deposition and momentum transfer effects could not be completely separated, confirming that thin film processes are complex. Complexities arose from ion-specific interactions (ion size, recoil energy, per cent reflected neutrals, Penning ionization, etc.) and chemistry effects that are not considered by the simple models. Overall, it can be stated that bombardment promoted nitride formation, nanocrystallinity, and compressive stress formation; influenced morphology (which influenced post-deposition oxygen uptake) and stress evolution; increased lattice parameter; modified crystalline phase and texture; and led to inert gas incorporation. High stress levels correlated strongly with material disorder and
Kisley, Lydia; Chen, Jixin; Mansur, Andrea P.; Dominguez-Medina, Sergio; Kulla, Eliona; Kang, Marci; Shuang, Bo; Kourentzi, Katerina; Poongavanam, Mohan-Vivekanandan; Dhamane, Sagar; Willson, Richard C.; Landes, Christy F.
2014-01-01
The retention and elution of proteins in ion-exchange chromatography is routinely controlled by adjusting the mobile phase salt concentration. It has repeatedly been observed, as judged from adsorption isotherms, that the apparent heterogeneity of adsorption is lower at more-eluting, higher ionic strength. Here, we present an investigation into the mechanism of this phenomenon using a single-molecule, super-resolution imaging technique called motion-blur Points Accumulation for Imaging in Nanoscale Topography (mbPAINT). We observed that the number of functional adsorption sites was smaller at high ionic strength and that these sites had reduced desorption kinetic heterogeneity, and thus narrower predicted elution profiles, for the anion-exchange adsorption of α-lactalbumin on an agarose-supported, clustered-charge ligand stationary phase. Explanations for the narrowing of the functional population such as inter-protein interactions and protein or support structural changes were investigated through kinetic analysis, circular dichroism spectroscopy, and microscopy of agarose microbeads, respectively. The results suggest the reduction of heterogeneity is due to both electrostatic screening between the protein and ligand and tuning the steric availability within the agarose support. Overall, we have shown that single molecule spectroscopy can aid in understanding the influence of ionic strength on the population of functional adsorbent sites participating in the ion-exchange chromatographic separation of proteins. PMID:24751557
NASA Astrophysics Data System (ADS)
Tsuji, H.; Arai, N.; Ueno, K.; Matsumoto, T.; Gotoh, N.; Adachi, K.; Kotaki, H.; Gotoh, Y.; Ishikawa, J.
2006-01-01
Mono-layered gold nanoparticles just below the surface of silicon oxide film have been formed by a gold negative-ion implantation at a very low-energy, where the deviation of implanted atoms was sufficiently narrow comparing to the size of nanoparticles. Gold negative ions were implanted into SiO2 thin films on Si substrate at energies of 35, 15 and 1 keV. The samples were annealed in Ar flow for 1 h at 900 or 1000 °C. Cross-sectional TEM observation for the implantation at 1 keV showed existence of Au nanoparticles aligned in the same depth of 5 nm from the surface. The nanoparticles had almost same diameter of 7 nm. The nanoparticles were found to be gold single crystal from a high-resolution TEM image.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Rosen, Johanna; Anders, Andre; Mraz, Stanislav
2006-03-23
The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as wellmore » as a narrow IED. These data may enable tailoring thin-film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.« less
Rechargeable dual-metal-ion batteries for advanced energy storage.
Yao, Hu-Rong; You, Ya; Yin, Ya-Xia; Wan, Li-Jun; Guo, Yu-Guo
2016-04-14
Energy storage devices are more important today than any time before in human history due to the increasing demand for clean and sustainable energy. Rechargeable batteries are emerging as the most efficient energy storage technology for a wide range of portable devices, grids and electronic vehicles. Future generations of batteries are required to have high gravimetric and volumetric energy, high power density, low price, long cycle life, high safety and low self-discharge properties. However, it is quite challenging to achieve the above properties simultaneously in state-of-the-art single metal ion batteries (e.g. Li-ion batteries, Na-ion batteries and Mg-ion batteries). In this contribution, hybrid-ion batteries in which various metal ions simultaneously engage to store energy are shown to provide a new perspective towards advanced energy storage: by connecting the respective advantages of different metal ion batteries they have recently attracted widespread attention due to their novel performances. The properties of hybrid-ion batteries are not simply the superposition of the performances of single ion batteries. To enable a distinct description, we only focus on dual-metal-ion batteries in this article, for which the design and the benefits are briefly discussed. We enumerate some new results about dual-metal-ion batteries and demonstrate the mechanism for improving performance based on knowledge from the literature and experiments. Although the search for hybrid-ion batteries is still at an early age, we believe that this strategy would be an excellent choice for breaking the inherent disadvantages of single ion batteries in the near future.
Influence of the narrow {111} planes on axial and planar ion channeling.
Motapothula, M; Dang, Z Y; Venkatesan, T; Breese, M B H; Rana, M A; Osman, A
2012-05-11
We report channeling patterns where clearly resolved effects of the narrow {111} planes are observed in axial and planar alignments for 2 MeV protons passing through a 55 nm [001] silicon membrane. At certain axes, such as <213> and <314>, the offset in atomic rows forming the narrow {111} planes results in shielding from the large potential at the wide {111} planes, producing a region of shallow, asymmetric potential from which axial channeling patterns have no plane of symmetry. At small tilts from such axes, different behavior is observed from the wide and narrow {111} planes. At planar alignment, distinctive channeling effects due to the narrow planes are observed. As a consequence of the shallow potential well at the narrow planes, incident protons suffer dechanneled trajectories which are excluded from channeling within the wide planes, resulting in an anomalously large scattered beam at {111} alignment.
Surface modification using low energy ground state ion beams
NASA Technical Reports Server (NTRS)
Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)
1990-01-01
A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux, and energy is presented. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation. One area of application is in the manufacture of semiconductor devices from semiconductor wafers.
High responsivity secondary ion energy analyzer
NASA Astrophysics Data System (ADS)
Belov, A. S.; Chermoshentsev, D. A.; Gavrilov, S. A.; Frolov, O. T.; Netchaeva, L. P.; Nikulin, E. S.; Zubets, V. N.
2018-05-01
The degree of space charge compensation of a 70 mA, 400 keV pulsed hydrogen ion beam has been measured with the use of an electrostatic energy analyzer of secondary ions. The large azimuthal angle of the analyzer enables a high responsivity, defined as the ratio of the slow secondary ion current emerging from the partially-compensated ion beam to the fast ion beam current. We measured 84% space charge compensation of the ion beam. The current from the slow ions and the rise time from the degree of space charge compensation were measured and compared with expected values.
NASA Astrophysics Data System (ADS)
Paty, C.; Paterson, W.; Winglee, R.
2008-06-01
We investigate the ion population and energy distribution within Ganymede's magnetosphere by examining Ganymede's ionospheric outflow as a source of heavy (O+) and light (H+) ions and the Jovian magnetospheric plasma as an external source of heavy ions. We develop a method for examining the energy distributions of each ion species in a three-dimensional multifluid simulation in a way directly comparable to the observations of the Plasma Experiment on the Galileo spacecraft. This is used to provide new insight to the existing controversy over the composition of Ganymede's observed ionospheric outflow, and enables further examination of the energetic signatures of the ion population trapped within Ganymede's magnetosphere. The model-predicted ionospheric outflow is consistent with the in situ ion energy spectrograms observed by the Galileo Plasma Experiment at closest approach, and requires that both ionospheric H+ and O+ are present in the population of ions exiting Ganymede's ionosphere over the polar cap. The outward flux of ionospheric ions was calculated to be ~1026 ions/cm2/s, which is in agreement with independently calculated sputtering rates of Ganymede's icy surface. The modeled spectrograms define characteristic energy signatures and populations for various regions of Ganymede's magnetosphere, which illustrate the major sources of ions trapped within the magnetosphere are Ganymede's ionospheric O+ and H+. The fact that very little plasma was observed inside Ganymede's magnetosphere during the G8 flyby is attributed to the region being shadowed from the sun for ~60 h, which may indicate the importance of photoionization for sustaining Ganymede's ionospheric plasma source.
Price, W D; Williams, E R
1997-11-20
Unimolecular rate constants for blackbody infrared radiative dissociation (BIRD) were calculated for the model protonated peptide (AlaGly)(n) (n = 2-32) using a variety of dissociation parameters. Combinations of dissociation threshold energies ranging from 0.8 to 1.7 eV and transition entropies corresponding to Arrhenius preexponential factors ranging from very "tight" (A(infinity) = 10(9.9) s(-1)) to "loose" (A(infinity) = 10(16.8) s(-1)) were selected to represent dissociation parameters within the experimental temperature range (300-520 K) and kinetic window (k(uni) = 0.001-0.20 s(-1)) typically used in the BIRD experiment. Arrhenius parameters were determined from the temperature dependence of these values and compared to those in the rapid energy exchange (REX) limit. In this limit, the internal energy of a population of ions is given by a Boltzmann distribution, and kinetics are the same as those in the traditional high-pressure limit. For a dissociation process to be in this limit, the rate of photon exchange between an ion and the vacuum chamber walls must be significantly greater than the dissociation rate. Kinetics rapidly approach the REX limit either as the molecular size or threshold dissociation energy increases or as the transition-state entropy or experimental temperature decreases. Under typical experimental conditions, peptide ions larger than 1.6 kDa should be in the REX limit. Smaller ions may also be in the REX limit depending on the value of the threshold dissociation energy and transition-state entropy. Either modeling or information about the dissociation mechanism must be known in order to confirm REX limit kinetics for these smaller ions. Three principal factors that lead to the size dependence of REX limit kinetics are identified. With increasing molecular size, rates of radiative absorption and emission increase, internal energy distributions become relatively narrower, and the microcanonical dissociation rate constants increase more
Price, William D.
2005-01-01
Unimolecular rate constants for blackbody infrared radiative dissociation (BIRD) were calculated for the model protonated peptide (AlaGly)n (n = 2–32) using a variety of dissociation parameters. Combinations of dissociation threshold energies ranging from 0.8 to 1.7 eV and transition entropies corresponding to Arrhenius preexponential factors ranging from very “tight” (A∞ = 109.9 s−1) to “loose” (A∞ = 1016.8 s−1) were selected to represent dissociation parameters within the experimental temperature range (300–520 K) and kinetic window (kuni = 0.001–0.20 s−1) typically used in the BIRD experiment. Arrhenius parameters were determined from the temperature dependence of these values and compared to those in the rapid energy exchange (REX) limit. In this limit, the internal energy of a population of ions is given by a Boltzmann distribution, and kinetics are the same as those in the traditional high-pressure limit. For a dissociation process to be in this limit, the rate of photon exchange between an ion and the vacuum chamber walls must be significantly greater than the dissociation rate. Kinetics rapidly approach the REX limit either as the molecular size or threshold dissociation energy increases or as the transition-state entropy or experimental temperature decreases. Under typical experimental conditions, peptide ions larger than 1.6 kDa should be in the REX limit. Smaller ions may also be in the REX limit depending on the value of the threshold dissociation energy and transition-state entropy. Either modeling or information about the dissociation mechanism must be known in order to confirm REX limit kinetics for these smaller ions. Three principal factors that lead to the size dependence of REX limit kinetics are identified. With increasing molecular size, rates of radiative absorption and emission increase, internal energy distributions become relatively narrower, and the microcanonical dissociation rate constants increase more slowly
Ion-induced particle desorption in time-of-flight medium energy ion scattering
NASA Astrophysics Data System (ADS)
Lohmann, S.; Primetzhofer, D.
2018-05-01
Secondary ions emitted from solids upon ion impact are studied in a time-of-flight medium energy ion scattering (ToF-MEIS) set-up. In order to investigate characteristics of the emission processes and to evaluate the potential for surface and thin film analysis, experiments employing TiN and Al samples were conducted. The ejected ions exhibit a low initial kinetic energy of a few eV, thus, requiring a sufficiently high acceleration voltage for detection. Molecular and atomic ions of different charge states originating both from surface contaminations and the sample material are found, and relative yields of several species were determined. Experimental evidence that points towards a predominantly electronic sputtering process is presented. For emitted Ti target atoms an additional nuclear sputtering component is suggested.
Ion energy distributions in silane-hydrogen plasmas
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hamers, E.A.G.; Sark, W.G.J.H.M. van; Bezemer, J.
1996-12-31
For the first time ion energy distributions (IED) of different ions from silane-hydrogen (SiH{sub 4}-H{sub 2}) RF plasmas are presented, i.e., the distributions of SiH{sub 3}{sup +}, SiH{sub 2}{sup +} and Si{sub 2}H{sub 4}{sup +}. The energy distributions of SiH{sub 3}{sup +} and SiH{sub 2}{sup +} ions show peaks, which are caused by a charge exchange process in the sheath. A method is presented by which the net charge density in the sheath is determined from the plasma potential and the energy positions of the charge exchange peaks. Knowing the net charge density in the sheath and the plasma potential,more » the sheath thickness can be determined and an estimation of the absolute ion fluxes can be made. The flux of ions can, at maximum, account for 10% of the observed deposition rate.« less
Rajamani, Saravanan; Arora, Kanika; Konakov, Anton; Belov, Alexey; Korolev, Dmitry; Nikolskaya, Alyona; Mikhaylov, Alexey N; Surodin, Sergey; Kryukov, Ruslan; Nikolichev, Dmitri; Sushkov, Artem; Pavlov, Dmitry; Tetelbaum, David; Kumar, Mukesh; Kumar, Mahesh
2018-04-20
Semiconductor quantum dots (QDs) have attracted tremendous attention owing to their novel electrical and optical properties due to the size dependent quantum confinement effects. This provides an advantage of tunable wavelength detection, which is essential to realize spectrally selective photodetectors. We report the fabrication and characterization of high performance narrow band ultraviolet photodetector (UV-B) based on In2O3 nanocrystals embedded in Al2O3 matrices. The In2O3 nanocrystals are synthesized in Al2O3 matrix by sequential implantation of In+ and N2+ ions and post-implantation annealing. The photodetector exhibits excellent optoelectronic performances with high spectral responsivity and external quantum efficiency. The spectral response showed a band-selective nature with a full width half maximum of ∼ 60 nm, and the responsivity reaches up to 70 A/W under 290 nm at 5 V bias. The corresponding rejection ratio to visible region was as high as 8400. The high performance of this photodetector makes it highly suitable for practical applications such as narrow-band spectrum-selective photodetectors. The device design based on ion-synthesized nanocrystals would provide a new approach for realizing a visible-blind photodetector. © 2018 IOP Publishing Ltd.
Mono-energetic ions emission by nanosecond laser solid target irradiation
NASA Astrophysics Data System (ADS)
Muoio, A.; Tudisco, S.; Altana, C.; Lanzalone, G.; Mascali, D.; Cirrone, G. A. P.; Schillaci, F.; Trifirò, A.
2016-09-01
An experimental campaign aiming to investigate the acceleration mechanisms through laser-matter interaction in nanosecond domain has been carried out at the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS, Catania. Pure Al targets were irradiated by 6 ns laser pulses at different pumping energies, up to 2 J. Advanced diagnostics tools were used to characterize the plasma plume and ion production. We show the preliminary results of this experimental campaign, and especially the ones showing the production of multicharged ions having very narrow energy spreads.
Focused ion beam source method and apparatus
Pellin, Michael J.; Lykke, Keith R.; Lill, Thorsten B.
2000-01-01
A focused ion beam having a cross section of submicron diameter, a high ion current, and a narrow energy range is generated from a target comprised of particle source material by laser ablation. The method involves directing a laser beam having a cross section of critical diameter onto the target, producing a cloud of laser ablated particles having unique characteristics, and extracting and focusing a charged particle beam from the laser ablated cloud. The method is especially suited for producing focused ion beams for semiconductor device analysis and modification.
Low-Energy Sputtering Studies of Boron Nitride with Xenon Ions
NASA Technical Reports Server (NTRS)
Ray, P. K.; Shutthanandan, V.
1999-01-01
Sputtering of boron nitride with xenon ions was investigated using secondary ion (SIMS) and secondary neutral (SNMS) mass spectrometry. The ions generated from the ion gun were incident on the target at an angle of 50' with respect to the surface'normal. The energy of ions ranged from 100 eV to 3 keV. A flood electron gun was used to neutralize the positive charge build-up on the target surface. The intensities of sputtered neutral and charged particles, including single atoms, molecules, and clusters, were measured as a function of ion energy. Positive SIMS spectra were dominated by the two boron isotopes whereas BN- and B- were the two major constituents of the negative SIMS spectra. Nitrogen could be detected only in the SNMS spectra. The intensity-energy curves of the sputtered particles were similar in shape. The knees in P-SIMS and SNMS intensity-energy curves appear at around I keV which is significantly higher that 100 to 200 eV energy range at which knees appear in the sputtering of medium and heavy elements by ions of argon and xenon. This difference in the position of the sputter yield knee between boron nitride and heavier targets is due to the reduced ion energy differences. The isotopic composition of secondary ions of boron were measured by bombarding boron nitride with xenon ions at energies ranging from 100 eV to 1.5 keV using a quadrupole mass spectrometer. An ion gun was used to generate the ion beam. A flood electron gun was used to neutralize the positive charge buildup on the target surface. The secondary ion flux was found to be enriched in heavy isotopes at lower incident ion energies. The heavy isotope enrichment was observed to decrease with increasing primary ion energy. Beyond 350 eV, light isotopes were sputtered preferentially with the enrichment increasing to an asymptotic value of 1.27 at 1.5 keV. The trend is similar to that of the isotopic enrichment observed earlier when copper was sputtered with xenon ions in the same energy
Secondary batteries with multivalent ions for energy storage
Xu, Chengjun; Chen, Yanyi; Shi, Shan; Li, Jia; Kang, Feiyu; Su, Dangsheng
2015-01-01
The use of electricity generated from clean and renewable sources, such as water, wind, or sunlight, requires efficiently distributed electrical energy storage by high-power and high-energy secondary batteries using abundant, low-cost materials in sustainable processes. American Science Policy Reports state that the next-generation “beyond-lithium” battery chemistry is one feasible solution for such goals. Here we discover new “multivalent ion” battery chemistry beyond lithium battery chemistry. Through theoretic calculation and experiment confirmation, stable thermodynamics and fast kinetics are presented during the storage of multivalent ions (Ni2+, Zn2+, Mg2+, Ca2+, Ba2+, or La3+ ions) in alpha type manganese dioxide. Apart from zinc ion battery, we further use multivalent Ni2+ ion to invent another rechargeable battery, named as nickel ion battery for the first time. The nickel ion battery generally uses an alpha type manganese dioxide cathode, an electrolyte containing Ni2+ ions, and Ni anode. The nickel ion battery delivers a high energy density (340 Wh kg−1, close to lithium ion batteries), fast charge ability (1 minute), and long cycle life (over 2200 times). PMID:26365600
NASA Astrophysics Data System (ADS)
Yoshimura, Satoru; Sugimoto, Satoshi; Takeuchi, Takae; Murai, Kensuke; Kiuchi, Masato
2018-04-01
We mass-selected SiC3H9+ ions from various fragments produced through the decomposition of hexamethyldisilane, and finally produced low-energy SiC3H9+ ion beams. The ion beams were injected into Si(1 0 0) substrates and the dependence of deposited films on injected ion energy was then investigated. Injected ion energies were 20, 100, or 200 eV. Films obtained were investigated with X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. X-ray diffraction and X-ray photoelectron spectroscopy of the substrates obtained following the injection of 20 eV ions demonstrated the occurrence of silicon carbide film (3C-SiC) deposition. On the other hand, Raman spectroscopy showed that the films deposited by the injection of 100 or 200 eV ions included 3C-SiC plus diamond-like carbon. Ion beam deposition using hexamethyldisilane-derived 20 eV SiC3H9+ ions is an efficient technique for 3C-SiC film formation on Si substrates.
1992-05-28
ORGANIZATION (if applicable) Office of Naval Research N00014-87- j - 1248 Bc. ADDRESS (City, State, and ZIP Code) 10. SOURCE OF FUNDING NUMBERS 800 N. Quincy St...RESEARCH Grant NOOO14-87- J -1248 R & T Code 4134052 TECHNICAL REPORT NO. 36 Probing Trapped Ion Energies Via Ion-Molecule Reaction Kinetics: Fourier...reactivity (for charge transfer with N2) of the higher energy J =1/2 state is approximately three times that of the J =3/2 state at collision energies
Axial energy spread measurements of an accelerated positive ion beam
NASA Astrophysics Data System (ADS)
Lee, Y.; Gough, R. A.; Kunkel, W. B.; Leung, K. N.; Perkins, L. T.; Pickard, D. S.; Sun, L.; Vujic, J.; Williams, M. D.; Wutte, D.; Mondelli, Alfred A.; Stengl, Gerhard
1997-01-01
A multicusp ion source has been designed for use in ion projection lithography. Longitudinal energy spreads of the extracted positive hydrogen ion beam have been studied using a retarding field energy analyzer. It has been found that the filament-discharge multicusp ion source can deliver a beam with an energy spread less than 3 eV which is required for the ALG-1000 machine. The multicusp ion source can also deliver the current required for the application.
Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions
NASA Astrophysics Data System (ADS)
Alejo, A.; Green, A.; Ahmed, H.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; McKenna, P.; Mirfayzi, S. R.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.; Kar, S.
2016-09-01
The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.
Dynamics of nanoparticle morphology under low energy ion irradiation.
Holland-Moritz, Henry; Graupner, Julia; Möller, Wolfhard; Pacholski, Claudia; Ronning, Carsten
2018-08-03
If nanostructures are irradiated with energetic ions, the mechanism of sputtering becomes important when the ion range matches about the size of the nanoparticle. Gold nanoparticles with diameters of ∼50 nm on top of silicon substrates with a native oxide layer were irradiated by gallium ions with energies ranging from 1 to 30 keV in a focused ion beam system. High resolution in situ scanning electron microscopy imaging permits detailed insights in the dynamics of the morphology change and sputter yield. Compared to bulk-like structures or thin films, a pronounced shaping and enhanced sputtering in the nanostructures occurs, which enables a specific shaping of these structures using ion beams. This effect depends on the ratio of nanoparticle size and ion energy. In the investigated energy regime, the sputter yield increases at increasing ion energy and shows a distinct dependence on the nanoparticle size. The experimental findings are directly compared to Monte Carlo simulations obtained from iradina and TRI3DYN, where the latter takes into account dynamic morphological and compositional changes of the target.
Relationship between wave energy and free energy from pickup ions in the Comet Halley environment
NASA Technical Reports Server (NTRS)
Huddleston, D. E.; Johnstone, A. D.
1992-01-01
The free energy available from the implanted heavy ion population at Comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. Upstream and downstream free energies are obtained separately for the conditions observed along the Giotto spacecraft trajectory. The results indicate that the waves are mostly upstream propagating in the solar wind frame. The total free energy density always exceeds the measured wave energy density because, as expected in the nonlinear process of ion scattering, the available energy is not all immediately released. An estimate of the amount which has been released can be obtained from the measured oxygen ion distributions and again it exceeds that observed. The theoretical analysis is extended to calculate the k spectrum of the cometary-ion-generated turbulence.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mathew, Jose V.; Paul, Samit; Bhattacharjee, Sudeep
2010-05-15
An earlier study of the axial ion energy distribution in the extraction region (plasma meniscus) of a compact microwave plasma ion source showed that the axial ion energy spread near the meniscus is small ({approx}5 eV) and comparable to that of a liquid metal ion source, making it a promising candidate for focused ion beam (FIB) applications [J. V. Mathew and S. Bhattacharjee, J. Appl. Phys. 105, 96101 (2009)]. In the present work we have investigated the radial ion energy distribution (IED) under the influence of beam extraction. Initially a single Einzel lens system has been used for beam extractionmore » with potentials up to -6 kV for obtaining parallel beams. In situ measurements of IED with extraction voltages upto -5 kV indicates that beam extraction has a weak influence on the energy spread ({+-}0.5 eV) which is of significance from the point of view of FIB applications. It is found that by reducing the geometrical acceptance angle at the ion energy analyzer probe, close to unidirectional distribution can be obtained with a spread that is smaller by at least 1 eV.« less
Enhancements to the Low-Energy Ion Facility at SUNY Geneseo
NASA Astrophysics Data System (ADS)
Barfield, Zachariah; Kostick, Steven; Nagasing, Ethan; Fletcher, Kurt; Padalino, Stephen
2017-10-01
The Low Energy Ion Facility at SUNY Geneseo is used for detector development and characterization for inertial confinement fusion diagnostics. The system has been upgraded to improve the ion beam quality by reducing contaminant ions. In the new configuration, ions produced by the Peabody Scientific duoplasmatron ion source are accelerated through a potential, focused into a new NEC analyzing magnet and directed to an angle of 30°. A new einzel lens on the output of the magnet chamber focuses the beam into a scattering chamber with a water-cooled target mount and rotatable detector mount plates. The analyzing magnet has been calibrated for deuteron, 4He+, and 4He2+ ion beams at a range of energies, and no significant hysteresis has been observed. The system can accelerate deuterons to energies up to 25 keV to initiate d-d fusion using a deuterated polymer target. Charged particle spectra with protons, tritons, and 3He ions from d-d fusion have been measured at scattering angles ranging from 55° to 135°. A time-of-flight beamline has been designed to measure the energies of ions elastically scattered at 135°. CEM detectors initiate start and stop signals from secondary electrons produced when low energy ions pass through very thin carbon foils. Funded in part by the U.S. Department of Energy through the Laboratory for Laser Energetics.
Energy transfer from Pr3+ to Gd3+ ions in BaB8O13 phosphor for phototherapy lamps
NASA Astrophysics Data System (ADS)
Tamboli, Sumedha; Nair, Govind B.; Dhoble, S. J.; Burghate, D. K.
2018-04-01
A series of BaB8O13 phosphors doped with different concentrations of Gd3+ ions and co-doped with Pr3+ ions were synthesized by solid state synthesis method. X-ray powder diffraction (XRD) analysis confirmed the formation of the compound in a crystalline and homogeneous form. Scanning Electron Microscopy (SEM) was performed to study the surface morphology of the compound and Fourier Transform Infrared (FT-IR) spectroscopy measurements determined the nature of bonding between elements of the compounds. The photoluminescence (PL) excitation spectra of BaB8O13:Gd3+ phosphor showed excitation peaks at 246 nm, 252 nm and 274 nm. The prominent emission peak was observed at 313 nm which is in narrow band ultraviolet B (NB-UVB) range. Energy transfer was achieved by co-doping Pr3+ ions with Gd3+ ions. PL decay time was also measured for BaB8O13: Gd3+, Pr3+ phosphor. Emission at 313 nm can be used for the treatment of skin diseases.
Low energy spread ion source with a coaxial magnetic filter
Leung, Ka-Ngo; Lee, Yung-Hee Yvette
2000-01-01
Multicusp ion sources are capable of producing ions with low axial energy spread which are necessary in applications such as ion projection lithography (IPL) and radioactive ion beam production. The addition of a radially extending magnetic filter consisting of a pair of permanent magnets to the multicusp source reduces the energy spread considerably due to the improvement in the uniformity of the axial plasma potential distribution in the discharge region. A coaxial multicusp ion source designed to further reduce the energy spread utilizes a cylindrical magnetic filter to achieve a more uniform axial plasma potential distribution. The coaxial magnetic filter divides the source chamber into an outer annular discharge region in which the plasma is produced and a coaxial inner ion extraction region into which the ions radially diffuse but from which ionizing electrons are excluded. The energy spread in the coaxial source has been measured to be 0.6 eV. Unlike other ion sources, the coaxial source has the capability of adjusting the radial plasma potential distribution and therefore the transverse ion temperature (or beam emittance).
Low energy implantation of boron with decaborane ions
NASA Astrophysics Data System (ADS)
Albano, Maria Angela
The goal of this dissertation was to determine the feasibility of a novel approach to forming ultra shallow p-type junctions (tens of nm) needed for future generations of Si MOS devices. In the new approach, B dopant atoms are implanted by cluster ions obtained by ionization of decaborane (B 10H14) vapor. An experimental ion implanter with an electron impact ion source and magnetic mass separation was built at the Ion Beam and Thin Film Research Laboratory at NJIT. Beams of B10Hx+ ions with currents of a few microamperes and energies of 1 to 12 keV were obtained and used for implantation experiments. Profiles of B and H atoms implanted in Si were measured by Secondary Ion Mass Spectroscopy (SIMS) before and after rapid thermal annealing (RTA). From the profiles, the junction depth of 57 nm (at 1018 cm-3 B concentration) was obtained with 12 keV decaborane ions followed by RTA. The dose of B atoms that can be implanted at low energy into Si is limited by sputtering as the ion beam sputters both the matrix and the implanted atoms. As the number of sputtered B atoms increases with the implanted dose and approaches the number of the implanted atoms, equilibrium of B in Si is established. This effect was investigated by comparison of the B dose calculated from the ion beam integration with B content in the sample measured by Nuclear Reaction Analysis (NRA). Maximum (equilibrium) doses of 1.35 x 1016 B cm -2 and 2.67 x 1016 B cm-2 were obtained at the beam energies of 5 and 12 keV, respectively. The problem of forming shallow p-type junctions in Si is related not only to implantation depth, but also to transient enhanced diffusion (TED). TED in Si implanted with B10Hx+ was measured on boron doping superlattice (B-DSL) marker layers. It was found that TED, following decaborane implantation, is the same as with monomer B+ ion implantation of equivalent energy and that it decreases with the decreasing ion energy. (Abstract shortened by UMI.)
Plasma expansion dynamics physics: An understanding on ion energy reduction process
NASA Astrophysics Data System (ADS)
Ruzic, David; Srivastava, Shailendra; Thompson, Keith; Spencer, Joshua; Sporre, John
2007-11-01
This paper studies the expanding plasma dynamics of ions produced from a 5J Z-pinch xenon light source used for EUV lithography. Ion energy reduction is essential for the successful implementation of this technology. To aid this investigation, ion energy from a z-pinch DPP plasma source is measured using an ion energy analyzer and effect of introducing a small percentage of low Z material on the ion energy and flux is investigated. Presence of low mass such as H2 or N2, shows a considerable reduction in total flux and in average energy. For example, Xe^+ ion flux at 5 keV are recorded as 425 ± 42 ions/cm^2.eV.pulse at 157 cm and reduced to 125 ± 12 ions/cm^2.eV.pulse when using the low mass into the system at same energy. It is also noticed that such a combination leads to decrease in sputtering without changing the EUV output. Study of the possible mechanism supporting the experimental results is numerically calculated. This computational work indicates that the observed high energies of ions are probably resulting from coulomb explosion initiated by pinch instability. It is postulated that the electrons leave first setting up an electrostatic potential which accelerates the ions. The addition of small mass actually screens the potential and decorates the ions.
Free Energy Wells and Barriers to Ion Transport Across Membranes
NASA Astrophysics Data System (ADS)
Rempe, Susan
2014-03-01
The flow of ions across cellular membranes is essential to many biological processes. Ion transport is also important in synthetic materials used as battery electrolytes. Transport often involves specific ions and fast conduction. To achieve those properties, ion conduction pathways must solvate specific ions by just the ``right amount.'' The right amount of solvation avoids ion traps due to deep free energy wells, and avoids ion block due to high free energy barriers. Ion channel proteins in cellular membranes demonstrate this subtle balance in solvation of specific ions. Using ab initio molecular simulations, we have interrogated the link between binding site structure and ion solvation free energies in biological ion binding sites. Our results emphasize the surprisingly important role of the environment that surrounds ion-binding sites for fast transport of specific ions. We acknowledge support from Sandia's LDRD program. Sandia National Labs is a multi-program laboratory operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the US DOE's NNSA under contract DE-AC04-94AL85000.
Energy spectrum of argon ions emitted from Filippov type Sahand plasma focus.
Mohammadnejad, M; Pestehe, S J; Mohammadi, M A
2013-07-01
The energy and flux of the argon ions produced in Sahand plasma focus have been measured by employing a well-designed Faraday cup. The secondary electron emission effects on the ion signals are simulated and the dimensions of Faraday cup are optimized to minimize these effects. The measured ion energy spectrum is corrected for the ion energy loss and charge exchange in the background gas. The effects of the capacitor bank voltage and working gas pressure on the ion energy spectrum are also investigated. It has been shown that the emitted ion number per energy increases as the capacitor bank voltage increases. Decreasing the working gas pressure leads to the increase in the number of emitted ion per energy.
Electron energy recovery system for negative ion sources
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.
Analysis of the theory of high energy ion transport
NASA Technical Reports Server (NTRS)
Wilson, J. W.
1977-01-01
Procedures for the approximation of the transport of high-energy ions are discussed on the basis of available data on ion nuclear reactions. A straightahead approximation appears appropriate for space applications. The assumption that the secondary-ion-fragment velocity is equal to that of the fragmenting nucleus is inferior to straightahead theory but is of sufficient accuracy if the primary ions display a broad energy spectrum. An iterative scheme for the solution of the inhomogenous integral transport equations holds promise for practical calculation. A model calculation shows that multiple charged ion fragments penetrate to greater depths in comparison with the free path of a primary heavy ion.
The shape of ion tracks in natural apatite
NASA Astrophysics Data System (ADS)
Schauries, D.; Afra, B.; Bierschenk, T.; Lang, M.; Rodriguez, M. D.; Trautmann, C.; Li, W.; Ewing, R. C.; Kluth, P.
2014-05-01
Small angle X-ray scattering measurements were performed on natural apatite of different thickness irradiated with 2.2 GeV Au swift heavy ions. The evolution of the track radius along the full ion track length was estimated by considering the electronic energy loss and the velocity of the ions. The shape of the track is nearly cylindrical, slightly widening with a maximum diameter approximately 30 μm before the ions come to rest, followed by a rapid narrowing towards the end within a cigar-like contour. Measurements of average ion track radii in samples of different thicknesses, i.e. containing different sections of the tracks are in good agreement with the shape estimate.
A Penning sputter ion source with very low energy spread
NASA Astrophysics Data System (ADS)
Nouri, Z.; Li, R.; Holt, R. A.; Rosner, S. D.
2010-03-01
We have developed a version of the Frankfurt Penning ion source that produces ion beams with very low energy spreads of ˜3 eV, while operating in a new discharge mode characterized by very high pressure, low voltage, and high current. The extracted ions also comprise substantial metastable and doubly charged species. Detailed studies of the operating parameters of the source showed that careful adjustment of the magnetic field and gas pressure is critical to achieving optimum performance. We used a laser-fluorescence method of energy analysis to characterize the properties of the extracted ion beam with a resolving power of 1×10 4, and to measure the absolute ion beam energy to an accuracy of 4 eV in order to provide some insight into the distribution of plasma potential within the ion source. This characterization method is widely applicable to accelerator beams, though not universal. The low energy spread, coupled with the ability to produce intense ion beams from almost any gas or conducting solid, make this source very useful for high-resolution spectroscopic measurements on fast-ion beams.
Energy transport in weakly nonlinear wave systems with narrow frequency band excitation.
Kartashova, Elena
2012-10-01
A novel discrete model (D model) is presented describing nonlinear wave interactions in systems with small and moderate nonlinearity under narrow frequency band excitation. It integrates in a single theoretical frame two mechanisms of energy transport between modes, namely, intermittency and energy cascade, and gives the conditions under which each regime will take place. Conditions for the formation of a cascade, cascade direction, conditions for cascade termination, etc., are given and depend strongly on the choice of excitation parameters. The energy spectra of a cascade may be computed, yielding discrete and continuous energy spectra. The model does not require statistical assumptions, as all effects are derived from the interaction of distinct modes. In the example given-surface water waves with dispersion function ω(2)=gk and small nonlinearity-the D model predicts asymmetrical growth of side-bands for Benjamin-Feir instability, while the transition from discrete to continuous energy spectrum, excitation parameters properly chosen, yields the saturated Phillips' power spectrum ~g(2)ω(-5). The D model can be applied to the experimental and theoretical study of numerous wave systems appearing in hydrodynamics, nonlinear optics, electrodynamics, plasma, convection theory, etc.
Broad ion energy distributions in helicon wave-coupled helium plasma
NASA Astrophysics Data System (ADS)
Woller, K. B.; Whyte, D. G.; Wright, G. M.
2017-05-01
Helium ion energy distributions were measured in helicon wave-coupled plasmas of the dynamics of ion implantation and sputtering of surface experiment using a retarding field energy analyzer. The shape of the energy distribution is a double-peak, characteristic of radiofrequency plasma potential modulation. The broad distribution is located within a radius of 0.8 cm, while the quartz tube of the plasma source has an inner radius of 2.2 cm. The ion energy distribution rapidly changes from a double-peak to a single peak in the radius range of 0.7-0.9 cm. The average ion energy is approximately uniform across the plasma column including the double-peak and single peak regions. The widths of the broad distribution, ΔE , in the wave-coupled mode are large compared to the time-averaged ion energy, ⟨E ⟩. On the axis (r = 0), ΔE / ⟨E ⟩ ≲ 3.4, and at a radius near the edge of the plasma column (r = 2.2 cm), ΔE / ⟨E ⟩ ˜ 1.2. The discharge parameter space is scanned to investigate the effects of the magnetic field, input power, and chamber fill pressure on the wave-coupled mode that exhibits the sharp radial variation in the ion energy distribution.
Analysis of retarding field energy analyzer transmission by simulation of ion trajectories
NASA Astrophysics Data System (ADS)
van de Ven, T. H. M.; de Meijere, C. A.; van der Horst, R. M.; van Kampen, M.; Banine, V. Y.; Beckers, J.
2018-04-01
Retarding field energy analyzers (RFEAs) are used routinely for the measurement of ion energy distribution functions. By contrast, their ability to measure ion flux densities has been considered unreliable because of lack of knowledge about the effective transmission of the RFEA grids. In this work, we simulate the ion trajectories through a three-gridded RFEA using the simulation software SIMION. Using idealized test cases, it is shown that at high ion energy (i.e., >100 eV) the transmission is equal to the optical transmission rather than the product of the individual grid transparencies. Below 20 eV, ion trajectories are strongly influenced by the electric fields in between the grids. In this region, grid alignment and ion focusing effects contribute to fluctuations in transmission with ion energy. Subsequently the model has been used to simulate the transmission and energy resolution of an experimental RFEA probe. Grid misalignments reduce the transmission fluctuations at low energy. The model predicts the minimum energy resolution, which has been confirmed experimentally by irradiating the probe with a beam of ions with a small energy bandwidth.
The dynamics of energy and charge transfer in low and hyperthermal energy ion-solid interactions
NASA Astrophysics Data System (ADS)
Ray, Matthew Preston
The energy and charge transfer dynamics for low and hyperthermal energy (10 eV to 2 keV) alkali and noble gas ions impacting noble metals as a function of incident energy, species and scattering geometry has been studied. The experiments were performed in an ultra-high vacuum scattering chamber attached to a low and hyperthermal energy beamline. The energy transfer was measured for K+ scattered from a Ag(001) surface along the [110] crystalline direction at a fixed laboratory angle of 90°. It was found that as the incident energy is reduced from 100 to 10 eV, the normalized scattered energy increased. Previous measurements have shown a decrease in the normalized energy as the incident ion energy is reduced due to an attractive image force. Trajectory analysis of the data using a classical scattering simulation revealed that instead of undergoing sequential binary collisions as in previous studies, the ion scatters from two surface atoms simultaneously leading to an increased normalized energy. Additionally, charge transfer measurements have been performed for Na + scattering from Ag(001) along the [110] crystalline direction at a fixed laboratory angle of 70°. It was found that over the range of energies used (10 eV to 2 keV), the neutralization probability of the scattered ions varied from ˜30% to ˜70% depending on the incident velocity, consistent with resonant charge transfer. A fully quantum mechanical model that treats electrons independently accurately reproduces the observed data. Measurements of electron-hole pair excitations were used to explore the pathways which a solid uses to dissipate the energy imparted by the incident ion beam. Ultrathin film (10 nm) metal-oxide-semiconductor (Au/SiO2/n-Si) devices were used to detect the electron-hole pairs for cases when the ion deposited all of its translational energy into the solid. The incident ions were incident at an angle normal to the surface of the device to maximize energy deposition and consequently
Spectral modification of shock accelerated ions using a hydrodynamically shaped gas target
Tresca, O.; Polyanskiy, M. N.; Dover, N. P.; ...
2015-08-28
We report on reproducible shock acceleration from irradiation of a λ=10 μm CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I≲10 14 W cm –2) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>10 16 W cm –2) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μm), broadband beams of He + and H + were routinely produced,more » whilst for shorter gradients (≲20 μm), quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Malapit, Giovanni M.; Department of Physical Sciences, University of the Philippines Baguio, Baguio City 2600; Mahinay, Christian Lorenz S.
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 themore » 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.« less
Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination
NASA Astrophysics Data System (ADS)
Krükow, Artjom; Mohammadi, Amir; Härter, Arne; Denschlag, Johannes Hecker; Pérez-Ríos, Jesús; Greene, Chris H.
2016-05-01
We study three-body recombination of Ba++Rb +Rb in the mK regime where a single 138Ba+ ion in a Paul trap is immersed into a cloud of ultracold 87Rb atoms. We measure the energy dependence of the three-body rate coefficient k3 and compare the results to the theoretical prediction, k3∝Ecol-3 /4, where Ecol is the collision energy. We find agreement if we assume that the nonthermal ion energy distribution is determined by at least two different micromotion induced energy scales. Furthermore, using classical trajectory calculations we predict how the median binding energy of the formed molecules scales with the collision energy. Our studies give new insights into the kinetics of an ion immersed in an ultracold atom cloud and yield important prospects for atom-ion experiments targeting the s -wave regime.
Low energy sputtering of cobalt by cesium ions
NASA Technical Reports Server (NTRS)
Handoo, A.; Ray, Pradosh K.
1989-01-01
An experimental facility to investigate low energy (less than 500 eV) sputtering of metal surfaces with ions produced by an ion gun is described. Results are reported on the sputtering yield of cobalt by cesium ions in the 100 to 500 eV energy range at a pressure of 1 times 10(exp -6) Torr. The target was electroplated on a copper substrate. The sputtered atoms were collected on a cobalt foil surrounding the target. Co-57 was used as a tracer to determine the sputtering yield.
Importance of ion energy on SEU in CMOS SRAMs
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dodd, P.E.; Shaneyfelt, M.R.; Sexton, F.W.
1998-03-01
The single-event upset (SEU) responses of 16 Kbit to 1 Mbit SRAMs irradiated with low and high-energy heavy ions are reported. Standard low-energy heavy ion tests appear to be sufficiently conservative for technologies down to 0.5 {micro}m.
Observations of low-energy ions with Arase/LEPi
NASA Astrophysics Data System (ADS)
Yoshizumi, M.; Asamura, K.; Kazama, Y.; Yokota, S.; Kasahara, S.
2017-12-01
LEPi is one of the instruments onboard Arase, which is an energy-mass spectrometer designed to measure ions with energies from 0.01keV/q up to 25keV/q. In order to discriminate species of incoming ions, LEPi uses a TOF (Time-Of-Flight) technique. TOF also works as a noise rejector, which is useful for rejection of background noise due to high energy particles in the inner magnetosphere. LEPi has passed the initial checkout phase after launch, and now under regular observations. Since the regular observation started (end of March, 2017), Arase encountered several magnetic storms driven by CIR and CMEs. LEPi observed sudden flux enhancement and subsequent gradual decay of low-energy ( 10eV/q) ions around L=4 associated with the magnetic storms. In some cases, these flux modulations coinside with eclipse (absent of Sun light on the spacecraft), but others do not. Spacecraft potential decreases when the spacecraft gets eclipse. Therefore, a part of ions whose enegies are lower than energy range of LEPi are accelerated and appeared in the range. These fluxes might reflect transportation / energization of cold component in the inner magnetosphere. We will present current LEPi operations and initial scientific results.
Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel
DOE Office of Scientific and Technical Information (OSTI.GOV)
Fritsch, Sebastian; Ivanov, Ivaylo; Wang, Hailong
2010-01-01
The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high-resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential-of-mean-force profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel ismore » open for a sodium ion to transport, but presents a 11 kcal/mol free energy barrier for a chloride ion. Our collective findings identify three distinct contributions to the observed preference for the permeant ions. First, there is a substantial contribution due to a ring of negatively charged glutamate residues (E-2 ) at the narrow intracellular end of the channel. The negative electrostatics of this region and the ability of the glutamate side chains to directly bind cations would strongly favor the passage of sodium ions while hindering translocation of chloride ions. Second, our results imply a significant hydrophobic contribution to selectivity linked to differences in the desolvation penalty for the sodium versus chloride ions in the central hydrophobic region of the pore. This hydrophobic contribution is evidenced by the large free energy barriers experienced by Cl in the middle of the pore for both GLIC and the E-2 A mutant. Finally, there is a distinct contribution arising from the overall negative electrostatics of the channel.« less
Coulomb-driven energy boost of heavy ions for laser-plasma acceleration.
Braenzel, J; Andreev, A A; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnürer, M
2015-03-27
An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultrathin gold foils have been irradiated by an ultrashort laser pulse at a peak intensity of 8×10^{19} W/ cm^{2}. Highly charged gold ions with kinetic energies up to >200 MeV and a bandwidth limited energy distribution have been reached by using 1.3 J laser energy on target. 1D and 2D particle in cell simulations show how a spatial dependence on the ion's ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target, leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser-driven heavy ion acceleration.
Applications of high-energy heavy-ions from superconducting cyclotrons
DOE Office of Scientific and Technical Information (OSTI.GOV)
Grimm, T. L.
1999-06-10
The superconducting cyclotrons of the National Superconducting Cyclotron Laboratory (NSCL), a major nuclear physics facility, can provide ions of any element from hydrogen to uranium. A major upgrade to the NSCL is underway and will consist of an electron cyclotron resonance (ECR) ion source followed by two large superconducting cyclotrons (K500 and K1200). Ions can be extracted at any point along this chain allowing a large range of energies and charge states. The ion energies range from a few keV to over 20 GeV, and charge states up to fully stripped {sup 197}Au{sup 79+} and two electron {sup 238}U{sup 90+}more » are possible. The long range of the high-energy heavy-ions allows them to penetrate deeply into a target that is placed in air, outside a vacuum chamber. The ion beams have already been used for a number of applications including; ion implantation, atomic physics, single event effects in integrated circuits, DNA radiation studies, radiation detector studies, flux pinning in high-T{sub c} superconductors, calibration of a space-based spectrometer, isotropic ratio measurements, material wear studies, and continuous positron emission tomography imaging.« less
Two-dimensional silicon-based detectors for ion beam therapy
NASA Astrophysics Data System (ADS)
Martišíková, M.; Granja, C.; Jakůbek, J.; Hartmann, B.; Telsemeyer, J.; Huber, L.; Brons, S.; Pospíšil, S.; Jäkel, O.
2012-02-01
Radiation therapy with ion beams is a highly precise kind of cancer treatment. As ion beams traverse material, the highest ionization density occurs at the end of their path. Due to this Bragg-peak, ion beams enable higher dose conformation to the tumor and increased sparing of the surrounding tissue, in comparison to standard radiation therapy using high energy photons. Ions heavier than protons offer in addition increased biological effectiveness and lower scattering. The Heidelberg Ion Beam Therapy Center (HIT) is a state-of-the-art ion beam therapy facility and the first hospital-based facility in Europe. It provides proton and carbon ion treatments. A synchrotron is used for ion acceleration. For dose delivery to the patient, narrow pencil-like beams are scanned over the target volume.
Energy distribution functions of kilovolt ions in a modified Penning discharge.
NASA Technical Reports Server (NTRS)
Roth, J. R.
1973-01-01
The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge-exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space, and result in an isotropic energy distribution.
Energy distribution functions of kilovolt ions in a modified Penning discharge.
NASA Technical Reports Server (NTRS)
Roth, J. R.
1972-01-01
The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge-exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space, and result in an isotropic energy distribution.
NASA Astrophysics Data System (ADS)
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, H. F.; Cheng, J.; Cherney, M.; Christie, W.; Codrington, M. J. M.; Contin, G.; Crawford, H. J.; Cui, X.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Filip, P.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, X.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, Z. M.; Li, X.; Li, W.; Li, Y.; Li, X.; Li, C.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, R. M.; Ma, Y. G.; Magdy, N.; Mahapatra, D. P.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Simko, M.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solanki, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X. M.; Sun, Z.; Sun, Y.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Takahashi, J.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, H.; Wang, F.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, N.; Xu, Z.; Xu, H.; Xu, Y.; Xu, Q. H.; Yan, W.; Yang, Y.; Yang, C.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Z. P.; Zhang, J. B.; Zhang, J. L.; Zhang, Y.; Zhang, S.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, Y. H.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration
2016-08-01
Balance functions have been measured in terms of relative pseudorapidity (Δ η ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at √{sNN}=7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at √{sNN}=2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at √{sNN}=7.7 GeV implies that a QGP is still being created at this relatively low energy.
Energy and Pitch Distribution of Spontaneously-generated High-energy Bulk Ions in the RFP
NASA Astrophysics Data System (ADS)
Kim, Jungha; Anderson, Jay; Reusch, Joshua; Eilerman, Scott; Capecchi, William
2014-10-01
Magnetic reconnection events in the reversed field pinch (RFP) are known to heat bulk and impurity ions. Runaway due to a parallel electric field has recently been confirmed as an important acceleration mechanism for high energy test ions supplied by a neutral beam. This effect does not, however, explain the change in distribution of nearly Maxwellian bulk ions at a reconnection event. By operating MST near maximum current and low electron density, significant fusion neutron flux can be generated without neutral beam injection. The bulk ion distribution created in these plasmas is well-confined, non-Maxwellian, and can be measured by the Advanced Neutral Particle Analyzer (ANPA) placed at a radial or tangential porthole. Data show a high energy tail up to 25 keV with a relatively higher signal in the low energy channels (8-15 keV) at the radial port following a reconnection event. Analysis of the energy dependence of trapped orbits sampled by the ANPA at the radial view implies an abundance of lower energy particles in regions of higher neutral density. This mandates a careful deconvolution of the measured ANPA signal to compute the fast ion distribution. This work is supported by the US DOE and NSF.
High peak current acceleration of narrow divergence ions beams with the BELLA-PW laser
NASA Astrophysics Data System (ADS)
Steinke, Sven; Ji, Qing; Treffert, Franziska; Bulanov, Stepan; Bin, Jianhui; Nakamura, Kei; Gonsalves, Anthony; Toth, Csaba; Park, Jaehong; Roth, Markus; Esarey, Eric; Schenkel, Thomas; Leemans, Wim
2017-10-01
We present a parameter study of ion acceleration driven by the BELLA-PW laser. The laser repetition rate of 1Hz allowed for scanning the laser pulse duration, relative focus location and target thickness for the first time at laser peak powers of above 1 petawatt. Further, the long focal length geometry of the experiment (f\\65) and hence, large focus size provided ion beams of reduced divergence and unprecedented charge density. This work was supported by Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and Laboratory Directed Research and Development (LDRD) funding from Lawrence Berkeley National Laboratory.
Energy distribution functions of kilovolt ions in a modified Penning discharge
NASA Technical Reports Server (NTRS)
Roth, J. R.
1972-01-01
The distribution function of ion energy parallel to the magnetic field of a Penning discharge was measured with a retarding potential energy analyzer. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field were made with a charge-exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and their kinetic temperatures are equal within experimental error. This suggests that turbulent processes previously observed Maxwellianize the velocity distribution along a radius in velocity space, and result in an isotropic energy distribution. The kinetic temperatures are on the order of kilovolts, and the tails of the ion energy distribution functions are Maxwellian up to a factor of 7 e-folds in energy. When the distributions depart from Maxwellian, they are enhanced above the Maxwellian tail. Above densities of about 10 to the 10th power particles/cc, this enhancement appears to be the result of a second, higher temperature Maxwellian distribution. At these high particle energies, only the ions perpendicular to the magnetic field lines were investigated.
Ion energy spread and current measurements of the rf-driven multicusp ion source
NASA Astrophysics Data System (ADS)
Lee, Y.; Gough, R. A.; Kunkel, W. B.; Leung, K. N.; Perkins, L. T.; Pickard, D. S.; Sun, L.; Vujic, J.; Williams, M. D.; Wutte, D.
1997-03-01
Axial energy spread and useful beam current of positive ion beams have been carried out using a radio frequency (rf)-driven multicusp ion source. Operating the source with a 13.56 MHz induction discharge, the axial energy spread is found to be approximately 3.2 eV. The extractable beam current of the rf-driven source is found to be comparable to that of filament-discharge sources. With a 0.6 mm diameter extraction aperture, a positive hydrogen ion beam current density of 80 mA/cm2 can be obtained at a rf input power of 2.5 kW. The expected source lifetime is much longer than that of filament discharges.
Computer-Controlled System for Plasma Ion Energy Auto-Analyzer
NASA Astrophysics Data System (ADS)
Wu, Xian-qiu; Chen, Jun-fang; Jiang, Zhen-mei; Zhong, Qing-hua; Xiong, Yu-ying; Wu, Kai-hua
2003-02-01
A computer-controlled system for plasma ion energy auto-analyzer was technically studied for rapid and online measurement of plasma ion energy distribution. The system intelligently controls all the equipments via a RS-232 port, a printer port and a home-built circuit. The software designed by Lab VIEW G language automatically fulfils all of the tasks such as system initializing, adjustment of scanning-voltage, measurement of weak-current, data processing, graphic export, etc. By using the system, a few minutes are taken to acquire the whole ion energy distribution, which rapidly provides important parameters of plasma process techniques based on semiconductor devices and microelectronics.
Ion-Acoustic Wave-Particle Energy Flow Rates
NASA Astrophysics Data System (ADS)
Berumen, Jorge; Chu, Feng; Hood, Ryan; Mattingly, Sean; Skiff, Fred
2017-10-01
We present an experimental characterization of the energy flow rates for ion acoustic waves. The experiment is performed in a cylindrical, magnetized, singly-ionized Argon, inductively-coupled gas discharge plasma that is weakly collisional with typical conditions: n 109cm-3 Te 9 eV and B 660 kG. A 4 ring antenna with diameter similar to the plasma diameter is used for launching the waves. A survey of the zeroth and first order ion velocity distribution functions (IVDF) is done using Laser-Induced Fluorescence (LIF) as the main diagnostics method. Using these IVDFs along with Vlasov's equation the different energy rates are measured for different values of ion velocity and separation from the antenna. We would like to acknowledge DOE DE-FG02-99ER54543 for their financial support throughout this research.
NASA Astrophysics Data System (ADS)
Hilgers, G.; Bug, M. U.; Rabus, H.
2017-10-01
Ionization cluster size distributions produced in the sensitive volume of an ion-counting wall-less nanodosimeter by monoenergetic carbon ions with energies between 45 MeV and 150 MeV were measured at the TANDEM-ALPI ion accelerator facility complex of the LNL-INFN in Legnaro. Those produced by monoenergetic helium ions with energies between 2 MeV and 20 MeV were measured at the accelerator facilities of PTB and with a 241Am alpha particle source. C3H8 was used as the target gas. The ionization cluster size distributions were measured in narrow beam geometry with the primary beam passing the target volume at specified distances from its centre, and in broad beam geometry with a fan-like primary beam. By applying a suitable drift time window, the effective size of the target volume was adjusted to match the size of a DNA segment. The measured data were compared with the results of simulations obtained with the PTB Monte Carlo code PTra. Before the comparison, the simulated cluster size distributions were corrected with respect to the background of additional ionizations produced in the transport system of the ionized target gas molecules. Measured and simulated characteristics of the particle track structure are in good agreement for both types of primary particles and for both types of the irradiation geometry. As the range in tissue of the ions investigated is within the typical extension of a spread-out Bragg peak, these data are useful for benchmarking not only ‘general purpose’ track structure simulation codes, but also treatment planning codes used in hadron therapy. Additionally, these data sets may serve as a data base for codes modelling the induction of radiation damages at the DNA-level as they almost completely characterize the ionization component of the nanometric track structure.
Ultralow energy ion beam surface modification of low density polyethylene.
Shenton, Martyn J; Bradley, James W; van den Berg, Jaap A; Armour, David G; Stevens, Gary C
2005-12-01
Ultralow energy Ar+ and O+ ion beam irradiation of low density polyethylene has been carried out under controlled dose and monoenergetic conditions. XPS of Ar+-treated surfaces exposed to ambient atmosphere show that the bombardment of 50 eV Ar+ ions at a total dose of 10(16) cm(-2) gives rise to very reactive surfaces with oxygen incorporation at about 50% of the species present in the upper surface layer. Using pure O+ beam irradiation, comparatively low O incorporation is achieved without exposure to atmosphere (approximately 13% O in the upper surface). However, if the surface is activated by Ar+ pretreatment, then large oxygen contents can be achieved under subsequent O+ irradiation (up to 48% O). The results show that for very low energy (20 eV) oxygen ions there is a dose threshold of about 5 x 10(15) cm(-2) before surface oxygen incorporation is observed. It appears that, for both Ar+ and O+ ions in this regime, the degree of surface modification is only very weakly dependent on the ion energy. The results suggest that in the nonequilibrium plasma treatment of polymers, where the ion flux is typically 10(18) m(-2) s(-1), low energy ions (<50 eV) may be responsible for surface chemical modification.
