| Paper |
Title |
Page |
| MOPPH033 |
Two-Stream Smith-Purcell Free-Electron Laser Using a Dual-Grating: Linear Analysis
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111 |
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- D. Li, K. Imasaki
ILT, Suita, Osaka
- Z. Liang, W. Liu, Z. Yang
UESTC, Chengdu, Sichuan
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We present a linear analysis of two-stream Smith-Purcell Free-Electron Laser (SP-FEL). In this system, two electron-beams with velocity separation pass a rectangular dual-grating. The dispersion relation is derived employing the linear fluid theory and the growth rate is investigated through the numerical solutions. The instability of two-stream is obtained at an optimize separation velocity, and the effects of separation velocity , distance between the dual-grating, groove-depth, groove-width, beams energy on growth rate and bandwidth are studied in detail.
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| TUPPH047 |
Absolute and Convective Instability of Smith-Purcell Free Electron Laser
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431 |
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- D. Li, K. Imasaki
ILT, Suita, Osaka
- G. S. Park
SNU, Seoul
- Z. Yang
UESTC, Chengdu, Sichuan
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Smith-Purcell free electron laser can operate on two different modes. The low-energy electron excites the absolute instability and it operates in the manner of a backward-wave oscillator, while the high-energy electron induces the convective instability and it operates like a traveling-wave tube. In this paper, we demonstrate those two instabilities using a two-dimensional particle-in-cell simulation. The simulation model supposes a rectangular grating to be driven by a continuous beam, and the radiation is in the THz regime. The beam bunching and the evolution of the radiation field are observed. The variation of the gain is reported as well.
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| TUPPH048 |
Superradiant Smith-Purcell Radiation in the Terahertz-wave Region from Bunched Electron Beams
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435 |
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- Z. Shi, Z. Liang, Z. Yang
UESTC, Chengdu, Sichuan
- K. Imasaki, D. Li
ILT, Suita, Osaka
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This paper presents a study of the characteristic of Smith-Purcell radiation (SPR) in the terahertz-wave (THz) region from bunched electron beams. The model consists of a grating with different period length and grating profile to be driven by a single electron bunch and a train of periodic bunches, respectively. The radiation efficiency and the angular distribution of SPR with various bunch distribution functions are investigated. According to the analysis, the coherent emission will occur when electron bunches are short compared with the radiation wavelength, and the coherent emission strongly depends on the longitudinal distribution of bunches. Some numerical results for the sinusoidal grating are compared with those for echellette grating .The results show that the THz radiation will be obtained using the reasonable parameters for the bunches and the grating. The results provide a basis for designing a superradiant SP free-electron laser in the THz wavelength region.
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| TUPPH049 |
Study on Superradiant Smith-Purcell Radiation
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439 |
| |
- D. Li, K. Imasaki
ILT, Suita, Osaka
- S. Amano, S. Miyamoto, T. Mochizuki
NewSUBARU/SPring-8, Laboratory of Advanced Science and Technology for Industry (LASTI), Hyogo
- G. S. Park, Z. Yang
SNU, Seoul
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A simulation of coherent and superradiant Smith-Purcell radiation is performed in GHz regime using a three-dimensional particle-in-cell code. The simulation model supposes a rectangular grating to be driven by a single electron bunch,a train of periodic bunches and a continuous beam, respectively. The true Smith-Purcell radiation is distinguished from the evanescent wave, which has an angle independent frequency lower than the minimum allowed Smith-Purcell frequency. We also find that the superradiant radiations excited by periodic bunches are emitted at higher harmonics of the bunching frequency and at the corresponding Smith-Purcell angles. The "start current" is determined as well as the distributions of the radiation intensity are presented.
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