Electron Beam Source Research Articles

Scientific explanation of e+ and Weyl fermion for injecting semiconductor devices

The scientific explanation of utilizing the positron and Weyl fermion in semiconductors is presented. In view of the slow e+ beam-generation development for imaging technology alongside the Weyl fermion which carries charge like an electron, but has no mass, thus moves much faster, injecting semiconductor devices is addressed. The information gained from this prediction has allowed the broadening of its implementation to semiconductor technology with electronic excitation using sources other than e-. Developing the positron microbeam and Weyl fermions can be described with the concept of type I positron beam source is an alternative source of electron beam, thus harnessing the generation of γ-ray radiations inside the semiconductor heterostructures with indicating e+ and e− interaction with materials are different and type II Weyl fermions. Thus, the properties of positrons and Weyl fermion are considered suitable for carrier transport in optoelectronics. Perspectives of the development of alternative beam source for super-transport are provided.

Evaluation of Electronic and Crystal Structures of Li-Rich Layered Oxide Cathode Using Combinations of Exes, XPS, and PDF Analyses

Lithium-rich layered oxides (LLOs) have attracted attention as high-capacity cathode materials for lithium-ion secondary batteries. Its unique charge-compensation mechanism and structure changes during delithiation and lithiation yield a large capacity. LLOs reversibly extract and insert ~1 mol of Li (> 250 mAh/g) per Li1+x Me 1 − x O2 (Me=Ni, Co, Mn) notation. In contrast, conventional layered oxides such as LiCoO2 reversibly extract and insert ~0.6 mol (~160 mAh/g), which is limited by the irreversible change of the host structure by the excessive Li extraction. However, such a large amount of delithiation in LLOs still induces various structural changes. Although various structure analyses, including conventional XRD, have revealed the structural changes of LLOs accompanying charging and discharging, the inherently disordered structure of LLOs requires a more elaborate experimental approach to elucidate the relationship between the structural changes and electrode properties. Because conventional XRD only provides structure information of the well-ordered crystalline phase, the structure evolution of LLOs and their charging/discharging mechanisms should be elucidated to reveal such disordered structures. Pair distribution function (PDF) analysis, which is an advanced XRD technique using X-ray total scattering, enables quantitative observations of the short-, medium-, and long-range orders with high spatial resolutions in real space even from highly disordered structures simultaneously. In addition, spectroscopic analyses have revealed the unique charge compensation mechanisms associated with the high capacity of LLOs. In LLOs, the contribution of O anions is a key factor for the reversible high capacity. Another consideration is the valence bands of both O and Me from simultaneous observations of constituent elements, since the O 2p and Me 3d orbitals are hybridized. Soft X-ray emission spectroscopy (SXES) is a useful technique to observe the electronic structure of multiple elements simultaneously. Among them, electron-induced X-ray emission spectroscopy (EXES) is an accessible technique using laboratory X-ray or electron beam sources for excitation. In this study, we performed EXES and PDF analyses along with X-ray photoelectron spectroscopy (XPS) on the same states of samples for the LLO cathode, 0.4Li2MnO3−0.6LiNi0.5Mn0.5O2, to reveal the relation between the charge compensation mechanism and changes in the crystal structure. The PDF analysis suggested that charging caused Me cations to migrate to the octahedral and tetrahedral sites in the Li layer. EXES independently observes the energy distribution of each orbital, revealing their specific roles in the charge compensation accompanying electrochemical charging and discharging. EXES with the aid of XPS revealed that the charge was compensated by Ni, Mn, and O. The contribution from each element depended on the charging/discharging state. The changes in the electronic/crystalline structures that yield the unique charge-compensation mechanism and the large capacity of the LLO electrode will be discussed.

Monte Carlo source verification of Elekta Synergy for pMLC collimated electron beams

IntroductionIn previous works, an electron beam source was developed that models its energy spectrum with a Lévy distribution. This source is used in BEAMnrc Monte Carlo simulation. It was benchmarked against water tank measurements for electrons delivered through an applicator collimation system, and it was found to agree with 2%/2 mm. This study uses this electron source further by investigating its ability to simulate electrons collimated by the photon multi-leaf collimators for MERT applications. Simulated and Gafchromic EBT3 depth dose and profile data were compared. MethodMeasured data were obtained from film exposures in a mini phantom with water-equivalent slabs at SSDs of 60 and 70 cm, respectively. Output factors and R90 values were calculated from film strip data taken in the depth direction. Corresponding dose data were simulated in BEAMnrc to obtain phase-space files for each beam and used in DOSXYZnrc to obtain dose data in a 3D water tank with 2 mm side length subvoxels. ResultsSimulation data corresponded with film data within 3 %/2 mm in most cases. Uncertainties in film measurements prevent a more accurate agreement. The output factors showed good agreement and could be fitted satisfactorily with an analytic function. A clinical example of a scalp treatment showed good agreement between simulated and film data. ConclusionIt is concluded that the electron source with the Lévy-based energy distribution can model electron dose for photon multi-leaf collimated electron beams within 3 %/2 mm.

