Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*
Plasma and Fusion Research (Internet), 6(Sp.1), p.2401145_1 - 2401145_4, 2011/12
Atomic processes and radiation from multiple charged ions in plasmas are of the interest in the investigation of plasma wall interaction and transport of impurity ions in the fusion devices. The emission from multiple charged ions is also investigated for the development of extreme ultra violet light (EUVL) sources at . Efficient emission through the 4d-4f + 4p-4d transition array is obtained from tin ions. An optimization of pumping conditions of laser produced plasma sources is carried out theoretically and experimentally. We also investigate an extension of the plasma light sources to short wavelength to using Gd and Tb plasmas. We discuss requirements to the atomic structure, rate coefficient and collisional radiative codes to determine ion abundance and level population as a function of plasma temperature and density, to calculate the radiation intensity as well as emission spectrum.
Uto, Hiroyasu; Tobita, Kenji; Someya, Yoji; Takase, Haruhiko; Asakura, Nobuyuki
Plasma and Fusion Research (Internet), 6, p.2405053_1 - 2405053_4, 2011/08
In this study, as an advanced option for SlimCS blanket, conceptual design study of water-cooled lithium lead (WCLL) blanket was performed. Compared with solid breeder, liquid lithium-lead (LiPb) breeder seems to have advantages of the sustainment of a design value of TBR independent of lithium burn-up and of a reduction of radioactive waste. However, in SlimCS, the net TBR supplied from WCLL blanket is not enough because the thickness of blanket in SlimCS is limited to 45 cm by conducting shell position for high beta access. Therefore, the beryllium (Be) pebble bed was adopted as additional multiplier. Considering of temperature of blanket materials, a double pipe structure was adopted. The Be pebble was separated by SiC/SiC composite tube, and was cooled by coolant on center. The local TBR of WCLL with Be blanket was similar to that of solid breeder blanket on the neutron wall load Pn = 5 MW/m. Several concepts on WCLL blanket and their engineering problems are presented.
Someya, Yoji; Tobita, Kenji; Uto, Hiroyasu; Takase, Haruhiko; Liu, C.; Asakura, Nobuyuki
Plasma and Fusion Research (Internet), 6, p.2405108_1 - 2405108_4, 2011/08
Conceptual design of an alternative tritium-breeding blanket for SlimCS has been studied. The proposed blanket concept is that LiSiO pebbles or LiO pebbles for the tritium breeding and BeTi pebbles for the neutron multiplication are mixed and these pebbles are filled in the blanket. The coolant condition was selected to be sub-critical water, whose temperature difference between inlet and outlet were 290C and 360C, respectively, and pressure was 23 MPa. When LiO pebbles were mixed with BeTi pebbles, higher TBR was obtained, being greater than 1.05 for the blanket with the thickness of 0.48 m. However, the compatibility of the blanket structural material (F82H) with the sub-critical water is a concern. As the second step, therefore, we replaced the condition by the PWR water condition of 15.5 MPa and 290-330C to improve the compatibility with F82H. In addition, the PWR water has an advantage that matured technologies in nuclear power plants will be likely to reduce development risks in fusion plant engineering. Therefore, consideration of coolant plumbing was decreased from all length in blanket. On the other hand, use of the PWR water to the blanket requires a reduction of coolant plumbing length to meet the temperature range. The proposed blanket was assessed with an ANIHEAT code, and the two cases of coolant conditions were compared.
Bierwage, A.; Todo, Yasushi*; Aiba, Nobuyuki; Shinohara, Koji; Ishikawa, Masao; Yagi, Masatoshi
Plasma and Fusion Research (Internet), 6, p.2403109_1 - 2403109_5, 2011/08
Hayashi, Nobuhiko; Honda, Mitsuru; Hoshino, Kazuo; Hamamatsu, Kiyotaka; Shimizu, Katsuhiro; Takizuka, Tomonori; Ozeki, Takahisa; Fukuyama, Atsushi*
Plasma and Fusion Research (Internet), 6(Sp.1), p.2403065_1 - 2403065_8, 2011/08
Imazawa, Ryota; Kawano, Yasunori; Ono, Takehiro; Kusama, Yoshinori
Plasma and Fusion Research (Internet), 6(Sp.1), p.2402032_1 - 2402032_5, 2011/08
This paper describes results from the first integrated analysis on the feasibility of a retro-reflector (RR) installed in the ITER vacuum vessel. We make thermal and structural analyses of passively-cooled RR and terrace retro-reflector array (TERRA) by using heat load conditions on ITER. In the case of RR, the temperature reaches over 600C, and the flatness of deformed mirror surface forming RR is approximately 80 m. Although the maximal displacement of mirror surface is large, 69% of the incident-laser power returns to a diagnostic room, disturbance of phase is and rotation angle of polarization plane is less than 0.06 . On the other hand, the temperature of TERRA is approximately 350C, and the flatness of the deformed mirror surface is less than 10 m. The flatness of the mirror surface of the deformed TERRA is much smaller than laser wavelength (118 m), but the global shape is curved to ruin the coherent phase of laser light. The curvature radius of TERRA is 21 m, and 49% of the incident-laser power returns to the diagnostic room, disturbance of phase is , and rotation angle of polarization plane is less than 0.06. Since the optimized incident angles of flat and curved TERRA are different, a real-time feedback control of the incident angle is necessary for applying TERRA to ITER poloidal polarimeter.
Mori, Masahiro; Kamada, Yutaka; Ishida, Shinichi; Barabaschi, P.*
no journal, ,
no abstracts in English
Hirota, Makoto; Aiba, Nobuyuki
no journal, ,
Excitation and suppression mechanisms of Alfvn eigenmodes (AEs) have received much attention. Recent experiments show that the energetic-particle-driven AEs further induce nonlinear phenomena such as mode-mode coupling and biharmonic resonance via the MHD nonlinearity. It is theoretically worth studying how much energy can transfer from the fundamental AEs to other modes. In this work, we have formulated a simple governing equation of weakly nonlinear perturbation based on the variational principle of the MHD Lagrangian. By substituting linear eigenfunctions into the third-order potential energy, one can discuss any coupling among three eigenmodes. This technique can apply to AEs in any geometry (including tokamaks with any aspect ratio). We perform analytical and numerical evaluation of the coupling among AEs, and discuss its dependence on the beta value, the aspect ratio and the mode numbers.
Jolliet, S.; Idomura, Yasuhiro
no journal, ,