Neutral dynamics and ion energy transport in MST plasma
NASA Astrophysics Data System (ADS)
Xing, Zichuan; Nornberg, Mark; den Hartog, Daniel; Kumar, Santosh; Anderson, Jay
2015-11-01
Neutral dynamics can have a significant effect on ion energy transport through charge exchange collisions. Whereas previously charge exchange was considered a direct loss mechanism in MST plasmas, new analysis indicates that significant thermal charge exchange neutrals are reionized. Further, the temperatures of the neutral species in the core of the plasma are suspected to be much higher than room temperature, which has a large effect on ion energy losses due to charge exchange. The DEGAS2 Monte Carlo simulation code is applied to the MST reversed field pinch experiment to estimate the density and temperature profile of the neutral species. The result is then used to further examine the effect of the neutral species on ion energy transport in improved confinement plasmas. This enables the development of a model that accounts for collisional equilibration between species, classical convective and conductive energy transport, and energy loss due to charge exchange collisions. The goal is to quantify classical, stochastic, and anomalous ion heating and transport in RFP plasmas. Work supported by the US DOE. DEGAS2 is provided by PPPL and STRAHL is provided by Ralph Dux of the Max-Planck-Institut fur Plasmaphysik.
NASA Astrophysics Data System (ADS)
Tamboli, Sumedha; Dhoble, S. J.
2017-09-01
Phototherapy is a renowned treatment for curing skin diseases since ancient times. Phototherapeutic treatment for psoriasis and many other diseases require narrow band ultra violet-B (NB-UVB) light with peak intensity at 313 nm to be exposed to the affected part of body. In this paper, we report combustion synthesis of NB-UVB - 313 nm emitting Ca9Mg(PO4)6F2 phosphors doped with Gd3 +, Pr3 + and Li+ ions. The phase formation was confirmed by obtaining X-ray diffraction (XRD) pattern and morphology was studied with the Scanning electron microscopy (SEM) images. Photoluminescence (PL) emission spectra show intense narrow band emission at 313 nm under 274 nm excitation wavelengths. Emission intensity was enhanced when Ca9Mg(PO4)6F2 compound is co-doped with Pr3 + ions. Excitation spectra of Ca9Mg(PO4)6F2:Gd3 +, Pr3 + doped samples shows broad excitation in ultra violet C (UVC) region. Diffuse reflectance spectra (DRS), obtained by UV-visible spectrophotometer, measures the absorption properties of the material. By applying Kubelka Munk function on the diffuse reflectance spectra, band gap of the material is determined. PL decay curves were examined which indicates efficient energy transfer between Pr3 + and Gd3 + ions. Charge compensation effect was also studied by co-doping Li+ ion in host. Emission intensity was found to increase with the addition of charge compensator. The prepared phosphor has potential to convert UVC light into NB-UVB. The luminescence intensity of Gd3 + shows remarkable increase when it is sensitized with Pr3 +, and an addition of charge compensator in the form of Li+, show even better results. This phosphor surely has the potential to be used as phototherapy lamp phosphor.
Materials modification using ions with energies below 1 MeV/u
NASA Astrophysics Data System (ADS)
Karlušić, M.; Jakšić, M.; Buljan, M.; Sancho-Parramon, J.; Bogdanović-Radović, I.; Radić, N.; Bernstorff, S.
2013-12-01
Materials modifications using swift heavy ion beams provided by large scale accelerators have been used for many years in a wide variety of ways, e.g. to produce ion tracks or to modify the shape of nanoparticles. In all those applications the most relevant parameter for the materials modification is the electronic stopping power and not the ion kinetic energy. For many materials, ions with energies below 1 MeV/u delivered from medium and small size accelerators have already sufficiently high electronic stopping power to modify materials in different ways. Also, in this energy range the nuclear stopping power can be large enough to provide additional opportunities for materials modifications. In the present paper, we review recent experimental activities of the Zagreb group where ion beams with energies below 1 MeV/u, obtained from a 6 MV EN Tandem Van de Graaff accelerator have been used. Additionally, we present several novel examples of materials modifications and their analysis with such ion beams.
Ion collector design for an energy recovery test proposal with the negative ion source NIO1
DOE Office of Scientific and Technical Information (OSTI.GOV)
Variale, V., E-mail: vincenzo.variale@ba.infn.it; Cavenago, M.; Agostinetti, P.
2016-02-15
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{sup −} beam from a negative ion source is partially neutralized by a gas cell, which leaves more than 40% of energy in residual beams (D{sup −} and D{sup +}), so that an ion beammore » energy recovery system can significantly contribute to optimize efficiency. Recently, the test negative ion source NIO1 (60 keV, 9 beamlets with 15 mA H{sup −} 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.« less
Peter, Christine; Hummer, Gerhard
2005-01-01
Narrow hydrophobic regions are a common feature of biological channels, with possible roles in ion-channel gating. We study the principles that govern ion transport through narrow hydrophobic membrane pores by molecular dynamics simulation of model membranes formed of hexagonally packed carbon nanotubes. We focus on the factors that determine the energetics of ion translocation through such nonpolar nanopores and compare the resulting free-energy barriers for pores with different diameters corresponding to the gating regions in closed and open forms of potassium channels. Our model system also allows us to compare the results from molecular dynamics simulations directly to continuum electrostatics calculations. Both simulations and continuum calculations show that subnanometer wide pores pose a huge free-energy barrier for ions, but a small increase in the pore diameter to ∼1 nm nearly eliminates that barrier. We also find that in those wider channels the ion mobility is comparable to that in the bulk phase. By calculating local electrostatic potentials, we show that the long range Coulomb interactions of ions are strongly screened in the wide water-filled channels. Whereas continuum calculations capture the overall energetics reasonably well, the local water structure, which is not accounted for in this model, leads to interesting effects such as the preference of hydrated ions to move along the pore wall rather than through the center of the pore. PMID:16006629
Graded bit patterned magnetic arrays fabricated via angled low-energy He ion irradiation.
Chang, L V; Nasruallah, A; Ruchhoeft, P; Khizroev, S; Litvinov, D
2012-07-11
A bit patterned magnetic array based on Co/Pd magnetic multilayers with a binary perpendicular magnetic anisotropy distribution was fabricated. The binary anisotropy distribution was attained through angled helium ion irradiation of a bit edge using hydrogen silsesquioxane (HSQ) resist as an ion stopping layer to protect the rest of the bit. The viability of this technique was explored numerically and evaluated through magnetic measurements of the prepared bit patterned magnetic array. The resulting graded bit patterned magnetic array showed a 35% reduction in coercivity and a 9% narrowing of the standard deviation of the switching field.
High-energy accelerator for beams of heavy ions
Martin, Ronald L.; Arnold, Richard C.
1978-01-01
An apparatus for accelerating heavy ions to high energies and directing the accelerated ions at a target comprises a source of singly ionized heavy ions of an element or compound of greater than 100 atomic mass units, means for accelerating the heavy ions, a storage ring for accumulating the accelerated heavy ions and switching means for switching the heavy ions from the storage ring to strike a target substantially simultaneously from a plurality of directions. In a particular embodiment the heavy ion that is accelerated is singly ionized hydrogen iodide. After acceleration, if the beam is of molecular ions, the ions are dissociated to leave an accelerated singly ionized atomic ion in a beam. Extraction of the beam may be accomplished by stripping all the electrons from the atomic ion to switch the beam from the storage ring by bending it in magnetic field of the storage ring.
Ions in water: Free energies, surface effects, and geometrical constraints
NASA Astrophysics Data System (ADS)
Herce, Henry David
In this work, we present our results for ion solvation in finite and infinite water clusters. Molecular Dynamic simulations are used to connect the fundamental macroscopic quantities such as free energy, internal energy and entropy with the underlying microscopic description. Molecular dynamics studies complement experimental results and lead to a deeper insight into the solvation and diffusion of ionic species. Beyond its intrinsic interest, the ion solvation problem has practical relevance because of its role as ideal model system with which to construct and test ion-water interaction potentials. The ionic charging free energy is a very sensitive probe for the treatment of electrostatics in any given simulation setting. In this work, we present methods to compute the ionic charging free energy in systems characterized by atomic charges, and higher-order multipoles, mainly dipoles and quadrupoles. The results of these methods under periodic boundary conditions and spherical boundary conditions are then compared. For the treatment of spherical boundary conditions, we introduce a generalization of Gauss' law that links the microscopic variables to the relevant thermodynamic quantities. Ionic solvation in finite clusters is a problem relevant for many areas of chemistry and biology, such as the gas-liquid interface of tropospheric aerosol particles, or the interphase between water and proteins, membranes, etc. Careful evaluations of the free energy, internal energy and entropy are used to address controversial or unresolved issues, related to the underlying physical cause of surface solvation, and the basic assumptions that go with it. Our main conclusions are the following: (i) The main cause of surface solvation of a single ion in a water cluster is both water and ion polarization, coupled to the charge and size of the ion. Interestingly, the total energy of the ion increases near the cluster surface, while the total energy of water decreases. Also, our analysis
Study on ion energy distribution in low-frequency oscillation time scale of Hall thrusters
NASA Astrophysics Data System (ADS)
Wei, Liqiu; Li, Wenbo; Ding, Yongjie; Han, Liang; Yu, Daren; Cao, Yong
2017-11-01
This paper reports on the dynamic characteristics of the distribution of ion energy during Hall thruster discharge in the low-frequency oscillation time scale through experimental studies, and a statistical analysis of the time-varying peak and width of ion energy and the ratio of high-energy ions during the low-frequency oscillation. The results show that the ion energy distribution exhibits a periodic change during the low-frequency oscillation. Moreover, the variation in the ion energy peak is opposite to that of the discharge current, and the variations in width of the ion energy distribution and the ratio of high-energy ions are consistent with that of the discharge current. The variation characteristics of the ion density and discharge potential were simulated by one-dimensional hybrid-direct kinetic simulations; the simulation results and analysis indicate that the periodic change in the distribution of ion energy during the low-frequency oscillation depends on the relationship between the ionization source term and discharge potential distribution during ionization in the discharge channel.
Kinetic energies of fragment ions produced by dissociative photoionization of NO
NASA Technical Reports Server (NTRS)
Samson, J. A. R.; Angel, G. C.; Rstgi, O. P.
1985-01-01
The kinetic energies of ions produced by dissociative photoionization of NO have been measured at the discrete resonance lines of He (584A) and Ne (736A), and with undispersed synchrotron radiation. O sup + ions were identified with energies from 0 to approximately 0.5 eV and two groups of N sup + ions one with energy of 0.36 eV and another with energies between 0.9 and 1.5 eV, apparently produced by predissociation of the C sup 3 P 1 and B'1 sigma states respectively.
Ion componsition of zipper events
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kaye, S.M.; Shelley, E.G.; Sharp, R.D.
1981-05-01
A class of ion distributions has recently been identified by Fennell et al. (this issue). The distributions are composed of two components, a low-energy component with peak fluxes directed along the field line and a high-energy component with peak fluxes in the perpendicular direction. The transiton between the two components occur over a very narrow range of energies but can occur anywhere between approximately several hundred electron volts and 20 keV. Because of the appearance of this distribution on an energy versus time spectrogram, the ion events have been called zippers. The purpose of this report is to examine themore » mass composition of the zipper events. We find that the low-energy and parallel component is composed primarily of O/sup +/, with, to a lesser degree, H/sup +/ and a trace of He/sup +/. The high-energy and perpendicular component is predominantly H/sup +/, with the relative abundances of O/sup +/ and He/sup +/ down from those of the low-energy component by a factor of approx.10. These results suggest that whereas the low-energy component is probably ionospheric in origin, the source of the high-energy components is most probably the plsamasheet.« less
High Energy Ion Acceleration by Extreme Laser Radiation Pressure
2017-03-14
and was published in Nuclear Instruments and Methods A [11]. For similar targets, it was found that by monitoring the divergence of a low- energy ...AFRL-AFOSR-UK-TR-2017-0015 High energy ion acceleration by extreme laser radiation pressure Paul McKenna UNIVERSITY OF STRATHCLYDE VIZ ROYAL COLLEGE...MM-YYYY) 14-03-2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) 01 May 2013 to 31 Dec 2016 4. TITLE AND SUBTITLE High energy ion acceleration
Qiu, Bao; Yin, Chong; Xia, Yonggao; Liu, Zhaoping
2017-02-01
As rechargeable Li-ion batteries have expanded their applications into on-board energy storage for electric vehicles, the energy and power must be increased to meet the new demands. Li-rich layered oxides are one of the most promising candidate materials; however, it is very difficult to make them compatible with high volumetric energy density and power density. Here, we develop an innovative approach to synthesize three-dimensional (3D) nanoporous Li-rich layered oxides Li[Li 0.144 Ni 0.136 Co 0.136 Mn 0.544 ]O 2 , directly occurring at deep chemical delithiation with carbon dioxide. It is found that the as-prepared material presents a micrometer-sized spherical structure that is typically composed of interconnected nanosized subunits with narrow distributed pores at 3.6 nm. As a result, this unique 3D micro-/nanostructure not only has a high tap density over 2.20 g cm -3 but also exhibits excellent rate capability (197.6 mA h g -1 at 1250 mA g -1 ) as an electrode. The excellent electrochemical performance is ascribed to the unique nanoporous micro-nanostructures, which facilitates the Li + diffusion and enhances the structural stability of the Li-rich layered cathode materials. Our work offers a comprehensive designing strategy to construct 3D nanoporous Li-rich layered oxides for both high volumetric energy density and power density in Li-ion batteries.
Low-energy ion beamline scattering apparatus for surface science investigations
NASA Astrophysics Data System (ADS)
Gordon, M. J.; Giapis, K. P.
2005-08-01
We report on the design, construction, and performance of a high current (monolayers/s), mass-filtered ion beamline system for surface scattering studies using inert and reactive species at collision energies below 1500 eV. The system combines a high-density inductively coupled plasma ion source, high-voltage floating beam transport line with magnet mass-filter and neutral stripping, decelerator, and broad based detection capabilities (ions and neutrals in both mass and energy) for products leaving the target surface. The entire system was designed from the ground up to be a robust platform to study ion-surface interactions from a more global perspective, i.e., high fluxes (>100μA/cm2) of a single ion species at low, tunable energy (50-1400±5eV full width half maximum) can be delivered to a grounded target under ultrahigh vacuum conditions. The high current at low energy problem is solved using an accel-decel transport scheme where ions are created at the desired collision energy in the plasma source, extracted and accelerated to high transport energy (20 keV to fight space charge repulsion), and then decelerated back down to their original creation potential right before impacting the grounded target. Scattered species and those originating from the surface are directly analyzed in energy and mass using a triply pumped, hybrid detector composed of an electron impact ionizer, hemispherical electrostatic sector, and rf/dc quadrupole in series. With such a system, the collision kinematics, charge exchange, and chemistry occurring on the target surface can be separated by fully analyzing the scattered product flux. Key design aspects of the plasma source, beamline, and detection system are emphasized here to highlight how to work around physical limitations associated with high beam flux at low energy, pumping requirements, beam focusing, and scattered product analysis. Operational details of the beamline are discussed from the perspective of available beam current
DOE Office of Scientific and Technical Information (OSTI.GOV)
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.
Balance functions have been measured in terms of relative pseudorapidity ( Δη ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider (RHIC) from Au + Au collisions atmore » $$\\sqrt{s}$$$_{NN}$$ = 7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at $$\\sqrt{s}$$$_{NN}$$ = 2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). Finally, the narrowing of the balance function in central collisions at $$\\sqrt{s}$$$_{NN}$$ = 7.7 GeV implies that a QGP is still being created at this relatively low energy.« less
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...
2016-08-16
Balance functions have been measured in terms of relative pseudorapidity ( Δη ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider (RHIC) from Au + Au collisions atmore » $$\\sqrt{s}$$$_{NN}$$ = 7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at $$\\sqrt{s}$$$_{NN}$$ = 2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). Finally, the narrowing of the balance function in central collisions at $$\\sqrt{s}$$$_{NN}$$ = 7.7 GeV implies that a QGP is still being created at this relatively low energy.« less
Density functional theory study of the capacitance of single file ions in a narrow cylinder
Kong, Xian; Wu, Jianzhong; Henderson, Douglas
2014-11-14
In this paper, the differential capacitance of a model organic electrolyte in a cylindrical pore that is so narrow that the ions can form only a single file is studied by means of density functional theory (DFT). Kornyshev (2013), has studied this system and found the differential capacitance to have only a double hump shape (the so-called camel shape) whereas other geometries show this behavior only at low ionic concentrations that are typical for aqueous electrolytes. However, his calculation is rather approximate. In this DFT study we find that the double hump shape occurs only at low ionic concentrations. Atmore » high concentrations, the capacitance has only a single hump. Kornyshev considers a metallic cylinder and approximately includes the contributions of electrostatic images. Electrostatic images are not easily incorporated into DFT. In conclusion, images are not considered in this study and the question of whether Kornyshev’s result is due to his approximations or images cannot be answered. Simulations to answer this question are planned.« less
NASA Astrophysics Data System (ADS)
Meot-Ner (Mautner), Michael; Somogyi, Árpád
2007-11-01
The internal energies of dissociating ions, activated chemically or collisionally, can be estimated using the kinetics of thermal dissociation. The thermal Arrhenius parameters can be combined with the observed dissociation rate of the activated ions using kdiss = Athermalexp(-Ea,thermal/RTeff). This Arrhenius-type relation yields the effective temperature, Teff, at which the ions would dissociate thermally at the same rate, or yield the same product distributions, as the activated ions. In turn, Teff is used to calculate the internal energy of the ions and the energy deposited by the activation process. The method yields an energy deposition efficiency of 10% for a chemical ionization proton transfer reaction and 8-26% for the surface collisions of various peptide ions. Internal energies of ions activated by chemical ionization or by gas phase collisions, and of ions produced by desorption methods such as fast atom bombardment, can be also evaluated. Thermal extrapolation is especially useful for ion-molecule reaction products and for biological ions, where other methods to evaluate internal energies are laborious or unavailable.
Superstatistical Energy Distributions of an Ion in an Ultracold Buffer Gas
NASA Astrophysics Data System (ADS)
Rouse, I.; Willitsch, S.
2017-04-01
An ion in a radio frequency ion trap interacting with a buffer gas of ultracold neutral atoms is a driven dynamical system which has been found to develop a nonthermal energy distribution with a power law tail. The exact analytical form of this distribution is unknown, but has often been represented empirically by q -exponential (Tsallis) functions. Based on the concepts of superstatistics, we introduce a framework for the statistical mechanics of an ion trapped in an rf field subject to collisions with a buffer gas. We derive analytic ion secular energy distributions from first principles both neglecting and including the effects of the thermal energy of the buffer gas. For a buffer gas with a finite temperature, we prove that Tsallis statistics emerges from the combination of a constant heating term and multiplicative energy fluctuations. We show that the resulting distributions essentially depend on experimentally controllable parameters paving the way for an accurate control of the statistical properties of ion-atom hybrid systems.
NASA Astrophysics Data System (ADS)
Liang, Jun; Donovan, E.; Ni, B.; Yue, C.; Jiang, F.; Angelopoulos, V.
2014-10-01
Ion precipitation mechanisms are usually energy dependent and contingent upon magnetospheric/ionospheric locations. Therefore, the pattern of energy-latitude dependence of ion precipitation boundaries seen by low Earth orbit satellites can be implicative of the mechanism(s) underlying the precipitation. The pitch angle scattering of ions led by the field line curvature, a well-recognized mechanism of ion precipitation in the central plasma sheet (CPS), leads to one common pattern of energy-latitude dispersion, in that the ion precipitation flux diminishes at higher (lower) latitudes for protons with lower (higher) energies. In this study, we introduce one other systematically existing pattern of energy-latitude dispersion of ion precipitation, in that the lower energy ion precipitation extends to lower latitude than the higher-energy ion precipitation. Via investigating such a "reversed" energy-latitude dispersion pattern, we explore possible mechanisms of ion precipitation other than the field line curvature scattering. We demonstrate via theories and simulations that the H-band electromagnetic ion cyclotron (EMIC) wave is capable of preferentially scattering keV protons in the CPS and potentially leads to the reversed energy-latitude dispersion of proton precipitation. We then present detailed event analyses and provide support to a linkage between the EMIC waves in the equatorial CPS and ion precipitation events with reversed energy-latitude dispersion. We also discuss the role of ion acceleration in the topside ionosphere which, together with the CPS ion population, may result in a variety of energy-latitude distributions of the overall ion precipitation.
Observation of a high-energy tail in ion energy distribution in the cylindrical Hall thruster plasma
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lim, Youbong; Kim, Holak; Choe, Wonho, E-mail: wchoe@kaist.ac.kr
2014-10-15
A novel method is presented to determine populations and ion energy distribution functions (IEDFs) of individual ion species having different charge states in an ion beam from the measured spectrum of an E × B probe. The inversion of the problem is performed by adopting the iterative Tikhonov regularization method with the characteristic matrices obtained from the calculated ion trajectories. In a cylindrical Hall thruster plasma, an excellent agreement is observed between the IEDFs by an E × B probe and those by a retarding potential analyzer. The existence of a high-energy tail in the IEDF is found to be mainly due to singlymore » charged Xe ions, and is interpreted in terms of non-linear ion acceleration.« less
NASA Astrophysics Data System (ADS)
Ohtani, S.; Nose, M.; Miyashita, Y.; Lui, A.
2014-12-01
We investigate the responses of different ion species (H+, He+, He++, and O+) to fast plasma flows and local dipolarization in the plasma sheet in terms of energy density. We use energetic (9-210 keV) ion composition measurements made by the Geotail satellite at r = 10~31 RE. The results are summarized as follows: (1) whereas the O+-to-H+ ratio decreases with earthward flow velocity, it increases with tailward flow velocity with Vx dependence steeper for perpendicular flows than for parallel flows; (2) for fast earthward flows, the energy density of each ion species increases without any clear preference for heavy ions; (3) for fast tailward flows the ion energy density increases initially, then it decreases to below pre-flow levels except for O+; (4) the O+-to-H+ ratio does not increase through local dipolarization irrespective of dipolarization amplitude, background BZ, X distance, and VX; (5) in general, the H+ and He++ ions behave similarly. Result (1) can be attributed to radial transport along with the earthward increase of the background O+-to-H+ ratio. Results (2) and (4) indicate that ion energization associated with local dipolarization is not mass-dependent possibly because in the energy range of our interest the ions are not magnetized irrespective of species. In the tailward outflow region of reconnection, where the plasma sheet becomes thinner, the H+ ions escape along the field line more easily than the O+ ions, which possibly explains result (3). Result (5) suggests that the solar wind is the primary source of the high-energy H+ ions.
NASA Astrophysics Data System (ADS)
Scandale, W.; Taratin, A. M.; Kovalenko, A. D.
2013-01-01
The paper presents the current status with the use of the crystal defectors for high energy ion beams. The channeling properties of multicharged ions are discussed. The results of the experiments on the deflection and extraction (collimation) of high energy ion beams with bent crystals performed in the accelerator centers are shortly considered. The analysis of the recent collimation experiment with a Pb nuclei of 270GeV/c per charge at the CERN Super Proton Synchrotron showed that the channeling efficiency was as large as about 90%. For Pb ions of the LHC energies a new mechanism, which can reduce the channeling efficiency, appears. The electromagnetic dissociation (ED) becomes possible for well channeled particles. However, the estimations performed in the paper show that the ED probability is small and should not visibly reduce the collimation efficiency. On the other hand, the aligned crystal gives the possibility to study the ED processes of heavy nuclei in the conditions when nuclear interactions are fully suppressed.
NASA Astrophysics Data System (ADS)
Szegö, Karoly; Nemeth, Zoltan; Foldy, Lajos; Burch, James L.; Goldstein, Raymond; Mandt, Kathleen; Mokashi, Prachet; Broiles, Tom
2015-04-01
The Ion Electron Sensor (IES) simultaneously measures ions and electrons with two separate electrostatic plasma analyzers in the energy range of 4 eV- 22 keV for ions. The field of view is 90ox360o, with angular resolution 5ox45o for ions, with a sector containing the solar wind being further segmented to 5o × 5o. IES has operated continuously since early 2014. In the ion data a low energy (<50-100 eV) component is well separated from the higher energy ions. Here we analyze the arrival direction of this low energy component. The origin of these low energy ions is certainly the ionized component of the neutral gas emitted due to solar activity from comet 67P/Churiumov-Gerasimenko. The low energy component in general shows a 6h periodicity due to cometary rotation. The data show, however, that the arrival direction of the low energy ions is smeared both in azimuth and elevation, due possibly to the diverse mechanisms affecting these ions. One of these effects is the spacecraft potential (~-10V), which accelerates the ions towards the spacecraft omnidirectionally. To characterize the flow direction in azimuth-elevation, we have integrated over the lowest 8 energy channels using weighted energy: sum(counts * energy)/sum(counts); and considered only cases when the counts are above 30. When we apply higher cut for counts, the flow direction became more definite. For this analysis we use data files where the two neighbouring energy values and elevation values are collapsed; and the azimuthal resolution is 45o, that is the solar wind azimuthal segmentation is also collapsed. Here we use day 2014.09.11. as illustration. On that day a solar wind shock reached the spacecraft at about ~10 UT. After the shock transition the energy of the solar wind became higher, and after ~12 UT the flow direction of the solar wind fluctuated, sometimes by 35o. On this day Rosetta flew at about 29.3-29.6 km from the nucleus. In the azimuth-elevation plots summed over "weighted energy" (as
Feasibility of a 90° electric sector energy analyzer for low energy ion beam characterization
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mahinay, C. L. S., E-mail: cmahinay@nip.upd.edu.ph; Ramos, H. J.; Wada, M.
2015-02-15
A simple formula to calculate refocusing by locating the output slit at a specific distance away from the exit of 90° ion deflecting electric sector is given. Numerical analysis is also performed to calculate the ion beam trajectories for different values of the initial angular deviation of the beam. To validate the theory, a compact (90 mm × 5.5 mm × 32 mm) 90° sector ESA is fabricated which can fit through the inner diameter of a conflat 70 vacuum flange. Experimental results show that the dependence of resolution upon the distance between the sector exit and the Faraday cupmore » agrees with the theory. The fabricated 90° sector electrostatic energy analyzer was then used to measure the space resolved ion energy distribution functions of an ion beam with the energy as low as 600 eV.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yang, Zhaoqing; Wang, Taiping; Copping, Andrea E.
Understanding and providing proactive information on the potential for tidal energy projects to cause changes to the physical system and to key water quality constituents in tidal waters is a necessary and cost-effective means to avoid costly regulatory involvement and late stage surprises in the permitting process. This paper presents a modeling study for evaluating the tidal energy extraction and its potential impacts on the marine environment in a real world site - Tacoma Narrows of Puget Sound, Washington State, USA. An unstructured-grid coastal ocean model, fitted with a module that simulates tidal energy devices, was applied to simulate themore » tidal energy extracted by different turbine array configurations and the potential effects of the extraction at local and system-wide scales in Tacoma Narrows and South Puget Sound. Model results demonstrated the advantage of an unstructured-grid model for simulating the far-field effects of tidal energy extraction in a large model domain, as well as assessing the near-field effect using a fine grid resolution near the tidal turbines. The outcome shows that a realistic near-term deployment scenario extracts a very small fraction of the total tidal energy in the system and that system wide environmental effects are not likely; however, near-field effects on the flow field and bed shear stress in the area of tidal turbine farm are more likely. Model results also indicate that from a practical standpoint, hydrodynamic or water quality effects are not likely to be the limiting factor for development of large commercial-scale tidal farms. Results indicate that very high numbers of turbines are required to significantly alter the tidal system; limitations on marine space or other environmental concerns are likely to be reached before reaching these deployment levels. These findings show that important information obtained from numerical modeling can be used to inform regulatory and policy processes for tidal energy
The Narrow-Line Region of Narrow-Line Seyfert 1 Galaxies
NASA Astrophysics Data System (ADS)
Rodríguez-Ardila, A.; Binette, Luc; Pastoriza, Miriani G.; Donzelli, Carlos J.
2000-08-01
This work studies the optical emission-line properties and physical conditions of the narrow-line region (NLR) of seven narrow-line Seyfert 1 galaxies (NLS1's) for which high signal-to-noise ratio spectroscopic observations were available. The resolution is 340 km s-1 (at Hα) over the wavelength interval 3700-9500 Å, enabling us to separate the broad and narrow components of the permitted emission lines. Our results show that the flux carried out by the narrow component of Hβ is, on average, 50% of the total line flux. As a result, the [O III] λ5007/Hβ ratio emitted in the NLR varies from 1 to 5, instead of the universally adopted value of 10. This has strong implications for the required spectral energy distribution that ionizes the NLR gas. Photoionization models that consider a NLR composed of a combination of matter-bounded and ionization-bounded clouds are successful at explaining the low [O III] λ5007/Hβ ratio and the weakness of low-ionization lines of NLS1's. Variation of the relative proportion of these two type of clouds nicely reproduces the dispersion of narrow-line ratios found among the NLS1 sample. Assuming similar physical model parameters of both NLS1's and the normal Seyfert 1 galaxy NGC 5548, we show that the observed differences of emission-line ratios between these two groups of galaxies can be explained, to a first approximation, in terms of the shape of the input ionizing continuum. Narrow emission-line ratios of NLS1's are better reproduced by a steep power-law continuum in the EUV-soft X-ray region, with spectral index α~-2. Flatter spectral indices (α~-1.5) match the observed line ratios of NGC 5548 but are unable to provide a good match to the NLS1 ratios. This result is consistent with ROSAT observations of NLS1's, which show that these objects are characterized by steeper power-law indices than those of Seyfert 1 galaxies with strong broad optical lines. Based on observations made at CASLEO. Complejo Astronómico El Leoncito
Optical characterization of poly(methyl methacrylate) implanted with low energy ions
NASA Astrophysics Data System (ADS)
Gupta, Renu; Kumar, Vijay; Goyal, Parveen Kumar; Kumar, Shyam
2012-12-01
The samples of poly(methyl methacrylate) (PMMA) were subjected to 100 keV N+ and Ar+ ion implantation up to a maximum fluence of 2 × 1016 ions/cm2. The effect of ion implantation on the optical energy gap and the refractive index has been studied through UV-visible spectroscopy. The results clearly indicate a decrease in the values of optical energy gap and an increase in the values of refractive index as an effect of ion implantation corresponding to both of the ions. It has also been observed that the changes induced by the implanted ions are more pronounced for N+ ions in comparison to Ar+ ions. This variation has been correlated with the calculated ranges of these ions in PMMA polymer using Stopping and Range of Ions in Matter (SRIM) code. Finally, an attempt has been made to correlate all the observed changes with the induced structural changes as revealed through Raman spectroscopy.
Spectral Engineering of Slow Light, Cavity Line Narrowing, and Pulse Compression
NASA Astrophysics Data System (ADS)
Sabooni, Mahmood; Li, Qian; Rippe, Lars; Mohan, R. Krishna; Kröll, Stefan
2013-11-01
More than 4 orders of magnitude of cavity-linewidth narrowing in a rare-earth-ion-doped crystal cavity, emanating from strong intracavity dispersion caused by off-resonant interaction with dopant ions, is demonstrated. The dispersion profiles are engineered using optical pumping techniques creating significant semipermanent but reprogrammable changes of the rare-earth absorption profiles. Several cavity modes are shown within the spectral transmission window. Several possible applications of this phenomenon are discussed.
The role of electronic energy loss in ion beam modification of materials
Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; ...
2014-10-05
The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less
Neutral beamline with ion energy recovery based on magnetic blocking of electrons
Stirling, William L.
1982-01-01
A neutral beamline generator with energy recovery of the full-energy ion ponent of the beam based on magnetic blocking of electrons is provided. Ions from a positive ion source are accelerated to the desired beam energy from a slightly positive potential level with respect to ground through a neutralizer cell by means of a negative acceleration voltage. The unneutralized full-energy ion component of the beam exiting the neutralizer are retarded and slightly deflected and the electrons in the neutralizer are blocked by a magnetic field generated transverse to the beamline. An electron collector in the form of a coaxial cylinder surrounding and protruding axial a few centimeters beyond the neutralizer exit terminates the electrons which exit the neutralizer in an E x B drift to the collector when the collector is biased a few hundred volts positive with respect to the neutralizer voltage. The neutralizer is operated at the negative acceleration voltage, and the deflected full energy ions are decelerated and the charge collected at ground potential thereby expending none of their energy received from the acceleration power supply.
Model for Cumulative Solar Heavy Ion Energy and LET Spectra
NASA Technical Reports Server (NTRS)
Xapsos, Mike; Barth, Janet; Stauffer, Craig; Jordan, Tom; Mewaldt, Richard
2007-01-01
A probabilistic model of cumulative solar heavy ion energy and lineary energy transfer (LET) spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions.
Hentz, A; Parkinson, G S; Quinn, P D; Muñoz-Márquez, M A; Woodruff, D P; Grande, P L; Schiwietz, G; Bailey, P; Noakes, T C Q
2009-03-06
The energy spectrum associated with scattering of 100 keV H+ ions from the outermost few atomic layers of Cu(111) in different scattering geometries provides direct evidence of trajectory-dependent electronic energy loss. Theoretical simulations, combining standard Monte Carlo calculations of the elastic scattering trajectories with coupled-channel calculations to describe inner-shell ionization and excitation as a function of impact parameter, reproduce the effects well and provide a means for far more complete analysis of medium-energy ion scattering data.
Ion Energy and Ion Flux Distributions of CF4/Ar/O2 Inductively Coupled Plasmas in a GEC Cell
NASA Technical Reports Server (NTRS)
Rao, M. V. V. S.; Cruden, Brett; Sharma, Surendra; Meyyappan, Meyya
2001-01-01
Knowledge of ion kinetics in plasma processing gas mixtures, such as CF4:Ar:O2, is important for understanding plasma assisted etching and deposition of materials. Ion energies and ion fluxes were measured in this mixture for 80:10:10, 60:20:20, and 40:30:30 mixture ratios in the pressure range of 10-50 mTorr, and at 200 and 300 W of RF power. Ions from plasma, sampled through a 10 micron orifice in the center of the lower plane electrode, were energy and mass analyzed by a combination of electrostatic energy and quadrupole mass filters. CFx(+) (x = 1 - 3), F2(+), F(+), C(+) from CF4, Ar(+) from Ar, and O2(+) and O(+) from O2, and by-product ions SiFx(+)(x = 1 - 3) from etching of quartz coupling window, COFx(+)(x = 1 - 3), CO(+), CO2(+), and OF(+) were detected. In all conditions ion flux decreases with increase of pressure but increase with increase of RF power. Ar(+) signal decreases with increase of pressure while CF3(+), which is the dominant ion at all conditions, increases with increase in pressure. The loss mechanism for Ar(+) and increase of CF3(+) is due to large cross section for Ar(+) + CF4 yields Ar + CF3(+) + F. Ion energies, which range from 15-25 eV depending on plasma operating conditions, are nearly Gaussian. By-product ion signals are higher at lower pressures indicating stronger plasma interaction with quartz window.
A Green's function method for high charge and energy ion transport.
Chun, S Y; Khandelwal, G S; Wilson, J W
1996-02-01
A heavy-ion transport code using Green's function methods is developed. The low-order perturbation terms exhibiting the greatest energy variation are used as dominant energy-dependent terms, and the higher order collision terms are evaluated using nonperturbative methods. The recently revised NUCFRG database is used to evaluate the solution for comparison with experimental data for 625A MeV 20Ne and 517A MeV 40Ar ion beams. Improved agreements with the attenuation characteristics for neon ions are found, and reasonable agreement is obtained for the transport of argon ions in water.
Systematic investigations of low energy Ar ion beam sputtering of Si and Ag
NASA Astrophysics Data System (ADS)
Feder, R.; Frost, F.; Neumann, H.; Bundesmann, C.; Rauschenbach, B.
2013-12-01
Ion beam sputter deposition (IBD) delivers some intrinsic features influencing the growing film properties, because ion properties and geometrical process conditions generate different energy and spatial distributions of the sputtered and scattered particles. Even though IBD has been used for decades, the full capabilities are not investigated systematically and specifically used yet. Therefore, a systematic and comprehensive analysis of the correlation between the properties of the ion beam, the generated secondary particles and backscattered ions and the deposited films needs to be done.A vacuum deposition chamber has been set up which allows ion beam sputtering of different targets under variation of geometrical parameters (ion incidence angle, position of substrates and analytics in respect to the target) and of ion beam parameters (ion species, ion energy) to perform a systematic and comprehensive analysis of the correlation between the properties of the ion beam, the properties of the sputtered and scattered particles, and the properties of the deposited films. A set of samples was prepared and characterized with respect to selected film properties, such as thickness and surface topography. The experiments indicate a systematic influence of the deposition parameters on the film properties as hypothesized before. Because of this influence, the energy distribution of secondary particles was measured using an energy-selective mass spectrometer. Among others, experiments revealed a high-energetic maximum for backscattered primary ions, which shifts with increasing emission angle to higher energies. Experimental data are compared with Monte Carlo simulations done with the well-known Transport and Range of Ions in Matter, Sputtering version (TRIM.SP) code [J.P. Biersack, W. Eckstein, Appl. Phys. A: Mater. Sci. Process. 34 (1984) 73]. The thicknesses of the films are in good agreement with those calculated from simulated particle fluxes. For the positions of the
Internal Energy Distribution in Sympathetically Cooled Molecular Ions
NASA Astrophysics Data System (ADS)
Thompson, Robert I.; Fisher, Amy; Harmon, Thomas; Winslade, Clayton; Ahmadi, Nasser
2002-05-01
Over the past year a research program at the University of Calgary has begun looking at the distribution of energy in the internal degrees of freedom (vibrational and rotational) of trapped and sympathetically cooled molecular ions. Ion traps are capable of holding mixed samples of charged atoms and molecules simultaneously. Atomic ions in the trapped cloud can be laser cooled by traditional techniques. The molecular ions are not directly laser cooled, but all of the trapped particles are charged so they interact strongly through Coulomb forces. It has been experimentally demonstrated that the external or translational degrees of freedom of the non-laser-cooled species are significantly lowered through this interaction (e.g. [1]). However, there is little known about the energy distribution in the in the internal degrees of freedom. This poster will outline the results of our theoretical work, as well as the technical design, construction, and initial work in the laboratory. [1] T. Baba and I. Waki, Jpn. J. Appl. Phys. 35, L1134 (1996).
Wang, Y. Y.; Grygiel, C.; Dufour, C.; Sun, J. R.; Wang, Z. G.; Zhao, Y. T.; Xiao, G. Q.; Cheng, R.; Zhou, X. M.; Ren, J. R.; Liu, S. D.; Lei, Y.; Sun, Y. B.; Ritter, R.; Gruber, E.; Cassimi, A.; Monnet, I.; Bouffard, S.; Aumayr, F.; Toulemonde, M.
2014-01-01
Modification of surface and bulk properties of solids by irradiation with ion beams is a widely used technique with many applications in material science. In this study, we show that nano-hillocks on CaF2 crystal surfaces can be formed by individual impact of medium energy (3 and 5 MeV) highly charged ions (Xe22+ to Xe30+) as well as swift (kinetic energies between 12 and 58 MeV) heavy xenon ions. For very slow highly charged ions the appearance of hillocks is known to be linked to a threshold in potential energy (Ep) while for swift heavy ions a minimum electronic energy loss per unit length (Se) is necessary. With our results we bridge the gap between these two extreme cases and demonstrate, that with increasing energy deposition via Se the Ep-threshold for hillock production can be lowered substantially. Surprisingly, both mechanisms of energy deposition in the target surface seem to contribute in an additive way, which can be visualized in a phase diagram. We show that the inelastic thermal spike model, originally developed to describe such material modifications for swift heavy ions, can be extended to the case where both kinetic and potential energies are deposited into the surface. PMID:25034006
Wang, Y Y; Grygiel, C; Dufour, C; Sun, J R; Wang, Z G; Zhao, Y T; Xiao, G Q; Cheng, R; Zhou, X M; Ren, J R; Liu, S D; Lei, Y; Sun, Y B; Ritter, R; Gruber, E; Cassimi, A; Monnet, I; Bouffard, S; Aumayr, F; Toulemonde, M
2014-07-18
Modification of surface and bulk properties of solids by irradiation with ion beams is a widely used technique with many applications in material science. In this study, we show that nano-hillocks on CaF2 crystal surfaces can be formed by individual impact of medium energy (3 and 5 MeV) highly charged ions (Xe(22+) to Xe(30+)) as well as swift (kinetic energies between 12 and 58 MeV) heavy xenon ions. For very slow highly charged ions the appearance of hillocks is known to be linked to a threshold in potential energy (Ep) while for swift heavy ions a minimum electronic energy loss per unit length (Se) is necessary. With our results we bridge the gap between these two extreme cases and demonstrate, that with increasing energy deposition via Se the Ep-threshold for hillock production can be lowered substantially. Surprisingly, both mechanisms of energy deposition in the target surface seem to contribute in an additive way, which can be visualized in a phase diagram. We show that the inelastic thermal spike model, originally developed to describe such material modifications for swift heavy ions, can be extended to the case where both kinetic and potential energies are deposited into the surface.
Temporal Evolution of Ion Spectral Structures During a Geomagnetic Storm: Observations and Modeling
NASA Astrophysics Data System (ADS)
Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.
2018-01-01
Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1 to 50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convection electric field. Prior to the beginning of the storm, the plasma sheet inner edge exhibits narrow nose spectral structures that vary little in energy across
Low-energy particle experiments-ion mass analyzer (LEPi) onboard the ERG (Arase) satellite
NASA Astrophysics Data System (ADS)
Asamura, K.; Kazama, Y.; Yokota, S.; Kasahara, S.; Miyoshi, Y.
2018-05-01
Low-energy ion experiments-ion mass analyzer (LEPi) is one of the particle instruments onboard the ERG satellite. LEPi is an ion energy-mass spectrometer which covers the range of particle energies from < 0.01 to 25 keV/q. Species of incoming ions are discriminated by a combination of electrostatic energy-per-charge analysis and the time-of-flight technique. The sensor has a planar field-of-view, which provides 4π steradian coverage by using the spin motion of the satellite. LEPi started its nominal observation after the initial checkout and commissioning phase in space. [Figure not available: see fulltext.
Limandri, Silvina; de Vera, Pablo; Fadanelli, Raul C; Nagamine, Luiz C C M; Mello, Alexandre; Garcia-Molina, Rafael; Behar, Moni; Abril, Isabel
2014-02-01
Ion-beam cancer therapy is a promising technique to treat deep-seated tumors; however, for an accurate treatment planning, the energy deposition by the ions must be well known both in soft and hard human tissues. Although the energy loss of ions in water and other organic and biological materials is fairly well known, scarce information is available for the hard tissues (i.e., bone), for which the current stopping power information relies on the application of simple additivity rules to atomic data. Especially, more knowledge is needed for the main constituent of human bone, calcium hydroxyapatite (HAp), which constitutes 58% of its mass composition. In this work the energy loss of H and He ion beams in HAp films has been obtained experimentally. The experiments have been performed using the Rutherford backscattering technique in an energy range of 450-2000 keV for H and 400-5000 keV for He ions. These measurements are used as a benchmark for theoretical calculations (stopping power and mean excitation energy) based on the dielectric formalism together with the MELF-GOS (Mermin energy loss function-generalized oscillator strength) method to describe the electronic excitation spectrum of HAp. The stopping power calculations are in good agreement with the experiments. Even though these experimental data are obtained for low projectile energies compared with the ones used in hadron therapy, they validate the mean excitation energy obtained theoretically, which is the fundamental quantity to accurately assess energy deposition and depth-dose curves of ion beams at clinically relevant high energies. The effect of the mean excitation energy choice on the depth-dose profile is discussed on the basis of detailed simulations. Finally, implications of the present work on the energy loss of charged particles in human cortical bone are remarked.
NASA Astrophysics Data System (ADS)
Snowden, Darci; Smith, Michael; Jimson, Theodore; Higgins, Alex
2018-05-01
Cassini's Radio Science Investigation (RSS) and Langmuir Probe observed abnormally high electron densities in Titan's ionosphere during Cassini's T57 flyby. We have developed a three-dimensional model to investigate how the precipitation of thermal magnetospheric O+ may have contributed to enhanced ion production in Titan's ionosphere. The three-dimensional model builds on previous work because it calculates both the flux of oxygen through Titan's exobase and the energy deposition and ion production rates in Titan's atmosphere. We find that energy deposition rates and ion production rates due to thermal O+ precipitation have a similar magnitude to the rates from magnetospheric electron precipitation and that the simulated ionization rates are sufficient to explain the abnormally high electron densities observed by RSS and Cassini's Langmuir Probe. Globally, thermal O+ deposits less energy in Titan's atmosphere than solar EUV, suggesting it has a smaller impact on the thermal structure of Titan's neutral atmosphere. However, our results indicate that thermal O+ precipitation can have a significant impact on Titan's ionosphere.
CERA-V: Microwave plasma stream source with variable ion energy
DOE Office of Scientific and Technical Information (OSTI.GOV)
Balmashnov, A.A.
1996-01-01
A microwave plasma stream source with variable ion energy operated under low magnetic field electron cyclotron resonance conditions has been developed. A two mode resonant cavity (TE{sub 111}, {ital E}{sub 010}) was used. It was established that overdense plasma creation (TE{sub 111}) and high energy in-phase space localized electron plasma oscillations ({ital E}{sub 010}) in a decreased magnetic field lead to the potential for ion energy variation from 10 to 300 eV (up to 1 A of ion current, and a plasma cross section of 75 cm{sup 2}, hydrogen) by varying the TE{sub 111}, {ital E}{sub 010} power, the valuemore » of the magnetic field, and pressure. The threshold level of {ital E}{sub 010}-mode power was also determined. An application of this CERA-V source to hydrogenation of semiconductor devices without deterioration of surface layers by ions and fast atoms is under investigation. {copyright} {ital 1996 American Vacuum Society}« less
Ion composition and energy distribution during 10 magnetic storms
NASA Technical Reports Server (NTRS)
Lennartsson, W.; Sharp, R. D.; Shelley, E. G.; Johnson, R. G.; Balsiger, H.
1981-01-01
Data from the plasma composition experiment of ISEE 1 are used to investigate the relative quantities and energy characteristics of H(+), He(++), He(+), and O(+) ions in the near-equatorial magnetosphere during magnetic storm conditions. The ions in the study had energies between 0.1 and 17 keV/e and pitch angles between 45 and 135 deg. The data were obtained during 10 storms, for the most part at or immediately following the peak Dst, covering all major local time sectors and geocentric distances between 2 and 15 earth radii. The ion fluxes are averaged over the spacecraft spin angle and over time for periods ranging from about 20 min close to the earth to more than an hour in most distant regions. The inferred 'isotropic' number densities are characterized by a large to dominant fraction of terrestrial ions throughout the energy range covered. The data are found to be consistent with a terrestrial origin for all of the O(+), most of the He(+), and a large but varying fraction of the H(+), whereas the He(++) and part of the H(+) appear to be of solar wind origin.
A search for energetic ion directivity in large solar flares
NASA Astrophysics Data System (ADS)
Vestrand, W. Thomas
One of the key observational questions for solar flare physics is: What is the number, the energy spectrum, and the angular distribution of flare accelerated ions? The standard method for deriving ion spectral shape employs the ratio of influences observed on the 4-7 MeV band to the narrow neutron capture line at 2.223 MeV. The 4-7 MeV band is dominated by the principal nuclear de-excitation lines from C-12 and O-16 which are generated in the low chromosphere by the direct excitation or spallation of nuclei by energetic ions. In contrast, the narrow 2.223 MeV line is produced by the capture of thermal neutrons on protons in the photosphere. These capture neutrons are generated by energetic ion interactions and thermalized by scattering in the solar atmosphere. In a series of papers, Ramaty, Lingenfelter, and their collaborators have calculated the expected ratio of fluence in the 4-7 MeV band to the 2.223 MeV line for a wide range of energetic ion spectral shapes (see, e.g. Hua and Lingenfelter 1987). Another technique for deriving ion spectral shapes and angular distributions uses the relative strength of the Compton tail associated with the 2.223 MeV neutron capture line (Vestrand 1988, 1990). This technique can independently constrain both the angular and the energy distribution of the energetic parent ions. The combination of this tail/line strength diagnostic with the line/(4-7) MeV fluence ratio can allow one to constrain both properties of the energetic ion distributions. The primary objective of our Solar Maximum Mission (SMM) guest investigator program was to study measurements of neutron capture line emission and prompt nuclear de-excitation for large flares detected by the Solar Maximum Mission/ Gamma-Ray Spectrometer (SMM/GRS) and to use these established line diagnostics to study the properties of flare accelerated ions.
Neutral beamline with ion energy recovery based on magnetic blocking of electrons
Stirling, W.L.
1980-07-01
A neutral beamline generator with energy recovery of the full-energy ion component of the beam based on magnetic blocking of electrons is provided. Ions from a positive ion source are accelerated to the desired beam energy from a slightly positive potential level with respect to ground through a neutralizer cell by means of a negative acceleration voltage. The unneutralized full-energy ion component of the beam exiting the neutralizer are retarded and slightly deflected and the elecrons in the neutralizer are blocked by a magnetic field generated transverse to the beamline. An electron collector in the form of a coaxial cylinder surrounding and protruding axial a few centimeters beyond the neutralizer exit terminates the electrons which exit the neutralizer in an E x B drift to the collector when the collector is biased a few hundred volts positive with respect to the neutralizer voltage. The neutralizer is operated at the negative acceleration voltage. The neutralizer is operated at the negative acceleration voltage, and the deflected full energy ions are decelerated and the charge collected at ground potential thereby expending none of their energy received from the acceleration power supply.
Two-stage energy storage equalization system for lithium-ion battery pack
NASA Astrophysics Data System (ADS)
Chen, W.; Yang, Z. X.; Dong, G. Q.; Li, Y. B.; He, Q. Y.
2017-11-01
How to raise the efficiency of energy storage and maximize storage capacity is a core problem in current energy storage management. For that, two-stage energy storage equalization system which contains two-stage equalization topology and control strategy based on a symmetric multi-winding transformer and DC-DC (direct current-direct current) converter is proposed with bidirectional active equalization theory, in order to realize the objectives of consistent lithium-ion battery packs voltages and cells voltages inside packs by using a method of the Range. Modeling analysis demonstrates that the voltage dispersion of lithium-ion battery packs and cells inside packs can be kept within 2 percent during charging and discharging. Equalization time was 0.5 ms, which shortened equalization time of 33.3 percent compared with DC-DC converter. Therefore, the proposed two-stage lithium-ion battery equalization system can achieve maximum storage capacity between lithium-ion battery packs and cells inside packs, meanwhile efficiency of energy storage is significantly improved.
Realizing synchronous energy harvesting and ion separation with graphene oxide membranes.
Sun, Pengzhan; Zheng, Feng; Zhu, Miao; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei
2014-07-02
A synchronous ion separation and electricity generation process has been developed using G-O membranes. In addition to the size effect proposed prevsiouly, the separation of ions can be attributed to the different interactions between ions and G-O membranes; the generation of electricity is due to the confinement of G-O membranes, and the mobility difference of ions. Efficient energy transduction has been achieved with G-O membranes, converting magnetic, thermal and osmotic energy to electricity, distinguishing this material from other commercial semi-permeable membranes. Our study indicated that G-O membranes could find potential applications in the purification of wastewater, while producing electricity simultaneously. With G-O membranes, industrial magnetic leakage and waste heat could also be used to produce electricity, affording a superior approach for energy recovery.
Characteristics of low energy ions in the Heavy Ions In Space (HIIS) experiment
NASA Technical Reports Server (NTRS)
Kleis, Thomas; Tylka, Allan J.; Boberg, Paul R.; Adams, James H., Jr.; Beahm, Lorraine P.
1995-01-01
We present preliminary data on heavy ions (Z greater than or equal to 10) detected in the topmost Lexan sheets of the track detector stacks of the Heavy Ions in space (HIIS) experiment (M0001) on LDEF. The energy interval covered by these observations varies with the element, with (for example) Ne observable at 18-100 MeV nuc and Fe at 45-200 MeV/nuc. All of the observed ions are at energies far below the geomagnetic cutoff for fully-ionized particles at the LDEF orbit. Above 50 MeV/nuc (where most of our observed particles are Fe), the ions arrive primarily from the direction of lowest geomagnetic cutoff. This suggests that these particles originate outside the magnetosphere from a source with a steeply-falling spectrum and may therefore be associated with solar energetic particle (SEP) events. Below 50 MeV/nuc, the distribution of arrival directions suggests that most of the observed heavy ions are trapped in the Earth's magnetic field. Preliminary analysis, however, shows that these trapped heavy ions have a very surprising composition: they include not only Ne and Ar, which are expected from the trapping of anomalous cosmic rays (ACR's), but also Mg and Si, which are not part of the anomalous component. Our preliminary analysis shows that trapped heavy ions at 12 less than or equal to Zeta less than or equal to 14 have a steeply-falling spectrum, similar to that reported by the Kiel experiment (exp 1,2,3) on LDEF (M0002) for trapped Ar and Fe at E less than 50 MeV/nuc. The trapped Mg, Si, and Fe may also be associated with SEP events, but the mechanism by which they have appeared to deep in the inner magnetosphere requires further theoretical investigation.
NASA Astrophysics Data System (ADS)
Niranjan, Ram; Rout, R. K.; Srivastava, Rohit; Kaushik, T. C.
2018-03-01
The effects of gas filling pressure and operation energy on deuterium ions and neutrons have been studied in a medium energy plasma focus device, MEPF-12. The deuterium gas filling pressure was varied from 1 to 10 mbar at an operation energy of 9.7 kJ. Also, the operation energy was varied from 3.9 to 9.7 kJ at a deuterium gas filling pressure of 4 mbar. Time resolved emission of deuterium ions was measured using a Faraday cup. Simultaneously, time integrated and time resolved emissions of neutrons were measured using a silver activation detector and plastic scintillator detector, respectively. Various characteristics (fluence, peak density, and most probable energy) of deuterium ions were estimated using the Faraday cup signal. The fluence was found to be nearly independent of the gas filling pressure and operation energy, but the peak density and most probable energy of deuterium ions were found to be varying. The neutron yield was observed to be varying with the gas filling pressure and operation energy. The effect of ions on neutrons emission was observed at each operation condition.
NASA Astrophysics Data System (ADS)
Chowdhury, D. P.; Guin, R.; Saha, S. K.; Sudersanan, M.
2003-11-01
Experimental cross sections of a number of reaction channels of 16O ion induced reactions on natural copper target have been determined at different energies in the range of 50-110 MeV of 16O projectile by stacked foil activation technique. The cross sections have been compared with theoretical calculations using the computer code ALICE-91. The experimental values compared reasonably well with the corresponding theoretical estimates. The results indicate no significant role of incomplete fusion process in the 16O induced reactions on natural copper in the energy range of ⩽7 MeV/nucleon. As heavy ion beam produces an extremely narrow layer of activities in the surface of a material, these reactions could be useful for thin layer activation (TLA) study. The purpose of this work is to apply heavy ion activation in TLA technique for the study of surface wear with increased sensitivity.
Keeping the Edges Sharp I: Honing the Theory of Narrow Rings
NASA Astrophysics Data System (ADS)
Hamilton, Douglas P.; Rimlinger, Thomas; Hahn, Joseph M.
2016-05-01
Most of the rings that encircle Saturn, Uranus, and Neptune are very narrow structures with typical radial widths of just a few kilometers. Such extreme sharpness is surprising, as even slightly different orbital periods should allow ring particles to continually jostle one another in collisions that preserve angular momentum whileinexorably draining energy. Sharp edges should blur as rings spread in response to collisions and yet they do not. The generally accepted solution to this dilemma is to bracket each narrow ring with a pair of shepherding satellites that can pump energy back into the ring to replace that lost by collisions. But only a disappointing two of roughly twenty narrow rings actually have known attendant satellites. We present a compelling alternative in which the slight eccentricities and inclinations of narrow ringlets act as internal energy sources that can be tapped to prevent ring spreading. When unattended circular rings dissipate energy they must spread radially in order to preserve angular momentum. By contrast, eccentric or inclined rings have an extra degree of freedom that can be exploited to prevent radial spreading; energy is dissipated while keeping z-component of angular momentum, sqrt(a(1-e^2))cos(i), constant by simply decreasing the overall eccentricity (e) and/or inclination (i) of the entire ring. A real narrow ring moves inward as a unit, circularizes, and drops into the equatorial plane in a process that deters radial spreading for millions or billions of years. Using secular theory with dissipation (Zhang et al. 2013), we show that narrow rings are secular eigenstates in which ellipses are nested with pericenters almost, but not exactly aligned. The misalignment of pericenters is crucial in allowing energy dissipation to be shared evenly across the ring. We predict ring surface densities that are roughly constant across the ring's width, in contrast to profiles expected for shepherded rings. Rimlinger et al. (this meeting
Low-energy ion beam-based deposition of gallium nitride
DOE Office of Scientific and Technical Information (OSTI.GOV)
Vasquez, M. R., E-mail: mrvasquez@coe.upd.edu.ph; Wada, M.
2016-02-15
An ion source with a remote plasma chamber excited by a 13.56 MHz radio frequency power was used for low-energy broad ion beam extraction. Optical emission spectral analyses showed the sputtering and postionization of a liquid gallium (Ga) target placed in a chamber separated from the source bombarded by argon (Ar) plasma guided by a bent magnetic field. In addition, an E × B probe successfully showed the extraction of low-energy Ga and Ar ion beams using a dual-electrode extractor configuration. By introducing dilute amounts of nitrogen gas into the system, formation of thin Ga-based films on a silicon substratemore » was demonstrated as determined from X-ray diffraction and X-ray reflectivity studies.« less
Note: A well-confined pulsed low-energy ion beam: Test experiments of Ar+
NASA Astrophysics Data System (ADS)
Hu, Jie; Wu, Chun-Xiao; Tian, Shan Xi
2018-06-01
Here we report a pulsed low-energy ion beam source for ion-molecule reaction study, in which the ions produced by the pulsed electron impact are confined well in the spatial size of each bunch. In contrast to the ion focusing method to reduce the transverse section of the beam, the longitudinal section in the translational direction is compressed by introducing a second pulse in the ion time-of-flight system. The test experiments for the low-energy argon ions are performed. The present beam source is ready for applications in the ion-molecule reaction dynamics experiments, in particular, in combination with the ion velocity map imaging technique.
