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The harmonic structure of lower hybrid waves (LHWs) driven by energetic ions can be generated through non‐linear wave‐wave coupling. We investigate the parameter dependence of the excitation and time evolution of this structure, using one‐dimensional electromagnetic particle‐in‐cell (PIC) simulations. Focusing on two parameters, ωpe/Ωe ${\omega }_{pe}/{{\Omega }}_{e}$ (ratio of the electron plasma to electron gyro frequencies) and u⊥/vA<1 ${u}_{\perp }/{v}_{A}< 1$ (ratio of energetic‐ion to Alfvén velocities), we analyze the fluctuation spectra in the wavenumber‐frequency plane and demonstrate that the harmonic structure can be excited across wide parameter ranges of 0.25≤ωpe/Ωe≤4 $0.25\le {\omega }_{pe}/{{\Omega }}_{e}\le 4$ and u⊥/vA<1 ${u}_{\perp }/{v}_{A}< 1$, indicating a weak parameter dependence. However, the excitation region and time evolution of the harmonic structure can be significantly affected by these parameters. We find that conditions of low ωpe/Ωe ${\omega }_{pe}/{{\Omega }}_{e}$ and intermediate u⊥/vA ${u}_{\perp }/{v}_{A}$ are preferable for the excitation and survival of the harmonic structure. Previous observations have reported the harmonic structure of LHWs in the polar region at 4,000 km altitude and in the plasma sheet at XGSM ∼ ${\sim} $ 17 RE ${R}_{\mathrm{E}}$. Nevertheless, this study predicts that the harmonic structure can also be excited in other regions of the magnetosphere where energetic ions are present. Plain Language Summary: The harmonic structure of lower hybrid waves (LHWs) can be generated through non‐linear wave‐wave coupling in association with LHW instabilities driven by energetic ions. To investigate the general condition of the excitation and time evolution of the harmonic structure, we conduct kinetic simulations for many cases focusing on the frequency ratio ωpe/Ωe $\left({\omega }_{pe}/{{\Omega }}_{e}\right)$ and the ratio of energetic‐ion to Alfvén velocities u⊥/vA $\left({u}_{\perp }/{v}_{A}\right)$. We find that the harmonic structure of LHWs can be excited under wide parameter ranges of ωpe/Ωe ${\omega }_{pe}/{{\Omega }}_{e}$ and u⊥/vA ${u}_{\perp }/{v}_{A}$, indicating a weak parameter dependence. However, the excitation region and time evolution can be significantly affected by the two parameters. Our findings can increase the possibility that the harmonic structure of LHWs can be excited in the Earth's magnetosphere. Key Points: The harmonic structure of lower hybrid waves (LHWs) driven by energetic ions can be generated through non‐linear wave‐wave couplingWe investigate the parameter dependence of the harmonic structure, paying attention to the two parameters of ωpe/Ωe ${\omega }_{pe}/{{\Omega }}_{e}$ and u⊥/vA ${u}_{\perp }/{v}_{A}$The harmonic structure can be excited under wide parameter ranges of ωpe/Ωe ${\omega }_{pe}/{{\Omega }}_{e}$ and u⊥/vA ${u}_{\perp }/{v}_{A}$, but its time evolution can depend on ωpe/Ωe ${\omega }_{pe}/{{\Omega }}_{e}$ and u⊥/vA ${u}_{\perp }/{v}_{A}$ [ABSTRACT FROM AUTHOR]

Recent observations on the HL-2A tokamak give new experimental evidence of resonant tearing modes (r-TMs) caused by the redistribution of energetic ions (EIs) due to sawtooth collapses in neutral beam injection plasmas. The $m/n = 2/1$ ( m and n are the poloidal and toroidal mode numbers) r-TMs with frequencies chirping down rapidly are found after strong bursts of fishbone modes and closely followed strong sawtooth collapses. The frequencies of fishbone modes and r-TMs chirp down from 10 to 7 kHz and 5 to 2 kHz rapidly, higher and lower than the 4–6 kHz existing weak resistive TMs. The fishbone modes propagate in ion diamagnetic drift directions in poloidal. In contrast, r-TMs propagate in the electron diamagnetic drift direction, though r-TMs are excited by EIs. It is suggested that counter-passing EIs, which originated from redistribution of EIs due to fishbone modes and combined with sawtooth collapses, excite r-TMs. Simulation results from the M3D-K code reveal that the counter-passing EIs play an important role in the excitation of r-TMs. The results can help broaden understanding of the interaction mechanisms between energetic particles and TMs, and open up a new perspective on the excitation mechanism of r-TMs.

