[en] Powder-in-Tube (PIT) processed Niobium-Tin wires are commercially manufactured for nearly three decades and have demonstrated a combination of very high current density (presently up to 2500 A mm^-2 non-Cu at 12 T and 4.2 K) with fine (35 (micro)m), well separated filaments. We review the developments that have led to the present state of the art PIT Niobium-Tin wires, discuss the wire manufacturing and A15 formation processes, and describe typical superconducting performance in relation to magnetic field and strain. We further highlight successful applications of PIT wires and conclude with an outlook on possibilities for further improvements in the performance of PIT Niobium-Tin wires.

[en] The use of HTS materials in high radiation environments requires that the superconducting properties remain constant up to a radiation high dose. BSCCO-2223 samples from two manufacturers were irradiated with 50 MeV protons at fluences of up to 5 x 10¹⁷ protons/cm². The samples lost approximately 75% of their pre-irradiation I_c. This compares with Nb₃Sn, which loses about 50% at the same displacements per atom

[en] In this paper the stability test results of the DPC-TJ coil are summarized. The DPC-TJ coil is a cable-in-conduit, forced-flow type, large superconducting coil, cooled by supercritical helium. The stability test was performed using an inductive heating method, and the dependences of the stability margins on the operating current and on the duration of heating were investigated. The relation between heating power and the take-off time, defined as the time from the start of heating until the appearance of normalcy in the conductor, was also studied. The main results are as follows: the so-called limiting currents were not obvious with the present test conditions; the influence of the duration of heating on the stability margin was small; and the heating power was inversely proportional to the square root of the take-off time, up to ∼ 20 ms. (author)

[en] The large superconducting detector magnets used for high energy physics experiments are virtually all indirectly cooled. In general, these detector magnets are not cryogenically stabilized. Therefore, there are a number of choices for cooling large indirectly cooled detector magnets. These choices include; 1) forced two-phase helium cooling driven by the helium refrigerator J-T circuit, 2) forced two-phase helium cooling driven by a helium pump, and 3) a perculation gravity feed cooling system which uses liquid helium from a large storage dewar. The choices for the cooling of a large detector magnet are illustrated by applying these concepts to a 4.2 meter diameter 0.5 tesla thin superconducting solenoid for an experiment at the Relativistic Heavy Ion Collider (RHIC). (Author)

[en] The cryostats for the superconducting resonators of the ALPI Linac have been designed to meet the requirements of both using liquid helium at 4.5 K and gaseous helium at 7 bars and 60-80 K for the thermal shield. Fourteen cryostats have already been manufactured and tested for the first phase of installation: they will house 51 resonators, of the quarter-wave type, which use lead as superconductor. An interesting solution has been adopted for the construction of the shield and the liquid helium tank. They have been constructed in 316 LN stainless steel with a double wall technique capable of working at low temperature and high pressure. (Author)

[en] The computational method is presented for the 3-dimensional nonstationary temperature fields in the UNK superconducting dipole magnet during its cooldown from 290 to 4.5 K. The method uses 1-dimensional equations for gas and a 2-dimensional heat conductivity equation for the dipole cross-section. The latter equation takes into account the interplay between the elements along the longitudinal axis. The temperature distributions were used in determining the thermomechanical stresses in the helium cryostat pipes. The computational results are compared with the experimental data. (Author)

[en] The stability of a superconducting cable, developed for operation in a 15 kA poloidal field coil of a tokamak experiment, was investigated in rapidly changing magnetic fields. The test arrangement consists of a hairpin-shaped closed loop of the cable, into which the transport current is induced inductively. A magnetic field pulse is supplied to the straight section of the sample by a capacitor discharge into a dipole magnet. The cooling conditions of the superconductor can be varied between liquid and supercritical helium in a closed volume. The results are discussed in terms of a stability model, which was successful in describing the stability of the basic strand. This model compares the energy input into the conductor during the field pulse with the transient heat removal capability of the coolant. The stability behaviour showed a distinct difference between the low and the high current range of the cable: in the lower current range the stability limit is well described by the stability model; in the high current range (well above the design current), however, the stability limit is much lower than expected from the strand experiment and from the model. This is understood qualitatively by an inhomogeneous distribution of the cable a.c. losses and by inhomogeneous current distribution within the cable. The reduced stability in the upper current range might be a serious problem for large superconducting coils exposed to rapidly changing fields. (author)

[en] Melt-powder melt-grown YBa₂Cu₃O₇ samples with different amounts of artificially introduced non-superconducting 211 particles were exposed to fast neutron irradiation up to a fluence of 4 x 10²¹m^-2 (E > 0.1 MeV). The influence of the irradiation on the critical current characteristics and on the irreversibility lines is investigated. Shifts of the irreversibility lines and enhanced critical current densities are observed. The results are compared with similar experiments on high quality single crystals. (author)

[en] We report on the influence of fast neutron irradiation on the critical currents in single crystalline YBa₂Cu₃O_7-δ and Bi₂Sr₂CaCu₂O_8+γ. From magnetization measurements and especially from an analysis of the irreversibility lines, models for the defect structure, effective for flux pinning in these systems, are derived. A comparison of fast neutron irradiation of YBa₂Cu₃O_7-δ at 5 K (and subsequent measurement without warming the sample above 95 K) and at ambient reactor temperature allows us to distinguish qualitatively between the contributions of defects of different size to flux pinning in these systems. (author)

[en] The critical current density in melt-textured samples of YBa₂Cu₃O₇-x obtained by the powder melting process was determined from magnetization measurements. A linear dependence between the width of the hysteresis loop and sample size was observed for both unirradiated and irradiated samples. This indicates that the critical current is circulating through the whole sample and is not disconnected by weak links, even when a magnetic field is applied in the irradiated sample. After fast neutron irradiation with fluences form 5 x 10¹⁶ to 6 x 10¹⁷ n cm^-2 (E > 0.5 MeV), significant enhancement of the critical current density, j_c, was observed. Critical current density, determined from magnetization measurements, for magnetic field perpendicular to the a-b plane j_c^ab, reaches ∼ 10⁵ A cm^-2 at 77 K in 1 T. For H parallel to the a-b plane, j_c^c along the c-axis reaches 5 x 10³ A cm^-2. An increase in the anisotropy of the critical current was observed after fast neutron irradiation in the temperature range 60-80 K. (Author)