Light Ions Research Articles

Relativistic and Heavy Ion Effects on Single‐ and Multi‐Soliton Structures of Ion‐Acoustic Waves

ABSTRACTThe fundamental characteristics of ion‐acoustic waves (IAWs) due to the relativistic effects are investigated in a collisionless unmagnetized plasma system consisting of relativistic positively charged inertial heavy ions, kappa‐distributed electrons, and Maxwellian light ions. The reductive perturbation method (RPM) is used to derive the nonlinear evolution equation like the Korteweg‐de Vries (KdV) equation. The production of single‐, double‐, and triple‐IAW solitons (IAWSs) is also investigated. It is found that for the effects of concerned parameters only rarefactive (IAWSs) are produced. The results obtained in this study are useful not only to understand the space plasma phenomena such as plasma sheet boundary layer of earth's magnetosphere, laser‐plasma interaction, but also to validate the laboratory experiments.

Beam Dynamics in the Heavy Ion Injector LU2 for the Synchrotron Research Complex (SRC)

The project of the complex for studying ionizing radiation exposure from outer space based on the synchrotron accelerator of protons and various types of ions up to 209Bi is being developed at the Russian Federal Nuclear Center - All-Russian Research Institute ofExperimental Physics (FSUE RFNC - VNIIEF). The accelerator includes two injection complexes (one of which is the source of protons and light ions, the second - heavy ions), the booster accelerator and the main synchrotron. The pulsed type heavy ions linac is being developed at the NRC “Kurchatov Institute” - KCTEF (Kurchatov Complex for Theoretical and Experimental Physics). The ions with mass-to-charge ratio 4÷8 with current of 10 mA will be accelerated up to 4 MeV/u. The linac is proposed, including the RFQ and two DTL sections operating at multiple frequencies. Each DTL section is modular and consists of individually phased H-type resonators (IH-DTLs). Quadrupole lenses located between the resonators for the beam focusing. This DTL structure ensures the accelerator compactness and allows section-by-section configuration and sequential commissioning. 6D beam matching between all sections of the linac is carried out. The results ofbeam dynamics simulation in linear accelerator are presented.

Analytical Theory of Reflection of Hydrogen Isotopes of Thermonuclear Energies from Construction Materials

A theoretical description of reflection of hydrogen isotopes from a solid body based on data available in modern literature on the cross sections for elastic and inelastic scattering of ions is presented. The results of the analytical calculation are compared with the results of computer simulation and experimental data. The interaction of hydrogen isotopes with energies from 300 eV to 25 keV with materials in a wide range of atomic numbers, namely Be, C, Ti, Ni, W, Au, is considered. A critical review of existing analytical models of multiple scattering of light ions in solids is performed.

Tracking performances of the ePIC detector at the Electron-Ion Collider

The ePIC (electron–Proton/Ion Collider) experiment is a future facility at the Electron-Ion Collider (EIC) complex, located at the Brookhaven National Laboratory, USA. It will use ∼70% longitudinally polarized beam of electrons, protons, and light ions to study their collisions to understand the properties of the quarks, gluons, and the strong force responsible for the formation of the nucleus. The layout of the central detector of the ePIC experiment is not symmetric along the beams axis consisting of barrel, forward, and backward detectors to achieve a wide pseudorapidity (|η|< 3.5) coverage. There are further far-forward and far-backward tracking detectors to measure the luminosity and reconstruct the particles and fragments for the study of the exclusive deep-inelastic scattering (DIS) processes. The experiment has a challenging environment due to the presence of the background radiations (synchrotron radiation, beam-gas interactions, minimum-bias events, etc.) which will produce additional background hits on the tracker. The synchrotron radiation is suppressed to some extent by coating the beampipe with a 5μm gold layer. The experiment uses state-of-the-art bent wafer-scale silicon monolithic active pixel sensors (MAPS) with a ∼5μs acquisition window, micro-pattern gas detector (MPGD) with a good time resolution (∼20–30ns), and time-of-flight detectors based on AC-LGAD sensors (time resolution ∼30ps). The timing information of each detector will play a crucial role in track finding and rejecting the background hits utilizing the 4-dimensional tracking (space, time) to ensure the excellent performance of the experiment. The article presents the expected tracking performance of the ePIC detector using the modular ePIC software stack for simulation, reconstruction, and analysis. The Geant4 toolkit is employed for full detector simulations, alongside DD4hep (Detector Description for High Energy Physics) for geometry definition and exchange. The reconstruction incorporates the JANA2 framework, in addition to the tracking and vertexing algorithms inherited from A Common Tracking Software (ACTS).

