FEL2012 - List of Authors (Sei, N.)

Paper	Title	Page
WEPD30	Simulations of XFELO for the KEK ERL	433
	R. Hajima, N. Nishimori JAEA, Ibaraki-ken, Japan N. Nakamura, M. Shimada KEK, Ibaraki, Japan N. Sei AIST, Tsukuba, Ibaraki, Japan
	Following the recent development of high-brightness electron guns and high-reflectivity X-ray crystal optics, an FEL oscillator operated in a hard X-ray wavelength region (XFELO) has been considered as a possible extension of the 3-GeV ERL light source proposed at KEK. In order to deliver a 6-GeV electron beam to the XFELO, the ERL is operated at the energy-doubling mode with a low average current. In this paper, we present results of electron beam simulations and FEL simulations.

WEPD47	Development of Free-electron Lasers using Two "Higher Orders" with the Storage Ring NIJI-IV	476
	N. Sei, H. Ogawa, K. Yamada AIST, Tsukuba, Ibaraki, Japan
	Funding: This work was supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology of Japan. In National Institute of Advanced Industrial Science and Technology (AIST), higher harmonic oscillations of free-electron lasers (FELs) have been developed with the storage ring NIJI-IV. We have already achieved the seventh harmonic FEL at a wavelength of around 890 nm, which is the highest order in the harmonic FELs. Using another "higher order", that is, higher diffraction orders of a target wavelength of dielectric multilayer mirrors, we realized the following results: + shortening a wavelength of the FEL oscillation in the NIJI-IV IR-FEL system, + lasing on the highest order in the harmonic FEL, + discovering differences between the fundamental harmonic FEL and higher harmonic FEL, + controlling the harmonic order in the same condition of the electron beam and insertion device. In the presentation, we will report the characteristics of the FEL oscillations using the two higher orders in the NIJI-IV IR-FEL system. E-mail address: sei.n@aist.go.jp N. Sei et al., J. Phys. Soc. Jpn., 79 (2010) 093501. ** N. Sei et al., Opt. Express, 20 (2012) 308.

WEPD48	Development of Intense Terahertz-wave Coherent Synchrotron Radiations at LEBRA	480
	N. Sei, H. Ogawa AIST, Tsukuba, Ibaraki, Japan K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Tanaka LEBRA, Funabashi, Japan
	Funding: This work was supported by JSPS Grant-in-Aid for Challenging Exploratory Research 2365696. Nihon University and AIST have jointly developed intense terahertz-wave coherent synchrotron radiations at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. Because a bunch length is short and a charge is large in an electron beam of a linac to saturate free-electron laser (FEL) power, the electron beam of the linac in an FEL facility is suitable for generating intense coherent radiations generally. Therefore, we launched a development of a THz-wave source with using an upstream bending magnet located in the FEL beam line. Recently, Nihon University developed 'burst mode operation', in which two or three electron bunches were included at an interval of 22.4 or 44.8 ns [1]. The electric charge in the micropulse was high (several hundreds pC) in the burst mode, so generation and observation of the coherent synchrotron radiation became easy. We have already measured the intense THz-wave from LEBRA and confirmed it to be the coherent synchrotron radiation (CSR). It was also found that CSR might have serious influence on a high-energy electron beam. In the presentation, we will report the characteristics of the CSR at LEBRA. E-mail address: sei.n@aist.go.jp 1. K. Nakao et al., Lasing of near infrared FEL with the burst-mode beam at LEBRA, Proceedings of FEL11, Shanghai, China, (2011).

Paper

Title

Page

Simulations of XFELO for the KEK ERL

433

R. Hajima, N. Nishimori
JAEA, Ibaraki-ken, Japan
N. Nakamura, M. Shimada
KEK, Ibaraki, Japan
N. Sei
AIST, Tsukuba, Ibaraki, Japan

Following the recent development of high-brightness electron guns and high-reflectivity X-ray crystal optics, an FEL oscillator operated in a hard X-ray wavelength region (XFELO) has been considered as a possible extension of the 3-GeV ERL light source proposed at KEK. In order to deliver a 6-GeV electron beam to the XFELO, the ERL is operated at the energy-doubling mode with a low average current. In this paper, we present results of electron beam simulations and FEL simulations.

WEPD47

Development of Free-electron Lasers using Two "Higher Orders" with the Storage Ring NIJI-IV

476

N. Sei, H. Ogawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

Funding: This work was supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology of Japan.
In National Institute of Advanced Industrial Science and Technology (AIST), higher harmonic oscillations of free-electron lasers (FELs) have been developed with the storage ring NIJI-IV*. We have already achieved the seventh harmonic FEL at a wavelength of around 890 nm, which is the highest order in the harmonic FELs**. Using another "higher order", that is, higher diffraction orders of a target wavelength of dielectric multilayer mirrors, we realized the following results: + shortening a wavelength of the FEL oscillation in the NIJI-IV IR-FEL system, + lasing on the highest order in the harmonic FEL, + discovering differences between the fundamental harmonic FEL and higher harmonic FEL, + controlling the harmonic order in the same condition of the electron beam and insertion device. In the presentation, we will report the characteristics of the FEL oscillations using the two higher orders in the NIJI-IV IR-FEL system.
E-mail address: sei.n@aist.go.jp
* N. Sei et al., J. Phys. Soc. Jpn., 79 (2010) 093501.
** N. Sei et al., Opt. Express, 20 (2012) 308.

WEPD48

Development of Intense Terahertz-wave Coherent Synchrotron Radiations at LEBRA

480

N. Sei, H. Ogawa
AIST, Tsukuba, Ibaraki, Japan
K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Tanaka
LEBRA, Funabashi, Japan

Funding: This work was supported by JSPS Grant-in-Aid for Challenging Exploratory Research 2365696.
Nihon University and AIST have jointly developed intense terahertz-wave coherent synchrotron radiations at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. Because a bunch length is short and a charge is large in an electron beam of a linac to saturate free-electron laser (FEL) power, the electron beam of the linac in an FEL facility is suitable for generating intense coherent radiations generally. Therefore, we launched a development of a THz-wave source with using an upstream bending magnet located in the FEL beam line. Recently, Nihon University developed 'burst mode operation', in which two or three electron bunches were included at an interval of 22.4 or 44.8 ns [1]. The electric charge in the micropulse was high (several hundreds pC) in the burst mode, so generation and observation of the coherent synchrotron radiation became easy. We have already measured the intense THz-wave from LEBRA and confirmed it to be the coherent synchrotron radiation (CSR). It was also found that CSR might have serious influence on a high-energy electron beam. In the presentation, we will report the characteristics of the CSR at LEBRA.
E-mail address: sei.n@aist.go.jp
1. K. Nakao et al., Lasing of near infrared FEL with the burst-mode beam at LEBRA, Proceedings of FEL11, Shanghai, China, (2011).