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Title: Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating

Abstract

A dielectric loaded rectangular grating for Smith-Purcell devices is proposed in this paper. Regarding the electron beam as a moving plasma dielectric, a three dimensional (3D) linear theory of beam-wave interaction is developed. The first and second order growth rates are calculated, which are obtained by expanding hot dispersion equation at synchronous point. The results show that the cutoff frequency is affected by grating width. The dispersion curve becomes flatter and shifts towards lower frequency by loading dielectric in grooves. The simulation results, which are obtained by a 3D particle-in-cell code, are in good agreement with theoretical calculations. Compared the first and second order growth rate, it shows that the discrepancy is large when beam parameters are selected with high values. In this case, it is necessary to apply the second order growth rate, which can accurately describe the process of beam-wave interaction.

Authors:
;  [1];  [2]; ;  [1]
  1. Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22306228
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL GROWTH; DIELECTRIC MATERIALS; DISPERSIONS; ELECTRON BEAMS; EQUATIONS; EQUIPMENT; FREE ELECTRON LASERS; INTERACTIONS; PLASMA; SIMULATION; THREE-DIMENSIONAL CALCULATIONS

Citation Formats

Cao, Miaomiao, E-mail: mona486@yeah.net, Li, Ke, E-mail: like3714@163.com, University of Chinese Academy of Sciences, School of Electronic Science and Technology, Beijing 100049, Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn, and Wang, Yong, E-mail: wangyong3845@sina.com. Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating. United States: N. p., 2014. Web. doi:10.1063/1.4894706.
Cao, Miaomiao, E-mail: mona486@yeah.net, Li, Ke, E-mail: like3714@163.com, University of Chinese Academy of Sciences, School of Electronic Science and Technology, Beijing 100049, Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn, & Wang, Yong, E-mail: wangyong3845@sina.com. Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating. United States. doi:10.1063/1.4894706.
Cao, Miaomiao, E-mail: mona486@yeah.net, Li, Ke, E-mail: like3714@163.com, University of Chinese Academy of Sciences, School of Electronic Science and Technology, Beijing 100049, Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn, and Wang, Yong, E-mail: wangyong3845@sina.com. 2014. "Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating". United States. doi:10.1063/1.4894706.
@article{osti_22306228,
title = {Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating},
author = {Cao, Miaomiao, E-mail: mona486@yeah.net and Li, Ke, E-mail: like3714@163.com and University of Chinese Academy of Sciences, School of Electronic Science and Technology, Beijing 100049 and Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn and Wang, Yong, E-mail: wangyong3845@sina.com},
abstractNote = {A dielectric loaded rectangular grating for Smith-Purcell devices is proposed in this paper. Regarding the electron beam as a moving plasma dielectric, a three dimensional (3D) linear theory of beam-wave interaction is developed. The first and second order growth rates are calculated, which are obtained by expanding hot dispersion equation at synchronous point. The results show that the cutoff frequency is affected by grating width. The dispersion curve becomes flatter and shifts towards lower frequency by loading dielectric in grooves. The simulation results, which are obtained by a 3D particle-in-cell code, are in good agreement with theoretical calculations. Compared the first and second order growth rate, it shows that the discrepancy is large when beam parameters are selected with high values. In this case, it is necessary to apply the second order growth rate, which can accurately describe the process of beam-wave interaction.},
doi = {10.1063/1.4894706},
journal = {Journal of Applied Physics},
number = 10,
volume = 116,
place = {United States},
year = 2014,
month = 9
}
  • In this paper, a dielectric-loaded grating for Smith-Purcell device is proposed. The three-dimensional (3D) analytical theory for hot dispersion relation is obtained by using field matched method, which is solved by numerical simulations. The first and second order growth rates for the proposal model are analyzed, which is obtained by expanding hot dispersion equation at the operating point. The results show that the dispersion can be effectively weakened by introducing dielectric-loaded grating, in which the cutoff frequency is affected by the grating thickness. The dispersion curve becomes flatter and shifts towards lower frequency at the optimum grating parameters. The 3Dmore » particle-in-cell (PIC) simulation is also performed and the results are in good agreement with theoretical calculations. Comparing the first order growth rate with the second one, it reveals that the discrepancy is small when electron beam parameters are selected with small values. Otherwise, the discrepancy is large and cannot be ignored. To accurately describe the process of beam-wave interaction, the second order growth rate is necessary to apply.« less
  • We present an analytic theory for the operation of a Smith-Purcell free-electron laser with side walls that includes the effects of transverse diffraction in the optical beam. We allow the width of the electron beam and the width of the grating to vary independently and require the walls to be high compared to the wavelength of the evanescent wave. The results show that the side walls change the empty-grating dispersion relation in important ways. When the separation of the walls is not too large, it is sufficient to consider only the lowest-order transverse mode of the grating. In this case,more » we obtain excellent agreement with numerical simulations and experimental results.« less
  • In this article, the principle of the FEL using the Smith-Purcell effect is discussed. The influence of using a grating with variable spacing upon radiation is studied. The calculation shows that if such a grating is adopted and its operating parameters are selected properly, the threshold value for the pumping electric current intensity is expected to decrease and the radiation power to increase.
  • In this article, the principle of the FEL using the Smith-Purcell effect is discussed. The influence of using a grating with variable spacing upon radiation is studied. The calculation shows that if such a grating is adopted and its operating parameters are selected properly, the threshold value for the pumping electric current intensity is expected to decrease and the radiation power to increase. 8 references.
  • A dielectric loaded grating (DLG) for terahertz Smith-Purcell (SP) device is proposed to enhance the radiation intensity. By using the theoretical analysis and particle-in-cell simulations, the dispersion characteristics and SP superradiant radiation are investigated. Compared with the general metal grating, the usage of DLG can improve the magnitude of electric field and, consequently, strengthen the interaction of the evanescent wave with electron beam, which can improve the growth rate, enhance the SP superradiant radiation, and lower the start current for the operation of SP free-electron laser.