- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Laser absorption spectroscopy studies to characterize Cs oven performances for the negative ion source SPIDER
摘要： The SPIDER H?/D? ion source is currently in operation in the Neutral Beam Test facility (NBTF) at Consorzio RFX (Padova, Italy) to prove the possibility of generating up to 40 A of negative ions, with a maximum extracted current density of 350 A/m2 (H)/285 A/m2 (D) and a fraction of co-extracted electrons not greater than 0.5 (H)/1 (D). These performances are required for the realization of the ITER Neutral Beam Injector (NBI), which should deliver 16.7 MW to the plasma by means of negative ions accelerated up to 1 MeV and neutralized before being injected into the ITER tokamak. In order to obtain such high extracted current densities and low co-extracted electron fractions it is necessary to lower the work function of the surface of the acceleration system grid facing the source; this will be accomplished by coating the surfaces with Cs, routinely evaporated by three ovens. The functionality of the ovens has been tested at the CAesium oven Test Stand (CATS), hosted at NBTF. The test stand is equipped with several diagnostics, among which a Laser Absorption Spectroscopy (LAS) diagnostic. Using a tunable laser diode, the LAS diagnostic gets the high resolution absorption spectrum of the Cs 852 nm D2 line along a line of sight to measure Cs density at ground state. The paper describes the test stand and the LAS diagnostic, together with the characterization of the ovens to be installed in SPIDER. The paper will also study the systematic density underestimation e?ect caused by Cs ground state depopulation, as a function of laser intensity and of Cs density, in the perspective of correcting the density evaluation.
关键词： Plasma diagnostics - interferometry, spectroscopy and imaging,Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS))
更新于2025-09-16 10:30:52
-
[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Regime of Multi-Stage Trapping in Free Electron Lasers
摘要： Novel schemes of a trapping regime in FELs were studied. Proof-of-principle experiments on realization of “non-resonant” trapping were performed at Ka-band. For short-wavelength FELs we describe two different ways of the use of regime of “multi-stage” trapping. First, this regime can be a way for efficiency enhancement of FELs operating in SASE regime. Second, multi-stage amplification of a single-frequency RF signal can lead to an effective cooling of the operating electron beam.
关键词： electron beam cooling,multi-stage trapping,efficiency enhancement,non-resonant trapping,FELs
更新于2025-09-16 10:30:52
-
A Complex for Diagnostics of Laser Radiation of Semiconductor Targets Excited by a High-Frequency-Modulated Electron Beam
摘要： A complex of equipment for diagnosing the parameters of laser radiation of semiconductor targets, which are excited by high-frequency-modulated electron-beam pulses, is described. The ability to control the shape and duration of laser radiation in the picosecond range via high-frequency modulation of an accelerating-voltage pulse was demonstrated experimentally. A train of laser-radiation pulses with a maximum intensity of up to 2 × 107 W/cm2 was obtained on a cadmium sulfide target (λ = 525 nm).
关键词： picosecond range,cadmium sulfide,semiconductor targets,high-frequency-modulated electron-beam pulses,laser radiation
更新于2025-09-16 10:30:52
-
Tunable plasmonic HfN nanoparticles and arrays
摘要： We present the fabrication of tunable plasmonic hafnium nitride (HfN) nanoparticles. HfN is a metallic refractory material with the potential of supporting plasmon resonances in the visible range, similar to silver and gold, but with the additional benefits of high melting point, chemical stability, and mechanical hardness. However, the preparation of HfN nanoparticles and the experimental demonstration of their plasmonic potential are still in their infancy. Here, high quality HfN thin films were fabricated, for which ellipsometry shows their plasmonic potential. From these thin films, nanorods and nanotriangles were milled using a focused ion beam and the plasmon resonances were identified using cathodoluminescence mapping. As an alternative fabrication strategy, an optimized electron-beam lithography procedure was used to prepare arrays of HfN nanoparticles, which also exhibited clear surface plasmon resonances. These results pave the way to further explore HfN nanoparticles in plasmonically-powered applications where materials robustness is essential.
