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Kawachi, Tetsuya; Hasegawa, Noboru; Iwamae, Atsushi*; Yoneda, Hitoki*
Journal of Physics; Conference Series, 548(1), p.012038_1 - 012038_7, 2014/11
Times Cited Count：0 Percentile：0.00(Physics, Applied)Polarization is a fundamental property of light, and the effective use provides us powerful tools for probing materials and for plasma diagnostics. In plasmas, alignment of emission shows the plasma anisotropy, and Zeeman splitting informs us the magnetic field strength. We took the plasma-based soft X-ray laser as an example and observed the Zeeman splitting under the external magnetic field. A grazing incidence spectrograph, HIREFS, with the resolution of 15000 was used to observe the X-ray laser line. A magnetic coil driven by an electrical pulsed power supply provided the external magnetic field of 10
35 T along the direction of the plasma column, and the left-handed and right-handed circular polarization components were obtained separately. The experimental result indicated that the magnetic field was larger by a factor of 4 than that of the applied field, which implied that the magnetic field compression occurred in the dynamics of the intense laser-plasma interaction.
Iwamae, Atsushi*; Ogawa, Hiroaki; Sugie, Tatsuo; Kusama, Yoshinori
JAEA-Research 2011-045, 11 Pages, 2012/02
JAEA-Research-2011-045.pdf:2.36MB
In order to investigate reflection properties on plasma-facing material in ITER, the bi-directional reflectance distribution function (BRDF) of a tungsten block sample has been measured. On the machining surface of the block, one-directional machining lines are engraved. Two laser diodes 
652 nm and 473 nm were used to simulate H
and H
emissions, respectively. The reflected light is affected by the machining surface. The reflected light traces a line when the incident light is injected in the perpendicular direction to the engraved line. On the other hand the reflected light traces an arc shape when the incident light is injected in the parallel direction to the engraved lines. Ray tracing simulation qualitatively explains the experimental results.
Iwamae, Atsushi; Sugie, Tatsuo; Ogawa, Hiroaki; Kusama, Yoshinori
Plasma Physics and Controlled Fusion, 53(4), p.045005_1 - 045005_17, 2011/04
Times Cited Count：5 Percentile：22.60(Physics, Fluids & Plasmas)
spectral calibration method for the impurity influx monitor (divertor) for ITER using angled physical contact fibersIwamae, Atsushi; Ogawa, Hiroaki; Sugie, Tatsuo; Kusama, Yoshinori
Review of Scientific Instruments, 82(3), p.033502_1 - 033502_4, 2011/03
Times Cited Count：3 Percentile：17.79(Instruments & Instrumentation)Shoji, Mamoru*; Masuzaki, Suguru*; Kobayashi, Masahiro*; Goto, Motoshi*; Morisaki, Tomohiro*; Yamada, Hiroshi*; Komori, Akio*; Iwamae, Atsushi; Sakaue, Atsushi*; LHD Experimental Group*
Fusion Science and Technology, 58(1), p.208 - 218, 2010/07
Times Cited Count：9 Percentile：51.99(Nuclear Science & Technology)
8 and 14 keVYanagibayashi, Jun*; Nakano, Tomohide; Iwamae, Atsushi; Kubo, Hirotaka; Hasuo, Masahiro*; Itami, Kiyoshi
Journal of Physics B; Atomic, Molecular and Optical Physics, 43(14), p.144013_1 - 144013_6, 2010/07
Times Cited Count：26 Percentile：72.14(Optics)We observe the vacuum ultraviolet spectra of highly charged tungsten ions in plasmas at electron temperatures of 8 keV and 14 keV. The observed emission lines in a wavelength range of 2.6 3.2 nm for the plasma at 8 keV are identified to be the 
transitions of 
. The observed emission lines at 2.0 nm and 2.3 nm at 14 keV are identified to be the 
transitions of 
and 
transitions of 
, respectively.
=3 levels observed on MSE spectra of LHD plasmaIwamae, Atsushi; Sakaue, Atsushi*; Atake, Makoto*; Sawada, Keiji*; Goto, Motoshi*; Morita, Shigeru*
Plasma Physics and Controlled Fusion, 51(11), p.115004_1 - 115004_15, 2009/11
Times Cited Count：6 Percentile：23.42(Physics, Fluids & Plasmas)Iwamae, Atsushi; Sugie, Tatsuo; Ogawa, Hiroaki; Kusama, Yoshinori
Plasma and Fusion Research (Internet), 4, p.042_1 - 042_11, 2009/10
Hasegawa, Noboru; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kunieda, Yuichi; Kawachi, Tetsuya; Yoneda, Hitoki*; et al.
Journal of the Optical Society of Korea, 13(1), p.60 - 64, 2009/03
Times Cited Count：5 Percentile：29.17(Optics)The precise knowledge about the spectral width of the X-ray laser line is important to generate the circularly polarized X-ray laser. There are three magnetic sub-levels at lower state of the collisional excitation X-ray laser transition of the nickel-like ion X-ray laser medium. The polarization of each transition is circular or linear. Therefore the circularly polarized X-ray laser could be extracted by the influence of the Zeeman effect if the X-ray laser medium was under the external magnetic field. The strength of the magnetic field required for the circularly polarized X-ray laser is determined by the spectral width of the X-ray laser. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example and succeeded the measurement of the spectral width of the X-ray laser.
