Study On AC Loss Of Bi2212 High Temperature Superconducting CICC And The Experimental Device

More than 80%of the energy consumption of today's human society is fossil energy.However,fossil energy is not an ideal energy.It will bring about greenhouse effect and air pollution,and its reserves are limited,which is not conducive to the sustainable development of human society.Fusion energy is a clean,reliable and abundant energy source,and it is the ideal energy for the future development of human society.At present,major countries in the world are actively promoting research on fusion experiments.After years of theoretical design and experimental verification,Tokamak will develop into a reliable fusion reaction device in the future to provide unlimited energy for human beings.At the present,the world's largest international scientific and technological cooperation project is the International Thermonuclear Experimental Reactor(ITER).China has actively participated in and played an important role in this international cooperation project.The establishment of the Experimental and Advanced Superconducting Tokamak(EAST)in China,these two scientific research projects have brought China into the forefront of international fusion science research.In the future,China will continue to build The China Fusion Engineering Test Reactor(CFETR)to verify the technologies of fusion power generation and pave the way for the construction of future demonstration reactors.In the fusion reaction experimental apparatus,the plasma temperature is as high as several hundred million degrees,so that no material can be in contact with it,the magnetic field must be used to suspend and confine the plasma.Therefore,superconducting magnets are therefore a key technology that not only ensures stable operation of the nuclear fusion reaction but also determines the power of the fusion reaction.In the future,the employ of superconducting magnets instead of conventional magnets in various fusion experimental devices is the direction of development.The superconducting magnet is wound by the Cable-in-Conduit Conductors(CICC),Therefore the CICC technology is a key point in fusion experiments..In DC current or stable external magnetic field environment,CICC conductors made of composite superconducting materials will run without loss,but in actual working environment,CICC often experiences changes in current and magnetic field,even plasma disruption,in this condition the magnetic field changes drastically.In such a complicated electromagnetic environment,the quantized magnetic flux lines pinned in the superconductors inside the CICC will move to produce hysteresis loss,and various current loops will be generated between the strands and sub-cables in the CICC to generate coupling loss.Even the changing magnetic field creates eddy currents in the armor outside the CICC and creates eddy current losses.These three kinds of losses will cause the electromagnetic field energy to be dissipated into heat energy,which will increase the temperature of the CICC,increase the burden on the refrigeration system,and damage the stability of the operation of the magnet system.Therefore,it is necessary to test the AC loss performance of the conductor when designing or manufacturing a new superconducting conductor as well as superconducting joint.The conductor AC loss density data obtained from the test can be used to guide the improvement of conductor structure design,refrigeration system design,magnet design,etc.This paper introduces a new type of AC loss test device for AC loss performance testing of materials such as superconducting conductors and superconducting joints.The test device is mainly divided into three subsystems:(1)Low temperature Dewar system;(2)Superconducting dipole magnet system;(3)calorimetry test system;(4)Pick-up test system.AC loss of a sub size Bi-2212 conductor was tested using the same type of device from Twente University,the AC loss performance of the sample was analyzed in combination with the test results.and verified the reliability of the test device.The development of this device has filled the gap in domestic research and created favorable conditions for the development of superconducting materials and fusion energy in China.