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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Generation of light beams by electron beam excited surface plasmons
摘要： Manipulation of Smith-Purcell radiation (SPR) by electron-bunch excitation of localized surface plasmon (LSP) of gold (Au) disc arrays on Au substrate is investigated by FDTD simulation. When the wavelength of LSP mode is within the SPR emission band, SPR is locked and enhanced at the LSP wavelength. The emission angle of LSP-locked SPR still follows the wavelength-angle relation of traditional SPR. Furthermore, both the emission wavelength and angle increase as the radius and height of Au disc increase.
关键词： FDTD simulation,Smith-Purcell radiation (SPR),localized surface plasmon (LSP)
更新于2025-09-23 15:21:21
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The coherent THz Smith-Purcell radiation from a three-dimensional open holes array structure
摘要： Coherent Smith-Purcell radiation from multiple electron beam excitation in a three-dimensional open holes array structure has been proposed. The electron beam passes through the holes, which can be coupled with each other to enhance surface wave fields, so that the multiple electron beam injection can interact with the surface wave field efficiently. And the Smith-Purcell radiation will be enhanced due to an increasement in dipole oscillations occurring when the electrons pass through the holes. Therefore, a high beam-wave interaction efficiency is yielded and very strong coherent terahertz radiation can be generated. This multi-beam system is expected to provide a favorable way to excite the coherent Smith-Purcell radiation, which would be used to generate terahertz radiation.
关键词： terahertz radiation,open holes array structure,Smith-Purcell radiation,electron beam
更新于2025-09-23 15:21:01
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Development of a Multialkali Photocathode Dc Gun for a Smith-Purcell Terahertz Free-Electron Laser
摘要： We have developed a photocathode dc gun for a compact Smith-Purcell free-electron laser in the terahertz wavelength region. The gun system consists of an alkali antimonide photocathode preparation chamber, a dc gun with a 250 kV-50 mA Cockcroft-Walton high-voltage power supply, and a downstream beamline with a water-cooled beam dump to accommodate a beam power of 5 kW. We fabricated a Cs3Sb photocathode with quantum efficiency of 5.8% at a wavelength of 532 nm and generated a 150 keV beam with current of up to 4.3 mA with a 500 mW laser. A vacuum chamber for the Smith-Purcell free-electron laser has been installed in the downstream beamline. We describe the present status of our work.
关键词： photoemission dc gun,free-electron laser,Smith-Purcell radiation
更新于2025-09-12 10:27:22
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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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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Multi-Color Coherent Smith-Purcell Radiation with Controllable Direction from 2D Rectangular Sub-Wavelength Hole Array
摘要： We proposed a multi-color Smith-Purcell radiation source with controllable emission direction by using a sheet free-electron beam to drive the two-dimensional rectangular sub-wavelength hole array. Each hole is an electromagnetic wave oscillating and radiating unit with specified frequencies. The coherent radiation is generated when the radiation from all units constructively interfere. By adjusting the arrangement of the sub-wavelength hole array, the coherent radiation direction could be steered in the three dimensional space.
关键词： terahertz source,sub-wavelength hole array,free-electron beam,Smith-Purcell radiation,coherent radiation
更新于2025-09-04 15:30:14