The development of high temperature superconducting(HTS)tapes has recently made great progress,and Bi-based tapes(1 G) and YBCO coated conductor(2 G)are commercially fabricated with practical length.Application of HTS...The development of high temperature superconducting(HTS)tapes has recently made great progress,and Bi-based tapes(1 G) and YBCO coated conductor(2 G)are commercially fabricated with practical length.Application of HTS in electric power apparatuses made important achievement,various superconducting devices were demonstrated in grid,laying solid foundation for their commercialization.However,since their intrinsic microscopic defects such as weak-link,granularity,small second phase likely exist,critical current and index n value of the HTS tapes in practical length are impossible homogeneous,which have significant influences on safety,stability and efficiency of the HTS apparatuses.Therefore,critical current and index n value are two important parameters describing inhomogeneity of HTS tapes,thus two important indices for evaluating quality of practical long HTS tapes.This paper focuses on main progresses in inhomogeneity of critical current and index n value measurements on HTS tapes using contact-free methods.The statistical analytical methods evaluating the inhomogeneity of critical current and index n value are suggested.They can provide essential references for design and operation of HTS apparatuses.展开更多
Some electrical parameters of the SIS-type hysteretic underdamped Josephson junction(JJ)can be measured by its current-voltage characteristics(IVCs).Currents and voltages at JJ are commensurate with the intrinsic nois...Some electrical parameters of the SIS-type hysteretic underdamped Josephson junction(JJ)can be measured by its current-voltage characteristics(IVCs).Currents and voltages at JJ are commensurate with the intrinsic noise level of measuring instruments.This leads to the need for multiple measurements with subsequent statistical processing.In this paper,the digital algorithms are proposed for the automatic measurement of the JJ parameters by IVC.These algorithms make it possible to implement multiple measurements and check these JJ parameters in an automatic mode with the required accuracy.The complete sufficient statistics are used to minimize the root-mean-square error of parameter measurement.A sequence of current pulses with slow rising and falling edges is used to drive JJ,and synchronous current and voltage readings at JJ are used to realize measurement algorithms.The algorithm performance is estimated through computer simulations.The significant advantage of the proposed algorithms is the independence from current source noise and intrinsic noise of current and voltage meters,as well as the simple implementation in automatic digital measuring systems.The proposed algorithms can be used to control JJ parameters during mass production of superconducting integrated circuits,which will improve the production efficiency and product quality.展开更多
基金supported by the Specialized Research Fund for the Doc-toral Program of Higher Education(Grant No.D00033)the Foundation of North China Electric Power University(Grant No.KH0194)
文摘The development of high temperature superconducting(HTS)tapes has recently made great progress,and Bi-based tapes(1 G) and YBCO coated conductor(2 G)are commercially fabricated with practical length.Application of HTS in electric power apparatuses made important achievement,various superconducting devices were demonstrated in grid,laying solid foundation for their commercialization.However,since their intrinsic microscopic defects such as weak-link,granularity,small second phase likely exist,critical current and index n value of the HTS tapes in practical length are impossible homogeneous,which have significant influences on safety,stability and efficiency of the HTS apparatuses.Therefore,critical current and index n value are two important parameters describing inhomogeneity of HTS tapes,thus two important indices for evaluating quality of practical long HTS tapes.This paper focuses on main progresses in inhomogeneity of critical current and index n value measurements on HTS tapes using contact-free methods.The statistical analytical methods evaluating the inhomogeneity of critical current and index n value are suggested.They can provide essential references for design and operation of HTS apparatuses.
基金the Ministry of Science and Higher Education of the Russian Federation under Grant No.FSUN-2023-0007.
文摘Some electrical parameters of the SIS-type hysteretic underdamped Josephson junction(JJ)can be measured by its current-voltage characteristics(IVCs).Currents and voltages at JJ are commensurate with the intrinsic noise level of measuring instruments.This leads to the need for multiple measurements with subsequent statistical processing.In this paper,the digital algorithms are proposed for the automatic measurement of the JJ parameters by IVC.These algorithms make it possible to implement multiple measurements and check these JJ parameters in an automatic mode with the required accuracy.The complete sufficient statistics are used to minimize the root-mean-square error of parameter measurement.A sequence of current pulses with slow rising and falling edges is used to drive JJ,and synchronous current and voltage readings at JJ are used to realize measurement algorithms.The algorithm performance is estimated through computer simulations.The significant advantage of the proposed algorithms is the independence from current source noise and intrinsic noise of current and voltage meters,as well as the simple implementation in automatic digital measuring systems.The proposed algorithms can be used to control JJ parameters during mass production of superconducting integrated circuits,which will improve the production efficiency and product quality.
