AC Susceptibility of the YBa2Cu3O7YBa_2Cu_3O_7 Coated Conductor in High Magnetic Fields

The AC susceptibility of the $YBa_2Cu_3O_7$ coated conductor in the perpendicular applied AC magnetic field was investigated using an inductive experimental setup with a pair of coils connected in opposite. A harmonic homogeneous AC magnetic field was applied perpendicularly to the wide face of the $YBa_2Cu_3O_7$ coated tape. Together with this AC field, a parallel background DC magnetic field up to 14 T was applied perpendicularly to the tape. The measurements were performed at several constant temperatures in the range 3-50 K. In the region of high background DC fields (8-14 T) no influence of the tape's ferromagnetic substrate was detected, despite of the low measurement temperatures employed. The estimate of the critical current density $(j_c)$ at 20 K and 14 T, based on the position of the imaginary AC susceptibility peak, gives the value $j_c$=0.53 MA/$cm^2$

DC Characterization of the Coaxial Superconducting Cable

Coaxial cable model with superconducting core and superconducting shield conductor was constructed and tested in DC regime. While the core was already examined in our previous works, in this contribution the detailed study of the superconducting shield conductor in DC conditions is presented. It consists of 16 ReBCO coated tapes with critical current 35 A each connected in parallel. Using shunts with known values placed in series the currents in individual tapes were possible to measure. Distribution of the total cable current into the individual tapes was monitored and its influence on critical current of the cable is discussed

Numerical modelling of a HTS cable in AC regime

The current repartition inside a HTS cable is very important for determining its AC losses and can be influenced by the uniformity of several parameters, either linked to the physical properties of the individual tapes (critical current Ic and power index n) or due to the manufacturing process (contact resistance). This work investigates the importance of the non-uniformity of these parameters for a manufactured 16-tape straight superconducting cable by means of finite element method (FEM) simulations. The utilized non-linear E-J model includes the anisotropic dependence of the critical current density and the power index on the local magnetic field. It is shown that the non-uniformity of the cable parameters influences the behaviour of the individual tapes, but not that of the whole cable. The utilized FEM model has been validated by a comparison with electrical measurements of the cable AC losses, as well as with the results of another simpler numerical model, which considers the cable from the macroscopic point of view