Maehara, Tsunehiro*; Kawashima, Ayato*; Iwamae, Atsushi; Mukasa, Shinobu*; Takemori, Toshihiko*; Watanabe, Takashi*; Kurokawa, Kenya*; Toyota, Hiromichi*; Nomura, Shinfuku*
Physics of Plasmas, 16(3), p.033503_1 - 033503_5, 2009/03
Times Cited Count：13 Percentile：44.28(Physics, Fluids & Plasmas)Iwamae, Atsushi; Ogawa, Hiroaki; Sugie, Tatsuo; Kasai, Satoshi*; Kusama, Yoshinori
Proceedings of 18th International Toki Conference on Development of Physics and Technology of Stellarator/Heliotrons en route to Demo (ITC-18) (CD-ROM), p.450 - 453, 2008/12
Maehara, Tsunehiro*; Miyamoto, Ippei*; Kurokawa, Kenya*; Hashimoto, Yukio*; Iwamae, Atsushi; Kuramoto, Makoto*; Yamashita, Hiroshi*; Mukasa, Shinobu*; Toyota, Hiromichi*; Nomura, Shinfuku*; et al.
Plasma Chemistry and Plasma Processing, 28(4), p.467 - 482, 2008/08
Times Cited Count：54 Percentile：87.65(Engineering, Chemical)Kim, J.*; Kim, D. E.*; Kawachi, Tetsuya; Hasegawa, Noboru; Sukegawa, Kota*; Iwamae, Atsushi*; Fujimoto, Takashi*
Journal of the Optical Society of Korea, 7(3), p.145 - 149, 2003/09
The anistropy of electron energy distribution in oxygen plasmas produced by a high intensinty laser was investigated by using polarization spectroscopy. An ultra-short pulsed laser with a pulse duration of 66.5 fs and a power density of 1
10
W/cm
was used. At this power density and pulse duration, the plasma was generated predominantly by optical field ionization. The degree of polarization of OVI 1s2p P-1s4d D
(J=1/2-3/2 and J=3/2-5/2) transition line at 129.92 
の1s 2pP-1s4sS (J=1/2-1/2 and J=3/2-1/2) transition line at 132.26 AA was used to calibrate the sensitivity of the optical system. The dependencies of the degree of polarization on the initial gas density and on the laser polarization were investigated. When the laser polarization was changed from a linear to a circlar polarization was decreased. When the initial gas density was increased, the degree of polarization was decreased.
Kawano, Yasunori; Kondoh, Takashi; Ishikawa, Masao; Ogawa, Hiroaki; Iwamae, Atsushi; Sugie, Tatsuo; Kasai, Satoshi*; Kusama, Yoshinori; Sato, Kazuyoshi
no journal, ,
no abstracts in English
Ogawa, Hiroaki; Iwamae, Atsushi; Sugie, Tatsuo; Takeuchi, Masaki; Kusama, Yoshinori
no journal, ,
no abstracts in English
Sugie, Tatsuo; Ogawa, Hiroaki; Iwamae, Atsushi; Kawano, Yasunori; Hatae, Takaki; Kajita, Shin*; Kusama, Yoshinori
no journal, ,
Plasma facing first mirrors of ITER will experience relatively higher levels of radiation due to neutron, 
ray irradiation than in present devices. An additional potential damaging effect for the first mirrors is the formation of coatings of impurities, such as Be, W, C, etc. due to erosion and re-deposition of the materials of the first wall and the divertor. Issues of the first mirror are summarized and the total fluxes and energy distributions of deuterium, helium, carbon and deuterium molecule at the first mirror positions are estimated. Protective and mitigating measures to minimize the degradation of first mirror reflectivity are adopted in the system designs of diagnostics. However, the reflectivity may change due to the environmental effects. An in-situ and remote sensitivity calibration system withstanding in the strong radiation field has been developed. Finally, remaining issues are summarized.
Ogawa, Hiroaki; Iwamae, Atsushi; Sugie, Tatsuo; Kasai, Satoshi*; Katsunuma, Atsushi*; Hara, Hirotsugu*; Takeyama, Norihide*; Kusama, Yoshinori
no journal, ,
no abstracts in English
Sugie, Tatsuo; Ogawa, Hiroaki; Iwamae, Atsushi; Kasai, Satoshi*; Nakano, Tomohide; Kusama, Yoshinori
no journal, ,
The design of the impurity influx monitor (divertor) has been carried out to provide the measurement capability in the harsh environment. The potential damaging effects for the first mirrors mounted close to the plasma are the formations of coatings of impurities and the deposition of the dust. Mitigating measures to minimize the degradation of their performance by these effects, such as changes in the reflectivity, are adopted: for example, the plasma is viewed through a small aperture, and a shutter is inserted in front of the first mirrors. It is important to know the sensitivity of the optical systems. The in-situ calibration system using a micro retro-reflector array has been developed as a possible method. It was confirmed that the calibration system has a capability to monitor the sensitivity change of the optics for plasma measurement. Distributions of spectral line emissions have been calculated. The results will be reflected to the system design.
Kawano, Yasunori; Iwamae, Atsushi; Ogawa, Hiroaki; Sugie, Tatsuo; Hatae, Takaki; Yatsuka, Eiichi; Kondoh, Takashi; Ishikawa, Masao; Sato, Kazuyoshi; Hayashi, Toshimitsu; et al.
no journal, ,
no abstracts in English
Ogawa, Hiroaki; Iwamae, Atsushi; Sugie, Tatsuo; Kasai, Satoshi*; Kusama, Yoshinori
no journal, ,
no abstracts in English