Swift heavy ion irradiation-induced enhancement of spin–orbit torque efficiency in Pt/Co/Ta trilayers

Increasing the efficiency of spin–orbit torque (SOT) is of great interest in applications for magnetic random access memory and logic devices due to decreased energy consumption. Here, we present that the SOT efficiency of Pt/Co/Ta films with perpendicular magnetic anisotropy can be improved by swift high-energy heavy Fe11+ ion irradiation, which is an effective method to alter crystallinity, interface roughness, and defects in ferromagnet/heavy metal heterostructures. Specifically, the Pt/Co/Ta films show an optimal SOT efficiency at ion fluence around 1.0 × 1013 ions/cm2 with the largest spin Hall angles reaching 0.59, which is the largest improvement of spin Hall angle by ion irradiation compared to previous studies using light ions. We demonstrate that the increase in SOT efficiency arises from structural changes in the Pt layer due to ion irradiation-induced damage effects at proper fluence, while the decrease in SOT efficiency is mainly attributed to the restoration of Pt crystallinity induced by beam-heating effects at high fluence. This work demonstrates that an appropriate ion irradiation process could improve the SOT efficiency and the spin Hall angle, thereby providing a way to develop future SOT-based spintronic devices.

Synergistic effects of hydrogen and helium on dislocation loop rafting phenomena and hardening behavior of chromium

Dislocation loop rafts (DLRs), which are ordered arrangements of dislocation loops, are commonly observed in metals under neutron and heavy ion irradiation, yet they have seldom been observed under light ion irradiation. In this study, we reported the formation of DLRs under the synergistic effects of hydrogen and helium in a pure chromium (Cr) coating. Irradiation at room temperature with either single H+or He+ did not result in the formation of DLRs within the Cr coating. Approximately half of the dislocation loops induced by single H+ and He+ irradiation were of the a0〈100〉 type. Nevertheless, DLRs appeared under the combinational irradiation of H+and subsequent He+. The rafts were densely distributed, with lengths of up to 150 nm, and were exclusively composed of 1/2 a0 [11–1] variants along the 〈110〉 crystallographic direction. The emergence of DLRs, affected by the synergistic effect of H and He, results in an enhancement of irradiation hardening.

Simulation of ion beam sputtering with OKSANA and SRIM: A comparative study

The energy distributions and average energies of sputtered particles are calculated using simulation codes OKSANA and SRIM-2013. Most simulations refer to an amorphous Ni target bombarded by normally incident Ar ions of keV energies. Sputtering of Si, Ti, V and Nb targets is also considered. It is shown that SRIM can strongly overestimate the contribution of fast ejected atoms, especially for targets irradiated with lighter ions. The effect is amplified by using the surface binding energies found to fit the measured sputter yields. It is concluded that the enhanced ejection of fast particles is associated with sputtering due to backscattered ions. The role of the first collision of an incident ion with a target atom is particularly noted. A comparison of the OKSANA calculated results with the data of other codes (TRIM.SP, ACAT) and experimental data showed their reasonable agreement.

Heterocyclic Hemipiperazines: Multistimuli-Responsive Switches and Sensors for Zinc or Cadmium Ions.

Advance in the design of molecular photoswitches - adapters that convert light into changes at molecular level - opens up exciting possibilities in preparing smart polymers, drugs photoactivated inside humans, or light-fueled nanomachines that might in the future operate in our bloodstream. Hemipiperazines are recently reported biocompatible molecular photoswitches based on cyclic dipeptides. Here we report a multistimuli-responsive hemipiperazine-based switch that reacts on light, solvents, acidity, or metal ions. Its photoequilibration is controlled by the intramolecular hydrogen bonding pattern. The compound can be used as a mid-nanomolar photoswitchable fluorescent sensor for zinc and cadmium ions, applicable to monitor environmental pollution in real time.

Impact of Ion Pressure Anisotropy in Collisional Quantum Magneto-Plasma with Heavy and Light Ions

We have examined collisional degenerate plasma composed of charged state of heavy positive ion and light positive as well as negative ion. Employing the reductive perturbation method, we derived the damped Korteweg-de Vries-Burgers (dKdV-B) equation and by using its standard solution we analyze the characteristics of the solitary-shock profile under varying parameters. Furthermore, with the application of planar dynamical systems bifurcation theory, the phase portraits have been analyzed. This dynamical system analysis allowed us to extract important information on the stability of these structures as represented by the dKdV-B equation.

