Recent progress of high-power negative ion beam development for fusion plasma heating

A negative-ion-based neutral beam injector (N-NBI) has been constructed for JT-60U. The N-NBI is designed to inject 500 keV, 10 MW neutral beams using two ion sources, each producing a 500 keV, 22 A D⁻ ion beam. In the preliminary experiment using one ion source, a D⁻ ion beam of 13.5 A has been successfully accelerated with an energy of 400 keV (5.4 MW) for 0.12 s at an operating pressure of 0.22 Pa. This is the highest D⁻ beam current and power in the world. Co-extracted electron current was effectively suppressed to the ratio of Ie/I_D⁻ < 1. The highest energy beam of 460 keV, 2.4 A, 0.44 s has also been obtained. To realize 1 MeV class NBI system for ITER (International Thermonuclear Experimental Reactor), demonstration of ampere class negative ion beam acceleration up to 1 MeV is an important mile stone. To achieve the mile stone, a prototype accelerator and a 1 MV, 1 A test facility called MeV Test Facility (MTF) were constructed. Up to now, an H⁻ ion beam was accelerated up to the energy of 805 keV with an acceleration drain current of 150 mA for 1 s in a five stage electrostatic multi-aperture accelerator.     

High‐resolution solid‐state NMR study of the domain structure and molecular motion in drawn films of a vinylidene fluoride and trifluoroethylene copolymer with 73 mol % vinylidene fluoride

The heterogeneous higher order structure and molecular motion in a single crystalline film of a vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer with 73 mol % VDF was investigated with the ¹H–¹³C cross‐polarization/magic‐angle spinning NMR technique. A transient oscillation was observed in plots of the ¹³C peak intensity versus the contact time for the CH₂, CHF, and CF₂ groups. On the basis of the extended cross‐relaxation theory of spin diffusion, we determined that the oscillation behavior was caused by the TrFE‐rich segments in the chain and that the crystal consisted of VDF‐rich and TrFE‐rich domains. The former had TrFE‐rich segments in VDF and TrFE fractions of 0.24 and 0.27, respectively, and the latter had VDF‐rich segments in a VDF fraction of 0.49. The spin–lattice relaxation time T_1ρH in the rotating frame for each group was minimal in the three temperature regions of β, α_b, and α_c (↑) on heating and in the two temperature regions of α_1D and α_c (↓) on cooling. The α_c (↑) and α_c (↓) processes depended on the first‐order ferroelectric phase‐transition regions on heating and cooling, respectively. The motional modes for the other processes were confirmed by the T_1ρH minimum behavior of the VDF and TrFE groups in the TrFE‐rich domain and the VDF‐rich segments in the VDF‐rich domain. The β and α_b processes were attributed to the flip–flop motion of the TrFE‐rich segments and the competitive motion of the TrFE‐ and VDF‐rich segments in the ferroelectric phase, respectively. The α_1D process was due to the one‐dimensional diffusion motion of the conformational defects along the chain in the paraelectric phase, accompanied by the trans and gauche transformation of the VDF conformers of ttg⁺tg^? and g⁺tg^?tt. The effect of the competitive motion of the TrFE‐rich segment on the thermal stability of the VDF‐rich segment in the chain near the Curie temperature was examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1026–1037, 2002     

An injection-locked single-mode tea CO2 laser for SMM laser pumping

A D₂O laser has been developed for collective Thomson scattering measurements of ion temperature in high temperature plasmas. A pulse duration and a spectral width of a high power D₂O laser has been successfully controlled for this purpose, by using a TEA CO₂ laser injection-locked by an etalon-tuned TEA CO₂ laser as a pump source.     

Quadruple Decker [3.3][3.3][3.3]Orthocyclophane Acetal—An Orthocyclophane Ladder

Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π–π through-space interactions within the molecule.     