Extending the Operating Pressure Range of a Forevacuum-Pressure Plasma-Cathode Ribbon Electron Beam Source

Extending the Operating Pressure Range of a Forevacuum-Pressure Plasma-Cathode Ribbon Electron Beam Source

Emission characteristics of a forevacuum plasma-cathode source of wide-aperture pulsed electron beam with layer (mesh) stabilization of emission plasma

Research of emission characteristics of a pulsed forevacuum plasma electron source with layer (mesh) stabilization of emission plasma boundary has been carried out. Generation of a pulsed wide-aperture electron beam is provided by DC accelerating voltage (1–10 kV) and pulse-periodic formation of emission plasma by a cathodic arc with current 5–80 A, pulse duration 500–600 μs. Pressure (4–30 Pa) and the type of working gas (N2, O2, Ar, He, Kr) significantly influence on the emission characteristics of the forevacuum plasma electron source. An increase in the gas pressure and the use of gas with larger ionization cross-section provide an increase in the electron emission current. At low pressure (below a certain threshold value, which determined by the type of gas) an increase in the discharge current leads to an increase in the efficiency of electron emission. But at pressures more than the threshold value the emission efficiency decreases as the discharge current increases. The influence of pressure and type of gas on the emission characteristics are caused by the ion flux from the beam plasma which is formed due to ionization of gas by accelerated beam's electrons.

Liquid dosimeter with sensitivity in low-kGy range for the characterization of a new module for EB wastewater treatment

Abstract In recent years, the use of low-energy electrons in various ecological and biotechnological applications has become increasingly relevant. One important application is the treatment of wastewater, wherein highly reactive species produced by water irradiation are used to oxidize pollutants. Low-energy electron irradiation has several advantages, such as minimal demands on radiation protection and electron beam (EB) source dimensions. However, to play into the main advantages of this technology and keep it economically viable, it is necessary to keep the absorbed dose as low as possible. This calls for a liquid dosimeter with sensitivity in the single digit kGy range. An extract from natural Hibiscus sabdariffa (Roselle) has been reported to show a radiochromic effect in this dose range. In the present work, Roselle dosimeter solutions were closely investigated and optimized to characterize a new module for EB wastewater treatment. Upon EB irradiation, the dosimeter solution demonstrated a dose-dependent fading in color, making it useful in the 0.3–7.5 kGy dose range.

A study of hollow-cathode electron beam source surface flashover discharge and suppression

As surface flashover discharge limits the performance of hollow-cathode electron beam sources, this work systematically investigates the surface flashover discharge in the hollow-cathode discharge process based on electrostatic field simulations. Experimental research is conducted on designing and investigating hollow cathode discharge cavities featuring structures to prevent surface flashover, both single- and multi-gap. Theoretical analysis found that the vacuum surface flashover discharge will cause an abnormal breakdown phenomenon along the wall of the insulating sleeve. The surface flashover, once formed, would develop dramatically, thus suppressing the formation of hollow-cathode discharge and becoming the main form of discharge. To eliminate the abnormal flashover breakdown, an effective suppression structure is designed regarding the triple point of the surface flashover. Through the special design, the triple points in the corners are always hidden by recessing the corner of the insulator in a notch. Moreover, corrugated structures along the insulating surface are studied, and the proper rectangular slots are designed in the inner insulating surface. The experimental results also indicate that after adopting the insulation scheme, the breakdown voltage of the discharge cavity and its working stability are greatly improved.

A study of pulsed high voltage driven hollow-cathode electron beam sources through synchronous optical trigger

In this study, a pulsed, high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure, low cost, and easy triggering. To validate the new design, the characteristics of hollow-cathode discharge and electron beam characterization under pulsed high voltage drive are studied experimentally and discussed by discharge characteristics and analyses of waveform details, respectively. The validation experiments indicate that the pulsed high voltage supply significantly improves the frequency and stability of the discharge, which provides a new solution for the realization of a high-frequency, high-energy electron beam source. The peak current amplitude in the high-energy electron beam increases from 6.2 A to 79.6 A, which indicates the pulsed power mode significantly improves the electron beam performance. Besides, increasing the capacitance significantly affects the high-current, lower-energy electron beam more than the high-energy electron beam.

