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Magnetic field, temperature and axial strain dependencies of critical current must be defined for all strands intended for the production of ITER TF windings. Such a characterization was performed for three Russian bronze routed strands. The design features of the strands under investigation are given. The measurements of critical current was carried out in the Pacman facility at the University of Twente over a range of magnetic field from 5 to 14 T, temperature from 4.2 to 11.5 K and applied axial strain from -0.7 to +0.7%. A study on irreversibility strain limit is also performed indicating that critical current degradation starts at an intrinsic strain level above 0.5%. Along with critical current data derived from voltage-current curves, a number of voltage-temperature characteristics were measured and used for further analysis. The data obtained allow one to make calculations of ITER TF coil performance as well as analysis of short conductor sample test results.

In the framework of the ITER Qualification Tests the Russian sample RFTF2 was tested in SULTAN facility. The sample is made of two identical ITER TF-type cable-in-conduit conductor sections. Bronze route strands were used for the conductor fabrication. The main characteristics of the conductor and the strand are presented as well as the sample assembly details. The test was performed in accordance with the ITER International Organization specified program. In order to evaluate the conductor performance, the current sharing temperature was measured at specified electromagnetic load cycling steps. Few voltage-current characteristics were measured with the aim of n-value estimation. Both conductor sections of the RFTF2 sample showed identical performance: the current sharing temperature is 6.4 K, that not only satisfies, but substantially exceeds ITER requirement of 5.7 K. The tests of RFTF-2 conductor sample showed that electromagnetic cyclic load as well as warm-up had negligible effect on the conductor performance. The results of the SULTAN sample test are compared with strand performance.

An extended database of critical current densities J c(T,B) and current sharing temperatures Tcs for Nb-Ti strands was obtained in this work. This data set allows one to make a more realistic forecast of the ITER poloidal field (PF) coil critical current at temperatures above 6 K and in a magnetic field of 6 T. It is found that Jc (4.2 K, 5 T) lies in the range from 700 to 2950 A/mm2, depending on the heat treatment regimes, and that Jc(6.5 K, 6 T) is 28 to 54 A/mm2 almost regardless of the applied heat treatment, i.e. the microstructure does not significantly affect Jc(6.5 K, 6 T) under such ldquoextremerdquo conditions. It is shown, that T cs (6 T) at a current of 31.2 A, which is close to the assumed operating current for the strand in the ITER PF1&6 coils, is 6.1-6.25 K. It is shown furthermore, that the application of multiparametric functions for the description of J c(T, B) or V(I, T, B) leads to a reliable prediction of Jc(T, B) only in a temperature and field range, where experimental data points are available (extrapolations result in large deviations).

At present, electroslag technology (EST) is widely used in various branches of the metallurgical industry, such as in the production of large castings for the heavy machinery and power industry.

In spite of the different nature of high coercivity in hexaferrites (Ba, Sr, Pb) and intermetallic compounds (Sm CO5, Fe‐Nd‐B) the grain size distribution function in the powders is of a great importance for both types of sintered magnets. The conventional techniques in many cases could not provide a reliable estimate of the powders’ dispersion. The fine particles (particularly the single‐domain ones) are magnetized almost to saturation and therefore are stretched together into the flocculas. These flocculas are taken by the various methods as a large particle, i.e., the methods fail. On the contrary, the jumplike domain wall motion parameters, obtained in BN spectrum study, let us analyze the distribution function of fine Ba‐Sr hexaferrites powder particles by size. Later it was found that such dependence of the BN spectrum G(f) on the mean grain size dm is true for a wide variety of the powders whose dispersivity is far from a single‐domain one. The stable dependencies of BN parameters on a powder dispe...