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Journal Articles

Applications of stimulated brillouin scattering phase conjugate mirror to Thomson scattering diagnostics in JT-60U and ITER

Hatae, Takaki; Naito, Osamu; Kitamura, Shigeru; Sakuma, Takeshi*; Hamano, Takashi*; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*

Journal of the Korean Physical Society, 49, p.S160 - S164, 2006/12

no abstracts in English

Journal Articles

Acceleration of high current fully stripped carbon ion beam by direct injection scheme

Kashiwagi, Hirotsugu; Fukuda, Mitsuhiro; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; et al.

Review of Scientific Instruments, 77(3), p.03B305_1 - 03B305_4, 2006/03

 Times Cited Count:12 Percentile:53.77(Instruments & Instrumentation)

Acceleration of a 17mA 100keV/u C$$^{6+}$$ ion beam has been successfully achieved with an RFQ linac by means of "Direct injection scheme". The Direct injection scheme is a new scheme for injecting an ion beam from a laser ion source to the RFQ linac without a low energy beam transport line to avoid a beam loss due to the space charge effect. The high current C$$^{6+}$$ beam is required for single turn injection to a synchrotron to reduce the size of synchrotron magnets. The high current C$$^{6+}$$ beam produced by an ion source with a Nd-YAG laser was injected to the RFQ linac by the Direct injection scheme. It has been proved experimentally that the fully-stripped carbon ion beam with a current more than 10mA can be accelerated by the RFQ linac.

Journal Articles

Design and operation of high-energy and high-average-power diode-pumped single Nd:YAG amplifier with stimulated-Brillouion-scattering phase conjugate mirror

Kiriyama, Hiromitsu; Yamakawa, Koichi; Kageyama, Nobuto*; Miyajima, Hirofumi*; Kan, Hirofumi*; Yoshida, Hidetsugu*; Nakatsuka, Masahiro*

Japanese Journal of Applied Physics, Part 1, 44(10), p.7464 - 7471, 2005/10

 Times Cited Count:2 Percentile:9.62(Physics, Applied)

no abstracts in English

Journal Articles

0.5-kHz, 5-W optical parametric oscillator pumped by the second harmonic of a Nd:YAG laser

Maruyama, Yoichiro

Optical Engineering, 44(9), p.094202_1 - 094202_3, 2005/09

 Times Cited Count:1 Percentile:7.91(Optics)

A high average power BBO optical parametric oscillator pumped by a Nd:YAG laser second harmonic is demonstrated at the pulse repetition frequency of 0.5 kHz. Average power of 5.4 W (10.8 mJ) with the energy conversion efficiency of 45% is obtained for Type-I BBO OPO. The output power still increasing and undesirarble thermal effects are not observed.

Journal Articles

Recent R&D of Thomson scattering diagnostics for JT-60U and ITER

Hatae, Takaki; Kondoh, Takashi; Naito, Osamu; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*

Proceedings of 12th International Symposium on Laser-Aided Plasma Diagnostics (LAPD-12) (CD-ROM), 6 Pages, 2005/09

no abstracts in English

Journal Articles

Acceleration of high current and highly charged carbon beam using direct injection scheme

Kashiwagi, Hirotsugu; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; Fujimoto, Tetsuya*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.182 - 184, 2005/07

The carbon beam from a Nd-YAG laser ion source was accelerated successfully by an RFQ linac using Direct injection scheme. The "Direct injection scheme" is the way to inject an ion beam to the RFQ linac without a low energy beam transport line to avoid space charge effect due to a high intensity beam from the laser ion source. About 30mA of a carbon beam was detected by a faraday cup just behind the RFQ linac.

Journal Articles

Investigation of photo neutralization efficiency of high intensity H$$^{-}$$ beam with Nd:YAG laser in J-PARC

Tomisawa, Tetsuo; Akikawa, Hisashi; Sato, Susumu; Ueno, Akira; Kondo, Yasuhiro; Oigawa, Hiroyuki; Sasa, Toshinobu; Hasegawa, Kazuo; Lee, S.*; Igarashi, Zenei*; et al.

