Kazuyoshi Satoh

Japan Atomic Energy Agency, Muramatsu, Niigata, Japan

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Publications (5)4.25 Total impact

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    ABSTRACT: To design the divertor plate for the next generation fusion machines which is subjected to high heat loads on its one side by the plasma, it is essential to evaluate performances of heat transfer efficiency. However there is little in the literature for predicting of heat transfer coefficients under such one-sided heating conditions. To establish the heat transfer correlation for water under one-sided heating conditions, the authors have performed heat transfer experiments on smooth circular and swirl tubes in the regions from non-boiling to high subcooled partial nucleate boiling. Based on the experimental results, it is confirmed that the existing heat transfer correlations can be applicable at the non-boiling region. For the subcooled partial nucleate boiling region, they cannot be available so that a new heat transfer correlation has been proposed under one-sided heating conditions.
    International Journal of Heat and Mass Transfer 09/1996; 39(14-39):3045-3055. DOI:10.1016/0017-9310(95)00344-4 · 2.38 Impact Factor
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    ABSTRACT: JAERI has been extensively developing plasma facing components for next tokomak devices. The authors have developed a saddle type divertor module which consists of saddle-shaped armor tiles brazed on metal heat sink. This paper presents the experimental and analytical results of thermal cycling experiments of the saddle type divertor module. The divertor module has unidirectional CFC armor tiles brazed on OFHC copper heat sink. A twisted tape was inserted in the cooling tube to enhance the heat transfer. In the experiments, thermal response of the divertor module was monitored by an infrared camera and thermocouples. The maximum incident heat flux was 24.5 MW/m2 for a duration of 30 s. No degradation of thermal response was observed during the experiment. As a result, the saddle type divertor module successfully endured at an incident heat flux of over 20 MW/m2 under steady state conditions for 1000 cycles.
    Journal of Nuclear Materials 09/1994; 212:1365-1369. DOI:10.1016/0022-3115(94)91052-9 · 1.87 Impact Factor
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    ABSTRACT: High heat flux experiments have been previously carried out on three kinds, namely low pressure plasma spray (LPPS), chemical vapor deposition (CVD) and conversion (CVR) methods, of B4C-overlaid CFC's using the JAERI electron beam irradiation system (JEBIS). As a result, it turned out that CVR method has the best adhesion property between B4C layer and bulk carbon. However, thicker B4C layer is necessary to use in long period as the divertor tiles of JT-60U. The purpose of this experiment is to investigate the thermal property of B4C-converted carbon based materials which have thicker B4C layer than the previous experiments. Irradiations were performed under two different heating conditions, namely in the normal condition (5-20 MW/m(exp 2), 5 s) and in the disruption conditions (1100-1600 MW/m(exp 2), 2-3 ms). The dimensions of the samples were 25 mm x 25 mm x 25 mm, and B4C-converted layers were made on the three kinds of CFC's and fifth kinds of isotropic graphites. The thickness of B4C layer was 150-1300 (mu)m. Measurements were made with respect to the weight loss, changes of the surface morphology and the surface temperature. In the normal condition, the damages such as surface melting and exfoliation were not observed on the samples which have B4C layer below 600 (mu)m in thickness. In the disruption condition, melting and exfoliation were observed on the surfaces of the samples whose substrates were PD-330S, PD-600S and HCB-5S, and melting was observed on the surfaces of the samples whose substrates were PCC-2S, MFC-1, MCI-felt, ETP-10 and STP-60. It is considered that the porous layer in the B4C layer caused the severe exfoliation from the measurement of the surface composition.
  • I. Smid · Masato Akiba · Masanori Araki · Satoshi Suzuki · Kazuyoshi Satoh
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    ABSTRACT: The properties of materials for the carbon armored ITER divertor were evaluated from literature and manufacturers' documentation. Most of these data, however, have been not known or not published yet. We have evaluated an optimum data set of the candidate materials of the ITER divertor, which were needed for finite element analyses (FEM). The materials evaluated are as follows; MFC-1, CX2002U, SEP-N112, P-130, IG-430U for the carbon based materials, and Oxygen Free Copper (OFCu), Dispersion Strengthened Copper (DSCu), TZM, W5Re and W-Cu as a heat sink material. It should be noted that W-Cu is first proposed for a heat sink application of the ITER divertor plate. The finite element analyses were performed for the residual stress induced by brazing, thermal response and thermal stresses under a uniform heat flux of 15 MW/sq m to the plasma facing surface. The stress free temperature of 750 C is assumed for the residual stress by brazing. Ten different geometries of the divertor were considered in the analyses including possible material combinations. The FEM results show that the material combinations of MFC-1 and W-30Cu or DSUc in the flat-plate geometry satisfy the presently accepted ITER requirements. The combinations of CX2002U and TZM or W5Re is considered a good choice in terms of residual and thermal stresses, whereas the surface temperature exceeds the ITER requirements.
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    ABSTRACT: It is one of the key issues for ITER to develop the divertor plate. Electron beam irradiation tests were carried out on a NET divertor mock-up using JEBIS at JAERI under a collaboration between the NET team, JAERI, and KFA Juelich. Screening tests (maximum heat flux of 23 MW/sq m) and thermal cycling tests (18 MW/sq m, 30 s, 1000 cycles) were carried out. As a result of the screening tests, the erosion caused by sublimation of C/C was observed on the surface of armor tile. No serious damage such as cracks or detachments, however, were found. As a result of the thermal cycling tests, no major damage was detected on the C/C surface. However, the cooling time constant of the divertor mock-up increased over 600 cycles. Therefore it implies that some defects would occur at the brazing interface of the divertor mock-up.