Atmospheric ion escape and solar wind deposition as a function of planetary radius

ABSTRACT We explore the ability of an unmagnetized planet to retain an atmosphere as a function of its radius. We use a particle-in-cell hybrid code to simulate the global plasma interaction of unmagnetized terrestrial planets at 1 au under average solar wind conditions. We vary the radius of the planet $(R_\mathrm{ p})$ from Mars-sized ($3390 \ \mathrm{km}$) to super-Earth-sized ($9390 \ \mathrm{km}$). We inject hydrogen and oxygen ion outflows from the ionosphere and quantify how the ion escape, recirculation, solar wind deposition, and net atmospheric mass flux vary as a function of planetary radius. We find that as the radius and the corresponding ionospheric outflow rate are varied, the fraction of outflowing $\mathrm{ H^+}$ that escapes remains at $15.5\pm 1.0{{\ \rm per\, cent}}$, while the rest recirculates back towards the planet. The fraction of produced $\mathrm{ O^+}$ that escapes from a Mars-sized planet is $27\pm 1{{\ \rm per\, cent}}$, and decreases to $7\pm 1{{\ \rm per\, cent}}$ for super-Earth, suggesting that smaller planets are less able to retain heavy ions. We find, however, that larger planets have lower solar wind deposition fractions because their bow shocks are at greater distances from the surface of the planet. The ionospheric outflow rate at which mass deposition is equal to mass escape is found to be proportional to $R_\mathrm{ p}^2$. Lastly, we propose that the bulk gyration of the solar wind at the induced magnetosphere can lead to differential escape trajectories of light and heavy ions.

Comparative study of magnetic field effect on fast plasma flow of heavy and light species investigated by spectroscopic measurement

To understand the effects of magnetic fields on the propagating plasma flows of heavy and light ion species, a laboratory-scale experiment was conducted using a pulsed-power discharge. The plasma drift velocity and electron temperature were estimated by time-of-flight and line-pair methods, respectively, using spectroscopic measurements. Ion current waveforms were measured using an ion collector. When a magnetic field was applied, the plasma drift velocity decreased and the electron temperature increased in both heavy and light plasmas. The magnetic Reynolds number, pressure balance between the plasma and magnetic field, and ion current waveforms show that heavy plasma has a high possibility of deforming the magnetic field and generating accelerated ions through interaction with the magnetic field.

Impurity transport in PISCES-RF*

Abstract Linear plasma devices (LPD) utilizing a helicon plasma source, a high density light ion source, can generate impurities due to progressive erosion of the radio frequency (RF) transmission window caused by rectified sheath voltage. These source-born impurities can entrain and be transported by the plasma toward a target, affecting plasma-material interaction studies. Earlier work on material testing in Prototype-Materials Plasma Exposure eXperiment at ORNL revealed significant source impurity deposition on downstream targets. However, using a similar RF source, no target impurity deposition is observed in Plasma Interaction Surface Component Experimental Station (PISCES)-RF despite evidence of RF window erosion in the source region, thereby motivating the present work. Experimentally, using various magnetic field configurations upstream of the PISCES-RF plasma source and seeding titanium (Ti) impurities at various axial locations, impurity transport and deposition along the machine axis were investigated. It was found that Ti deposition was localized to the side of the plasma source where the Ti impurity was seeded. In contrast, aluminum (Al) deposition, originating from the sputtering of the helicon window, occurred predominantly upstream of the plasma source, suggesting an asymmetry in the axial transport of eroded RF window material. These observations suggest a stagnation of the parallel plasma flow immediately downstream of the plasma source, with impurity ions remaining unmagnetized near the source upstream. Al deposition in magnetic field-free regions in PISCES-RF indicates that sputtered Al impurities likely remained neutral due to their large ionization mean-free path under PISCES-RF conditions. Plasma modeling and simulation supported this, indicating that Al-neutrals transport toward the helicon source upstream for low electron density cases. It was found that the Larmor radius of the Al ions was greater than the plasma radius towards the source upstream and remained weakly magnetized in PISCES-RF, meaning that plasma source-born impurities are not efficiently entrained in the plasma flow. These findings provide critical insights into impurity transport in helicon plasma-based LPDs.

