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Laser-Driven Ultrashort Pulsed Electron Beam Radiation at Doses of 0.5 and 1.0 Gy Induces Apoptosis in Human Fibroblasts
摘要： Rapidly evolving laser technologies have led to the development of laser-generated particle accelerators as an alternative to conventional facilities. However, the radiobiological characteristics need to be determined to enhance their applications in biology and medicine. In this study, the radiobiological effects of ultrashort pulsed electron beam (UPEB) and X-ray radiation in human lung fibroblasts (MRC-5 cell line) exposed to doses of 0.1, 0.5, and 1 Gy are compared. The changes of γH2AX foci number as a marker of DNA double-strand breaks (DSBs) were analyzed. In addition, the micronuclei induction and cell death via apoptosis were studied. We found that the biological action of UPEB-radiation compared to X-rays was characterized by significantly slower γH2AX foci elimination (with a dose of 1 Gy) and strong apoptosis induction (with doses of 0.5 and 1.0 Gy), accompanied by a slight increase in micronuclei formation (dose of 1 Gy). Our data suggest that UPEB radiation produces more complex DNA damage than X-ray radiation, leading to cell death rather than cytogenetic disturbance.
关键词： ionizing radiation,γH2AX,apoptosis,micronuclei,ultrashort pulsed electron beam
更新于2025-09-11 14:15:04
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Metamaterials and Metasurfaces || Electron Beam-Induced Directional Terahertz Radiation from Metamaterials
摘要： We have numerically analyzed an electron beam (e-beam)-induced directional terahertz (THz) radiation from metamaterials. Here, we used metallic grating structures with graded depths, in which only one-way surface mode can be supported based on the spoof surface plasmon polariton (spoof SPP) concept and gives unique directional THz radiation. For numerical analysis, we used a simplified particle-in-cell (PIC) finite-difference time-domain (FDTD) method. First, we describe our simplified PIC-FDTD method in detail. Then, we show our results on the e-beam-induced directional THz radiation from graded grating with graded depths. By passing pulsed (bunched) e-beam along the grating surface, directional THz radiations are obtained from one side of the grating with shallower grooves. The direction of these radiations can be switched backward or forward by making the groove depth deeper or shallower. The spectra of these directional radiations are wide band and contain multiple sharp peaks. The deepest and the shallowest groove depths determine the lowest and the highest frequency of the radiation band, respectively. These unique radiation characteristics cannot be explained by the conventional Smith-Purcell radiation and should be attributed to the spoof SPP that originates from different locations on the graded grating.
关键词： graded grating,Smith-Purcell radiation,THz,particle-in-cell finite-difference time-domain,metamaterial,PIC-FDTD,electron beam,terahertz
更新于2025-09-11 14:15:04
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Electron‐Beam‐Driven III‐Nitride Plasmonic Nanolasers in the Deep‐UV and Visible Region
摘要： Plasmonic nanolasers based on wide bandgap semiconductors are presently attracting immense research interests due to the breaking in light diffraction limit and subwavelength mode operation with fast dynamics. However, these plasmonic nanolasers have so far been mostly realized in the visible light ranges, or most are still under optical excitation pumping. In this work, III-nitride-based plasmonic nanolasers emitting from the green to the deep-ultraviolet (UV) region by energetic electron beam injection are reported, and a threshold as low as 8 kW cm?2 is achieved. A fast decay time as short as 123 ps is collected, indicating a strong coupling between excitons and surface plasmon. Both the spatial and temporal coherences are observed, which provide a solid evidence for exciton-plasmon coupled polariton lasing. Consequently, the achievements in III-nitride-based plasmonic nanolaser devices represent a significant step toward practical applications for biological technology, computing systems, and on-chip optical communication.
关键词： plasmonic nanolasers,electron-beam-driven,deep-ultraviolet region,III-nitride
更新于2025-09-11 14:15:04
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Nonvacuum Surfacing of Protective Coatings Using a Low-Energy Electron Beam
摘要： The results of electron-beam surfacing in air of protective coatings by a low-energy (120 keV) electron beam produced by an electron gun with a plasma emitter are presented. The gun is mounted on an industrial robotic manipulator KUKA, which allows the electron beam to be moved to the atmosphere along a given path without electromagnetic sweep. The combined (self-propagating high-temperature synthesis and electron-beam surfacing) method for obtaining coatings from reaction mixtures of TiO2 : 2.1C and TiO2 : 0.3Cr2O3 : 3.3С is implemented using this setup. The optimum composition of the reaction mixtures and the deposition regimes are determined by thermodynamic modeling using the TERRA program. The obtained coatings with a thickness of 120–200 μ m have a microhardness of 12 GPa. The coatings and the transition layer are established to have good heat resistance up to 900°C. Noticeable changes in the weight characteristics of coatings occur at above 1000°C.