关键词： electron-beam lithography,plasmonic,cathodoluminescence,nanoparticles,hafnium nitride
更新于2025-09-16 10:30:52
-
AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019 - Tomsk, Russia (1a??5 October 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019 - Surface modification of selective laser melted Ti-6Al-4V by ultrasonic impact treatment and electron beam irradiation
摘要： Changes of the surface roughness, microstructure, phase composition and microhardness of selective laser melted Ti-6Al-4V samples during electron beam irradiation and ultrasonic impact treatment were investigated by contact profilometry, optical microscopy, X-ray analysis, and hardness measurement. It was shown that electron beam irradiation and ultrasonic impact treatment of the selective laser melted Ti-6Al-4V samples smooth their surface. Significant refinement of the microstructure and TiO nanoparticles formation under ultrasonic impact treatment occur causing the increase in surface microhardness. Electron beam irradiation leads to a more significant increase in both the microhardness and thickness of the melted surface layer due to martensitic transformation.
关键词： Ti-6Al-4V,surface modification,ultrasonic impact treatment,Selective laser melting,electron beam irradiation
更新于2025-09-16 10:30:52
-
Novel in-situ radiation construction of thioglycollic acid capped CdS quantum dots functionalized g-C3N4 nanohybrids with superior photocatalytic activity under visible light
摘要： A novel type of thioglycollic acid (TGA) capped CdS QDs functionalized g-C3N4 nanohybrids was prepared successfully by in-situ electron beam radiation at room temperature. When the radiation dose was chosen to be 10 kGy, the concentration of CdCl2 was 0.5 mmol/L and the optimum ratio of TGA to CdCl2 was 3 : 1 at pH = 9.0, the TGA-CdS QDs/g-C3N4 nanohydrids had the highest degradation rate at the modified TGA-CdS QDs content of 3.0 wt % and the removal rate of TGA-CdS QDs/g-C3N4 on the dye of MO was reached 94.7% in less than 20 min. The introduction of TGA-CdS QDs was confirmed successfully by a series of morphologies and structures of characterization and analysis with UV–vis, FL, Inverted-FL, DRS, FTIR, XRD, XPS, FE-SEM and HR-TEM, etc. After the introduction of TGA-CdS QDs into the surfaces of g-C3N4, the recombination of photo-generated electron-hole pairs can be significantly reduced and the photocatalytic activity and photostability can be also improved. It is favorable to enhance the photocatalytic performance for the photo-generated holes are rapidly transferred to the solution and hindered the photo-corrosion of TGA-CdS QDs.
关键词： Thioglycollic acid,Electron beam radiation,g-C3N4,Photocatalytic,Quantum dots
更新于2025-09-16 10:30:52
-
Reducing the pitting susceptibility of AISI 304 stainless steel using a hybrid treatment of high-power diode laser and large pulsed electron beam irradiation
摘要： Large pulsed electron beam (LPEB) irradiation has been widely used for surface modification of metals, alloys, polymers, and composites due to its unique interaction mechanisms with materials. The rapid melting and resolidification processes during LPEB irradiation induce phase transformation at the resolidified layer, which enables a simultaneous improvement in mechanical characteristics and chemical stability of metals. However, the generation of craters during LPEB irradiation adversely affects surface quality. It is imperative to minimize crater formation following LPEB irradiation to mitigate pitting corrosion on the surface of stainless steel (SS). In this study, a hybrid surface modification approach using a high-power diode laser (HPDL) and LPEB is proposed to reduce the crater generation during LPEB irradiation. The size and density of craters generated during LPEB irradiation were effectively reduced following the HPDL-LPEB irradiation hybrid surface treatment. The decrease in extent of crater formation and phase transformation has enabled an improvement in corrosion resistance. The ability of the resolidified layer formed after the hybrid HPDL-LPEB irradiation to form a stable passive film shifts the pitting potential from less than 0 mV/SCE (for untreated 304 SS) to more than +800 mV/SCE, which reduced the depth of corroded pits by 75%. The hybrid HPDL-LPEB irradiation decreased non-metallic inclusions, extent of crater formation and the surface roughness, and improved the pitting corrosion and general corrosion resistance.
