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Journal Articles

Development of an electron gun for the ERL light source in Japan

Nishimori, Nobuyuki; Hajima, Ryoichi; Iijima, Hokuto; Nagai, Ryoji; Nishitani, Tomohiro*

Proceedings of 41st Advanced ICFA Beam Dynamics Workshop on Energy Recovery Linacs (ERL '07) (CD-ROM), p.11 - 14, 2007/05

An electron gun has been developed at Japan Atomic Energy Agency (JAEA) for the ERL light source project jointly launched by JAEA, KEK, and the Institute for Solid State Physics (ISSP) of the University of Tokyo. The electron bunch is generated from a NEA photocathode upon illumination of a drive laser pulse and is accelerated to 250keV by the DC high voltage applied between the cathode and anode. We have finished high voltage terminal test and started to assemble a preparation chamber for the photocathode. We have also measured life time and quantum efficiency of AlGaAs to find a photocathode having longer life time, higher quantum efficiency and smaller emittance than GaAs. In our preliminary test, AlGaAs has shown twice higher QE and 10 times longer life time than GaAs. In this talk, our current status of the gun development is presented.

Journal Articles

FEL oscillation with a high extraction efficiency at JAEA ERL FEL

Nishimori, Nobuyuki; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nagai, Ryoji; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.265 - 272, 2006/08

One of challenges that high power FEL oscillators with energy recovery linac (ERL) are facing is to increase the extraction FEL efficiency as high as possible. The high efficiency oscillation relaxes the total beam current needed for high power lasing and makes the FEL optical pulse length shorter, which is useful for various applications. A triple bend achromat loop with energy acceptance of 7 % has been used in an ERL FEL at JAEA. Recently we have achieved the efficiency exceeding 2 %, which accompanies large energy spread beyond the energy acceptance of the loop, by doubling the electron bunch repetition rate. The optical pulse can now interact with a fresh electron bunch every round trip, while it overlapped with an injected electron every two round trips before the doubling of the bunch repetition. This talk will summarize our recent development of a high power FEL with a high extraction efficiency at JAEA ERL FEL.

Journal Articles

Beam current doubling of JAEA ERL-FEL

Nagai, Ryoji; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nishimori, Nobuyuki; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.312 - 315, 2006/08

An energy-recovery linac (ERL) for a high-power free-electron laser (FEL) R&D program is in progress at Japan Atomic Energy Agency (JAEA). The first energy-recovery operation and FEL lasing was demonstrated in 2002 by remodeling the original superconducting linac. In the first demonstration, the accelerated beam current was same as the original linac. One of the benefits of the ERL is that the accelerating beam current can be easily increase by changing micro-pulse repetition rate without increasing the main linac RF source. After the first demonstration, the e-gun, the injector RF source, the low-level RF controller, and the operation system were improved for the beam current doubling. The doubled beam acceleration and FEL lasing have been successfully achieved with 10mA of beam current and 0.7kW of FEL power.

Journal Articles

Performance of a conventional analog $$Phi$$-A type low-level RF controller

Nagai, Ryoji; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nishimori, Nobuyuki; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.316 - 318, 2006/08

For an FEL application and an ERL light source, high-stability of accelerator RF amplitude and phase is required. A low-level RF controller (LLC) of the JAEA-ERL has been improved to ensure high-stability accelerating RF field. The LLC performance is tested for a 499.8MHz superconducting cavity and a 1300MHz copper cavity. The phase and amplitude stabilities of the 499.8MHz superconducting cavity within a 1ms macro-pulse are 0.0055deg-rms and 7.64$$times$$10$$^{-5}$$, respectively. For the 1300MHz copper cavity, pulse mode and CW mode were tested. In the case of pulse mode, the phase and amplitude stabilities are 0.011deg-rms and 7.64$$times$$10$$^{-5}$$, respectively. In the case of CW mode, the phase and amplitude stabilities are 0.011deg-rms and 6.68$$times$$10$$^{-5}$$, respectively.

