Low-charge Ions Research Articles

Ion source developments to supply mono & multi charged ion beams to the new NHa C400 hadrontherapy system.

Normandy Hadrontherapy (NHa) is developing, in collaboration with Ion Beam Applications (IBA), a full hadrontherapy treatment solution based on a new multiparticle cyclotron. 12C6+ and 4He2+ ions will be accelerated up to 400 MeV/u and (H2)+ up to 260 MeV/u. Three different ion sources will be carried out for each accelerated particle: the mono-charged ion source (H2)+ and low charged ion source He2+ are provided by the Polygon Physics (PP) company. The carbon ion source is under development at NHa in collaboration with IBA and PP. The (H2)+ ion source is an industrial Tubular ECR Source (TES) fitted for the needs of the NHa C400 cyclotron (30 µA of (H2)+). The He2+ ion source is a classic 10 GHz ECR type with a new concept because the complete source is set inside a vacuum chamber and it runs under 10−6 mbar of gas residual pressure. The 12C6+ ion source is also an ECR type ion source operating at 14.5 GHz frequency, its design is under progress to produce a beam providing stability and reproducibility levels compatible with clinical use. The article will present the External Injection System of the NHa C400 cyclotron hence it will focus on the experimental results obtained with the (H2)+ ion source and preliminary outputs from the He2+ ECRIS. A presentation of the multicharged ECRIS design dedicated to the 12C6+ production will be done.

Generation of plasma from multiple targets by laser ion source for TIARA ion implanter

We investigated a laser ion source for use as an ion source for the ion implanter in Takasaki Ion Accelerators for Advanced Radiation Application to increase the number of ion species that can be produced and to enable rapid switching of ion species. Herein, we analyzed the charge state distribution of ions in a laser plasma generated through irradiation of graphite, titanium, copper, and tantalum targets with 30 mJ Nd:YAG laser to determine the particle number of low-charge ions per pulse at 1.1 m from the target. The particle number of singly charged ions could be increased by adjusting the laser power density. For carbon, titanium, and tantalum, the particle numbers were in the order of 1010 ions per pulse, whereas for copper, the particle numbers were in the order of 109, lower than for other target materials.

XPS and NEXAFS Characterization of Mg/Zn and Mn Codoped Bismuth Tantalate Pyrochlores

Two series of the bismuth tantalate pyrochlore samples, codoped with Mg,Mn and Zn,Mn, were synthesized via solid-phase reaction. It was established that the Bi2Mg(Zn)xMn1−xTa2O9.5−Δ (x = 0.3; 0.5; 0.7) samples contain the main phase of cubic pyrochlore (sp. gr. Fd-3m) and an admixture of triclinic BiTaO4 (sp. gr. P-1). In both sets, the amount of BiTaO4 is proportional to the amount of manganese doping, however, zinc-containing samples have a higher level of impurities than magnesium-containing ones. The unit cell parameter of the Zn,Mn codoped bismuth tantalate phase increases with an increasing content of zinc ions in the samples from 10.4895(5) (x = 0.3) to 10.5325(5) Å (x = 0.7). The unit cell parameter of Mg,Mn codoped bismuth tantalate pyrochlores increases uniformly with an increasing index x(Mg) from 10.4970(8) at x = 0.3 to 10.5248(8) Å at x = 0.7, according to the Vegard rule. The NEXAFS and XPS data showed that the ions were found to have oxidation states of Bi(+3), Ta(+5), Zn(+2) and Mg(+2). In the Ta 4f XPS spectrum of both series of samples, a low energy shift of the absorption band characteristic of tantalum ions with an effective charge of (+5-δ) was observed. The XPS spectra of Bi4f7/2 and Bi4f5/2 also show a shift of bands towards lower energies which is attributed to the presence of some low-charge ions of transition elements in the bismuth position. The NEXAFS spectroscopy data showed that manganese ions in both series of samples have predominantly 2+ and 3+ oxidation states. XPS data indicate that in zinc-containing preparations the proportion of oxidized manganese ions is higher than in magnesium-containing ones.

