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The discrete element method (DEM) is commonly used to study various powders in motion during transportation, screening, mixing, etc., this requires several microscopic parameters to characterize the complex mechanical behavior of the particles. Herein, a new discrete element parameter calibration method is proposed to calibrate the ultrafine agglomerated powder (recycled polyurethane powder). Optimal Latin hypercube sampling and virtual simulation experiments were conducted using the commercial DEM software, the microscopic variables included the static friction coefficient between the particles, collision recovery coefficient, Johnson&ndash, Kendall&ndash, Roberts surface energy, static friction coefficient between the particles and wall, and collision recovery coefficient. A predictive model based on genetic-algorithm-optimized feedforward neural network (back propagation) was developed to calibrate the microscopic DEM simulation parameters. The cycle search algorithm and mean-shift cluster analysis were used to confirm the input parameters&rsquo, range by comparing the mean value of the dynamic angle of repose measured via the batch accumulation test. These parameters were verified by the baffle lifting method and the rotating drum method. This calibration method, once successfully developed, will be suitable for use in a variety of fine viscous powder dynamic flow conditions.

In the International Thermonuclear Experimental Reactor (ITER) project, the feeders are one of the most important and critical systems. To convey the power supply and the coolant for the central solenoid (CS) magnet, 6 sets of CS feeders are employed, which consist mainly of an in-cryostat feeder (ICF), a cryostat feed-through (CFT), an S-bend box (SBB), and a coil terminal box (CTB). To compensate the displacements of the internal components of the CS feeders during operation, sliding cold mass supports consisting of a sled plate, a cylindrical support, a thermal shield, and an external ring are developed. To check the strength of the developed cold mass supports of the CS3U feeder, electromagnetic analysis of the two superconducting busbars is performed by using the CATIA V5 and ANSYS codes based on parametric technology. Furthermore, the thermal-structural coupling analysis is performed based on the obtained results, except for the stress concentration, and the max. stress intensity is lower than the allowable stress of the selected material. It is found that the conceptual design of the cold mass support can satisfy the required functions under the worst case of normal working conditions. All these performed activities will provide a firm technical basis for the engineering design and development of cold mass supports.

This paper presents the evolution of the design of cold mass support for the ITER magnet feeder system. The glass fibers in the cylinder and the flanges of the normal G10 support are discontinuous in the preliminary design. The heat load of this support from the analysis is only 4.86 W. However, the mechanical test of the prototype showed that it can only endure 9 kN lateral force, which is significantly less than the required 20 kN. So, the configuration of the glass fibers in the cylinders and flanges of this G10 support are modified by changing it to a continuous and knitted type to reinforce the support, and then a new improved prototype is manufactured and tested. It could endure 15 kN lateral forces this time, but still not meet the required 20 kN. Finally, the SS316LN material is chosen for the cold mass supports. The analysis results show that it is safe under 20 kN lateral forces with the heat load increased to 14.8 W. Considering the practical application, the requirements of strength is of primary importance. So, this SS316LN cold mass support is acceptable for the ITER magnet feeder system. On the other hand, the design idea of using continuous and knitted glass fibers to reinforce the strength of a G10 support is a good reference for the case with a lower heat load and not too high Lorentz force.

The superconducting toroidal field (TF) plays an important role in a superconducting tokamak, whose power supply was developed based on the feedback control principle. In this paper, superconducting tokamaks in different countries are described, and the TF power supply of the International Thermonuclear Experimental Reactor (ITER) is taken as an example to study the current-sharing characteristics in the current-stabilized stage. Firstly, the mathematical model of the TF power supply is established, and then the 3-loop control method is put forward for achieving the stability and reliability of current-stabilization and current-sharing. Furthermore, further studies indicate that the current-sharing controller has no influence on the current-stabilized control, and current-stabilizing and current-sharing can be realized at the same time. All the work done provides valuable references for the current-sharing design of the TF power supply for a superconducting tokamak, and all these studies lay a solid foundation for developing superconducting tokamaks.

A pool cooled experimental magnet based on the copper stabilized NbTi superconducting wire was designed, fabricated and tested, in order to evaluate the engineering design of the dipole superconducting magnet for the collector ring (CR) of the facility for antiproton and ion research (FAIR) project. In this paper, the experimental setup including quench protection system was presented. Performance of the liquid helium pool cooled test was introduced. All of the results indicate both the performance of conductor and the experimental superconducting magnet under low temperature is stable, which suggests the engineering design are feasible for the formal magnet in CR of the FAIR project.