关键词： electron beam surfacing at atmospheric pressure,microhardness,plasma emitter,electron beam,differential pumping system,carbide coatings,self-propagating high-temperature synthesis (SHS),electron gun,gas discharge
更新于2025-09-10 09:29:36
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High power THz-range Wave generation based on Transformation of Plasma Waves Pumped by High-current Relativistic Electron Beam
摘要： The beam-plasma interaction system allows one to generate high-power sub-mm waves (frequency interval 0.1÷1 THz) by usage of mechanism of plasma wave transformation [1]. This way gives possibility to achieve multi megawatt power with the promptly varying frequency that can be necessary for various practical applications. The original project of a sub-mm wave based on transformation of plasma waves pumped by a kA-current relativistic electron beam is developed at the GOL-PET facility. We present novel results on the study of mechanisms of sub-mm wave emission by the processes of plasma wave transformation in electromagnetic one in case of the strong beam-plasma interaction.
关键词： sub-mm wave generation,plasma waves,beam-plasma interaction,relativistic electron beam,THz-range
更新于2025-09-10 09:29:36
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Athermal coalescence of two parallel and contacting amorphous SiOx nanowires as induced by uniform e-beam irradiation
摘要： The coalescence of two parallel and contacting amorphous SiOx nanowires (a-SiOx NWs) as induced by uniform electron beam irradiation was in-situ studied at room temperature in a transmission electron microscope. It was observed that during the irradiation the two parallel and contacting nanowires exhibited a rapid athermal coalescence at and near the contacting surface and finally evolved into a single nanowire with a bigger diameter where the atom loss during the coalescence process was not observed. Based on the atom diffusion and plastic flow driven by the nanocurature of a-SiOx NWs, and the beam-induced athermal activation induced by the electron beam, a new mechanism was proposed to elucidate the experimental phenomena.
关键词： beam-induced athermal activation,nanocurvature,welding,diffusion,electron beam irradiation
更新于2025-09-10 09:29:36
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On the possibility of the electron-beam welding of quartz glasses by a forevacuum plasma electron source
摘要： The article demonstrates a principle possibility of the electron-beam welding of high-temperature quartz glasses by a plasma electron source operating in the forevacuum range of pressure of 10-50 Pa. We studied the dependence of the composition of the gas atmosphere in the vacuum chamber on the heating temperature of the weld seam. It is shown that the optimal temperature of the weld seam for melting and minimum mass entrainment from the molten pool is 1300 to 1400 0C. We determined the welding regime for cylindrical tubes and rods that provides high seam strength, reaching 90-95% of the original strength of quartz glass.
关键词： forevacuum range of pressure,electron-beam welding,plasma electron source,quartz glass
更新于2025-09-10 09:29:36
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Charging of electron beam irradiated amorphous carbon thin films at liquid nitrogen temperature
摘要： We studied the charging behavior of an amorphous carbon thin film kept at liquid-nitrogen temperature under focused electron-beam irradiation. Negative charging of the thin film is observed. The charging is attributed to a local change in the work function of the thin film induced by electron-stimulated desorption similar to the working principle of the hole free phase plate in its Volta potential implementation at elevated temperature. The negative bias of the irradiated film arises from the electron beam induced desorption of water molecules from the carbon film surface. The lack of positive charging, which is expected for non-conductive materials, is explained by a sufficient electrical conductivity of the carbon thin film even at liquid-nitrogen temperature as proven by multi-probe scanning tunneling microscopy and spectroscopy measurements.
关键词： Thin film,Radiation damage,Phase plate,Electron-beam induced charging,Hole free phase plate,Transmission electron microscope,Volta phase plate
更新于2025-09-10 09:29:36
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From EBIC images to qualitative minority carrier diffusion length maps
摘要： A novel method is presented with the aim to perform minority carrier di?usion length map on cross-sectional samples. The method is based on one Electron-Beam Induced Current (EBIC) acquisition and on the analyze of the EBIC signal slope variation on each scanned points. This method is applied on a pinned photodiode array realized on a low doped silicon epitaxy, and the electron di?usion length map which is extracted is in good accordance with our expectation taking into account the doping distribution of the device. A TCAD simulation also con?rms quantitatively the measured di?usion length map. Advantages and drawbacks of this method are discussed in this study.
关键词： CMOS image sensors,CMOS,Scanning electron microscopy (SEM),Simulation,Electron-beam-induced current (EBIC),Deep submicron process,Solid-state image sensor,Semiconductor material measurements
更新于2025-09-10 09:29:36
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Pancharatnam–Berry Optical Elements for Spin and Orbital Angular Momentum Division Demultiplexing
摘要： A Pancharatnam–Berry optical element is designed, fabricated, and optically characterized for the demultiplexing of beams with different polarization and orbital angular momentum states at the telecom wavelength of 1310 nm. The geometric phase control is achieved by fabricating properly-oriented subwavelength gratings on a silicon substrate, inducing a spatially-variant form birefringence. The digital grating pattern is transferred to the silicon substrate with a two-step nanofabrication protocol, using inductively coupled plasma reactive ion etching to transfer the resist pattern generated with high-resolution electron beam lithography. The optical characterization of the sample confirms the expected capability to sort circularly polarized optical beams with different handedness and orbital angular momentum. Encompassing optical element design and silicon photonics, the designed silicon metasurface paves the way to innovative devices for total angular momentum mode division multiplexing with unprecedented levels of integration.
关键词： subwavelength gratings,electron beam lithography,metasurfaces,silicon,orbital angular momentum,reactive ion etching,mode division multiplexing,polarization division multiplexing,Pancharatnam–Berry optical elements
更新于2025-09-10 09:29:36