Plasma and Fusion Research
Volume 6, 1201004 (2011)
Rapid Communications
- Department of Fundamental Energy Science, Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
Abstract
The non-canonical Lie perturbation method for analyzing relativistic electron beams in free electron lasers [Y. Kishimoto et al., Phys. Plasmas 2, 1316 (1995)] is extended to the case with harmonic gyro-resonance due to the coexistence of a focusing wiggler and an axial guiding field, which allow the maximum beam current to be increased. By using non-canonical guiding-center variables, we have solved the particle motion not only far from the harmonic gyro-resonance but also near the resonance. Far from the resonance, the maximum beam current is found to increase in proportion to (Bg/Bw)2 (Bw and Bg are the strength of the wiggler and guiding fields, respectively). On the other hand, near the resonance, the beam is found to be confined in a finite radial region and then transmitted because of higher order secular perturbations.
Keywords
non-canonical variable, Lie transformation, stability analysis, focusing wiggler
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References
- [1] E.T. Scharlemann, J. Appl. Phys. 58, 2154 (1985).
- [2] Y. Kishimoto, J. Phys. Soc. Jpn. 65, 3877 (1996).
- [3] K. Sakamoto, T. Kobayashi, Y. Kishimoto, S. Kawasaki, S. Musyoki, A. Watanabe, M. Takahashi, H. Ishizuka and M. Shiho, Phys. Rev. Lett. 70, 441 (1993).
- [4] Y. Kishimoto, S. Tokuda and K. Sakamoto, Phys. Plasmas 2, 1316 (1995).
- [5] J.R. Cary and R.G. Littlejohn, Ann. Phys. 151, 1 (1983).
This paper may be cited as follows:
Kenji IMADERA and Yasuaki KISHIMOTO, Plasma Fusion Res. 6, 1201004 (2011).