The excitation of modes in the JET tokamak in the sub-cyclotronic range of frequencies (frequencies comprised between the Alfvén frequency and the cyclotron frequency) is for the first time reported. The modes were identified as compressional Alfvén eigenmodes and have characteristics similar to those of the sub-cyclotronic modes observed in other tokamaks, in particular those first reported in the NSTX tokamak. On the other hand, the modes observed in JET present some unique features and were observed to be excited by ion cyclotron resonance heating instead of by the injection of beams (neutral beam injection).

Energy loss per unit length - d E / d x of Li, C and O ions in self-supporting Ag foils is measured by adopting the transmission technique. These measured values are compared with the prediction of the most commonly used theoretical/semiempirical formulations, viz., Benton and Henke, Northcliffe-Schilling, Hubert et al., Diwan et al., ICRU report 73, Paul and Schinner (MSTAR V3.12 code), Grande and Schwietz (CasP 5.2 code), and Ziegler et al. (SRIM-2013.00 code). This comparison aims to check the accuracy of the considered formulations. [ABSTRACT FROM AUTHOR]

Development of low-orbiting constellations stimulated the demand for low-power Hall thrusters, as well as their accompanying low-current hollow cathodes. In this paper, such cathodes were tested on quite low currents to search their self-sustaining limit, and were found to exhibit an ultra-low frequency instability at lower current limit. The instability would grow fast when the cathode current was below 0.3A, and oscillate on 0.1Hz to a few Hz with a visibly blinking plume. At the same time, the emitter temperature was fluctuating with a 15 °C peak-to-peak amplitude. The instability was confirmed to originate from the cathode interior, as a result of depleted plasma heating. Then the thermionic cathode had to rely mainly on neutral gas to heat the emitter. Because thermionic emission was in exponential relation with emitter temperature, the temperature fluctuation was then amplified to cause larger fluctuation in total current as well as in total discharge power, which led to deeper fluctuation in temperature. Regarding the heating of both neutral gas and emitter, an instability model showed that multiple unnoticed factors could determine the onset of instability, including the thermal inertia of neutral gas and emitter, the heat transfer from discharging plasma to neutral gas, the heat loss of cathode and the response time of power supply. As a result of this instability, the plume ion energy was elevated from <50eV to 30∼120eV due to the fluctuating density on cathode exit and fluctuating discharge voltage. It was estimated that the increased ion energy could accelerate the keeper erosion by 4∼22 times. • Low current cathodes were unstable when current was reduced to a threshold. • This instability was manifested by voltage and current oscillations of ∼Hz order. • Reasons included thermal inertia, plasma-gas heat transfer, power response time. • The discovered this instability could produce >60eV energetic ions. • It was estimated to speed up sputtering erosion by 4–22 times. [ABSTRACT FROM AUTHOR]

Previous simulation studies have revealed the formation of magnetosheath filamentary structures by foreshock energetic ions. We report Cluster and Double Star observations of three such events triggered by a foreshock bubble, a hot flow anomaly and a traveling foreshock, respectively. In each case, in association with the onset of foreshock energetic ions, the magnetosheath energetic ion fluxes have quasi‐periodic modifications. Their azimuthal and pitch angular distributions indicate that these populations flow into the magnetosheath along the magnetic field lines. As a result, filamentary plasma structures form and display as a series of ion density and pressure oscillations anticorrelated to temperature oscillations. Moreover, our statistical analyses of their properties show that filamentary structures primarily form in the magnetosheath with the magnetic field lines connecting to the quasi‐parallel bow shock and under favorable formation conditions similar to those of foreshock transients. The distributions of the angles between the filamentary structure normals and the local magnetic field directions peak at 80°–90°. The transverse sizes of those filaments are in the range of 0.2–1.6 RE. Magnetosheath filamentary structures are often associated with large‐amplitude ion density and temperature perturbations comparable to the unperturbed background levels. Key Points: The formation of magnetosheath filamentary structures can link to various foreshock phenomenaFilamentary structures form under favorable solar wind conditions similar to those of foreshock transientsFilamentary structures are often associated with large‐amplitude ion density and temperature perturbations [ABSTRACT FROM AUTHOR]