Journal Articles

JAEA photocathode DC-gun for an ERL injector

Nishitani, Tomohiro; Hajima, Ryoichi; Iijima, Hokuto; Nagai, Ryoji; Sawamura, Masaru; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; Minehara, Eisuke; Tabuchi, Masao*; Noritake, Yosuke*; et al.

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.319 - 322, 2006/08

ERL light source and FEL require an electron beam of large current and small emittance. In order to realize an electron gun satisfying such requirements,we started developments of a photocathode DC-gun and a new-type NEA-photocathode. The DC-gun consists of a chamber to activate NEA-surface, a 250 keV acceleration chamber, and a mode-locked Ti:Sapphire laser. Since extreme high vacuum is essential to obtain a long-life photocathode, we adopt a load-lock system for transporting a photocathode between the chambers, each of which is equipped with an NEG pump. Up to now, we fabricated an electrodes chamber and a high voltage terminal of 250 kV and we succeeded in a 250kV high voltage test. We also have suggested a superlattice photocathode as a new-type photocathode with higher performance than an existing technology. Up to now, we fabricated photocathode samples by molecular beam epitaxy and measured a quantum efficiency after NEA-surface activation.

Journal Articles

Photocathodes for the energy recovery linacs

Rao, T.*; Burrill, A.*; Chang, X. Y.*; Smedley, J.*; Nishitani, Tomohiro; Hernandez Garcia, C.*; Poelker, M.*; Seddon, E.*; Hannon, F. E.*; Sinclair, C. K.*; et al.

Nuclear Instruments and Methods in Physics Research A, 557(1), p.124 - 130, 2006/02

 Times Cited Count:58 Percentile:96.51(Instruments & Instrumentation)

In the past few years, there has been considerable interest in using an energy recovery linac (ERL) for future light sources and high-energy nuclear physics. The electron beam requirements of the ERLs under consideration span a wide range in parameters such as current, current density, frequency, operating temperatures, accelerating gradients etc. The design of the injector, whether it is normal conducting or superconducting, DC or RF, average current, temporal profile of the electron bunch all play key role in the choice of the photocathode. In this paper, we attempt to provide an overview of the available cathode materials, the pros and cons associated with each and the electron beam parameters they can provide.

Journal Articles

Micro-pulse repetition doubling of JAEA ERL-FEL

Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Sawamura, Masaru; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Minehara, Eisuke

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.514 - 516, 2006/00

no abstracts in English

Journal Articles

Design of a load-locked gun for an ERL light source

Nagai, Ryoji; Iijima, Hokuto; Nishitani, Tomohiro; Hajima, Ryoichi; Nishimori, Nobuyuki; Sawamura, Masaru; Kikuzawa, Nobuhiro; Minehara, Eisuke

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.559 - 561, 2006/00

no abstracts in English

Journal Articles

Phase stability measurement of a conventional analog $$phi$$-A type low-level RF controller

Nagai, Ryoji; Sawamura, Masaru; Hajima, Ryoichi; Nishimori, Nobuyuki; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Minehara, Eisuke

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.838 - 840, 2006/00

no abstracts in English

Journal Articles

Development status of photocathode DC-gun for ERL light source

Iijima, Hokuto; Nishitani, Tomohiro; Nagai, Ryoji; Hajima, Ryoichi; Minehara, Eisuke

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.529 - 531, 2006/00

no abstracts in English

Journal Articles

High-brightness electron source using NEA-AlGaAs photocathode

Nishitani, Tomohiro; Tabuchi, Masao*; Noritake, Yosuke*; Hayashitani, Haruhiko*; Hajima, Ryoichi; Iijima, Hokuto; Nagai, Ryoji; Sawamura, Masaru; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; et al.

