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Charge coupling in multi-stage laser wakefield acceleration
摘要： The multi-stage technique in the laser driven acceleration of electrons has become a critical part for full-optical jitter-free accelerators. Several independent laser drivers and shorter plasma targets allow the stable and reproducible acceleration of electron bunches (or beam) at the GeV energies with narrower energy spreads. Moreover, the charge coupling, necessary for ef?cient acceleration in the consecutive acceler-ation stages, depends collectively on the parameters of the injected electron beam, the booster stage, and the nonlinear transverse dynamics of the electron beam in the laser pulse wake. An unmatched electron beam injected in the booster stage and its nonlinear transverse evolution may result in perturbations and even a reduction of the ?eld strength in the acceleration phase of the wake?eld. Thus, the analysis and characterization of charge coupling in multi-stage laser wake?eld acceleration (LWFA) are important. Here, we investigate acceleration of an externally injected electron beam in the laser wake?eld, emulating two-stage LWFA, using fully relativistic multi-dimensional particle-in-cell simulations. We also study the underlying critical parameters that affect the ef?cient coupling and acceleration of the injected electron beam in the booster stage.
关键词： charge coupling,multi-stage,electron beam,plasma wave,laser wakefield acceleration
更新于2025-09-23 15:19:57
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Atomic resolution enabled STEM imaging of nanocrystals at cryogenic temperature
摘要： In this study, we address the problem of electron-beam induced damage on two energy-related materials: LiNi0.5Mn1.5O4 used as a cathode material for lithium-ion batteries and ZnCo1.8Ni0.2O4 used as a catalyst for oxygen evolution reaction. Both materials were found to transform from the spinel into the rocksalt phase while being imaged by high-resolution scanning transmission electron microscopy (HR-STEM) at room temperature. To mitigate the degradation, we found HR-STEM characterization at cryogenic temperature delays the critical electron dose for structural modification. We determined the native phase of materials to be spinel while the other phases observed by HR-STEM were induced by the electron-beam. From a careful analysis of the experimental data and a detailed understanding of the different degradation processes induced by an energetic electron beam, we conclude that radiolysis is the mechanism responsible for the degradation in LiNi0.5Mn1.5O4 and ZnCo1.8Ni0.2O4 nanoparticles.
关键词： LiNi0.5Mn1.5O4,ZnCo1.8Ni0.2O4,electron beam degradation,cryo-STEM
更新于2025-09-23 15:19:57
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Enhancement of the surface properties of selective laser melted maraging steel by large pulsed electron-beam irradiation
摘要： The present work aimed to decrease the surface roughness of maraging steel (MS) by selective laser melting (SLM) using large pulsed electron-beam (LPEB) irradiation as a post-treatment. The MS samples were fabricated using different combinations of laser power, scanning speed, hatch distance, and build angle. The morphological features, surface roughness, phase content, and corrosion resistance of the MS samples in their as-fabricated (ASF) state were compared after LPEB irradiation. The ASF SLM-MS samples exhibit the presence of partially melted particles that spread over the entire surface and many cracks in both the longitudinal and transverse directions. A higher arithmetical mean height (Sa: 2-17 μm), large variations in Sa measured at various locations, and a strong dependence of Sa on build angle were also observed. Post-treatment by LPEB irradiation removed the partially melted particles, while reflow of the molten mass filled the cracks and voids and facilitated the formation of a uniform surface with a bright metallic finish. This has resulted in a significant decrease in Sa (0.50-4.50 μm) and a smaller variation in Sa measured at different locations. Body-centered cubic α-martensite was the predominant phase for the ASF SLM-MS samples, along with a small fraction face-centered cubic γ-austenite phase. After LPEB irradiation, the martensite was reverted to the austenite phase. The corrosion resistance of the LPEB-irradiated samples was moderately better than that of the ASF SLM-MS samples. The uniform surface morphology, removal of partially melted particles, absence of pores and cracks, decrease in Sa, and moderate improvement in corrosion resistance suggests that LPEB irradiation can be used as a post-treatment for SLM-MS samples.
关键词： corrosion resistance,large pulse electron beam irradiation,maraging steel,Selective laser melting,surface roughness
更新于2025-09-23 15:19:57
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Impact of Bi doping on CdTe thin films: Thermal annealing evolution of physical properties for solar cell absorber layer applications
摘要： To mitigate probability of instability and device degradation associated with traditional Cu doping and to tune required band gap as well as to reduce open circuit voltage loss to solar cell device, a study on evolution to the physical properties of Bi-doped CdTe films is reported. Thin films of CdTe:Bi 2% alloy are developed employing electron-beam deposition followed by air annealing. Structural studies reveal that films have preferred crystal growth along (111) plane and with annealing, films turned out to be polycrystalline. Absorbance of films is found to be affected with annealing where 450 °C annealed films show maximum absorbance. The current-voltage measurements show linear relationship reveal to ohmic contacts between the films and transparent conducting oxide substrate and conductivity is observed to be varied with annealing. The atomic force microscopy study indicates an increase in surface roughness with annealing (except for 300 °C). Our findings warrant that the optimized physical properties of CdTe:Bi 2% films annealed at 450 °C may play important role to enhance the solar cell device performance concerned.