关键词： High power diode laser,Pitting corrosion,Electron beam,Microstructure,Corrosion resistance,Stainless steels
更新于2025-09-12 10:27:22
-
A novel shaped-controlled fabrication of nanopore and its applications in quantum electronics
摘要： High-intensity (107–108 A m?2) electron beams can be used to fabricate nanoscale pores. this approach enables real-time observation of nanopore drilling and precise control of the diameter of the nanopore. nevertheless, it is not suitable for tuning the nanopore’s sidewall shape. in this study, we demonstrate the use of low-intensity electron beams to fabricate nanopores on a silicon nitride (Sinx) membrane. this technique allows the precise adjustment of the nanopore dimension and the shaping of its three-dimensional (3D) nanostructure. The 3D structures of the nanopore were evaluated by electron tomography, and series of oblique images were used in reconstructing the 3D images of nanopores using a weighted back-projection method. the sidewall shape of the nanopore was observed at different electron-beam conditions, and the formation mechanism was elucidated based on these results. the nanopore fabricated with this technique can be used as a template to develop electronics at the nanoscale based on which a quantum-dot device can be prepared with a simple evaporation process. The measured results show that the device can resolve well-defined electronic states that are characteristic for the behaviors of the quantum-dot device.
关键词： electron beam,nanopore,3D nanostructure,quantum electronics,silicon nitride membrane
更新于2025-09-12 10:27:22
-
Measurement of electron beam moire fringes with pulsed-dilation framing camera using different lasers
摘要： The electron beam moire fringe (EBMF) is generated by using a pulse-dilation framing camera. Its characteristics are measured via a nanosecond- and a femtosecond-laser. The wavefront curvature radius of the two lasers is calculated based on the measurement of the EMBF rotation angle and this result is discussed in detail. The experiments show that the EBMF rotation angles measure 31.9° and 16.6°, while the wavefront curvature radii are 12.5 mm and 21.1 mm, when the ns-laser and the fs-laser are used, respectively. This study greatly contributes in the development of EBMF-based technologies and proposes novel application directions for the use of pulse-dilation framing cameras.
关键词： Electron beam moire fringe,Ultrafast diagnostic techniques,Wavefront curvature radius,Pulse-Dilation framing camera
更新于2025-09-12 10:27:22
-
Production of highly charged ions of rare species by laser-induced desorption inside an electron beam ion trap
摘要： This paper reports on the development and testing of a novel, highly efficient technique for the injection of very rare species into electron beam ion traps (EBITs) for the production of highly charged ions (HCI). It relies on in-trap laser-induced desorption of atoms from a sample brought very close to the electron beam resulting in a very high capture efficiency in the EBIT. We have demonstrated a steady production of HCI of the stable isotope 165Ho from samples of only 1012 atoms (～300 pg) in charge states up to 45+. HCI of these species can be subsequently extracted for use in other experiments or stored in the trapping volume of the EBIT for spectroscopic measurements. The high efficiency of this technique extends the range of rare isotope HCIs available for high-precision atomic mass and spectroscopic measurements. A first application of this technique is the production of HCI of the synthetic radioisotope 163Ho for a high-precision measurement of the QEC-value of the electron capture in 163Ho within the “Electron Capture in Holmium” experiment [L. Gastaldo et al., J. Low Temp. Phys. 176, 876–884 (2014); L. Gastaldo et al., Eur. Phys. J.: Spec. Top. 226, 1623–1694 (2017)] (ECHo collaboration) ultimately leading to a measurement of the electron neutrino mass with an uncertainty on the sub electronvolt level.
关键词： high-precision atomic mass measurements,highly charged ions,spectroscopic measurements,rare isotopes,electron beam ion trap,laser-induced desorption
更新于2025-09-12 10:27:22