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.45 - 47, 2006/00

no abstracts in English

Journal Articles

Status of JAEA ERL (2006)

Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; Iijima, Hokuto; Nishitani, Tomohiro; Minehara, Eisuke

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.251 - 253, 2006/00

no abstracts in English

Journal Articles

Design of an injector for the ERL test facility

Hajima, Ryoichi; Nagai, Ryoji; Iijima, Hokuto; Nishitani, Tomohiro; Nishimori, Nobuyuki; Osawa, Satoshi*; Sakanaka, Shogo*; Miyajima, Tsukasa*

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.753 - 755, 2006/00

no abstracts in English

Journal Articles

Observation of CSR spectrum from JAEA-ERL

Takahashi, Toshiharu*; Minehara, Eisuke; Hajima, Ryoichi; Nishimori, Nobuyuki; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Okuda, Shuichi*

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.523 - 525, 2006/00

no abstracts in English

Journal Articles

Detuning property of the JAERI ERL-FEL superconducting linac

Sawamura, Masaru; Nagai, Ryoji; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Minehara, Eisuke

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.448 - 450, 2005/07

no abstracts in English

Journal Articles

Observation of coherent synchrotron radiation from the JAERI energy recovery linac

Takahashi, Toshiharu*; Minehara, Eisuke; Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Okuda, Shuichi*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.498 - 500, 2005/07

no abstracts in English

Journal Articles

Estimation of the e-gun timing-jitter influence in an energy-rocovery linac

Nagai, Ryoji; Sawamura, Masaru; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; Nishitani, Tomohiro; Minehara, Eisuke

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.376 - 378, 2005/07

no abstracts in English

Journal Articles

Highly polarized electrons from GaAs-GaAsP and InGaAs-AlGaAs strained-layer superlattice photocathodes

Nishitani, Tomohiro; Nakanishi, Tsutomu*; Yamamoto, Masahiro*; Okumi, Shoji*; Furuta, Fumio*; Miyamoto, Masaharu*; Kuwahara, Makoto*; Yamamoto, Naoto*; Naniwa, Kenichi*; Watanabe, Osamu*; et al.

Journal of Applied Physics, 97(9), p.094907_1 - 094907_6, 2005/05

 Times Cited Count:58 Percentile:86.41(Physics, Applied)

no abstracts in English

Journal Articles

Large-scaled non-thermal laser peeling, cutting and drilling in nuclear decommissioning industry

Minehara, Eisuke; Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; Iijima, Hokuto; Nishitani, Tomohiro; Kimura, Hideaki*; Oguri, Daiichiro*; et al.

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), 10 Pages, 2005/05

The JAERI FEL has recently discovered the new FEL lasing of 255fs ultra fast pulse, 6-9% high-efficiency, one gigawatt high peak power, a few kilowatts average power, and wide tunability of medium and far infrared wavelength regions at the same time. Using the new lasing and energy-recovery linac technology, we could extend a more powerful and more efficient free-electron laser (FEL) than 10kW and 25%, respectively, for nuclear industry, pharmacy, medical, defense, shipbuilding, semiconductor industry, chemical industries, environmental sciences, space-debris, power beaming and so on. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, we need the efficient and powerful FEL driven by the JAERI compact, stand-alone and zero boil-off super-conducting RF linac with an energy-recovery geometry. Our discussions on the FEL will cover the application of non-thermal peeling, cutting, and drilling to decommission the nuclear power plants, and to prevent stress-corrosion cracking in nuclear industry and roadmap for the industrial FELs, the JAERI compact, stand-alone and zero-boil-off cryostat concept and operational experience, the new, highly-efficient, high-power, and ultra fast pulse lasing mode, and the energy-recovery geometry.

Journal Articles

Generation of coherent synchrotron radiation from JAERI-ERL

Hajima, Ryoichi; Minehara, Eisuke; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Takahashi, Toshiharu*; Okuda, Shuichi*

Proceedings of 27th International Free Electron Laser Conference (FEL 2005) (CD-ROM), p.301 - 304, 2005/00

no abstracts in English

39 (Records 1-20 displayed on this page)