Direct Observation of Sub-Poissonian Temporal Statistics in a Continuous Free-Electron Beam with Subpicosecond Resolution.

We present a novel method to measure the arrival time statistics of continuous electron beams with subpicosecond resolution, based on the combination of an rf deflection cavity and fast single electron imaging. We observe Poissonian statistics within time bins from 100 to 2ns and increasingly pronounced sub-Poissonian statistics as the time bin decreases from 2ps to 340fs. This 2D streak camera, in principle, enables femtosecond-level arrival time measurements, paving the way to observing Pauli blocking effects in electron beams and thus serving as an essential diagnostic tool toward degenerate electron beam sources for free-electron quantum optics.

Electron beams traversing spherical nanoparticles: Analytic and numerical treatment

We present an analytic, Mie theory-based solution for the energy loss and the photon-emission probabilities in the interaction of spherical nanoparticles with electrons passing nearby and through them, in both cathodoluminescence and electron energy-loss spectroscopies. In particular, we focus on the case of penetrating electron trajectories, for which the complete fully electrodynamic and relativistic formalism has not been reported as yet. We exhibit the efficiency of this method in describing collective excitations in matter through calculations for a dispersive and lossy system, namely a sphere described by a Drude permittivity. Subsequently, we use the analytic solution to corroborate the implementation of electron-beam sources in a state-of-the-art numerical method for problems in electrodynamics, the discontinuous Galerkin time-domain (DGTD) method. We show that the two approaches produce spectra in good mutual agreement, and demonstrate the versatility of DGTD via simulations of spherical nanoparticles characterized by surface roughness. The possibility of simultaneously employing both kinds of calculations (analytic and numerical) facilitates a better understanding of the rich optical response of nanophotonic architectures excited by fast electron beams. Published by the American Physical Society 2024

Measurement of a force imparted to a magnetic nozzle by electron diamagnetism

An electron-beam plasma source consisting of a hot filament is installed near the throat of the magnetic nozzle immersed in a vacuum chamber. The low plasma potential of about 5 V is formed over the region of the measurement in the weakly ionized and partially magnetized argon plasma expanding along a magnetic nozzle; an electric field is much smaller than a pressure gradient, providing a force balance between the electron pressure and the magnetic pressure. This condition leads to a negligible electron E×B drift current and nearly pure diamagnetism. Measurement of the force exerted on the magnetic nozzle is performed by attaching only the solenoid to a pendulum thrust balance, clearly demonstrating the presence of the force induced by the purely diamagnetic current, which is the major contributor to the thrust generation in the magnetic nozzle plasma thruster. This indicates that the thrust can be generated only by the electrons expanding in the magnetic nozzle.

Experimental characterization of the optical klystron effect to measure the intrinsic energy spread of high-brightness electron beams

The intrinsic energy spread of electron beams needs to be measured to characterize and optimize high-brightness electron beam sources such as those driving x-ray free-electron lasers (FELs). We demonstrate the use of the optical klystron effect as a precise and high-resolution method to measure the electron beam energy spread. The optical klystron setup consists of undulator modules and magnetic chicanes placed between them. The energy spread is found by measuring the radiation power produced in the undulators as a function of the chicanes’ strengths. High resolution and simplicity are the advantages of this approach, in contrast to the standard method, which measures the longitudinal phase space of the electron beam with a transverse deflector. The demonstration was performed at Athos, the soft x-ray FEL beamline of SwissFEL, for which we measured energy spreads below 1 MeV at a central beam energy of 3.4 GeV. We have verified the consistency of the method for different parameters (radiation wavelengths, undulator polarization configurations, and electron bunch durations) and we have benchmarked it against the standard measurement approach using a transverse deflector. Our results confirm the optical klystron as a valid approach to measure the electron beam energy spread. The method can be especially useful to reconstruct low energy spread values, where the conventional approach may be resolution limited, such as in ultra high-brightness radiofrequency photoinjectors or plasma sources, or when transverse deflectors are not available. Published by the American Physical Society 2024

Divergence angle consideration in energy spread measurement for high-quality relativistic electron beam in laser wakefield acceleration

The thorough exploration of the transverse quality represented by divergence angle has been lacking yet in the energy spread measurement of the relativistic electron beam for laser wakefield acceleration (LWFA). In this work, we fill this gap by numerical simulations based on the experimental data, which indicate that in a C-shape magnet, magnetic field possesses the beam focusing effect, considering that the divergence angle will result in an increase in the full width at half maxima (FWHM) of the electron density distribution in a uniformly isotropic manner, while the length-to-width ratio decreases. This indicates that the energy spread obtained from the electron deflection distance is smaller than the actual value, regardless of the divergence angle. A promising and efficient way to accurately correct the value is presented by considering the divergence angle (for instance, for an electron beam with a length-to-width ratio of 1.12, the energy spread correct from 1.2% to 1.5%), providing a reference for developing the high-quality electron beam source.