Effects of the energetic-ion-driven Geodesic Acoustic modes (GAM and E-GAM) on the toroidally passing energetic ions and the concomitant change of the neutron yield of beam-plasma fusion reactions in tokamaks are considered. It is shown that due to large perturbations of the plasma density, the resonant energetic ions driving the instability can be considerably slowed down for a few tens of the particle transit periods, which is much less than the collisional slowing down time. The time of the collisionless slowing down is actually determined by the period of the particle motion within the resonance island arising because of the GAM / E-GAM. Being trapped in the island, the resonant particles can not only lose their energy but also gain it. One more effect of GAMs is the flattening on the distribution function of the resonant particles. Due to conservation of the canonical angular momentum during a GAM / E-GAM instability, the change of the particle energy is accompanied by a radial displacement of the resonant particle for a distance up to the poloidal Larmor radius of energetic ions. The particles are displaced inwards or outwards, depending on the direction of their motion along the magnetic field. Expressions describing the change of the neutron yield due to GAM modes are derived. It is found that the distortion of the velocity distribution of the resonant particles can lead to a considerable drop of the neutron emission even when effects of the particle radial displacement are small. The developed theory is applied to an E-GAM experiment on the DIII-D tokamak. Relations for the period of the motion within the resonance island of passing (both well passing and marginally passing) particles and the width of the resonance of the energetic particles with GAM modes and low-frequency Alfvé modes are derived.

The impact of electron cyclotron current drive (ECCD)-driven current on toroidicity-induced Alfvén eigenmodes (TAEs) in experiments on the AUG tokamak is investigated numerically. The dynamical evolution of the plasma profiles and equilibria are modelled with European transport solver, while ion cyclotron resonance heating-accelerated H-minority ions exciting TAEs are assessed with the PION code. TAEs, their drive and damping are computed with the codes CASTOR and CASTOR-K. In the set of discharges analysed, two groups of TAEs are observed, differing in frequency and radial location. Experimental observations show that when counter-ECCD is applied the higher frequency group of approximately 150 kHz is suppressed, while the lower frequency modes of 125 kHz are amplified. When co-ECCD is applied, depending on the location of the ECCD current deposition layer, both groups of TAE can be suppressed. Numerical calculations of energetic particle drive and thermal plasma damping show that neither one effect could explain the variety of the experimental observations. The fine balance between the drive, sensitive to the TAE position, and the radiative and continuum damping effects could only explain the experiment if the effects are considered all together.

The mechanism of rapid frequency chirping for neoclassical tearing modes (NTMs) is studied. Resonance between NTMs and trapped energetic ions can provide an additional torque to change the evolution of frequency. Whether the frequency rises or falls depends on the direction of island propagation. If the island propagates in the direction of ion diamagnetic drift, the frequency will be increased dramatically and rapidly. If the island propagates in the direction of electron diamagnetic drift, the frequency will be reduced to a lower value. The predicted chirping time is consistent with experimental results in DIII-D (Liu et al 2020 Nucl. Fusion 60 112009). [ABSTRACT FROM AUTHOR]

Understanding the impact of energetic ion irradiation on semiconductor materials and devices is essential for optimizing their electronic applications. This knowledge contributes to the broader goal of tailoring material properties to enhance the overall performance and reliability of semiconductor devices. In this study, we investigate the impact of 1.2 MeV Ar8+ irradiation on Au/n-Si Schottky barrier structures in-situ, as a function of ion irradiation fluence. Electrical characterization was performed in-situ on a single sample to mitigate any variability in device parameters between samples. It is observed that ion irradiation results in an increased Schottky barrier height with a reduction in reverse leakage current. The behavior is attributed to dopant deactivation by the energetic ion irradiation-induced defects near the interface. These results underscore the importance of understanding ion irradiation impacts on semiconductor devices, providing valuable insights for optimizing Schottky diodes in electronic applications. [ABSTRACT FROM AUTHOR]

A method is proposed for tomography of the distribution function of energetic ions that are adiabatically trapped in an open magnetic trap, according to the diagnostic data by the method of collective Thomson scattering. This method is based on measurements of the scattering spectra from successive plasma cross sections corresponding to different values of the magnetic-field strength along a single line of force. It is shown that the problem of restoring the ion distribution function in the velocity space from the measurement data in this situation is reduced to an integral equation of the first kind that allows an analytical solution. Several ways to construct exact and approximate solutions of the resulting integral equation are considered. [ABSTRACT FROM AUTHOR]