(Invited) Drug Delivery System of Photoresponsive Donor-Acceptor-Linked Molecules to Mouse Retina

Neurotransmission is mediated by electrical pulses that are generated by coordinated activation and deactivation of ion channels in the plasma membrane of neuronal cells. The ion channels control the plasma membrane potential (V m) by influx/efflux of ions. In our retina, the V m is controlled by light and photo-excitable ion channels in photoreceptor cells and voltage-dependent ion channels in neuronal ganglion cells, which transmit visual signal to the brain. In contrast, patients with visual impairment and blindness, e.g., with age-related macular degeneration, lose response to light due to irreversible elimination of photoreceptor cells. Therefore, restoring vision is potentially possible by direct photoexcitation of neuronal ganglion cells with photoresponsive V m-controlling molecules. As one of such molecules, we have focused on donor-acceptor-linked molecules (D–A molecules) capable of photoinduced intramolecular long-lived charge separation [1–4]. In this symposium, I will introduce my recent research mainly on drug delivery system of D–A molecules to the retina in mice [5].REFERENCES[1] Imahori, H. et al., J. Am. Chem. Soc. 2001, 123, 2607–2617.[2] Numata, T. et al., J. Am. Chem. Soc. 2012, 134, 6092–6095.[3] Takano, Y. et al., Chem. Sci. 2016, 7, 3331–3337.[4] Numata, T. et al., Cell. Physiol. Biochem. 2020, 54, 899–916.[5] Fukuda, R. et al., Adv. Therap. 2023, 6, 2300186.

Study of the out-of-field dose from an accelerator-based neutron source for boron neutron capture therapy

One important issue in Boron Neutron Capture Therapy is the delivered dose to the tissues outside the tumor. An international standard for light ion beam systems sets two recommended limits for out-of-field dose based on distance from the field edge: maximum absorbed dose from all radiation types shall not exceed 0.5 % of the maximum dose at distances 15 cm to 50 cm from the field edge. At distances >50 cm from the field edge, the maximum absorbed dose shall not exceed 0.1 %. This paper is a continuation of our previous works focused on the design of an accelerator-based neutron source for BNCT. We already designed a novel Beam Shape Assembly which meets the IAEA criteria for BNCT treatments. Using this BSA, in the present work, we characterize by Monte Carlo simulations the dose outside the neutron field. The out-of-field dose has been assessed via estimates using the ambient and equivalent dose. Also the boron uptake in healthy tissues has been analyzed for the equivalent dose computation. It is concluded that our design for a future accelerator-based source for BNCT meets reasonably well the criteria defined from other forms of radiotherapy on both equivalent and effective dose outside the field.

CLIEMiT (Correlative Light Electron and Ion Microscopy in Tissue)

CLIEMiT (Correlative Light Electron and Ion Microscopy in Tissue)

Complex shock structure in multi-species dusty plasma with nonextensive electrons and two-temperature nonthermal ions

A theoretical investigation has been made to explore the behavior of nonplanar (cylindrical and spherical) electrostatic shock waves in a dusty plasma system that consists of arbitarily charged dust particles, negatively charged heavy ions following Cairn’s distribution, positively charged ions with two different temperatures, and nonextensive electrons. The reductive perturbation technique is used to derive a modified Burgers equation analytically. Analytical analysis shows that the characteristics of the nonplanar shock waves, including their polarity, amplitude, width, and phase speed, undergo significant alterations due to factors such as the charges on dust particles, the number density of particles, the temperatures of heavy and light ions, nonextensive electron behavior, and dust kinematic viscosity. Furthermore, this study found shock structures with either a positive or negative potential, depending on the critical value of the proportion of ions to the density of dust particles. The findings maybe useful in understanding the characteristics of shock waves both in space plasma environments and laboratory plasmas.