Computational Analysis of Solute–Solvent Coupling Magnitude in the Z/E Isomerization Reaction of Nitroazobenzene and Benzylideneanilines

The dynamic solvent effect often arises in solution reactions, where coupling between chemical reaction and solvent fluctuation plays a decisive role in the reaction kinetics. In this study, the Z/E isomerization reaction of nitoroazobenzene and benzylideneanilines in the ground state was computationally studied by molecular dynamics simulations. The non-equilibrium solvation effect was analyzed using two approaches: (1) metadynamics Gibbs energy surface exploration and (2) solvation Gibbs energy evaluation using a frozen solvation droplet model. The solute–solvent coupling parameter (C_coupled) was estimated by the ratio of the solvent fluctuation Gibbs energy over the corresponding isomerization activation Gibbs energy. The results were discussed in comparison with the ones estimated by means of the analytical models based on a reaction–diffusion equation with a sink term. The second approach using a frozen solvation droplet reached qualitative agreement with the analytical models, while the first metadynamics approach failed. This is because the second approach explicitly considers the non-equilibrium solvation in the droplet, which consists of a solute at the reactant geometry immersed in the pre-organized solvents fitted with the solute at the transition state geometry.     

Studies of poly-yne polymers containing transition metals in the main chain : VI. Synthesis of nickel-poly-yne polymers by alkynyl ligand exchange using a copper(I) catalyst.

Reactions of trans-bis(Tri-n-butlphosphine)diethynylnickel(Ia) with 1-alkynes in the presence of an amine complex of a copper(I) salt as a catalyst give quantitatively alkynyl ligand exchange products. By this method, complex(Ia) reacts with appropriate α,ω-diethynyl compounds to afford high molecular weight linear polymers in good yields. This procedure provides a convenient route to such nickel-poly-yne polymers.     

Ermittlung der Beultraglasten ausgesteifter Schalen mit Hilfe von Übertragungsmatrizen

Übersicht Bei Beultraglastsberechnungen von ausgesteiften Kreiszylinderschalen unter Axialbelastung im plastischen Bereich werden das Deformationsverfahren und das Eigenwertverfahren mit Hilfe von übertragungsmatrizen verwendet, wobei die Übertragungsmatrix im Deformationsverfahren aus der nach der Finite-Element-Methode gewonnenen Steifigkeitsmatrix hergeleitet wird. Bei gleichzeitiger Berücksichtigung der Vorverformungen und der Restspannungen bzw. bei alleiniger Berücksichtigung der Restspannungen werden Rechenergebnisse von längsausgesteiften Schalen nach beiden Verfahren vorgelegt und verglichen.

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Study of the buckling load of stiffened shells by the transfer matrix method

Summary The deformation and eigenvalue method using the transfer matrix are applied to ultimate strength analyses of axially compressed, stiffened cylindrical shells in the plastic range. The transfer matrix in the deformation method is obtained by suitable transformation of the stiffness matrix used in the finite element method, and the transfer matrix in the eigenvalue method is described by the linearized differential equation of shells. In the deformation method geometrical imperfections and residual stresses are taken into consideration, while in the eigenvalue method the former are not considered. The numerical results of stiffened shells obtained by both methods are illustrated and compared with each other.

     

Electrochemiluminescence Sensor Having a Pt Electrode Coated Doubly with Ru(bpy)32+-Modified Chitosan and Silica Gel Membranes. Influence of the Introduction of Functional Groups into the Silica Gel on the Substrate Selectivity

Considerable research efforts are being devoted toward the development of chemical sensors and biosensors based on the so卜gel technology. We have prepared an ECL-optic sensor having a Pt electrode coated doubly with a Ru(bpy)₃²⁺-modified chitosan and silica gel membrane. In the present paper we would like to report on the substrate selectivities of ECL electrode having a silica gel layers modified with amino or alkyl groups. The new ECL electrode were prepared by the same method as reported previously, except that organotrialkoxysilanes were added to the silica-sol precursor solution. Experimental results at an applied potential of 1.10 V vs. Ag/AgCI in 0.05 M phosphate buffer (pH 6.8) for a several substrates are summarized as follows.     

Practical enantioselective reduction of ketones using oxazaborolidine catalyst generated in situ from chiral lactam alcohol and borane

Reduction intermediate prepared in situ from chiral lactam alcohol 3 and borane at room temperature was found to catalyze the borane reduction of various prochiral ketones with high enantioselectivity up to 98% ee.