Zinc oxide has been the most versatile compound semiconductor, which is applied in diverse streams. Ion beams have been highly sophisticated and innovative tool for material modification and further characterization. In this article, we have systematically reviewed the ion beam synthesis, modification and further applications of ZnO thin films and nanocomposites. ZnO thin films synthesized, using low-energy ion beams, exhibit excellent quality. Ion implantation of ZnO leads to the improvement of electrical, optical and magnetic properties. Inert ion bombardment, on the one hand, results in the formation of uniform surface patterning on ZnO and on the other, produces nucleation centres for nanostructure growth. ZnO thin films also exhibit substantial radiation resistance, thus upon swift heavy ion irradiation, tuning of various properties can be explored with minimal/recoverable damage to the crystal lattice. In a few such studies, room temperature ferromagnetism, dissolution of metal cluster and recrystallization of ZnO have been observed. The precision of energetic ion beams and robustness of ZnO and its nanostructures have been explored for applications such as resistive random access memory, creation of hydrophophic and hydrophilic surfaces and dye degradation. [ABSTRACT FROM AUTHOR]

We model the dynamics of energetic magnetospheric ions in the perturbed electromagnetic fields near Jupiter's moon Europa. The inhomogeneities in the fields near Europa are generated by the induced dipole field from the moon's subsurface ocean as well as the Alfvénic plasma interaction with its ionosphere and induced field. Inhomogeneities in Europa's ionosphere at various length scales generate substantial asymmetries in the mass loading process that further complicate the structure of the moon's electromagnetic environment. In our study, the electromagnetic fields near Europa are obtained from an established hybrid model, whereas a particle tracing tool is applied to analyze the precipitation of the three most abundant energetic ion species (hydrogen, oxygen, and sulfur) onto the moon's surface at various energies from 1 keV up to 5 MeV. To isolate the contributions of the induced dipole and ionospheric mass loading to the field perturbations and the resulting precipitation patterns, we consider multiple field configurations of successively increasing complexity. For ion energies in the kiloelectron volt regime, magnetic field line draping effectively shields large portions of Europa's surface against energetic ion impacts and drastically alters the shape of the precipitation patterns, compared to uniform fields. The fine structure of these patterns strongly depends on the complexity of the applied ionosphere model. Only in the megaelectron volt regime, the precipitation patterns are qualitatively similar for uniform and draped fields. However, the precipitation of megaelectron volt ions onto Europa is still not homogeneous, since the strong magnetospheric field keeps ion gyroradii much smaller than the moon's radius. Key Points: A combination of hybrid simulations and particle tracing is applied to study the dynamics of energetic magnetospheric ions near EuropaEnergetic ion dynamics near Europa are strongly affected by the Alfvénic field perturbations near the moonIn the kiloelectron volt regime, field line draping due to ionospheric mass loading effectively shields Europa's surface against energetic ions [ABSTRACT FROM AUTHOR]

In all kinetic simulations of the solar wind interaction with the moon, dayside absorption of the core solar wind protons results in the formation of a numerically unstable vacuum in the tail requiring a fix. In Omidi et al. (2019, https://doi.org/10.1029/2018JA026243) it was shown that replacing the vacuum with a cold plasma results in unacceptable magnetic fields when compared to observations. It was also demonstrated that when the presence of energetic ions in the solar wind is accounted for, the tail is no longer a vacuum but contains a low‐density plasma. In addition, the resulting magnetic fields are in excellent agreement with the observations including the presence of the compressional wake. Poppe (2019) shows results from the Amitis, which employs a different vacuum model and produces a magnetic field profile in the central tail that agrees with observations. However, the results do not account for the presence of low‐density plasma in the tail and the formation of the compressional wake. To explain these shortcomings, Poppe (2019) questions the existence of plasma in the tail and attributes the compressional wake to lunar crustal fields. Here we address the criticism of plasma observations and provide additional data from ARTEMIS spacecraft that demonstrates the compressional wake is an inherent part of the lunar tail structure. As such, the Amitis vacuum simulations do not capture the full physics of the interaction. In contrast, when the energetic protons are included in the model, all aspects of the lunar tail structure are accounted for. Key Points: Lunar tail contain low‐density plasmaThe compressional wake is an inherent part of the lunar tailEnergetic ions dominate the interaction [ABSTRACT FROM AUTHOR]