Evaluation of laser-driven ion energies for fusion fast-ignition research
NASA Astrophysics Data System (ADS)
Tosaki, S.; Yogo, A.; Koga, K.; Okamoto, K.; Shokita, S.; Morace, A.; Arikawa, Y.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H.; Nishimura, H.
2017-10-01
We investigate laser-driven ion acceleration using kJ-class picosecond (ps) laser pulses as a fundamental study for ion-assisted fusion fast ignition, using a newly developed Thomson-parabola ion spectrometer (TPIS). The TPIS has a space- and weight-saving design, considering its use in an laser-irradiation chamber in which 12 beams of fuel implosion laser are incident, and, at the same time, demonstrates sufficient performance with its detectable range and resolution of the ion energy required for fast-ignition research. As a fundamental study on laser-ion acceleration using a ps pulse laser, we show proton acceleration up to 40 MeV at 1 × 10^{19} W cm^{-2}. The energy conversion efficiency from the incident laser into protons higher than 6 MeV is 4.6%, which encourages the realization of fusion fast ignition by laser-driven ions.
Real single ion solvation free energies with quantum mechanical simulation
Duignan, Timothy T.; Baer, Marcel D.; Schenter, Gregory K.; ...
2017-07-04
Single ion solvation free energies are one of the most important properties of electrolyte solutions and yet there is ongoing debate about what these values are. Only the values for neutral ion pairs are known. Here, we use DFT interaction potentials with molecular dynamics simulation (DFT-MD) combined with a modified version of the quasi-chemical theory (QCT) to calculate these energies for the lithium and fluoride ions. A method to correct for the error in the DFT functional is developed and very good agreement with the experimental value for the lithium fluoride pair is obtained. Moreover, this method partitions the energiesmore » into physically intuitive terms such as surface potential, cavity and charging energies which are amenable to descriptions with reduced models. Here, our research suggests that lithium's solvation free energy is dominated by the free energetics of a charged hard sphere, whereas fluoride exhibits significant quantum mechanical behavior that cannot be simply described with a reduced model.« less
Real single ion solvation free energies with quantum mechanical simulation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Duignan, Timothy T.; Baer, Marcel D.; Schenter, Gregory K.
Single ion solvation free energies are one of the most important properties of electrolyte solutions and yet there is ongoing debate about what these values are. Only the values for neutral ion pairs are known. Here, we use DFT interaction potentials with molecular dynamics simulation (DFT-MD) combined with a modified version of the quasi-chemical theory (QCT) to calculate these energies for the lithium and fluoride ions. A method to correct for the error in the DFT functional is developed and very good agreement with the experimental value for the lithium fluoride pair is obtained. Moreover, this method partitions the energiesmore » into physically intuitive terms such as surface potential, cavity and charging energies which are amenable to descriptions with reduced models. Here, our research suggests that lithium's solvation free energy is dominated by the free energetics of a charged hard sphere, whereas fluoride exhibits significant quantum mechanical behavior that cannot be simply described with a reduced model.« less
Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel
DOE Office of Scientific and Technical Information (OSTI.GOV)
Fritsch, Sebastian M; Ivanov, Ivaylo N; Wang, Hailong
2011-01-01
The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor (nAChR) that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential of mean force (PMF) profiles for sodium and chloride ions inside the transmembrane region. Our calculationsmore » reveal that the GLIC channel is open for a sodium ion to transport, but presents a ~10 kcal/mol free energy barrier for a chloride ion, which arises primarily from the unfavorable interactions with a ring of negatively charged glutamate residues (E-2 ) at the intracellular end and a ring of hydrophobic residues (I9 ) in the middle of the transmembrane domain. Our collective findings further suggest that the charge selection mechanism can, to a large extent, be attributed to the narrow intracellular end and a ring of glutamate residues in this position their strong negative electrostatics and ability to bind cations. By contrast, E19 at the extracellular entrance only plays a minor role in ion selectivity of GLIC. In addition to electrostatics, both ion hydration and protein dynamics are found to be crucial for ion conduction as well, which explains why a chloride ion experiences a much greater barrier than a sodium ion in the hydrophobic region of the pore.« less
Selectivity and permeation of alkali metal ions in K+-channels.
Furini, Simone; Domene, Carmen
2011-06-24
Ion conduction in K(+)-channels is usually described in terms of concerted movements of K(+) progressing in a single file through a narrow pore. Permeation is driven by an incoming ion knocking on those ions already inside the protein. A fine-tuned balance between high-affinity binding and electrostatic repulsive forces between permeant ions is needed to achieve efficient conduction. While K(+)-channels are known to be highly selective for K(+) over Na(+), some K(+) channels conduct Na(+) in the absence of K(+). Other ions are known to permeate K(+)-channels with a more moderate preference and unusual conduction features. We describe an extensive computational study on ion conduction in K(+)-channels rendering free energy profiles for the translocation of three different alkali ions and some of their mixtures. The free energy maps for Rb(+) translocation show at atomic level why experimental Rb(+) conductance is slightly lower than that of K(+). In contrast to K(+) or Rb(+), external Na(+) block K(+) currents, and the sites where Na(+) transport is hindered are characterized. Translocation of K(+)/Na(+) mixtures is energetically unfavorable owing to the absence of equally spaced ion-binding sites for Na(+), excluding Na(+) from a channel already loaded with K(+). Copyright © 2011 Elsevier Ltd. All rights reserved.
Ultrathin and Ion-Selective Janus Membranes for High-Performance Osmotic Energy Conversion.
Zhang, Zhen; Sui, Xin; Li, Pei; Xie, Ganhua; Kong, Xiang-Yu; Xiao, Kai; Gao, Longcheng; Wen, Liping; Jiang, Lei
2017-07-05
The osmotic energy existing in fluids is recognized as a promising "blue" energy source that can help solve the global issues of energy shortage and environmental pollution. Recently, nanofluidic channels have shown great potential for capturing this worldwide energy because of their novel transport properties contributed by nanoconfinement. However, with respect to membrane-scale porous systems, high resistance and undesirable ion selectivity remain bottlenecks, impeding their applications. The development of thinner, low-resistance membranes, meanwhile promoting their ion selectivity, is a necessity. Here, we engineered ultrathin and ion-selective Janus membranes prepared via the phase separation of two block copolymers, which enable osmotic energy conversion with power densities of approximately 2.04 W/m 2 by mixing natural seawater and river water. Both experiments and continuum simulation help us to understand the mechanism for how membrane thickness and channel structure dominate the ion transport process and overall device performance, which can serve as a general guiding principle for the future design of nanochannel membranes for high-energy concentration cells.
NASA Astrophysics Data System (ADS)
Hannesdottir, H.; Gudmundsson, J. T.
2017-05-01
We apply particle-in-cell simulations with Monte Carlo collisions to study the influence of the singlet metastable states on the ion energy distribution in single and dual frequency capacitively coupled oxygen discharges. For this purpose, the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is used, in which the discharge model includes the following nine species: electrons, the neutrals O(3P) and O{{}2}≤ft({{\\text{X}}3} Σ g-\\right. ), the negative ions O-, the positive ions O+ and O2+ , and the metastables O(1D), O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right) and O2(b{{}1} Σ g+ ). Earlier, we have explored the effects of adding the species O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ), and an energy-dependent secondary electron emission yield for oxygen ions and neutrals, to the discharge model. We found that including the two molecular singlet metastable states decreases the ohmic heating and the effective electron temperature in the bulk region (the electronegative core). Here we explore how these metastable states influence dual frequency discharges consisting of a fundamental frequency and the lowest even harmonics. Including or excluding the detachment reactions of the metastables O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ) can shift the peak electron temperature from the grounded to the powered electrode or vice versa, depending on the phase difference of the two applied frequencies. These metastable states can furthermore significantly influence the peak of the ion energy distribution for O2+ -ions bombarding the powered electrode, and hence the average ion energy upon bombardment of the electrode, and lower the ion flux.
RF System Requirements for a Medium-Energy Electron-Ion Collider (MEIC) at JLab
DOE Office of Scientific and Technical Information (OSTI.GOV)
Rimmer, Robert A; Hannon, Fay E; Guo, Jiquan
2015-09-01
JLab is studying options for a medium energy electron-ion collider that could fit on the JLab site and use CEBAF as a full-energy electron injector. A new ion source, linac and booster would be required, together with collider storage rings for the ions and electrons. In order to achieve the maximum luminosity these will be high-current storage rings with many bunches. We present the high-level RF system requirements for the storage rings, ion booster ring and high-energy ion beam cooling system, and describe the technology options under consideration to meet them. We also present options for staging that might reducemore » the initial capital cost while providing a smooth upgrade path to a higher final energy. The technologies under consideration may also be useful for other proposed storage ring colliders or ultimate light sources.« less
A Hierarchy of Transport Approximations for High Energy Heavy (HZE) Ions
NASA Technical Reports Server (NTRS)
Wilson, John W.; Lamkin, Stanley L.; Hamidullah, Farhat; Ganapol, Barry D.; Townsend, Lawrence W.
1989-01-01
The transport of high energy heavy (HZE) ions through bulk materials is studied neglecting energy dependence of the nuclear cross sections. A three term perturbation expansion appears to be adequate for most practical applications for which penetration depths are less than 30 g per sq cm of material. The differential energy flux is found for monoenergetic beams and for realistic ion beam spectral distributions. An approximate formalism is given to estimate higher-order terms.
Zhao, H.; Li, X.; Baker, D. N.; ...
2015-08-25
Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute moremore » significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O +. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhao, H.; Li, X.; Baker, D. N.
Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute moremore » significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O +. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bodin, A.; Laloo, R.; Abeilhou, P.
2013-09-15
We have developed an energy-filtering device coupled to a quadrupole mass spectrometer to deposit ionized molecules on surfaces with controlled energy in ultra high vacuum environment. Extensive numerical simulations as well as direct measurements show that the ion beam flying out of a quadrupole exhibits a high-energy tail decreasing slowly up to several hundred eV. This energy distribution renders impossible any direct soft-landing deposition of molecular ions. To remove this high-energy tail by energy filtering, a 127° electrostatic sector and a specific triplet lenses were designed and added after the last quadrupole of a triple quadrupole mass spectrometer. The resultsmore » obtained with this energy-filtering device show clearly the elimination of the high-energy tail. The ion beam that impinges on the sample surface satisfies now the soft-landing criterion for molecular ions, opening new research opportunities in the numerous scientific domains involving charges adsorbed on insulating surfaces.« less
Generation of monoenergetic ion beams via ionization dynamics (Conference Presentation)
NASA Astrophysics Data System (ADS)
Lin, Chen; Kim, I. Jong; Yu, Jinqing; Choi, Il Woo; Ma, Wenjun; Yan, Xueqing; Nam, Chang Hee
2017-05-01
The research on ion acceleration driven by high intensity laser pulse has attracted significant interests in recent decades due to the developments of laser technology. The intensive study of energetic ion bunches is particularly stimulated by wide applications in nuclear fusion, medical treatment, warm dense matter production and high energy density physics. However, to implement such compact accelerators, challenges are still existing in terms of beam quality and stability, especially in applications that require higher energy and narrow bandwidth spectra ion beams. We report on the acceleration of quasi-mono-energetic ion beams via ionization dynamics in the interaction of an intense laser pulse with a solid target. Using ionization dynamics model in 2D particle-in-cell (PIC) simulations, we found that high charge state contamination ions can only be ionized in the central spot area where the intensity of sheath field surpasses their ionization threshold. These ions automatically form a microstructure target with a width of few micron scale, which is conducive to generate mono-energetic beams. In the experiment of ultraintense (< 10^21 W/cm^2) laser pulses irradiating ultrathin targets each attracted with a contamination layer of nm-thickness, high quality < 100 MeV mono-energetic ion bunches are generated. The peak energy of the self-generated micro-structured target ions with respect to different contamination layer thickness is also examined This is relatively newfound respect, which is confirmed by the consistence between experiment data and the simulation results.
Low energy ion beam induced changes in ETFE polymer
NASA Astrophysics Data System (ADS)
Parada, M. A.; Delalez, N.; de Almeida, A.; Muntele, C.; Muntele, I.; Ila, D.
2006-01-01
Low energy ion beam bombardment of ethylenetetrafluoroethylene (ETFE) modifies the physical and chemical properties of the polymer surface in ways that enhance or compromise applications in the technological and medical physics fields. When a material is exposed to ionizing radiation, its changes depends on the type, energy and intensity of the applied radiation. In order to determine the nature of the induced radiation changes, ETFE films were bombarded with fluences from 1012 up to 1015 ions/cm2 of keV N and protons. The emission of gaseous species during the bombardments was monitored with a residual gas analyser (RGA). The bombarded films were analysed with optical absorption photospectrometry (OAP), Fourier transform infrared (FTIR) and micro-Raman spectrometries that determine the chemical nature of the structural changes caused by ions bombardment.
NASA Astrophysics Data System (ADS)
Fernández, Juan C.; Palaniyappan, S.; Huang, C.; Gautier, D. C.; Santiago, M.
2015-11-01
Using massive computer simulations of relativistic laser-plasma interactions, we have identified a self-organizing scheme that exploits persisting self-generated plasma electric (~TV/m) and magnetic (~104 Tesla) fields to reduce the ion energy spread of intense laser-driven ion beams after the laser exits the plasma. Consistent with the scheme, we have demonstrated on the LANL Trident laser carbon-ion beams with narrow spectral peaks at 220 MeV, with high conversion efficiency (~ 5%). These parameters are within a factor of 2 of FI requirements. The remaining gap may be bridged by increasing the laser intensity by a factor of 4, according to our data. We also discuss how this beam may be focused, to address the remaining requirement for FI, besides the total laser energy. This work is sponsored by the LANL LDRD Program.
Temporal evolution of ion spectral structures during a geomagnetic storm: Observations and modeling
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ferradas Alva, Cristian Pablo; Zhang, J.-C.; Spence, H. E.
Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron (HOPE) mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1- ~50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convection electric field. Prior to the beginning of the storm, the plasma sheet innermore » edge exhibits narrow nose spectral structures that vary little in energy across L values. Ion access to the inner magnetosphere during these times is limited to the nose energy bands. As convection is enhanced and large amounts of plasma are injected from the plasma sheet during the main phase of the storm, ion access occurs at a wide energy range, as no nose structures are observed. Here, as the magnetosphere recovers from the storm, single noses and then multiple noses are observed once again. Lastly, we use a model of ion drift and losses due to charge exchange to simulate the ion spectra and gain insight into the main observed features.« less
Temporal evolution of ion spectral structures during a geomagnetic storm: Observations and modeling
Ferradas Alva, Cristian Pablo; Zhang, J.-C.; Spence, H. E.; ...
2017-12-13
Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron (HOPE) mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1- ~50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convection electric field. Prior to the beginning of the storm, the plasma sheet innermore » edge exhibits narrow nose spectral structures that vary little in energy across L values. Ion access to the inner magnetosphere during these times is limited to the nose energy bands. As convection is enhanced and large amounts of plasma are injected from the plasma sheet during the main phase of the storm, ion access occurs at a wide energy range, as no nose structures are observed. Here, as the magnetosphere recovers from the storm, single noses and then multiple noses are observed once again. Lastly, we use a model of ion drift and losses due to charge exchange to simulate the ion spectra and gain insight into the main observed features.« less
Sn ion energy distributions of ns- and ps-laser produced plasmas
NASA Astrophysics Data System (ADS)
Bayerle, A.; Deuzeman, M. J.; van der Heijden, S.; Kurilovich, D.; de Faria Pinto, T.; Stodolna, A.; Witte, S.; Eikema, K. S. E.; Ubachs, W.; Hoekstra, R.; Versolato, O. O.
2018-04-01
Ion energy distributions arising from laser-produced plasmas of Sn are measured over a wide laser parameter space. Planar-solid and liquid-droplet targets are exposed to infrared laser pulses with energy densities between 1 J cm‑2 and 4 kJ cm‑2 and durations spanning 0.5 ps to 6 ns. The measured ion energy distributions are compared to two self-similar solutions of a hydrodynamic approach assuming isothermal expansion of the plasma plume into vacuum. For planar and droplet targets exposed to ps-long pulses, we find good agreement between the experimental results and the self-similar solution of a semi-infinite simple planar plasma configuration with an exponential density profile. The ion energy distributions resulting from solid Sn exposed to ns-pulses agrees with solutions of a limited-mass model that assumes a Gaussian-shaped initial density profile.
The Marshall Space Flight Center Low-Energy Ion Facility: A preliminary report
NASA Technical Reports Server (NTRS)
Biddle, A. P.; Reynolds, J. W.; Chisholm, W. L., Jr.; Hunt, R. D.
1983-01-01
The Low-Energy Ion Facility (LEIF) is designed for laboratory research of low-energy ion beams similar to those present in the magnetosphere. In addition, it provides the ability to develop and calibrate low-energy, less than 50 eV, plasma instrumentation over its full range of energy, mass, flux, and arrival angle. The current status of this evolving resource is described. It also provides necessary information to allow users to utilize it most efficiently.
Tracking of Polycarbonate Films using Low-energy Ions Final Report CRADA No. TC-774-94
DOE Office of Scientific and Technical Information (OSTI.GOV)
Musket, R. G.
2018-01-24
Ion tracking is performed almost exclusively using ions with energies near or above the maximum in electronic stopping. For the present study, we have examined the results of etching ion tracks created by ions bombarding polycarbonate films with energies corresponding to stopping well below the maximum and just above the anticipated threshold for creating etchable latent tracks. Low-energy neon and argon ions with 18-60 keV /amu and fluences of about 10 8/cm 2 were used to examine the limits for producing etchable tracks in polycarbonate films. By concentrating on the early stages of etching (i.e., -20 nm < SEM holemore » diameter < -100 nm), we can directly relate the energy deposition calculated for the incident ion to the creation of etchable tracks. The experimental results will be discussed with regard to the energy losses of the ions in the polycarbonate films and to the formation of continuous latent tracks through the entire thickness the films. These results have significant implications with respect to the threshold for formation of etchable tracks and to the use of low-energy ions for lithographic applications.« less
Range and Energy Straggling in Ion Beam Transport
NASA Technical Reports Server (NTRS)
Wilson, John W.; Tai, Hsiang
2000-01-01
A first-order approximation to the range and energy straggling of ion beams is given as a normal distribution for which the standard deviation is estimated from the fluctuations in energy loss events. The standard deviation is calculated by assuming scattering from free electrons with a long range cutoff parameter that depends on the mean excitation energy of the medium. The present formalism is derived by extrapolating Payne's formalism to low energy by systematic energy scaling and to greater depths of penetration by a second-order perturbation. Limited comparisons are made with experimental data.
Magnetic Field Generation During the Collision of Narrow Plasma Clouds
NASA Astrophysics Data System (ADS)
Sakai, Jun-ichi; Kazimura, Yoshihiro; Haruki, Takayuki
1999-06-01
We investigate the dynamics of the collision of narrow plasma clouds,whose transverse dimension is on the order of the electron skin depth.A 2D3V (two dimensions in space and three dimensions in velocity space)particle-in-cell (PIC) collisionless relativistic code is used toshow the generation of a quasi-staticmagnetic field during the collision of narrow plasma clouds both inelectron-ion and electron-positron (pair) plasmas. The localizedstrong magnetic fluxes result in the generation of the charge separationwith complicated structures, which may be sources of electromagneticas well as Langmuir waves. We also present one applicationof this process, which occurs during coalescence of magnetic islandsin a current sheet of pair plasmas.
Sharpening of field emitter tips using high-energy ions
Musket, Ronald G.
1999-11-30
A process for sharpening arrays of field emitter tips of field emission cathodes, such as found in field-emission, flat-panel video displays. The process uses sputtering by high-energy (more than 30 keV) ions incident along or near the longitudinal axis of the field emitter to sharpen the emitter with a taper from the tip or top of the emitter down to the shank of the emitter. The process is particularly applicable to sharpening tips of emitters having cylindrical or similar (e.g., pyramidal) symmetry. The process will sharpen tips down to radii of less than 12 nm with an included angle of about 20 degrees. Because the ions are incident along or near the longitudinal axis of each emitter, the tips of gated arrays can be sharpened by high-energy ion beams rastered over the arrays using standard ion implantation equipment. While the process is particularly applicable for sharpening of arrays of field emitters in field-emission flat-panel displays, it can be effectively utilized in the fabrication of other vacuum microelectronic devices that rely on field emission of electrons.
Direct observation of a Γ -X energy spectrum transition in narrow AlAs quantum wells
NASA Astrophysics Data System (ADS)
Khisameeva, A. R.; Shchepetilnikov, A. V.; Muravev, V. M.; Gubarev, S. I.; Frolov, D. D.; Nefyodov, Yu. A.; Kukushkin, I. V.; Reichl, C.; Tiemann, L.; Dietsche, W.; Wegscheider, W.
2018-03-01
Spectra of magnetoplasma excitations have been investigated in two-dimensional electron systems in AlAs quantum wells (QWs) of different widths. The magnetoplasma spectrum has been found to change profoundly when the quantum well width becomes thinner than 5.5 nm, indicating a drastic change in the conduction electron energy spectrum. The transformation can be interpreted in terms of transition from the in-plane strongly anisotropic Xx-Xy valley occupation to the out-of-plane isotropic Xz valley in the QW plane. Strong enhancement of the cyclotron effective mass over the band value in narrow AlAs QWs is reported.
Sodium-ion hybrid electrolyte battery for sustainable energy storage applications
NASA Astrophysics Data System (ADS)
Senthilkumar, S. T.; Abirami, Mari; Kim, Junsoo; Go, Wooseok; Hwang, Soo Min; Kim, Youngsik
2017-02-01
Sustainable, safe, and low-cost energy storage systems are essential for large-scale electrical energy storage. Herein, we report a sodium (Na)-ion hybrid electrolyte battery with a replaceable cathode system, which is separated from the Na metal anode by a Na superionic conducting ceramic. By using a fast Na-ion-intercalating nickel hexacyanoferrate (NiHCF) cathode along with an eco-friendly seawater catholyte, we demonstrate good cycling performance with an average discharge voltage of 3.4 V and capacity retention >80% over 100 cycles and >60% over 200 cycle. Remarkably, such high capacity retention is observed for both the initial as well as replaced cathodes. Moreover, a Na-metal-free hybrid electrolyte battery containing hard carbon as the anode exhibits an energy density of ∼146 Wh kg-1 at a current density of 10 mA g-1, which is comparable to that of lead-acid batteries and much higher than that of conventional aqueous Na-ion batteries. These results pave the way for further advances in sustainable energy storage technology.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Abeyratne, S; Ahmed, S; Barber, D
2012-08-01
Researchers have envisioned an electron-ion collider with ion species up to heavy ions, high polarization of electrons and light ions, and a well-matched center-of-mass energy range as an ideal gluon microscope to explore new frontiers of nuclear science. In its most recent Long Range Plan, the Nuclear Science Advisory Committee (NSAC) of the US Department of Energy and the National Science Foundation endorsed such a collider in the form of a 'half-recommendation.' As a response to this science need, Jefferson Lab and its user community have been engaged in feasibility studies of a medium energy polarized electron-ion collider (MEIC), cost-effectivelymore » utilizing Jefferson Lab's already existing Continuous Electron Beam Accelerator Facility (CEBAF). In close collaboration, this community of nuclear physicists and accelerator scientists has rigorously explored the science case and design concept for this envisioned grand instrument of science. An electron-ion collider embodies the vision of reaching the next frontier in Quantum Chromodynamics - understanding the behavior of hadrons as complex bound states of quarks and gluons. Whereas the 12 GeV Upgrade of CEBAF will map the valence-quark components of the nucleon and nuclear wave functions in detail, an electron-ion collider will determine the largely unknown role sea quarks play and for the first time study the glue that binds all atomic nuclei. The MEIC will allow nuclear scientists to map the spin and spatial structure of quarks and gluons in nucleons, to discover the collective effects of gluons in nuclei, and to understand the emergence of hadrons from quarks and gluons. The proposed electron-ion collider at Jefferson Lab will collide a highly polarized electron beam originating from the CEBAF recirculating superconducting radiofrequency (SRF) linear accelerator (linac) with highly polarized light-ion beams or unpolarized light- to heavy-ion beams from a new ion accelerator and storage complex. Since the
Observations of low-energy ions in the wake of a magnetospheric satellite
NASA Technical Reports Server (NTRS)
Samir, U.; Comfort, R. H.; Chappell, C. R.; Stone, N. H.
1986-01-01
Measurements of low-energy ions made by the retarding ion mass spectrometer (RIMS) onboard the Dynamics Explorer 1 (DE 1) satellite are used to study some aspects of 'body-plasma interactions' in the terrestrial plasmasphere. Preliminary results are presented, yielding the degree of H+ and He+ ion depletion in the wake of the satellite in terms of specific and average ion Mach numbers, average ion mass, body size normalized to ionic Debye length, and body potential normalized to ion thermal energy. Some results from the RIMS measurements are compared with relevant results from the Explorer 31 and the Atmosphere Explorer C ionospheric satellites. Wake depletion is found to vary approximately linearly for small bodies (R-sub-Di less than about 12) and exponentially for large bodies (R-sub-Di greater than 50).
DOE Office of Scientific and Technical Information (OSTI.GOV)
Muto, Hideshi; Ohshiro, Yukimitsu; Kawasaki, Katsunori
2013-04-19
In the past decade, we have developed extremely long-lived carbon stripper foils of 1-50 {mu}g/cm{sup 2} thickness prepared by a heavy ion beam sputtering method. These foils were mainly used for low energy heavy ion beams. Recently, high energy negative Hydrogen and heavy ion accelerators have started to use carbon stripper foils of over 100 {mu}g/cm{sup 2} in thickness. However, the heavy ion beam sputtering method was unsuccessful in production of foils thicker than about 50 {mu}g/cm{sup 2} because of the collapse of carbon particle build-up from substrates during the sputtering process. The reproduction probability of the foils was lessmore » than 25%, and most of them had surface defects. However, these defects were successfully eliminated by introducing higher beam energies of sputtering ions and a substrate heater during the sputtering process. In this report we describe a highly reproducible method for making thick carbon stripper foils by a heavy ion beam sputtering with a Krypton ion beam.« less
High-intensity low energy titanium ion implantation into zirconium alloy
NASA Astrophysics Data System (ADS)
Ryabchikov, A. I.; Kashkarov, E. B.; Pushilina, N. S.; Syrtanov, M. S.; Shevelev, A. E.; Korneva, O. S.; Sutygina, A. N.; Lider, A. M.
2018-05-01
This research describes the possibility of ultra-high dose deep titanium ion implantation for surface modification of zirconium alloy Zr-1Nb. The developed method based on repetitively pulsed high intensity low energy titanium ion implantation was used to modify the surface layer. The DC vacuum arc source was used to produce metal plasma. Plasma immersion titanium ions extraction and their ballistic focusing in equipotential space of biased electrode were used to produce high intensity titanium ion beam with the amplitude of 0.5 A at the ion current density 120 and 170 mA/cm2. The solar eclipse effect was used to prevent vacuum arc titanium macroparticles from appearing in the implantation area of Zr sample. Titanium low energy (mean ion energy E = 3 keV) ions were implanted into zirconium alloy with the dose in the range of (5.4-9.56) × 1020 ion/cm2. The effect of ion current density, implantation dose on the phase composition, microstructure and distribution of elements was studied by X-ray diffraction, scanning electron microscopy and glow-discharge optical emission spectroscopy, respectively. The results show the appearance of Zr-Ti intermetallic phases of different stoichiometry after Ti implantation. The intermetallic phases are transformed from both Zr0.7Ti0.3 and Zr0.5Ti0.5 to single Zr0.6Ti0.4 phase with the increase in the implantation dose. The changes in phase composition are attributed to Ti dissolution in zirconium lattice accompanied by the lattice distortions and appearance of macrostrains in intermetallic phases. The depth of Ti penetration into the bulk of Zr increases from 6 to 13 μm with the implantation dose. The hardness and wear resistance of the Ti-implanted zirconium alloy were increased by 1.5 and 1.4 times, respectively. The higher current density (170 mA/cm2) leads to the increase in the grain size and surface roughness negatively affecting the tribological properties of the alloy.
Double matrix effect in Low Energy Ion Scattering from La surfaces
NASA Astrophysics Data System (ADS)
Zameshin, Andrey A.; Yakshin, Andrey E.; Sturm, Jacobus M.; Brongerma, Hidde H.; Bijkerk, Fred
2018-05-01
Low Energy Ion Scattering (LEIS) has been performed on several lanthanum-based surfaces. Strong subsurface matrix effects - dependence of surface scattered He+ ion yield on the composition of subsurface layer - have been observed. The ion yield of He+ scattered by La differed by a factor of up to 2.5 for different surfaces, while only the La peak was visible in the spectra. To study these effects and enable surface quantification, He+ ion yields have been measured in a range of incident He+ energies from 1000 to 7500 eV for LaB6, La2O3, oxidized La and pure La surfaces. The investigation showed that as many as two simultaneous matrix effects are present, each one driven by a separate charge exchange mechanism. The first one is a resonant neutralization from the conduction band of La to an excited state of the He+ ion. It depends on the work function of the surface, which is lowered significantly when La interacts with O or B. The second mechanism is quasiresonant charge transfer between bound La levels and He 1s, which creates characteristic oscillations in the energy dependence of ion yields. The exact structure of the oscillations depends on small changes in binding energies of interacting La levels. This is the first time quasiresonant charge transfer is proven to be present in La. It is likely that La 5p orbitals participate in this resonance, which can be the first clear observation of a resonance between p and s orbitals in LEIS. This type of resonance was previously believed to be absent because of strong damping. We also demonstrated that despite the complex matrix effect precise measurements over a wide energy range allow quantification of the atomic composition of La-based surfaces.
NASA Astrophysics Data System (ADS)
Gehrke, T.; Burigo, L.; Arico, G.; Berke, S.; Jakubek, J.; Turecek, D.; Tessonnier, T.; Mairani, A.; Martišíková, M.
2017-04-01
In the field of ion-beam radiotherapy and space applications, measurements of the energy deposition of single ions in thin layers are of interest for dosimetry and imaging. The present work investigates the capability of a pixelated detector Timepix to measure the energy deposition of single ions in therapeutic proton, helium- and carbon-ion beams in a 300 μm-thick sensitive silicon layer. For twelve different incident beams, the measured energy deposition distributions of single ions are compared to the expected energy deposition spectra, which were predicted by detailed Monte Carlo simulations using the FLUKA code. A methodology for the analysis of the measured data is introduced in order to identify and reject signals that are either degraded or caused by multiple overlapping ions. Applying a newly proposed linear recalibration, the energy deposition measurements are in good agreement with the simulations. The twelve measured mean energy depositions between 0.72 MeV/mm and 56.63 MeV/mm in a partially depleted silicon sensor do not deviate more than 7% from the corresponding simulated values. Measurements of energy depositions above 10 MeV/mm with a fully depleted sensor are found to suffer from saturation effects due to the too high per-pixel signal. The utilization of thinner sensors, in which a lower signal is induced, could further improve the performance of the Timepix detector for energy deposition measurements.
Ford, F.C.; Ruff, J.W.; Zizzo, S.G.; Cook, B.
1958-11-11
An ion source is described adapted for pulsed operation and producing copious quantities of ions with a particular ion egress geometry. The particular source construction comprises a conical member having a conducting surface formed of a metal with a gas occladed therein and narrow non-conducting portions hereon dividing the conducting surface. A high voltage pulse is applied across the conducting surface or producing a discharge across the surface. After the gas ions have been produced by the discharge, the ions are drawn from the source in a diverging conical beam by a specially constructed accelerating electrode.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Martin, Ina T.; Zhou Jie; Fisher, Ellen R.
2006-07-01
Ion energy distribution (IED) measurements are reported for ions in the plasma molecular beam source of the imaging of radicals interacting with surfaces (IRIS) apparatus. The IEDs and relative intensities of nascent ions in C{sub 3}F{sub 8} and C{sub 4}F{sub 8} plasma molecular beams were measured using a Hiden PSM003 mass spectrometer mounted on the IRIS main chamber. The IEDs are complex and multimodal, with mean ion energies ranging from 29 to 92 eV. Integrated IEDs provided relative ion intensities as a function of applied rf power and source pressure. Generally, higher applied rf powers and lower source pressures resultedmore » in increased ion intensities and mean ion energies. Most significantly, a comparison to CF{sub 2} surface interaction measurements previously made in our laboratories reveals that mean ion energies are directly and linearly correlated to CF{sub 2} surface production in these systems.« less
Two types of energy-dispersed ion structures at the plasma sheet boundary
NASA Astrophysics Data System (ADS)
Sauvaud, J.-A.; Kovrazhkin, R. A.
2004-12-01
We study two main types of ion energy dispersions observed in the energy range ˜1 to 14 keV on board the Interball-Auroral (IA) satellite at altitudes 2-3 RE at the poleward boundary of the plasma sheet. The first type of structure is named velocity dispersed ion structures (VDIS). It is known that VDIS represent a global proton structure with a latitudinal width of ˜0.7-2.5°, where the ion overall energy increases with latitude. IA data allow to show that VDIS are made of substructures lasting for ˜1-3 min. Inside each substructure, high-energy protons arrive first, regardless of the direction of the plasma sheet boundary crossing. A near-continuous rise of the maximal and minimal energies of consecutive substructures with invariant latitude characterizes VDIS. The second type of dispersed structure is named time-of-flight dispersed ion structures (TDIS). TDIS are recurrent sporadic structures in H+ (and also O+) with a quasi-period of ˜3 min and a duration of ˜1-3 min. The maximal energy of TDIS is rather constant and reaches ≥14 keV. During both poleward and equatorward crossings of the plasma sheet boundary, inside each TDIS, high-energy ions arrive first. These structures are accompanied by large fluxes of upflowing H+ and O+ ions with maximal energies up to 5-10 keV. In association with TDIS, bouncing H+ clusters are observed in quasi-dipolar magnetic field tubes, i.e., equatorward from TDIS. The electron populations generally have different properties during observations of VDIS and TDIS. The electron flux accompanying VDIS first increases smoothly and then decreases after Interball-Auroral has passed through the proton structure. The average electron energy in the range ˜0.5-2 keV is typical for electrons from the plasma sheet boundary layer (PSBL). The electron fluxes associated with TDIS increases suddenly at the polar boundary of the auroral zone. Their average energy, reaching ˜5-8 keV, is typical for CPS. A statistical analysis shows that
Centrifugally Stimulated Exospheric Ion Escape at Mercury
NASA Technical Reports Server (NTRS)
Delcourt, Dominique; Seki, K.; Terada, N.; Moore, Thomas E.
2012-01-01
We investigate the transport of ions in the low-altitude magnetosphere magnetosphere of Mercury. We show that, because of small spatial scales, the centrifugal effect due to curvature of the E B drift paths can lead to significant particle energization in the parallel direction. We demonstrate that because of this effect, ions with initial speed smaller than the escape speed such as those produced via thermal desorption can overcome gravity and escape into the magnetosphere. The escape route of this low-energy exosphere originating material is largely controlled by the magnetospheric convection rate. This escape route spreads over a narrower range of altitudes when the convection rate increases. Bulk transport of low-energy planetary material thus occurs within a limited region of space once moderate magnetospheric convection is established. These results suggest that, via release of material otherwise gravitationally trapped, the E B related centrifugal acceleration is an important mechanism for the net supply of plasma to the magnetosphere of Mercury.
Time of Flight based diagnostics for high energy laser driven ion beams
NASA Astrophysics Data System (ADS)
Scuderi, V.; Milluzzo, G.; Alejo, A.; Amico, A. G.; Booth, N.; Cirrone, G. A. P.; Doria, D.; Green, J.; Kar, S.; Larosa, G.; Leanza, R.; Margarone, D.; McKenna, P.; Padda, H.; Petringa, G.; Pipek, J.; Romagnani, L.; Romano, F.; Schillaci, F.; Borghesi, M.; Cuttone, G.; Korn, G.
2017-03-01
Nowadays the innovative high power laser-based ion acceleration technique is one of the most interesting challenges in particle acceleration field, showing attractive characteristics for future multidisciplinary applications, including medical ones. Nevertheless, peculiarities of optically accelerated ion beams make mandatory the development of proper transport, selection and diagnostics devices in order to deliver stable and controlled ion beams for multidisciplinary applications. This is the main purpose of the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline that will be realized and installed within 2018 at the ELI-Beamlines research center in the Czech Republic, where laser driven high energy ions, up to 60 MeV/n, will be available for users. In particular, a crucial role will be played by the on-line diagnostics system, recently developed in collaboration with INFN-LNS (Italy), consisting of TOF detectors, placed along the beamline (at different detection distances) to provide online monitoring of key characteristics of delivered beams, such as energy, fluence and ion species. In this contribution an overview on the ELIMAIA available ion diagnostics will be briefly given along with the preliminary results obtained during a test performed with high energy laser-driven proton beams accelerated at the VULCAN PW-laser available at RAL facility (U.K.).
The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra
NASA Astrophysics Data System (ADS)
Murphy, T. J.
2014-07-01
Measuring the width of the energy spectrum of fusion-produced neutrons from deuterium (DD) or deuterium-tritium (DT) plasmas is a commonly used method for determining the ion temperature in inertial confinement fusion (ICF) implosions. In a plasma with a Maxwellian distribution of ion energies, the spread in neutron energy arises from the thermal spread in the center-of-mass velocities of reacting pairs of ions. Fluid velocities in ICF are of a similar magnitude as the center-of-mass velocities and can lead to further broadening of the neutron spectrum, leading to erroneous inference of ion temperature. Motion of the reacting plasma will affect DD and DT neutrons differently, leading to disagreement between ion temperatures inferred from the two reactions. This effect may be a contributor to observations over the past decades of ion temperatures higher than expected from simulations, ion temperatures in disagreement with observed yields, and different temperatures measured in the same implosion from DD and DT neutrons. This difference in broadening of DD and DT neutrons also provides a measure of turbulent motion in a fusion plasma.
S -matrix calculations of energy levels of sodiumlike ions
Sapirstein, J.; Cheng, K. T.
2015-06-24
A recent S -matrix-based QED calculation of energy levels of the lithium isoelectronic sequence is extended to the general case of a valence electron outside an arbitrary filled core. Emphasis is placed on modifications of the lithiumlike formulas required because more than one core state is present, and an unusual feature of the two-photon exchange contribution involving autoionizing states is discussed. Here, the method is illustrated with a calculation of the energy levels of sodiumlike ions, with results for 3s 1/2, 3p 1/2, and 3p 3/2 energies tabulated for the range Z = 30 – 100 . Comparison with experimentmore » and other calculations is given, and prospects for extension of the method to ions with more complex electronic structure discussed.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
McLaughlin, B. M.; Ballance, C. P.; Schippers, S.
2016-02-22
Experimental and theoretical results are reported for single-photon single ionization of W 2+ and W 3+ tungsten ions. Experiments were performed at the photon-ion merged-beam setup of the Advanced Light Source in Berkeley. Absolute cross sections and detailed energy scans were measured over an energy range 20-90 eV at a bandwidth of 100 meV. Broad peak features with widths typically around 5 eV have been observed with almost no narrow resonances present in the investigated energy range. Theoretical results were obtained from a Dirac-Coulomb R-matrix approach. The calculations were carried out for the lowest-energy terms of the investigated tungsten ionsmore » with levels 5s 25p 65d 4 5D J J = 0, 1, 2, 3, 4 for W 2+ and 5s 25p 65d 3 4F J' J ' = 3/2, 5/2, 7/2, 9/2 for W 3+. Assuming a statistically weighted distribution of ions in the initial ground-term levels there is good agreement of theory and experiment for W 3+ ions. However, for W 2+ ions at higher energies there is a factor of approximately two difference between experimental and theoretical cross sections.« less
NASA Technical Reports Server (NTRS)
Smart, M. C.; Krause, F. C.; Hwang, C.; West, W. C.; Soler, J.; Whitcanack, L. W.; Prakash, G. K. S.; Ratnakumar, B. V.
2012-01-01
(1) NASA is actively pursuing the development of advanced electrochemical energy storage and conversion devices for future lunar and Mars missions; (2) The Exploration Technology Development Program, Energy Storage Project is sponsoring the development of advanced Li-ion batteries and PEM fuel cell and regenerative fuel cell systems for the Altair Lunar Lander, Extravehicular Activities (EVA), and rovers and as the primary energy storage system for Lunar Surface Systems; (3) At JPL, in collaboration with NASA-GRC, NASA-JSC and industry, we are actively developing advanced Li-ion batteries with improved specific energy, energy density and safety. One effort is focused upon developing Li-ion battery electrolyte with enhanced safety characteristics (i.e., low flammability); and (4) A number of commercial applications also require Li-ion batteries with enhanced safety, especially for automotive applications.
Inverse Energy Dispersion of Energetic Ions Observed in the Magnetosheath
NASA Technical Reports Server (NTRS)
Lee, S. H.; Sibeck, D. G.; Hwang, K.-J.; Wang, Y.; Silveira, M. V. D.; Fok, M.-C.; Mauk, B. H.; Cohen, I. J.; Ruohoniemi, J. M.; Kitamura, N.;
2016-01-01
We present a case study of energetic ions observed by the Energetic Particle Detector (EPD) on the Magnetospheric Multiscale spacecraft in the magnetosheath just outside the subsolar magnetopause that occurred at 1000 UT on 8 December 2015. As the magnetopause receded inward, the EPD observed a burst of energetic (approximately 50-1000 keV) proton, helium, and oxygen ions that exhibited an inverse dispersion, with the lowest energy ions appearing first. The prolonged interval of fast antisunward flow observed in the magnetosheath and transient increases in the H components of global ground magnetograms demonstrate that the burst appeared at a time when the magnetosphere was rapidly compressed. We attribute the inverse energy dispersion to the leakage along reconnected magnetic field lines of betatron-accelerated energetic ions in the magnetosheath, and a burst of reconnection has an extent of about 1.5 R(sub E) using combined Super Dual Auroral Radar Network radar and EPD observations.
N-Ω Interaction from High-Energy Heavy Ion Collisions
NASA Astrophysics Data System (ADS)
Morita, Kenji; Ohnishi, Akira; Hatsuda, Tetsuo
We discuss possible observation of the N-Ω interaction from intensity correlation function in high energy heavy ion collisions. Recently a lattice QCD simulation by the HAL QCD collaboration predicts the existence of a N-Ω bound state in the 5S2 channel. We adopt the N-Ω interaction potential obtained by the lattice simulation and use it to calculate the N-Ω correlation function. We also study the variation of the correlation function with respect to the change of the binding energy and scattering parameters. Our result indicates that heavy ion collisions at RHIC and LHC may provide information on the possible existence of the N-Ω dibaryon.
Controlled removal of ceramic surfaces with combination of ions implantation and ultrasonic energy
Boatner, Lynn A.; Rankin, Janet; Thevenard, Paul; Romana, Laurence J.
1995-01-01
A method for tailoring or patterning the surface of ceramic articles is provided by implanting ions to predetermined depth into the ceramic material at a selected surface location with the ions being implanted at a fluence and energy adequate to damage the lattice structure of the ceramic material for bi-axially straining near-surface regions of the ceramic material to the predetermined depth. The resulting metastable near-surface regions of the ceramic material are then contacted with energy pulses from collapsing, ultrasonically-generated cavitation bubbles in a liquid medium for removing to a selected depth the ion-damaged near-surface regions containing the bi-axially strained lattice structure from the ceramic body. Additional patterning of the selected surface location on the ceramic body is provided by implanting a high fluence of high-energy, relatively-light ions at selected surface sites for relaxing the bi-axial strain in the near-surface regions defined by these sites and thereby preventing the removal of such ion-implanted sites by the energy pulses from the collapsing ultrasonic cavitation bubbles.
Measurements of the energy distribution of a high brightness rubidium ion beam.
Ten Haaf, G; Wouters, S H W; Nijhof, D F J; Mutsaers, P H A; Vredenbregt, E J D
2018-07-01
The energy distribution of a high brightness rubidium ion beam, which is intended to be used as the source for a focused ion beam instrument, is measured with a retarding field analyzer. The ions are created from a laser-cooled and compressed atomic beam by two-step photoionization in which the ionization laser power is enhanced in a build-up cavity. Particle tracing simulations are performed to ensure the analyzer is able to resolve the distribution. The lowest achieved full width 50% energy spread is (0.205 ± 0.006) eV, which is measured at a beam current of 9 pA. The energy spread originates from the variation in the ionization position of the ions which are created inside an extraction electric field. This extraction field is essential to limit disorder-induced heating which can decrease the ion beam brightness. The ionization position distribution is limited by a tightly focused excitation laser beam. Energy distributions are measured for various ionization and excitation laser intensities and compared with calculations based on numerical solutions of the optical Bloch equations including ionization. A good agreement is found between measurements and calculations. Copyright © 2018 Elsevier B.V. All rights reserved.
Sputtering of cobalt and chromium by argon and xenon ions near the threshold energy region
NASA Technical Reports Server (NTRS)
Handoo, A. K.; Ray, P. K.
1993-01-01
Sputtering yields of cobalt and chromium by argon and xenon ions with energies below 50 eV are reported. The targets were electroplated on copper substrates. Measurable sputtering yields were obtained from cobalt with ion energies as low as 10 eV. The ion beams were produced by an ion gun. A radioactive tracer technique was used for the quantitative measurement of the sputtering yield. Co-57 and Cr-51 were used as tracers. The yield-energy curves are observed to be concave, which brings into question the practice of finding threshold energies by linear extrapolation.
Radiation pressure acceleration: The factors limiting maximum attainable ion energy
Bulanov, S. S.; Esarey, E.; Schroeder, C. B.; ...
2016-04-15
Radiation pressure acceleration (RPA) is a highly efficient mechanism of laser-driven ion acceleration, with near complete transfer of the laser energy to the ions in the relativistic regime. However, there is a fundamental limit on the maximum attainable ion energy, which is determined by the group velocity of the laser. The tightly focused laser pulses have group velocities smaller than the vacuum light speed, and, since they offer the high intensity needed for the RPA regime, it is plausible that group velocity effects would manifest themselves in the experiments involving tightly focused pulses and thin foils. However, in this case,more » finite spot size effects are important, and another limiting factor, the transverse expansion of the target, may dominate over the group velocity effect. As the laser pulse diffracts after passing the focus, the target expands accordingly due to the transverse intensity profile of the laser. Due to this expansion, the areal density of the target decreases, making it transparent for radiation and effectively terminating the acceleration. The off-normal incidence of the laser on the target, due either to the experimental setup, or to the deformation of the target, will also lead to establishing a limit on maximum ion energy.« less
Live cell imaging combined with high-energy single-ion microbeam
NASA Astrophysics Data System (ADS)
Guo, Na; Du, Guanghua; Liu, Wenjing; Guo, Jinlong; Wu, Ruqun; Chen, Hao; Wei, Junzhe
2016-03-01
DNA strand breaks can lead to cell carcinogenesis or cell death if not repaired rapidly and efficiently. An online live cell imaging system was established at the high energy microbeam facility at the Institute of Modern Physics to study early and fast cellular response to DNA damage after high linear energy transfer ion radiation. The HT1080 cells expressing XRCC1-RFP were irradiated with single high energy nickel ions, and time-lapse images of the irradiated cells were obtained online. The live cell imaging analysis shows that strand-break repair protein XRCC1 was recruited to the ion hit position within 20 s in the cells and formed bright foci in the cell nucleus. The fast recruitment of XRCC1 at the ion hits reached a maximum at about 200 s post-irradiation and then was followed by a slower release into the nucleoplasm. The measured dual-exponential kinetics of XRCC1 protein are consistent with the proposed consecutive reaction model, and the measurements obtained that the reaction rate constant of the XRCC1 recruitment to DNA strand break is 1.2 × 10-3 s-1 and the reaction rate constant of the XRCC1 release from the break-XRCC1 complex is 1.2 × 10-2 s-1.
Pappas, E; Maris, T G; Papadakis, A; Zacharopoulou, F; Damilakis, J; Papanikolaou, N; Gourtsoyiannis, N
2006-10-01
The aim of this work is to investigate experimentally the detector size effect on narrow beam profile measurements. Polymer gel and magnetic resonance imaging dosimetry was used for this purpose. Profile measurements (Pm(s)) of a 5 mm diameter 6 MV stereotactic beam were performed using polymer gels. Eight measurements of the profile of this narrow beam were performed using correspondingly eight different detector sizes. This was achieved using high spatial resolution (0.25 mm) two-dimensional measurements and eight different signal integration volumes A X A X slice thickness, simulating detectors of different size. "A" ranged from 0.25 to 7.5 mm, representing the detector size. The gel-derived profiles exhibited increased penumbra width with increasing detector size, for sizes >0.5 mm. By extrapolating the gel-derived profiles to zero detector size, the true profile (Pt) of the studied beam was derived. The same polymer gel data were also used to simulate a small-volume ion chamber profile measurement of the same beam, in terms of volume averaging. The comparison between these results and actual corresponding small-volume chamber profile measurements performed in this study, reveal that the penumbra broadening caused by both volume averaging and electron transport alterations (present in actual ion chamber profile measurements) is a lot more intense than that resulted by volume averaging effects alone (present in gel-derived profiles simulating ion chamber profile measurements). Therefore, not only the detector size, but also its composition and tissue equivalency is proved to be an important factor for correct narrow beam profile measurements. Additionally, the convolution kernels related to each detector size and to the air ion chamber were calculated using the corresponding profile measurements (Pm(s)), the gel-derived true profile (Pt), and convolution theory. The response kernels of any desired detector can be derived, allowing the elimination of the errors
Interaction of a sodium ion with the water liquid-vapor interface
NASA Technical Reports Server (NTRS)
Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)
1989-01-01
Molecular dynamics results are presented for the density profile of a sodium ion near the water liquid-vapor interface at 320 K. These results are compared with the predictions of a simple dielectric model for the interaction of a monovalent ion with this interface. The interfacial region described by the model profile is too narrow and the profile decreases too abruptly near the solution interface. Thus, the simple model does not provide a satisfactory description of the molecular dynamics results for ion positions within two molecular diameters from the solution interface where appreciable ion concentrations are observed. These results suggest that surfaces associated with dielectric models of ionic processes at aqueous solution interfaces should be located at least two molecular diameters inside the liquid phase. A free energy expense of about 2 kcal/mol is required to move the ion within two molecular layers of the free water liquid-vapor interface.
Orthogonal time-of-flight mass spectrometry of an ion beam with a broad kinetic energy profile.
Miller, S W; Prince, B D; Bemish, R J
2017-10-01
A combined experimental and modeling effort is undertaken to assess a detection system composed of an orthogonal extraction time-of-flight (TOF) mass spectrometer coupled to a continuous ion source emitting an ion beam with kinetic energy of several hundred eV. The continuous ion source comprises an electrospray capillary system employing an undiluted ionic liquid emitting directly into vacuum. The resulting ion beam consists of ions with kinetic energy distributions of width greater than a hundred of eV and mass-to-charge (m/q) ratios ranging from 111 to 500 000 amu/q. In particular, the investigation aims to demonstrate the kinetic energy resolution along the ion beam axis (axial) of orthogonally extracted ions in measurements of the axial kinetic energy-specific mass spectrum, mass flow rate, and total ion current. The described instrument is capable of simultaneous measurement of a broad m/q range in a single acquisition cycle with approximately 25 eV/q axial kinetic energy resolution. Mass resolutions of ∼340 (M/ΔM, FWHM) were obtained for ions at m/q = 1974. Comparison of the orthogonally extracted TOF mass spectrum to mass flow and ion current measurements obtained with a quartz-crystal microbalance and Faraday cup, respectively, shows reasonable numeric agreement and qualitative agreement in the trend as a function of energy defect.
The stopping power and energy straggling of heavy ions in silicon nitride and polypropylene
NASA Astrophysics Data System (ADS)
Mikšová, R.; Hnatowicz, V.; Macková, A.; Malinský, P.; Slepička, P.
2015-07-01
The stopping power and energy straggling of 12C3+ and 16O3+ ions with energies between 4.5 and 7.8 MeV in a 0.166-μm-thin silicon nitride and in 4-μm-thin polypropylene foils were measured by means of an indirect transmission method using a half-covered PIPS detector. Ions scattered from a thin gold layer under a scattering angle of 150° were used. The energy spectra of back-scattered and decelerated ions were registered and evaluated simultaneously. The measured stopping powers were compared with the theoretical predictions simulated by SRIM-2008 and MSTAR codes. SRIM prediction of energy stopping is reasonably close to the experimentally obtained values comparing to MSTAR values. Better agreement between experimental and predicted data was observed for C3+ ion energy losses comparing to O3+ ions. The experimental data from Paul's database and our previous experimental data were also discussed. The obtained experimental energy-straggling data were compared to those calculated by using Bohr's, Yang's models etc. The predictions by Yang are in good agreement with our experiment within a frame of uncertainty of 25%.
Structure of High Energy, Heavy Ions in Venus' Upper Ionosphere
NASA Astrophysics Data System (ADS)
Persson, Moa; Futaana, Yoshifumi; Nilsson, Hans; Stenberg Wieser, Gabriella; Hamrin, Maria; Fedorov, Andrei; Barabash, Stas
2017-04-01
The solar wind interacts with the atmosphere of Venus, and can reach directly down to the ionosphere. The interaction has previously been studied using the Pioneer Venus mission (PVO) and is now known to cause variations in the density in the ionosphere [Taylor et al., 1980], a transport of ions towards the night side [Knudsen et al., 1980], and an outflow of ions from the atmosphere [Barabash et al., 2007]. Measurements made by PVO showed that the main constituents of Venus ionosphere in the altitude range 150-400 km is the O+ and O2+ ions, where the former dominates from 180 km and higher, and the latter dominates from 180 km down to 150 km [Taylor et al., 1980]. New measurements, made by the Ion Mass Analyzer (IMA) onboard the Venus Express spacecraft, reveal the high-energy (10 eV to 15 keV) plasma characteristics in the ionosphere of Venus. Using the data collected during the low altitude (down to 130 km) pericentre passages during the aerobraking time period, we are able to extract the height profile of the total heavy ion content (O+ and O2+ ions) of Venus ionosphere. The results show two scale heights separated at 200 km; 10 km for <200 km and 100 km for >200 km. We interpret the results as two heavy ion components, namely, the O+ ions are dominant for >200 km, while the O2+ is dominant for <200 km. This is consistent with previous results from PVO. Furthermore, we attempt several methods of mass separation, to extract the two ion components of the scale height profiles, (O+ and O2+). First method is to use the moderate mass separation capabilities of the IMA instrument. The individual mass spectra are fitted by two Gaussian curves, representing O+ and O2+, derived from ground calibration information. The second method uses the energy spectrum, which sometimes has two discrete peaks. By assuming the same velocity for different components in the spacecraft reference frame (resulting in different energy for different masses), we can separate the composition
Ripple pattern formation on silicon surfaces by low-energy ion-beam erosion: Experiment and theory
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ziberi, B.; Frost, F.; Rauschenbach, B.
The topography evolution of Si surfaces during low-energy noble-gas ion-beam erosion (ion energy {<=}2000 eV) at room temperature has been studied. Depending on the ion-beam parameters, self-organized ripple patterns evolve on the surface with a wavelength {lambda}<100 nm. Ripple patterns were found to occur at near-normal ion incidence angles (5 deg. -30 deg.) with the wave vector oriented parallel to the ion-beam direction. The ordering and homogeneity of these patterns increase with ion fluence, leading to very-well-ordered ripples. The ripple wavelength remains constant with ion fluence. Also, the influence of ion energy on the ripple wavelength is investigated. Additionally itmore » is shown that the mass of the bombarding ion plays a decisive role in the ripple formation process. Ripple patterns evolve for Ar{sup +},Kr{sup +}, and Xe{sup +} ions, while no ripples are observed using Ne{sup +} ions. These results are discussed in the context of continuum theories and by using Monte Carlo simulations.« less
A thermalized ion explosion model for high energy sputtering and track registration
NASA Technical Reports Server (NTRS)
Seiberling, L. E.; Griffith, J. E.; Tombrello, T. A.
1980-01-01
A velocity spectrum of neutral sputtered particles as well as a low resolution mass spectrum of sputtered molecular ions was measured for 4.74 MeV F-19(+2) incident of UF4. The velocity spectrum is dramatically different from spectra taken with low energy (keV) bombarding ions, and is shown to be consistent with a hot plasma of atoms in thermal equilibrium inside the target. A thermalized ion explosion model is proposed for high energy sputtering which is expected to describe track formation in dielectric materials. The model is shown to be consistent with the observed total sputtering yield and the dependence of the yield on the primary ionization rate of the incident ion.
Electromagnetic ion/ion cyclotron instability - Theory and simulations
NASA Technical Reports Server (NTRS)
Winske, D.; Omidi, N.
1992-01-01
Linear theory and 1D and 2D hybrid simulations are employed to study electromagnetic ion/ion cyclotron (EMIIC) instability driven by the relative streaming of two field-aligned ion beams. The characteristics of the instability are studied as a function of beam density, propagation angle, electron-ion temperature ratios, and ion beta. When the propagation angle is near 90 deg the EMIIC instability has the characteristics of an electrostatic instability, while at smaller angles electromagnetic effects play a significant role as does strong beam coupling. The 2D simulations point to a narrowing of the wave spectrum and accompanying coherent effects during the linear growth stage of development. The EMIIC instability is an important effect where ion beta is low such as in the plasma-sheet boundary layer and upstream of slow shocks in the magnetotail.