Uniformity optimization of ion beam sputtering coating equipment based on strong current ion source

The widespread application of ion beam sputtering coating, especially in optical devices, requires the improvement of beam current intensity and uniformity of large-area uniform coatings. The advent of high current Penning sources offers a potential solution. This study introduces an automated optimization simulation method based on a three-electrode extraction system to investigate its influence on ion beam quality and uniformity. Focusing on high current intensity and uniformity, our simulation explores the effects of plasma electrode, inhibition electrode, and extraction electrode angles and distances on ion beam performance. Evaluation metrics include average beam intensity density, average energy of a single particle, and reciprocal variance of each macro particle position, which are achieved through normalization functions, allowing comprehensive comparison of simulation results. To assess coating efficiency, we estimate sputtering yield and depth. The study identifies patterns among electrodes and emphasizes the influence of different ion ratios on beam extraction. The results indicate that optimizing the angle of the plasma electrode and the distance of the suppressed electrode yields a highly uniform ion beam for low charge ions. However, for highly charged ions, similar optimization will reduce the current strength, so compensation needs to be achieved through electrode shape optimization. This research provides a model for systematically optimizing the three-electrode extraction system, guiding researchers in achieving optimal solutions based on ion source characteristics and application requirements. Additionally, we introduce a method of estimating the sputtering depth of mixed ion beams. This study provides valuable insights for advancing ion beam sputtering coating technology and reference for making the decision on design and application of ion source.

The role of charge-exchange processes in probing hydrogen plasma with a heavy ion beam

Charge-changing processes of low-charged ions, used in hydrogen plasma probing by the heavy ion beam probe method, are considered. Along with the ionization of beam ions by plasma electrons and protons, the charge-exchange processes of ions on H atoms and protons are also studied. It is shown that charge exchange of beam ions on plasma protons and H atoms, which is rarely taken into account, plays an important role in beam–plasma interaction. New data on the cross sections and rates of ionization and charge-exchange processes are presented for Tl+ and Tl2+ ions, which are frequently used for plasma diagnostics. Calculations are performed for hydrogen plasma temperatures Te = 1 eV–10 keV and densities Ne = 1012–1014 cm−3 at relatively low and high ion-beam velocities vb = 0.2 and 1.0 a.u., respectively. Special attention is paid to the determination of the electron temperatures at which the charge-exchange processes on H atoms and protons are important. Multiple ionization of beam ions by plasma electrons and protons is briefly discussed.

Tailoring of ZnFe2O4-ZrO2-based nanoarchitectures catalyst for supercapacitor electrode material and methanol oxidation reaction

Herein, a simple hydrothermal approach was employed to synthesize a homogeneous and compact ZnFe2O4 nanoparticles on the surface of ZrO2 (ZnFe2O4-ZrO2), and it was utilized as a supporting-material for Pt nanoparticles. The fabricated ZnFe2O4-ZrO2 and ZnFe2O4-ZrO2/Pt nanoarchitectures were employed as an electrode material for the supercapacitor cells, and an electrocatalyst for the methanol oxidation reaction, respectively. The Pt nanoparticles were electrochemically deposited on the ZnFe2O4-ZrO2 support. The electrochemical characterizations illustrated that ZnFe2O4-ZrO2 supported Pt was of a peak current density of 104.74 mA/cm2, which was 1.73 more than the peak current density of Pt without the use of nanocomposite support and strong cycling stability of 110 percent after 150 cycles for the methanol oxidation reaction. As a supercapacitor electrode, ZnFe2O4-ZrO2 offered a high specific capacitance of 193.76F/g at a current density of 1.0 A/g, an appropriate rate efficiency (102.4 F/g at current density of 8 A/g), and strong cycling stability of 93 % after 250 galvanostatic charge–discharge revealing the high cycle stability of the nanocomposite. The superb electrochemical behavior of the ZnFe2O4-ZrO2 electrode was ascribed to the low internal charge resistance and ion diffusion resistance. The more ion/electron pathways of diffusion and a suitable contact area with the electrolyte, and the strong synergistic interaction between the components conferred exceptional conductivity and structural durability on the electrode. The results paved the new avenues for nanoengineering of up-and-coming metal-based nanoarchitectures to be utilized in energy storage and conversion systems.