Calculation of the Component Composition of the Surface Layers of Titanium Carbide Sputtered with Light Ions

Calculation of the Component Composition of the Surface Layers of Titanium Carbide Sputtered with Light Ions

Radial and Vertical Structures of Plasma Disk in Jupiter's Middle Magnetosphere

AbstractThe Juno mission flew through the plasma disk near the equator in Jupiter's magnetosphere frequently. We identify 274 plasma disk crossings of Juno between 10 and 40 RJ from PJ5 to PJ44. Using a forward modeling method that combines the JADE‐I time‐of‐flight and SPECIES data sets, we perform a survey of ion properties in the plasma disk. Ions are heated from 1.5 to 6 keV between 15 and 30 RJ. Density and temperature are locally anti‐correlated. Assumed to be related to centrifugal instabilities, cold, dense plasma are commonly observed near midnight. Plasma corotates around Jupiter and the rigid corotation breaks down outside 15–20 RJ. The plasma bulk velocity increases from the post‐dusk sector to the pre‐dawn sector featuring injection flows in the pre‐dawn sector, which is consistent with the Vasyliunas cycle. Strong outflows (&gt;100 km/s) are commonly observed outside 20 RJ and the average radial velocity increases with radial distance. The ion abundance changes between 10 and 18 RJ and that might indicate plasma sources and/or sinks near Europa and Ganymede. The vertical distribution of ions is controlled by the balance between centrifugal, pressure gradient, and ambipolar electric field forces. An example near the M‐shell of 13.5 shows that average plasma temperature increases by a factor of 10 from the disk center to edge, because cold ions are more confined near the equator. Lighter ions with higher charge states have more mobility along the field line and have larger scale heights. The observations are compared with multi‐species diffusive equilibrium model.

Secondary neutrons in proton and light ion beam therapy: a review of current status, needs and potential solutions

The advantages of proton and light ion beam therapy compared to conventional photon radiation therapy are well-known, mainly thanks to the characteristic depth dose distribution of ions and their radio-biological effectiveness. Nevertheless, the use of ions implies different nuclear reactions that generate secondary particles, with neutrons among them. These secondary neutrons can travel far away from the treatment volume, their measurement is a challenging complex task, and their biological effects are particularly high for neutrons with energies in the MeV range. In this review, a comprehensive description of secondary neutron dosimetry in proton and light ion beam therapy is given. Many studies have been conducted on the quantification of the secondary neutron dose, most of them have been performed for proton beams, whereas for other ions like carbon, the available information is scarce. The main measurement campaigns are summarised, focusing on the type of detectors used. In line with the detectors’ advantages and limitations, measurements performed inside and outside anthropomorphic phantoms are considered. The role of Monte Carlo radiation transport simulations is discussed since many experimental detection techniques need additional simulations to provide dose estimates. A focus on the current challenges for the measurements of neutrons with energies above 20 MeV is given, as this is one of the main components of secondary neutrons produced by therapeutic ion beams. Finally, the potential clinical relevance of the available and needed secondary neutron dose data is discussed, in terms of its impact on the treatment of patients. For this, the relative biological effectiveness of neutrons and the potential risk of cancer induction re-incidence or secondary cancer due to secondary neutron doses play a key role.

Online separation of critical rare earth elements from end-of-life permanent magnets using micro polymer inclusion beads (µPIBs)

A column filled with micro polymer inclusion beads (µPIBs) was developed and investigated for the first time. The µPIBs were composed of 60 wt% di-(2-ethyl-hexyl) phosphoric acid (D2EHPA) and 40 wt% poly(vinyl chloride) (PVC) and the column was used for the separation of ions of rare earth elements (REEs) from synthetic solutions and the digest of end-of-life (EOL) rare earth permanent magnets (REPMs). This µPIB packed column was successfully applied to separating La3+ from Gd3+, as representatives of the light and middle REEs, previously achieved by us using a polymer inclusion membrane (PIM) containing the same chemical components as the µPIBs used in this study. The results obtained demonstrated the feasibility of the µPIBs packed in a column for light and middle REE ion separation similarly to their PIM counterpart. The separation potential of the µPIB packed column was further demonstrated by the selective recovery of Nd3+ and Dy3+ from an EOL REPM digest in 2 M sulfuric acid which also contained Fe3+, Co2+, and Ni2+. Nd3+ and Dy3+ could be selectively extracted from the diluted to 0.03 M sulfuric acid digest after the addition of ascorbic acid which reduced Fe3+ to Fe2+. Nd3+ and Dy3+ were separated via selective back-extraction from the µPIB-column using 0.3 and 2 M sulfuric acid receiving solutions, respectively. Thermogravimetric analysis of the µPIBs, before and after application in the µPIB-column, indicated negligible D2EHPA loss after six processing cycles. Thus, these results demonstrated the strong potential of the proposed µPIB-column method for the sustainable recovery of REEs from electronic waste such as REPMs.