Development of 170 GHz/500 kW gyrotron

A development of 170GHz/500kW level gyrotron was carried out as R&D work of ITER. The oscillation mode is TE_31,8. In a short pulse experiment, the maximum power of 750kW was achieved at 85kV/40A. The efficiency was 22%. In the depressed collector operation, 500kW/36%/50ms was obtained. The maximum efficiency of 40% was obtained at P_RF=470kW whereas the power decrease by the electron trapping was observed. Pulse extension was done up to 10s at P_RF=170kW with the depressed collector operation. The power was limited by the temperature increase of the output window.     

Shock consolidation of diamond powders

Fine and coarse diamond powders were shock-compacted at peak pressures of 77, 90, and 108 GPa. The densification and consolidation mechanisms of diamond powders under shock compression were investigated. The densification behaviour of the diamond powders depended strongly on the particle size of the starting materials. Fine diamond powders were densified primarily by plastic deformation, while coarse diamond powders were densified mainly by particle fracture. The relative densities of the compacted diamond samples increased with an increase in the initial particle size of the diamond and with shock pressure. The consolidation mechanism of the diamond powders under shock compression was closely related to the densification mechanism, and depended on the initial particle size of the diamond. At a shock pressure of 90 GPa, particle sizes of 2 to 4 m grade and 10 to 20 m grade were desirable as the starting material in order to produce well-bonded diamond compacts. Diamond compacts having microhardness values over 80 GPa were obtained from 2 to 4 m grade and 10 to 20 m grade diamond powders at a shock pressure of 90 G Pa, and their relative densities were 88.5% and 91.0%, respectively.     

Acrylic nonaqueous dispersion using butylated melamine-formaldehyde resin as dispersant

A series of acrylic nonaqueous dispersions were prepared by using various kinds of butylated melamine–formaldehyde (BMF) resins as dispersant. The functional group composition of BMF to form stable dispersion was butoxy group more than 13 mol/BMF 1 mol, and methylol group ranged from 1 to 2.5 mol/BMF 1 mol. It is concluded that the anchoring of BMF to acrylic copolymer was due to the formation of covalent bond between methylol group in BMF and hydroxy group in acrylic copolymer.     

Observation of three-dimensional elemental distributions of a Si device using a 360 degrees -tilt FIB and the cold field-emission STEM system

A technique for preparation of a pillar-shaped specimen and its multidirectional observation using a combination of a scanning transmission electron microscope (STEM) and a focused ion beam (FIB) instrument has been developed. The system employs an FIB/STEM compatible holder with a specially designed tilt mechanism, which allows the specimen to be tilted through 360 degrees [T. Yaguchi, M. Konno, T. Kamino, T. Hashimoto, T. Ohnishi, K. Umemura, K. Asayama, Microsc. Microanal. 9 (Suppl. 2) (2003) 118; T. Yaguchi, M. Konno, T. Kamino, T. Hashimoto, T. Ohnishi, M. Watanabe, Microsc. Microanal. 10 (Suppl. 2) (2004) 1030]. This technique was applied to obtain the three-dimensional (3D) elemental distributions around a contact plug of a Si device used in a 90-nm technology. A specimen containing only one contact plug was prepared in the shape of a pillar with a diameter of 200nm and a length of 5mum. Elemental maps were obtained from the pillar specimen using a 200-kV cold-field emission gun (FEG) STEM model HD-2300C equipped with the EDAX genesis X-ray energy-dispersive spectrometry (XEDS) system through a spectrum imaging technique. In this study, elemental distributions of minor elements with weak signals were enhanced by applying principal component analysis (PCA), which is a superior technique to extract weak signals from a large dataset. The distributions of elements, especially the metallization component Ti and minor dopant As in this particular device, were successfully extracted by PCA. Finally, the 3D elemental distributions around the contact plug could be visualized by reconstruction from the tilt series of maps.     