Prediction of charge-changing cross sections of low-charged 88Sr, 138Ba and 142Nd ions in a He-gas target at collision energies 50 eV/u–10 GeV/u

Electron-loss (EL) and electron-capture (EC) cross sections of neutral and low-charged heavy Srq+, Baq+ and Ndq+ ions with charges q = 0, 1 and 2 in collisions with He atoms are predicted in the energy range E = 50 eV/u–10 GeV/u. Experimental data on EL and EC cross sections of these particles colliding with He atoms are practically absent. At relatively low energies E = 8–30 keV, EL cross sections σ12 of Sr1+, Ba1+ and Nd1+ ions are predicted from new experimental equilibrium charge-state fractions F1 and F2 and calculated EC cross sections. Predicted value for Ba1+ ions, σ12=6.8⋅10−18cm2, is in a good agreement with the one available experimental point σ12exp=5.7⋅10−18cm2 at E = 20 keV (Fedorenko, 1954). Calculations of EL and EC cross sections are performed by available computer codes shortly described in the paper. Theoretically estimated neutral-atom fractions F0 are found much smaller than the measured F1, F2, and F3 charge-state fractions.

Is conductivity measurement or inductively coupled plasma-atomic emission spectrometry reliable to define rejection of different ions?

Rejection of single salts or ions is a basic and crucial characteristic of nanofiltration (NF) membranes. The simple and most pursued method to quantify the salt concentration has been via conductivity measurement. Pitfalls exist when ions hydrolysis or feed water contains monovalent ions. This could be explained in two possible scenarios: (1) easily hydrolyzed single salts form low charged ions and reduce feed pH, resulting in increased permeate conductivity and low nominal rejection; (2) for membranes with high multivalent ion rejections (>99%) or the concentration of target ions in feed is low, conductivity measurement results in low rejection due to the passage of monovalent ions if deionized water is used for the feed solution. A correction formula by subtracting the concentration of monovalent ions in water to obtain an accurate rejection value is proposed. This work provides an accurate, simple and robust evaluation of rejection for NF membranes, which promotes fair comparison of performance in literature, reliable analysis of separation mechanisms as well as a precise determination of product purity.

Novel Isobaric Tagging Reagent Enabled Multiplex Quantitative Glycoproteomics via Electron-Transfer/Higher-Energy Collisional Dissociation (EThcD) Mass Spectrometry.

Protein glycosylation, covalent attachment of carbohydrates to polypeptide chains, is a highly important post-translational modification involved in many essential physiological processes. Comprehensive site-specific and quantitative analysis is crucial for revealing the diverse functions and dynamics of glycosylation. To characterize intact glycopeptides, mass spectrometry (MS)-based glycoproteomics employs versatile fragmentation methods, among which electron-transfer/higher-energy collision dissociation (EThcD) has gained great popularity. However, the inherent limitation of EThcD in fragmenting low-charge ions has prevented its widespread applications. Furthermore, there is a need to develop a high-throughput strategy for comparative glycoproteomics with a large cohort of samples. Herein, we developed isobaric N,N-dimethyl leucine-derivatized ethylenediamine (DiLeuEN) tags to increase the charge states of glycopeptides, thereby improving the fragmentation efficiency and allowing for in-depth intact glycopeptide analysis, especially for sialoglycopeptides. Moreover, the unique reporter ions of DiLeuEN-labeled glycopeptides generated in tandem MS spectra enable relative quantification of up to four samples in a single analysis, which represents a new high-throughput method for quantitative glycoproteomics.

Numerical study of the effect of aft-loaded magnetic field on multiple ionizations in Hall thruster

It is assumed that the shift of a strong magnetic field region with a positive gradient from exit plane to outside, namely the transit from a normal loaded magnetic field to an aft-loaded one, enhances the multiple ionization process in the magnetically shielded Hall thruster. To confirm this conjecture, a comparative study is carried out numerically with a particle-in-cell method. The simulation results prove that compared with the normal loaded magnetic field, the application of aft-loaded magnetic field enhances the multiple ionization process. This study further analyzes the ionization characteristics of the transition from low-charged ions to high-charged ions under two magnetic field conditions and the influence of the magnetic strength of aft-loaded magnetic field on the multiple ionization characteristics. The study described herein is useful for understanding the discharge characteristics of Hall thruster with an aft-loaded magnetic field.

