中国物理B ›› 2014, Vol. 23 ›› Issue (2): 24102-024102.doi: 10.1088/1674-1056/23/2/024102

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Effects of self-fields on gain in two-stream free electron laser with helical wiggler and an axial guiding magnetic field

Saviz Sa, Lashani Ea, Ashkarran Ab   

  1. a Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, P. O. Box 14665-678, Iran;
    b Department of Physics, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran
  • 收稿日期:2013-03-24 修回日期:2013-05-15 出版日期:2013-12-12 发布日期:2013-12-12

Effects of self-fields on gain in two-stream free electron laser with helical wiggler and an axial guiding magnetic field

Saviz Sa, Lashani Ea, Ashkarran Ab   

  1. a Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, P. O. Box 14665-678, Iran;
    b Department of Physics, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran
  • Received:2013-03-24 Revised:2013-05-15 Online:2013-12-12 Published:2013-12-12
  • Contact: Saviz S E-mail:Shahrooz.saviz@srbiau.ac.ir
  • About author:41.60.Cr

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摘要： The theory for the two-stream free electron laser (FEL) consisting of a relativistic electron beam transporting along the axis of a helical wiggler in the presence of an axial guiding magnetic field is proposed and investigated. In the analysis, the effects of self-fields are taken into account. The electron trajectories and the small signal gain are derived. The characteristics of the linear-gain and the normalized maximum gain are studied numerically. The results show that there are seven stable groups of orbits in the presence of self-fields instead of two groups reported in the absence of the self-fields. It is also shown that the normalized gains of three groups decrease while the rest increase with the increasing of normalized cyclotron frequency Ω0. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 3. The results show that the normalized maximum gain is enhanced in comparison with that of the single stream.

Abstract: The theory for the two-stream free electron laser (FEL) consisting of a relativistic electron beam transporting along the axis of a helical wiggler in the presence of an axial guiding magnetic field is proposed and investigated. In the analysis, the effects of self-fields are taken into account. The electron trajectories and the small signal gain are derived. The characteristics of the linear-gain and the normalized maximum gain are studied numerically. The results show that there are seven stable groups of orbits in the presence of self-fields instead of two groups reported in the absence of the self-fields. It is also shown that the normalized gains of three groups decrease while the rest increase with the increasing of normalized cyclotron frequency Ω0. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 3. The results show that the normalized maximum gain is enhanced in comparison with that of the single stream.

中图分类号:  (Free-electron lasers)

  • 41.60.Cr