NASA Astrophysics Data System (ADS)
Mensah, Samuel; Abu-Safe, Husam; Naseem, Hameed; Gordon, Matt
2012-02-01
Ion energy distributions of sputtered Si particles have been measured by an energy-resolved mass spectrometer, and we correlate the results with measured thin film properties. The plasmas have been generated in a conventional magnetron chamber powered at 150W, 13.56MHz at hydrogen flow rates ranging from 0-25sccm. Various Hn^+, SiHn^+, SiHn fragments (with n = 1, 2, 3) together with Ar^+ and ArH^+ species were detected in the discharge. The most important species for the film deposition is SiHn with n = 0,1,2, and H fragments affect the hydrogen content in the material. The flux of Ar^+ decreases and that of ArH^+ increases when the hydrogen flow rate was increased. However both fluxes saturate at hydrogen flow rates above 15sccm. Plasma parameters, such as plasma potential Vp, electron density ne and electron energy Te, are measured with the Langmuir probe. The ion energy distribution (IED) of all prominent species in the plasma is measured with an energy resolved mass analyzer. The plasma parameters decreased with increasing hydrogen flow rate; Vp, ne and Te decreased from 36.5V, 7.2x10^15 m-3, 5.6eV to 32.8, 2.2x10^15m-3 and 3.8eV respectively. The ion energy of the heavy species, Ar, Ar^+, ArH, ArH^+, SiHn and SiHn^+ radicals have ion energies comparable to the plasma potential. Analysis of the IEDs shows an inter-dependence of the species and their contribution to the thin film growth and properties.
Formation of a1 Ions Directly from Oxazolone b2 Ions: an Energy-Resolved and Computational Study
NASA Astrophysics Data System (ADS)
Bythell, Benjamin J.; Harrison, Alex G.
2015-05-01
It is well-known that oxazolone b2 ions fragment extensively by elimination of CO to form a2 ions, which often fragment further to form a1 ions. Less well-known is that some oxazolone b2 ions may fragment directly to form a1 ions. The present study uses energy-resolved collision-induced dissociation experiments to explore the occurrence of the direct b2→a1 fragmentation reaction. The experimental results show that the direct b2→a1 reaction is generally observed when Gly is the C-terminal residue of the oxazolone. When the C-terminal residue is more complex, it is able to provide increased stability of the a2 product in the b2→a2 fragmentation pathway. Our computational studies of the relative critical reaction energies for the b2→a2 reaction compared with those for the b2→a1 reaction provide support that the critical reaction energies are similar for the two pathways when the C-terminal residue of the oxazolone is Gly. By contrast, when the nitrogen of the oxazolone ring in the b2 ion does not bear a hydrogen, as in the Ala-Sar and Tyr-Sar (Sar = N-methylglycine) oxazolone b2 ions, a1 ions are not formed but rather neutral imine elimination from the N-terminus of the b2 ion becomes a dominant fragmentation reaction. The M06-2X/6-31+G(d,p) density functional theory calculations are in general agreement with the experimental data for both types of reaction. In contrast, the B3LYP/6-31+G(d,p) model systematically underestimates the barriers of these SN2-like b2→a1 reaction. The difference between the two methods of barrier calculation are highly significant ( P < 0.001) for the b2→a1 reaction, but only marginally significant ( P = 0.05) for the b2→a2 reaction. The computations provide further evidence of the limitations of the B3LYP functional when describing SN2-like reactions.
Study of energy transfer mechanism from ZnO nanocrystals to Eu(3+) ions.
Mangalam, Vivek; Pita, Kantisara; Couteau, Christophe
2016-12-01
In this work, we investigate the efficient energy transfer occurring between ZnO nanocrystals (ZnO-nc) and europium (Eu(3+)) ions embedded in a SiO2 matrix prepared using the sol-gel technique. We show that a strong red emission was observed at 614 nm when the ZnO-nc were excited using a continuous optical excitation at 325 nm. This emission is due to the radiative (5)D0 → (7)F2 de-excitation of the Eu(3+) ions and has been conclusively shown to be due to the energy transfer from the excited ZnO-nc to the Eu(3+) ions. The photoluminescence excitation spectra are also examined in this work to confirm the energy transfer from ZnO-nc to the Eu(3+) ions. Furthermore, we study various de-excitation processes from the excited ZnO-nc and their contribution to the energy transfer to Eu(3+) ions. We also report the optimum fabrication process for maximum red emission at 614 nm from the samples where we show a strong dependence on the annealing temperature and the Eu(3+) concentration in the sample. The maximum red emission is observed with 12 mol% Eu(3+) annealed at 450 °C. This work provides a better understanding of the energy transfer mechanism from ZnO-nc to Eu(3+) ions and is important for applications in photonics, especially for light emitting devices.
NASA Astrophysics Data System (ADS)
Nishimura, Tomoaki
2016-03-01
A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of 16O(4He, 4He)16O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.
Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries
NASA Astrophysics Data System (ADS)
Li, Jianlin; Du, Zhijia; Ruther, Rose E.; AN, Seong Jin; David, Lamuel Abraham; Hays, Kevin; Wood, Marissa; Phillip, Nathan D.; Sheng, Yangping; Mao, Chengyu; Kalnaus, Sergiy; Daniel, Claus; Wood, David L.
2017-09-01
Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by 70% from 2008 to 2015, the current battery pack cost (268/kWh in 2015) is still >2 times what the USABC targets (125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. This article discusses three major aspects for cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.
Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries
Li, Jianlin; Du, Zhijia; Ruther, Rose E.; ...
2017-06-12
Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by ~70% from 2008 to 2015, the current battery pack cost (268/kWh in 2015) is still >2 times what the USABC targets (125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. Here, this article discusses three major aspects formore » cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.« less
Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries
DOE Office of Scientific and Technical Information (OSTI.GOV)
Li, Jianlin; Du, Zhijia; Ruther, Rose E.
Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by ~70% from 2008 to 2015, the current battery pack cost (268/kWh in 2015) is still >2 times what the USABC targets (125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. Here, this article discusses three major aspects formore » cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.« less
Berengut, J C; Dzuba, V A; Flambaum, V V; Ong, A
2012-08-17
We study electronic transitions in highly charged Cf ions that are within the frequency range of optical lasers and have very high sensitivity to potential variations in the fine-structure constant, α. The transitions are in the optical range despite the large ionization energies because they lie on the level crossing of the 5f and 6p valence orbitals in the thallium isoelectronic sequence. Cf(16+) is a particularly rich ion, having several narrow lines with properties that minimize certain systematic effects. Cf(16+) has very large nuclear charge and large ionization energy, resulting in the largest α sensitivity seen in atomic systems. The lines include positive and negative shifters.
A Variable Energy CW Compact Accelerator for Ion Cancer Therapy
DOE Office of Scientific and Technical Information (OSTI.GOV)
Johnstone, Carol J.; Taylor, J.; Edgecock, R.
2016-03-10
Cancer is the second-largest cause of death in the U.S. and approximately two-thirds of all cancer patients will receive radiation therapy with the majority of the radiation treatments performed using x-rays produced by electron linacs. Charged particle beam radiation therapy, both protons and light ions, however, offers advantageous physical-dose distributions over conventional photon radiotherapy, and, for particles heavier than protons, a significant biological advantage. Despite recognition of potential advantages, there is almost no research activity in this field in the U.S. due to the lack of clinical accelerator facilities offering light ion therapy in the States. In January, 2013, amore » joint DOE/NCI workshop was convened to address the challenges of light ion therapy [1], inviting more than 60 experts from diverse fields related to radiation therapy. This paper reports on the conclusions of the workshop, then translates the clinical requirements into accelerat or and beam-delivery technical specifications. A comparison of available or feasible accelerator technologies is compared, including a new concept for a compact, CW, and variable energy light ion accelerator currently under development. This new light ion accelerator is based on advances in nonscaling Fixed-Field Alternating gradient (FFAG) accelerator design. The new design concepts combine isochronous orbits with long (up to 4m) straight sections in a compact racetrack format allowing inner circulating orbits to be energy selected for low-loss, CW extraction, effectively eliminating the high-loss energy degrader in conventional CW cyclotron designs.« less
Low energy electrons and swift ion track structure in PADC
DOE Office of Scientific and Technical Information (OSTI.GOV)
Fromm, Michel; Quinto, Michele A.; Weck, Philippe F.
The current work aims at providing an accurate description of the ion track-structure in poly-allyl dyglycol carbonate (PADC) by using an up-to-date Monte-Carlo code-called TILDA-V (a French acronym for Transport d’Ions Lourds Dans l’Aqua & Vivo). In this simulation the ion track-structure in PADC is mainly described in terms of ejected electrons with a particular attention done to the Low Energy Electrons (LEEs). After a brief reminder of the most important channels through which LEEs are prone to break a chemical bond, we will report on the simulated energetic distributions of LEEs along an ion track in PADC for particularmore » incident energies located on both sides of the Bragg-peak position. Lastly, based on the rare data dealing with LEEs interaction with polymers or organic molecules, we will emphasise the role played by the LEEs in the formation of a latent track in PADC, and more particularly the one played by the sub-ionization electrons.« less
Low energy electrons and swift ion track structure in PADC
Fromm, Michel; Quinto, Michele A.; Weck, Philippe F.; ...
2015-05-27
The current work aims at providing an accurate description of the ion track-structure in poly-allyl dyglycol carbonate (PADC) by using an up-to-date Monte-Carlo code-called TILDA-V (a French acronym for Transport d’Ions Lourds Dans l’Aqua & Vivo). In this simulation the ion track-structure in PADC is mainly described in terms of ejected electrons with a particular attention done to the Low Energy Electrons (LEEs). After a brief reminder of the most important channels through which LEEs are prone to break a chemical bond, we will report on the simulated energetic distributions of LEEs along an ion track in PADC for particularmore » incident energies located on both sides of the Bragg-peak position. Lastly, based on the rare data dealing with LEEs interaction with polymers or organic molecules, we will emphasise the role played by the LEEs in the formation of a latent track in PADC, and more particularly the one played by the sub-ionization electrons.« less
NASA Astrophysics Data System (ADS)
Artemyev, A. V.; Vasko, I. Y.; Lutsenko, V. N.; Petrukovich, A. A.
2014-10-01
We investigate the formation of the high-energy (E ∈ [20,600] keV) ion population in the earth's magnetotail. We collect statistics of 4 years of Interball / Tail observations (1995-1998) in the vicinity of the neutral plane in the magnetotail region (X <-17 RE, |Y| ≤ 20 RE in geocentric solar magnetospheric (GSM) system). We study the dependence of high-energy ion spectra on the thermal-plasma parameters (the temperature Ti and the amplitude of bulk velocity vi) and on the magnetic-field component Bz. The ion population in the energy range E ∈ [20,600] keV can be separated in the thermal core and the power-law tail with the slope (index) ~ -4.5. Fluxes of the high-energy ion population increase with the growth of Bz, vi and especially Ti, but spectrum index seems to be independent on these parameters. We have suggested that the high-energy ion population is generated by small scale transient processes, rather than by the global reconfiguration of the magnetotail. We have proposed the relatively simple and general model of ion acceleration by transient bursts of the electric field. This model describes the power-law energy spectra and predicts typical energies of accelerated ions.
Live cell imaging combined with high-energy single-ion microbeam
DOE Office of Scientific and Technical Information (OSTI.GOV)
Guo, Na; Du, Guanghua, E-mail: gh-du@impcas.ac.cn; Liu, Wenjing
DNA strand breaks can lead to cell carcinogenesis or cell death if not repaired rapidly and efficiently. An online live cell imaging system was established at the high energy microbeam facility at the Institute of Modern Physics to study early and fast cellular response to DNA damage after high linear energy transfer ion radiation. The HT1080 cells expressing XRCC1-RFP were irradiated with single high energy nickel ions, and time-lapse images of the irradiated cells were obtained online. The live cell imaging analysis shows that strand-break repair protein XRCC1 was recruited to the ion hit position within 20 s in themore » cells and formed bright foci in the cell nucleus. The fast recruitment of XRCC1 at the ion hits reached a maximum at about 200 s post-irradiation and then was followed by a slower release into the nucleoplasm. The measured dual-exponential kinetics of XRCC1 protein are consistent with the proposed consecutive reaction model, and the measurements obtained that the reaction rate constant of the XRCC1 recruitment to DNA strand break is 1.2 × 10{sup −3} s{sup −1} and the reaction rate constant of the XRCC1 release from the break-XRCC1 complex is 1.2 × 10{sup −2} s{sup −1}.« less
Ion distribution in the hot spot of an inertial confinement fusion plasma
NASA Astrophysics Data System (ADS)
Tang, Xianzhu; Guo, Zehua; Berk, Herb
2012-10-01
Maximizing the fusion gain of inertial confinement fusion (ICF) for inertial fusion energy (IFE) applications leads to the standard scenario of central hot spot ignition followed by propagating burn wave through the cold/dense assembled fuel. The fact that the hot spot is surrounded by cold but dense fuel layer introduces subtle plasma physics which requires a kinetic description. Here we perform Fokker-Planck calculations and kinetic PIC simulations for an ICF plasma initially in pressure balance but having large temperature gradient over a narrow transition layer. The loss of the fast ion tail from the hot spot, which is important for fusion reactivity, is quantified by Fokker-Planck models. The role of electron energy transport and the ambipolar electric field is investigated via kinetic simulations and the fluid moment models. The net effect on both hot spot ion temperature and the ion tail distribution, and hence the fusion reactivity, is elucidated.
Measurement of alpha particle energy using windowless electret ion chambers.
Dua, S K; Kotrappa, P; Srivastava, R; Ebadian, M A; Stieff, L R
2002-10-01
Electret ion chambers are inexpensive, lightweight, robust, commercially available, passive, charge-integrating devices for accurate measurement of different ionizing radiations. In an earlier work a chamber of dimensions larger than the range of alpha particles having aluminized Mylar windows of different thickness was used for measurement of alpha radiation. Correlation between electret mid-point voltage, alpha particle energy, and response was developed and it was shown that this chamber could be used for estimating the effective energy of an unknown alpha source. In the present study, the electret ion chamber is used in the windowless mode so that the alpha particles dissipate their entire energy inside the volume, and the alpha particle energy is determined from the first principles. This requires that alpha disintegration rate be accurately known or measured by an alternate method. The measured energies were within 1 to 4% of the true values for different sources (230Th, 237Np, 239Pu, 241Am, and 224Cm). This method finds application in quantitative determination of alpha energy absorbed in thin membrane and, hence, the absorbed dose.
Temporal evolution of ion spectral structures during a geomagnetic storm: Observations and modeling
NASA Astrophysics Data System (ADS)
Ferradas, C.; Zhang, J.; Spence, H. E.; Kistler, L. M.; Larsen, B.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.
2016-12-01
During the last decades several missions have recorded the presence of dynamic spectral features of energetic ions in the inner magnetosphere. We present a case study of the temporal evolution of H+, He+, and O+ spectral structures throughout the geomagnetic storm of 2 October 2013. We use data from the Helium, Oxygen, Proton, and Electron (HOPE) mass spectrometer onboard Van Allen Probe A to analyze the spectral structures in the energy range of 1- 50 keV. We find that the characteristics of the ion structures follow a cyclic pattern, the observed features changing dramatically as the storm starts and then returning to its initial pre-storm state. Quiet, pre-storm times are characterized by multiple and often complex flux structures at narrow energy bands. During the storm main phase, the observed features become simple, with no nose structures or only one nose structure present in the energy-time spectrograms. As the inner magnetosphere recovers from the storm, more complex structures appear once again. Additionally, the heavy ion spectral features are generally more complex than the H+ features, with multiple noses being observed more often in the heavy ion spectra. We use a model of ion drift and losses due to charge exchange to understand the formation of the spectral features and their species dependence.
Application of laser driven fast high density plasma blocks for ion implantation
NASA Astrophysics Data System (ADS)
Sari, Amir H.; Osman, F.; Doolan, K. R.; Ghoranneviss, M.; Hora, H.; Höpfl, R.; Benstetter, G.; Hantehzadeh, M. H.
2005-10-01
The measurement of very narrow high density plasma blocks of high ion energy from targets irradiated with ps-TW laser pulses based on a new skin depth interaction process is an ideal tool for application of ion implantation in materials, especially of silicon, GaAs, or conducting polymers, for micro-electronics as well as for low cost solar cells. A further application is for ion sources in accelerators with most specifications of many orders of magnitudes advances against classical ion sources. We report on near band gap generation of defects by implantation of ions as measured by optical absorption spectra. A further connection is given for studying the particle beam transforming of n-type semiconductors into p-type and vice versa as known from sub-threshold particle beams. The advantage consists in the use of avoiding aggressive or rare chemical materials when using the beam techniques for industrial applications.
Kinetic energy budget for electroconvective flows near ion selective membranes
NASA Astrophysics Data System (ADS)
Wang, Karen; Mani, Ali
2017-11-01
Electroconvection occurs when ions are driven from a bulk fluid through an ion-selective surface. When the driving voltage is beyond a threshold, this process undergoes a hydrodynamic instability called electroconvection, which can become chaotic due to nonlinear coupling between ion-transport, fluid flow, and electrostatic forces. Electroconvection significantly enhances ion transport and plays an important role in a wide range of electrochemical applications. We investigate this phenomenon by considering a canonical geometry consisting of a symmetric binary electrolyte between an ion-selective membrane and a reservoir using 2D direct numerical simulation (DNS). Our simulations reveal that for most practical regimes, DNS of electroconvection is expensive. Thus, a plan towards development of reduced-order models is necessary to facilitate the adoption of analysis of this phenomenon in industry. Here we use DNS to analyze the kinetic energy budget to shed light into the mechanisms sustaining flow and mixing in electroconvective flows. Our analysis reveals the relative dominance of kinetic energy sources, dissipation, and transport mechanisms sustaining electroconvection at different distances from the interface and over a wide range of input parameters. Karen Wang was supported by the National Defense Science & Engineering Graduate Fellowship (NDSEG). Ali Mani was supported by the National Science Foundation Award.
Transition energies and polarizabilities of hydrogen like ions in plasma
DOE Office of Scientific and Technical Information (OSTI.GOV)
Das, Madhusmita
2012-09-15
Effect of plasma screening on various properties like transition energy, polarizability (dipole and quadrupole), etc. of hydrogen like ions is studied. The bound and free state wave functions and transition matrix elements are obtained by numerically integrating the radial Schrodinger equation for appropriate plasma potential. We have used adaptive step size controlled Runge-Kutta method to perform the numerical integration. Debye-Huckel potential is used to investigate the variation in transition lines and polarizabilities (dipole and quadrupole) with increasing plasma screening. For a strongly coupled plasma, ion sphere potential is used to show the variation in excitation energy with decreasing ion spheremore » radius. It is observed that plasma screening sets in phenomena like continuum lowering and pressure ionization, which are unique to ions in plasma. Of particular interest is the blue (red) shift in transitions conserving (non-conserving) principal quantum number. The plasma environment also affects the dipole and quadrupole polarizability of ions in a significant manner. The bound state contribution to polarizabilities decreases with increase in plasma density whereas the continuum contribution is significantly enhanced. This is a result of variation in the behavior of bound and continuum state wave functions in the presence of plasma. We have compared the results with existing theoretical and experimental data wherever present.« less
Cold Ion Outflow Modulated by the Solar Wind Energy Input and Tilt of the Geomagnetic Dipole
NASA Astrophysics Data System (ADS)
Li, Kun; Wei, Y.; André, M.; Eriksson, A.; Haaland, S.; Kronberg, E. A.; Nilsson, H.; Maes, L.; Rong, Z. J.; Wan, W. X.
2017-10-01
The solar wind energy input into the Earth's magnetosphere-ionosphere system drives ionospheric outflow, which plays an important role in both the magnetospheric dynamics and evolution of the atmosphere. However, little is known about the cold ion outflow with energies lower than a few tens of eV, as the direct measurement of cold ions is difficult because a spacecraft gains a positive electric charge due to the photoemission effect, which prevents cold ions from reaching the onboard detectors. A recent breakthrough in the measurement technique using Cluster spacecraft revealed that cold ions dominate the ion population in the magnetosphere. This new technique yields a comprehensive data set containing measurements of the velocities and densities of cold ions for the years 2001-2010. In this paper, this data set is used to analyze the cold ion outflow from the ionosphere. We found that about 0.1% of the solar wind energy input is transformed to the kinetic energy of cold ion outflow at the topside ionosphere. We also found that the geomagnetic dipole tilt can significantly affect the density of cold ion outflow, modulating the outflow rate of cold ion kinetic energy. These results give us clues to study the evolution of ionospheric outflow with changing global magnetic field and solar wind condition in the history.
A method for computing ion energy distributions for multifrequency capacitive discharges
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wu, Alan C. F.; Lieberman, M. A.; Verboncoeur, J. P.
2007-03-01
The ion energy distribution (IED) at a surface is an important parameter for processing in multiple radio frequency driven capacitive discharges. An analytical model is developed for the IED in a low pressure discharge based on a linear transfer function that relates the time-varying sheath voltage to the time-varying ion energy response at the surface. This model is in good agreement with particle-in-cell simulations over a wide range of single, dual, and triple frequency driven capacitive discharge excitations.
Enhanced tunable narrow-band THz emission from laser-modulated electron beams
DOE Office of Scientific and Technical Information (OSTI.GOV)
Xiang, D.; Stupakov, G.; /SLAC
2009-06-19
We propose and analyze a scheme to generate enhanced narrow-band terahertz (THz) radiation through down-conversion of the frequency of optical lasers using laser-modulated electron beams. In the scheme the electron beam is first energy modulated by two lasers with wave numbers k{sub 1} and k2, respectively. After passing through a dispersion section, the energy modulation is converted to density modulation. Due to the nonlinear conversion process, the beam will have density modulation at wave number k = nk{sub 1} + mk{sub 2}, where n and m are positive or negative integers. By properly choosing the parameters for the lasers andmore » dispersion section, one can generate density modulation at THz frequency in the beam using optical lasers. This density-modulated beam can be used to generate powerful narrow-band THz radiation. Since the THz radiation is in tight synchronization with the lasers, it should provide a high temporal resolution for the optical-pump THz-probe experiments. The central frequency of the THz radiation can be easily tuned by varying the wavelength of the two lasers and the energy chirp of the electron beam. The proposed scheme is in principle able to generate intense narrow-band THz radiation covering the whole THz range and offers a promising way towards the tunable intense narrow-band THz sources.« less
Solvent-coordinate free-energy landscape view of water-mediated ion-pair dissociation
NASA Astrophysics Data System (ADS)
Yonetani, Yoshiteru
2017-12-01
Water-mediated ion-pair dissociation is studied by molecular dynamics simulations of NaCl in water. Multidimensional free-energy analysis clarifies the relation between two essential solvent coordinates: the water coordination number and water-bridge formation. These two are related in a complex way. Both are necessary to describe ion-pair dissociation. The mechanism constructed with both solvent variables clearly shows the individual roles. The water coordination number is critical for starting ion-pair dissociation. Water-bridge formation is also important because it increases the likelihood of ion-pair dissociation by reducing the dissociation free-energy barrier. Additional Ca-Cl and NH4-Cl calculations show that these conclusions are unaffected by changes in the ion charge and shape. The present results will contribute to future explorations of many other molecular events such as surface water exchange and protein-ligand dissociation because the same mechanism is involved in such events.
Tessonnier, Thomas; Marcelos, Tiago; Mairani, Andrea; Brons, Stephan; Parodi, Katia
2015-01-01
In the field of radiation therapy, accurate and robust dose calculation is required. For this purpose, precise modeling of the irradiation system and reliable computational platforms are needed. At the Heidelberg Ion Therapy Center (HIT), the beamline has been already modeled in the FLUKA Monte Carlo (MC) code. However, this model was kept confidential for disclosure reasons and was not available for any external team. The main goal of this study was to create efficiently phase space (PS) files for proton and carbon ion beams, for all energies and foci available at HIT. PSs are representing the characteristics of each particle recorded (charge, mass, energy, coordinates, direction cosines, generation) at a certain position along the beam path. In order to achieve this goal, keeping a reasonable data size but maintaining the requested accuracy for the calculation, we developed a new approach of beam PS generation with the MC code FLUKA. The generated PSs were obtained using an infinitely narrow beam and recording the desired quantities after the last element of the beamline, with a discrimination of primaries or secondaries. In this way, a unique PS can be used for each energy to accommodate the different foci by combining the narrow-beam scenario with a random sampling of its theoretical Gaussian beam in vacuum. PS can also reproduce the different patterns from the delivery system, when properly combined with the beam scanning information. MC simulations using PS have been compared to simulations, including the full beamline geometry and have been found in very good agreement for several cases (depth dose distributions, lateral dose profiles), with relative dose differences below 0.5%. This approach has also been compared with measured data of ion beams with different energies and foci, resulting in a very satisfactory agreement. Hence, the proposed approach was able to fulfill the different requirements and has demonstrated its capability for application to
Kelly, Casey P.; Cramer, Christopher J.; Truhlar, Donald G.
2008-01-01
The division of thermodynamic solvation free energies of electrolytes into ionic constituents is conventionally accomplished by using the single-ion solvation free energy of one reference ion, conventionally the proton, to set the single-ion scales. Thus the determination of the free energy of solvation of the proton in various solvents is a fundamental issue of central importance in solution chemistry. In the present article, relative solvation free energies of ions and ion-solvent clusters in methanol, acetonitrile, and dimethyl sulfoxide (DMSO) have been determined using a combination of experimental and theoretical gas-phase free energies of formation, solution-phase reduction potentials and acid dissociation constants, and gas-phase clustering free energies. Applying the cluster pair approximation to differences between these relative solvation free energies leads to values of −263.5, −260.2, and −273.3 kcal/mol for the absolute solvation free energy of the proton in methanol, acetonitrile, and DMSO, respectively. The final absolute proton solvation free energies are used to assign absolute values for the normal hydrogen electrode potential and the solvation free energies of other single ions in the above solvents. PMID:17214493
NASA Technical Reports Server (NTRS)
Patterson, James D.; Li, Wei-Gang
1995-01-01
The project has evolved to that of using Green's functions to predict properties of deep defects in narrow gap materials. Deep defects are now defined as originating from short range potentials and are often located near the middle of the energy gap. They are important because they affect the lifetime of charge carriers and hence the switching time of transistors. We are now moving into the arena of predicting formation energies of deep defects. This will also allow us to make predictions about the relative concentrations of the defects that could be expected at a given temperature. The narrow gap materials mercury cadmium telluride (MCT), mercury zinc telluride (MZT), and mercury zinc selenide (MZS) are of interest to NASA because they have commercial value for infrared detecting materials, and because there is a good possibility that they can be grown better in a microgravity environment. The uniform growth of these crystals on earth is difficult because of convection (caused by solute depletion just ahead of the growing interface, and also due to thermal gradients). In general it is very difficult to grow crystals with both radial and axial homogeneity.
Narrow chaotic compound autoionizing states in atomic spectra
DOE Office of Scientific and Technical Information (OSTI.GOV)
Flambaum, V.V.; Gribakina, A.A.; Gribakin, G.F.
1996-09-01
Simultaneous excitation of several valence electrons in atoms gives rise to a dense spectrum of compound autoionizing states (AIS). These states are almost chaotic superpositions of large numbers of many-electron basis states built of single-electron orbitals. The mean level spacing {ital D} between such states is very small (e.g., {ital D}{lt}0.01 eV for the numerical example of {ital J}{sup {pi}}=4{sup {minus}} states of Ce just above the ionization threshold). The autoionization widths of these states estimated by perturbations, {gamma}=2{pi}{vert_bar}{ital W}{vert_bar}{sup 2}, where {ital W} is the Coulomb matrix element coupling the AIS to the continuum, are also small, but comparablemore » with {ital D} in magnitude: {gamma}{approximately}{ital D}. Hence the nonperturbative interaction of AIS with each other via the continuum is very essential. It suppresses greatly the widths of the autoionizing resonances ({Gamma}{approx_equal}{ital D}{sup 2}/3{gamma}{lt}{ital D}), and leads to the emergence of a {open_quote}{open_quote}collective{close_quote}{close_quote} doorway state which accumulates a large share of the total width. This state is in essence a modified single-particle continuum decoupled from the resonances due to its large width. Narrow compound AIS should be a common feature of atomic spectra at energies sufficient for excitation of several electrons above the ground-state configuration. The narrow resonances can be observed as peaks in the photoabsorption, or, in electron-ion scattering, as Fano-type profiles on the background provided by the wide doorway-state resonance. It is also shown that the statistics of electromagnetic and autoionization amplitudes involving compound states are close to Gaussian. {copyright} {ital 1996 The American Physical Society.}« less
High-flux source of low-energy neutral beams using reflection of ions from metals
NASA Technical Reports Server (NTRS)
Cuthbertson, John W.; Motley, Robert W.; Langer, William D.
1992-01-01
Reflection of low-energy ions from surfaces can be applied as a method of producing high-flux beams of low-energy neutral particles, and is an important effect in several areas of plasma technology, such as in the edge region of fusion devices. We have developed a beam source based on acceleration and reflection of ions from a magnetically confined coaxial RF plasma source. The beam provides a large enough flux to allow the energy distribution of the reflected neutrals to be measured despite the inefficiency of detection, by means of an electrostatic cylindrical mirror analyzer coupled with a quadrupole mass spectrometer. Energy distributions have been measured for oxygen, nitrogen, and inert gas ions incident with from 15 to 70 eV reflected from amorphous metal surfaces of several compositions. For ions of lighter atomic mass than the reflecting metal, reflected beams have peaked energy distributions; beams with the peak at 4-32 eV have been measured. The energy and mass dependences of the energy distributions as well as measurements of absolute flux, and angular distribution and divergence are reported. Applications of the neutral beams produced are described.
NASA Technical Reports Server (NTRS)
Foster, John E.; Patterson, Michael J.
2003-01-01
The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 10 Angstroms) has been documented in the literature. As part of an ongoing effort to uncover the underlying physics of the formation of these ions, ion efflux from a high current hollow cathode operating in an ion thruster discharge chamber was investigated. Using a spherical sector electrostatic energy analyzer located downstream of the discharge cathode, the ion energy distribution over a 0 to 60 eV energy range was measured. The sensitivity of the ion energy distribution function to zenith angle was also assessed at 3 different positions: 0, 15, and 25 degrees. The measurements suggest that the majority of the ion current at the measuring point falls into the analyzer with an energy approximately equal to the discharge voltage. The ion distribution, however, was found to be quite broad. The high energy tail of the distribution function tended to grow with increasing discharge current. Sensitivity of the profiles to flow rate at fixed discharge current was also investigated. A simple model is presented that provides a potential mechanism for the production of ions with energies above the discharge voltage.
Precise measurements of energy loss straggling for swift heavy ions in polymers
NASA Astrophysics Data System (ADS)
Rani, Bindu; Neetu; Sharma, Kalpana; Diwan, P. K.; Kumar, Shyam
2016-11-01
The energy loss straggling measurements for heavy ions with Z = 3-22 (∼0.2-2.5 MeV/u) in PEN (C7H5O2) and PET (C10H8O4) polymers have been carried out utilizing the swift heavy ion beam facility from 15UD Pelletron accelerator at Inter University Accelerator Centre (IUAC), New Delhi, India. The recorded spectra are analyzed in such a way that the Straggling associated with energy loss process could be measured in a systematic manner at any selected value of energy, in terms of per unit thickness of the absorber, at any desired energy intervals. The measured values have been compared with the calculated values obtained from the most commonly used Bethe-Livingston formulations applicable for collisional straggling. The results are tried to be understood in terms of the effective charge on the impinging ion within the absorber. Some interesting trends are observed.
Low Energy Sputtering Experiments for Ion Engine Lifetime Assessment
NASA Technical Reports Server (NTRS)
Duchemin Olivier B.; Polk, James E.
1999-01-01
The sputtering yield of molybdenum under xenon ion bombardment was measured using a Quartz Crystal Microbalance. The measurements were made for ion kinetic energies in the range 100-1keV on molybdenum films deposited by magnetron sputtering in conditions optimized to reproduce or approach bulk-like properties. SEM micrographs for different anode bias voltages during the deposition are compared, and four different methods were implemented to estimate the density of the molybdenum films. A careful discussion of the Quartz Crystal Microbalance is proposed and it is shown that this method can be used to measure mass changes that are distributed unevenly on the crystal electrode surface, if an analytical expression is known for the differential mass-sensitivity of the crystal and the erosion profile. Finally, results are presented that are in good agreement with previously published data, and it is concluded that this method holds the promise of enabling sputtering yield measurements at energies closer to the threshold energy in the very short term.
Energy & mass-charge distribution peculiarities of ion emitted from penning source
NASA Astrophysics Data System (ADS)
Mamedov, N. V.; Kolodko, D. V.; Sorokin, I. A.; Kanshin, I. A.; Sinelnikov, D. N.
2017-05-01
The optimization of hydrogen Penning sources used, in particular, in plasma chemical processing of materials and DLC deposition, is still very important. Investigations of mass-charge composition of these ion source emitted beams are particular relevant for miniature linear accelerators (neutron flux generators) nowadays. The Penning ion source energy and mass-charge ion distributions are presented. The relation between the discharge current abrupt jumps with increasing plasma density in the discharge center and increasing potential whipping (up to 50% of the anode voltage) is shown. Also the energy spectra in the discharge different modes as the pressure and anode potential functions are presented. It has been revealed that the atomic hydrogen ion concentration is about 5-10%, and it weakly depends on the pressure and the discharge current (in the investigated range from 1 to 10 mTorr and from 50 to 1000 μA) and increases with the anode voltage (up 1 to 3,5 kV).
NASA Astrophysics Data System (ADS)
Watanabe, Noboru; Hirayama, Tsukasa; Yamada, So; Takahashi, Masahiko
2018-04-01
We report details of an electron-ion coincidence apparatus, which has been developed for molecular-frame electron energy loss spectroscopy studies. The apparatus is mainly composed of a pulsed electron gun, an energy-dispersive electron spectrometer, and an ion momentum imaging spectrometer. Molecular-orientation dependence of the high-energy electron scattering cross section can be examined by conducting measurements of vector correlation between the momenta of the scattered electron and fragment ion. Background due to false coincidences is significantly reduced by introducing a pulsed electron beam and pulsing scheme of ion extraction. The experimental setup has been tested by measuring the inner-shell excitation of N2 at an incident electron energy of 1.5 keV and a scattering angle of 10.2°.
A coupled effect of nuclear and electronic energy loss on ion irradiation damage in lithium niobate
Liu, Peng; Zhang, Yanwen; Xue, Haizhou; ...
2016-01-09
Understanding irradiation effects induced by elastic energy loss to atomic nuclei and inelastic energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO 3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low electronic energy loss is shown to induce observable damage that increases with ion fluence. For the same electronic energy loss,more » the velocity of the incident ion could affect the energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high electronic energy loss in pre-damaged LiNbO 3 has been observed. The result indicates that pre-existing damage induced from nuclear energy loss interacts synergistically with inelastic electronic energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by electronic energy loss. As a result, this synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense electronic energy deposition along high-energy ion trajectory.« less
Trajectory analysis of low-energy and hyperthermal ions scattered from Cu(110)
DOE Office of Scientific and Technical Information (OSTI.GOV)
McEachern, R. L.; Goodstein, D. M.; Cooper, B. H.
1989-05-15
We have investigated the trajectories of Na/sup +/ ions scattered from the Cu(110) surface in the <1/bar 1/0> and <001> azimuths for a range of incident energies from 56 eV to 4 keV. Our goal is to explain the trends observed in the energy spectra and determine what types of trajectories contribute to these spectra. Using the computer program SAFARI, we have performed simulations with trajectory analyses for 100-, 200-, and 400-eV scattering. We show results from the 100-eV simulations in both azimuths and compare them with the experimental data. The simulated energy spectra are in excellent agreement with themore » data. Ion trajectories and impact parameter plots from the simulations are used to determine the relative importance of different types of ion--surface-atom collisions. The simulations have shown that the striking differences observed in comparing the <1/bar 1/0> and <001> spectra are mostly due to ions which scatter from second-layer atoms. This system exhibits strong focusing onto the second-layer atoms by the first-layer rows, and the focusing is very sensitive to the spacing between the rows. At the lower beam energies, scattering from the second layer dominates the measured spectra.« less
Narrow-linewidth Q-switched random distributed feedback fiber laser.
Xu, Jiangming; Ye, Jun; Xiao, Hu; Leng, Jinyong; Wu, Jian; Zhang, Hanwei; Zhou, Pu
2016-08-22
A narrow-linewidth Q-switched random fiber laser (RFL) based on a half-opened cavity, which is realized by narrow-linewidth fiber Bragg grating (FBG) and a section of 3 km passive fiber, has been proposed and experimentally investigated. The narrow-linewidth lasing is generated by the spectral filtering of three FBGs with linewidth of 1.21 nm, 0.56 nm, and 0.12 nm, respectively. The Q switching of the distributed cavity is achieved by placing an acousto-optical modulator (AOM) between the FBG and the passive fiber. The maximal output powers of the narrow-linewidth RFLs with the three different FBGs are 0.54 W, 0.27 W, and 0.08 W, respectively. Furthermore, the repetition rates of the output pulses are 500 kHz, and the pulse durations are about 500 ns. The corresponding pulse energies are about 1.08 μJ, 0.54 μJ, and 0.16 μJ, accordingly. The linewidth of FBG can influence the output characteristics in full scale. The narrower the FBG, the higher the pump threshold; the lower the output power at the same pump level, the more serious the linewidth broadening; and thus the higher the proportion of the CW-ground exists in the output pulse trains. Thanks to the assistance of the band-pass filter (BPF), the proportion of the CW-ground of narrow-linewidth Q-switched RFL under the relative high-pump-low-output condition can be reduced effectively. The experimental results indicate that it is challenging to demonstrate a narrow-linewidth Q-switched RFL with high quality output. But further power scaling and linewidth narrowing is possible in the case of operating parameters, optimization efforts, and a more powerful pump source. To the best of our knowledge, this is the first demonstration of narrow-linewidth generation in a Q-switched RFL.
Cryogenic Detectors (Narrow Field Instruments)
NASA Astrophysics Data System (ADS)
Hoevers, H.; Verhoeve, P.
Two cryogenic imaging spectrometer arrays are currently considered as focal plane instruments for XEUS. The narrow field imager 1 (NFI 1) will cover the energy range from 0.05 to 3 keV with an energy resolution of 2 eV, or better, at 500 eV. A second narrow field imager (NFI 2) covers the energy range from 1 to 15 keV with an energy resolution of 2 eV (at 1 keV) and 5 eV (at 7 keV), creating some overlap with part of the NFI 1 energy window. Both narrow field imagers have a 0.5 arcmin field of view. Their imaging capabilities are matched to the XEUS optics of 2 to 5 arcsec leading to 1 arcsec pixels. The detector arrays will be cooled by a closed cycle system comprising a mechanical cooler with a base temperature of 2.5 K and either a low temperature 3He sorption pump providing the very low temperature stage and/or an Adiabatic Demagnetization Refrigerator (ADR). The ADR cooler is explicitly needed to cool the NFI 2 array. The narrow field imager 1} Currently a 48 times 48 element array of superconducting tunnel junctions (STJ) is envisaged. Its operating temperature is in the range between 30 and 350 mK. Small, single Ta STJs (20-50 mum on a side) have shown 3.5 eV (FWHM) resolution at E = 525 eV and small arrays have been successfully demonstrated (6 times 6 pixels), or are currently tested (10 times 12 pixels). Alternatively, a prototype Distributed Read-Out Imaging Device (DROID), consisting of a linear superconducting Ta absorber of 20 times 100 mum2, including a 20 times 20 mum STJ for readout at either end, has shown a measured energy resolution of 2.4 eV (FWHM) at E = 500 eV. Simulations involving the diffusion properties as well as loss and tunnel rates have shown that the performance can be further improved by slight modifications in the geometry, and that the size of the DROIDS can be increased to 0.5-1.0 mm without loss in energy resolution. The relatively large areas and good energy resolution compared to single STJs make DROIDS good candidates for the
NASA Astrophysics Data System (ADS)
Tanaka, Koichi; Han, Liang; Zhou, Xue; Anders, André
2015-08-01
Charge-state-resolved ion energy-time distributions of pulsed Cu arc plasma were obtained by using direct (time-dependent) acquisition of the ion detection signal from a commercial ion mass-per-charge and energy-per-charge analyzer. We find a shift of energies of Cu2+, Cu3+ and Cu4+ ions to lower values during the first few hundred microseconds after arc ignition, which is evidence for particle collisions in the plasma. The generation of Cu+ ions in the later part of the pulse, measured by the increase of Cu+ signal intensity and an associated slight reduction of the mean charge state, points to charge exchange reactions between ions and neutrals. At the very beginning of the pulse, when the plasma expands into vacuum and the plasma potential strongly fluctuates, ions with much higher energy (over 200 eV) are observed. Early in the pulse, the ion energies observed are approximately proportional to the ion charge state, and we conclude that the acceleration mechanism is primarily based on acceleration in an electric field. This field is directed away from the cathode, indicative of a potential hump. Measurements by a floating probe suggest that potential structures travel, and ions moving in the traveling field can gain high energies up to a few hundred electron-volts. Later in the pulse, the approximate proportionality is lost, which is related to increased smearing out of different energies due to collisions with neutrals, and/or to a change of the acceleration character from electrostatic to ‘gas-dynamic’, i.e. dominated by pressure gradient.
NASA Astrophysics Data System (ADS)
Yu, Chen; Zhixin, Lin; Zuyao, Zou; Feng, Zhang; Duo, Liu; Xianghuai, Liu; Jianzhong, Tang; Weimin, Zhu; Bo, Huang
1998-05-01
Conidia of Streptomyces erythreus, an industrial microbe, were implanted by nitrogen ions with energy of 40-60 keV and fluence from 1 × 10 11 to 5 × 10 14 ions/cm 2. The logarithm value of survival fraction had good linear relationship with the logarithm value of fluence. Some mutants with a high yield of erythromycin were induced by ion implantation. The yield increment was correlated with the implantation fluence. Compared with the mutation results induced by ultraviolet rays, mutation effects of ion implantation were obvious having higher increasing erythromycin potency and wider mutation spectrum. The spores of Bacillus subtilis were implanted by arsenic ions with energy of 100 keV. The distribution of implanted ions was measured by Rutherford Backscattering Spectrometry (RBS) and calculated in theory. The mechanism of mutation induced by ion implantation was discussed.
Calibration of BAS-TR image plate response to high energy (3-300 MeV) carbon ions
NASA Astrophysics Data System (ADS)
Doria, D.; Kar, S.; Ahmed, H.; Alejo, A.; Fernandez, J.; Cerchez, M.; Gray, R. J.; Hanton, F.; MacLellan, D. A.; McKenna, P.; Najmudin, Z.; Neely, D.; Romagnani, L.; Ruiz, J. A.; Sarri, G.; Scullion, C.; Streeter, M.; Swantusch, M.; Willi, O.; Zepf, M.; Borghesi, M.
2015-12-01
The paper presents the calibration of Fuji BAS-TR image plate (IP) response to high energy carbon ions of different charge states by employing an intense laser-driven ion source, which allowed access to carbon energies up to 270 MeV. The calibration method consists of employing a Thomson parabola spectrometer to separate and spectrally resolve different ion species, and a slotted CR-39 solid state detector overlayed onto an image plate for an absolute calibration of the IP signal. An empirical response function was obtained which can be reasonably extrapolated to higher ion energies. The experimental data also show that the IP response is independent of ion charge states.
Calibration of BAS-TR image plate response to high energy (3-300 MeV) carbon ions.
Doria, D; Kar, S; Ahmed, H; Alejo, A; Fernandez, J; Cerchez, M; Gray, R J; Hanton, F; MacLellan, D A; McKenna, P; Najmudin, Z; Neely, D; Romagnani, L; Ruiz, J A; Sarri, G; Scullion, C; Streeter, M; Swantusch, M; Willi, O; Zepf, M; Borghesi, M
2015-12-01
The paper presents the calibration of Fuji BAS-TR image plate (IP) response to high energy carbon ions of different charge states by employing an intense laser-driven ion source, which allowed access to carbon energies up to 270 MeV. The calibration method consists of employing a Thomson parabola spectrometer to separate and spectrally resolve different ion species, and a slotted CR-39 solid state detector overlayed onto an image plate for an absolute calibration of the IP signal. An empirical response function was obtained which can be reasonably extrapolated to higher ion energies. The experimental data also show that the IP response is independent of ion charge states.
Energy conversion through mass loading of escaping ionospheric ions for different Kp values
NASA Astrophysics Data System (ADS)
Yamauchi, Masatoshi; Slapak, Rikard
2018-01-01
By conserving momentum during the mixing of fast solar wind flow and slow planetary ion flow in an inelastic way, mass loading converts kinetic energy to other forms - e.g. first to electrical energy through charge separation and then to thermal energy (randomness) through gyromotion of the newly born cold ions for the comet and Mars cases. Here, we consider the Earth's exterior cusp and plasma mantle, where the ionospheric origin escaping ions with finite temperatures are loaded into the decelerated solar wind flow. Due to direct connectivity to the ionosphere through the geomagnetic field, a large part of this electrical energy is consumed to maintain field-aligned currents (FACs) toward the ionosphere, in a similar manner as the solar wind-driven ionospheric convection in the open geomagnetic field region. We show that the energy extraction rate by the mass loading of escaping ions (ΔK) is sufficient to explain the cusp FACs, and that ΔK depends only on the solar wind velocity accessing the mass-loading region (usw) and the total mass flux of the escaping ions into this region (mloadFload), as ΔK ˜ -mloadFloadu2sw/4. The expected distribution of the separated charges by this process also predicts the observed flowing directions of the cusp FACs for different interplanetary magnetic field (IMF) orientations if we include the deflection of the solar wind flow directions in the exterior cusp. Using empirical relations of u0 ∝ Kp + 1.2 and Fload ∝ exp(0.45Kp) for Kp = 1-7, where u0 is the solar wind velocity upstream of the bow shock, ΔK becomes a simple function of Kp as log10(ΔK) = 0.2 ṡ Kp + 2 ṡ log10(Kp + 1.2) + constant. The major contribution of this nearly linear increase is the Fload term, i.e. positive feedback between the increase of ion escaping rate Fload through the increased energy consumption in the ionosphere for high Kp, and subsequent extraction of more kinetic energy ΔK from the solar wind to the current system by the increased
Low-energy ion distribution functions on a magnetically quiet day at geostationary altitude /L = 7/
NASA Technical Reports Server (NTRS)
Singh, N.; Raitt, W. J.; Yasuhara, F.
1982-01-01
Ion energy and pitch angle distribution functions are examined for a magnetically quiet day using averaged data from ATS 6. For both field-aligned and perpendicular fluxes, the populations have a mixture of characteristic energies, and the distribution functions can be fairly well approximated by Maxwellian distributions over three different energy bands in the range 3-600 eV. Pitch angle distributions varying with local time, and energy distributions are used to compute total ion density. Pitch angle scattering mechanisms responsible for the observed transformation of pitch angle distribution are examined, and it is found that a magnetic noise of a certain power spectral density belonging to the electromagnetic ion cyclotron mode near the ion cyclotron frequency can be effective in trapping the field aligned fluxes by pitch angle scattering.
CMOS active pixel sensors response to low energy light ions
NASA Astrophysics Data System (ADS)
Spiriti, E.; Finck, Ch.; Baudot, J.; Divay, C.; Juliani, D.; Labalme, M.; Rousseau, M.; Salvador, S.; Vanstalle, M.; Agodi, C.; Cuttone, G.; De Napoli, M.; Romano, F.
2017-12-01
Recently CMOS active pixel sensors have been used in Hadrontherapy ions fragmentation cross section measurements. Their main goal is to reconstruct tracks generated by the non interacting primary ions or by the produced fragments. In this framework the sensors, unexpectedly, demonstrated the possibility to obtain also some informations that could contribute to the ion type identification. The present analysis shows a clear dependency in charge and number of pixels per cluster (pixels with a collected amount of charge above a given threshold) with both fragment atomic number Z and energy loss in the sensor. This information, in the FIRST (F ragmentation of I ons R elevant for S pace and T herapy) experiment, has been used in the overall particle identification analysis algorithm. The aim of this paper is to present the data analysis and the obtained results. An empirical model was developed, in this paper, that reproduce the cluster size as function of the deposited energy in the sensor.
Review of light-ion driver development for inertial fusion energy
NASA Astrophysics Data System (ADS)
Bluhm, H.; Hoppé, P.
2001-05-01
The concept of a light ion beam driver for Inertial Fusion Energy (IFE) is based on multi-terawatt, multi-megavolt pulsed power generators, two-stage ion acceleration and charge neutralised transport. In this paper we discuss the present status for each of these components and identify the main issues for research. Only modest extrapolations from presently available technologies seem necessary for the high voltage pulse generator. The greatest challenge of this approach is the accelerator, which will consist of two stages, the injector and the post-accelerator. Large progress has been made in understanding the physical phenomena occurring in the injector gap. This progress has become possible by new sophisticated diagnostics that allowed detailed temporally and spatially resolved measurements of field and particle densities in the acceleration gap and by relativistic fully electromagnetic PIC-simulation tools, that stimulated analytic models. The conclusions drawn from these studies, namely limiting the ion current density to small enhancements to reduce the beam divergence need still to be verified experimentally. Systematic experimental research on post-acceleration at high power and voltage must aim at a complete understanding of instabilities coupling from the injector to the post-accelerator and at limiting voltages and barriers for the extraction of unwanted ions from plasmas at the injection side. Ultimately the light ion approach requires rep-rateable large area ion sources with ion masses greater than 1 and particle energies around 30 MeV. Although different cleaning protocols were able to reduce the amount of parasitic ions in the Li beam from a LiF field emission source the achievements are still insufficient. A field of common interest between light and heavy ion beam driven fusion is beam transport from the accelerator to the target. Supposedly the most favourable concept for both approaches is self-pinched transport. Experimental evidence for self
Visualization and analysis of pulsed ion beam energy density profile with infrared imaging
NASA Astrophysics Data System (ADS)
Isakova, Y. I.; Pushkarev, A. I.
2018-03-01
Infrared imaging technique was used as a surface temperature-mapping tool to characterize the energy density distribution of intense pulsed ion beams on a thin metal target. The technique enables the measuring of the total ion beam energy and the energy density distribution along the cross section and allows one to optimize the operation of an ion diode and control target irradiation mode. The diagnostics was tested on the TEMP-4M accelerator at TPU, Tomsk, Russia and on the TEMP-6 accelerator at DUT, Dalian, China. The diagnostics was applied in studies of the dynamics of the target cooling in vacuum after irradiation and in the experiments with target ablation. Errors caused by the target ablation and target cooling during measurements have been analyzed. For Fluke Ti10 and Fluke Ti400 infrared cameras, the technique can achieve surface energy density sensitivity of 0.05 J/cm2 and spatial resolution of 1-2 mm. The thermal imaging diagnostics does not require expensive consumed materials. The measurement time does not exceed 0.1 s; therefore, this diagnostics can be used for the prompt evaluation of the energy density distribution of a pulsed ion beam and during automation of the irradiation process.
NASA Astrophysics Data System (ADS)
Urbain, Xavier
2016-09-01
While the measurement of total absolute cross sections remains challenging, the insight provided by differential cross sections and branching ratios is invaluable to assess the quality of theoretical predictions. Satisfactory agreement at the latter level gives better confidence in the proper identification of the reaction mechanism and key parameters. The three dimensional imaging of molecular dissociation, and more generally, the determination of all momentum vectors of the reaction products, gives direct access to the differential quantities of interest. For the prototype reaction of a proton colliding with H2, the secondary H2+current may be recorded to provide the total charge transfer yield. The dissociative charge transfer of the product ions with alkali targets leaves a characteristic signature in the total kinetic energy imparted to the H fragments. Its measurement is readily achieved by coincident detection on position sensitive detectors. This allows us to extract vibrational populations as a function of collision energy. A resonant enhancement of the charge transfer around 45 eV/amu is observed, that leaves the molecular ion in its vibrational ground state. Those observations are supported by state-of-the-art calculations. We have similarly explored the ionization of molecular oxygen by proton and alpha particle impact, at velocities characteristic of the solar wind. A somewhat more involved vibrational analysis of the O2+cations indicates a Franck-Condon like vibrational population of the ground electronic state from 50 eV to 10 keV, unlikely to modify the branching ratios of dissociative recombination, itself responsible for airglow emissions. More interestingly, a significant population of the 4Πu excited state is measured at velocities typical of the fast solar wind. Finally, we shall address the implementation of three dimensional imaging in merged ion-ion beam studies. Mutual neutralization involving anions and cations is a very efficient process
NASA Astrophysics Data System (ADS)
Yayathi, Sandeep; Walker, William; Doughty, Daniel; Ardebili, Haleh
2016-10-01
Lithium ion (Li-ion) batteries provide low mass and energy dense solutions necessary for space exploration, but thermal related safety concerns impede the utilization of Li-ion technology for human applications. Experimental characterization of thermal runaway energy release with accelerated rate calorimetry supports safer thermal management systems. 'Standard' accelerated rate calorimetry setup provides means to measure the addition of energy exhibited through the body of a Li-ion cell. This study considers the total energy generated during thermal runaway as distributions between cell body and hot gases via inclusion of a unique secondary enclosure inside the calorimeter; this closed system not only contains the cell body and gaseous species, but also captures energy release associated with rapid heat transfer to the system unobserved by measurements taken on the cell body. Experiments include Boston Power Swing 5300, Samsung 18650-26F and MoliCel 18650-J Li-ion cells at varied states-of-charge. An inverse relationship between state-of-charge and onset temperature is observed. Energy contained in the cell body and gaseous species are successfully characterized; gaseous energy is minimal. Significant additional energy is measured with the heating of the secondary enclosure. Improved calorimeter apparatus including a secondary enclosure provides essential capability to measuring total energy release distributions during thermal runaway.
Kinetic energy distribution of multiply charged ions in Coulomb explosion of Xe clusters.
Heidenreich, Andreas; Jortner, Joshua
2011-02-21
We report on the calculations of kinetic energy distribution (KED) functions of multiply charged, high-energy ions in Coulomb explosion (CE) of an assembly of elemental Xe(n) clusters (average size (n) = 200-2171) driven by ultra-intense, near-infrared, Gaussian laser fields (peak intensities 10(15) - 4 × 10(16) W cm(-2), pulse lengths 65-230 fs). In this cluster size and pulse parameter domain, outer ionization is incomplete∕vertical, incomplete∕nonvertical, or complete∕nonvertical, with CE occurring in the presence of nanoplasma electrons. The KEDs were obtained from double averaging of single-trajectory molecular dynamics simulation ion kinetic energies. The KEDs were doubly averaged over a log-normal cluster size distribution and over the laser intensity distribution of a spatial Gaussian beam, which constitutes either a two-dimensional (2D) or a three-dimensional (3D) profile, with the 3D profile (when the cluster beam radius is larger than the Rayleigh length) usually being experimentally realized. The general features of the doubly averaged KEDs manifest the smearing out of the structure corresponding to the distribution of ion charges, a marked increase of the KEDs at very low energies due to the contribution from the persistent nanoplasma, a distortion of the KEDs and of the average energies toward lower energy values, and the appearance of long low-intensity high-energy tails caused by the admixture of contributions from large clusters by size averaging. The doubly averaged simulation results account reasonably well (within 30%) for the experimental data for the cluster-size dependence of the CE energetics and for its dependence on the laser pulse parameters, as well as for the anisotropy in the angular distribution of the energies of the Xe(q+) ions. Possible applications of this computational study include a control of the ion kinetic energies by the choice of the laser intensity profile (2D∕3D) in the laser-cluster interaction volume.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhu, Zihua; Nachimuthu, Ponnusamy; Lea, Alan S.
2009-10-15
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiling of sucrose thin films were investigated using 10 keV C60+, 20 keV C602+, 30 keV C603+, 250 eV, 500 eV and 1000 eV Cs+ and O2+ as sputtering ions. With C60n+ ions, the molecular ion signal initially decreases, and reaches a steady-state that is about 38-51% of its original intensity, depending on the energy of the C60n+ ions. On the contrary, with Cs+ and O2+ sputtering, molecular ion signals decrease quickly to the noise level, even using low energy (250 eV) sputtering ions. In addition, the sucrose/Si interface by C60+ sputtering ismore » much narrower than that of Cs+ and O2+ sputtering. To understand the mechanisms of sputtering-induced damage by these ions, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize the bottoms of these sputter craters. XPS data show very little chemical change in the C60+ sputter crater, while considerable amorphous carbon was found in the O2+ and Cs+ sputter craters, indicating extensive decomposition of the sucrose molecules. AFM images show a very flat bottom in the C60+ sputter crater, while the Cs+ and O2+ sputter crater bottoms are significantly rougher than that of the C60+ sputter crater. Based on above data, we developed a simple model to explain different damage mechanisms during sputtering process.« less
MMS Observation of Inverse Energy Dispersion in Shock Drift Acceleration Ions
NASA Astrophysics Data System (ADS)
Lee, S. H.; Sibeck, D. G.; Hwang, K. J.; Wang, Y.; Silveira, M. D.; Mauk, B.; Cohen, I. J.; Chu, C. S.; Mason, G. M.; Gold, R. E.; Burch, J. L.; Giles, B. L.; Torbert, R. B.; Russell, C. T.; Wei, H.