Vanadium-doped Co0.85Se nanowire arrays with high areal capacitance for hybrid supercapacitor electrodes

The continuous exploration of advanced electrode materials is noteworthy to reform next-generation high-performance energy storage technology toward a green future. Benefiting from their abundant redox centers and electrochemically active sites, transition metal selenides (TMSs) have emerged as promising electrode materials for supercapacitors, which present massive potential in bridging a gap between the high power density and enhanced energy density. In this paper, we provide a two-step approach for constructing vanadium-doped Co0.85Se (V-doped Co0.85Se) nanowires on nickel foam that have outstanding electrochemical performance. In the three-electrode system, the areal specific capacity of the V-doped Co0.85Se was found as high as 1.28 mAh cm−2 (127.78 mAh g−1) at 5 mA cm −2, which is 1.97 times of that of the Co0.85Se electrode. The assembled quasi-solid-state hybrid supercapacitor also exhibits impressive electrochemical performance, possessing an energy density of 5.30 mWh cm−3 at a power density of 51.15 mW cm−3, and an excellent cycling stability (with capacitance retention of 84.2% after 5000 cycles). The enhanced electrochemical performance of the V-doped Co0.85Se is caused by a unique nanowire-like morphology with high specific surface area, and low charge transfer resistance and ion diffusion resistance. This work provides a feasible strategy for combining metallic element vanadium with selenide electrodes.

CERN hadron sources: status and innovation overview

The CERN accelerator complex is served by several different types of hadron sources, producing both high- and low-intensity negative H- beams, highly charged positive stable ions, but also transforming low-charge radioactive ions to higher charges before post-acceleration. Apart from the operational sources, research and development is carried out at dedicated test stands for H- production and pre-acceleration, ECRIS oven experiments and general EBIS development. In this paper, we will report on the performance and the latest development related to the sources. Efforts to enhance the theoretical understanding of the source physics will be briefly reviewed.

Giant dipole plasmon resonance in fluorene (C13H10) molecules

We report the observation of the giant dipole plasmon resonance in the fluorene molecule $({\mathrm{C}}_{13}{\mathrm{H}}_{10})$, a polycyclic aromatic hydrocarbon, upon collisions with H-like silicon ions. An idea of using highly charged ions to create a large perturbation strength is exploited to observe the plasmon state effectively in the electron double-differential distribution. The signature of plasmon excitation is observed directly as a characteristic broad peak in the electron double-differential spectrum. Such an excited state could not be observed for the same molecule when the low charged ions having lower perturbation were used. This is explained by a model based on dipole approximation and linear response theory for the giant plasmon resonance. The angular distribution of these electrons is modeled using the photoelectron angular distribution for an oscillating dipole superimposed with the postcollision interaction due to the long-range Coulomb interaction between the plasmon electrons and the receding projectile ions.

Gas-phase heme structure of the singly charged cytochrome c anion produced by IR-laser ablation of a droplet beam

Photoelectron detachment yield (PDY) spectroscopy is an effective tool for elucidating gas phase protein structures compared with other spectroscopies in aqueous solutions. In general, investigations of low-charged ions are necessary to elucidate the intrinsic properties of protein because excess charge perturbs the electronic state of the protein. In this study, we measured PDY spectrum of the most low-charged cytochrome c (cyt c) anion, [cyt c]- by IR-laser ablation of a droplet beam. This result shows a spectral blueshift from the absorption peak of aqueous cyt c and the PDY peak of the [cyt c]6- ion reported in the previous study.

Near L-edge Single and Multiple Photoionization of Doubly Charged Iron Ions

Abstract Using the photon–ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe2+ ions in the energy range of 690–920 eV. This range contains thresholds and resonances associated with ionization and excitation of 2p and 2s electrons. Calculations were performed to simulate the total absorption spectra. The theoretical results show very good agreement with the experimental data, if overall energy shifts of up to 2.5 eV are applied to the calculated resonance positions and assumptions are made about the initial experimental population of the various levels of the Fe2+([Ar]3d 6) ground configuration. Furthermore, we performed extensive calculations of the Auger cascades that result when an electron is removed from the 2p subshell of Fe2+. These computations lead to a better agreement with the measured product-charge-state distributions as compared to earlier work. We conclude that the L-shell absorption features of low-charged iron ions are useful for identifying gas-phase iron in the interstellar medium and for discriminating against the various forms of condensed-phase iron bound to composite interstellar dust grains.

