| High performance superconducting wire is the key of superconducting magnetic field technology.Nb3Al is a high magnetic material developed in recent years.Compared with Nb3Sn,Nb3Al superconducting critical temperature(Tc)is a little higher than 19.3 K;Nb3Al has higher upper critical field,Hc2 and larger critical current density,Jc and excellent stress/strain tolerance,thus which is considered as a high field superconducting magnet ideal choice,the respect such as in ITER,high-energy accelerator and NMR has huge potential application.In the future,with the development of fusion power demonstration reactor and high-energy particle accelerator,higher demand for the properties of superconducting wires will be constantly proposed.The electromagnetic performance and mechanical properties of Nb3Al superconducting wire are far better than the Nb3Sn,which is expected to be the preferred material for nuclear fusion power generation technology with superconducting controllable magnetic confinement.Therefore,the preparation of the practical Nb3Al superconducting wire has good engineering application background and foreground.Rapid Heating-Quenching and Transformation(RHQT)is the most reasonable technical preparation of Nb3Al superconducting wires,the fabrication was adopted by Powder-in-Tube wire in this paper.From the traditional granularity of powder,and we try to improve the existing method of RHQ.In the process of rapid heating,the sample was rapidly heated(1940 ?)in the constant temperature processing within 4 s,which can form high purity Nb3Al phase.In the fast cooling process,the sample is parallel to the surface of Ga bath.This structure ensures that the coling rate in whole sample being constant during cooling process and saves the precursor wire.Based on the optimization of heating and cooling structure,the control circuit is designed and produced based on C8051F410 single-chip,and which can effectively heat and quench the sample within 0.1 s.The properties of Nb3Al phase(i.e.,Nb3Al superconductor must be stoichiometric and its phase exists around 1940?),which is necessary to monitor real-time and control the temperature,as a result,an research was contrasted,the temperature measurement is presented based on the principle of radiation temperature measurement way of colorimetric method of temperature measurement,using the charge-coupled device(CCD)design and producing a set of non-contact high temperature thermometer,which can rapidly and accurately measured temperature changes in the process of RHQ precursor wire,and no direct contact with the precursor wire during temperature measurement process,no effect on the temperature of the precursor wire was realized.In this thesis,the principle of color temperature measurement of CCD and its calculation method are described in detail.Primarily using Vsual Basic language program,developed the 1800? to 2500? colorimetry optical temperature measuring device,which can realize±10? temperature measurement accuracy;The fastest temperature measurement is 0.06 ms.Devices directly output voltage PID,the control numerical current source can be 1940? control response time of the phase change more than 0.001 s.By high-speed CCD non-contact optical measurement temperature quickly recognize the temperature control,if the detected temperature fluctuations,directly controlled by the PID output voltage to adjust temperature,precisely control Nb3Al preparation temperature and heating time,to more accurately grasp Nb3Al transform into fine phase during rapid heating process. |
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