We use the results of 3‐D electromagnetic hybrid (kinetic ions and fluid electrons) simulations and observations by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) /Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft to investigate the nature of the solar wind interaction with the moon and the resulting wake and tail structure. In the absence of a global magnetic field and an atmosphere at the moon, this interaction is due to the absorption of the solar wind plasma on the dayside and the means by which the resulting cavity in the tail is refilled. To explore this process, we conducted simulations of specific case studies well‐monitored by the ARTEMIS spacecraft. Preliminary runs revealed that when the solar wind core plasma is driving the interaction, the results deviate significantly from observations. When the small population of solar wind energetic ions is incorporated in the model, the observations are reproduced much better. Simulations with different density or energy of energetic ions show considerable changes in the results indicating their dominance in establishing the electromagnetic properties of the tail. In contrast, the results show less sensitivity to the solar wind flow speed. Here we conclude that the structure of the interaction region consists of compressional and rarefaction wakes and a central tail region with areas of enhanced and possibly reduced magnetic field level. The compressional wake diverts the flow away from the tail, and its presence is found to be highly time dependent while the rarefaction wake diverts the flow toward the tail and is found to be a semipermanent feature of the lunar interaction region. Key Points: Energetic ions dominate solar wind interaction with the moonLunar tail is populated with energetic ionsLunar wake structure consists of compressional and rarefaction fast magnetosonic waves [ABSTRACT FROM AUTHOR]

Abstract We examine the dynamics of energetic magnetospheric ions in the highly perturbed and asymmetric electromagnetic environment of the Jovian moon Callisto. The Alfvénic interaction of the (nearly) corotating magnetospheric plasma with Callisto's ionosphere and induced dipole generates electromagnetic field perturbations near the moon, the structure of which vary as a function of Callisto's orbital position. For this study, these perturbations are obtained from the AIKEF hybrid model (kinetic ions, fluid electrons) which has already been successfully applied to Callisto's local plasma environment (Liuzzo et al., 2015, 2016, 2017). To isolate the influence of Callisto's ionosphere and induced dipole field on energetic ion dynamics, we analyze the trajectories of energetic hydrogen, oxygen, and sulfur ions exposed to various configurations of the locally perturbed electromagnetic fields. We present spatially resolved surface maps that display accessibility of Callisto to these ion populations for select energies from 1 keV to 5000 keV. The Alfvénic plasma interaction with (i) Callisto's induced magnetic field, (ii) Callisto's ionosphere, and (iii) the combination of both, all leave distinct imprints in these accessibility patterns. Draping of the magnetospheric field around Callisto's ionosphere partially shields the moon's trailing (ramside) hemisphere from energetic ion impacts, and the induced field tends to focus energetic ion impacts near Callisto's Jupiter-facing and Jupiter-averted apices. Depending on the nature of Callisto's Alfvénic plasma interaction, the accessibility of its surface to energetic protons may evolve non-monotonically with increasing energy. We also present maps of energetic ion accessibility and the resulting energy deposition onto Callisto at the time of the Galileo C3, C9, and C10 flybys. Our findings show that the shielding of Callisto's surface from energetic ion impacts is most effective during flybys that took place while the moon was located at an intermediate distance to the center of Jupiter's magnetospheric current sheet. In this case, the ionosphere and induced dipole field both make substantial contributions to the electromagnetic field perturbations near Callisto. [ABSTRACT FROM AUTHOR]

A new composite analysis of ∼13 years of Cassini's Charge Energy Mass Spectrometer measurements, presented by Allen et al. (2018, https://doi.org/10.1029/2018JA025262), suggests that the asymmetrically distributed suprathermal He++ in Saturn's magnetosphere is due to Dungey cycle related reconnection and Kelvin‐Helmholtz instabilities that provide paths to the solar wind plasma to reach distances even deep in the inner magnetosphere and accumulate in the ring current region, together with the internally sourced plasma. The results provide a significant addition to the ongoing discussions concerning the contribution of the solar wind input to the dynamics of an otherwise rotationally driven system, such as Saturn's magnetosphere. Key Points: Detection of He++ in Saturn's magnetosphere points to solar wind entry due to Dungey cycle reconnection and Kelvin‐Helmholtz instability [ABSTRACT FROM AUTHOR]