Homo- and copolymerizations of 3-(N-carbazolyl)-1-propyne and its homologues by Mo and W catalysts

Summary 3-(N-Carbazolyl)-1-propyne polymerized with MoCl₅- and WCl₆-based catalysts to produce a polymer in high yields. The MoCl₅ and MoCl₅-n-Bu₄Sn catalysts were the most effective (the systems solidified immediately after initiation of polymerization with these catalysts). The product polymer was a yellow solid insoluble in any solvent. Copolymerization of the present monomer with tert-butylacetylene by MoCl₅-n-Bu₄Sn produced a copolymer; it had a high molecular weight (M _w 350,000), completely dissolved in toluene, CHCl₃ etc, and formed a free-standing film by solution casting. -N-Carbazolyl-1-hexyne and-1-octyne produced toluene-insoluble polymers with WCl₆-Ph₄Sn.     

Design methodology of magnetic fields and structures for magneto-mechanical resonator based on topology optimization

Magneto-mechanical resonators—magnetically-driven vibration devices—are used in many mechanical and electrical devices. We develop topology optimization (TO) to configure the magnetic fields of such resonators to enable large vibrations under specified current input to be attained. A dynamic magneto-mechanical analysis in the frequency domain is considered where we introduce the surface magnetic force calculated from the Maxwell stress tensor. The optimization problem is then formulated involving specifically the maximization of the dynamic compliance. This formulation is implemented using the solid-isotropic-material-with-penalization method for TO by taking into account the relative permeability, Young’s modulus, and the mass density of the magnetic material as functions of the density function. Through the 2D numerical studies, we confirm that this TO method works well in designing magnetic field patterns and providing matching between the external current frequency and eigenfrequency of the vibrating structure.     

Delignification kinetics of empty fruit bunch (EFB): a sustainable and green pretreatment approach using malic acid-based solvents

Recently, the development of efficient and environmentally benign solvents has received great attention to replace current harsh organic solvents. In this context, low-transition-temperature mixtures (LTTMs) have emerged as favorable green solvents for biomass delignification. Palm oil biomass, empty fruit bunch (EFB) was pretreated with commercial l-malic acid and microwave hydrothermally extracted cactus malic acid-derived LTTMs at 60, 80, and 100 °C. The LTTMs applied in this study were derived from malic acid–choline chloride–water and malic acid–monosodium glutamate–water with a molar ratio of 2:4:2 and 3:1:5, respectively. Three first-order reactions were used to express the delignification kinetic model of EFB. The first term was based on the initial stage and assigned as infinite due to the fast rate of delignification which could not be detected. The second and third terms were proportional to bulk and residual delignification stages. A good agreement was obtained between the kinetic model and the experimental data obtained in this study with R²?≥?0.91. The activation energies for the delignification reactions using l-malic acid and cactus malic acid-based LTTMs in the bulk and residual stages were approximated as 36–56 and 19–26 kJ/mol and 34–90 and 47–87 kJ/mol, respectively.     

Solar or surplus heat-driven actuators using metal hydride alloys

A metal hydride (MH) actuator provides mechanical work by applying the hydrogen pressure transition that originates from the reversible reaction of the MH alloy as it absorbs and desorbs hydrogen gas. The MH actuators that have been reported employ a Peltier element or an electrical heating resistance wire as a heat source. This paper describes the design of an MH actuator that is driven by low-quality heat sources, such as solar heat or surplus heat. A certain composition of a LaNi₅-based alloy that produces desorbing and absorbing reactions through a low-temperature difference is specified. This alloy composition can provide a large amount of hydrogen desorption using solar heat or surplus heated water and a large amount of hydrogen absorption by natural air cooling in an adequate reaction time. To improve the moving speed and to control the performance, a reciprocating air compressor that applies this solar or surplus heat-driven MH actuator is proposed. These findings support the efficacy of an MH actuator operating without electric or fossil fuel energy consumption.     

Stiffness-Damping Simultaneous Identification under Limited Observation

A more reliable and stable method, compared to the previous one developed by the present writers, of stiffness-damping simultaneous identification of shear-type building structures is proposed using stationary random records under limited observation. It is shown that when stationary random horizontal accelerations are recorded at the floors just above and below a specific story in a shear building model, the story stiffness and the damping ratio can be identified uniquely. The viscous damping coefficient and the material damping ratio can also be identified simultaneously in a numerical model structure. It is also shown that unfavorable effects by extraneous noises, including measurement noises, due to wind excitation, building facilities, and the motion of the occupants can be eliminated partially by using the present method. The accuracy of the present identification method is investigated through the actual records under limited observation in a base-isolated building.