2016-12-01
The Energetic Particle Detector (EPD) on the Magnetospheric Multiscale (MMS) spacecraft observed bursts of energetic ions (50 keV-1000 keV) both in the foreshock and in the magnetosheath near the bow shock on December 6, 2015. Three species (protons, helium, and oxygen) exhibit inverse energy dispersions. Angular distributions for all three species indicate acceleration at the perpendicular bow shock. Acceleration that energizes the seed solar population by a factor of 2 and 4 is required for the protons and helium ions, respectively. The energy of the ions increases with θBn (the angle between the IMF and the local shock normal) since the induced electric field that energizes the charged particles increases as θBn increases towards 90°. We compare events upstream and downstream from the bow shock. We compare the MMS observations with those of the solar wind seed populations by the Ultra Low Energy Isotope Spectrometer (ULEIS) instrument on the Advanced Composition Explorer (ACE) mission and by the WIND 3-D Plamsa and Energetic Particle Experiment.
Comparison of magnetosonic wave and water group ion energy densities at Comet Giacobini-Zinner
NASA Technical Reports Server (NTRS)
Staines, K.; Balogh, A.; Cowley, S. W. H.; Forster, P. M. De F.; Hynds, R. J.; Yates, T. S.; Sanderson, T. R.; Wenzel, K.-P.; Tsurutani, B. T.
1991-01-01
Measurements of the Comet Giacobini-Zinner (GZ) are presented to determine to what extent wave-particle scattering redistributed the initial pick-up energy of the ion population. Also examined is the difference between the ion thermal energy and the energy in the magnetic fields of the waves. In spite of uncertainty of about a factor of 2 noted in the pick-up and mass-loaded regions, it is shown that less than approximately 50 percent of the pick-up energy is converted into wave magnetic energy in the inbound pick-up region.
Quasi-Solid-State Sodium-Ion Full Battery with High-Power/Energy Densities.
Guo, Jin-Zhi; Yang, Ai-Bo; Gu, Zhen-Yi; Wu, Xing-Long; Pang, Wei-Lin; Ning, Qiu-Li; Li, Wen-Hao; Zhang, Jing-Ping; Su, Zhong-Min
2018-05-30
Developing a high-performance, low-cost, and safer rechargeable battery is a primary challenge in next-generation electrochemical energy storage. In this work, a quasi-solid-state (QSS) sodium-ion full battery (SIFB) is designed and fabricated. Hard carbon cloth derived from cotton cloth and Na 3 V 2 (PO 4 ) 2 O 2 F (NVPOF) are employed as the anode and the cathode, respectively, and a sodium ion-conducting gel-polymer membrane is used as both the QSS electrolyte and separator, accomplishing the high energy and power densities in the QSS sodium-ion batteries. The energy density can reach 460 W h kg -1 according to the mass of the cathode materials. Moreover, the fabricated QSS SIFB also exhibits an excellent rate performance (e.g., about 78.1 mA h g -1 specific capacity at 10 C) and a superior cycle performance (e.g., ∼90% capacity retention after 500 cycles at 10 C). These results show that the developed QSS SIFB is a hopeful candidate for large-scale energy storage.
The stopping powers and energy straggling of heavy ions in polymer foils
NASA Astrophysics Data System (ADS)
Mikšová, R.; Macková, A.; Malinský, P.; Hnatowicz, V.; Slepička, P.
2014-07-01
The stopping power and energy straggling of 7Li, 12C and 16O ions in thin poly(etheretherketone) (PEEK), polyethylene terephthalate (PET) and polycarbonate (PC) foils were measured in the incident beam energy range of 9.4-11.8 MeV using an indirect transmission method. Ions scattered from a thin gold target at an angle of 150° were registered by a partially depleted PIPS detector, partly shielded with a polymer foil placed in front of the detector. Therefore, the signals from both direct and slowed down ions were visible in the same energy spectrum, which was evaluated by the ITAP code, developed at our laboratory. The ITAP code was employed to perform a Gaussian-fitting procedure to provide a complete analysis of each measured spectrum. The measured stopping powers were compared with the predictions obtained from the SRIM-2008 and MSTAR codes and with previous experimental data. The energy straggling data were compared with those calculated by using Bohr's, Lindhard-Scharff and Bethe-Livingston theories.
The stopping power and energy straggling of the energetic C and O ions in polyimide
NASA Astrophysics Data System (ADS)
Mikšová, R.; Macková, A.; Slepička, P.
2016-03-01
The stopping power and energy straggling of 12Cn+ and 16On+ heavy ions in the energy range 5.3-8.0 MeV in 8 μm thick polyimide (PI) foil were measured by means of an indirect transmission method using a half-covered a PIPS detector. Ions scattered from thin gold layer, under the scattering angle 150° were detected and the spectrum of ions penetrating the PI foil and without foil was recorded. The values of the experimentally determined stopping powers were compared to the calculated data by SRIM-2013 and MSTAR codes. Measured data were in good agreement with data calculated by SRIM-2013, especially for C ions was observed better agreement than for O ions. The energy straggling was determined and compared to those calculated by using Bohr's, Bethe-Livingston and Yang models. The measured energy straggling values in the PI foil was corrected for foil roughness and thickness inhomogeneity determined from AFM. Bethe-Livingston predicting formula has been modified to make it appropriate for thicker targets. The energy straggling determined in our experiment was obtained higher than Bohr's predicted value; the predictions by Yang are in good agreement with our experiment. Bethe-Livingston formulation of the energy straggling shows better agreement with the experimental data after the modified formula implementation which assumes that the thick target was consisted to be composed of n-number of thin layers. Influence of the charge-exchange phenomena to the energy straggling of C and O ions in PI was discussed.
Analyzing system safety in lithium-ion grid energy storage
Rosewater, David; Williams, Adam
2015-10-08
As grid energy storage systems become more complex, it grows more di cult to design them for safe operation. This paper first reviews the properties of lithium-ion batteries that can produce hazards in grid scale systems. Then the conventional safety engineering technique Probabilistic Risk Assessment (PRA) is reviewed to identify its limitations in complex systems. To address this gap, new research is presented on the application of Systems-Theoretic Process Analysis (STPA) to a lithium-ion battery based grid energy storage system. STPA is anticipated to ll the gaps recognized in PRA for designing complex systems and hence be more e ectivemore » or less costly to use during safety engineering. It was observed that STPA is able to capture causal scenarios for accidents not identified using PRA. Additionally, STPA enabled a more rational assessment of uncertainty (all that is not known) thereby promoting a healthy skepticism of design assumptions. Lastly, we conclude that STPA may indeed be more cost effective than PRA for safety engineering in lithium-ion battery systems. However, further research is needed to determine if this approach actually reduces safety engineering costs in development, or improves industry safety standards.« less
Analyzing system safety in lithium-ion grid energy storage
NASA Astrophysics Data System (ADS)
Rosewater, David; Williams, Adam
2015-12-01
As grid energy storage systems become more complex, it grows more difficult to design them for safe operation. This paper first reviews the properties of lithium-ion batteries that can produce hazards in grid scale systems. Then the conventional safety engineering technique Probabilistic Risk Assessment (PRA) is reviewed to identify its limitations in complex systems. To address this gap, new research is presented on the application of Systems-Theoretic Process Analysis (STPA) to a lithium-ion battery based grid energy storage system. STPA is anticipated to fill the gaps recognized in PRA for designing complex systems and hence be more effective or less costly to use during safety engineering. It was observed that STPA is able to capture causal scenarios for accidents not identified using PRA. Additionally, STPA enabled a more rational assessment of uncertainty (all that is not known) thereby promoting a healthy skepticism of design assumptions. We conclude that STPA may indeed be more cost effective than PRA for safety engineering in lithium-ion battery systems. However, further research is needed to determine if this approach actually reduces safety engineering costs in development, or improves industry safety standards.
Ion sieving and desalination: Energy penalty for excess baggage
Devanathan, Ram
2017-04-03
Here, more than a billion people do not have access to clean water globally and millions of people die every year from water borne diseases. Human activity has resulted in depletion of groundwater, seawater intrusion in coastal aquifers, pollution of water resources, ecological damage, and resultant threats to the world’s freshwater, food supply, security, and prosperity. To address this challenge, there is a pressing need to produce clean water from seawater, brackish groundwater, and waste water. Current desalination methods are energy intensive and produce adverse environmental impact. At the same time, energy production consumes large quantities of water and createsmore » waste water that needs to be treated with further energy input. Water treatment with membranes that separate water molecules from ions, pathogens and pollutants has been proposed as an energy-efficient solution to the fresh water crisis. Recently, membranes based on carbon nanotubes, graphene and graphene oxide (GO) have garnered considerable interest for their potential in desalination. Of these, GO membranes hold the promise of inexpensive production on a large scale but swell when immersed in water. The swollen membrane allows not only water molecules but also ions, such as Na + and Mg 2+, to pass through. Abraham and coworkers show that the interlayer spacing in a GO laminar membrane can be tuned to a certain value and then fixed by physically restraining the membrane from swelling. When the authors reduced the spacing systematically in steps from 9.8 Å to 7.4 Å, the ion permeation rate was reduced by two orders of magnitude while the water permeation rate was only halved.« less
Recoil implantation of boron into silicon by high energy silicon ions
NASA Astrophysics Data System (ADS)
Shao, L.; Lu, X. M.; Wang, X. M.; Rusakova, I.; Mount, G.; Zhang, L. H.; Liu, J. R.; Chu, Wei-Kan
2001-07-01
A recoil implantation technique for shallow junction formation was investigated. After e-gun deposition of a B layer onto Si, 10, 50, or 500 keV Si ion beams were used to introduce surface deposited B atoms into Si by knock-on. It has been shown that recoil implantation with high energy incident ions like 500 keV produces a shallower B profile than lower energy implantation such as 10 keV and 50 keV. This is due to the fact that recoil probability at a given angle is a strong function of the energy of the primary projectile. Boron diffusion was showed to be suppressed in high energy recoil implantation and such suppression became more obvious at higher Si doses. It was suggested that vacancy rich region due to defect imbalance plays the role to suppress B diffusion. Sub-100 nm junction can be formed by this technique with the advantage of high throughput of high energy implanters.
Lifetimes of relativistic heavy-ion beams in the High Energy Storage Ring of FAIR
NASA Astrophysics Data System (ADS)
Shevelko, V. P.; Litvinov, Yu. A.; Stöhlker, Th.; Tolstikhina, I. Yu.
2018-04-01
The High Energy Storage Ring, HESR, will be constructed at the Facility for Antiproton and Ion Research, FAIR, Darmstadt. For the first time, it will be possible to perform experiments with cooled high-intensity stable and radioactive heavy ions at highly relativistic energies. To design experiments at the HESR, realistic estimations of beam lifetimes are indispensable. Here we report calculated cross sections and lifetimes for typical U88+ , U90+ , U92+ , Sn49+ and Sn50+ ions in the energy range E = 400 MeV/u-5 GeV/u, relevant for the HESR. Interactions with the residual gas and with internal gas-jet targets are also considered.
Coulomb and nuclear excitations of narrow resonances in 17Ne
Marganiec, J.; Wamers, F.; Aksouh, F.; ...
2016-05-25
New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the 15O+p +p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of datamore » from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. Finally, the resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure.« less
Z-dependence of mean excitation energies for second and third row atoms and their ions
NASA Astrophysics Data System (ADS)
Sauer, Stephan P. A.; Sabin, John R.; Oddershede, Jens
2018-05-01
All mean excitation energies for second and third row atoms and their ions are calculated in the random-phase approximation using large basis sets. To a very good approximation, it turns out that mean excitation energies within an isoelectronic series are a quadratic function of the nuclear charge. It is demonstrated that this behavior is linked to the fact that the contributions from continuum electronic states give the dominate contributions to the mean excitation energies and that these contributions for atomic ions appear hydrogen-like. We argue that this finding may present a method to get a first estimate of mean excitation energies also for other non-relativistic atomic ions.
NASA Astrophysics Data System (ADS)
Runov, A.; Angelopoulos, V.; Artemyev, A.; Lu, S.; Birn, J.; Pritchett, P. L.
2017-12-01
Electron interactions with Electromagnetic Ion Cyclotron (EMIC) amd Magnetosnic (MS) waves are considered as a mechanism of electron acceleration up to relativistic energies in the inner magnetosphere. The free energy for these waves is provided by ion populations with unstable energy distributions. It is established that the perpendicular anisotropy (T_perp > T_par) of energetic ions may provide the free energy for EMIC waves. The ring-type ion distributions are considered as the free energy source for the MS waves. Where and how do these distributions formed? To answer this question, we examined ion distribution functions within earthward-contracting dipolarizing flux bundles (DFBs) observed in the near-Earth plasma sheet at R 10 - 12 RE. It was found that ion distributions are often characterized by the perpendicular anisotropy at supra-thermal energies (at velocities V_thermal ≤ v ≤ 2*V_thermal). The effect was found to be stronger at largerbackground Bz (i.e., closer to the dipole). Similar characteristics wereobserved in particle-in-cell and test-particle simulations. Moreover, the simulations showed the ring-type ion distribution formation. These results suggest that ions, injected towards the inner magnetosphere with DFBs may indeed provide free energy for the EMIC and MS wave excitations.
Kalluri, Sujith; Yoon, Moonsu; Jo, Minki; Liu, Hua Kun; Dou, Shi Xue; Cho, Jaephil; Guo, Zaiping
2017-12-01
Cathode material degradation during cycling is one of the key obstacles to upgrading lithium-ion and beyond-lithium-ion batteries for high-energy and varied-temperature applications. Herein, we highlight recent progress in material surface-coating as the foremost solution to resist the surface phase-transitions and cracking in cathode particles in mono-valent (Li, Na, K) and multi-valent (Mg, Ca, Al) ion batteries under high-voltage and varied-temperature conditions. Importantly, we shed light on the future of materials surface-coating technology with possible research directions. In this regard, we provide our viewpoint on a novel hybrid surface-coating strategy, which has been successfully evaluated in LiCoO 2 -based-Li-ion cells under adverse conditions with industrial specifications for customer-demanding applications. The proposed coating strategy includes a first surface-coating of the as-prepared cathode powders (by sol-gel) and then an ultra-thin ceramic-oxide coating on their electrodes (by atomic-layer deposition). What makes it appealing for industry applications is that such a coating strategy can effectively maintain the integrity of materials under electro-mechanical stress, at the cathode particle and electrode- levels. Furthermore, it leads to improved energy-density and voltage retention at 4.55 V and 45 °C with highly loaded electrodes (≈24 mg.cm -2 ). Finally, the development of this coating technology for beyond-lithium-ion batteries could be a major research challenge, but one that is viable. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
NASA Technical Reports Server (NTRS)
Brinca, A. L.; Tsurutani, B. T.
1987-01-01
The characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies are examined using a model of solar wind permeated by dilute drifting ring distributions of electrons and oxygen ions with finite thermal spreads. The model has parameters compatible with the ICE observations at the Giacobini-Zinner comet. It is shown that cometary newborn ions with large perpendicular energies can excite a wave mode with rest frame frequencies in the order of the heavy ion cyclotron frequency, Omega(i), and unusual propagation characteristics at small obliquity angles. For parallel propagation, the mode is left-hand circularly polarized, might be unstable in a frequency range containing Omega(i), and moves in the direction of the newborn ion drift along the static magnetic field.
Benchmark solutions for the galactic heavy-ion transport equations with energy and spatial coupling
NASA Technical Reports Server (NTRS)
Ganapol, Barry D.; Townsend, Lawrence W.; Lamkin, Stanley L.; Wilson, John W.
1991-01-01
Nontrivial benchmark solutions are developed for the galactic heavy ion transport equations in the straightahead approximation with energy and spatial coupling. Analytical representations of the ion fluxes are obtained for a variety of sources with the assumption that the nuclear interaction parameters are energy independent. The method utilizes an analytical LaPlace transform inversion to yield a closed form representation that is computationally efficient. The flux profiles are then used to predict ion dose profiles, which are important for shield design studies.
Ion energy distributions and densities in the plume of Enceladus
NASA Astrophysics Data System (ADS)
Sakai, Shotaro; Cravens, Thomas E.; Omidi, Nojan; Perry, Mark E.; Waite, J. Hunter
2016-10-01
Enceladus has a dynamic plume that is emitting gas, including water vapor, and dust. The gas is ionized by solar EUV radiation, charge exchange, and electron impact and extends throughout the inner magnetosphere of Saturn. The charge exchange collisions alter the plasma composition. Ice grains (dust) escape from the vicinity of Enceladus and form the E ring, including a portion that is negatively charged by the local plasma. The inner magnetosphere within 10 RS (Saturn radii) contains a complex mixture of plasma, neutral gas, and dust that links back to Enceladus. In this paper we investigate the energy distributions, ion species and densities of water group ions in the plume of Enceladus using test particle and Monte Carlo methods that include collisional processes such as charge exchange and ion-neutral chemical reactions. Ion observations from the Cassini Ion and Neutral Mass Spectrometer (INMS) for E07 are presented for the first time. We use the modeling results to interpret observations made by the Cassini Plasma Spectrometer (CAPS) and the INMS. The low energy ions, as observed by CAPS, appear to be affected by a vertical electric field (EZ=-10 μV/m) in the plume. The EZ field may be associated with the charged dust and/or the pressure gradient of plasma. The model results, along with the results of earlier models, show that H3O+ ions created by chemistry are predominant in the plume, which agrees with INMS and CAPS data, but the INMS count rate in the plume for the model is several times greater than the data, which we do not fully understand. This composition and the total ion count found in the plume agree with INMS and CAPS data. On the other hand, the Cassini Langmuir Probe measured a maximum plume ion density more than 30,000 cm-3, which is far larger than the maximum ion density from our model, 900 cm-3. The model results also demonstrate that most of the ions in the plume are from the external magnetospheric flow and are not generated by local
Conical pitch angle distributions of very low-energy ion fluxes observed by ISEE 1
NASA Technical Reports Server (NTRS)
Horwitz, J. L.; Baugher, C. R.; Chappell, C. R.; Shelley, E. G.; Young, D. T.
1982-01-01
Observations are presented of conical distributions of low-energy ion fluxes from throughout the magnetosphere. The data were provided by the plasma composition experiment (PCE) on ISEE 1. ISEE 1 was launched in October 1977 into a highly elliptical orbit with a 30 deg inclination to the equator and 22.5 earth radii apogee. Particular attention is given to data taken when the instrument was in its thermal plasma mode, sampling ions in the energy per charge range 0-100 eV/e. Attention is given to examples of conical distributions in 0- to 100-eV/e ions, the occurrence of conical distributions of 0- to 100-eV ions in local time-geocentric distance and latitude-geocentric distance coordinates, the cone angles in 0- to 100-eV ion conics, Kp distributions of 0- to 100-eV ion conics, and some compositional aspects of 0- to 100-eV ion conics.
Low-energy ion-backscattering spectroscopies applied to the determination of surface structure
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yarmoff, J.A.
1985-01-01
Low-Energy Ion Scattering (LEIS) was investigated as a means for determining the geometric structure at a single-crystal surface. A three-dimensional Monte-Carlo computer simulation was developed and applied to existing LEIS data. The binary collision approximation was found to yield satisfactory results in simulating Buck's time-of-flight energy spectra for 2.4 keV Ne/sup +/ scattering from Ni(001). A two-atom-layer model was used in calculations of the azimuthal anisotropy of the ion yield measured by Bernheim and Slodzian for 9.5 keV Ne/sup +/ scattering from Cu(001). The calculations were successful in reproducing most of the features that had been observed in the experiments,more » which shows that this model contained most of the physics required to interpret the data. An apparatus for performing LEIS studies was built, and Low-Energy Ion-Backscattering Angular Distributions (LEIBAD) were collected with 3-20 keV /sup 6/Li/sup +/ incident on Cu(001). For incidence along a low-index Miller axis of the crystal, shadowing effects limited the penetration depth of the elastically scattered ions. However, neutralized Li atoms, which were not filtered out of the scattered yield by the high-pass filter, provided a background characteristic of the bulk. A high-resolution electrostatic analyzer was used to collect impact Collision Ion Scattering Spectroscopy (ICISS) data for 5-keV /sup 6/Li/sup +/ ions to study the Cu(110) and Cu(110) (2 x 1)-0 surfaces.« less
Is Perceptual Narrowing Too Narrow?
ERIC Educational Resources Information Center
Cashon, Cara H.; Denicola, Christopher A.
2011-01-01
There is a growing list of examples illustrating that infants are transitioning from having earlier abilities that appear more "universal," "broadly tuned," or "unconstrained" to having later abilities that appear more "specialized," "narrowly tuned," or "constrained." Perceptual narrowing, a well-known phenomenon related to face, speech, and…
NASA Astrophysics Data System (ADS)
Wang, Xiangqin; Yu, Zengliang
2003-08-01
In this paper, samples of solid organic sodium salts (sodium formate, sodium acetate and sodium benzoate) were irradiated by low-energy N+ ions. The induced damage was detected by infrared (FT-IR). It is shown that a new cyano group (-CN) and amino group (-NH2) were formed in the irradiated sodium carbroxylic sample with N+ ion irradiation. The experimental results examined the effect of N+ ion irradiation by reacting with sodium salt molecules, and presented a new way for the synthesis of nitrogenous compound by low-energy ion irradiation.
Feasibility Study on Cardiac Arrhythmia Ablation Using High-Energy Heavy Ion Beams
NASA Astrophysics Data System (ADS)
Lehmann, H. Immo; Graeff, Christian; Simoniello, Palma; Constantinescu, Anna; Takami, Mitsuru; Lugenbiel, Patrick; Richter, Daniel; Eichhorn, Anna; Prall, Matthias; Kaderka, Robert; Fiedler, Fine; Helmbrecht, Stephan; Fournier, Claudia; Erbeldinger, Nadine; Rahm, Ann-Kathrin; Rivinius, Rasmus; Thomas, Dierk; Katus, Hugo A.; Johnson, Susan B.; Parker, Kay D.; Debus, Jürgen; Asirvatham, Samuel J.; Bert, Christoph; Durante, Marco; Packer, Douglas L.
2016-12-01
High-energy ion beams are successfully used in cancer therapy and precisely deliver high doses of ionizing radiation to small deep-seated target volumes. A similar noninvasive treatment modality for cardiac arrhythmias was tested here. This study used high-energy carbon ions for ablation of cardiac tissue in pigs. Doses of 25, 40, and 55 Gy were applied in forced-breath-hold to the atrioventricular junction, left atrial pulmonary vein junction, and freewall left ventricle of intact animals. Procedural success was tracked by (1.) in-beam positron-emission tomography (PET) imaging; (2.) intracardiac voltage mapping with visible lesion on ultrasound; (3.) lesion outcomes in pathohistolgy. High doses (40-55 Gy) caused slowing and interruption of cardiac impulse propagation. Target fibrosis was the main mediator of the ablation effect. In irradiated tissue, apoptosis was present after 3, but not 6 months. Our study shows feasibility to use high-energy ion beams for creation of cardiac lesions that chronically interrupt cardiac conduction.
Performance Characterization of High Energy Commercial Lithium-ion Cells
NASA Technical Reports Server (NTRS)
Schneidegger, Brianne T.
2010-01-01
The NASA Glenn Research Center Electrochemistry Branch performed characterization of commercial lithium-ion cells to determine the cells' performance against Exploration Technology Development Program (ETDP) Key Performance Parameters (KPP). The goals of the ETDP Energy Storage Project require significant improvements in the specific energy of lithium-ion technology over the state-of-the-art. This work supports the high energy cell development for the Constellation customer Lunar Surface Systems (LSS). In support of these goals, testing was initiated in September 2009 with high energy cylindrical cells obtained from Panasonic and E-One Moli. Both manufacturers indicated the capability of their cells to deliver specific energy of at least 180 Wh/kg or higher. Testing is being performed at the NASA Glenn Research Center to evaluate the performance of these cells under temperature, rate, and cycling conditions relevant to the ETDP goals for high energy cells. The cell-level specific energy goal for high energy technology is 180 Wh/kg at a C/10 rate and 0 C. The threshold value is 165 Wh/kg. The goal is to operate for at least 2000 cycles at 100 percent DOD with greater than 80 percent capacity retention. The Panasonic NCR18650 cells were able to deliver nearly 200 Wh/kg at the aforementioned conditions. The E-One Moli ICR18650J cells also met the specific energy goal by delivering 183 Wh/kg. Though both cells met the goal for specific energy, this testing was only one portion of the testing required to determine the suitability of commercial cells for the ETDP. The cells must also meet goals for cycle life and safety. The results of this characterization are summarized in this report.
Investigation of the heavy-ion mode in the FAIR High Energy Storage Ring
NASA Astrophysics Data System (ADS)
Kovalenko, O.; Dolinskii, O.; Litvinov, Yu A.; Maier, R.; Prasuhn, D.; Stöhlker, T.
2015-11-01
High energy storage ring (HESR) as a part of the future accelerator facility FAIR (Facility for Antiproton and Ion Research) will serve for a variety of internal target experiments with high-energy stored heavy ions (SPARC collaboration). Bare uranium is planned to be used as a primary beam. Since a storage time in some cases may be significant—up to half an hour—it is important to examine the high-order effects in the long-term beam dynamics. A new ion optics specifically for the heavy ion mode of the HESR is developed and is discussed in this paper. The subjects of an optics design, tune working point and a dynamic aperture are addressed. For that purpose nonlinear beam dynamics simulations are carried out. Also a flexibility of the HESR ion optical lattice is verified with regard to various experimental setups. Specifically, due to charge exchange reactions in the internal target, secondary beams, such as hydrogen-like and helium-like uranium ions, will be produced. Thus the possibility of separation of these secondary ions and the primary {{{U}}}92+ beam is presented with different internal target locations.
Diagnosing the Fine Structure of Electron Energy Within the ECRIT Ion Source
NASA Astrophysics Data System (ADS)
Jin, Yizhou; Yang, Juan; Tang, Mingjie; Luo, Litao; Feng, Bingbing
2016-07-01
The ion source of the electron cyclotron resonance ion thruster (ECRIT) extracts ions from its ECR plasma to generate thrust, and has the property of low gas consumption (2 sccm, standard-state cubic centimeter per minute) and high durability. Due to the indispensable effects of the primary electron in gas discharge, it is important to experimentally clarify the electron energy structure within the ion source of the ECRIT through analyzing the electron energy distribution function (EEDF) of the plasma inside the thruster. In this article the Langmuir probe diagnosing method was used to diagnose the EEDF, from which the effective electron temperature, plasma density and the electron energy probability function (EEPF) were deduced. The experimental results show that the magnetic field influences the curves of EEDF and EEPF and make the effective plasma parameter nonuniform. The diagnosed electron temperature and density from sample points increased from 4 eV/2×1016 m-3 to 10 eV/4×1016 m-3 with increasing distances from both the axis and the screen grid of the ion source. Electron temperature and density peaking near the wall coincided with the discharge process. However, a double Maxwellian electron distribution was unexpectedly observed at the position near the axis of the ion source and about 30 mm from the screen grid. Besides, the double Maxwellian electron distribution was more likely to emerge at high power and a low gas flow rate. These phenomena were believed to relate to the arrangements of the gas inlets and the magnetic field where the double Maxwellian electron distribution exits. The results of this research may enhance the understanding of the plasma generation process in the ion source of this type and help to improve its performance. supported by National Natural Science Foundation of China (No. 11475137)
Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.
2013-01-01
Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions. PMID:23983449
NASA Astrophysics Data System (ADS)
Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.
2013-07-01
Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.
Rieker, G B; Poehlmann, F R; Cappelli, M A
2013-07-01
Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.
NASA Astrophysics Data System (ADS)
Hasan, M.-A.; Knall, J.; Barnett, S. A.; Rockett, A.; Sundgren, J.-E.
1987-10-01
A single-grid electron-impact ultrahigh vacuum (UHV) compatible low-energy ion gun capable of operating with a low vapor pressure solid source material such as In is presented. The gun consists of a single chamber which integrates the functions of an effusion cell, a vapor transport tube, and a glow discharge ionizer. The initial results of experiments designed to study the role of ion/surface interactions during nucleation and the early stages of crystal growth in UHV revealed that, for deposition on amorphous substrates, the use of a partially ionized In(+) beam resulted in a progressive shift towards larger island sizes, a decreased rate of secondary nucleation, and a more uniform island size distribution.
Synthesis Of Noble Metal Nanoparticle Composite Glasses Using Low Energy Ion Beam Mixing
NASA Astrophysics Data System (ADS)
Varma, Ranjana S.; Kothari, D. C.; Mahadkar, A. G.; Kulkarni, N. A.; Kanjilal, D.; Kumar, P.
2010-12-01
Carbon coated thin films of Cu or Au on fused silica glasses have been irradiated using 100 keV Ar+ ions at different fluences ranging from 1×1013 to 1×1016 ion/cm2. In this article, we explore a route to form noble metal nanoparticles in amorphous glass matrices without post irradiation annealing using low energy ion beam mixing where nuclear energy loss process is dominant. Optical and structural properties were studied using UV-Vis-NIR absorbance spectroscopy and Glancing angle X-ray Diffraction (GXRD). Results showed that Cu and Au nanoparticles are formed at higher fluence of 1×1016 ion/cm2 used in this work without annealing. The diameters of metal nanoparticles obtained from UV-Vis NIR and GXRD are in agreement.
High Interfacial Barriers at Narrow Carbon Nanotube-Water Interfaces.
Varanasi, Srinivasa Rao; Subramanian, Yashonath; Bhatia, Suresh K
2018-06-26
Water displays anomalous fast diffusion in narrow carbon nanotubes (CNTs), a behavior that has been reproduced in both experimental and simulation studies. However, little is reported on the effect of bulk water-CNT interfaces, which is critical to exploiting the fast transport of water across narrow carbon nanotubes in actual applications. Using molecular dynamics simulations, we investigate here the effect of such interfaces on the transport of water across arm-chair CNTs of different diameters. Our results demonstrate that diffusion of water is significantly retarded in narrow CNTs due to bulk regions near the pore entrance. The slowdown of dynamics can be attributed to the presence of large energy barriers at bulk water-CNT interfaces. The presence of such intense barriers at the bulk-CNT interface arises due to the entropy contrast between the bulk and confined regions, with water molecules undergoing high translational and rotational entropy gain on entering from the bulk to the CNT interior. The intensity of such energy barriers decreases with increase in CNT diameter. These results are very important for emerging technological applications of CNTs and other nanoscale materials, such as in nanofluidics, water purification, nanofiltration, and desalination, as well as for biological transport processes.
Zheng, Jun-Sheng; Zhang, Lei; Shellikeri, Annadanesh; Cao, Wanjun; Wu, Qiang; Zheng, Jim P
2017-02-07
Li ion battery (LIB) and electrochemical capacitor (EC) are considered as the most widely used energy storage systems (ESSs) because they can produce a high energy density or a high power density, but it is a huge challenge to achieve both the demands of a high energy density as well as a high power density on their own. A new hybrid Li ion capacitor (HyLIC), which combines the advantages of LIB and Li ion capacitor (LIC), is proposed. This device can successfully realize a potential match between LIB and LIC and can avoid the excessive depletion of electrolyte during the charge process. The galvanostatic charge-discharge cycling tests reveal that at low current, the HyLIC exhibits a high energy density, while at high current, it demonstrates a high power density. Ragone plot confirms that this device can make a synergetic balance between energy and power and achieve a highest energy density in the power density range of 80 to 300 W kg -1 . The cycle life test proves that HyLIC exhibits a good cycle life and an excellent coulombic efficiency. The present study shows that HyLIC, which is capable of achieving a high energy density, a long cycle life and an excellent power density, has the potential to achieve the winning combination of a high energy and power density.
Zheng, Jun-Sheng; Zhang, Lei; Shellikeri, Annadanesh; Cao, Wanjun; Wu, Qiang; Zheng, Jim P.
2017-01-01
Li ion battery (LIB) and electrochemical capacitor (EC) are considered as the most widely used energy storage systems (ESSs) because they can produce a high energy density or a high power density, but it is a huge challenge to achieve both the demands of a high energy density as well as a high power density on their own. A new hybrid Li ion capacitor (HyLIC), which combines the advantages of LIB and Li ion capacitor (LIC), is proposed. This device can successfully realize a potential match between LIB and LIC and can avoid the excessive depletion of electrolyte during the charge process. The galvanostatic charge-discharge cycling tests reveal that at low current, the HyLIC exhibits a high energy density, while at high current, it demonstrates a high power density. Ragone plot confirms that this device can make a synergetic balance between energy and power and achieve a highest energy density in the power density range of 80 to 300 W kg−1. The cycle life test proves that HyLIC exhibits a good cycle life and an excellent coulombic efficiency. The present study shows that HyLIC, which is capable of achieving a high energy density, a long cycle life and an excellent power density, has the potential to achieve the winning combination of a high energy and power density. PMID:28169329
Nanopatterning of optical surfaces during low-energy ion beam sputtering
NASA Astrophysics Data System (ADS)
Liao, Wenlin; Dai, Yifan; Xie, Xuhui
2014-06-01
Ion beam figuring (IBF) provides a highly deterministic method for high-precision optical surface fabrication, whereas ion-induced microscopic morphology evolution would occur on surfaces. Consequently, the fabrication specification for surface smoothness must be seriously considered during the IBF process. In this work, low-energy ion nanopatterning of our frequently used optical material surfaces is investigated to discuss the manufacturability of an ultrasmooth surface. The research results indicate that ion beam sputtering (IBS) can directly smooth some amorphous or amorphizable material surfaces, such as fused silica, Si, and ULE under appropriate processing conditions. However, for IBS of a Zerodur surface, preferential sputtering together with curvature-dependent sputtering overcome ion-induced smoothing mechanisms, leading to the granular nanopatterns' formation and the coarsening of the surface. Furthermore, the material property difference at microscopic scales and the continuous impurity incorporation would affect the ion beam smoothing of optical surfaces. Overall, IBS can be used as a promising technique for ultrasmooth surface fabrication, which strongly depends on processing conditions and material characters.
Physics perspectives of heavy-ion collisions at very high energy
Chang, Ning-bo; Cao, ShanShan; Chen, Bao-yi; ...
2016-01-15
We expect heavy-ion collisions at very high colliding energies to produce a quark-gluon plasma (QGP) at the highest temperature obtainable in a laboratory setting. Experimental studies of these reactions can provide an unprecedented range of information on properties of the QGP at high temperatures. We also report theoretical investigations of the physics perspectives of heavy-ion collisions at a future high-energy collider. These include initial parton production, collective expansion of the dense medium, jet quenching, heavy-quark transport, dissociation and regeneration of quarkonia, photon and dilepton production. Here, we illustrate the potential of future experimental studies of the initial particle production andmore » formation of QGP at the highest temperature to provide constraints on properties of strongly interaction matter.« less
Low energy ion distribution measurements in Madison Symmetric Torus plasmas
DOE Office of Scientific and Technical Information (OSTI.GOV)
Titus, J. B., E-mail: jtitus@cepast.famu.edu; Mezonlin, E. D.; Johnson, J. A.
2014-06-15
Charge-exchange neutrals contain information about the contents of a plasma and can be detected as they escape confinement. The Florida A and M University compact neutral particle analyzer (CNPA), used to measure the contents of neutral particle flux, has been reconfigured, calibrated, and installed on the Madison Symmetric Torus (MST) for high temperature deuterium plasmas. The energy range of the CNPA has been extended to cover 0.34–5.2 keV through an upgrade of the 25 detection channels. The CNPA has been used on all types of MST plasmas at a rate of 20 kHz throughout the entire discharge (∼70 ms). Plasma parameter scans showmore » that the ion distribution is most dependent on the plasma current. Magnetic reconnection events throughout these scans produce stronger poloidal electric fields, stronger global magnetic modes, and larger changes in magnetic energy all of which heavily influence the non-Maxwellian part of the ion distribution (the fast ion tail)« less
Statistical Characterization of 18650-Format Lithium-Ion Cell Thermal Runaway Energy Distributions
NASA Technical Reports Server (NTRS)
Walker, William Q.; Rickman, Steven; Darst, John; Finegan, Donal; Bayles, Gary; Darcy, Eric
2017-01-01
Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh/kg) and moderate energy (200 Wh/kg) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 1/4m). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature.
Investigation of high-energy ion-irradiated MA957 using synchrotron radiation under in-situ tension
Mo, Kun; Yun, Di; Miao, Yinbin; ...
2016-01-02
In this paper, an MA957 oxide dispersion-strengthened (ODS) alloy was irradiated with high-energy ions in the Argonne Tandem Linac Accelerator System. Fe ions at an energy of 84 MeV bombarded MA957 tensile specimens, creating a damage region similar to 7.5 μm in depth; the peak damage (similar to 40 dpa) was estimated to be at similar to 7 μm from the surface. Following the irradiation, in-situ high-energy X-ray diffraction measurements were performed at the Advanced Photon Source in order to study the dynamic deformation behavior of the specimens after ion irradiation damage. In-situ X-ray measurements taken during tensile testing ofmore » the ion-irradiated MA957 revealed a difference in loading behavior between the irradiated and un-irradiated regions of the specimen. At equivalent applied stresses, lower lattice strains were found in the radiation-damaged region than those in the un-irradiated region. This might be associated with a higher level of Type II stresses as a result of radiation hardening. The study has demonstrated the feasibility of combining high-energy ion radiation and high-energy synchrotron X-ray diffraction to study materials' radiation damage in a dynamic manner.« less
Li, Yan; Wang, Dengchao; Kvetny, Maksim M; Brown, Warren; Liu, Juan; Wang, Gangli
2015-01-01
The dynamics of ion transport at nanostructured substrate-solution interfaces play vital roles in high-density energy conversion, stochastic chemical sensing and biosensing, membrane separation, nanofluidics and fundamental nanoelectrochemistry. Further advancements in these applications require a fundamental understanding of ion transport at nanoscale interfaces. The understanding of the dynamic or transient transport, and the key physical process involved, is limited, which contrasts sharply with widely studied steady-state ion transport features at atomic and nanometer scale interfaces. Here we report striking time-dependent ion transport characteristics at nanoscale interfaces in current-potential ( I - V ) measurements and theoretical analyses. First, a unique non-zero I - V cross-point and pinched I - V curves are established as signatures to characterize the dynamics of ion transport through individual conical nanopipettes. Second, ion transport against a concentration gradient is regulated by applied and surface electrical fields. The concept of ion pumping or separation is demonstrated via the selective ion transport against concentration gradients through individual nanopipettes. Third, this dynamic ion transport process under a predefined salinity gradient is discussed in the context of nanoscale energy conversion in supercapacitor type charging-discharging, as well as chemical and electrical energy conversion. The analysis of the emerging current-potential features establishes the urgently needed physical foundation for energy conversion employing ordered nanostructures. The elucidated mechanism and established methodology can be generalized into broadly-defined nanoporous materials and devices for improved energy, separation and sensing applications.
Li, Yan; Wang, Dengchao; Kvetny, Maksim M.; ...
2014-08-20
The dynamics of ion transport at nanostructured substrate–solution interfaces play vital roles in high-density energy conversion, stochastic chemical sensing and biosensing, membrane separation, nanofluidics and fundamental nanoelectrochemistry. Advancements in these applications require a fundamental understanding of ion transport at nanoscale interfaces. The understanding of the dynamic or transient transport, and the key physical process involved, is limited, which contrasts sharply with widely studied steady-state ion transport features at atomic and nanometer scale interfaces. Here we report striking time-dependent ion transport characteristics at nanoscale interfaces in current–potential (I–V) measurements and theoretical analyses. First, a unique non-zero I–V cross-point and pinched I–Vmore » curves are established as signatures to characterize the dynamics of ion transport through individual conical nanopipettes. Moreoever, ion transport against a concentration gradient is regulated by applied and surface electrical fields. The concept of ion pumping or separation is demonstrated via the selective ion transport against concentration gradients through individual nanopipettes. Third, this dynamic ion transport process under a predefined salinity gradient is discussed in the context of nanoscale energy conversion in supercapacitor type charging–discharging, as well as chemical and electrical energy conversion. Our analysis of the emerging current–potential features establishes the urgently needed physical foundation for energy conversion employing ordered nanostructures. The elucidated mechanism and established methodology can be generalized into broadly-defined nanoporous materials and devices for improved energy, separation and sensing applications.« less
Harvey, Z; Thakur, S Chakraborty; Hansen, A; Hardin, R; Przybysz, W S; Scime, E E
2008-10-01
We present ion velocity distribution function (IVDF) measurements obtained with a five grid retarding field energy analyzer (RFEA) and IVDF measurements obtained with laser induced fluorescence (LIF) for an expanding helicon plasma. The ion population consists of a background population and an energetic ion beam. When the RFEA measurements are corrected for acceleration due to the electric potential difference across the plasma sheath, we find that the RFEA measurements indicate a smaller background to beam density ratio and a much larger parallel ion temperature than the LIF. The energy of the ion beam is the same in both measurements. These results suggest that ion heating occurs during the transit of the background ions through the sheath and that LIF cannot detect the fraction of the ion beam whose metastable population has been eliminated by collisions.
Effects of a chirped bias voltage on ion energy distributions in inductively coupled plasma reactors
NASA Astrophysics Data System (ADS)
Lanham, Steven J.; Kushner, Mark J.
2017-08-01
The metrics for controlling reactive fluxes to wafers for microelectronics processing are becoming more stringent as feature sizes continue to shrink. Recent strategies for controlling ion energy distributions to the wafer involve using several different frequencies and/or pulsed powers. Although effective, these strategies are often costly or present challenges in impedance matching. With the advent of matching schemes for wide band amplifiers, other strategies to customize ion energy distributions become available. In this paper, we discuss results from a computational investigation of biasing substrates using chirped frequencies in high density, electronegative inductively coupled plasmas. Depending on the frequency range and chirp duration, the resulting ion energy distributions exhibit components sampled from the entire frequency range. However, the chirping process also produces transient shifts in the self-generated dc bias due to the reapportionment of displacement and conduction with frequency to balance the current in the system. The dynamics of the dc bias can also be leveraged towards customizing ion energy distributions.
NASA Technical Reports Server (NTRS)
Barbosa, D. D.
1986-01-01
A theory of medium-energy (about keV) electrons and heavy ions in Jupiter's magnetosphere is presented. Lower hybrid waves are generated by the combined effects of a ring instability of neutral wind pickup ions and the modified two-stream instability associated with transport of cool Iogenic plasma. The quasi-linear energy diffusion coefficient for lower hybrid wave-particle interactions is evaluated, and several solutions to the diffusion equation are given. Calculations based on measured wave properties show that the noise substantially modifies the particle distribution functions. The effects are to accelerate superthermal ions and electrons to keV energies and to thermalize the pickup ions on time scales comparable to the particle residence time. The S(2+)/S(+) ratio at medium energies is a measure of the relative contribution from Iogenic thermal plasma and neutral wind ions, and this important quantity should be determined from future measurements. The theory also predicts a preferential acceleration of heavy ions with an accleration time that scales inversely with the root of the ion mass. Electrons accelerated by the process contribute to further reionization of the neutral wind by electron impact, thus providing a possible confirmation of Alfven's critical velocity effect in the Jovian magnetosphere.
Leung, Ka-Ngo; Ehlers, Kenneth W.
1984-01-01
A magnetic filter for an ion source reduces the production of undesired ion species and improves the ion beam quality. High-energy ionizing electrons are confined by the magnetic filter to an ion source region, where the high-energy electrons ionize gas molecules. One embodiment of the magnetic filter uses permanent magnets oriented to establish a magnetic field transverse to the direction of travel of ions from the ion source region to the ion extraction region. In another embodiment, low energy 16 eV electrons are injected into the ion source to dissociate gas molecules and undesired ion species into desired ion species.
Local time variations of high-energy plasmaspheric ion pitch angle distributions
Sarno-Smith, Lois K.; Liemohn, Michael W.; Skoug, Ruth M.; ...
2016-07-01
Recent observations from the Van Allen Probes Helium Oxygen Proton Electron (HOPE) instrument revealed a persistent depletion in the 1–10 eV ion population in the postmidnight sector during quiet times in the 2 < L < 3 region. This study explores the source of this ion depletion by developing an algorithm to classify 26 months of pitch angle distributions measured by the HOPE instrument. We correct the HOPE low energy fluxes for spacecraft potential using measurements from the Electric Field and Waves (EFW) instrument. A high percentage of low count pitch angle distributions is found in the postmidnight sector coupledmore » with a low percentage of ion distributions peaked perpendicular to the field line. A peak in loss cone distributions in the dusk sector is also observed. Here, these results characterize the nature of the dearth of the near 90° pitch angle 1–10 eV ion population in the near-Earth postmidnight sector. This study also shows, for the first time, low-energy HOPE differential number fluxes corrected for spacecraft potential and 1–10 eV H + fluxes at different levels of geomagnetic activity.« less
Formation of donors in germanium–silicon alloys implanted with hydrogen ions with different energies
DOE Office of Scientific and Technical Information (OSTI.GOV)
Pokotilo, Yu. M., E-mail: Pokotilo@bsu.by; Petukh, A. N.; Litvinov, V. V.
2016-08-15
The distributions of hydrogen-containing donors in Ge{sub 1–x}Si{sub x} (0 ≤ x ≤ 0.06) alloys implanted with hydrogen ions with an energy of 200 and 300 keV and a dose of 1 × 10{sup 15} cm{sup –2} are studied. It is established that, at the higher ion energy, the limiting donor concentration after postimplantation heat treatment (275°C) is attained within ~30 min and, at the lower energy, within ~320 min. In contrast to donors formed near the surface, a portion of hydrogen-containing donors formed upon the implantation of ions with the higher energy possess the property of bistability. The limitingmore » donor concentration is independent of the ion energy, but decreases from 1.3 × 10{sup 16} to 1.5 × 10{sup 15} cm{sup –3}, as the Si impurity content in the alloy is increased from x = 0.008 to x = 0.062. It is inferred that the observed differences arise from the participation of the surface in the donor formation process, since the surface significantly influences defect-formation processes involving radiation-induced defects, whose generation accompanies implantation.« less
NASA Technical Reports Server (NTRS)
Vestrand, W. Thomas
1990-01-01
This paper presents a new radiation diagnostic for assaying the energy spectrum and the angular distribution of energetic ions incident on thick hydrogen-rich thermal targets. This diagnostic compares the number of emergent photons in the narrow neutron capture line at 2.223 MeV to the number of Compton scattered photons that form a low-energy tail on the line. It is shown that the relative strength of the tail can be used as a measure of the hardness of the incident ion-energy spectrum. Application of this diagnostic to solar flare conditions is the main thrust of the work presented here. It is examined how the strength of the Compton tail varies with flare viewing angle and the angular distribution of the flare-accelerated particles. Application to compact X-ray binary systems is also briefly discussed.
A silicon strip detector array for energy verification and quality assurance in heavy ion therapy.
Debrot, Emily; Newall, Matthew; Guatelli, Susanna; Petasecca, Marco; Matsufuji, Naruhiro; Rosenfeld, Anatoly B
2018-02-01
The measurement of depth dose profiles for range and energy verification of heavy ion beams is an important aspect of quality assurance procedures for heavy ion therapy facilities. The steep dose gradients in the Bragg peak region of these profiles require the use of detectors with high spatial resolution. The aim of this work is to characterize a one dimensional monolithic silicon detector array called the "serial Dose Magnifying Glass" (sDMG) as an independent ion beam energy and range verification system used for quality assurance conducted for ion beams used in heavy ion therapy. The sDMG detector consists of two linear arrays of 128 silicon sensitive volumes each with an effective size of 2mm × 50μm × 100μm fabricated on a p-type substrate at a pitch of 200 μm along a single axis of detection. The detector was characterized for beam energy and range verification by measuring the response of the detector when irradiated with a 290 MeV/u 12 C ion broad beam incident along the single axis of the detector embedded in a PMMA phantom. The energy of the 12 C ion beam incident on the detector and the residual energy of an ion beam incident on the phantom was determined from the measured Bragg peak position in the sDMG. Ad hoc Monte Carlo simulations of the experimental setup were also performed to give further insight into the detector response. The relative response profiles along the single axis measured with the sDMG detector were found to have good agreement between experiment and simulation with the position of the Bragg peak determined to fall within 0.2 mm or 1.1% of the range in the detector for the two cases. The energy of the beam incident on the detector was found to vary less than 1% between experiment and simulation. The beam energy incident on the phantom was determined to be (280.9 ± 0.8) MeV/u from the experimental and (280.9 ± 0.2) MeV/u from the simulated profiles. These values coincide with the expected energy of 281 MeV/u. The sDMG detector
Investigation of charge stripping scheme for uranium ions at 1-20 MeV/nucleon
NASA Astrophysics Data System (ADS)
Kuboki, Hironori; Harada, Hiroyuki; Saha, Pranab K.
2018-05-01
We investigated a possibility to obtain charge distributions of uranium ions under the conditions to meet the requirements of the booster synchrotron proposed for heavy ion acceleration at J-PARC. The charge distribution is expected to have a width as narrow as possible to realize multi-charge acceleration. The main candidate of stripping material is a carbon foil because we can obtain narrower distributions than gas stripper and a lot of data is available. Besides that, the thickness of the stripping material should be less than 142 μg cm-2 because the energy loss in the stripping material would be compensated by an auxiliary accelerating cavity in the synchrotron ring. We studied the impact energy with which the charge distribution attains equilibrium within this thickness and has the narrowest width. The width is estimated over 1-20 MeV/nucleon by the calculation using the ionization and electron capture cross sections. Scaling factors are introduced to reproduce the experimental data and are determined to be 2.0 and 0.08 for the cross sections of ionization and electron capture, respectively. We concluded that the narrowest width can be obtained at 5.5 MeV/nucleon with a 109-μg cm-2-thick carbon foil.
Influence of several metal ions on the gelation activation energy of silicon tetraethoxide
NASA Technical Reports Server (NTRS)
Bansal, Narottam P.
1988-01-01
The effects of nine metal cations (Li(+), Na(+), Mg(2+), Ca(2+), Sr(2+), Cu(2+), Al(3+), La(3+), and Y(3+) on silica gel formation has been investigated by studying the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) in the presence of metal nitrates. The influence of water: TEOS mole ratio, metal ion concentration, and the reaction temperature has been investigated. The overall activation energy for gel formation has been determined from the temperature dependence of the time of gelation for each system. The activation energy for -Si-O-Si- network formation is found to be 54.5 kJ/mol. The gel formation time as well as the activation energy sharply increase in the presence of Cu(2+), Al(3+), La(3+) and Y(3+). In contrast, the presence of Li(+), Na(+), Mg(2+), Ca(2+), or, Sr(2+) lowers the gelation time, but has no appreciable effect on the activation energy. This difference may be attributed to the participation or nonparticipation of the metal ions in the formation of the three-dimensional polymeric network during the polycondensation step. The concentration of metal ion (Mg(2+), Ca(2+), Y(3+) or the water: TEOS mole ratio had no appreciable effect on the gelation activation energy. A simple test has been proposed to determine whether a metal ion would act as a network intermediate or modifier in silica and other glassy networks.
Ion distributions in RC at different energy levels retrieved from TWINS ENA images by voxel CT tech
NASA Astrophysics Data System (ADS)
Ma, S. Y.; McComas, David; Xu, Liang; Goldstein, Jerry; Yan, Wei-Nan
2012-07-01
Distributions of energetic ions in the RC regions in different energy levels are retrieved by using 3-D voxel CT inversion method from ENA measurements onboard TWINS constellation during the main phase of a moderate geomagnetic storm. It is assumed that the ion flux distribution in the RC is anisotropic in regard to pitch angle which complies with the adiabatic invariance of the magnetic moment as ion moving in the dipole magnetic mirror field. A semi-empirical model of the RC ion distribution in the magnetic equator is quoted to form the ion flux distribution shape at off-equatorial latitudes by mapping. For the concerned time interval, the two satellites of the TWINS flying in double Molnia orbits were located in nearly the same meridian plane at vantage points widely separated in magnetic local time, and both more than 5 RE geocentric distance from the Earth. The ENA data used in this study are differential fluxes averaged over 12 sweeps (corresponding to an interval of 16 min.) at different energy levels ranging from about 1 to 100 keV. The retrieved ion distributions show that in total the main part of the RC is located in the region with L value larger than 4, tending to increase at larger L. It reveals that there are two distinct dominant energy bands at which the ion fluxes are significantly larger magnitude than at other energy levels, one is at lower level around 2 keV and the other at higher level of 30-100 keV. Furthermore, it is very interesting that the peak fluxes of the RC ions at the two energy bands occurred in different magnetic local time, low energy ions appear preferentially in after midnight, while the higher energy ions mainly distributed around midnight and pre-midnight. This new profile is worthy of further study and needs to be demonstrated by more cases.
NASA Technical Reports Server (NTRS)
Fossum, J. G.; Lindholm, F. A.; Shibib, M. A.
1979-01-01
Experimental data demonstrating the sensitivity of open-circuit voltage to front-surface conditions are presented for a variety of p-n-junction silicon solar cells. Analytical models accounting for the data are defined and supported by additional experiments. The models and the data imply that a) surface recombination significantly limits the open-circuit voltage (and the short-circuit current) of typical silicon cells, and b) energy-bandgap narrowing is important in the manifestation of these limitations. The models suggest modifications in both the structural design and the fabrication processing of the cells that would result in substantial improvements in cell performance. The benefits of one such modification - the addition of a thin thermal silicon-dioxide layer on the front surface - are indicated experimentally.
A Quasi-Solid-State Sodium-Ion Capacitor with High Energy Density.
Wang, Faxing; Wang, Xiaowei; Chang, Zheng; Wu, Xiongwei; Liu, Xiang; Fu, Lijun; Zhu, Yusong; Wu, Yuping; Huang, Wei
2015-11-18
A quasi-solid-state sodium-ion capacitor is demonstrated with nanoporous disordered carbon and macroporous graphene as the negative and positive electrodes, respectively, using a sodium-ion-conducting gel polymer electrolyte. It can operate at a cell voltage as high as 4.2 V with an energy density of record high 168 W h kg(-1). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Melhem, N; El Balaa, H; Younes, G; Al Kattar, Z
2017-06-15
The Secondary Standard Dosimetry Laboratory at the Lebanese Atomic Energy Commission has different calibration methods for various types of dosimeters used in industrial, military and medical fields. The calibration is performed using different beams of X-rays (low and medium energy) and Gamma radiation delivered by a Cesium 137 source. The Secondary Standard Dosimetry laboratory in charge of calibration services uses different protocols for the determination of high and low air kerma rate and for narrow and wide series. In order to perform this calibration work, it is very important to identify all the beam characteristics for the different types of sources and qualities of radiation. The following work describes the methods used for the determination of different beam characteristics and calibration coefficients with their uncertainties in order to enhance the radiation protection of workers and patient applications in the fields of medical diagnosis and industrial X-ray. All the characteristics of the X-ray beams are determined for the narrow spectrum series in the 40 and 200 keV range where the inherent filtration, the current intensity, the high voltage, the beam profile and the total uncertainty are the specific characteristics of these X-ray beams. An X-ray software was developed in order to visualize the reference values according to the characteristics of each beam. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Parfanovich, D.M.; Semchinova, A.M.; Flerov, G.N.
1957-08-01
The dependence of ramge on energy has been measured for N and O ions in E-1 Ilford emulsions for energies between 3 to 120 Mev. The results are compared with theoretical predictions. It is also estimated at what energy the N and O ions lose all their electrons on tranversal of matter. (tr-auth)
NASA Astrophysics Data System (ADS)
Braenzel, J.; Barriga-Carrasco, M. D.; Morales, R.; Schnürer, M.
2018-05-01
We investigate, both experimentally and theoretically, how the spectral distribution of laser accelerated carbon ions can be filtered by charge exchange processes in a double foil target setup. Carbon ions at multiple charge states with an initially wide kinetic energy spectrum, from 0.1 to 18 MeV, were detected with a remarkably narrow spectral bandwidth after they had passed through an ultrathin and partially ionized foil. With our theoretical calculations, we demonstrate that this process is a consequence of the evolution of the carbon ion charge states in the second foil. We calculated the resulting spectral distribution separately for each ion species by solving the rate equations for electron loss and capture processes within a collisional radiative model. We determine how the efficiency of charge transfer processes can be manipulated by controlling the ionization degree of the transfer matter.
NASA Technical Reports Server (NTRS)
Cucinotta, F. A.; Katz, R.; Wilson, J. W.
1998-01-01
An analytic method is described for evaluating the average radial electron spectrum and the radial and total frequency-event spectrum for high-energy ions. For high-energy ions, indirect events make important contributions to frequency-event spectra. The method used for evaluating indirect events is to fold the radial electron spectrum with measured frequency-event spectrum for photons or electrons. The contribution from direct events is treated using a spatially restricted linear energy transfer (LET). We find that high-energy heavy ions have a significantly reduced frequency-averaged final energy (yF) compared to LET, while relativistic protons have a significantly increased yF and dose-averaged lineal energy (yD) for typical site sizes used in tissue equivalent proportional counters. Such differences represent important factors in evaluating event spectra with laboratory beams, in space- flight, or in atmospheric radiation studies and in validation of radiation transport codes. The inadequacy of LET as descriptor because of deviations in values of physical quantities, such as track width, secondary electron spectrum, and yD for ions of identical LET is also discussed.
Ion Move Brownian Dynamics (IMBD)--simulations of ion transport.