A statistical study of the energetic proton environment at Titan's orbit as captured by the MIMI/LEMMS and MIMI/CHEMS instruments is performed. The data analyzed cover all the dedicated flybys of Titan by Cassini as well as the orbit crossings that happen far from the moon. The energetic environment is found to be highly variable on timescales comparable to that of the duration of a flyby. Analysis of H+ ion fluxes reveals a weak asymmetry in Saturn local time with the highest fluxes occurring in the premidnight sector of the magnetosphere. A correlation between the energetic ion fluxes and the location of Cassini in the magnetosphere with respect to the center of the current sheet can be observed. Finally, an empirical model of proton spectra for energies above 20 keV is derived based on fits to Kappa distribution functions. This model can be used to better understand the interaction of Titan with the magnetosphere and the energy deposition by energetic particles below the main ionospheric peak. Key Points: Energetic particle environment at Titan's orbit is highly variableIon data present SLT asymmetry with higher fluxes in the premidnight sectorDerivation of empirical model of ion spectra based on Kappa distribution function is presented [ABSTRACT FROM AUTHOR]

During February 15-16, 2014, the energetic electron spectrogram for four successive inner radiation belt crossing show clearly the electron zebra structures and their time evolution which last for about 17 h. Unfortunately, the time of flight (TOF) in RBSPICE measurement is turned off below 3RE, and the ion measurement is contaminated by electrons. Thus in this study we studied the differences between the ion and electron zebra stripe structures and their time evolution using simple theory and test particle simulation, combining the electron measurement from RBSIPICE onboard Van Allen Probes. Theoretical analysis predicts that the ion zebra stripe structures should lie at a higher energy range than the corresponding electron zebra stripe structures due to that the directions of gradient B drift and corotation E×B drift are the same for electrons while opposite for ions. Test particle simulation with the dipole magnetic field and Volland-Stern electric field model have shown that the ion and electron zebra stripe structures could be produced by the convection electric field penetrating into the inner magnetosphere in this event, with their time evolution determined by total drift velocity that are different for ions and electrons. The predicted differences between the ion and electron zebra stripe structures are partially verified through observation. The ion zebra stripe structures could have potential influence to the ring current. [ABSTRACT FROM AUTHOR]

In this paper, we report on ultra-low power consuming single poly floating gate direct radiation sensors. The developed devices are intended for total ionizing dose (TID) measurements and fabricated in a standard CMOS process flow. Sensor design and operation is discussed in detail. Original array sensors were suggested and fabricated that allowed high statistical significance of the radiation measurements and radiation imaging functions. Single sensors and array sensors were analyzed in combination with the specially developed test structures. This allowed insight into the physics of sensor operations and exclusion of the phenomena related to material degradation under irradiation in the interpretation of the measurement results. Response of the developed sensors to various sources of ionizing radiation (Gamma, X-ray, UV, energetic ions) was investigated. The optimal design of sensor for implementation in dosimetry systems was suggested. The roadmap for future improvement of sensor performance is suggested. [ABSTRACT FROM AUTHOR]

Magnetohydrodynamic waves, having unusual dispersion and resonance properties, have been found within the framework of the linear kinetic theory. This modification is due to the energetic ion component of the cosmic plasma. Calculations (estimates) illustrate the possibility of this modification by H, He, and O ions, for example, in the magnetosphere of the Earth. [ABSTRACT FROM AUTHOR]

In this paper, we report on ultra-low power consuming single poly floating gate direct radiation sensors. The developed devices are intended for total ionizing dose (TID) measurements and fabricated in a standard CMOS process flow. Sensor design and operation is discussed in detail. Original array sensors were suggested and fabricated that allowed high statistical significance of the radiation measurements and radiation imaging functions. Single sensors and array sensors were analyzed in combination with the specially developed test structures. This allowed insight into the physics of sensor operations and exclusion of the phenomena related to material degradation under irradiation in the interpretation of the measurement results. Response of the developed sensors to various sources of ionizing radiation (Gamma, X-ray, UV, energetic ions) was investigated. The optimal design of sensor for implementation in dosimetry systems was suggested. The roadmap for future improvement of sensor performance is suggested.

Nanocrystalline Cadmium oxide (nc-CdO) thin films were deposited on indium tin oxide (ITO) coated glass substrates by the sol–gel spin coating technique. The prepared films were irradiated with energetic ions for two different fluences for inducing electronic excitations and/or ionizations. Films are investigated for structural studies using grazing incidence X-ray diffraction (GIXRD) and for optical studies by UV–vis absorption spectroscopy. The structural study reveals that the films are polycrystalline in nature with cubic phase and the average crystallite size is in the range 24–27 nm, which exhibit insignificant change upon irradiation. However, films show an increase in the band gap from 2.58 ± 0.02 to 2.72 ± 0.02 eV with increasing in the ion fluence. The initial high value of the band gap is attributed to Burstein–Moss (BM) shift, while the increase in band gap upon irradiation is explained by disorder induced valence band tailing states created by high density of electronic excitations in the lattice. [ABSTRACT FROM AUTHOR]

