A New Testing Device For Strain Influence On Wires:Research On Mechanical And Electrical Characteristics Of Superconducting Wires

At present,human beings rely mainly on fossil fuels such as petroleum,coal and natural gas,which bring various pollution and greenhouse effect to the earth.And in the future,human beings will face the threat of resource depletion if we depend on too much on them.Fusion energy,as a clean energy,is inexhaustible and is an ideal future energy for mankind.Therefore,all countries in the world are actively engaged in the research and development of fusion energy.Tokamak magnetic confinement fusion device is a kind of device which can produce reliable fusion energy,which has been verified by the theory and practice,and full-superconducting Tokamak is an important guarantee for continuous operation of fusion.Based on the successful establishment and operation of the full-superconducting Tokamak device-EAST(Experimental Advanced Superstructure Tokamak),China has actively participated in the construction of the International Thermonuclear Experimental Reactor(ITER)project.Meanwhile,China is building its own fusion engineering test reactor-CFETR(China Fusion Engineering Test Reactor).In these large fusion devices,the magnet technology is the core,which determines whether the device can be stable and continuous.At present,international large fusion magnets are usually made of CICC(Cable in Conduit Conductor).And superconducting wires are main components of the CICC conductor,so the performance of superconducting wires will ultimately affect the magnetic performance of the fusion device.In the process of manufacturing and operating CICCs,differences in thermal contraction of the composite materials in a CICC and electromagnetic load under magnetic field will inevitably cause the deformation of superconducting material,which will result in the performance degradation of superconducting wires in the cable.In the future,with the development of magnet technology,high magnetic field will be increasingly required.In order to manufacture higher field magnet,the high-temperature superconducting materials which have high upper critical field are preferable choices for further development.On the other hand,the higher the magnetic field is,the bigger the deformation of wires will be,which will cause more severe performance degradation of superconducting wires,especially for Bi-2212 wire which is sensitive to strain.In this thesis,we are introducing a novel testing device SUPUM(Superconductor under Mechanical-Stress)which can be used to verify and evaluate the quantitative impact of wire deformation on the performance of wires in cables,especially for high temperature superconducting wires.This device incorporates three modules:(1)tensile module;(2)bending module;(3)local contact module.Then,the mechanical and critical performance of high temperature superconducting material under strain was studied by using the device.We have performed experiments on Bi-2212 RW(round wire)to validate our device and to demonstrate that this work is essential for further design and optimization of CICC.