To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiate...To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa_2Cu_3O_(7-x)(YBCO) thin films are carried out. From micro-Raman spectroscopy and x-ray diffraction studies, the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase. The results indicate that the defects induced in the conducting CuO_2 planes, such as increased oxygen vacancies and interstitials, can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation, which is confirmed in the electrical transport measurements. Especially, zero-resistance temperature TC_0 is not observed at a fluence of 10^(15)p/cm^2.Furthermore, the variation of activation energy U_0 can be explained by the plastic-flux creep theory, which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects. Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films. These disorders are likely to cause flux creep by thermally assisted flux flow, which may increase noise and reduce the precision of superconducting devices.展开更多
The ghost dust clouds in the vicinity of Earth-Moon triangular libration points are known as the“Kordylewski clouds”(KDCs).Objects in the KDCs may give hints to the physical,chemical,and dynamical properties of the ...The ghost dust clouds in the vicinity of Earth-Moon triangular libration points are known as the“Kordylewski clouds”(KDCs).Objects in the KDCs may give hints to the physical,chemical,and dynamical properties of the solar system.As a result,in situ exploration of the KDCs can help us understand the evolution of our solar system.This paper first summarizes the observation history of the KDCs.Based on the properties of the KDCs,a ground-and space-based observation concept is proposed,using the CAST 100 platform developed by DFH and ground stations.Some details of the concept are exploited.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61473023)the Aerospace Science and Technology Innovation Fund,CASCInternational S&T Cooperation Program of China(ISTCP)(Grant No.2015DFR80190)
文摘To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa_2Cu_3O_(7-x)(YBCO) thin films are carried out. From micro-Raman spectroscopy and x-ray diffraction studies, the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase. The results indicate that the defects induced in the conducting CuO_2 planes, such as increased oxygen vacancies and interstitials, can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation, which is confirmed in the electrical transport measurements. Especially, zero-resistance temperature TC_0 is not observed at a fluence of 10^(15)p/cm^2.Furthermore, the variation of activation energy U_0 can be explained by the plastic-flux creep theory, which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects. Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films. These disorders are likely to cause flux creep by thermally assisted flux flow, which may increase noise and reduce the precision of superconducting devices.
基金This study is supported by the National Natural Science Foundation of China(11773004).
文摘The ghost dust clouds in the vicinity of Earth-Moon triangular libration points are known as the“Kordylewski clouds”(KDCs).Objects in the KDCs may give hints to the physical,chemical,and dynamical properties of the solar system.As a result,in situ exploration of the KDCs can help us understand the evolution of our solar system.This paper first summarizes the observation history of the KDCs.Based on the properties of the KDCs,a ground-and space-based observation concept is proposed,using the CAST 100 platform developed by DFH and ground stations.Some details of the concept are exploited.