Decomposition of indium oxide nanoparticles (IONPs) sandwiched between zinc oxide (ZnO) thin films by energetic ions is reported. Multi-layers thin films were deposited using RF magnetron sputtering at room temperature, consisting two thin indium oxide layers sandwiched between three ZnO layers. Films exhibit very high transparency in the visible region. A sharp near band edge absorption with exciton absorption peak in the film annealed at the highest temperature was also observed. The structural and optical properties reveal that the as-deposited films show the formation of IONPs around the interface, which further grow upon increasing in annealing temperature. However, irradiation induces the decomposition of IONPs for the possible formation of single phase indium doped ZnO (IZO). The mechanism of the decomposition of IONPs is understood by the creation of ion tracks in IO. The track radius ( R e ) of 5.9 nm is calculated in the framework of thermal spike model. Therefore, the IONPs with diameter≤2 R e decomposed or amorphized between the crystalline ZnO layers; while the IONPs with diameter>2 R e show reduction in size by the electronic sputtering from the IONPs surface under the thermo-elastic effects. [ABSTRACT FROM AUTHOR]

The so-called “bucket transport” of energetic ions — the spatial mixing of these ions due to spatial displacement of resonances — is studied with special attention to quasi-steady-state magnetic perturbations. A Hamiltonian formalism suitable to the case when the resonance displacement results from the collisional slowing down of the particles and the temporal evolution of the safety factor profile is suggested. The energy flux produced due to the bucket transport is shown to be considerable in configurations with low shear. It is shown that the bucket transport flux associated with magnetic islands tends to be localized at some distance from the islands. The bucket transport caused by perturbations with non-zero frequencies is also discussed. [ABSTRACT FROM AUTHOR]

It is shown that (i) the destabilization of global Geodesic Acoustic modes (GAM or E-GAM) by passing energetic ions in tokamaks can be accompanied with a considerable energy transfer from these ions to the mode; (ii) the mode-induced slowing down of the energetic ions leads to a radial shift outwards/inwards of the ions moving in the direction counter to/of the plasma current, in spite of the fact that the canonical angular momentum of the particles is conserved during GAMs. Some practical consequences of these phenomena are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Cationic polymer PEI-CyD is doped with Nd by plasma technology to produce the gene vector: Nd@PEI-CyD. Luciferase expression and EGFP transfection experiments performed in vitro reveal that Nd@PEI-CyD has significantly higher transfection efficiency than lipofectamine 2000 and PEI-CyD and the mechanism is studied and proposed. The rare-earth element, Nd, stimulates the energy metabolism of cells, enhances cell uptake of complexes/pDNA, and regulates the cellular pathways. These special features suggest a new strategy involving metal-incorporated non-viral gene vectors. [Copyright &y& Elsevier]

Silicon carbide (SiC) detectors were used to analyze the multi-MeV ions of the plasma produced by irradiation of various targets with a 300-ps laser at intensity of 1016 W/cm2. The SiC detectors were realized by fabricating Schottky diodes on 80 μm epitaxial layer. The low dopant concentration and defect density of the epilayer allowed the realization of good performance detectors. The use of SiC detectors ensures the cutting of the visible and soft ultraviolet radiation emitted from plasma enhancing the sensitivity to very fast ions. The time-of-flight spectra obtained by irradiating different targets show a peak associated to protons and various peaks relative to different charge states of ions. Processing of the experimental data allows to estimate the energies of the protons and of the different ions emitted from laser-induced plasma. The SiC detector results are compared with the ones obtained by Ion Collector and a Thomson Parabola spectrometer. [ABSTRACT FROM PUBLISHER]

In this paper we examine the elemental composition of the 0.1 - 1 MeV nucleon interplanetary heavy ions from H to Fe in corotating interaction regions (CIRs) measured by the SIT ( Suprathermal Ion Telescope) instrument. We use observations taken on board the STEREO spacecraft from January 2007 through December 2010, which included the unusually long solar minimum following Solar Cycle 23. During this period instruments on STEREO observed more than 50 CIR events making it possible to investigate CIR ion abundances during solar minimum conditions with unprecedented high statistics. The observations reveal annual variations of relative ion abundances in the CIRs during the 2007 - 2008 period as indicated by the He/H, He/O and Fe/O elemental ratios. We discuss possible causes of the variability in terms of the helium focusing cone passage and heliolatitude dependence. The year 2009 was very quiet in CIR-event activity. In 2010 the elemental composition in CIRs were influenced by sporadic solar energetic particle (SEP) events. The 2010 He/H and He/O abundance ratios in CIRs show large event-to-event variations with values resembling the SEP-like composition. This finding suggests that the suprathermal SEPs could be the source population for CIR acceleration. [ABSTRACT FROM AUTHOR]

