This paper reviews the Pb- and Cd-free NbTi/Nb₃Sn superconducting joint technology and the related technologies. The key to the Pb-free joining process is the use of a high-temperature tolerable Nb superconducting alloy as an intermediate material, which enables metallic bonding between the Nb₃Sn wire and the Nb superconducting alloy intermediate material through a chemical reaction, and between the NbTi wire and the Nb superconducting alloy intermediate material by pressure welding. Consequently, the NbTi/Nb₃Sn superconducting joint is realized. This novel technology is expected to be used in the world’s first Pb-free, environmentally friendly NMR superconducting magnets.

This paper discusses the development of replacing klystron magnets used in the Compact Linear Collider （CLIC） project at CERN with MgB₂ superconducting magnets. The study confirms that this replacement can reduce power consumption to less than one-seventh of that of the current normal conducting magnets, and to one-thirteenth when two units are connected in parallel as a pair klystron system. Additionally, the paper presents the results of combination tests with klystron at CERN. It also covers the development status of high-strain-resistant MgB₂ wires and recent advancements in MgB₂ magnet technology.

We review superconductors with a chiral crystal structure （chiral superconductors）, which lack horizontal and vertical mirrors and an inversion center. Very few chiral superconductors have been reported so far; this is primarily because material design of chiral inorganic crystals still remains challenging. Therefore, we show that an element substitution of the existing chiral inorganic materials could be a useful method for the material discovery of chiral superconductors. We present a new family of chiral intermetallic superconductors TaAl_xGe_2－x. Magnetic susceptibility, magnetization curves, and electrical resistivity revealed type-II superconductivity, with a superconducting transition temperature T_c from 2.0 to 2.2 K in TaAl_xGe_2－x （x = 0.2－0.4）. An emergence of superconductivity is discussed in relation to changes in the lattice constants associated with the Al substitution. These results suggest that the C40-type chiral disilicides and digermanides TX₂ （T = Nb, Ta and X = Si, Ge） are a promising family of materials for exploring chiral superconductors. Chiral superconductors could potentially have unique attractive properties, which have not been studied well in noncentrosymmetric superconductors, as chiral superconductors exhibit nontrivial physical phenomena, such as nonreciprocal electrical magnetochiral anisotropy and chirality-induced spin selectivity, in addition to the formation of unconventional Cooper pair states and enhancing the properties of superconductivity.