2001 Fiscal Year Final Research Report Summary
Optimization of Electron Storage Ring for Free Electron Laser
| Project/Area Number |
10450039
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied physics, general
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| Research Institution | Tohoku University (1999-2001)
Okazaki National Research Institutes (1998) |
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Principal Investigator |
HAMA Hiroyuki Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (70198795)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Hitoshi Japan Synchrotron Radiation Research Institute, SPring-8, Head Researcher, 放射光研究所, 主幹研究員
KODA Shigeru Okazaki National Research Institutes, Institute for Molecular Science, Research Associate, 分子科学研究所, 助手 (50311189)
SHINTO Katsuhiro Tohoku University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (80322999)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Free electron laser / Electron storage ring / Longitudinal phase space / Optical klystron / Potential-well distortion / Microwave instability / Phase detection / two-color experiment |
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| Research Abstract |
1. The observed longitudinal electron distribution distorted by a potential-well distortion effect that takes account the ring impedance divided into resistive and inductive parts. The first FEL macropulse evolves on a negative momentum compaction ring is predicted to be much higher than that on conventional positive momentum compaction ring by a simulation including the potential-well distortion effect. In addition, the FEL power at a equilibrated state on the negative momentum compaction ring would reach the same level as that on the positive ring, even the microwave instability exists.
2. The FEL oscillation becomes to be unstable and the its macropulse structure is being varied when the optical resonator is slightly unstable, which was evidently observed by using a streak camera. In order to secure stable FEL oscillation, the FEL pulse and the electron bunch should be strictly kept at the best synchronism. A feedback system was developed to keep such synchronism by detecting a phase difference of those higher harmonics instead of measuring time deviation. The system worked very well and excellently stable FEL was obtained.
3. Because of stable FEL oscillation, the electron bunch lengthening due to the FEL interaction was able to be precisely observed. Although the bunch lengthening was apparently not strongly, taking the potential-well distortion effect into account, the FEL induced energy spread derived by a analysis was found to be very large. However agreement of the measured energy spread with a theoretical prediction was not perfect. Further investigation is required.
4. Optimization of the cavity mirrors was also developed. By using suitable materials for the coating, mirros with both very high refrectance and transmittance were realized. As a results, the highest record of extracted FEL power on the storage rings was achieved (>0.5 W), which is now followed by a new two-color experiment to study the mechanism of photo-dissociation of gas molecules.
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