ENEA is currently involved in the design and manufacture of a fully high temperature superconductor (HTS) cable in the cable-in-conduit conductor (CICC) configuration exploiting commercial second generation ReBaCuO (Re: Rare Earth and Y) coated-conductors. The final cable will be composed of five slots obtained in a helically twisted aluminum central core and filled with 2G tape stacks. This conductor is designed to operate above 10 kA in 12 T background field at 4.2 K or at about 10 kA in self-field at 77 K. A first sample of about 1-m length with one fully superconductive slot has been manufactured using 15 tapes provided by Superpower, Inc. and 12 tapes from the SuNAM Company grouped in two sub-stacks divided by a Kapton foil. Each tape of the stack has been characterized individually by measuring critical current values I_c at 77 K (liquid N₂ bath) in self-field and n-index. Results revealed that the tapes showed no degradation of critical current values when compared with suppliers specifications confirming that the proposed manufacturing process is fully compatible with commercial coated-conductors. Inter-tape resistance(R_inter) has also been measured and the observed dependence of R_inter on the tape position in the stack has been put in correlation with transverse stress distribution calculated by finite element models. A second sample with a full superconducting slot has been manufactured using 18 SuNAM tapes. Preliminary results on the stack transport measurements performed at 77 K in self-field will be presented and discussed. All the samples were manufactured by using already existing industrial equipments at Tratos Cavi SpA.

An outstanding current carrying performance (namely critical current density, J_c) over a broad temperature range of 10–77 K for magnetic fields up to 12 T is reported for films of YBa₂Cu₃O_7−x with Ba₂Y(Nb,Ta)O₆ inclusion pinning centres (YBCO-BYNTO) and thicknesses in the range of 220–500 nm. J_c values of 10 MA cm⁻² were measured at 30 K – 5 T and 10 K – 9 T with a corresponding maximum of the pinning force density at 10 K close to 1 TN m⁻³. The system is very flexible regarding properties and microstructure tuning, and the growth window for achieving a particular microstructure is wide, which is very important for industrial processing. Hence, the dependence of J_c on the magnetic field angle was readily controlled by fine tuning the pinning microstructure. Transmission electron microscopy (TEM) analysis highlighted that higher growth rates induce more splayed and denser BYNTO nanocolumns with a matching field as high as 5.2 T. Correspondingly, a strong peak at the B||c-axis is noticed when the density of vortices is lower than the nanocolumn density. YBCO-BYNTO is a very robust and reproducible composite system for high-current coated conductors over an extended range of magnetic fields and temperatures.

Pulsed laser deposited thin Y Ba₂Cu₃O_7−x (YBCO) films with pinning additions of 5 at. % Ba₂Y TaO₆ (BYTO) were compared to films with 2.5 at. % Ba₂Y TaO₆ + 2.5 at. % Ba₂Y NbO₆ (BYNTO) additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO) and 11 T (YBCO-BYNTO), representing the highest ever achieved values in YBCO films.

The structural and transport properties of YBa ₂ Cu ₃ O _{7− x} films grown by pulsed laser deposition with mixed 2.5 mol% Ba ₂ YTaO ₆ (BYTO) and 2.5 mol% Ba ₂ YNbO ₆ (BYNO) double-perovskite secondary phases are investigated in an extended film growth rate, R = 0.02–1.8 nm s ⁻¹ . The effect of R on the film microstructure analyzed by TEM techniques shows an evolution from sparse and straight to denser, thinner and splayed continuous columns, with mixed BYNO + BYTO (BYNTO) composition, as R increases from 0.02 nm s ⁻¹ to 1.2 nm s ⁻¹ . This microstructure results in very efficient flux pinning at 77 K, leading to a remarkable improvement in the critical current density (J _c ) behaviour, with the maximum pinning force density F _p (Max) = 13.5 GN m ⁻³ and the irreversibility field in excess of 11 T. In this range, the magnetic field values at which the F _p is maximized varies from 1 T to 5 T, being related to the BYNTO columnar density. The film deposited when R = 0.3 nm s ⁻¹ exhibits the best performances over the whole temperature and magnetic field ranges, achieving F _p (Max) = 900 GN m ⁻³ at 10 K and 12 T. At higher rates, R > 1.2 nm s ⁻¹ , BYNTO columns show a meandering nature and are prone to form short nanorods. In addition, in the YBCO film matrix a more disordered structure with a high density of short stacking faults is observed. From the analysis of the F _p ( H , T ) curves it emerges that in films deposited at the high R limit, the vortex pinning is no longer dominated by BYNTO columnar defects, but by a new mechanism showing the typical temperature scaling law. Even though this microstructure produces a limited improvement at 77 K, it exhibits a strong J _c improvement at lower temperature with F _p = 700 GN m ⁻³ at 10 K, 12 T and 900 GN m ⁻³ at 4.2 K, 18 T.

Extensive applications of YBa ₂ Cu ₃ O _7-x (YBCO) tapes require a comprehensive knowledge of their behavior in every possible operating condition. In this paper, the thermal stability behavior of a conduction-cooled pancake coil wound with commercial YBCO coated conductors is reported from both the experimental and numerical point of view. The coil stability against heat disturbances is studied in terms of minimum quench energy and normal zone propagation velocity (NZPV) for different values of the coil currents at different temperatures. The quench dynamics of the tape is compared between experiment and the numerical analysis, obtaining a reasonable agreement for voltage traces, NZPV, and temperatures. The model allows a wide range of case studies that can be used to suggest appropriate solutions for the design of detection and protection systems.