Radiative recombination data for low-charged tungsten ions: IV. W[formula omitted]W[formula omitted

The radiative recombination and photoionization cross sections as well as the radiative recombination rate coefficients and the radiated power loss rate coefficients are presented for the low-charged tungsten ions from W3+ to W13+. The data are essential to diagnostic and modeling the divertor plasmas impurities in the ITER tokamak because tungsten has been resolved to use as a plasma-facing material. Partial cross sections and rates are given for the ground and excited electron states with principal quantum numbers n≤10 and orbital momenta ℓ≤4 in the wide energy range. Relativistic calculations have been performed taking into account all significant multipoles of the radiative field. Electron wave functions have been found by the Dirac–Fock method. The relativistic Maxwell–Jüttner distribution of continuum electrons has been used in calculations of radiative recombination and radiated power loss rates. Photoionization cross sections have been fitted by an analytical expression with five fit parameters. Peculiarities of behavior of the cross sections and rates for low-charged ions as well as ensuing problems of the cross section fitting are considered. The radiative recombination rates are compared with other recent calculations for the low-charged tungsten ions.

Theoretical level energies, radiative lifetimes and transitions in W IX

The atomic states of the W IX (W8+) tungsten ion lying below the W9+ ionisation threshold have been studied theoretically, employing the multiconfiguration Dirac–Hartree–Fock method with configuration interaction. The level electronic structures and their energies are presented. The electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) radiative transitions have been computed in order to calculate the radiative lifetimes of given states. Transition wavelengths, energies, and decay rates are also presented for selected high-intensity E1 transitions. The configuration interaction method was applied to estimate electron correlation effects. The aim of the present research was to fill a lack of atomic data for low-charged tungsten ions, which may be useful in low-temperature plasma diagnostics and may form the base for collisional–radiative modelling of spectra for low-charged tungsten ions.

How Spherical Are Gaseous Low Charged Dendrimer Ions: A Molecular Dynamics/Ion Mobility Study?

The globular shape of gaseous ions, resulting from the ionization of large molecules such as polymers and proteins, is a recurring subject that has undergone a renewed interest with the advent of ion mobility spectrometry (IMS), especially in conjunction with theoretical chemistry techniques such as Molecular Dynamics (MD). Globular conformations result from a fine balance between entropy and enthalpy considerations. For multiply charged ions isolated in the gas phase of a mass spectrometer, the Coulombic repulsion between the different charges tends to prevent the ions from adopting a compact, and folded 3D structure. In the present paper, we closely associate data from IMS experiments and MD simulations to unambiguously access the conformations of dendrimer ions in the gas phase with special attention paid to the dendrimer structure, the generation, and the charge state. By doing so, we here combine a set of structural tools able to evaluate the (non)globular shape of ions based on both experimental and theoretical results.

Employing [formula omitted] elastic scattering for determination of K-shell ionization cross section of 58Ni19+ in collisions with hydrogen gas target at 95 MeV/u

We present a new experimental method for measuring inner-shell ionization cross sections of low-charged ions colliding with hydrogen gas target in a storage ring. The method is based on a calibration by the well-known differential cross sections of proton elastic scattering on nuclei. K-shell ionization cross section of 1047(100) barn for the 95 MeV/u 58Ni19+ ions colliding with hydrogen atoms was obtained in this work. Compared to the measured ionization cross section, a good agreement is achieved with the prediction by the Relativistic Ionization CODE Modified program (RICODE-M).

A Laboratory Astrophysics Problem: The Lifetime of Very Long-Lived Levels in Low-Charge Ions

Emission lines of singly charged ions populate many astrophysical spectra. However, the interpretation of the line intensities (usually line ratios) often depends on the transition rates of the decays of very long-lived low-lying levels. For example, the line ratio of two electric-dipole forbidden transitions in the 3s 2 3p 3 ground configuration of singly ionized sulfur (ion S + , spectrum S II) has been interpreted in terms of a density diagnostic for planetary nebulae, i.e., for densities in the order of 10 4 cm − 3 . The predicted lifetimes of the 2 D 3 / 2 , 5 / 2 o levels are in the order of one hour. Modeling indicates that a 10% uncertainty of the lifetime determination in this case corresponds to a 50% uncertainty of the density diagnostic. The available theoretical lifetime predictions scatter by much more than 10%. Considerations about an experimental approach are presented with the goal of instigating a measurement of the actual level lifetimes.