关键词： Bismuth doping,Absorber layer,Air-annealing,Thin films,Cadmium telluride,Electron beam evaporation
更新于2025-09-23 15:19:57
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Improving Radiation Resistance of GaInP/GaInAs/Ge Triple-Junction Solar Cells Using GaInP Back-Surface Field in the Middle Subcell
摘要： This paper studies the radiation resistance for GaInP/GaInAs/Ge triple-junction space solar cells with a GaInP back-surface ?eld (BSF) in the GaInAs middle subcell compared with those with an AlGaAs BSF. The results show that the initial electrical performance is almost the same for both of them. However, the radiation resistance of the GaInP BSF cell was improved. After irradiation by 1 MeV electron beam with a cumulative dose of 1015 e/cm2, the Jsc declined by 4.73% and 6.61% for the GaInP BSF cell and the AlGaAs BSF cell, respectively; the e?ciency degradation was 13.64% and 14.61% for the GaInP BSF cell and the AlGaAs BSF cell, respectively, leading to a reduced degradation level of 6%. The mechanism for GaInP BSF to improve the radiation resistance of GaInP/GaInAs/Ge triple-junction solar cells is also discussed in this work. Similar results were obtained when irradiation cumulative doses varied from 1 × 1014 e/cm2 to 1 × 1016 e/cm2.
关键词： back-surface ?eld,electron beam irradiation,GaInP/GaInAs/Ge triple-junction space solar cell,radiation resistance
更新于2025-09-23 15:19:57
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Optoelectronic Properties of Electron Beam-Deposited NiOx Thin Films for Solar Cell Application
摘要： The fabrication of highly efficient nickel oxide (NiOx) thin film for optoelectronic devices is a challenging task because optoelectronic properties are considerably influenced by deposition technique and film thickness. The effect of thickness on the film properties of electron beam–physical vapour-deposited NiOx thin film has been investigated in this work. The influence of post-annealing treatment on the optoelectronic properties of the film was compared with that of the as-deposited one. Optical transparency gradually decreased upon the successive increment in thickness of the as-deposited and annealed films. The surface roughness of as-deposited films increased linearly with the increase in film thickness, but this behaviour was altered in post-annealed films. Spherical grains with high packing density were observed on the as-deposited films, but the grain size was altered substantially on the post-annealed films. The annealed films presented a higher work function than their corresponding as-deposited films. This work presents important insights into the design of photovoltaic devices with an effective deposition process, including a high material utilisation.
关键词： thickness,work function,NiOx,electron beam vapour deposition,annealing,opto-electronic
更新于2025-09-23 15:19:57
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Study of multilayer polymer materials after ionization treatment
摘要： Electron-beam technologies of food products processing involves the use of modern packaging materials in form of polymer films of different composition. The objective of the research is to study the impact of accelerated electrons on the structure of the polymeric packaging materials used for storage of agricultural products. It was investigated radiation exposure on film material PE/PA (80/20) with a thickness of 80 mkm. This film used for storage of vegetables and fruits and has the necessary indicators for gas and vapor permeability. Electron beam treatment of the films was performed on a compact radiation sterilization installation with local bio-protection with electron energy of 5 MeV. A polymer films were irradiated with doses from 1 to 10 kGy. Changing the structure of the film composition was monitored by IR spectrometry. As a result of irradiation by accelerated electrons with doses up to 18 kGy is established that the polymer film is modification of the polymeric material in the form of a partial degradation with subsequent intra-molecular cross-linking. This improves the physico-mechanical properties in the transverse direction, and such film can be used for food packaging before electron-beam treatment.
关键词： electron-beam technologies,radiation exposure,IR spectrometry,accelerated electrons,polymer films
更新于2025-09-23 15:19:57
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Electron beam radiation improves bond strength of UV adhesives
摘要： State-of-the-art adhesives are often a smart solution for bonding medical technology products. Certified medical grade adhesives are biocompatible, produce permanent, reliable and durable bonds and are resistant to the standard sterilisation methods. Causing additional polymerisation, electron beam (E-beam) sterilisation even improves the adhesion coefficients.
关键词： Bonded Medical Products,UV Adhesives,Medical Technology,Sterilisation,Electron Beam Radiation
更新于2025-09-23 15:19:57
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Structure and Phase Evolution in a SiC Ceramic Surface Layer During Electron-Beam Treatment
摘要： The elemental and phase compositions and substructure changes in the surface layer of SiC ceramic irradiated by pulsed electron beams of variable intensity were investigated. The structure and phase state of the ceramic surface layer were shown to be controlled by the electron-beam parameters. The electron-beam irradiation regimes leading to nanostructure detection in the SiC-ceramic surface layer were determined.
关键词： surface layer,electron beam,polytypes,SiC ceramic
更新于2025-09-19 17:15:36
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Topological edge state laser using a photonic crystal nanocavity array
摘要： In next-generation light sources, high-brightness electron beams are used in a free-electron laser configuration to produce light for use by scientists and engineers in numerous fields of research. High-brightness beams are described for such light sources as having low transverse and longitudinal emittances, high peak currents, and low slice emittance and energy spread. The optimal generation and preservation of such high-brightness electron beams during the acceleration process and propagation to and through the photon-producing element is imperative to the quality and performance of the light source. To understand the electron beam’s phase space in the accelerating section of a next-generation light source machine, we employed radio-frequency cavities operating in a deflecting mode in conjunction with a magnetic spectrometer and imaging system for both low (250 MeV) and high (1.2 GeV) electron energies. This high-resolution, high-energy system is an essential diagnostic for the optimization and control of the electron beam in the FERMI light source generating fully transversely and longitudinally coherent light in the VUV to soft x-ray wavelength regimes. This device is located at the end of the linear accelerator in order to provide the longitudinal phase space nearest to the entrance of the photon-producing beam-lines. Here, we describe the design, fabrication, characterization, commissioning, and operational implementation of this transverse deflecting cavity structure diagnostic system for the high-energy (1.2 GeV) regime.
关键词： electron beam deflection,free-electron lasers,particle beam measurements,Electron accelerators
更新于2025-09-19 17:13:59