SPECIFIC FEATURES OF THE CURRENT FLOW THROUGH AN ALUMINA-BASED METAL-CERAMIC COMPOSITE DURING ELECTRON BEAM IRRADIATION IN THE FOREVACUUM PRESSURE RANGE

We describe some specific features of the current passage through an Al<sub>2</sub>O<sub>3</sub>-Ti metal-ceramic composite sample during irradiation by a forevacuum-pressure plasma-cathode electron beam source. The composition ratio of the composite was 90% Al<sub>2</sub>O<sub>3</sub> and 10% Ti by weight. It is shown that during electron-beam irradiation, the magnitude and direction of the current through the sample depend on the temperature as well as on the sintering time at given temperature. The absolute value of the recorded current can reach 15 mA for an electron-beam current of 60 mA and electron energy of 10 keV. The dependence of the current is caused by redistribution of titanium over the depth of the sintered composite during heating, and provides a means for forming gradient metal-ceramic materials with variable content of components over the depth.

Influence of Gas Pressure and Accelerating Gap Length on the Emission Characteristics of Pulsed Forevacuum Plasma Electron Beam Sources

Influence of Gas Pressure and Accelerating Gap Length on the Emission Characteristics of Pulsed Forevacuum Plasma Electron Beam Sources

ELECTRON-BEAM SINTERING OF ZIRCONIUM DIOXIDE/TITANIUM CERAMICS FOR MICROELECTRONICS PRODUCTS

Zirconium dioxide (ZrO<sub>2</sub>) has excellent physical, chemical, and mechanical properties. These properties make it an excellent material for composite ceramics. High values of dielectric permittivity, mechanical resistance, and high radiation resistance allow it to be used to protect integrated circuits (ICs) from external influences. In this study, we fabricated ZrO<sub>2</sub>/titanium (Ti) ceramic composites by employing electron-beam sintering and a forevacuum-pressure plasma-cathode electron-beam source. We used a scanning electron microscopy method to study the properties of the ceramics after sintering. The results obtained showed that with an increase in the sintering temperature up to 1700°C, the Ti content in the near-surface layer of the composite decreased to almost 0. The depth of the region with low metal component content also increased with an increase in the sintering temperature and reached 2 mm in 3-mm-thick samples. This method can be used in the production of composite materials used in IC packaging.

Collinear laser spectroscopy of highly charged ions produced with an electron-beam ion source

Collinear laser spectroscopy of highly charged ions produced with an electron-beam ion source

Investigation on the properties of anodic oxides grown on aluminium-silicon alloys irradiated by pulsed electron beam

Al-Si alloys are among the most common aluminium based materials for cast products due to theirhigh strength-to-weight ratio, excellent processability and relatively low cost. The presence of Si inthe molten Al phase improves the castability and decreases the solidification shrinkage. Hard anodicoxidation is largely employed to improve their surface mechanical properties and corrosion resistance.However, the presence of high Si contents (> 3%) and the size of Si particles in the alloy makethe process challenging or even not possible. The surface pretreatment of Al-Si alloys with intensepulsed electron beams (EB) can effectively overcome the aforementioned limitations. Electron beamsources can be employed to reduce Si content and to refine and disperse Si particles, and effectivelycreate an Al substrate that is more prone to oxidization. In the present work, two electron beamunits were used, RITM-SP and SOLO, to modify the surface properties of hypoeutectic, eutectic andhypereutectic Al-Si alloys, by investigating the effect of energy density and number of pulses. Theelectron beam treated substrates were hard anodized and characterized in term of microstructure,elemental distribution, corrosion resistance and surface mechanical properties.

Numerical Simulation of an Electron Beam Source with a Plasma Cathode and Effect of Source Parameters on Electron Emission

Numerical Simulation of an Electron Beam Source with a Plasma Cathode and Effect of Source Parameters on Electron Emission

Melting Thresholds of Materials Irradiated with a Wide Class of Pulsed Electron Beams

Based on the proposed criterion of the type of heating, a classification of the sources of pulsed electron beams was carried out, both to obtain a better understanding of the nature of the thermal processes occurring under irradiation and to predict their suitability for certain applications. The melting thresholds of materials were calculated over a wide ranges of accelerating voltages and pulse durations. On the basis of calculations, a refractoriness series was proposed for metals for surface–volume pulsed heating.