High-temperature Superconductors Radiation Effects

It is important to apply the high Tc superconductor (HTSC) to the nuclear energy. The performance of HTSC will be changed under radiation environment. There are three irradiation target chambers to be designed and carried out the irradiation experiments on HTSC superconductor at low temperature. The performance of HTSC superconductor is measured in situ under particle irradiation. The first target chamber was worked at 65K under irradiation and the Tc of HTSC superconductor was measured in situ with the standard four-probe method. Second target chamber was worked at 30K under irradiation to investigate the zero resistance temperature of HTSC superconductor in situ. The third target chamber is able to reach 20K under irradiation and the critical current density Jc of HTSC specimens was measured in situ with AC magnetic susceptibility. A series of irradiation experiments was carried out to study the irradiation effects on the HTSC superconductor. The irradiation experiments, target chambers, in situ measurement methods and the results of experiment are described in this paper.The specimens of Y-system HTCS superconductor were irradiated by 35MeV protons with fluence of 2.21 × 10¹³/cm², 4.42×10¹³/cm² and 1.77× 10¹⁴/cm² at 65K. The Tc of specimen was increased from 91K to 93K, 94K and 97K respectively. But, the Tc of specimen was decreased to 90K in one week after irradiation. The specimens of Bi-system HTSC superconductor were irradiated by 35 MeV protons with fluence of 2.21 × 10¹³/cm², 8.82 × 10¹³/cm² and 3.54×10¹⁴/cm² respectively at 65K. The Tc of specimens was increased with proton irradiation fluence increment. The largest increment of Tc is 7K. One week after irradiation, the Tc was lower than the unirradiated value. The specimens of Bi-system HTSC superconductor made by the state reaction method and the nitrate method, were irradiated by 20 MeV protons with fluence from 1.832 ×10¹⁴/cm² to 8.815 × 10¹⁴/cm² at 30K.The Tc of all specimens was increased by 5-7K. Then, the Tc decreased gradually.In order to discriminate the radiation effects on the Tc of HTSC by ionization process and displacement process at low temperature, an experiments was designed and carried out with Y ray irradiation. The Y ray was produced the fluorescent target irradiated by 22 MeV protons at 30K.