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Rapidly heating/quenching processes were used to determine stabilization and coil performance of Nb2A1 conductors.

30kA-NbTi Demo Poloidal Coil (DPC-U) exhibited instability such as the conductor quenches at 40% of the rated current which is still much smaller than the expected conductor critical current. It was found that this instability was caused by the non-uniform current distribution in the DPC-U conductor whose strands were insulated from each other. To investigate the instability of the DPC-U conductor, a stability experiment of a subsize conductor consisting of 27 strands was performed and the effect of the current imbalance on the stability was investigated. The current imbalance was forcibly established in the conductor using two current sources in this experiment. The experimental results indicate that the stability margin decreases as the current imbalance becomes larger and that the stability margin of the conductor is governed by the stability of the strand with the highest current in the conductor. Also, it is confirmed from the experimental results that the instability of DPC-U has to be attributed to the current imbalance in the conductor.

A 40-kA [Nb.sub.3]Al cable-in-conduit conductor has been developed for the toroidal field coils of fusion reactors, because [Nb.sub.3]Al has excellent mechanical performance. This conductor consists of 405 copper-stabilized multifilamentary strands inserted into a CuNi circular conduit. The [Nb.sub.3]Al strands are fabricated by the Jelly-roll process with a diameter of 1.22 mm. This conductor could be operated up to a current of 46 kA at an external field of 11.2 T. Accordingly, [Nb.sub.3]Al promises to soon become a useful superconductor for large-scale high-field applications, such as fusion machines.

Japan Atomic Energy Research Institute (JAERI) has been developing 13-T, 40-kA conductors for the ITER Central Solenoid Scalable Model Coil. The conductors are composed of high performance [(NbTi).sub.3]Sn strands and titanium conduit. In this development work, 15-km length strand fabrication from a 100-kg billet, chrome plating, cabling of 675 or 768 strands, jacketing of titanium conduit, and so on were conducted by two mass production lines. In this paper, several test results are reported such as critical current measurements of full-scale conductors and AC loss measurements of sub-scale conductors.

Experimental tests have been conducted by the Japan Atomic Energy Research Institute to characterize the performance of its 30-kA Demo Poloidal Coils. The coils, whose windings are formvar-coated niobium titanium cable-in-conduit conductors, were tested extensively to evaluate their stability margin and current distribution. The results were then used to modify their design and construct new 30-kA conductors.

Japan Atomic Energy Research Institute has a program for the development of (NbTi)3Sn conductors for the International Thermonuclear Experimental Reactor's center solenoidal coil. Its goals are to manufacture a superconducting strand with current densities in the range of 800 A/mm2 and low ac losses. Currently, their research has concentrated on quantifying the performance of conductor samples fabricated by the bronze process, niobium tube approach and the internal tin diffusion method.

The viability of using titanium (Ti) as conduit material for cable-in-conduit (CIC) conductors in fusion magnet coils was investigated. The experiment involved the bronze processing of 7-strand and 36-strand (NbTi)3Sn CIC conductors for studying the effects of conduit material and void fraction on critical current density. It compared the performance of Ti with stainless steel and copper-nickel alloy under void fractions ranging from 5% to 46%.

Practical superconductive (SC) wires such as the Nb3Sn and Nb3Al strands used in fusion reactors are typical composite materials consisting of brittle superconducting intermetallic compounds. Thermally induced strain is inevitably generated in the composite due to the different coefficients of thermal expansion and different moduli of elasticity among the constituent components. In order to evaluate quantitatively the thermal strain, local strain measurements during heating by means of quantum beams, and room temperature tensile tests were carried out. The stress versus strain curves of both Nb3Sn and Nb33 typical elasto-plastic behavior, which could be numerically evaluated on the basis of the rule of mixtures. The local strain exerted on SC filaments along the axial direction was compressive at room temperature and tensile at high temperatures, which is common for Nb3Sn and Nb3Al strands. Their temperature dependence was numerically evaluated by means of the iteration method. As a whole, it has been established that the temperature dependence of thermal strain can be reproduced well by the numerical calculation proposed here. It is pointed out that the thermal strain in SC filaments is affected by the creep phenomenon at high temperatures above a threshold temperature. [ABSTRACT FROM AUTHOR]

Presents the microstructural characterization of the longitudinal cross section of Nb[sub 3]Al wires fabricated by an Nb tube composite process. Observation of the Al[sub 5] superconducting compound and unreacted fibrous Nb; Average Al concentration at the Al[sub 5] grain.

This review presents a comprehensive evaluation for the manufacture of organic molecules via efficient microfluidic synthesis. Microfluidic systems provide considerably higher control over the growth, nucleation, and reaction conditions compared with traditional large-scale synthetic methods. Microfluidic synthesis has become a crucial technique for the quick, affordable, and efficient manufacture of organic and organometallic compounds with complicated characteristics and functions. Therefore, a unique, straightforward flow synthetic methodology can be developed to conduct organic syntheses and improve their efficiency.