Kurczynska, Monika; Kotulska, Malgorzata
2014-01-01
Comparison of the computed characteristics and physiological measurement of ion transport through transmembrane proteins could be a useful method to assess the quality of protein structures. Simulations of ion transport should be detailed but also timeefficient. The most accurate method could be Molecular Dynamics (MD), which is very time-consuming, hence is not used for this purpose. The model which includes ion-ion interactions and reduces the simulation time by excluding water, protein and lipid molecules is Brownian Dynamics (BD). In this paper a new computer program for BD simulation of the ion transport is presented. We evaluate two methods for calculating the pore accessibility (round and irregular shape) and two representations of ion sizes (van der Waals diameter and one voxel). Ion Move Brownian Dynamics (IMBD) was tested with two nanopores: alpha-hemolysin and potassium channel KcsA. In both cases during the simulation an ion passed through the pore in less than 32 ns. Although two types of ions were in solution (potassium and chloride), only ions which agreed with the selectivity properties of the channels passed through the pores. IMBD is a new tool for the ion transport modelling, which can be used in the simulations of wide and narrow pores.
DYNAMICS OF HIGH ENERGY IONS AT A STRUCTURED COLLISIONLESS SHOCK FRONT
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gedalin, M.; Dröge, W.; Kartavykh, Y. Y., E-mail: gedalin@bgu.ac.il
2016-07-10
Ions undergoing first-order Fermi acceleration at a shock are scattered in the upstream and downstream regions by magnetic inhomogeneities. For high energy ions this scattering is efficient at spatial scales substantially larger than the gyroradius of the ions. The transition from one diffusive region to the other occurs via crossing the shock, and the ion dynamics during this crossing is mainly affected by the global magnetic field change between the upstream and downstream region. We study the effects of the fine structure of the shock front, such as the foot-ramp-overshoot profile and the phase-standing upstream and downstream magnetic oscillations. Wemore » also consider time dependent features, including reformation and large amplitude coherent waves. We show that the influence of the spatial and temporal structure of the shock front on the dependence of the transition and reflection on the pitch angle of the ions is already weak at ion speeds five times the speed of the upstream flow.« less
Enhancement of optical absorption of Si (100) surfaces by low energy N+ ion beam irradiation
NASA Astrophysics Data System (ADS)
Bhowmik, Dipak; Karmakar, Prasanta
2018-05-01
The increase of optical absorption efficiency of Si (100) surface by 7 keV and 8 keV N+ ions bombardment has been reported here. A periodic ripple pattern on surface has been observed as well as silicon nitride is formed at the ion impact zones by these low energy N+ ion bombardment [P. Karmakar et al., J. Appl. Phys. 120, 025301 (2016)]. The light absorption efficiency increases due to the presence of silicon nitride compound as well as surface nanopatterns. The Atomic Force Microscopy (AFM) study shows the formation of periodic ripple pattern and increase of surface roughness with N+ ion energy. The enhancement of optical absorption by the ion bombarded Si, compared to the bare Si have been measured by UV - visible spectrophotometer.
Rocking-Chair Ammonium-Ion Battery: A Highly Reversible Aqueous Energy Storage System.
Wu, Xianyong; Qi, Yitong; Hong, Jessica J; Li, Zhifei; Hernandez, Alexandre S; Ji, Xiulei
2017-10-09
Aqueous rechargeable batteries are promising solutions for large-scale energy storage. Such batteries have the merit of low cost, innate safety, and environmental friendliness. To date, most known aqueous ion batteries employ metal cation charge carriers. Here, we report the first "rocking-chair" NH 4 -ion battery of the full-cell configuration by employing an ammonium Prussian white analogue, (NH 4 ) 1.47 Ni[Fe(CN) 6 ] 0.88 , as the cathode, an organic solid, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), as the anode, and 1.0 m aqueous (NH 4 ) 2 SO 4 as the electrolyte. This novel aqueous ammonium-ion battery demonstrates encouraging electrochemical performance: an average operation voltage of ca. 1.0 V, an attractive energy density of ca. 43 Wh kg -1 based on both electrodes' active mass, and excellent cycle life over 1000 cycles with 67 % capacity retention. Importantly, the topochemistry results of NH 4 + in these electrodes point to a new paradigm of NH 4 + -based energy storage. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
NASA Astrophysics Data System (ADS)
Mikšová, R.; Macková, A.; Malinský, P.
2017-09-01
We have measured the electronic stopping powers of helium and lithium ions in the channelling direction of the Si〈1 0 0〉 crystal. The energy range used (2.0-8.0 MeV) was changed by 200 and 400-keV steps. The ratio α between the channelling and random stopping powers was determined as a function of the angle for 2, 3 and 4 MeV 4He+ ions and for 3 and 6 MeV 7Li+,2+ ions. The measurements were carried out using the Rutherford backscattering spectrometry in the channelling mode (RBS-C) in a silicon-on-insulator material. The experimental channelling stopping-power values measured in the channelling direction were then discussed in the frame of the random energy stopping predictions calculated using SRIM-2013 code and the theoretical unitary convolution approximation (UCA) model. The experimental channelling stopping-power values decrease with increasing ion energy. The stopping-power difference between channelled and randomly moving ions increases with the enhanced initial ion energy. The ratio between the channelling and random ion stopping powers α as a function of the ion beam incoming angle for 2, 3 and 4 MeV He+ ions and for 3 and 6 MeV Li+,2+ ions was observed in the range 0.5-1.
Nanofabrication with a helium ion microscope
NASA Astrophysics Data System (ADS)
Maas, Diederik; van Veldhoven, Emile; Chen, Ping; Sidorkin, Vadim; Salemink, Huub; van der Drift, Emile..; Alkemade, Paul
2010-03-01
The recently introduced helium ion microscope (HIM) is capable of imaging and fabrication of nanostructures thanks to its sub-nanometer sized ion probe. The unique interaction of the helium ions with the sample material provides very localized secondary electron emission, thus providing a valuable signal for high-resolution imaging as well as a mechanism for very precise nanofabrication. The low proximity effects, due to the low yield of backscattered ions and the confinement of the forward scattered ions into a narrow cone, enable patterning of ultra-dense sub-10 nm structures. This paper presents various nanofabrication results obtained with direct-write, with scanning helium ion beam lithography, and with helium ion beam induced deposition.
Joining of graphene flakes by low energy N ion beam irradiation
NASA Astrophysics Data System (ADS)
Wu, Xin; Zhao, Haiyan; Pei, Jiayun; Yan, Dong
2017-03-01
An approach utilizing low energy N ion beam irradiation is applied in joining two monolayer graphene flakes. Raman spectrometry and atomic force microscopy show the joining signal under 40 eV and 1 × 1014 cm-2 N ion irradiation. Molecular dynamics simulations demonstrate that the joining phenomenon is attributed to the punch-down effect and the subsequent chemical bond generation between the two sheets. The generated chemical bonds are made up of inserted ions (embedded joining) and knocked-out carbon atoms (saturation joining). The electronic transport properties of the joint are also calculated for its applications.
Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore
2001-01-01
The apparatus and method provide a technique for improving detection of alpha and/or beta emitting sources on items or in locations using indirect means. The emission forms generate ions in a medium surrounding the item or location and the medium is then moved to a detecting location where the ions are discharged to give a measure of the emission levels. To increase the level of ions generated and render the system particularly applicable for narrow pipes and other forms of conduits, the medium pressure is increased above atmospheric pressure. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Ionomer Design, Synthesis and Characterization for Ion-Conducting Energy Materials
NASA Astrophysics Data System (ADS)
Colby, Ralph H.
2013-03-01
For ionic actuators and battery separators, it is vital to utilize single-ion conductors that avoid the detrimental polarization of other ions; the commonly studied dual-ion conductors simply will not be used in the next generation of materials for these applications. Ab initio quantum chemistry calculations at 0 K in vacuum characterize ion interactions and ion solvation by various functional groups, allowing identification of constituents with weak interactions to be incorporated in ionomers for facile ion transport. Simple ideas for estimating the ion interactions and solvation at practical temperatures and dielectric constants are presented that indicate the rank ordering observed at 0 K in vacuum should be preserved. Hence, such ab initio calculations are useful for screening the plethora of combinations of polymer-ion, counterion and polar functional groups, to decide which are worthy of synthesis for new ionomers. Single-ion conducting ionomers are synthesized based on these calculations, with low glass transition temperatures (facile dynamics) to prepare ion-conducting membranes for ionic actuators and battery separators. Characterization by X-ray scattering, dielectric spectroscopy, NMR and linear viscoelasticity collectively develop a coherent picture of ionic aggregation and both counterion and polymer dynamics. Examples are shown of how ab initio calculations can be used to understand experimental observations of dielectric constant, glass transition temperature and conductivity of polymerized ionic liquids with counterions being either lithium, sodium, fluoride, hydroxide (for batteries) or bulky ionic liquids (for ionic actuators). This work was supported by the Department of Energy under Grant BES-DE-FG02-07ER46409.
Fabrication and demonstration of high energy density lithium ion microbatteries
NASA Astrophysics Data System (ADS)
Sun, Ke
Since their commercialization by Sony two decades ago, Li-ion batteries have only experienced mild improvement in energy and power performance, which remains one of the main hurdles for their widespread implementation in applications outside of powering compact portable devices, such as in electric vehicles. Li-ion batteries must be advanced through a disruptive technological development or a series of incremental improvements in chemistry and design in order to be competitive enough for advanced applications. As it will be introduced in this work, achieving this goal by new chemistries and chemical modifications does not seem to be promising in the short term, so efforts to fully optimize existing systems must be pursued at in parallel. This optimization must be mainly relying on the modification and optimizations of micro and macro structures of current battery systems. This kind of battery architecture study will be even more important when small energy storage devices are desired to power miniaturized and autonomous gadgets, such as MEMs, micro-robots, biomedical sensors, etc. In this regime, the limited space available makes requirements on electrode architecture more stringent and the assembly process more challenging. Therefore, the study of battery assembly strategies for Li-ion microbatteries will benefit not only micro-devices but also the development of more powerful and energetic large scale battery systems based on available chemistries. In chapter 2, preliminary research related to the mechanism for the improved rate capability of cathodes by amorphous lithium phosphate surficial films will be used to motivate the potential for structural optimization of existing commercial lithium ion battery electrode. In the following chapters, novel battery assembly techniques will be explored to achieve new battery architectures. In chapter 3, direct ink writing will be used to fabricate 3D interdigitated microbattery structures that have superior areal energy
NASA Astrophysics Data System (ADS)
Kubiček, K.; Mokler, P. H.; Mäckel, V.; Ullrich, J.; López-Urrutia, J. R. Crespo
2014-09-01
For the hydrogenlike Ar17+ ion, the 1s Lamb shift was absolutely determined with a 1.4% accuracy based on Lyman-α wavelength measurements that have negligible uncertainties from nuclear size effects. The result agrees with state-of-the-art quantum electrodynamics (QED) calculations, and demonstrates the suitability of Lyman-α transitions in highly charged ions as x-ray energy standards, accurate at the five parts-per-million level. For the heliumlike Ar16+ ion the transition energy for the 1s2p1P1→1s21S0 line was also absolutely determined on an even higher level of accuracy. Additionally, we present relative measurements of transitions in S15+,S14+, and Fe24+ ions. The data for the heliumlike S14+,Ar16+, and Fe24+ ions stringently confirm advanced bound-state QED predictions including screened QED terms that had recently been contested.
NASA Astrophysics Data System (ADS)
Lohmann, S.; Sortica, M. A.; Paneta, V.; Primetzhofer, D.
2018-02-01
We present a systematic analysis of the photon emission observed due to impact of pulsed keV ion beams in time-of-flight medium energy ion scattering (ToF-MEIS) experiments. Hereby, hydrogen, helium and neon ions served as projectiles and thin gold and titanium nitride films on different substrates were employed as target materials. The present experimental evidence indicates that a significant fraction of the photons has energies of around 10 eV, i.e. on the order of typical valence and conduction band transitions in solids. Furthermore, the scaling properties of the photon emission with respect to several experimental parameters were studied. A dependence of the photon yield on the projectile velocity was observed in all experiments. The photon yield exhibits a dependence on the film thickness and the scattering angle, which can be explained by photon production along the path of the incident ion through the material. Additionally, a strong dependence on the projectile type was found with the photon emission being higher for heavier projectiles. This difference is larger than the respective difference in electronic stopping cross section. The photon yield shows a strong material dependence, and according to a comparison of SiO2 and Si seems to be subject to matrix effects.
An extracellular enzyme synthesizes narrow-sized silver nanoparticles in both water and methanol
NASA Astrophysics Data System (ADS)
Rai, Tripti; Panda, Debashis
2015-03-01
Cellulase reduces silver ions in both aqueous and methanolic media yielding stable narrow-sized silver nanoparticles (Ag-NP) at room temperature. The synthesized nanoparticles have been characterized by various spectroscopic, microscopic methods. The redox potentials of tyrosine residues and protein backbone play an instrumental role to reduce the metal ions. The average size of nanoparticles formed in aqueous medium is of 5.04 ± 3.50 nm. Post-synthesis of Ag-NP secondary structure of enzyme is completely lost whereas upon incubation with chemically synthesized Ag-NP a significant gain in secondary structure is observed. Cellulase as a capping ligand stabilizes the silver nanoparticles even in methanol.
Monitoring Ion Implantation Energy Using Non-contact Characterization Methods
NASA Astrophysics Data System (ADS)
Tallian, M.; Pap, A.; Mocsar, K.; Somogyi, A.; Nadudvari, Gy.; Kosztka, D.; Pavelka, T.
2011-01-01
State-of-the-art ultra-shallow junctions are produced using extremely low ion implant energies, down to the range of 1-3 keV. This can be achieved by a variety of production techniques; however there is a significant risk that the actual implantation energy differs from the desired value. To detect this, sensitive measurement methods need to be utilized. Experiments show that both Photomodulated Reflection measurements before anneal and Junction Photovoltage-based sheet resistance measurements after anneal are suitable for this purpose.
Wang, Shijie; Wang, Rutao; Zhang, Yabin; Zhang, Li
2017-11-03
Carbon-based supercapacitors have attracted extensive attention as the complement to batteries, owing to their durable lifespan and superiority in high-power-demand fields. However, their widespread use is limited by the low energy storage density; thus, a high-surface-area porous carbon is urgently needed. Herein, a highly porous carbon with a Brunauer-Emmett-Teller specific surface area up to 3643 m 2 g -1 has been synthesized by chemical activation of papayas for the first time. This sp 2 -bonded porous carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form narrow mesopores of 2 ∼ 5 nm in width, which can be systematically tailored with varied activation levels. Two-electrode symmetric supercapacitors constructed by this porous carbon achieve energy density of 8.1 Wh kg -1 in aqueous electrolyte and 65.5 Wh kg -1 in ionic-liquid electrolyte. Furthermore, half-cells (versus Li or Na metal) using this porous carbon as ion sorption cathodes yield high specific capacity, e.g., 51.0 and 39.3 mAh g -1 in Li + and Na + based organic electrolyte. These results underline the possibility of obtaining the porous carbon for high-performance carbon-based supercapacitors and ion capacitors in a readily scalable and economical way.
NASA Astrophysics Data System (ADS)
Wang, Shijie; Wang, Rutao; Zhang, Yabin; Zhang, Li
2017-11-01
Carbon-based supercapacitors have attracted extensive attention as the complement to batteries, owing to their durable lifespan and superiority in high-power-demand fields. However, their widespread use is limited by the low energy storage density; thus, a high-surface-area porous carbon is urgently needed. Herein, a highly porous carbon with a Brunauer-Emmett-Teller specific surface area up to 3643 m2 g-1 has been synthesized by chemical activation of papayas for the first time. This sp2-bonded porous carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form narrow mesopores of 2 ˜ 5 nm in width, which can be systematically tailored with varied activation levels. Two-electrode symmetric supercapacitors constructed by this porous carbon achieve energy density of 8.1 Wh kg-1 in aqueous electrolyte and 65.5 Wh kg-1 in ionic-liquid electrolyte. Furthermore, half-cells (versus Li or Na metal) using this porous carbon as ion sorption cathodes yield high specific capacity, e.g., 51.0 and 39.3 mAh g-1 in Li+ and Na+ based organic electrolyte. These results underline the possibility of obtaining the porous carbon for high-performance carbon-based supercapacitors and ion capacitors in a readily scalable and economical way.
NASA Technical Reports Server (NTRS)
Halekas, Jasper S.; Poppe, A. R.; Delory, G. T.; Sarantos, M.; Farrell, W. M.; Angelopoulos, V.; McFadden, J. P.
2012-01-01
ARTEMIS observes pickup ions around the Moon, at distances of up to 20,000 km from the surface. The observed ions form a plume with a narrow spatial and angular extent, generally seen in a single energy/angle bin of the ESA instrument. Though ARTEMIS has no mass resolution capability, we can utilize the analytically describable characteristics of pickup ion trajectories to constrain the possible ion masses that can reach the spacecraft at the observation location in the correct energy/angle bin. We find that most of the observations are consistent with a mass range of approx. 20-45 amu, with a smaller fraction consistent with higher masses, and very few consistent with masses below 15 amu. With the assumption that the highest fluxes of pickup ions come from near the surface, the observations favor mass ranges of approx. 20-24 and approx. 36-40 amu. Although many of the observations have properties consistent with a surface or near-surface release of ions, some do not, suggesting that at least some of the observed ions have an exospheric source. Of all the proposed sources for ions and neutrals about the Moon, the pickup ion flux measured by ARTEMIS correlates best with the solar wind proton flux, indicating that sputtering plays a key role in either directly producing ions from the surface, or producing neutrals that subsequently become ionized.
Distinct dissociation kinetics between ion pairs: Solvent-coordinate free-energy landscape analysis.
Yonetani, Yoshiteru
2015-07-28
Different ion pairs exhibit different dissociation kinetics; however, while the nature of this process is vital for understanding various molecular systems, the underlying mechanism remains unclear. In this study, to examine the origin of different kinetic rate constants for this process, molecular dynamics simulations were conducted for LiCl, NaCl, KCl, and CsCl in water. The results showed substantial differences in dissociation rate constant, following the trend kLiCl < kNaCl < kKCl < kCsCl. Analysis of the free-energy landscape with a solvent reaction coordinate and subsequent rate component analysis showed that the differences in these rate constants arose predominantly from the variation in solvent-state distribution between the ion pairs. The formation of a water-bridging configuration, in which the water molecule binds to an anion and a cation simultaneously, was identified as a key step in this process: water-bridge formation lowers the related dissociation free-energy barrier, thereby increasing the probability of ion-pair dissociation. Consequently, a higher probability of water-bridge formation leads to a higher ion-pair dissociation rate.
NASA Astrophysics Data System (ADS)
Yuri, Yosuke; Narumi, Kazumasa; Yuyama, Takahiro
2016-08-01
The feasibility of the transverse intensity distribution measurement of low-energy (keV/u range) heavy-ion beams using radiochromic films is experimentally explored. We employ a Gafchromic radiochromic film, HD-V2, whose active layer is not laminated by a surface-protection layer. The coloration response of films irradiated with several ion beams is characterized in terms of optical density (OD) by reading the films with a general-purpose scanner. To explore the energy dependence of the film response widely, the kinetic energy of the beams is varied from 1.5 keV/u to 27 MeV/u. We have found that the coloration of HD-V2 films is induced by irradiation with low-energy ion beams of the order of 10 keV/u. The range of the beams is considerably shorter than the thickness of the film's active layer. The dependence of OD response on ion species is also discussed. We demonstrate that the Gafchromic film used here is useful for measuring the intensity distribution of such low-energy ion beams.
EBIT spectroscopy of highly charged heavy ions relevant to hot plasmas
NASA Astrophysics Data System (ADS)
Nakamura, Nobuyuki
2013-05-01
An electron beam ion trap (EBIT) is a versatile device for studying highly charged ions. We have been using two types of EBITs for the spectroscopic studies of highly charged ions. One is a high-energy device called the Tokyo-EBIT, and another is a compact low-energy device called CoBIT. Complementary use of them enables us to obtain spectroscopic data for ions over a wide charge-state range interacting with electrons over a wide energy range. In this talk, we present EBIT spectra of highly charged ions for tungsten, iron, bismuth, etc., which are relevant to hot plasmas. Tungsten is considered to be the main impurity in the ITER (the next generation nuclear fusion reactor) plasma, and thus its emission lines are important for diagnosing and controlling the ITER plasma. We have observed many previously unreported lines to supply the lack of spectroscopic data of tungsten ions. Iron is one of the main components of the solar corona, and its spectra are used to diagnose temperature, density, etc. The diagnostics is usually done by comparing observed spectra with model calculations. An EBIT can provide spectra under a well-defined condition; they are thus useful to test the model calculations. Laser-produced bismuth plasma is one of the candidates for a soft x-ray source in the water window region. An EBIT has a narrow charge state distribution; it is thus useful to disentangle the spectra of laser-produced plasma containing ions with a wide charge-state range. Performed with the support and under the auspices of the NIFS Collaboration Research program (NIFS09KOAJ003) and JSPS KAKENHI Number 23246165, and partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics.
Bulanov, S. S.; Esarey, E.; Schroeder, C. B.; ...
2015-03-13
Radiation Pressure Acceleration is a highly efficient mechanism of laser driven ion acceleration, with the laser energy almost totally transferrable to the ions in the relativistic regime. There is a fundamental limit on the maximum attainable ion energy, which is determined by the group velocity of the laser. In the case of a tightly focused laser pulses, which are utilized to get the highest intensity, another factor limiting the maximum ion energy comes into play, the transverse expansion of the target. Transverse expansion makes the target transparent for radiation, thus reducing the effectiveness of acceleration. Utilization of an external guidingmore » structure for the accelerating laser pulse may provide a way of compensating for the group velocity and transverse expansion effects.« less
Study of Biological Effects of Low Energy Ion Implantation on Tomato and Radish Breeding
NASA Astrophysics Data System (ADS)
Liang, Qiuxia; Huang, Qunce; Cao, Gangqiang; Ying, Fangqing; Liu, Yanbo; Huang, Wen
2008-04-01
Biological effects of 30 keV low energy nitrogen ion implantation on the seeds of five types of tomato and one type of radish were investigated. Results showed that low energy ions have different effects on different vegetables. The whole dose-response curve of the germination ratio did not take on "the shape of saddle", but was a rising and falling waveform with the increase or decrease in ion implantation. In the vegetable of Solanaceae, two outstanding aberrant plants were selected from M1 of Henan No.4 tomato at a dose of 7 × 1017 nitrogen ions/cm2, which had thin-leaves, long-petal and nipple tip fruit stably inherited to M7. Furthermore the analysis of the isozyme showed that the activity of the mutant tomato seedling was distinct in quantity and color. In Raphanus sativus L., the aberrances were obvious in the mutant of radish 791 at a dose of 5 × 1017 nitrogen ions/cm2, and the weight of succulent root and the volume of growth were over twice the control's. At present, many species for breeding have been identified in the field and only stable species have been selected for the experiment of production. It is evident that the low energy ion implantation technology has clear effects on vegetables' genetic improvement.
Trajectory analysis of low-energy and hyperthermal ions scattered from Cu(110)
DOE Office of Scientific and Technical Information (OSTI.GOV)
McEachern, R.L.; Goodstein, D.M.; Cooper, B.H.
1989-05-15
Trajectories of Na{sup +} ions scattered from the Cu(110) surface in the <1 1bar 0> and <001> azimuths were studied for a range of incident energies from 56 eV to 4 keV. The goal is to explain the trends observed in the energy spectra and determine what types of trajectories contribute to these spectra. Using the computer program SAFARI, simulations were performed with trajectory analyses for 100-, 200-, and 400-eV scattering. We show results from the 100-eV simulations in both azimuths and compare them with the experimental data. The simulated energy spectra are in excellent agreement with the data. Ionmore » trajectories and impact parameter plots from the simulations are used to determine the relative importance of different types of ion-surface-atom collisions. The simulations have shown that the striking differences observed in comparing the <1 1bar 0> and <001> spectra are mostly due to ions which scatter from second-layer atoms. This system exhibits strong focusing onto the second-layer atoms by the first-layer rows, and the focusing is very sensitive to the spacing between the rows. At the lower beam energies, scattering from the second layer dominates the measured spectra.« less
NASA Technical Reports Server (NTRS)
Roth, R. J.
1973-01-01
The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space and cause an isotropic energy distribution. When the distributions depart from Maxwellian, they are enhanced above the Maxwellian tail.
Dose Control System in the Optima XE Single Wafer High Energy Ion Implanter
DOE Office of Scientific and Technical Information (OSTI.GOV)
Satoh, Shu; Yoon, Jongyoon; David, Jonathan
2011-01-07
Photoresist outgassing can significantly compromise accurate dosimetry of high energy implants. High energy implant even at a modest beam current produces high beam powers which create significantly worse outgassing than low and medium energy implants and the outgassing continues throughout the implant due to the low dose in typical high energy implant recipes. In the previous generation of high energy implanters, dose correction by monitoring of process chamber pressure during photoresist outgassing has been used. However, as applications diversify and requirements change, the need arises for a more versatile photoresist correction system to match the versatility of a single wafermore » high energy ion implanter. We have successfully developed a new dosimetry system for the Optima XE single wafer high energy ion implanter which does not require any form of compensation due to the implant conditions. This paper describes the principles and performance of this new dose system.« less
Energy band gap and optical transition of metal ion modified double crossover DNA lattices.
Dugasani, Sreekantha Reddy; Ha, Taewoo; Gnapareddy, Bramaramba; Choi, Kyujin; Lee, Junwye; Kim, Byeonghoon; Kim, Jae Hoon; Park, Sung Ha
2014-10-22
We report on the energy band gap and optical transition of a series of divalent metal ion (Cu(2+), Ni(2+), Zn(2+), and Co(2+)) modified DNA (M-DNA) double crossover (DX) lattices fabricated on fused silica by the substrate-assisted growth (SAG) method. We demonstrate how the degree of coverage of the DX lattices is influenced by the DX monomer concentration and also analyze the band gaps of the M-DNA lattices. The energy band gap of the M-DNA, between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ranges from 4.67 to 4.98 eV as judged by optical transitions. Relative to the band gap of a pristine DNA molecule (4.69 eV), the band gap of the M-DNA lattices increases with metal ion doping up to a critical concentration and then decreases with further doping. Interestingly, except for the case of Ni(2+), the onset of the second absorption band shifts to a lower energy until a critical concentration and then shifts to a higher energy with further increasing the metal ion concentration, which is consistent with the evolution of electrical transport characteristics. Our results show that controllable metal ion doping is an effective method to tune the band gap energy of DNA-based nanostructures.
Use of low-energy hydrogen ion implants in high-efficiency crystalline-silicon solar cells
NASA Technical Reports Server (NTRS)
Fonash, S. J.; Sigh, R.; Mu, H. C.
1986-01-01
The use of low-energy hydrogen implants in the fabrication of high-efficiency crystalline silicon solar cells was investigated. Low-energy hydrogen implants result in hydrogen-caused effects in all three regions of a solar cell: emitter, space charge region, and base. In web, Czochralski (Cz), and floating zone (Fz) material, low-energy hydrogen implants reduced surface recombination velocity. In all three, the implants passivated the space charge region recombination centers. It was established that hydrogen implants can alter the diffusion properties of ion-implanted boron in silicon, but not ion-implated arsenic.
Heavy Ion Testing at the Galactic Cosmic Ray Energy Peak
NASA Technical Reports Server (NTRS)
Pellish, Jonathan A.; Xapsos, M. A.; LaBel, K. A.; Marshall, P. W.; Heidel, D. F.; Rodbell, K. P.; Hakey, M. C.; Dodd, P. E.; Shaneyfelt, M. R.; Schwank, J. R.;
2009-01-01
A 1 GeV/u Fe-56 Ion beam allows for true 90 deg. tilt irradiations of various microelectronic components and reveals relevant upset trends for an abundant element at the galactic cosmic ray (GCR) flux-energy peak.
NASA Astrophysics Data System (ADS)
Sartori, E.; Carozzi, G.; Veltri, P.; Spolaore, M.; Cavazzana, R.; Antoni, V.; Serianni, G.
2017-08-01
The measurement of the plasma potential and the energy spectrum of secondary particles in the drift region of a negative ion beam offers an insight into beam-induced plasma formation and beam transport in low pressure gasses. Plasma formation in negative-ion beam systems, and the characteristics of such a plasma are of interest especially for space charge compensation, plasma formation in neutralizers, and the development of improved schemes of beam-induced plasma neutralisers for future fusion devices. All these aspects have direct implications in the ITER Heating Neutral Beam and the operation of the prototypes, SPIDER and MITICA, and also have important role in the conceptual studies for NBI systems of DEMO, while at present experimental data are lacking. In this paper we present the design and development of an ion energy analyzer to measure the beam plasma formation and space charge compensation in negative ion beams. The diagnostic is a retarding field energy analyzer (RFEA), and will measure the transverse energy spectra of plasma molecular ions. The calculations that supported the design are reported, and a method to interpret the measurements in negative ion beam systems is also proposed. Finally, the experimental results of the first test in a magnetron plasma are presented.
Quantum fluctuations increase the self-diffusive motion of para-hydrogen in narrow carbon nanotubes.
Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester
2011-05-28
Quantum fluctuations significantly increase the self-diffusive motion of para-hydrogen adsorbed in narrow carbon nanotubes at 30 K comparing to its classical counterpart. Rigorous Feynman's path integral calculations reveal that self-diffusive motion of para-hydrogen in a narrow (6,6) carbon nanotube at 30 K and pore densities below ∼29 mmol cm(-3) is one order of magnitude faster than the classical counterpart. We find that the zero-point energy and tunneling significantly smoothed out the free energy landscape of para-hydrogen molecules adsorbed in a narrow (6,6) carbon nanotube. This promotes a delocalization of the confined para-hydrogen at 30 K (i.e., population of unclassical paths due to quantum effects). Contrary the self-diffusive motion of classical para-hydrogen molecules in a narrow (6,6) carbon nanotube at 30 K is very slow. This is because classical para-hydrogen molecules undergo highly correlated movement when their collision diameter approached the carbon nanotube size (i.e., anomalous diffusion in quasi-one dimensional pores). On the basis of current results we predict that narrow single-walled carbon nanotubes are promising nanoporous molecular sieves being able to separate para-hydrogen molecules from mixtures of classical particles at cryogenic temperatures. This journal is © the Owner Societies 2011
Benz, Mark G; Benz, Matthew W; Birnbaum, Steven B; Chason, Eric; Sheldon, Brian W; McGuire, Dale
2014-08-01
This feasibility study has shown that improved spatial resolution and reduced radiation dose can be achieved in pediatric CT by narrowing the X-ray photon energy spectrum. This is done by placing a hafnium filter between the X-ray generator and a pediatric abdominal phantom. A CT system manufactured in 1999 that was in the process of being remanufactured was used as the platform for this study. This system had the advantage of easy access to the X-ray generator for modifications to change the X-ray photon energy spectrum; it also had the disadvantage of not employing the latest post-imaging noise reduction iterative reconstruction technology. Because we observed improvements after changing the X-ray photon energy spectrum, we recommend a future study combining this change with an optimized iterative reconstruction noise reduction technique.
NASA Astrophysics Data System (ADS)
Mitani, K.; Seki, K.; Keika, K.; Gkioulidou, M.; Lanzerotti, L. J.; Mitchell, D. G.; Kletzing, C.
2017-12-01
It is known that proton is main contributor of the ring current and oxygen ions can make significant contribution during major magnetic storms. Ions are supplied to the ring current by radial transport from the plasma sheet. Convective transport of lower-energy protons and diffusive transport of higher-energy protons were reported to contribute to the storm-time and quiet-time ring current respectively [e.g., Gkioulidou et al., 2016]. However, supply mechanisms of the oxygen ions are not clear. To characterize the supply of oxygen ions to the ring current during magnetic storms, we studied the properties of energetic proton and oxygen ion phase space densities (PSDs) for specific magnetic moment (μ) during the April 23-25, 2013, geomagnetic storm observed by the Van Allen Probes mission. We here report on radial transport of high-energy (μ ≥ 0.5 keV/nT) oxygen ions into the deep inner magnetosphere during the late main phase of the magnetic storm. Since protons show little change during this period, this oxygen radial transport is inferred to cause the development of the late main phase. Enhancement of poloidal magnetic fluctuations is simultaneously observed. We estimated azimuthal mode number ≤5 by using cross wavelet analysis with ground-based observation of IMAGE ground magnetometers. The fluctuations can resonate with drift and bounce motions of the oxygen ions. The results suggest that combination of the drift and drift-bounce resonances is responsible for the radial transport of high-energy oxygen ions into the deep inner magnetosphere. We also report on the radial transport of the high-energy oxygen ions into the deep inner magnetosphere during other magnetic storms.
Measurements of ion stopping around the Bragg peak in high-energy-density plasmas
DOE Office of Scientific and Technical Information (OSTI.GOV)
Frenje, J. A.; Grabowski, P. E.; Li, C. K.
2015-11-09
For the first time, quantitative measurements of ion stopping at energies about the Bragg peak (or peak ion stopping, which occurs at an ion velocity comparable to the average thermal electron velocity), and its dependence on electron temperature (T e) and electron number density (n e) in the range of 0.5 – 4.0 keV and 3 × 10 22 – 3 × 10 23 cm -3 have been conducted, respectively. It is experimentally demonstrated that the position and amplitude of the Bragg peak varies strongly with T e with n e. As a result, the importance of including quantum diffractionmore » is also demonstrated in the stopping-power modeling of High-Energy-Density Plasmas.« less
LEICA - A low energy ion composition analyzer for the study of solar and magnetospheric heavy ions
NASA Technical Reports Server (NTRS)
Mason, Glenn M.; Hamilton, Douglas C.; Walpole, Peter H.; Heuerman, Karl F.; James, Tommy L.; Lennard, Michael H.; Mazur, Joseph E.
1993-01-01
The SAMPEX LEICA instrument is designed to measure about 0.5-5 MeV/nucleon solar and magnetospheric ions over the range from He to Ni. The instrument is a time-of-flight mass spectrometer which measures particle time-of-flight over an about 0.5 m path, and the residual energy deposited in an array of Si solid state detectors. Large area microchannel plates are used, resulting in a large geometrical factor for the instrument (0.6 sq cm sr) which is essential for accurate compositional measurements in small solar flares, and in studies of precipitating magnetospheric heavy ions.
NASA Astrophysics Data System (ADS)
Muramatsu, M.; Kitagawa, A.; Iwata, Y.; Hojo, S.; Sakamoto, Y.; Sato, S.; Ogawa, Hirotsugu; Yamada, S.; Ogawa, Hiroyuki; Yoshida, Y.; Ueda, T.; Miyazaki, H.; Drentje, A. G.
2008-11-01
Heavy-ion cancer treatment is being carried out at the Heavy Ion Medical Accelerator in Chiba (HIMAC) with 140 to 400 MeV/n carbon ions at National Institute of Radiological Sciences (NIRS) since 1994. At NIRS, more than 4,000 patients have been treated, and the clinical efficiency of carbon ion radiotherapy has been demonstrated for many diseases. A more compact accelerator facility for cancer therapy is now being constricted at the Gunma University. In order to reduce the size of the injector (consists of ion source, low-energy beam transport and post-accelerator Linac include these power supply and cooling system), an ion source requires production of highly charged carbon ions, lower electric power for easy installation of the source on a high-voltage platform, long lifetime and easy operation. A compact Electron Cyclotron Resonance Ion Source (ECRIS) with all permanent magnets is one of the best types for this purpose. An ECRIS has advantage for production of highly charged ions. A permanent magnet is suitable for reduce the electric power and cooling system. For this, a 10 GHz compact ECRIS with all permanent magnets (Kei2-source) was developed. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas-injection side, while the minimum B strength is 0.25 T. These parameters have been optimized for the production of C4+ based on experience at the 10 GHz NIRS-ECR ion source. The Kei2-source has a diameter of 320 mm and a length of 295 mm. The beam intensity of C4+ was obtained to be 618 eμA under an extraction voltage of 30 kV. Outline of the heavy ion therapy and development of the compact ion source for new facility are described in this paper.
A new high-energy cathode for a Na-ion battery with ultrahigh stability.
Park, Young-Uk; Seo, Dong-Hwa; Kwon, Hyung-Soon; Kim, Byoungkook; Kim, Jongsoon; Kim, Haegyeom; Kim, Inkyung; Yoo, Han-Ill; Kang, Kisuk
2013-09-18
Large-scale electric energy storage is a key enabler for the use of renewable energy. Recently, the room-temperature Na-ion battery has been rehighlighted as an alternative low-cost technology for this application. However, significant challenges such as energy density and long-term stability must be addressed. Herein, we introduce a novel cathode material, Na1.5VPO4.8F0.7, for Na-ion batteries. This new material provides an energy density of ~600 Wh kg(-1), the highest value among cathodes, originating from both the multielectron redox reaction (1.2 e(-) per formula unit) and the high potential (~3.8 V vs Na(+)/Na) of the tailored vanadium redox couple (V(3.8+)/V(5+)). Furthermore, an outstanding cycle life (~95% capacity retention for 100 cycles and ~84% for extended 500 cycles) could be achieved, which we attribute to the small volume change (2.9%) upon cycling, the smallest volume change among known Na intercalation cathodes. The open crystal framework with two-dimensional Na diffusional pathways leads to low activation barriers for Na diffusion, enabling excellent rate capability. We believe that this new material can bring the low-cost room-temperature Na-ion battery a step closer to a sustainable large-scale energy storage system.
The stopping power and energy straggling of light ions in graphene oxide foils
NASA Astrophysics Data System (ADS)
Mikšová, R.; Macková, A.; Malinský, P.; Sofer, Z.
2017-09-01
Energy-loss and straggling experiments were performed using 2-4 MeV 1H+ and 7.4-9.0 MeV 4He2+ ions in graphene oxide foils by the transmission technique. The thickness of the graphene oxide foils was determined using a detailed image analysis of a graphene oxide cut, which was used to refine the graphene oxide density. The density was determined by the standard technique of micro-balance weighing. The stoichiometry of the graphene oxide foils before the irradiation was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA) using 2 and 2.5 MeV 4He+. The measured energy stopping powers for hydrogen and helium ions in graphene oxide were compared with the predictions obtained from the SRIM-2013 code. The energy straggling was compared with that calculated using Bohr's, Bethe-Livingston and Yang predictions. The results show that the stopping power of graphene oxide foils irradiated by both ion species decreases with increasing energies, the differences between the measured and predicted values being below 3.8%. The energy straggling determined in our experiment is higher than Bohr's and Bethe-Livingston predicted values; the predictions by Yang are in better agreement with our experiment.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jiménez, José A., E-mail: jose.jimenez@unf.edu; Sendova, Mariana
2014-07-21
Optimizing the efficiency of Er{sup 3+} emission in the near-infrared telecommunication window in glass matrices is currently a subject of great interest in photonics research. In this work, Cu{sup +} ions are shown to be successfully stabilized at a high concentration in Er-containing phosphate glass by a single-step melt-quench method, and demonstrated to transfer energy to Er{sup 3+} thereby enhancing the near-infrared emission about 15 times. The spectroscopic data indicate an energy conversion process where Cu{sup +} ions first absorb photons broadly around 360 nm and subsequently transfer energy from the Stokes-shifted emitting states to resonant Er{sup 3+} absorption transitions inmore » the visible. Consequently, the Er{sup 3+} electronic excited states decay and the {sup 4}I{sub 3/2} metastable state is populated, leading to the enhanced emission at 1.53 μm. Monovalent copper ions are thus recognized as sensitizers of Er{sup 3+} ions, suggesting the potential of Cu{sup +} co-doping for applications in the telecommunications, solar cells, and solid-state lasing realizable under broad band near-ultraviolet optical pumping.« less
Galaxy properties from J-PAS narrow-band photometry
NASA Astrophysics Data System (ADS)
Mejía-Narváez, A.; Bruzual, G.; Magris, C. G.; Alcaniz, J. S.; Benítez, N.; Carneiro, S.; Cenarro, A. J.; Cristóbal-Hornillos, D.; Dupke, R.; Ederoclite, A.; Marín-Franch, A.; de Oliveira, C. Mendes; Moles, M.; Sodre, L.; Taylor, K.; Varela, J.; Ramió, H. Vázquez
2017-11-01
We study the consistency of the physical properties of galaxies retrieved from spectral energy distribution (SED) fitting as a function of spectral resolution and signal-to-noise ratio (SNR). Using a selection of physically motivated star formation histories, we set up a control sample of mock galaxy spectra representing observations of the local Universe in high-resolution spectroscopy, and in 56 narrow-band and 5 broad-band photometry. We fit the SEDs at these spectral resolutions and compute their corresponding stellar mass, the mass- and luminosity-weighted age and metallicity, and the dust extinction. We study the biases, correlations and degeneracies affecting the retrieved parameters and explore the role of the spectral resolution and the SNR in regulating these degeneracies. We find that narrow-band photometry and spectroscopy yield similar trends in the physical properties derived, the former being considerably more precise. Using a galaxy sample from the Sloan Digital Sky Survey (SDSS), we compare more realistically the results obtained from high-resolution and narrow-band SEDs (synthesized from the same SDSS spectra) following the same spectral fitting procedures. We use results from the literature as a benchmark to our spectroscopic estimates and show that the prior probability distribution functions, commonly adopted in parametric methods, may introduce biases not accounted for in a Bayesian framework. We conclude that narrow-band photometry yields the same trend in the age-metallicity relation in the literature, provided it is affected by the same biases as spectroscopy, albeit the precision achieved with the latter is generally twice as large as with the narrow-band, at SNR values typical of the different kinds of data.
Quightness: A proposed figure of merit for sources of low-energy, high-charge-state ions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schmieder, R.W.
A variety of ion sources, including the EBIS and ECRIS, are distinguished by their ability to produce low-energy ions of very high charge state. It would be useful to have some figure of merit that is particularly sensitive to this performance. I propose here such a quantity, called Quightness,'' which is related to brightness but which enhances the contrast between sources supplying multicharged ions of low energy. The rationale for introducing this quantity, its etymology and relationship to other figures of merit, and some representative values are presented.
Tajparast, Mohammad; Glavinović, Mladen I
2018-06-06
Bio-membranes as capacitors store electric energy, but their permittivity is low whereas the permittivity of surrounding solution is high. To evaluate the effective capacitance of the membrane/solution system and determine the electric energy stored within the membrane and in the solution, we estimated their electric variables using Poisson-Nernst-Planck simulations. We calculated membrane and solution capacitances from stored electric energy. The effective capacitance was calculated by fitting a six-capacitance model to charges (fixed and ion) and associated potentials, because it cannot be considered as a result of membrane and solution capacitance in series. The electric energy stored within the membrane (typically much smaller than that in the solution), depends on the membrane permittivity, but also on the external electric field, surface charge density, water permittivity and ion concentration. The effect on capacitances is more specific. Solution capacitance rises with greater solution permittivity or ion concentration, but the membrane capacitance (much smaller than solution capacitance) is only influenced by its permittivity. Interestingly, the effective capacitance is independent of membrane or solution permittivity, but rises as the ion concentration increases and surface charge becomes positive. Experimental estimates of membrane capacitance are thus not necessarily a reliable index of its surface area. Copyright © 2018. Published by Elsevier B.V.
NASA Astrophysics Data System (ADS)
Bharti, Madhu Lata; Singh, Fouran; Ramola, R. C.; Joshi, Veena
2017-11-01
The self-standing films of non-conducting polymethyl methacrylate (PMMA) were irradiated in vacuum using high energy light ions (HELIs) of 50 MeV Lithium (Li+3) and 80 MeV Carbon (C+5) at various ion dose to induce the optical changes in the films. Upon HELI irradiation, films exhibit a significant enhancement in optical reflectivity at the highest dose. Interestingly, the photoluminescence (PL) emission band with green light at (514.5 nm) shows a noticeable increase in the intensity with increasing ion dose for both ions. However, the rate of increase in PL intensity is different for both HELI and can be correlated with the linear energy transfer by these ions in the films. Origin of PL is attributed to the formation of carbon cluster and hydrogenated amorphous carbon in the polymer films. HAC clusters act as PL active centres with optical reflectivity. Most of the harmful radiation like UV are absorbed by the material and is becoming opaque after irradiation and this PL active material are useful in fabrication of optoelectronic devices, UV-filter, back-lit components in liquid crystal display systems, micro-components for integrate optical circuits, diffractive elements, advanced materials and are also applicable to the post irradiation laser treatment by means of ion irradiation.
NASA Astrophysics Data System (ADS)
Shevkunov, S. V.
2017-11-01
The mean force potential (MFP) of interaction between counterions Na+ and Cl- in a planar nanopore with structureless hydrophobic walls is calculated via computer simulation under the condition that the nanopore is in contact with water at an external pressure that exceeds the saturation pressure but remains insufficient to fill the nanopore with water. For a nanopore with a liquid phase, the MFP dependence on the interionic distance indicates the dissociation of an ion pair into two hydrated ions in a nanopore that is not completely filled with water. Fluctuations in the number of water molecules drawn into the interionic space decisively influence the dissociation. The attraction between counterions, averaged over thermal fluctuations, depends largely on the pore width and grows as the shielding of the ions' electric field by water molecules in a narrow pore diminishes. The contributions from energy and entropy to the free energy of hydration are analyzed.
Precise energy eigenvalues of hydrogen-like ion moving in quantum plasmas
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dutta, S.; Saha, Jayanta K.; Mukherjee, T. K.
2015-06-15
The analytic form of the electrostatic potential felt by a slowly moving test charge in quantum plasma is developed. It has been shown that the electrostatic potential is composed of two parts: the Debye-Huckel screening term and the near-field wake potential. The latter depends on the velocity of the test charge as well as on the number density of the plasma electrons. Rayleigh-Ritz variational calculation has been done to estimate precise energy eigenvalues of hydrogen-like carbon ion under such plasma environment. A detailed analysis shows that the energy levels gradually move to the continuum with increasing plasma electron density whilemore » the level crossing phenomenon has been observed with the variation of ion velocity.« less
NASA Technical Reports Server (NTRS)
Kwong, Victor H. S.
1996-01-01
Charge transfer at electron-volt energies between multiply charged atomic ions and neutral atoms and molecules is of considerable importance in astrophysics, plasma physics, and in particular, fusion plasmas. In the year covered by this report, several major tasks were completed. These include: (1) the re-calibration of the ion gauge to measure the absolute particle densities of H2, He, N2, and CO for our current measurements; (2) the analysis of data for charge transfer reactions of N(exp 2 plus) ion and He, H2, N2, and CO; (3) measurement and data analysis of the charge transfer reaction of (Fe(exp 2 plus) ion and H2; (4) charge transfer measurement of Fe(exp 2 plus) ion and H2; and (5) redesign and modification of the ion detection and data acquisition system for the low energy beam facility (reflection time of flight mass spectrometer) dedicated to the study of state select charge transfer.
Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation
2013-01-01
We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer. PMID:24138985
Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation.
Attri, Asha; Kumar, Ajit; Verma, Shammi; Ojha, Sunil; Asokan, Kandasami; Nair, Lekha
2013-10-18
We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer.
Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation
NASA Astrophysics Data System (ADS)
Attri, Asha; Kumar, Ajit; Verma, Shammi; Ojha, Sunil; Asokan, Kandasami; Nair, Lekha
2013-10-01
We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer.
Energy dissipation on ion-accelerator grids during high-voltage breakdown
DOE Office of Scientific and Technical Information (OSTI.GOV)
Menon, M.M.; Ponte, N.S.
1981-01-01
The effects of stored energy in the system capacitance across the accelerator grids during high voltage vacuum breakdown are examined. Measurements were made of the current flow and the energy deposition on the grids during breakdown. It is shown that only a portion (less than or equal to 40 J) of the total stored energy (congruent to 100 J) is actually dissipated on the grids. Most of the energy is released during the formation phase of the vacuum arc and is deposited primarily on the most positive grid. Certain abnormal situations led to energy depositions of about 200 J onmore » the grid, but the ion accelerator endured them without exhibiting any deterioration in performance.« less
Investigation on target normal sheath acceleration through measurements of ions energy distribution
DOE Office of Scientific and Technical Information (OSTI.GOV)
Tudisco, S., E-mail: tudisco@lns.infn.it; Cirrone, G. A. P.; Mascali, D.
2016-02-15
An experimental campaign aiming at investigating the ion acceleration mechanisms through laser-matter interaction in femtosecond domain has been carried out at the Intense Laser Irradiation Laboratory facility with a laser intensity of up to 2 × 10{sup 19} W/cm{sup 2}. A Thomson parabola spectrometer was used to obtain the spectra of the ions of the different species accelerated. Here, we show the energy spectra of light-ions and we discuss their dependence on structural characteristics of the target and the role of surface and target bulk in the acceleration process.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sobolewski, Mark A.; Wang, Yicheng; Goyette, Amanda
2016-07-11
Simple kinematic considerations indicate that, under certain conditions in radio-frequency (rf) plasmas, the amplitude of the low-energy peak in ion energy distributions (IEDs) measured at an electrode depends sensitively on ion velocities upstream, at the presheath/sheath boundary. By measuring this amplitude, the velocities at which ions exit the presheath can be determined and long-standing controversies regarding presheath transport can be resolved. Here, IEDs measured in rf-biased, inductively coupled plasmas in CF{sub 4} gas determined the presheath exit velocities of all significant positive ions: CF{sub 3}{sup +}, CF{sub 2}{sup +}, CF{sup +}, and F{sup +}. At higher bias voltages, we detectedmore » essentially the same velocity for all four ions. For all ions, measured velocities were significantly lower than the Bohm velocity and the electropositive ion sound speed. Neither is an accurate boundary condition for rf sheaths in electronegative gases: under certain low-frequency, high-voltage criteria defined here, either yields large errors in predicted IEDs. These results indicate that many widely used sheath models will need to be revised.« less
NASA Astrophysics Data System (ADS)
Reitsma, G.; Zettergren, H.; Boschman, L.; Bodewits, E.; Hoekstra, R.; Schlathölter, T.
2013-12-01
We report on 30 keV He2 + collisions with naphthalene (C10H8) molecules, which leads to very extensive fragmentation. To unravel such complex fragmentation patterns, we designed and constructed an experimental setup, which allows for the determination of the full momentum vector by measuring charged collision products in coincidence in a recoil ion momentum spectrometer type of detection scheme. The determination of fragment kinetic energies is found to be considerably more accurate than for the case of mere coincidence time-of-flight spectrometers. In fission reactions involving two cationic fragments, typically kinetic energy releases of 2-3 eV are observed. The results are interpreted by means of density functional theory calculations of the reverse barriers. It is concluded that naphthalene fragmentation by collisions with keV ions clearly is much more violent than the corresponding photofragmentation with energetic photons. The ion-induced naphthalene fragmentation provides a feedstock of various small hydrocarbonic species of different charge states and kinetic energy, which could influence several molecule formation processes in the cold interstellar medium and facilitates growth of small hydrocarbon species on pre-existing polycyclic aromatic hydrocarbons.
Quadrupole terms in the Maxwell equations: Born energy, partial molar volume, and entropy of ions.
Slavchov, Radomir I; Ivanov, Tzanko I
2014-02-21
A new equation of state relating the macroscopic quadrupole moment density Q to the gradient of the field ∇E in an isotropic fluid is derived: Q = αQ(∇E - U∇·E/3), where the quadrupolarizability αQ is proportional to the squared molecular quadrupole moment. Using this equation of state, a generalized expression for the Born energy of an ion dissolved in quadrupolar solvent is obtained. It turns out that the potential and the energy of a point charge in a quadrupolar medium are finite. From the obtained Born energy, the partial molar volume and the partial molar entropy of a dissolved ion follow. Both are compared to experimental data for a large number of simple ions in aqueous solutions. From the comparison the value of the quadrupolar length LQ is determined, LQ = (αQ/3ɛ)(1/2) = 1-4 Å. Data for ion transfer from aqueous to polar oil solution are analyzed, which allowed for the determination of the quadrupolarizability of nitrobenzene.
NASA Astrophysics Data System (ADS)
Pollard, Travis P.; Beck, Thomas L.
2018-06-01
Attempts to establish an absolute single-ion hydration free energy scale have followed multiple strategies. Two central themes consist of (1) employing bulk pair thermodynamic data and an underlying interfacial-potential-free model to partition the hydration free energy into individual contributions [Marcus, Latimer, and tetraphenyl-arsonium/tetraphenyl-borate (TATB) methods] or (2) utilizing bulk thermodynamic and cluster data to estimate the free energy to insert a proton into water, including in principle an interfacial potential contribution [the cluster pair approximation (CPA)]. While the results for the hydration free energy of the proton agree remarkably well between the three approaches in the first category, the value differs from the CPA result by roughly +10 kcal/mol, implying a value for the effective electrochemical surface potential of water of -0.4 V. This paper provides a computational re-analysis of the TATB method for single-ion free energies using quasichemical theory. A previous study indicated a significant discrepancy between the free energies of hydration for the TA cation and the TB anion. We show that the main contribution to this large computed difference is an electrostatic artifact arising from modeling interactions in periodic boundaries. No attempt is made here to develop more accurate models for the local ion/solvent interactions that may lead to further small free energy differences between the TA and TB ions, but the results clarify the primary importance of interfacial potential effects for analysis of the various free energy scales. Results are also presented, related to the TATB assumption in the organic solvents dimethyl sulfoxide and 1,2-dichloroethane.
Charge exchange of highly charged argon ions as a function of projectile energy
NASA Astrophysics Data System (ADS)
Allen, F. I.; Biedermann, C.; Radtke, R.; Fussmann, G.
2007-03-01
X-ray emission of highly charged argon ions following charge exchange collisions with argon atoms has been measured as a function of projectile energy. The ions are extracted from the Electron Beam Ion Trap (EBIT) in Berlin and selected according to their massto-charge ratios. Experiments focussed on hydrogen-like and bare argon ions which were decelerated from 125q eV/amu to below 0.25q eV/amu prior to interaction with an argon gas target. The x-ray spectra recorded probe the cascading transitions resulting from electron capture into Rydberg states and are found to vary significantly with collision velocity. This indicates a shift in the orbital angular momentum of the capture state. Hardness ratios are observed to increase with decreasing projectile energy though at a rate which differs from the results of simulations. For comparison, measurements of the x-ray emission following charge exchange within the trap were carried out and are in agreement with the findings of the EBIT group at LLNL. Both of these in situ measurements, however, are in discrepancy with the results of the experiments using extracted ions.
Pressure Fluctuation Characteristics of Narrow Gauge Train Running Through Tunnel
NASA Astrophysics Data System (ADS)
Suzuki, Masahiro; Sakuma, Yutaka
Pressure fluctuations on the sides of narrow (1067 mm) gauge trains running in tunnels are measured for the first time to investigate the aerodynamic force acting on the trains. The present measurements are compared with earlier measurements obtained with the Shinkansen trains. The results are as follows: (1) The aerodynamic force, which stems from pressure fluctuations on the sides of cars, puts the energy into the vibration of the car body running through a tunnel. (2) While the pressure fluctuations appear only on one of the two sides of the trains running in double-track tunnels, the fluctuations in opposite phase on both sides in single-track tunnels. (3) The on-track test data of the narrow gauge trains show the same tendency as those of the Shinkansen trains, although it is suggested that the pressure fluctuations develop faster along the narrow gauge trains than the Shinkansen trains.
NASA Astrophysics Data System (ADS)
Suyama, Taku; Bae, Hansin; Setaka, Kenta; Ogawa, Hayato; Fukuoka, Yushi; Suzuki, Haruka; Toyoda, Hirotaka
2017-11-01
O- ion flux from the indium tin oxide (ITO) sputter target under Ar ion bombardment is quantitatively evaluated using a calorimetry method. Using a mass spectrometer with an energy analyzer, O- energy distribution is measured with spatial dependence. Directional high-energy O- ion ejected from the target surface is observed. Using a calorimetry method, localized heat flux originated from high-energy O- ion is measured. From absolute evaluation of the heat flux from O- ion, O- particle flux in order of 1018 m-2 s-1 is evaluated at a distance of 10 cm from the target. Production yield of O- ion on the ITO target by one Ar+ ion impingement at a kinetic energy of 244 eV is estimated to be 3.3 × 10-3 as the minimum value.
Energy loss of ions by electric-field fluctuations in a magnetized plasma.
Nersisyan, Hrachya B; Deutsch, Claude
2011-06-01
The results of a theoretical investigation of the energy loss of charged particles in a magnetized classical plasma due to the electric-field fluctuations are reported. The energy loss for a test particle is calculated through the linear-response theory. At vanishing magnetic field, the electric-field fluctuations lead to an energy gain of the charged particle for all velocities. It has been shown that in the presence of strong magnetic field, this effect occurs only at low velocities. In the case of high velocities, the test particle systematically loses its energy due to the interaction with a stochastic electric field. The net effect of the fluctuations is the systematic reduction of the total energy loss (i.e., the sum of the polarization and stochastic energy losses) at vanishing magnetic field and reduction or enhancement at strong field, depending on the velocity of the particle. It is found that the energy loss of the slow heavy ion contains an anomalous term that depends logarithmically on the projectile mass. The physical origin of this anomalous term is the coupling between the cyclotron motion of the plasma electrons and the long-wavelength, low-frequency fluctuations produced by the projectile ion. This effect may strongly enhance the stochastic energy gain of the particle.
