Accelerator-based neutron source and its application

Tsujimoto, Kazufumi

Proceedings of Plasma Conference 2011 (PLASMA 2011) (CD-ROM), 2 Pages, 2011/11

Neutron beam is used for a wide variety of scientific and engineering research, such as materials and life science, and industrial applications. There are three kinds of neutron sources: (1) isotopic neutron source, (2) reactor sources, and (3) accelerator-based neutron sources. Recently, high intensity spallation neutron sources with high energy proton accelerator became to offer similar capabilities to research reactors, as well as a few extra features. In Japan, the JSNS (Japan Spallation Neutron Source) was constructed and operated at J-PARC (Japan Proton Accelerator Research Complex). Moreover, as future utilization of spallation neutron, research and development for accelerator-driven subcritical system have been performed.

R&D of prediction system for tritium transport in pebble bed breeder blanket

Seki, Yohji; Hirose, Takanori; Tanigawa, Hisashi; Enoeda, Mikio

Proceedings of Plasma Conference 2011 (PLASMA 2011) (CD-ROM), 2 Pages, 2011/11

Development of test blanket module (TBM) with a water cooled solid breeder is being performed as the primary candidate of ITER-TBM of Japan. Prior to the installation of each TBM, it is necessary to develop the capability of the prediction analyses of all essential functions of the blanket to validate the analyses tools by the TBM. Especially the prediction tool of tritium concentration in the blanket system is one of the most important issues to control tritium recovery. From this view point, this paper discusses the flow phenomena and the tritium transport of the helium purge gas in the pebble bed. By prediction of purge gas flow using a numerical simulation, the result indicates tritium concentration depended on the position of the breeder layer. Namely, the large concentration still remains near the wall with approaching to an outlet.

Edge Er structure in JT-60U H-mode having Type-I ELMs

Kamiya, Kensaku; Honda, Mitsuru; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka

no journal, , 

Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the Er-well region. The shear in the edge Er becomes wider in the co-NBI case, while the edge Er-well becomes deeper in the counter-NBI case.

Modeling of inception and structure formation of discharge based on percolation

Sasaki, Akira

no journal, , 

no abstracts in English

Fast electron energy transport in solid target generated by high contrast high intense laser pulse

Tanimoto, Tsuyoshi; Nishiuchi, Mamiko; Mishima, Yosuke*; Kikuyama, Kenshiro*; Morioka, Tomoya*; Morita, Kiyoshi*; Kanasaki, Masato; Pirozhkov, A. S.; Yogo, Akifumi; Ogura, Koichi; et al.

no journal, , 

Time-resolved measurement of femtosecond laser ablation process by using a soft X-ray laser pulse

Nishikino, Masaharu; Yamamoto, Minoru*; Hasegawa, Noboru; Tomita, Takuro*; Terakawa, Kota*; Minami, Yasuo*; Takei, Ryota*; Onishi, Ryo*; Ishino, Masahiko; Kaihori, Takeshi; et al.

no journal, , 

The X-ray reflective imaging using a soft X-ray laser was used to observe the early stage of the femtosecond laser ablation process on the platinum. The fluence dependence of the soft X-ray reflectivity is classified into three regions: (1) strongly excited, (2) moderately excited, and (3) weakly excited regions. In strongly excited region, the rapid reduction of the reflectivity due to the explosive evaporation in the ablation process of the material surface was observed. In the moderately excited region, the reflectivity reduction is far slower than that in the strongly excited region. The reflectivity reduction is seemed to be caused by the growth of surface roughness on the ablation front because of the formation of nano-bubbles in the irradiated material.

Development of simulator for plasma position and shape control in JT-60SA

Miyata, Yoshiaki; Suzuki, Takahiro; Fujita, Takaaki; Ide, Shunsuke; Urano, Hajime

no journal, , 

The plasma position and shape control is important issue in JT-60SA, ITER and future fusion reactor which has a small number of coils. In order to study the plasma position and shape control, we are developing a simulator which consists of an equilibrium solver and an "isoflux" controller. The controller controls poloidal field (PF) coil currents so as to keep the poloidal flux is equal at all of specified locations. The equilibrium solver identifies an equilibrium under the specified PF coil current and implements the effect of eddy current. The position and shape control has been simulated in response to prescribed change in the poloidal beta and the internal inductance due to heating.

Development of long-pulse neutral beam injectors for JT-60SA

Kojima, Atsushi; Hanada, Masaya; JT-60NBI Group

no journal, , 

30-34 MW neutral deuterium beams are injected to JT-60SA plasmas by using neutral beam injectors with 24 positive ion sources for 12 units and 2 negative ion sources for 1 unit. As for the positive NBI, 2MW, 30s injections has already achieved with temperature increase of cooling water saturated. A beam duct for Re-ionization loss is required to be cooled additionally. The existing power supplies are applicable by enhancing the heat tolerance. Long pulse injections with higher stray magnetic field than JT-60U could be carried out by masking partial apertures whose beamlets missed the beam damp. As for the negative NBI, productions of 500keV, 3A, 0.8s and 350keV, 3MW, 30s beams has been achieved so far. Recently the database for vacuum insulation has been obtained to achieve stable acceleration of 500keV beams. Long pulse production of the negative ions are planned by constructing the new test stand of the negative ion source with temperature-controlled plasma grid.

Buckling analysis of gravity support legs for JT-60SA vacuum vessel

Ejiri, Mitsuru*; Kitamura, Kazunori*; Araki, Takao*; Omori, Junji*; Asano, Shiro*; Hayakawa, Atsuro*; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira

no journal, , 

In the operation of tokamak, such loads as electromagnetic and seismic are assumed to be imposed on the vacuum vessel (VV), and not a little thermal expansion takes place when VV is baked. The gravity support leg (GS) has to support the loads described above in addition to the dead weight of VV including in-vessel components and compensate deformation. The GS is equipped with plate spring (PS) to have both stiffness and flexibility. In this study, the buckling strength of the PSs was evaluated. The effect of the initial imperfection of the PSs which is assumed to result from machining or welding process on the buckling strength was also studied. It is concluded that GS has sufficient buckling strength against assumed initial imperfections.

Improvement of edge-plasma modeling and its impact on the SONIC simulation for JT-60SA divertor

Kawashima, Hisato; Shimizu, Katsuhiro; Hoshino, Kazuo; Takizuka, Tomonori*; Sakurai, Shinji

no journal, , 

For SONIC simulation on JT-60SA divertor, the heat flux limiter is introduced in the ion parallel heat transport besides electron one. Changing the limit factor from = 0.5 to 10, density decrement and temperature increment in the edge-plasma are remarkable at = 0.5 in comparison with a case without limiter. Sensitivity on the radial particle or thermal diffusivity is surveyed with range of D = 0.11 m/s and = 0.12 m/s. Divertor heat flux increases from 7.5 to 10.5 MW/m with decrease of D. This sensitivity is stronger than that for .