中国物理B ›› 2011, Vol. 20 ›› Issue (9): 94103-094103.doi: 10.1088/1674-1056/20/9/094103

• CLASSICAL AREAS OF PHENOMENOLOGY • 上一篇    下一篇

Gain calculation of a free-electron laser operating with a non-uniform ion-channel guide

A. Hasanbeigi1, H. Mehdian1, S. Jafari2   

  1. (1)Department of Physics and Plasma Research Institute of Tarbiat Moallem University, 49 Dr Mofatteh Avenue, Tehran 15614, Iran; (2)Department of Physics, University of Guilan, Rasht 41335-1914, Iran
  • 收稿日期:2010-09-05 修回日期:2011-02-14 出版日期:2011-09-15 发布日期:2011-09-15

Gain calculation of a free-electron laser operating with a non-uniform ion-channel guide

A. Hasanbeigia), H. Mehdiana), and S. Jafarib)   

  1. a Department of Physics and Plasma Research Institute of Tarbiat Moallem University, 49 Dr Mofatteh Avenue, Tehran 15614, Iran; b Department of Physics, University of Guilan, Rasht 41335-1914, Iran
  • Received:2010-09-05 Revised:2011-02-14 Online:2011-09-15 Published:2011-09-15

摘要: Amplification of an electromagnetic wave by a free electron laser (FEL) with a helical wiggler and an ion channel with a periodically varying ion density is examined. The relativistic equation of motion for a single electron in the combined wiggler and the periodic ion-channel fields is solved and the classes of possible trajectories in this configuration are discussed. The gain equation for the FEL in the low-gain-per-pass limit is obtained by adding the effect of the periodic ion channel. Numerical calculation is employed to analyse the gain induced by the effects of the non-uniform ion density. The variation of gain with ion-channel density is demonstrated. It is shown that there is a gain enhancement for group I orbits in the presence of a non-uniform ion-channel but not in a uniform one. It is also shown that periodic ion-channel guiding is used to reach the maximum peak gain in a low ion-channel frequency (low ion density).

Abstract: Amplification of an electromagnetic wave by a free electron laser (FEL) with a helical wiggler and an ion channel with a periodically varying ion density is examined. The relativistic equation of motion for a single electron in the combined wiggler and the periodic ion-channel fields is solved and the classes of possible trajectories in this configuration are discussed. The gain equation for the FEL in the low-gain-per-pass limit is obtained by adding the effect of the periodic ion channel. Numerical calculation is employed to analyse the gain induced by the effects of the non-uniform ion density. The variation of gain with ion-channel density is demonstrated. It is shown that there is a gain enhancement for group I orbits in the presence of a non-uniform ion-channel but not in a uniform one. It is also shown that periodic ion-channel guiding is used to reach the maximum peak gain in a low ion-channel frequency (low ion density).

Key words: free electron laser, nonuniform ion-channel, helical wiggler

中图分类号:  (Free-electron lasers)

  • 41.60.Cr
52.59.Rz (Free-electron devices) 52.38.-r (Laser-plasma interactions)