Proceedings of 7th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators (DIPAC 2005), p.275 - 277, 2005/00

The photo neutralization method with Nd:YAG laser for negative hydrogen ions has been expected as an available candidate for the transverse beam profile measurement. The fraction of photo detached electron can also be used for charge exchange procedure to extract very low power proton beam for Transmutation Experimental Facility in J-PARC. The laser system has advantages of maintenance and radiation hardness in high intensity proton accelerators. In order to establish the low power beam extraction system and beam profile monitor, the photo neutralization efficiency must be surveyed in practical beam line with high intensity H$$^{-}$$ beam. In this paper, an experimental set-up and preliminary results of photo neutralization method for intense H$$^{-}$$ beam in J-PARC MEBT1 are described.

Journal Articles

Improvement of Thomson scattering diagnostics using stimulated-Brillouin-scattering-based phase conjugate mirrors

Hatae, Takaki; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*

Purazuma, Kaku Yugo Gakkai-Shi, 80(10), p.870 - 882, 2004/10

A high performance phase conjugate mirror by stimulated Brillouin scattering (SBS-PCM) is applied to Thomson scattering diagnostics in JT-60U for the first time. To improve the measurement performance, two developments were performed with SBS-PCM. First, we developed a new optical design to provide a double-pass scattering scheme with SBS-PCM. A laser beam passing through the plasma is reflected by the SBS-PCM, and a reflected beam returned back through the same path as coming one by the phase conjugate effect, and passed through the plasma again. The double path Thomson scattering scheme demonstrated in JT-60U plasma that a factor of 1.6 increase of the scattered light in contrast with single-pass scattering. Second, an improvement of the output power of YAG laser system using the SBS-PCM was performed. As a result, average power was increased over 8 times in contrast with conventional system, and was achieved up to 368 W (7.4 J $$times$$ 50 Hz). A multi-pass Thomson scattering scheme is also proposed based on the results of double-pass scattering.

JAEA Reports

Development of cavity length control system for high repetition rate Nd:YAG laser oscillator (Joint research)

Maruyama, Yoichiro; Kubomura, Hiroyuki*; Kasamatsu, Tadashi*; Matsuoka, Shinichi*; Nakano, Fumihiko*; Kan, Hirofumi*

JAERI-Tech 2004-056, 14 Pages, 2004/09


A high average power tunable solid state laser is pumped by the second harmonic of LD-pumped high repetition rate Nd:YAG laser consisting of a single-longitudinal-mode oscillator and amplifiers. To operate the Nd:YAG laser oscillator with a single-longitudinal-mode by injection seeding, the cavity length control is required to coincide the resonant frequency of Nd:YAG laser oscillator with the frequency of seeder. For this purpose, a cavity length control system of the Nd:YAG laser oscillator is developed and the characteristics are studied. With this system, the cavity length is controlled at the pulse repetition rate of 0.5 kHz and the single frequency operation for more than three hours is realized.

JAEA Reports

Conceptual design of cesium removal device for ITER NBI maintenance

Oka, Kiyoshi; Shibanuma, Kiyoshi

JAERI-Tech 2003-004, 57 Pages, 2003/03


Cesium is required in order to generate a stable negative ion of hydrogen in an ion source of the neutral beam injector (NBI), which is one of the plasma-heating devices for International Thermonuclear Experimental Reactor (ITER). After long time operation of NBI, the cesium deposits to the insulators supporting the electrode. Due to the deterioration of the insulation resistance, the continuous operation of the NBI will be difficult. In addition, the NBI device is activated by neutron from D-T plasma, so that a periodic removal and cleaning of the cesium on the insulators by remote handling is required. A study of the cesium removal scenario and device is therefore required considering remote handling. In this report, a cesium removal procedure and conceptual design of the cesium removal device using laser ablation technique are studied, and the feasibility of laser ablation is shown.