The role of ion-exchange membrane in energy conversion
NASA Astrophysics Data System (ADS)
Khoiruddin, Aryanti, Putu T. P.; Hakim, Ahmad N.; Wenten, I. Gede
2017-05-01
Ion-exchange membrane (IEM) may play an important role in the future of electrical energy generation which is considered as renewable and clean energy. Fell cell (FC) is one of the promising technologies for solving energy issues in the future owing to the interesting features such as high electrical efficiency, low emissions, low noise level, and modularity. IEM-based processes, such as microbial fuel cell (MFC) and reverse electrodialysis (RED) may be combined with water or wastewater treatment into an integrated system. By using the integrated system, water and energy could be produced simultaneously. The IEM-based processes can be used for direct electricity generation or long term energy storage such as by harnessing surplus electricity from an existing renewable energy system to be converted into hydrogen gas via electrolysis or stored into chemical energy via redox flow battery (RFB). In this paper, recent development and applications of IEM-based processes in energy conversion are reviewed. In addition, perspective and challenges of IEM-based processes in energy conversion are pointed out.
Ion specific effects: decoupling ion-ion and ion-water interactions
Song, Jinsuk; Kang, Tae Hui; Kim, Mahn Won; Han, Songi
2015-01-01
energy values derived from experimental data for various ions are compared with theoretical values in the literature. Ultimately, quantifying ion-induced changes in surface energy for the purpose of developing valid theoretical models for ion-water interaction, will be critical to rationalizing the Hofmeister effect. PMID:25761273
Surface-conductivity enhancement of PMMA by keV-energy metal-ion implantation
NASA Astrophysics Data System (ADS)
Bannister, M. E.; Hijazi, H.; Meyer, H. M.; Cianciolo, V.; Meyer, F. W.
2014-11-01
An experiment has been proposed to measure the neutron electric dipole moment (nEDM) with high precision at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source. One of the requirements of this experiment is the development of PMMA (Lucite) material with a sufficiently conductive surface to permit its use as a high-voltage electrode while immersed in liquid He. At the ORNL Multicharged Ion Research Facility, an R&D activity is under way to achieve suitable surface conductivity in poly-methyl methacrylate (PMMA) using metal ion implantation. The metal implantation is performed using an electron-cyclotron-resonance (ECR) ion source and a recently developed beam line deceleration module that is capable of providing high flux beams for implantation at energies as low as a few tens of eV. The latter is essential for reaching implantation fluences exceeding 1 × 1016 cm-2, where typical percolation thresholds in polymers have been reported. In this contribution, we report results on initial implantation of Lucite by Ti and W beams with keV energies to average fluences in the range 0.5-6.2 × 1016 cm-2. Initial measurements of surface-resistivity changes are reported as function of implantation fluence, energy, and sample temperature. We also report X-ray photoelectron spectroscopy (XPS) surface and depth profiling measurements of the ion implanted samples, to identify possible correlations between the near surface and depth resolved implanted W concentrations and the measured surface resistivities.
Nano-ranged low-energy ion-beam-induced DNA transfer in biological cells
NASA Astrophysics Data System (ADS)
Yu, L. D.; Wongkham, W.; Prakrajang, K.; Sangwijit, K.; Inthanon, K.; Thongkumkoon, P.; Wanichapichart, P.; Anuntalabhochai, S.
2013-06-01
Low-energy ion beams at a few tens of keV were demonstrated to be able to induce exogenous macromolecules to transfer into plant and bacterial cells. In the process, the ion beam with well controlled energy and fluence bombarded living cells to cause certain degree damage in the cell envelope in nanoscales to facilitate the macromolecules such as DNA to pass through the cell envelope and enter the cell. Consequently, the technique was applied for manipulating positive improvements in the biological species. This physical DNA transfer method was highly efficient and had less risk of side-effects compared with chemical and biological methods. For better understanding of mechanisms involved in the process, a systematic study on the mechanisms was carried out. Applications of the technique were also expanded from DNA transfer in plant and bacterial cells to DNA transfection in human cancer cells potentially for the stem cell therapy purpose. Low-energy nitrogen and argon ion beams that were applied in our experiments had ranges of 100 nm or less in the cell envelope membrane which was majorly composed of polymeric cellulose. The ion beam bombardment caused chain-scission dominant damage in the polymer and electrical property changes such as increase in the impedance in the envelope membrane. These nano-modifications of the cell envelope eventually enhanced the permeability of the envelope membrane to favor the DNA transfer. The paper reports details of our research in this direction.
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.
NASA Astrophysics Data System (ADS)
Suzuki, T. T.; Sakai, O.
2017-04-01
Surface magnetism is analyzed by spin-dependent He+-ion neutralization (the Auger neutralization) in the vicinity of a surface using an electron spin-polarized low-energy He+-ion beam [spin-polarized ion scattering spectroscopy (SP-ISS)]. Recently, spin-orbit coupling (SOC) has been found to act as another mechanism of spin-dependent low-energy He+-ion scattering. Thus, it is crucial for surface magnetism analyses by SP-ISS to separate those two mechanisms. In the present study, we investigated the spin-induced asymmetry in scattering of low-energy He+ ions on ultrathin Au and Sn films as well as the oxygen adsorbate on a magnetized-Fe(100) surface where these two mechanisms may coexist. We found that the Fe surface magnetism immediately disappeared with the growth of those overlayers. On the other hand, we observed no induced spin polarization in the Au and Sn thin films even in the very initial stage of the growth. We also observed that the spin asymmetry of the O adsorbate was induced by the magnetism of the underlying Fe substrate. The present study demonstrates that the two mechanisms of the spin-asymmetric He+-ion scattering (the ion neutralization and SOC) can be separated by an azimuthal-angle-resolved SP-ISS measurement.
NASA Astrophysics Data System (ADS)
Peters, Jens F.; Weil, Marcel
2017-10-01
Aqueous hybrid ion batteries (AHIB) are being promoted as an environmentally friendly alternative to existing stationary battery technologies. However, no quantification of their potential environmental impacts has yet been done. This paper presents a prospective life cycle assessment of an AHIB module and compares its performance with lithium-ion and sodium-ion batteries in two different stationary energy storage applications. The findings show that the claim of being an environmentally friendly technology can only be supported with some major limitations. While the AHIB uses abundant and non-toxic materials, it has a very low energy density and requires increased amounts of material for providing a given storage capacity. Per kWh of battery, results comparable to those of the alternative lithium- or sodium-ion batteries are obtained, but significantly higher impacts under global warming and ozone depletion aspects. The comparable high cycle life of the AHIB compensates this partially, requiring less battery replacements over the lifetime of the application. On the other hand, its internal inefficiencies are higher, what becomes the dominating factor when charging majorly fossil based electricity, making AHIB unattractive for this type of applications.
Free-energy relationships in ion channels activated by voltage and ligand
Chowdhury, Sandipan
2013-01-01
Many ion channels are modulated by multiple stimuli, which allow them to integrate a variety of cellular signals and precisely respond to physiological needs. Understanding how these different signaling pathways interact has been a challenge in part because of the complexity of underlying models. In this study, we analyzed the energetic relationships in polymodal ion channels using linkage principles. We first show that in proteins dually modulated by voltage and ligand, the net free-energy change can be obtained by measuring the charge-voltage (Q-V) relationship in zero ligand condition and the ligand binding curve at highly depolarizing membrane voltages. Next, we show that the voltage-dependent changes in ligand occupancy of the protein can be directly obtained by measuring the Q-V curves at multiple ligand concentrations. When a single reference ligand binding curve is available, this relationship allows us to reconstruct ligand binding curves at different voltages. More significantly, we establish that the shift of the Q-V curve between zero and saturating ligand concentration is a direct estimate of the interaction energy between the ligand- and voltage-dependent pathway. These free-energy relationships were tested by numerical simulations of a detailed gating model of the BK channel. Furthermore, as a proof of principle, we estimate the interaction energy between the ligand binding and voltage-dependent pathways for HCN2 channels whose ligand binding curves at various voltages are available. These emerging principles will be useful for high-throughput mutagenesis studies aimed at identifying interaction pathways between various regulatory domains in a polymodal ion channel. PMID:23250866
Ionomers for Ion-Conducting Energy Materials
NASA Astrophysics Data System (ADS)
Colby, Ralph
For ionic actuators and battery separators, it is vital to utilize single-ion conducting ionomers that avoid the detrimental polarization of other ions. Single-ion conducting ionomers are synthesized based on DFT calculations, with low glass transition temperatures (facile dynamics) to prepare ion-conducting membranes for battery separators that conduct Li+ or Na+. Characterization by X-ray scattering, dielectric spectroscopy, FTIR, NMR and linear viscoelasticity collectively develop a coherent picture of ionic aggregation and both counterion and polymer dynamics. 7Li NMR diffusion measurements find that diffusion is faster than expected by conductivity using the Nernst-Einstein equation, which means that the majority of Li diffusion occurs by ion pairs moving with the polymer segmental motion. Segmental motion only contributes to ionic conduction in the rare event that one of these ion pairs has an extra Li (a positive triple ion). This leads us to a new metric for ion-conducting soft materials, the product of the cation number density p0 and their diffusion coefficient D; p0D is the diffusive flux of lithium ions. This new metric has a maximum at intermediate ion content that corresponds to the overlap of ion pair polarizability volumes. At higher ion contents, the ion pairs interact strongly and form larger aggregation states that retard segmental motion of both mobile ion pairs and triple ions.
Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves
NASA Technical Reports Server (NTRS)
Thorne, Richard M.; Horne, Richard B.
1994-01-01
Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.
Leung, K.N.; Ehlers, K.W.
1982-05-04
A magnetic filter for an ion source reduces the production of undesired ion species and improves the ion beam quality. High-energy ionizing electrons are confined by the magnetic filter to an ion source region, where the high-energy electrons ionize gas molecules. One embodiment of the magnetic filter uses permanent magnets oriented to establish a magnetic field transverse to the direction of travel of ions from the ion source region to the ion extraction region. In another embodiment, low energy 16 eV electrons are injected into the ion source to dissociate gas molecules and undesired ion species into desired ion species,
NARROW-GAP POINT-TO-PLANE CORONA WITH HIGH VELOCITY FLOWS
The article discusses a mathematical model developed to describe a narrow- gap point- to- plane corona system used in the detoxification of chemical agents or their simulants, for which the degree of destruction depends on the strength of the electric field or electron energy. Na...
A review on the key issues for lithium-ion battery management in electric vehicles
NASA Astrophysics Data System (ADS)
Lu, Languang; Han, Xuebing; Li, Jianqiu; Hua, Jianfeng; Ouyang, Minggao
2013-03-01
Compared with other commonly used batteries, lithium-ion batteries are featured by high energy density, high power density, long service life and environmental friendliness and thus have found wide application in the area of consumer electronics. However, lithium-ion batteries for vehicles have high capacity and large serial-parallel numbers, which, coupled with such problems as safety, durability, uniformity and cost, imposes limitations on the wide application of lithium-ion batteries in the vehicle. The narrow area in which lithium-ion batteries operate with safety and reliability necessitates the effective control and management of battery management system. This present paper, through the analysis of literature and in combination with our practical experience, gives a brief introduction to the composition of the battery management system (BMS) and its key issues such as battery cell voltage measurement, battery states estimation, battery uniformity and equalization, battery fault diagnosis and so on, in the hope of providing some inspirations to the design and research of the battery management system.
Pre-compound emission in low-energy heavy-ion interactions
NASA Astrophysics Data System (ADS)
Sharma, Manoj Kumar; Shuaib, Mohd.; Sharma, Vijay R.; Yadav, Abhishek; Singh, Pushpendra P.; Singh, Devendra P.; Unnati; Singh, B. P.; Prasad, R.
2017-11-01
Recent experimental studies have shown the presence of pre-compound emission component in heavy ion reactions at low projectile energy ranging from 4 to 7 MeV/nucleons. In earlier measurements strength of the pre-compound component has been estimated from the difference in forward-backward distributions of emitted particles. Present measurement is a part of an ongoing program on the study of reaction dynamics of heavy ion interactions at low energies aimed at investigating the effect of momentum transfer in compound, precompound, complete and incomplete fusion processes in heavy ion reactions. In the present work on the basis of momentum transfer the measurement of the recoil range distributions of heavy residues has been used to decipher the components of compound and pre-compound emission processes in the fusion of 16O projectile with 159Tb and 169Tm targets. The analysis of recoil range distribution measurements show two distinct linear momentum transfer components corresponding to pre-compound and compound nucleus processes are involved. In order to obtain the mean input angular momentum associated with compound and pre-compound emission processes, an online measurement of the spin distributions of the residues has been performed. The analysis of spin distribution indicate that the mean input angular momentum associated with pre-compound products is found to be relatively lower than that associated with compound nucleus process. The pre-compound components obtained from the present analysis are consistent with those obtained from the analysis of excitation functions.
Theoretical nuclear database for high-energy, heavy-ion (HZE) transport
NASA Technical Reports Server (NTRS)
Townsend, L. W.; Cucinotta, F. A.; Wilson, J. W.
1995-01-01
Theoretical methods for estimating high-energy, heavy-ion (HZE) particle absorption and fragmentation cross-sections are described and compared with available experimental data. Differences between theory and experiment range from several percent for absorption cross-sections up to about 25%-50% for fragmentation cross-sections.
Two-stage synergy of electronic energy loss with defects in LiTaO 3 under ion irradiation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sellami, Neila; Crespillo, Miguel L.; Zhang, Yanwen
Understanding energy dissipation in electronic and atomic subsystems and subsequent defect evolution is a scientific challenge. Separate and combined effects of electronic and nuclear energy deposition in z-cut LiTaO 3 have been investigated. Irradiation of pristine LiTaO 3 samples with 2 MeV Ta ions leads to amorphization due to atomic displacement damage, described by a disorder accumulation model. Here, while 21 MeV Si ions do not produce significant damage in pristine LiTaO 3, introduction of pre-existing defects sensitizes LiTaO 3 to the formation of ion tracks from the electronic energy loss by 21 MeV Si ions that induce a synergisticmore » two-stage phase transition process.« less
Two-stage synergy of electronic energy loss with defects in LiTaO 3 under ion irradiation
Sellami, Neila; Crespillo, Miguel L.; Zhang, Yanwen; ...
2018-03-27
Understanding energy dissipation in electronic and atomic subsystems and subsequent defect evolution is a scientific challenge. Separate and combined effects of electronic and nuclear energy deposition in z-cut LiTaO 3 have been investigated. Irradiation of pristine LiTaO 3 samples with 2 MeV Ta ions leads to amorphization due to atomic displacement damage, described by a disorder accumulation model. Here, while 21 MeV Si ions do not produce significant damage in pristine LiTaO 3, introduction of pre-existing defects sensitizes LiTaO 3 to the formation of ion tracks from the electronic energy loss by 21 MeV Si ions that induce a synergisticmore » two-stage phase transition process.« less
NASA Astrophysics Data System (ADS)
Tsuji, H.; Ebihara, Y.; Tanaka, T.
2017-04-01
An interplanetary (IP) shock has a large impact on magnetospheric ions. Satellite observations have shown that soon after arrival of the IP shock, overall intensity of the ions rapidly increases and multiple energy dispersion appears in an energy-time spectrogram of the ions. In order to understand the response of the magnetospheric ions to IP shock, we have performed test particle simulation under the electric and magnetic fields provided by the global magnetohydrodynamic simulation. We reconstructed the differential flux of H+, He+, and O+ ions at (7, 0, 0) Re in GSM coordinates by means of the semi-Lagrangian (phase space mapping) method. Simulation results show that the ions respond to the IP shock in two different ways. First, overall intensity of the flux gradually increases at all pitch angles. As the compressional wave propagates tailward, the magnetic field increases, which accelerates the ions due to the gyrobetatron. Second, multiple energy-time dispersion appears in the reconstructed spectrograms of the ion flux. The energy-time dispersion is caused by the ion moving toward mirror point together with tailward propagating compressional wave at off-equator. The ions are primarily accelerated by the drift betatron under the strong electric field looking dawnward. The dispersion is absent in the spectrogram of equatorially mirroring ions. The dispersion appears at higher energy for heavier ions. These features are consistent with the satellite observations. Because the acceleration depends on bounce phase, the bounce-averaged approximation is probably invalid for the ions during the interval of geomagnetic sudden commencement.
Narrow beam neutron dosimetry.
Ferenci, M Sutton
2004-01-01
Organ and effective doses have been estimated for male and female anthropomorphic mathematical models exposed to monoenergetic narrow beams of neutrons with energies from 10(-11) to 1000 MeV. Calculations were performed for anterior-posterior, posterior-anterior, left-lateral and right-lateral irradiation geometries. The beam diameter used in the calculations was 7.62 cm and the phantoms were irradiated at a height of 1 m above the ground. This geometry was chosen to simulate an accidental scenario (a worker walking through the beam) at Flight Path 30 Left (FP30L) of the Weapons Neutron Research (WNR) Facility at Los Alamos National Laboratory. The calculations were carried out using the Monte Carlo transport code MCNPX 2.5c.
Linked gas chromatograph-thermal energy analyzer/ion trap mass spectrometer
DOE Office of Scientific and Technical Information (OSTI.GOV)
Alcaraz, A.; Martin, W.H.; Andresen, B.D.
1991-05-01
The capability of comparing a nitrogen chromatogram generated from a gas chromatograph (GC, Varian model 3400) linked to a thermal energy analyzer (TEA, Thermedics Inc. Model 610) with a total ion chromatogram (from a Finnigan-MAT Ion Trap Mass Spectrometer, ITMS) has provided a new means to screen and identifying trace levels of nitrogen-containing compounds in complex mixtures. Prior to the work described here, it has not been possible to simultaneously acquire TEA and MS data. What was needed was a viable GC-TEA/ITMS interface to combine the capabilities of both instruments. 4 figs.
Low-energy plasma immersion ion implantation to induce DNA transfer into bacterial E. coli
NASA Astrophysics Data System (ADS)
Sangwijit, K.; Yu, L. D.; Sarapirom, S.; Pitakrattananukool, S.; Anuntalabhochai, S.
2015-12-01
Plasma immersion ion implantation (PIII) at low energy was for the first time applied as a novel biotechnology to induce DNA transfer into bacterial cells. Argon or nitrogen PIII at low bias voltages of 2.5, 5 and 10 kV and fluences ranging from 1 × 1012 to 1 × 1017 ions/cm2 treated cells of Escherichia coli (E. coli). Subsequently, DNA transfer was operated by mixing the PIII-treated cells with DNA. Successes in PIII-induced DNA transfer were demonstrated by marker gene expressions. The induction of DNA transfer was ion-energy, fluence and DNA-size dependent. The DNA transferred in the cells was confirmed functioning. Mechanisms of the PIII-induced DNA transfer were investigated and discussed in terms of the E. coli cell envelope anatomy. Compared with conventional ion-beam-induced DNA transfer, PIII-induced DNA transfer was simpler with lower cost but higher efficiency.
Simple method for determining binding energies of fullerene and complex atomic negative ions
NASA Astrophysics Data System (ADS)
Felfli, Zineb; Msezane, Alfred
2017-04-01
A robust potential which embeds fully the vital core polarization interaction has been used in the Regge pole method to explore low-energy electron scattering from C60, Eu and Nb through the total cross sections (TCSs) calculations. From the characteristic dramatically sharp resonances in the TCSs manifesting negative ion formation in these systems, we extracted the binding energies for the C60, Euand Nbanions they are found to be in outstanding agreement with the measured electron affinities of C60, Eu and Nb. Common among these considered systems, including the standard atomic Au is the formation of their ground state negative ions at the second Ramsauer-Townsend (R-T) minima of their TCSs. Indeed, this is a signature of all the fullerenes and complex atoms considered thus far. Shape resonances, R-T minima and binding energies of the resultant anions are presented. This work was supported by U.S. DOE, Basic Energy Sciences, Office of Energy Research.
Emittance measurements in low energy ion storage rings
NASA Astrophysics Data System (ADS)
Hunt, J. R.; Carli, C.; Resta-López, J.; Welsch, C. P.
2018-07-01
The development of the next generation of ultra-low energy antiproton and ion facilities requires precise information about the beam emittance to guarantee optimum performance. In the Extra-Low ENergy Antiproton storage ring (ELENA) the transverse emittances will be measured by scraping. However, this diagnostic measurement faces several challenges: non-zero dispersion, non-Gaussian beam distributions due to effects of the electron cooler and various systematic errors such as closed orbit offsets and inaccurate rms momentum spread estimation. In addition, diffusion processes, such as intra-beam scattering might lead to emittance overestimates. Here, we present algorithms to efficiently address the emittance reconstruction in presence of the above effects, and present simulation results for the case of ELENA.
NASA Astrophysics Data System (ADS)
Dogar, A. H.; Ullah, S.; Qayyum, H.; Rehman, Z. U.; Qayyum, A.
2017-09-01
The ion flux from various metals (Al, Ti, Cu, Sn and W) ablated with 20 ns Nd:YAG laser radiation at a wavelength of 1064 nm was investigated by an ion collector operating in time-of-flight (TOF) configuration. The laser irradiance at the target was varied in the range of 1.7 × 108-5.73 × 108 W cm-2. Ion yield from various metals showed a linearly increasing trend with increasing laser irradiance, whereas ion yield was found to decrease with an increasing atomic mass of the target. Our results clearly indicate that ion yield is not a function of the volatility of the metal. TOF ion spectra showed at least two groups of low intensity peaks due to fast ions. The first group of ion peaks, which was present in the spectra of all five metals, was due to surface contamination. The additional fast ion structures in the spectra of Sn and W can be related to the ion acceleration due to the prompt electron emission from these high-Z metals. The ion velocity follows the anticipated inverse square root dependence on the ion mass. For the range of laser irradiance investigated here, the most probable energy of the Cu ions increases from about 100-600 eV. The fast increase in ion energy above ~3 × 108 W cm-2 is related to the increase of the Columb part of the ion energy due to the production of multiply charged ions.
Advanced Electrode Materials for High Energy Next Generation Li ion Batteries
NASA Astrophysics Data System (ADS)
Hayner, Cary Michael
Lithium ion batteries are becoming an increasingly ubiquitous part of modern society. Since their commercial introduction by Sony in 1991, lithium-ion batteries have grown to be the most popular form of electrical energy storage for portable applications. Today, lithium-ion batteries power everything from cellphones and electric vehicles to e-cigarettes, satellites, and electric aircraft. Despite the commercialization of lithium-ion batteries over twenty years ago, it remains the most active field of energy storage research for its potential improvement over current technology. In order to capitalize on these opportunities, new materials with higher energy density and storage capacities must be developed. Unfortunately, most next-generation materials suffer from rapid capacity degradation or severe loss of capacity when rapidly discharged. In this dissertation, the development of novel anode and cathode materials for advanced high-energy and high-power lithium-ion batteries is reported. In particular, the application of graphene-based materials to stabilize active material is emphasized. Graphene, a unique two-dimensional material composed of atomically thin carbon sheets, has shown potential to address unsatisfactory rate capability, limited cycling performance and abrupt failure of these next-generation materials. This dissertation covers four major subjects: development of silicon-graphene composites, impact of carbon vacancies on graphene high-rate performance, iron fluoride-graphene composites, and ternary iron-manganese fluoride synthesis. Silicon is considered the most likely material to replace graphite as the anode active material for lithium-ion batteries due to its ability to alloy with large amounts of lithium, leading to significantly higher specific capacities than the graphite standard. However, Si also expands in size over 300% upon lithiation, leading to particle fracture and isolation from conductive support, resulting in cell failure within a few
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nagatomo, T., E-mail: nagatomo@riken.jp; Kase, M.; Kamigaito, O.
2016-02-15
Several fluorescent materials were tested for use in the imaging screen of a pepper-pot emittance meter that is suitable for investigating the beam dynamics of multiply charged heavy ions extracted from an ECR ion source. SiO{sub 2} (quartz), KBr, Eu-doped CaF{sub 2}, and Tl-doped CsI crystals were first irradiated with 6.52-keV protons to determine the effects of radiation damage on their fluorescence emission properties. For such a low-energy proton beam, only the quartz was found to be a suitable fluorescent material, since the other materials suffered a decay in fluorescence intensity with irradiation time. Subsequently, quartz was irradiated with heavymore » {sup 12}C{sup 4+}, {sup 16}O{sup 4+}, and {sup 40}Ar{sup 11+} ions, but it was found that the fluorescence intensity decreased too rapidly to measure the emittance of these heavy-ion beams. These results suggest that a different energy loss mechanism occurs for heavier ions and for protons.« less
NASA Technical Reports Server (NTRS)
Wilson, John W. (Inventor); Tripathi, Ram K. (Inventor); Cucinotta, Francis A. (Inventor); Badavi, Francis F. (Inventor)
2012-01-01
An apparatus, method and program storage device for determining high-energy neutron/ion transport to a target of interest. Boundaries are defined for calculation of a high-energy neutron/ion transport to a target of interest; the high-energy neutron/ion transport to the target of interest is calculated using numerical procedures selected to reduce local truncation error by including higher order terms and to allow absolute control of propagated error by ensuring truncation error is third order in step size, and using scaling procedures for flux coupling terms modified to improve computed results by adding a scaling factor to terms describing production of j-particles from collisions of k-particles; and the calculated high-energy neutron/ion transport is provided to modeling modules to control an effective radiation dose at the target of interest.
NASA Astrophysics Data System (ADS)
Harper, Conner C.; Elliott, Andrew G.; Lin, Haw-Wei; Williams, Evan R.
2018-06-01
A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (> 300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MSn), as well as the cross sections of ions measured using CDMS.
Harper, Conner C; Elliott, Andrew G; Lin, Haw-Wei; Williams, Evan R
2018-06-02
A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (> 300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MS n ), as well as the cross sections of ions measured using CDMS. Graphical Abstract.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jang, Hyojae, E-mail: lkcom@ibs.re.kr; Jin, Hyunchang; Jang, Ji-Ho
2016-02-15
A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, developmentmore » of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.« less
Yu, Tao; Wang, Xiao-Qing; Sang, Jian-Ping; Pan, Chun-Xu; Zou, Xian-Wu; Chen, Tsung-Yu; Zou, Xiaoqin
2012-01-01
Mutations in ClC channel proteins may cause serious functional changes and even diseases. The function of ClC proteins mainly manifests as Cl− transport, which is related to the binding free energies of chloride ions. Therefore, the influence of a mutation on ClC function can be studied by investigating the mutational effect on the binding free energies of chloride ions. The present study provides quantitative and systematic investigations on the influences of residue mutations on the electrostatic binding free energies in Escherichia coli ClC (EcClC) proteins, using all-atom molecular dynamics simulations. It was found that the change of the electrostatic binding free energy decreases linearly with the increase of the residue-chloride ion distance for a mutation. This work reveals how changes in the charge of a mutated residue and in the distance between the mutated residue and the binding site govern the variations in the electrostatic binding free energies, and therefore influence the transport of chloride ions and conduction in EcClC. This work would facilitate our understanding of the mutational effects on transport of chloride ions and functions of ClC proteins, and provide a guideline to estimate which residue mutations will have great influences on ClC functions. PMID:22612693
The interactions of high-energy, highly-charged ions with fullerenes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ali, R.; Berry, H.G.; Cheng, S.
1996-03-01
In 1985, Robert Curl and Richard Smalley discovered a new form of carbon, the fullerene, C{sub 60}, which consists of 60 carbon atoms in a closed cage resembling a soccer ball. In 1990, Kritschmer et al. were able to make macroscopic quantities of fullerenes. This has generated intense activity to study the properties of fullerenes. One area of research involves collisions between fullerenes and atoms, ions or electrons. In this paper we describe experiments involving interactions between fullerenes and highly charged ions in which the center-of-mass energies exceed those used in other work by several orders of magnitude. The highmore » values of projectile velocity and charge state result in excitation and decay processes differing significantly from those seen in studies 3 at lower energies. Our results are discussed in terms of theoretical models analogous to those used in nuclear physics and this provides an interesting demonstration of the unity of physics.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nogami, Keisuke; Sakai, Yasuhiro; Mineta, Shota
2015-11-15
Visible emission spectra were acquired from neutral atoms sputtered by 35–60 keV Kr{sup +} ions from a polycrystalline tungsten surface. Mean velocities of excited tungsten atoms in seven different 6p states were also obtained via the dependence of photon intensities on the distance from the surface. The average velocities parallel to the surface normal varied by factors of 2–4 for atoms in the different 6p energy levels. However, they were almost independent of the incident ion kinetic energy. The 6p-level energy dependence indicated that the velocities of the excited atoms were determined by inelastic processes that involve resonant charge exchange.
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.
The Tacoma Narrows Bridge Collapse on Film and Video
ERIC Educational Resources Information Center
Olson, Don; Hook, Joseph; Doescher, Russell; Wolf, Steven
2015-01-01
This month marks the 75th anniversary of the Tacoma Narrows Bridge collapse. During a gale on Nov. 7, 1940, the bridge exhibited remarkable oscillations before collapsing spectacularly (Figs. 1-5). Physicists over the years have spent a great deal of time and energy studying this event. By using open-source analysis tools and digitized footage of…
Ion energy distributions in bipolar pulsed-dc discharges of methane measured at the biased cathode
NASA Astrophysics Data System (ADS)
Corbella, C.; Rubio-Roy, M.; Bertran, E.; Portal, S.; Pascual, E.; Polo, M. C.; Andújar, J. L.
2011-02-01
The ion fluxes and ion energy distributions (IED) corresponding to discharges in methane (CH4) were measured in time-averaged mode with a compact retarding field energy analyser (RFEA). The RFEA was placed on a biased electrode at room temperature, which was powered by either radiofrequency (13.56 MHz) or asymmetric bipolar pulsed-dc (250 kHz) signals. The shape of the resulting IED showed the relevant populations of ions bombarding the cathode at discharge parameters typical in the material processing technology: working pressures ranging from 1 to 10 Pa and cathode bias voltages between 100 and 200 V. High-energy peaks in the IED were detected at low pressures, whereas low-energy populations became progressively dominant at higher pressures. This effect is attributed to the transition from collisionless to collisional regimes of the cathode sheath as the pressure increases. On the other hand, pulsed-dc plasmas showed broader IED than RF discharges. This fact is connected to the different working frequencies and the intense peak voltages (up to 450 V) driven by the pulsed power supply. This work improves our understanding in plasma processes at the cathode level, which are of crucial importance for the growth and processing of materials requiring controlled ion bombardment. Examples of industrial applications with these requirements are plasma cleaning, ion etching processes during fabrication of microelectronic devices and plasma-enhanced chemical vapour deposition of hard coatings (diamond-like carbon, carbides and nitrides).
NASA Astrophysics Data System (ADS)
Wang, Yue; Shen, Xiao-Liang; Zheng, Rui-Lin; Guo, Hai-Tao; Lv, Peng; Liu, Chun-Xiao
2018-01-01
Ion implantation has demonstrated to be an efficient and reliable technique for the fabrication of optical waveguides in a diversity of transparent materials. Photo-thermal-refractive glass (PTR) is considered to be durable and stable holographic recording medium. Optical planar waveguide structures in the PTR glasses were formed, for the first time to our knowledge, by the C3+-ion implantation with single-energy (6.0 MeV) and double-energy (5.5+6.0 MeV), respectively. The process of the carbon ion implantation was simulated by the stopping and range of ions in matter code. The morphologies of the waveguides were recorded by a microscope operating in transmission mode. The guided beam distributions of the waveguides were measured by the end-face coupling technique. Comparing with the single-energy implantation, the double-energy implantation improves the light confinement for the dark-mode spectrum. The guiding properties suggest that the carbon-implanted PTR glass waveguides have potential for the manufacture of photonic devices.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yoshimura, Satoru, E-mail: yosimura@ppl.eng.osaka-u.ac.jp; Sugimoto, Satoshi; Kiuchi, Masato
2016-03-14
We have proposed an experimental methodology which makes it possible to deposit silicon carbide (SiC) films on Si substrates with a low-energy mass-selected ion beam system using hexamethyldisilane (HMD) as a gas source. In this study, one of the fragment ions produced from HMD, SiCH{sub 4}{sup +}, was mass-selected. The ion energy was approximately 100 eV. Then, the SiCH{sub 4}{sup +} ions were irradiated to a Si(100) substrate. When the temperature of the Si substrate was set at 800 °C during the ion irradiation, the X-ray diffraction and Raman spectroscopy of the substrate following the completion of ion irradiation experiment demonstrated themore » occurrence of 3C-SiC deposition.« less
Unimolecular reaction energies for polycyclic aromatic hydrocarbon ions.
West, Brandi; Rodriguez Castillo, Sarah; Sit, Alicia; Mohamad, Sabria; Lowe, Bethany; Joblin, Christine; Bodi, Andras; Mayer, Paul M
2018-03-07
Imaging photoelectron photoion coincidence spectroscopy was employed to explore the unimolecular dissociation of the ionized polycyclic aromatic hydrocarbons (PAHs) acenaphthylene, fluorene, cyclopenta[d,e,f]phenanthrene, pyrene, perylene, fluoranthene, dibenzo[a,e]pyrene, dibenzo[a,l]pyrene, coronene and corannulene. The primary reaction is always hydrogen atom loss, with the smaller species also exhibiting loss of C 2 H 2 to varying extents. Combined with previous work on smaller PAH ions, trends in the reaction energies (E 0 ) for loss of H from sp 2 -C and sp 3 -C centres, along with hydrocarbon molecule loss were found as a function of the number of carbon atoms in the ionized PAHs ranging in size from naphthalene to coronene. In the case of molecules which possessed at least one sp 3 -C centre, the activation energy for the loss of an H atom from this site was 2.34 eV, with the exception of cyclopenta[d,e,f]phenanthrene (CPP) ions, for which the E 0 was 3.44 ± 0.86 eV due to steric constraints. The hydrogen loss from PAH cations and from their H-loss fragments exhibits two trends, depending on the number of unpaired electrons. For the loss of the first hydrogen atom, the energy is consistently ca. 4.40 eV, while the threshold to lose the second hydrogen atom is much lower at ca. 3.16 eV. The only exception was for the dibenzo[a,l]pyrene cation, which has a unique structure due to steric constraints, resulting in a low H loss reaction energy of 2.85 eV. If C 2 H 2 is lost directly from the precursor cation, the energy required for this dissociation is 4.16 eV. No other fragmentation channels were observed over a large enough sample set for trends to be extrapolated, though data on CH 3 and C 4 H 2 loss obtained in previous studies is included for completeness. The dissociation reactions were also studied by collision induced dissociation after ionization by atmospheric pressure chemical ionization. When modeled with a simple temperature-based theory for the
Photon and dilepton production in high energy heavy ion collisions
Sakaguchi, Takao
2015-05-07
The recent results on direct photons and dileptons in high energy heavy ion collisions, obtained particularly at RHIC and LHC are reviewed. The results are new not only in terms of the probes, but also in terms of the precision. We shall discuss the physics learned from the results.
Droplet squeezing through a narrow constriction: Minimum impulse and critical velocity
NASA Astrophysics Data System (ADS)
Zhang, Zhifeng; Drapaca, Corina; Chen, Xiaolin; Xu, Jie
2017-07-01
Models of a droplet passing through narrow constrictions have wide applications in science and engineering. In this paper, we report our findings on the minimum impulse (momentum change) of pushing a droplet through a narrow circular constriction. The existence of this minimum impulse is mathematically derived and numerically verified. The minimum impulse happens at a critical velocity when the time-averaged Young-Laplace pressure balances the total minor pressure loss in the constriction. Finally, numerical simulations are conducted to verify these concepts. These results could be relevant to problems of energy optimization and studies of chemical and biomedical systems.
Ion Binding Energies Determining Functional Transport of ClC Proteins
NASA Astrophysics Data System (ADS)
Yu, Tao; Guo, Xu; Zou, Xian-Wu; Sang, Jian-Ping
2014-06-01
The ClC-type proteins, a large family of chloride transport proteins ubiquitously expressed in biological organisms, have been extensively studied for decades. Biological function of ClC proteins can be reflected by analyzing the binding situation of Cl- ions. We investigate ion binding properties of ClC-ec1 protein with the atomic molecular dynamics simulation approach. The calculated electrostatic binding energy results indicate that Cl- at the central binding site Scen has more binding stability than the internal binding site Sint. Quantitative comparison between the latest experimental heat release data isothermal titration calorimetry (ITC) and our calculated results demonstrates that chloride ions prefer to bind at Scen than Sint in the wild-type ClC-ec1 structure and prefer to bind at Sext and Scen than Sint in mutant E148A/E148Q structures. Even though the chloride ions make less contribution to heat release when binding to Sint and are relatively unstable in the Cl- pathway, they are still part contributors for the Cl- functional transport. This work provides a guide rule to estimate the importance of Cl- at the binding sites and how chloride ions have influences on the function of ClC proteins.
Steady-state turbulence with a narrow inertial range
NASA Technical Reports Server (NTRS)
Weatherall, J. C.; Nicholson, D. R.; Goldman, M. V.
1983-01-01
Coupled two-dimensional wave equations are solved on a computer to model Langmuir wave turbulence excited by a weak electron beam. The model includes wave growth due to beam-plasma interaction, and dissipation by Landau damping. The inertial range is limited to a relatively small number of modes such as could occur when the ratio of masses between the negative and positive ions is larger than in a hydrogen plasma, or when there is damping in long wavelength Langmuir waves. A steady state is found consisting of quasistable, collapsed wave packets. The effects of different beam parameters and the assumed narrow inertial range are considered. The results may be relevant to plasma turbulence observed in connection with type III solar bursts.
The Effect of Ion Energy and Substrate Temperature on Deuterium Trapping in Tungsten
NASA Astrophysics Data System (ADS)
Roszell, John Patrick Town
Tungsten is a candidate plasma facing material for next generation magnetic fusion devices such as ITER and there are major operational and safety issues associated with hydrogen (tritium) retention in plasma facing components. An ion gun was used to simulate plasma-material interactions under various conditions in order to study hydrogen retention characteristics of tungsten thus enabling better predictions of hydrogen retention in ITER. Thermal Desorption Spectroscopy (TDS) was used to measure deuterium retention from ion irradiation while modelling of TDS spectra with the Tritium Migration Analysis Program (TMAP) was used to provide information about the trapping mechanisms involved in deuterium retention in tungsten. X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) were used to determine the depth resolved composition of specimens used for irradiation experiments. Carbon and oxygen atoms will be among the most common contaminants within ITER. C and O contamination in polycrystalline tungsten (PCW) specimens even at low levels (˜0.1%) was shown to reduce deuterium retention by preventing diffusion of deuterium into the bulk of the specimen. This diffusion barrier was also responsible for the inhibition of blister formation during irradiations at 500 K. These observations may provide possible mitigation techniques for problems associated with tritium retention and mechanical damage to plasma facing components caused by hydrogen implantation. Deuterium trapping in PCW and single crystal tungsten (SCW) was studied as a function of ion energy and substrate temperature. Deuterium retention was shown to decrease with decreasing ion energy below 100 eV/D+. Irradiation of tungsten specimens with 10 eV/D+ ions was shown to retain up to an order of magnitude less deuterium than irradiation with 500 eV/D+ ions. Furthermore, the retention mechanism for deuterium was shown to be consistent across the entire energy range studied (10-500 e
NASA Astrophysics Data System (ADS)
Alexander, Frauke; Villagrasa, Carmen; Rabus, Hans; Wilkens, Jan J.
2015-09-01
The BioQuaRT project within the European Metrology Research Programme aims at correlating ion track structure characteristics with the biological effects of radiation and develops measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigate methods to translate track-structure quantities derived on a nanometre scale to macroscopic dimensions. Input data sets were generated by simulations of ion tracks of protons and carbon ions in liquid water using the Geant 4 Monte Carlo toolkit with the Geant4-DNA processes. Based on the energy transfer points - recorded with nanometre resolution - we investigated parametrisations of overall properties of ion track structure. Three different track structure parametrisations have been developed using the distances to the 10 next neighbouring ionisations, the radial energy distribution and ionisation cluster size distributions. These parametrisations of nanometric track structure build a basis for deriving biologically relevant mean values which are essential in the clinical situation where each voxel is exposed to a mixed radiation field. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.
Liu, Feng; Wang, Yugang; Xue, Jianming; Wang, Sixue; Du, Guanhua; Zhao, Weijiang
2003-02-01
The penetration depth of low-energy heavy ions in botanic samples was detected with a new transmission measurement. In the measurement, highly oriented pyrolytic graphite (HOPG) pieces were placed behind the botanic samples with certain thickness. During the irradiation of heavy ions with energy of tens of keV, the energetic particles transmitted from those samples were received by the HOPG pieces. After irradiation, scanning tunneling microscope (STM) was applied to observe protrusion-like damage induced by these transmitted ions on the surface of the HOPG. The statistical average number density of protrusions and the minimum transmission rate of the low-energy heavy ions can be obtained. The detection efficiency of the new method for low-energy heavy ions was about 0.1-1 and the background in the measurement can be reduced to as low as 1.0 x 10(8) protrusions/cm2. With this method, the penetration depth of the energetic particles was detected to be no less than 60 micrometers in kidney bean slices when the slices were irradiated by 100 keVAr+ ion at the fluence of 5 x 10(16) ions/cm2. c2002 Elsevier Science Ltd. All rights reserved.
NASA Technical Reports Server (NTRS)
Liu, Feng; Wang, Yugang; Xue, Jianming; Wang, Sixue; Du, Guanhua; Zhao, Weijiang
2003-01-01
The penetration depth of low-energy heavy ions in botanic samples was detected with a new transmission measurement. In the measurement, highly oriented pyrolytic graphite (HOPG) pieces were placed behind the botanic samples with certain thickness. During the irradiation of heavy ions with energy of tens of keV, the energetic particles transmitted from those samples were received by the HOPG pieces. After irradiation, scanning tunneling microscope (STM) was applied to observe protrusion-like damage induced by these transmitted ions on the surface of the HOPG. The statistical average number density of protrusions and the minimum transmission rate of the low-energy heavy ions can be obtained. The detection efficiency of the new method for low-energy heavy ions was about 0.1-1 and the background in the measurement can be reduced to as low as 1.0 x 10(8) protrusions/cm2. With this method, the penetration depth of the energetic particles was detected to be no less than 60 micrometers in kidney bean slices when the slices were irradiated by 100 keVAr+ ion at the fluence of 5 x 10(16) ions/cm2. c2002 Elsevier Science Ltd. All rights reserved.
Ion implantation in nanodiamonds: size effect and energy dependence.
Shiryaev, Andrey A; Hinks, Jonathan A; Marks, Nigel A; Greaves, Graeme; Valencia, Felipe J; Donnelly, Stephen E; González, Rafael I; Kiwi, Miguel; Trigub, Alexander L; Bringa, Eduardo M; Fogg, Jason L; Vlasov, Igor I
2018-03-23
Nanoparticles are ubiquitous in nature and are increasingly important for technology. They are subject to bombardment by ionizing radiation in a diverse range of environments. In particular, nanodiamonds represent a variety of nanoparticles of significant fundamental and applied interest. Here we present a combined experimental and computational study of the behaviour of nanodiamonds under irradiation by xenon ions. Unexpectedly, we observed a pronounced size effect on the radiation resistance of the nanodiamonds: particles larger than 8 nm behave similarly to macroscopic diamond (i.e. characterized by high radiation resistance) whereas smaller particles can be completely destroyed by a single impact from an ion in a defined energy range. This latter observation is explained by extreme heating of the nanodiamonds by the penetrating ion. The obtained results are not limited to nanodiamonds, making them of interest for several fields, putting constraints on processes for the controlled modification of nanodiamonds, on the survival of dust in astrophysical environments, and on the behaviour of actinides released from nuclear waste into the environment.
The charge-energy-mass spectrometer for 0.3-300 keV/e ions on the AMPTE CCE
NASA Technical Reports Server (NTRS)
Gloeckler, G.; Ipavich, F. M.; Hamilton, D. C.; Lundgren, R. A.; Studemann, W.; Wilken, B.; Kremser, G.; Hovestadt, D.; Gliem, F.; Rieck, W.
1985-01-01
The charge-energy-mass (CHEM) spectrometer on the Charge Composition Explorer (CCE) has the function to measure the energy spectra, pitch-angle distributions, and ionization states of ions in the earth's magnetosphere and magnetosheath in the energy range from 0.3 to 300 keV/charge with a time resolution of less than 1 min. The obtained data will provide essential information on outstanding problems related to ion sources and dynamical processes of space plasmas and of suprathermal ions. A description of the CHEM experiment is given, taking into account the principle of operation, the sensor, the electronics, instrument characteristics, specifications, and requirements. Questions of postlaunch performance are also discussed.
NASA Astrophysics Data System (ADS)
Moribayashi, Kengo
2018-05-01
Using simulations, we have evaluated the effect of the track potential on the motion and energy flow of secondary electrons, with the goal of determining the spatial distribution of energy deposition due to irradiation with heavy ions. We have simulated this effect as a function of the mean path τ between the incident ion-impact-ionization events at ion energies Eion. Here, the track potential is the potential formed from electric field near this incident ion path. The simulations indicate that this effect is mainly determined by τ and hardly depends on Eion. To understand heavy ion beam science more deeply and to reduce the time required by simulations, we have proposed simple approximation methods that almost reproduce the simulation results here.
Plasma ion-induced molecular ejection on the Galilean satellites - Energies of ejected molecules
NASA Technical Reports Server (NTRS)
Johnson, R. E.; Boring, J. W.; Reimann, C. T.; Barton, L. A.; Sieveka, E. M.; Garrett, J. W.; Farmer, K. R.; Brown, W. L.; Lanzerotti, L. J.
1983-01-01
First measurements of the energy of ejection of molecules from icy surfaces by fast incident ions are presented. Such results are needed in discussions of the Jovian and Saturnian plasma interactions with the icy satellites. In this letter parameters describing the ion-induced ejection and redistribution of molecules on the Galilean satellites are recalculated in light of the new laboratory data.
Sreenath, Kesavapillai; Yuan, Zhao; Allen, John R.
2015-01-01
We demonstrate a strategy to transfer the zinc(II) sensitivity of a fluoroionophore with low photostability and a broad emission band to a bright and photostable fluorophore with a narrow emission band. The two fluorophores are covalently connected to afford an intramolecular Förster resonance energy transfer (FRET) conjugate. The FRET donor in the conjugate is a zinc(II)-sensitive arylvinylbipyridyl fluoroionophore, the absorption and emission of which undergo bathochromic shifts upon zinc(II) coordination. When the FRET donor is excited, efficient intramolecular energy transfer occurs to result in the emission of the acceptor boron dipyrromethene (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene or BODIPY) as a function of zinc(II) concentration. The broad emission band of the donor/zinc(II) complex is transformed into the strong, narrow emission band of the BODIPY acceptor in the FRET conjugates, which can be captured within the narrow emission window that is preferred for multicolor imaging experiments. In addition to competing with other nonradiative decay processes of the FRET donor, the rapid intramolecular FRET of the excited FRET-conjugate molecule protects the donor fluorophore from photobleaching, thus enhancing the photostability of the indicator. FRET conjugates 3 and 4 contain aliphatic amino groups, which selectively target lysosomes in mammalian cells. This subcellular localization preference was verified by using confocal fluorescence microscopy, which also shows the zinc(II)-enhanced emission of 3 and 4 in lysosomes. It was further shown using two-color structured illumination microscopy (SIM), which is capable of extending the lateral resolution over the Abbe diffraction limit by a factor of two, that the morpholino-functionalized compound 4 localizes in the interior of lysosomes, rather than anchoring on the lysosomal membranes, of live HeLa cells. PMID:25382395
Effects of low and high energy ion bombardment on ETFE polymer
NASA Astrophysics Data System (ADS)
Minamisawa, R. A.; De Almeida, A.; Abidzina, V.; Parada, M. A.; Muntele, I.; Ila, D.
2007-04-01
The polymer ethylenetetrafluoroethylene (ETFE) is used as anti-adherent coatings for food packages and radiation dosimeters. In this work, we compare the damage induced in ETFE bombarded with 100 keV Si ions with that induced by 1 MeV proton bombardment. The damage depends on the type, energy and intensity of the irradiation. Irradiated films were analyzed with optical absorption photospectrometry, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy to determine the chemical nature of the structural changes caused by ion irradiation. Computer simulations were performed to evaluate the radiation damage.
A pepper-pot emittance meter for low-energy heavy-ion beams
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kremers, H. R.; Beijers, J. P. M.; Brandenburg, S.
2013-02-15
A novel emittance meter has been developed to measure the four-dimensional, transverse phase-space distribution of a low-energy ion beam using the pepper-pot technique. A characteristic feature of this instrument is that the pepper-pot plate, which has a linear array of holes in the vertical direction, is scanned horizontally through the ion beam. This has the advantage that the emittance can also be measured at locations along the beam line where the beam has a large horizontal divergence. A set of multi-channel plates, scintillation screen, and ccd camera is used as a position-sensitive ion detector allowing a large range of beammore » intensities that can be handled. This paper describes the design, construction, and operation of the instrument as well as the data analysis used to reconstruct the four-dimensional phase-space distribution of an ion beam. Measurements on a 15 keV He{sup +} beam are used as an example.« less
Silicon-Based Lithium-Ion Capacitor for High Energy and High Power Application
NASA Technical Reports Server (NTRS)
Wu, James J.; Demattia, Brianne; Loyselle, Patricia; Reid, Concha; Kohout, Lisa
2017-01-01
Si-based Li-ion capacitor has been developed and demonstrated. The results show it is feasible to improve both power density and energy density in this configuration. The applied current density impacts the power and energy density: low current favors energy density while high current favors power density. Active carbon has a better rate capability than Si. Next StepsFuture Directions. Si electrode needs to be further studied and improved. Further optimization of SiAC ratio and evaluation of its impact on energy density and power density.
NASA Astrophysics Data System (ADS)
Basu, Sumit; Nayak, Tapan K.; Datta, Kaustuv
2016-06-01
Heavy-ion collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN probe matter at extreme conditions of temperature and energy density. Most of the global properties of the collisions can be extracted from the measurements of charged-particle multiplicity and pseudorapidity (η ) distributions. We have shown that the available experimental data on beam energy and centrality dependence of η distributions in heavy-ion (Au +Au or Pb +Pb ) collisions from √{sNN}=7.7 GeV to 2.76 TeV are reasonably well described by the AMPT model, which is used for further exploration. The nature of the η distributions has been described by a double Gaussian function using a set of fit parameters, which exhibit a regular pattern as a function of beam energy. By extrapolating the parameters to a higher energy of √{sNN}=5.02 TeV, we have obtained the charged-particle multiplicity densities, η distributions, and energy densities for various centralities. Incidentally, these results match well with some of the recently published data by the ALICE Collaboration.
NASA Astrophysics Data System (ADS)
Kitajima, Kensei; Majima, Takuya; Nishio, Tatsuya; Oonishi, Yoshiki; Mizutani, Shiori; Kohno, Jun-ya; Saito, Manabu; Tsuchida, Hidetsugu
2018-06-01
We have investigated the negative and positive secondary ions emitted from ethanol droplets by 4.0-MeV C3+ impact to reveal the characteristic features of the reaction processes induced by fast heavy ions at the liquid ethanol surface. Analysis of the secondary ions was performed by time-of-flight mass spectrometry for microdroplet targets in a high vacuum environment. Fragment ions, deprotonated cluster ions, and trace amounts of the reaction product ions are observed in the negative secondary ions. The main fragment anions are C2HmO- (m = 1, 3, and 5) and C2H- generated by loss of hydrogen and oxygen atoms. The reaction product anions include deprotonated glycols, larger alcohols, and their dehydrated and dehydrogenated forms generated by secondary reactions between fragments and radicals. Furthermore, C3Hm- (m = 0-2) and C4Hm- (m = 0 and 1) are observed, which could be produced through a plasma state generated in the heavy ion track. Deprotonated ethanol cluster ions, [(EtOH)n - H]-, are observed up to about n = 25. [(EtOH)n - H]- have smaller kinetic energies than the protonated cluster ions (EtOH)nH+. This probably represents the effect of the positive Coulomb potential transiently formed in the ion track. We also discuss the size distributions and structures of the water- and CH2OH-radical-attached ethanol cluster ions.
Foldable, High Energy Density Lithium Ion Batteries
NASA Astrophysics Data System (ADS)
Suresh, Shravan
Lithium Ion Batteries (LIBs) have become ubiquitous owing to its low cost, high energy density and, power density. Due to these advantages, LIBs have garnered a lot of attention as the primary energy storage devices in consumer electronics and electric vehicles. Recent advances in the consumer electronics research and, the drive to reduce greenhouse gases have created a demand for a shape conformable, high energy density batteries. This thesis focuses on the aforementioned two aspects of LIBs: (a) shape conformability (b) energy density and provides potential solutions to enhance them. This thesis is divided into two parts viz. (i) achieving foldability in batteries and, (ii) improving its energy density. Conventional LIBs are not shape conformable due to two limitations viz. inelasticity of metallic foils, and delamination of the active materials while bending. In the first part of the thesis (in Chapter 3), this problem is solved by replacing metallic current collector with Carbon Nanotube Macrofilms (CNMs). CNMs are superelastic films comprising of porous interconnected nanotube network. Using Molecular Dynamics (MD) simulation, we found that in the presence of an interconnected nanotube network CNMs can be fully folded. This is because the resultant stress due to bending and, the effective bending angle at the interface is reduced due to the network of nanotubes. Hence, unlike an isolated nanotube (which ruptures beyond 120 degrees of bending), a network of nanotubes can be completely folded. Thus, by replacing metallic current collector foils with CNMs, the flexibility limitation of a conventional LIB can be transcended. The second part of this thesis focusses on enhancing the energy density of LIBs. Two strategies adopted to achieve this goal are (a) removing the dead weight of the batteries, and (b) incorporating high energy density electrode materials. By incorporating CNMs, the weight of the batteries was reduced by 5-10 times due to low mass loading of
Calculation of the Frequency Distribution of the Energy Deposition in DNA Volumes by Heavy Ions
NASA Technical Reports Server (NTRS)
Plante, Ianik; Cicinotta, Francis A.
2012-01-01
Radiation quality effects are largely determined by energy deposition in small volumes of characteristic sizes less than 10 nm representative of short-segments of DNA, the DNA nucleosome, or molecules initiating oxidative stress in the nucleus, mitochondria, or extra-cellular matrix. On this scale, qualitatively distinct types of molecular damage are possible for high linear energy transfer (LET) radiation such as heavy ions compared to low LET radiation. Unique types of DNA lesions or oxidative damages are the likely outcome of the energy deposition. The frequency distribution for energy imparted to 1-20 nm targets per unit dose or particle fluence is a useful descriptor and can be evaluated as a function of impact parameter from an ions track. In this work, the simulation of 1-Gy irradiation of a cubic volume of 5 micron by: 1) 450 (1)H(+) ions, 300 MeV; 2) 10 (12)C(6+) ions, 290 MeV/amu and 3) (56)Fe(26+) ions, 1000 MeV/amu was done with the Monte-Carlo simulation code RITRACKS. Cylindrical targets are generated in the irradiated volume, with random orientation. The frequency distribution curves of the energy deposited in the targets is obtained. For small targets (i.e. <25 nm size), the probability of an ion to hit a target is very small; therefore a large number of tracks and targets as well as a large number of histories are necessary to obtain statistically significant results. This simulation is very time-consuming and is difficult to perform by using the original version of RITRACKS. Consequently, the code RITRACKS was adapted to use multiple CPU on a workstation or on a computer cluster. To validate the simulation results, similar calculations were performed using targets with fixed position and orientation, for which experimental data are available [5]. Since the probability of single- and double-strand breaks in DNA as function of energy deposited is well know, the results that were obtained can be used to estimate the yield of DSB, and can be extended
Sheath effects on current collection by particle detectors with narrow acceptance angles
NASA Technical Reports Server (NTRS)
Singh, N.; Baugher, C. R.
1981-01-01
Restriction of the aperture acceptance angle of an ion or electron trap on an attracting spacecraft significantly alters the volt-ampere characteristics of the instrument in a low Mach number plasma. It is shown when the angular acceptance of the aperture is restricted the current to the collector tends to be independent of the Debye length. Expressions for the RPA characteristics for both a thin sheath and a thick sheath are derived; and it is shown that as the aperture is narrowed the curves tend toward equivalence.
NASA Astrophysics Data System (ADS)
Pei, Youbin; Xiang, Nong; Shen, Wei; Hu, Youjun; Todo, Y.; Zhou, Deng; Huang, Juan
2018-05-01
Kinetic-MagnetoHydroDynamic (MHD) hybrid simulations are carried out to study fast ion driven toroidal Alfvén eigenmodes (TAEs) on the Experimental Advanced Superconducting Tokamak (EAST). The first part of this article presents the linear benchmark between two kinetic-MHD codes, namely MEGA and M3D-K, based on a realistic EAST equilibrium. Parameter scans show that the frequency and the growth rate of the TAE given by the two codes agree with each other. The second part of this article discusses the resonance interaction between the TAE and fast ions simulated by the MEGA code. The results show that the TAE exchanges energy with the co-current passing particles with the parallel velocity |v∥ | ≈VA 0/3 or |v∥ | ≈VA 0/5 , where VA 0 is the Alfvén speed on the magnetic axis. The TAE destabilized by the counter-current passing ions is also analyzed and found to have a much smaller growth rate than the co-current ions driven TAE. One of the reasons for this is found to be that the overlapping region of the TAE spatial location and the counter-current ion orbits is narrow, and thus the wave-particle energy exchange is not efficient.