Abstract: During a magnetopause crossing by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft, signatures of magnetic reconnection and of accelerated flows were observed. The maximum magnetic shear model of the reconnection X-line suggests that the spacecraft passed very close to the reconnection line. At the inner edge of the low latitude boundary layer (LLBL), accelerated ions are observed, which are magnetically connected to the quasi-parallel bow shock and travel towards the northern cusp region. However, a short time later the THEMIS satellite crossed the reconnection line, onto field lines, which map out to the quasi-perpendicular bow shock (or, the weak quasi-parallel bow shock very far downstream). At these times there is no significant difference in the energetic ion flux component observed coming from the shock versus from the cusp. These signatures suggest that, at least in some cases, energetic particles observed in the cusp regions originate at the quasi-parallel bow shock. [Copyright &y& Elsevier]

Abstract: Ambiguities introduced by the inconsistent definitions of the low and high altitude cusp lead to the inconsistency that at low altitudes the region commonly known as the cusp does not include boundary layer plasmas, but at high altitudes it does. Here we examine plasma data from two high altitude cusp intervals where ∼100keV ionospheric ions were observed. We show that the data are an average over an interval that includes plasma from both boundary layer and newly injected solar wind plasmas. We find that the ∼100keV ionospheric ions reported in the high altitude cusp are energized by well-known magnetospheric processes bringing energetic ions to the dayside boundary layers. We conclude that there is no need to postulate new processes associated with waves in diamagnetic cavities commonly found in the high altitude cusp to explain the observation of ∼100keV ionospheric ions found there. [Copyright &y& Elsevier]

Abstract: We examined the temporal variations of the geomagnetic field and energetic ions at geosynchronous altitudes associated with substorms during the nighttime using a superposed epoch analysis timed by Pi2 onset. We focused on the first 10min intervals of Pi2 onset and on subsequent intervals to study the substorm expansion. We conclude that the first 10min interval of Pi2 onset is a transitional state of the substorm dominated by MHD processes associated with earthward flow and its bifurcation. Intervals of field line variations following the first 10min were well organized by dipolarization (substorm current wedge) due to the reduced cross-tail current. We also show that energetic ion regions localized in the local time sector from 2000 to 0000LT in the first 10min intervals of Pi2 onset expanded to the post-midnight sector, reaching 0400LT within 20min after Pi2 onset. We conclude that the expansion of the energetic plasma regions can be attributed to the inflation of the inner magnetosphere during dipolarization. [ABSTRACT FROM AUTHOR]

Abstract: A new ion identification method for ΔE−E telescopes is presented. The method works by counting data points under ΔE(E) curves on ΔE−E diagrams. These curves are obtained by simulating the telescope response to a flux of energetic ions. The method is checked against three published methods applied to several experimental data sets. [Copyright &y& Elsevier]

Abstract: Observations of energetic ions of solar origin in the heliosphere suggest the existence of two main energization sites with different physical mechanisms: (1) impulsive mechanism on the flaring coronal magnetic field – via resonant interaction, presumably with low-frequency electromagnetic waves; (2) gradual mechanism around the propagating, interplanetary shock – by interaction with quasi-static inhomogeneous electromagnetic structure and low-frequency Alfvenic turbulence. While the coronal process enhances a subset of rare elements, the interplanetary interaction energizes most of the elements of coronal/solar wind origin. In the impulsive events, according to recent models, a significant fraction of heavy elements which reside on the active flaring flux rope is energized; the resonant interaction operates mainly on Fe and other heavy elements with high charge states. In the gradual events main energization occurs close to the Sun at low Mach numbers; significant interplanetary enhancement of energetic ion fluxes requires a narrow scale length in the propagating shock. Coupling of both processes results in the final heliospheric distribution function of the heavy elements. The enhanced energetic heavy ion population may have a profound impact on human space exploration in the interplanetary space as well as in the resulting trapped radiation in the magnetosphere. [Copyright &y& Elsevier]