JAEA Reports

A High repetition rate, single-frequency Nd:YAG laser oscillator and its characteristics

Maruyama, Yoichiro; Oba, Masaki; Kato, Masaaki

JAERI-Tech 2002-004, 13 Pages, 2002/02


For the in-situ measurement of various substances in the atmosphere by using DIAL (Differential Absorption LIDAR) , a high repetition rate tunable laser is required to obtain data within a few seconds. As the pump source of the tunable laser, the performance of high repetition rate and high average power is indispensable. For the generation of high quality laser radiation, a laser oscillator with 1 kHz pulse repetition rate is made and seeded with very narrow linewidth single-longitudinal mode laser radiation from the outside of the oscillator cavity and its characteristics are studied. As the results, after the thermal equilibrium of the oscillator laser crystal, a single-longitudinal and near TEMoo transverse mode are realized at the pulse repetition rate between 0.5kHz and 1kHz. Single frequency operation is preserved by controlling the cavity length. The average output power of 3W (3mJ per pulse) is obtained. It is confirmed that this oscillator has enough performance as a oscillator of MOPA (Master Oscillator Power amplifier) system.

JAEA Reports

Four-pass quadrature arrangement for highly efficient second-harmonic generation

Kiriyama, Hiromitsu; Matsuoka, Shinichi*; Arisawa, Takashi

JAERI-Research 2001-031, 8 Pages, 2001/05


no abstracts in English

JAEA Reports

High efficiency second-harmonic generation in multi-pass quadrature arrangement

Kiriyama, Hiromitsu; Nakano, Fumihiko*; Yamakawa, Koichi

JAERI-Research 2001-030, 26 Pages, 2001/05


no abstracts in English

JAEA Reports

Demonstration of quadrature arrangement using CsLiB$$_{6}$$O$$_{10}$$ crystals

Kiriyama, Hiromitsu; Matsuoka, Shinichi*; Nakano, Fumihiko*; Yamakawa, Koichi

JAERI-Research 2001-019, 7 Pages, 2001/03


no abstracts in English

Journal Articles

Very high electron temperature diagnostics using combined ruby and YAG laser Thomson scattering systems in JT-60U

Hatae, Takaki; Naito, Osamu

Proceedings of 10th International Symposium on Laser-Aided Plasma Diagnostics, p.160 - 166, 2001/00

In recent strong electron heating experiments in JT-60U, it seems that central ${it T$_{e}$}$ rises above $$sim$$15 keV which is measured by Ruby laser and YAG laser Thomson scattering systems. However, error bars are relatively large and it is difficult to measure the very high ${it T$_{e}$}$ beyond $$sim$$15 keV with high accuracy because the electron temperature region exceeds that of the original design. To improve the measurement performance in very high ${it T$_{e}$}$, we have tried the combination of existing Ruby laser system and YAG laser system. From simulations, it was found that (1) changing the form of the spectrum with the other laser is an effective way for very high ${it T$_{e}$}$ measurement, (2) furthermore the combined system in YAG laser scattering is well optimized at ${it T$_{e}$}$ $$sim$$ 20keV and relative error is reduced significantly compared with original system.

Journal Articles

Optics developments for CPA lasers in JAERI

Sugiyama, Akira; Fukuyama, Hiroyasu*; Katsurayama, Masamichi*; Anzai, Yutaka*

Denki Gakkai Hikari, Ryoshi Debaisu Kenkyukai OQD-00-50, p.23 - 28, 2000/10

no abstracts in English

Journal Articles

Incoherent Thomson scattering diagnostics on JT-60U and JFT-2M

Hatae, Takaki; Yoshida, Hidetoshi; Yamauchi, Toshihiko; Naito, Osamu

Purazuma, Kaku Yugo Gakkai-Shi, 76(9), p.868 - 873, 2000/09

no abstracts in English

Journal Articles

Development of in-pipe access welding and cutting tool using YAG laser

Oka, Kiyoshi; Tada, Eisuke; Kimura, Seiichiro*; Ogawa, Tadashi*; Sasaki, Nami*

High-power Lasers in Manufacturing (Proceedings of SPIE Vol.3888), p.702 - 709, 1999/11

no abstracts in English

JAEA Reports

Development of pipe welding, cutting & inspection tools for the ITER blanket

Oka, Kiyoshi; *; *; *; Takahashi, Hiroyuki*; Tada, Eisuke

JAERI-Tech 99-048, 222 Pages, 1999/07


no abstracts in English

26 (Records 1-20 displayed on this page)