Influence of Conditions of Shock-Wave Effect of Plasma on the Structure and Current-Carrying Capacity of Multilayer High-Temperature Superconducting Tapes

摘要

The article presents the results of the investigation of the influence of shock-wave effects on the structure and the critical currents of multilayer high-temperature superconductors-HTS tapes produced by the EAS-E HTS (VAC). Shock-wave exposure was carried out using an installation of a plasma focus (PF) type. It was experimentally found that an increase in the critical current by 20% or more was achieved in its own magnetic field and in external magnetic fields in the range of 0.5-2.5 T. The increase depended on the conditions of the shock-wave treatment (the distance from the plasma source (PF anode) and the number of shock wave pulses). In magnetic fields of more than 3 T, the effect of an increase in the critical current was not observed. Microstructural studies revealed both a compression and destruction of the individual layers of HTS in the strike zone depending on the conditions of the impact. The most severe degradation of the structure and the critical current was shown on the tape samples treated at distances of 25-30 mm from the PF anode. The critical current increased and exceeded the initial values of untreated tapes (75-85 A) at distances of 35-65 mm. The phase composition of HTS layers by XRD changed little after shock-wave treatment. Depending on the number of shock pulses and distance from the anode in the area of treatment, the tape's thickness was reduced owing to compression or was increased owing to swelling of the tape.