高温超导体辐照效应研究

【作者】 赵新杰；

【导师】 郁金南； 阮克强；

【作者基本信息】 中国原子能科学研究院 ， 反应堆材料， 1999， 博士

【摘要】 在核辐射环境下，高温超导体的性能将发生变化，这是在核能领域中应用高温超导重要问题之一。本文设计了三个可进行在线测量的低温辐照靶室。一种是65K下可利用四探针法在线测量样品的零电阻温度Tc的辐照靶室；一种是30K下可利用四探针法在线测量样品的Tc的辐照靶室；另一种是30K下辐照靶室，利用在线交流磁测量方法可测量样品的临界电流密度。利用这些靶室对高温超导体进行了一系列的辐照实验，得到如下结果： 在65K温度下，35MeV高能质子对Y系123相高温超导体进行辐照，辐照剂量为2.21×10¹³／cm²，4.42×10¹³／cm²，1.77×10¹⁴／cm²，零电阻温度Tc从91K分别增大到93K，94K和97K；但是，辐照后一周，TC降低到90K。35MeV的质子对Bi系2223相辐照，剂量分别2.21×10¹³／cm²，8.82×10¹³／cm²，3.54×10¹⁴／cm²，Tc随辐照剂量的增加而增大，最大增加量达到7K。辐照后一周Tc也比辐照前降低了。 在30K下，20MeV高能质子对不同工艺条件制备的Bi系2223相高温超导体辐照，剂量从1.832×10¹⁴／cm²到8.815×10¹⁴／cm²，所有样品Tc都增加5-6K，辐照后Tc逐渐下降。 在30K下，20MeV质子辐照荧光靶产生的γ射线辐照Bi系超导样品，在线测量各样品Tc的同时，测量现场的γ射线强度，发现Tc的增加值随着γ射线强度的衰减而逐渐减少。 这表明，质子辐照高温超导体的过程中，辐照产生的伴随γ射线对超导体的Tc影响很大。而且，γ射线辐照对超导样品产生了两种效应。一种是使样品的Tco增大。这种效应是瞬时的。更多还原

【Abstract】 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.更多还原