Mangalam, Vivek; Pita, Kantisara
2017-08-10
In this work, we study the energy transfer mechanism from ZnO nanocrystals (ZnO-nc) to Eu 3+ ions by fabricating thin-film samples of ZnO-nc and Eu 3+ ions embedded in a SiO₂ matrix using the low-cost sol-gel technique. The time-resolved photoluminescence (TRPL) measurements from the samples were analyzed to understand the contribution of energy transfer from the various ZnO-nc emission centers to Eu 3+ ions. The decay time obtained from the TRPL measurements was used to calculate the energy transfer efficiencies from the ZnO-nc emission centers, and these results were compared with the energy transfer efficiencies calculated from steady-state photoluminescence emission results. The results in this work show that high transfer efficiencies from the excitonic and Zn defect emission centers is mostly due to the energy transfer from ZnO-nc to Eu 3+ ions which results in the radiative emission from the Eu 3+ ions at 614 nm, while the energy transfer from the oxygen defect emissions is most probably due to the energy transfer from ZnO-nc to the new defects created due to the incorporation of the Eu 3+ ions.
Surface modifications of AISI 420 stainless steel by low energy Yttrium ions
NASA Astrophysics Data System (ADS)
Nassisi, Vincenzo; Delle Side, Domenico; Turco, Vito; Martina, Luigi
2018-01-01
In this work, we study surface modifications of AISI 420 stainless steel specimens in order to improve their surface properties. Oxidation resistance and surface micro-hardness were analyzed. Using an ion beam delivered by a Laser Ion Source (LIS) coupled to an electrostatic accelerator, we performed implantation of low energy yttrium ions on the samples. The ions experienced an acceleration passing through a gap whose ends had a potential difference of 60 kV. The gap was placed immediately before the samples surface. The LIS produced high ions fluxes per laser pulse, up to 3x1011 ions/cm2, resulting in a total implanted flux of 7x1015 ions/cm2. The samples were characterized before and after ion implantation using two analytical techniques. They were also thermally treated to investigate the oxide scale. The crystal phases were identified by an X-ray diffractometer, while the micro-hardness was assayed using the scratch test and a profilometer. The first analysis was applied to blank, implanted and thermally treated sample surface, while the latter was applied only to blank and implanted sample surfaces. We found a slight increase in the hardness values and an increase to oxygen resistance. The implantation technique we used has the advantages, with respect to conventional methods, to modify the samples at low temperature avoiding stray diffusion of ions inside the substrate bulk.
Influence of dense plasma on the energy levels and transition properties in highly charged ions
NASA Astrophysics Data System (ADS)
Chen, Zhan-Bin; Hu, Hong-Wei; Ma, Kun; Liu, Xiao-Bin; Guo, Xue-Ling; Li, Shuang; Zhu, Bo-Hong; Huang, Lian; Wang, Kai
2018-03-01
The studies of the influence of plasma environments on the level structures and transition properties for highly charged ions are presented. For the relativistic treatment, we implemented the multiconfiguration Dirac-Fock method incorporating the ion sphere (IS) model potential, in which the plasma screening is taken into account as a modified interaction potential between the electron and the nucleus. For the nonrelativistic treatment, analytical solutions of the Schrödinger equation with two types of the IS screened potential are proposed. The Ritz variation method is used with hydrogenic wave function as a trial wave function that contains two unknown variational parameters. Bound energies are derived from an energy equation, and the variational parameters are obtained from the minimisation condition of the expectation value of the energy. Numerical results for hydrogen-like ions in dense plasmas are presented as examples. A detailed analysis of the influence of relativistic effects on the energy levels and transition properties is also reported. Our results are compared with available results in the literature showing a good quantitative agreement.
Life Prediction Model for Grid-Connected Li-ion Battery Energy Storage System: Preprint
DOE Office of Scientific and Technical Information (OSTI.GOV)
Smith, Kandler A; Saxon, Aron R; Keyser, Matthew A
Life Prediction Model for Grid-Connected Li-ion Battery Energy Storage System: Preprint Lithium-ion (Li-ion) batteries are being deployed on the electrical grid for a variety of purposes, such as to smooth fluctuations in solar renewable power generation. The lifetime of these batteries will vary depending on their thermal environment and how they are charged and discharged. To optimal utilization of a battery over its lifetime requires characterization of its performance degradation under different storage and cycling conditions. Aging tests were conducted on commercial graphite/nickel-manganese-cobalt (NMC) Li-ion cells. A general lifetime prognostic model framework is applied to model changes in capacity andmore » resistance as the battery degrades. Across 9 aging test conditions from 0oC to 55oC, the model predicts capacity fade with 1.4 percent RMS error and resistance growth with 15 percent RMS error. The model, recast in state variable form with 8 states representing separate fade mechanisms, is used to extrapolate lifetime for example applications of the energy storage system integrated with renewable photovoltaic (PV) power generation.« less
A new compact structure for a high intensity low-energy heavy-ion accelerator
NASA Astrophysics Data System (ADS)
Wang, Zhi-Jun; He, Yuan; A. Kolomiets, A.; Liu, Shu-Hui; Du, Xiao-Nan; Jia, Huan; Li, Chao; Wang, Wang-Sheng; Chen, Xi-Meng
2013-12-01
A new compact accelerating structure named Hybrid RFQ is proposed to accelerate a high-intensity low-energy heavy ion beam in HISCL (High Intensive heavy ion SuperConducting Linear accelerator), which is an injector of HIAF (Heavy Ion Advanced Research Facility). It is combined by an alternative series of acceleration gaps and RFQ sections. The proposed structure has a high accelerating ability compared with a conventional RFQ and is more compact than traditional DTLs. A Hybrid RFQ is designed to accelerate 238U34+ from 0.38 MeV/u to 1.33 MeV/u. The operation frequency is described to be 81.25 MHz at CW (continuous wave) mode. The design beam current is 1.0 mA. The results of beam dynamics and RF simulation of the Hybrid RFQ show that the structure has a good performance at the energy range for ion acceleration. The emittance growth is less than 5% in both directions and the RF power is less than 150 kW. In this paper, the results of beam dynamics and RF simulation of the Hybrid RFQ are presented.
NASA Astrophysics Data System (ADS)
Kraft-Bermuth, S.; Andrianov, V.; Bleile, A.; Echler, A.; Egelhof, P.; Grabitz, P.; Kilbourne, C.; Kiselev, O.; McCammon, D.; Scholz, P.
2014-09-01
The precise determination of the transition energy of the Lyman-1 line in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. We report the determination of the Lyman-1 transition energy of gold ions (Au) with microcalorimeters at the experimental storage ring at GSI. X-rays produced by the interaction of 125 MeV/u Au ions with an internal argon gas-jet target were detected. The detector array consisted of 14 pixels with silicon thermistors and Sn absorbers, for which an energy resolution of 50 eV for an X-ray energy of 59.5 keV was obtained in the laboratory. The Lyman-1 transition energy was determined for each pixel in the laboratory frame, then transformed into the emitter frame and averaged. A Dy-159 source was used for energy calibration. The absolute positions of the detector pixels, which are needed for an accurate correction of the Doppler shift, were determined by topographic measurements and by scanning a collimated Am-241 source across the cryostat window. The energy of the Lyman-1 line in the emitter frame is eV, in good agreement with theoretical predictions. The systematic error is dominated by the uncertainty in the position of the cryostat relative to the interaction region of beam and target.
First β-ν correlation measurement from the recoil-energy spectrum of Penning trapped Ar35 ions
NASA Astrophysics Data System (ADS)
Van Gorp, S.; Breitenfeldt, M.; Tandecki, M.; Beck, M.; Finlay, P.; Friedag, P.; Glück, F.; Herlert, A.; Kozlov, V.; Porobic, T.; Soti, G.; Traykov, E.; Wauters, F.; Weinheimer, Ch.; Zákoucký, D.; Severijns, N.
2014-08-01
We demonstrate a novel method to search for physics beyond the standard model by determining the β-ν angular correlation from the recoil-ion energy distribution after β decay of ions stored in a Penning trap. This recoil-ion energy distribution is measured with a retardation spectrometer. The unique combination of the spectrometer with a Penning trap provides a number of advantages, e.g., a high recoil-ion count rate and low sensitivity to the initial position and velocity distribution of the ions and completely different sources of systematic errors compared to other state-of-the-art experiments. Results of a first measurement with the isotope Ar35 are presented. Although currently at limited precision, we show that a statistical precision of about 0.5% is achievable with this unique method, thereby opening up the possibility of contributing to state-of-the-art searches for exotic currents in weak interactions.
On the defect structure due to low energy ion bombardment of graphite
NASA Astrophysics Data System (ADS)
Marton, D.; Bu, H.; Boyd, K. J.; Todorov, S. S.; Al-Bayati, A. H.; Rabalais, J. W.
1995-03-01
Graphite surfaces cleaved perpendicular to the c axis have been irradiated with low doses of Ar + ions at 50 eV kinetic energy and perpendicular incidence. Scanning tunneling micrographs (STM) of these irradiated surfaces exhibited dome-like features as well as point defects. These dome-like features retain undisturbed graphite periodicity. This finding is attributed to the stopping of ions between the first and second graphite sheets. The possibility of doping semiconductors at extremely shallow depths is raised.
NASA Astrophysics Data System (ADS)
Ye, Hui; Ma, Jingming; Feng, Chun; Cheng, Ying; Zhu, Suwen; Cheng, Beijiu
2009-02-01
In the process of the fermentation of steroid C11α-hydroxylgenation strain Aspergillus flavus AF-ANo208, a red pigment is derived, which will affect the isolation and purification of the target product. Low energy ion beam implantation is a new tool for breeding excellent mutant strains. In this study, the ion beam implantation experiments were performed by infusing two different ions: argon ion (Ar+) and nitrogen ion (N+). The results showed that the optimal ion implantation was N+ with an optimum dose of 2.08 × 1015 ions/cm2, with which the mutant strain AF-ANm16 that produced no red pigment was obtained. The strain had high genetic stability and kept the strong capacity of C11α-hydroxylgenation, which could be utilized in industrial fermentation. The differences between the original strain and the mutant strain at a molecular level were analyzed by randomly amplified polymorphic DNA (RAPD). The results indicated that the frequency of variation was 7.00%, which would establish the basis of application investigation into the breeding of pigment mutant strains by low energy ion implantation.
Narrow band gap amorphous silicon semiconductors
Madan, A.; Mahan, A.H.
1985-01-10
Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.
Radiation damage studies of soft magnetic metallic glasses irradiated with high-energy heavy ions
NASA Astrophysics Data System (ADS)
Pavlovič, Márius; Miglierini, Marcel; Mustafin, Edil; Ensinger, Wolfgang; Šagátová, Andrea; Šoka, Martin
2015-01-01
Some soft magnetic metallic glasses are considered for use in magnetic cores of accelerator radio frequency cavities. Due to losses of the circulating ion beam, they may be exposed to irradiation by different ions at different energies. This paper presents data and review results of irradiation experiments concerning the influence of high-energy heavy ions on magnetic susceptibility of VITROPERM®-type metallic glasses. Samples of the VITROPERM® magnetic ribbons were irradiated by Au, Xe and U ions at 11.1 MeV/A (per nucleon) and 5.9 MeV/A, respectively. Irradiation fluences from 1 × 1011 up to 1 × 1013 ions/cm2 were applied. In case of the Au and U ions, the total fluence was accumulated in one beamtime, whereas two separate beamtimes were used to accumulate the final fluence in case of the Xe ions. Relative change in the samples' magnetic susceptibility after and before irradiation was evaluated as a function of the irradiation fluence. The irradiation experiments were performed with the UNILAC accelerator at GSI Helmholtzzentrum für Schwerionenforschung GmbH. They were simulated in SRIM2010 in order to obtain ionization densities (electronic stopping, dE/dx) and dpa (displacements per atom) caused by the ion beams in the sample material. This paper focuses mainly on the results collected in experiments with the Xe ions and compares them with data obtained in earlier experiments using Au and U ions. Radiation hardness of VITROPERM® is compared with radiation hardness of VITROVAC® that was studied in previous experiments. The VITROPERM® samples showed less drop in magnetic susceptibility in comparison with the VITROVAC® ones, and this drop occurred at higher fluences. This indicates higher radiation hardness of VITROPERM® compared with VITROVAC®. In addition, heavier ions cause bigger change in magnetic susceptibility than the lighter ones. The effect can be roughly scaled with electronic stopping, which suggests that the main mechanism of radiation
Transmission of low-energy negative ions through insulating nanocapillaries
NASA Astrophysics Data System (ADS)
Zhang, Qi; Liu, Zhonglin; Li, Pengfei; Jin, Bo; Song, Guangyin; Jin, Dingkun; Niu, Ben; Wei, Long; Ha, Shuai; Xie, Yiming; Ma, Yue; Wan, Chengliang; Cui, Ying; Zhou, Peng; Zhang, Hongqiang; Chen, Ximeng
2018-04-01
A simulation is performed to study the transmission of low-energy C l- ions through A l2O3 nanocapillaries. For the trajectory simulations, there are several processes involved: the image forces induced by the projectile; the electrostatic force from the deposited charges; the scattering from the inner surface and charge exchange. The simulation reproduces the main features of the experiments; i.e., the double peak structure in the transmitted angular distribution and the transmitted fractions of C l- , C l+ , and C l0 were found in the charge state distribution. The transmitted C l- ions are centered around the beam direction while the transmitted fractions of C l0 and C l+ are centered around the tilt angles. The role of the deposited charge is also studied by simulations. With the deposited charge, it is found that C l- is dominant in the transmission and the majority of the ions, centered around the tilt angle, are mainly from the single deflection by the negative charge patches on the inner surfaces of the capillaries, and only a few directly transmitted C l- ions are centered around the incident direction. There are also a few transmitted fractions of C l0 and C l+ from close surface scatterings. In the case that there are no negative charge patches, the simulation agrees with the experiment in detail: The majority of the directly transmitted C l- ions are centered around the incident direction while only a few scattered C l- ions are centered around the tilt angle from the single close collisions with the inner surfaces of the capillaries. There is a portion, comparable to the transmitted fraction of C l- , of the transmitted fractions of C l0 and C l+ , centered around the tilt angle, from the single scatterings with the inner surfaces of the capillaries. This confirms that at the present experimental conditions there are most probably no negative charge patches formed to guide the negative ions through insulating A l2O3 nanocapillaries.
Iwase, H; Wiegel, B; Fehrenbacher, G; Schardt, D; Nakamura, T; Niita, K; Radon, T
2005-01-01
Measured neutron energy fluences from high-energy heavy ion reactions through targets several centimeters to several hundred centimeters thick were compared with calculations made using the recently developed general-purpose particle and heavy ion transport code system (PHITS). It was confirmed that the PHITS represented neutron production by heavy ion reactions and neutron transport in thick shielding with good overall accuracy.
NASA Astrophysics Data System (ADS)
Liang, Edison; Fu, Wen; Böttcher, Markus
2017-10-01
We present particle-in-cell simulation results of relativistic shear boundary layers between electron-ion and electron-positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron-positron spine surrounded by a slow-moving or stationary electron-ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. This is in stark contrast to the case of pure electron-ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Liang, Edison; Fu, Wen; Böttcher, Markus
We present particle-in-cell simulation results of relativistic shear boundary layers between electron–ion and electron–positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron–positron spine surrounded by a slow-moving or stationary electron–ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. Thismore » is in stark contrast to the case of pure electron–ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.« less
Recoil-ion momentum distributions for transfer ionization in fast proton-He collisions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schmidt, H.T.; Reinhed, P.; Schuch, R.
2005-07-15
We present high-luminosity experimental investigations of the transfer ionization (TI:p+He{yields}H{sup 0}+He{sup 2+}+e{sup -}) process in collisions between fast protons and neutral helium atoms in the earlier inaccessibly high-energy range 1.4-5.8 MeV. The protons were stored in the heavy-ion storage and cooler ring CRYRING, where they intersected a narrow supersonic helium gas jet. We discuss the longitudinal recoil-ion momentum distribution, as measured by means of cold-target recoil-ion momentum spectroscopy and find that this distribution splits into two completely separated peaks at the high end of our energy range. These separate contributions are discussed in terms of the earlier proposed Thomas TImore » (TTI) and kinematic TI mechansims. The cross section of the TTI process is found to follow a {sigma}{proportional_to}v{sup -b} dependence with b=10.78{+-}0.27 in accordance with the expected v{sup -11} asymptotic behavior. Further, we discuss the probability for shake-off accompanying electron transfer and the relation of this TI mechanism to photodouble ionization. Finally the influence of the initial-state electron velocity distribution on the TTI process is discussed.« less
Structure of an energetic narrow discrete arc
NASA Technical Reports Server (NTRS)
Mcfadden, J. P.; Carlson, C. W.; Boehm, M. H.
1990-01-01
Particle distributions, waves, dc electric fields, and magnetic fields were measured by two sounding rockets at altitudes of 950 and 430 km through an energetic (greater than 5 keV) narrow (about 10 km) stable discrete arc. Although the payloads' magnetic footprints were separated by only 50 km, differences in the arc's structure were observed including the spatial width, peak energy, and characteristic spectra. The energetic electron precipitation included both slowly varying isotropic fluxes that formed an inverted-V energy-time signature and rapidly varying field-aligned fluxes at or below the isotropic spectral peak. The isotropic precipitation had a flux discontinuity inside the arc indicating the arc was present on a boundary between two different magnetospheric plasmas. Dispersive and nondispersive bursts of field-aligned electrons were measured throughout the arc, appearing over broad energy ranges or as monoenergetic beams. Dispersive bursts gave variable source distances less than 8000 km. Plateauing of some of the most intense bursts suggests that waves stabilized these electrons. During the lower altitude arc crossing, the field-aligned component formed a separate inverted-V energy-time signature whose peak energy was half the isotropic peak energy.
Ultrahigh-Energy Density Lithium-Ion Cable Battery Based on the Carbon-Nanotube Woven Macrofilms.
Wu, Ziping; Liu, Kaixi; Lv, Chao; Zhong, Shengwen; Wang, Qinghui; Liu, Ting; Liu, Xianbin; Yin, Yanhong; Hu, Yingyan; Wei, Di; Liu, Zhongfan
2018-05-01
Moore's law predicts the performance of integrated circuit doubles every two years, lasting for more than five decades. However, the improvements of the performance of energy density in batteries lag far behind that. In addition, the poor flexibility, insufficient-energy density, and complexity of incorporation into wearable electronics remain considerable challenges for current battery technology. Herein, a lithium-ion cable battery is invented, which is insensitive to deformation due to its use of carbon nanotube (CNT) woven macrofilms as the charge collectors. An ultrahigh-tap density of 10 mg cm -2 of the electrodes can be obtained, which leads to an extremely high-energy density of 215 mWh cm -3 . The value is approximately seven times than that of the highest performance reported previously. In addition, the battery displays very stable rate performance and lower internal resistance than conventional lithium-ion batteries using metal charge collectors. Moreover, it demonstrates excellent convenience for connecting electronics as a new strategy is applied, in which both electrodes can be integrated into one end by a CNT macrorope. Such an ultrahigh-energy density lithium-ion cable battery provides a feasible way to power wearable electronics with commercial viability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Photoluminescence from narrow InAs-AlSb quantum wells
NASA Technical Reports Server (NTRS)
Brar, Berinder; Kroemer, Herbert; Ibbetson, James; English, John H.
1993-01-01
We report on photoluminescence spectra from narrow InAs-AlSb quantum wells. Strong, clearly resolved peaks for well widths from 2 to 8 monolayers were observed. Transmission electron micrographs show direct evidence for the structural quality of the quantum well structures. The transition energies of the narrowest wells suggest a strong influence of the AlSb X-barrier on the electronic states in the conduction band.
Ion energies in high power impulse magnetron sputtering with and without localized ionization zones
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yang, Yuchen; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720; Tanaka, Koichi
2015-03-23
High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.
Ion peak narrowing by applying additional AC voltage (ripple voltage) to FAIMS extractor electrode.
Pervukhin, Viktor V; Sheven, Dmitriy G
2010-01-01
The use of a non-uniform electric field in a high-field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer increases sensitivity but decreases resolution. The application of an additional AC voltage to the extractor electrode ("ripple" voltage, U(ripple)) can overcome this effect, which decreases the FAIMS peak width. In this approach, the diffusion ion loss remains minimal in the non-uniform electric field in the cylindrical part of the device, and all ion losses under U(ripple) occur in a short portion of their path. Application of the ripple voltage to the extractor electrode is twice as efficient as the applying of U(ripple) along the total length of the device. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.
Azkar Ul Hasan, Syed; Jung, Youngdo; Kim, Seonggi; Jung, Cho-Long; Oh, Sunjong; Kim, Junhee; Lim, Hyuneui
2016-01-12
High sensitive flexible and wearable devices which can detect delicate touches have attracted considerable attentions from researchers for various promising applications. This research was aimed at enhancing the sensitivity of a MWCNT/PDMS piezoresistive tactile sensor through modification of its surface texture in the form of micropillars on MWCNT/PDMS film and subsequent low energy Ar⁺ ion beam treatment of the micropillars. The introduction of straight micropillars on the MWCNT/PDMS surface increased the sensitivity under gentle touch. Low energy ion beam treatment was performed to induce a stiff layer on the exposed surface of the micropillar structured MWCNT/PDMS film. The low energy ion bombardment stabilized the electrical properties of the MWCNT/PDMS surface and tuned the curvature of micropillars according to the treatment conditions. The straight micropillars which were treated by Ar⁺ ion with an incident angle of 0° demonstrated the enhanced sensitivity under normal pressure and the curved micropillars which were treated with Ar⁺ ion with an incident angle of 60° differentiated the direction of an applied shear pressure. The ion beam treatment on micropillar structured MWCNT/PDMS tactile sensors can thus be applied to reliable sensing under gentle touch with directional discrimination.
NASA Astrophysics Data System (ADS)
Gann, V. V.; Tolstolutskaya, G. D.
2008-08-01
An experimental study confirms the possibility of nuclear fusion reactions initiating in metal-deuterium targets by bombarding them with ions that are not the reagents of the fusion reaction, in particular, with noble gas ions. The yields of (d,d) and (d,t) reactions were measured as functions of energy (0.4-3.2 MeV) and mass of incident ions (He +, Ne +, Ar +, Kr + and Xe +). Irradiation by heavy ions produced a number of energetic deuterium atoms in the deuteride and deuterium + tritium metal targets. At ion energies of ˜0.1-1 MeV the d-d reaction yields are relatively high. A model of nuclear fusion reaction cross-sections in atomic collision cascades initiated by noble gas ion beam in metal-deuterium target is developed. The method for calculation tritium or deuterium recoil fluxes and the yield of d-d fusion reaction in subsequent collisions was proposed. It was shown that D(d,p)t and D(t,n) 4He reactions mainly occur in energy region of the recoiled D-atom from 10 keV to 250 keV. The calculated probabilities of d-d and d-t fusion reactions were found to be in a good agreement with the experimental data.
Carvalho, Nathalia F; Pliego, Josefredo R
2015-10-28
Absolute single-ion solvation free energy is a very useful property for understanding solution phase chemistry. The real solvation free energy of an ion depends on its interaction with the solvent molecules and on the net potential inside the solute cavity. The tetraphenyl arsonium-tetraphenyl borate (TATB) assumption as well as the cluster-continuum quasichemical theory (CC-QCT) approach for Li(+) solvation allows access to a solvation scale excluding the net potential. We have determined this free energy scale investigating the solvation of the lithium ion in water (H2O), acetonitrile (CH3CN) and dimethyl sulfoxide (DMSO) solvents via the CC-QCT approach. Our calculations at the MP2 and MP4 levels with basis sets up to the QZVPP+diff quality, and including solvation of the clusters and solvent molecules by the dielectric continuum SMD method, predict the solvation free energy of Li(+) as -116.1, -120.6 and -123.6 kcal mol(-1) in H2O, CH3CN and DMSO solvents, respectively (1 mol L(-1) standard state). These values are compatible with the solvation free energy of the proton of -253.4, -253.2 and -261.1 kcal mol(-1) in H2O, CH3CN and DMSO solvents, respectively. Deviations from the experimental TATB scale are only 1.3 kcal mol(-1) in H2O and 1.8 kcal mol(-1) in DMSO solvents. However, in the case of CH3CN, the deviation reaches a value of 9.2 kcal mol(-1). The present study suggests that the experimental TATB scale is inconsistent for CH3CN. A total of 125 values of the solvation free energy of ions in these three solvents were obtained. These new data should be useful for the development of theoretical solvation models.
Method for Predicting the Energy Characteristics of Li-Ion Cells Designed for High Specific Energy
NASA Technical Reports Server (NTRS)
Bennett, William, R.
2012-01-01
Novel electrode materials with increased specific capacity and voltage performance are critical to the NASA goals for developing Li-ion batteries with increased specific energy and energy density. Although performance metrics of the individual electrodes are critically important, a fundamental understanding of the interactions of electrodes in a full cell is essential to achieving the desired performance, and for establishing meaningful goals for electrode performance in the first place. This paper presents design considerations for matching positive and negative electrodes in a viable design. Methods for predicting cell-level performance, based on laboratory data for individual electrodes, are presented and discussed.
ELISA - an electrostatic storage ring for low-energy ions
NASA Astrophysics Data System (ADS)
Pape Moeller, Soeren
1997-05-01
The design of a new type of storage ring for low-energy ions using electrostatic deflection and focusing devices is described. Electrostatic bends and quadrupoles are used since they are more efficient than magnetic ones for low-velocity heavy ions. Furthermore, electrostatic devices are more compact and easier to construct than magnetic devices. In comparison to an electromagnetic trap, one important advantage of the elecrostatic ring is the easy access to the circulating beam and its decay products. These and other features, e.g. no magnetic fields, makes such storage devices attractive for many atomic-physics experiments. Also neigboring fields as chemistry and biology might benefit from such an relatively inexpensive device. One important difference between an electrostatic and a magnetic ring is, that the longitudinal energy is not conserved for the electrostatic ring. The actual ring will have a race-track shape as defined by two straight sections each with two quadrupole doublets connected by 180-degrees bends. The bends will consist of 160-degrees spherical deflection plates surrounded by two parallel plate 10-degrees bends. The storage ring ELISA, currently being built, will have a circumference of 6 meters. The first beam tests will take place during summer 1996.
Band-gap narrowing and magnetic behavior of Ni-doped Ba(Ti0.875Ce0.125)O3 thin films
NASA Astrophysics Data System (ADS)
Zhou, Wenliang; Deng, Hongmei; Yu, Lu; Yang, Pingxiong; Chu, Junhao
2015-11-01
Band-gap narrowing and magnetic effects have been observed in a Ni-doped Ba(Ti0.875Ce0.125)O3 (BTC) thin film. Structural characterizations and microstructural analysis show that the as-prepared Ba(Ti0.75Ce0.125Ni0.125)O3-δ (BTCN) thin film exhibits a cubic perovskite structure with an average grain size of 25 nm. The Ce doping at the Ti-site results in an increasing perovskite volume to favour an O-vacancy-stabilized Ni2+ substitution. Raman spectroscopy, however, shows the cubic symmetry of crystalline structures is locally lowered by the presence of dopants, significantly deviating from the ideal Pm3m space group. Moreover, BTCN presents a narrowed band-gap, much smaller than that of BaTiO3 and BTC, due to new states of both the highest occupied molecular orbital and the lowest unoccupied molecular orbital in an electronic structure with the presence of Ni. Also, magnetic enhancement driven by co-doping has been confirmed in the films, which mainly stems from the exchange interaction of Ni2+ ions via an electron trapped in a bridging oxygen vacancy. These findings may open an avenue to discover and design optimal perovskite compounds for solar-energy devices and information storage.
NASA Astrophysics Data System (ADS)
Christenson, M.; Stemmley, S.; Jung, S.; Mettler, J.; Sang, X.; Martin, D.; Kalathiparambil, K.; Ruzic, D. N.
2017-08-01
The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) experiment at the University of Illinois is a gas-puff driven, theta-pinch plasma source that is used as a test stand for off-normal plasma events incident on materials in the edge and divertor regions of a tokamak. The ion temperatures and resulting energy distributions are crucial for understanding how well a TELS pulse can simulate an extreme event in a larger, magnetic confinement device. A retarding field energy analyzer (RFEA) has been constructed for use with such a transient plasma due to its inexpensive and robust nature. The innovation surrounding the use of a control analyzer in conjunction with an actively sampling analyzer is presented and the conditions of RFEA operation are discussed, with results presented demonstrating successful performance under extreme conditions. Such extreme conditions are defined by heat fluxes on the order of 0.8 GW m-2 and on time scales of nearly 200 μs. Measurements from the RFEA indicate two primary features for a typical TELS discharge, following closely with the pre-ionizing coaxial gun discharge characteristics. For the case using the pre-ionization pulse (PiP) and the theta pinch, the measured ion signal showed an ion temperature of 23.3 ± 6.6 eV for the first peak and 17.6 ± 1.9 eV for the second peak. For the case using only the PiP, the measured signal showed an ion temperature of 7.9 ± 1.1 eV for the first peak and 6.6 ± 0.8 eV for the second peak. These differences illustrate the effectiveness of the theta pinch for imparting energy on the ions. This information also highlights the importance of TELS as being one of the few linear pulsed plasma sources whereby moderately energetic ions will strike targets without the need for sample biasing.
Christenson, M; Stemmley, S; Jung, S; Mettler, J; Sang, X; Martin, D; Kalathiparambil, K; Ruzic, D N
2017-08-01
The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) experiment at the University of Illinois is a gas-puff driven, theta-pinch plasma source that is used as a test stand for off-normal plasma events incident on materials in the edge and divertor regions of a tokamak. The ion temperatures and resulting energy distributions are crucial for understanding how well a TELS pulse can simulate an extreme event in a larger, magnetic confinement device. A retarding field energy analyzer (RFEA) has been constructed for use with such a transient plasma due to its inexpensive and robust nature. The innovation surrounding the use of a control analyzer in conjunction with an actively sampling analyzer is presented and the conditions of RFEA operation are discussed, with results presented demonstrating successful performance under extreme conditions. Such extreme conditions are defined by heat fluxes on the order of 0.8 GW m -2 and on time scales of nearly 200 μs. Measurements from the RFEA indicate two primary features for a typical TELS discharge, following closely with the pre-ionizing coaxial gun discharge characteristics. For the case using the pre-ionization pulse (PiP) and the theta pinch, the measured ion signal showed an ion temperature of 23.3 ± 6.6 eV for the first peak and 17.6 ± 1.9 eV for the second peak. For the case using only the PiP, the measured signal showed an ion temperature of 7.9 ± 1.1 eV for the first peak and 6.6 ± 0.8 eV for the second peak. These differences illustrate the effectiveness of the theta pinch for imparting energy on the ions. This information also highlights the importance of TELS as being one of the few linear pulsed plasma sources whereby moderately energetic ions will strike targets without the need for sample biasing.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chakraborty, Subrata; Vijay, Amrendra, E-mail: avijay@iitm.ac.in
Using a second-quantized many-electron Hamiltonian, we obtain (a) an effective Hamiltonian suitable for materials whose electronic properties are governed by a set of strongly correlated bands in a narrow energy range and (b) an effective spin-only Hamiltonian for magnetic materials. The present Hamiltonians faithfully include phonon and spin-related interactions as well as the external fields to study the electromagnetic response properties of complex materials and they, in appropriate limits, reduce to the model Hamiltonians due to Hubbard and Heisenberg. With the Hamiltonian for narrow-band strongly correlated materials, we show that the spin-orbit interaction provides a mechanism for metal-insulator transition, whichmore » is distinct from the Mott-Hubbard (driven by the electron correlation) and the Anderson mechanism (driven by the disorder). Next, with the spin-only Hamiltonian, we demonstrate the spin-orbit interaction to be a reason for the existence of antiferromagnetic phase in materials which are characterized by a positive isotropic spin-exchange energy. This is distinct from the Néel-VanVleck-Anderson paradigm which posits a negative spin-exchange for the existence of antiferromagnetism. We also find that the Néel temperature increases as the absolute value of the spin-orbit coupling increases.« less
Narrow-band radio flares from red dwarf stars
NASA Technical Reports Server (NTRS)
White, Stephen M.; Kundu, Mukul R.; Jackson, Peter D.
1986-01-01
VLA observations of narrow-band behavior in 20 cm flares from two red dwarf stars, L726 - 8A and AD Leo, are reported. The flare on L726 - 8A was observed at 1415 and 1515 MHz; the flux and the evolution differed significantly at the two frequencies. The flare on AD Leo lasted for 2 hr at 1415 MHz but did not appear at 1515 MHz. The AD Leo flare appears to rule out a source drifting through the stellar corona and is unlikely to be due to plasma emission. In the cyclotron maser model the narrow-band behavior reflects the range of magnetic fields present within the source. The apparent constancy of this field for 2 hr is difficult to understand if magnetic reconnection is the source of energy for the flare. The consistent polarization exhibited by red dwarf flares at 20 cm may be related to stellar activity cycles, and changes in this polarization will permit measuring the length of these cycles.
The effects on γ-LiAlO2 induced by nuclear energy losses during Ga ions implantation
NASA Astrophysics Data System (ADS)
Zhang, Jing; Song, Hong-Lian; Qiao, Mei; Yu, Xiao-Fei; Wang, Tie-Jun; Wang, Xue-Lin
2017-09-01
To explore the evolution of γ-LiAlO2 under ion irradiation at low energy, we implanted Ga ions of 30, 80 and 150 keV at fluences of 1 × 1014 and 1 × 1015 ions/cm2 in z-cut γ-LiAlO2 samples, respectively. The implantation resulted in damage regions dominated by nuclear energy losses at depth of 232 Å, 514 Å, and 911 Å beneath the surface, respectively, which was simulated by the Stopping and Range of Ions in Matter program. The irradiated γ-LiAlO2 were characterized with atomic force microscope, Raman spectroscopy, X-ray diffraction and Rutherford backscattering in a channeling mode for morphology evolution, structure information and damage profiles. The interesting and partly abnormal results showed the various behaviors in modification of surface by Ga ions implantation.
NASA Astrophysics Data System (ADS)
Chakraborty, Subha; Huang, Mengbing
2017-10-01
We report on measurements and analysis of ionoluminescence properties of pure polystyrene films and polystyrene films doped with four types of fluorophores in low kinetic energies (50-350 keV) of ion irradiation. We have developed a theoretical model to understand the experimentally observed ionoluminescence behaviors in terms of scintillation yield from individual ion tracks, photophysical energy transfer mechanisms, and irradiation-induced defects. A comparison of the model and experimental results suggests that singlet up-conversion resulting from triplet-triplet annihilation processes may be responsible for enhanced singlet emission of the fluorophores at high ion beam flux densities. Energy transfer from the polystyrene matrix to the fluorophore molecules has been identified as an effective pathway to increasing the fluorescence efficiency in the doped scintillator films.
NASA Astrophysics Data System (ADS)
Thiel, Charles Warren
There are a vast number of applications for rare-earth-activated materials and much of today's cutting-edge optical technology and emerging innovations are enabled by their unique properties. In many of these applications, interactions between the rare-earth ion and the host material's electronic states can enhance or inhibit performance and provide mechanisms for manipulating the optical properties. Continued advances in these technologies require knowledge of the relative energies of rare-earth and crystal band states so that properties of available materials may be fully understood and new materials may be logically developed. Conventional and resonant electron photoemission techniques were used to measure 4f electron and valence band binding energies in important optical materials, including YAG, YAlO3, and LiYF4. The photoemission spectra were theoretically modeled and analyzed to accurately determine relative energies. By combining these energies with ultraviolet spectroscopy, binding energies of excited 4fN-15d and 4fN+1 states were determined. While the 4fN ground-state energies vary considerably between different trivalent ions and lie near or below the top of the valence band in optical materials, the lowest 4f N-15d states have similar energies and are near the bottom of the conduction band. As an example for YAG, the Tb3+ 4f N ground state is in the band gap at 0.7 eV above the valence band while the Lu3+ ground state is 4.7 eV below the valence band maximum; however, the lowest 4fN-15d states are 2.2 eV below the conduction band for both ions. We found that a simple model accurately describes the binding energies of the 4fN, 4fN-1 5d, and 4fN+1 states. The model's success across the entire rare-earth series indicates that measurements on two different ions in a host are sufficient to predict the energies of all rare-earth ions in that host. This information provides new insight into electron transfer transitions, luminescence quenching, and valence
NASA Technical Reports Server (NTRS)
Berthelier, J. J.; Illiano, J. M.; Hodges, R. R.; Krankowsky, D.; Eberhardt, P.; Laemmerzahl, P.; Hoffman, J. H.; Herrwerth, I.; Woweries, J.; Dolder, U.
1986-01-01
During the early phase of the Giotto encounter with comet Halley, at distances from the nucleus greater than 350,000 km, the neutral mass spectrometer was operated in a mode allowing the measurement of low energy ions. Data reveal two important features of the outer coma: the presence of a sharp discontinuity in the plasma flow at 550,000 km from the nucleus which results in a significant decrease of the plasma flow accompanied by an increase in temperature; and the detection of newly born ions identified as O(+) and CO(+), at distances from the comet greater than 800,000 km.
NASA Astrophysics Data System (ADS)
Yoshida, Y.; Matsumura, A.; Higeta, K.; Inoue, T.; Shimizu, S.; Motonami, Y.; Sato, M.; Sadahiro, T.; Fujii, K.
1991-07-01
The hardness depth profiles of cemented carbides which were implanted with high-energy B + ions have been estimated using a dynamic microhardness tester. The B + implantations into (16% Co)-cemented WC alloys were carried out under conditions where the implantation energies were 1-3 MeV and the fluences 1 × 10 17-1 × 10 18ions/cm 2. The profiles show that the implanted layer becomes harder as fluences are chosen at higher values and there is a peak at a certain depth which depends on the implantation energy. In X-ray diffraction (XRD) studies of the implanted surface the broadened refraction peaks of only WC and Co are detected and the increments of lattice strain and of residual stress in the near-surface region are observed. It is supposed that the hardening effect should be induced by an increase in residual stress produced by lattice strain. The hardness depth profile in successive implantation of ions with different energies agrees with the compounded profile of each one of the implantations. It is concluded that the hardness depth profile can be controlled under adequate conditions of implantation.
Transverse energy per charged particle in heavy-ion collisions: Role of collective flow
NASA Astrophysics Data System (ADS)
Kumar Tiwari, Swatantra; Sahoo, Raghunath
2018-03-01
The ratio of (pseudo)rapidity density of transverse energy and the (pseudo)rapidity density of charged particles, which is a measure of the mean transverse energy per particle, is an important observable in high energy heavy-ion collisions. This ratio reveals information about the mechanism of particle production and the freeze-out criteria. Its collision energy and centrality dependence is almost similar to the chemical freeze-out temperature until top Relativistic Heavy-Ion Collider (RHIC) energy. The Large Hadron Collider (LHC) measurement at √{s_{NN}} = 2.76 TeV brings up new challenges towards understanding the phenomena like gluon saturation and role of collective flow, etc. being prevalent at high energies, which could contribute to the above observable. Statistical Hadron Gas Model (SHGM) with a static fireball approximation has been successful in describing both the centrality and energy dependence until top RHIC energies. However, the SHGM predictions for higher energies lie well below the LHC data. In order to understand this, we have incorporated collective flow in an excluded-volume SHGM (EV-SHGM). Our studies suggest that the collective flow plays an important role in describing E T/ N ch and it could be one of the possible parameters to explain the rise observed in E T/ N ch from RHIC to LHC energies. Predictions are made for E T/ N ch , participant pair normalized-transverse energy per unit rapidity and the Bjorken energy density for Pb+Pb collisions at √{s_{NN}} = 5.02 TeV at the Large Hadron Collider.
Treatment of PVC using an alternative low energy ion bombardment procedure
NASA Astrophysics Data System (ADS)
Rangel, Elidiane C.; dos Santos, Nazir M.; Bortoleto, José Roberto R.; Durrant, Steven F.; Schreiner, Wido H.; Honda, Roberto Y.; Rangel, Rita de Cássia C.; Cruz, Nilson C.
2011-12-01
In many applications, polymers have progressively substituted traditional materials such as ceramics, glasses, and metals. Nevertheless, the use of polymeric materials is still limited by their surface properties. Frequently, selective modifications are necessary to suit the surface to a given application. Amongst the most common treatments, plasma immersion ion implantation (PIII) has attracted the attention of many researchers owing to its versatility and practicality. This method, however, requires a power supply to provide high voltage (tens of kV) negative pulses, with a controlled duty cycle, width and frequency. Owing to this, the implementation of PIII on the industrial scale can become economically inviable. In this work, an alternative plasma treatment that enables low energy ion bombardment without the need of a high voltage pulse generator is presented. To evaluate the efficiency of the treatment of polymers, polyvinylchloride, PVC, specimens were exposed to 5 Pa argon plasmas for 3600 s, at excitation powers, P, of between 10 and 125 W. Through contact angle and atomic force microscopy data, the influence of P on the wettability, surface free energy and roughness of the samples was studied. Surface chemical composition was measured by X-ray photoelectron spectroscopy, XPS. To evaluate the effect of aging under atmospheric conditions, contact angle and XPS measurements were performed one and 1334 days after the treatment. The plasma potential and ion density around the driven electrode were determined from Langmuir probe measurements while the self-bias potential was derived with the aid of an oscilloscope. From these data it was possible to estimate the mean energy of ions bombarding the PVC surface. Chlorine, carbon and oxygen contamination were detected on the surface of the as-received PVC. Upon exposure to the plasma, the proportion of chlorine was observed to decrease while that of oxygen increased. Consequently, the wettability and surface energy
Jockusch, Rebecca A.; Schnier, Paul D.; Price, William D.; Strittmatter, Eric. F.; Demirev, Plamen A.; Williams*, Evan R.
2005-01-01
Blackbody infrared radiative dissociation spectra of the (M + 5H)5+ through (M + 11H)11+ ions of the protein ubiquitin (8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrometer. The 5+ ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+ charge state dissociates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states. The y and b ions are formed by cleavage of the backbone amide bond on the C-terminal side of acidic residues exclusively, with cleavage adjacent to aspartic acid favored. Thermal unimolecular dissociation rate constants for the dissociation of each of these charge states were measured. From the temperature dependence of these rates, Arrhenius activation parameters in the rapid energy exchange limit are obtained. The activation energies (Ea) and preexponential factors (A) for the 5+, 8+, and 9+ ions are 1.2 eV and 1012 s−1, respectively. These values for the 6+ and 7+ ions are 0.9–1.0 eV and 109 s−1, and those for the 10+ and 11+ ions are 1.6 eV and 1016–1017 s−1. Thus, with the exception of the 5+ ion, the higher charge states of ubiquitin have larger dissociation activation energies than the lower charge states. The different A factors observed for production of y and b ions from different precursor charge states indicate that they are formed by different mechanisms, ranging from relatively complex rearrangements to direct bond cleavages. These results clearly demonstrate that the relative dissociation rates of large biomolecule ions by themselves are not necessarily a reliable indicator of their relative dissociation energies, even when similar fragment ions are formed. PMID:9075403
Jockusch, R A; Schnier, P D; Price, W D; Strittmatter, E F; Demirev, P A; Williams, E R
1997-03-15
Blackbody infrared radiative dissociation spectra of the (M + 5H)5+ through (M + 11H)11+ ions of the protein ubiquitin (8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrometer. The 5+ ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+ charge state dissociates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states. The y and b ions are formed by cleavage of the backbone amide bond on the C-terminal side of acidic residues exclusively, with cleavage adjacent to aspartic acid favored. Thermal unimolecular dissociation rate constants for the dissociation of each of these charge states were measured. From the temperature dependence of these rates, Arrhenius activation parameters in the rapid energy exchange limit are obtained. The activation energies (Ea) and preexponential factors (A) for the 5+, 8+, and 9+ ions are 1.2 eV and 10(12) s-1, respectively. These values for the 6+ and 7+ ions are 0.9-1.0 eV and 10(9) s-1, and those for the 10+ and 11+ ions are 1.6 eV and 10(16)-10(17) s-1. Thus, with the exception of the 5+ ion, the higher charge states of ubiquitin have larger dissociation activation energies than the lower charge states. The different A factors observed for production of y and b ions from different precursor charge states indicate that they are formed by different mechanisms, ranging from relatively complex rearrangements to direct bond cleavages. These results clearly demonstrate that the relative dissociation rates of large biomolecule ions by themselves are not necessarily a reliable indicator of their relative dissociation energies, even when similar fragment ions are formed.
NASA Technical Reports Server (NTRS)
Lin, R. P.; Anderson, K. A.; Ashford, S.; Carlson, C.; Curtis, D.; Ergun, R.; Larson, D.; McFadden, J.; McCarthy, M.; Parks, G. K.
1995-01-01
The 3-D Plasma and Energetic Particle instrument on the GGS Wind spacecraft (launched November 1, 1994) is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. Three pairs of double-ended telescopes, each with two or three closely sandwiched passivated ion implanted silicon detectors measure electrons and ions from approximately 20 keV to greater than or equal to 300 keV. Four top-hat symmetrical spherical section electrostatic analyzers with microchannel plate detectors, a large and a small geometric factor analyzer for electrons and a similar pair for ions, cover from approximately 3 eV to 30 keV. We present preliminary observations of the electron and ion distributions in the absence of obvious solar impulsive events and upstream particles. The quiet time electron energy spectrum shows a smooth approximately power law fall-off extending from the halo population at a few hundred eV to well above approximately 100 keV The quiet time ion energy spectrum also shows significant fluxes over this energy range. Detailed 3-D distributions and their temporal variations will be presented.
NASA Technical Reports Server (NTRS)
Patterson, James D.
1996-01-01
We have used a Green's function technique to calculate the energy levels and formation energy of deep defects in the narrow gap semiconductors mercury cadmium telluride (MCT), mercury zinc telluride (MZT) and mercury zinc selenide (MZS). The formation energy is calculated from the difference between the total energy with an impurity cluster and the total energy for the perfect crystal. Substitutional (including antisite), interstitial (self and foreign), and vacancy deep defects are considered. Relaxation effects are calculated (with molecular dynamics). By use of a pseudopotential, we generalize the ideal vacancy model so as to be able to consider relaxation for vacancies. Different charge states are considered and the charged state energy shift (as computed by a modified Haldane-Anderson model) can be twice that due to relaxation. Different charged states for vacancies were not calculated to have much effect on the formation energy. For all cases we find deep defects in the energy gap only for cation site s-like orbitals or anion site p-like orbitals, and for the substitutional case only the latter are appreciably effected by relaxation. For most cases for MCT, MZT, MZS, we consider x (the concentration of Cd or Zn) in the range appropriate for a band gap of 0.1 eV. For defect energy levels, the absolute accuracy of our results is limited, but the precision is good, and hence chemical trends are accurately predicted. For the same reason, defect formation energies are more accurately predicted than energy level position. We attempt, in Appendix B, to calculate vacancy formation energies using relatively simple chemical bonding ideas due to Harrison. However, these results are only marginally accurate for estimating vacancy binding energies. Appendix C lists all written reports and publications produced for the grant. We include abstracts and a complete paper that summarizes our work which is not yet available.
Cytogenetic effects of high-energy iron ions: dependence on shielding thickness and material.
Durante, M; George, K; Gialanella, G; Grossi, G; La Tessa, C; Manti, L; Miller, J; Pugliese, M; Scampoli, P; Cucinotta, F A
2005-10-01
We report results for chromosomal aberrations in human peripheral blood lymphocytes after they were exposed to high-energy iron ions with or without shielding at the HIMAC, AGS and NSRL accelerators. Isolated lymphocytes were exposed to iron ions with energies between 200 and 5000 MeV/nucleon in the 0.1-1-Gy dose range. Shielding materials consisted of polyethylene, lucite (PMMA), carbon, aluminum and lead, with mass thickness ranging from 2 to 30 g/cm2. After exposure, lymphocytes were stimulated to grow in vitro, and chromosomes were prematurely condensed using a phosphatase inhibitor (calyculin A). Aberrations were scored using FISH painting. The yield of total interchromosomal exchanges (including dicentrics, translocations and complex rearrangements) increased linearly with dose or fluence in the range studied. Shielding decreased the effectiveness per unit dose of iron ions. The highest RBE value was measured with the 1 GeV/nucleon iron-ion beam at NSRL. However, the RBE for the induction of aberrations apparently is not well correlated with the mean LET. When shielding thickness was increased, the frequency of aberrations per particle incident on the shield increased for the 500 MeV/nucleon ions and decreased for the 1 GeV/nucleon ions. Maximum variation at equal mass thickness was obtained with light materials (polyethylene, carbon or PMMA). Variations in the yield of chromosomal aberrations per iron particle incident on the shield follow variations in the dose per incident particle behind the shield but can be modified by the different RBE of the mixed radiation field produced by nuclear fragmentation. The results suggest that shielding design models should be benchmarked using both physics and biological data.
Heavy ion charge-state distribution effects on energy loss in plasmas.
Barriga-Carrasco, Manuel D
2013-10-01
According to dielectric formalism, the energy loss of the heavy ion depends on its velocity and its charge density. Also, it depends on the target through its dielectric function; here the random phase approximation is used because it correctly describes fully ionized plasmas at any degeneracy. On the other hand, the Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its mean charge state [Q]. This latter criterion implies that the mean charge state depends on the electron density and temperature of the plasma. Also, the initial charge state of the heavy ion is crucial for calculating [Q] inside the plasma. Comparing our models and estimations with experimental data, a very good agreement is found. It is noticed that the energy loss in plasmas is higher than that in the same cold gas cases, confirming the well-known enhanced plasma stopping (EPS). In this case, EPS is only due to the increase in projectile effective charge Q(eff), which is obtained as the ratio between the energy loss of each heavy ion and that of the proton in the same plasma conditions. The ratio between the effective charges in plasmas and in cold gases is higher than 1, but it is not as high as thought in the past. Finally, another significant issue is that the calculated effective charge in plasmas Q(eff) is greater than the mean charge state [Q], which is due to the incorporation of the BK charge distribution. When estimations are performed without this distribution, they do not fit well with experimental data.
Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H
2015-11-01
A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.
NASA Astrophysics Data System (ADS)
Rout, Bibhudutta; Dhoubhadel, Mangal S.; Poudel, Prakash R.; Kummari, Venkata C.; Lakshantha, Wickramaarachchige J.; Manuel, Jack E.; Bohara, Gyanendra; Szilasi, Szabolcs Z.; Glass, Gary A.; McDaniel, Floyd D.
2014-02-01
The University of North Texas (UNT) Ion Beam Modification and Analysis Laboratory (IBMAL) has four particle accelerators including a National Electrostatics Corporation (NEC) 9SDH-2 3 MV tandem Pelletron, a NEC 9SH 3 MV single-ended Pelletron, and a 200 kV Cockcroft-Walton. A fourth HVEC AK 2.5 MV Van de Graaff accelerator is presently being refurbished as an educational training facility. These accelerators can produce and accelerate almost any ion in the periodic table at energies from a few keV to tens of MeV. They are used to modify materials by ion implantation and to analyze materials by numerous atomic and nuclear physics techniques. The NEC 9SH accelerator was recently installed in the IBMAL and subsequently upgraded with the addition of a capacitive-liner and terminal potential stabilization system to reduce ion energy spread and therefore improve spatial resolution of the probing ion beam to hundreds of nanometers. Research involves materials modification and synthesis by ion implantation for photonic, electronic, and magnetic applications, micro-fabrication by high energy (MeV) ion beam lithography, microanalysis of biomedical and semiconductor materials, development of highenergy ion nanoprobe focusing systems, and educational and outreach activities. An overview of the IBMAL facilities and some of the current research projects are discussed.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Abraham, John Bishoy Sam; Pacheco, Jose L.; Aguirre, Brandon Adrian
2016-08-09
We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. In conclusion, the ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantationmore » process.« less
Low-Energy Electrons Emitted in Ion Collisions with Thin Foils
NASA Astrophysics Data System (ADS)
Kraemer, Michael; Kozhuharov, Christophor; Durante, Marco; Hagmann, Siegbert; Kraft, Gerhard; Lineva, Natallia
The realistic description of radiation damage after charged particle passage is an ongoing issue for both radiotherapy as well as space applications. In both areas of applied radiological science, living as well as nonliving matter is exposed to ionizing radiation, and it is of vital interest to predict the responses of structures like cells, detectors or electronic devices. In ion beam radiotherapy, for example, the Local Effect Model (LEM) is being used to calculate radiobiological effects with so far unprecedented versatility. This has been shown in the GSI radiotherapy pilot project and consequently this model has become the "industry standard" for treatment planning in subsequent commercial ion radiotherapy sites. The model has also been extended to nonliving matter, i.e. to describe the response of solid state detectors such as TLDs and films. A prerequisite for this model (and possibly similar ones) is the proper description of microscopic track structure and energy deposition. In particular, the area at a very low distance (¡20 nm) from the ion path needs special attention due to the locally very high dose and the rather limited experimental evidence for the shape of the dose distribution. The dose distribution at low distances is inevitably associated with the creation and transport of low-energy (sub-keV) electrons. While some data, elementary cross sections as well as dose distributions, exist for gaseous media, i.e. under single collision conditions, experimental data for the condensed phase are scarce. We have, therefore, launched a project aimed at systematic research of the energy and angular distributions of low-energy (sub-keV) electrons emitted from solids. These investigations com-prise creation as well as transport of low-energy electrons under multiple collision conditions and hence require accounting for the properties of the target, both bulk and surface, i.e. for the inherent inhomogeneity of the thickness and for the surface roughness. To
Precision Spectroscopy on Single Cold Trapped Molecular Nitrogen Ions
NASA Astrophysics Data System (ADS)
Hegi, Gregor; Najafian, Kaveh; Germann, Matthias; Sergachev, Ilia; Willitsch, Stefan
2016-06-01
The ability to precisely control and manipulate single cold trapped particles has enabled spectroscopic studies on narrow transitions of ions at unprecedented levels of precision. This has opened up a wide range of applications, from tests of fundamental physical concepts, e.g., possible time-variations of fundamental constants, to new and improved frequency standards. So far most of these experiments have concentrated on atomic ions. Recently, however, attention has also been focused on molecular species, and molecular nitrogen ions have been identified as promising candidates for testing a possible time-variation of the proton/electron mass ratio. Here, we report progress towards precision-spectroscopic studies on dipole-forbidden vibrational transitions in single trapped N2+ ions. Our approach relies on the state-selective generation of single N2+ ions, subsequent infrared excitation using high intensity, narrow-band quantum-cascade lasers and a quantum-logic scheme for non-destructive state readout. We also characterize processes limiting the state lifetimes in our experiment, which impair the measurement fidelity. P. O. Schmidt et. al., Science 309 (2005), 749. M. Kajita et. al., Phys. Rev. A 89 (2014), 032509 M. Germann , X. Tong, S. Willitsch, Nature Physics 10 (2014), 820. X. Tong, A. Winney, S. Willitsch, Phys. Rev. Lett. 105 (2010), 143001
NASA Astrophysics Data System (ADS)
Youroukov, S.; Kitova, S.; Danev, G.
2008-05-01
The possibility is studied of growing thin silicon oxynitride films by e-gun evaporation of SiO and SiO2 together with concurrent bombardment with low energy N2+ ions from a cyclotron resonance (ECR) source at room temperature of substrates. The degree of nitridation and oxidation of the films is investigated by means of X-ray spectroscopy. The optical characteristics of the films, their environmental stability and adhesion to different substrates are examined. The results obtained show than the films deposited are transparent. It is found that in the case of SiO evaporation with concurrent N2+ ion bombardment, reactive implantation of nitrogen within the films takes place at room temperature of the substrate with the formation of a new silicon oxynitride compound even at low ion energy (150-200 eV).
Electrokinetic ion breakdown in a nanochannel
NASA Astrophysics Data System (ADS)
Wang, Jun-yao; Xu, Zheng
2016-07-01
In this paper, the electrokinetic ion breakdown in a nanochannel is investigated. The Poisson-Nernst-Planck equations are employed to simulate the influence of the voltage on the concentration. Both theoretical research and experiments show that increasing the voltage can promote the ion concentration, but high voltage will break up the repulsion effect of the electric double layer and bring the concentration down. For a given micro-nanochannel, the ion concentration has a peak value corresponding with a peak voltage. Narrowing the width of a nanochannel improves the peak voltage and the peak concentration. The results will be beneficial to research the internal discipline of electrokinetic concentration.
Du, Zhijia; Wood, David L.; Daniel, Claus; ...
2017-02-09
We present that increasing electrode thickness, thus increasing the volume ratio of active materials, is one effective method to enable the development of high energy density Li-ion batteries. In this study, an energy density versus power density optimization of LiNi 0.8Co 0.15Al 0.05O 2 (NCA)/graphite cell stack was conducted via mathematical modeling. The energy density was found to have a maximum point versus electrode thickness (critical thickness) at given discharging C rates. The physics-based factors that limit the energy/power density of thick electrodes were found to be increased cell polarization and underutilization of active materials. The latter is affected bymore » Li-ion diffusion in active materials and Li-ion depletion in the electrolyte phase. Based on those findings, possible approaches were derived to surmount the limiting factors. Finally, the improvement of the energy–power relationship in an 18,650 cell was used to demonstrate how to optimize the thick electrode parameters in cell engineering.« less
NASA Astrophysics Data System (ADS)
Hagino, K.; Balantekin, A. B.; Lwin, N. W.; Thein, Ei Shwe Zin
2018-03-01
The hindrance phenomenon of heavy-ion fusion cross sections at deep subbarrier energies often accompanies a maximum of an astrophysical S factor at a threshold energy for fusion hindrance. We argue that this phenomenon can naturally be explained when the fusion excitation function is fitted with two potentials, with a larger (smaller) logarithmic slope at energies lower (higher) than the threshold energy. This analysis clearly suggests that the astrophysical S factor provides a convenient tool to analyze the deep subbarrier hindrance phenomenon, even though the S factor may have a strong energy dependence for heavy-ion systems unlike that for astrophysical reactions.