The central solenoid（CS）is one of the key components of the International Thermonuclear Experimental Reactor（ITER）tokamak and which is often considered as the heart of this fusion reactor.This solenoid will be bui...The central solenoid（CS）is one of the key components of the International Thermonuclear Experimental Reactor（ITER）tokamak and which is often considered as the heart of this fusion reactor.This solenoid will be built by using Nb3Sn cablein-conduit conductors（CICC）,capable of generating a 13 T magnetic field.In order to assess the performance of the Nb3Sn CICC in nearly the ITER condition,many short samples have been evaluated at the SULTAN test facility（the background magnetic field is of 10.85 T with the uniform length of 400 mm at 1%homogeneity）in Centre de Recherches en Physique des Plasma（CRPP）.It is found that the samples with pseudo-long twist pitch（including baseline specimens）show a significant degradation in the current-sharing temperature（Tcs）,while the qualification tests of all short twist pitch（STP）samples,which show no degradation versus electromagnetic cycling,even exhibits an increase of Tcs.This behavior was perfectly reproduced in the coil experiments at the central solenoid model coil（CSMC）facility last year.In this paper,the complex structure of the Nb3Sn CICC would be simplified into a wire rope consisting of six petals and a cooling spiral.An analytical formula for the Tcs behavior as a function of the axial strain of the cable is presented.Based on this,the effects of twist pitch,axial and transverse stiffness,thermal mismatch,cycling number,magnetic distribution,etc.,on the axial strain are discussed systematically.The calculated Tcs behavior with cycle number show consistency with the previous experimental results qualitatively and quantitatively.Lastly,we focus on the relationship between Tcs and axial strain of the cable,and we conclude that the Tcs behavior caused by electromagnetic cycles is determined by the cable axial strain.Once the cable is in a compression situation,this compression strain and its accumulation would lead to the Tcs degradation.The experimental observation of the Tcs enhancement in the CS STP samples should be considered as a contribution of the shorter length of the high field zone in SULTAN and CSMC devices,as well as the tight cable structure.展开更多
Through magnetization measurement with a SQUID magnetometer the heat treatment optimization of an international thermonuclear experimental reactor （ITER）-type internal-Sn Nb3Sn superconducting wire has been investig...Through magnetization measurement with a SQUID magnetometer the heat treatment optimization of an international thermonuclear experimental reactor （ITER）-type internal-Sn Nb3Sn superconducting wire has been investigated. The irreversibility temperature T^＊ （H）, which is mainly dependent on A15 phase composition, was obtained by a warming and cooling cycle at a fixed field. The hysteresis width △M（H） which reflects the flux pinning situation of the A15 phase is determined by the sweeping of magnetic field at a constant temperature. The results obtained from differently heat-treated samples show that the combination of T^＊ （H） with AM（H） measurement is very effective for optimizing the heat reaction process. The heat treatment condition of the ITER-type wire is optimized at 675℃/128 h, which results in a composition closer to stoichiometric Nb3Sn and a state with best flux pinning.展开更多
Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magn...Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves. For amorphous alloy, the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.展开更多
Adoption of powder-in-tube method to fabricatesuperconducting wire can realize a large application ofNb3Al prepared by powder metallurgy. Powder metallurgywas used to synthesize Nb3Al under various heat-treatmentcondi...Adoption of powder-in-tube method to fabricatesuperconducting wire can realize a large application ofNb3Al prepared by powder metallurgy. Powder metallurgywas used to synthesize Nb3Al under various heat-treatmentconditions, annealing temperature was varied from 700 to1,000 C and heating time was varied from 10 to 50 h.X-ray diffraction patterns reveal that a reaction between Nband Al took place and formed NbAl3 phase. Under currentheat-treatment conditions （annealing temperature wasvaried from 700 to 1,000 C and heating time was variedfrom 10 to 50 h）, NbAl3 was so stable that it did not furtherreact with the unreacted Nb and was not sensitive to theheat-treatment condition. By mechanical alloying, adoptionof high-energy ball milling significantly decreases particlesize and enhances surface free energy, which promotes theformation of Nb3Al phase. X-ray diffraction patternsindicate that relatively pure Nb3Al phase was obtainedunder the same heat-treatment condition. Energy-dispersiveX-ray analysis measurement demonstrates that theobtained samples were close to the right stoichiometry ofA15 structure Nb3Al.展开更多
基金supported by the National Natural Science Foundation of China(Grant 11622217)the National Key Project of Scientific Instrument and Equipment Development(Grant 11327802)supported by the Fundamental Research Funds for the Central Universities(Grants lzujbky-2017-ot18,lzujbky-2017-k18)
文摘The central solenoid（CS）is one of the key components of the International Thermonuclear Experimental Reactor（ITER）tokamak and which is often considered as the heart of this fusion reactor.This solenoid will be built by using Nb3Sn cablein-conduit conductors（CICC）,capable of generating a 13 T magnetic field.In order to assess the performance of the Nb3Sn CICC in nearly the ITER condition,many short samples have been evaluated at the SULTAN test facility（the background magnetic field is of 10.85 T with the uniform length of 400 mm at 1%homogeneity）in Centre de Recherches en Physique des Plasma（CRPP）.It is found that the samples with pseudo-long twist pitch（including baseline specimens）show a significant degradation in the current-sharing temperature（Tcs）,while the qualification tests of all short twist pitch（STP）samples,which show no degradation versus electromagnetic cycling,even exhibits an increase of Tcs.This behavior was perfectly reproduced in the coil experiments at the central solenoid model coil（CSMC）facility last year.In this paper,the complex structure of the Nb3Sn CICC would be simplified into a wire rope consisting of six petals and a cooling spiral.An analytical formula for the Tcs behavior as a function of the axial strain of the cable is presented.Based on this,the effects of twist pitch,axial and transverse stiffness,thermal mismatch,cycling number,magnetic distribution,etc.,on the axial strain are discussed systematically.The calculated Tcs behavior with cycle number show consistency with the previous experimental results qualitatively and quantitatively.Lastly,we focus on the relationship between Tcs and axial strain of the cable,and we conclude that the Tcs behavior caused by electromagnetic cycles is determined by the cable axial strain.Once the cable is in a compression situation,this compression strain and its accumulation would lead to the Tcs degradation.The experimental observation of the Tcs enhancement in the CS STP samples should be considered as a contribution of the shorter length of the high field zone in SULTAN and CSMC devices,as well as the tight cable structure.
文摘Through magnetization measurement with a SQUID magnetometer the heat treatment optimization of an international thermonuclear experimental reactor （ITER）-type internal-Sn Nb3Sn superconducting wire has been investigated. The irreversibility temperature T^＊ （H）, which is mainly dependent on A15 phase composition, was obtained by a warming and cooling cycle at a fixed field. The hysteresis width △M（H） which reflects the flux pinning situation of the A15 phase is determined by the sweeping of magnetic field at a constant temperature. The results obtained from differently heat-treated samples show that the combination of T^＊ （H） with AM（H） measurement is very effective for optimizing the heat reaction process. The heat treatment condition of the ITER-type wire is optimized at 675℃/128 h, which results in a composition closer to stoichiometric Nb3Sn and a state with best flux pinning.
基金This work was supported by the National Natural Science Foundation of China(No.59871013).
文摘Under different magnetic field intensities, the dependence of the permeability μ on temperature T(μ-T curve) for the Fe7.3Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated. The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves. For amorphous alloy, the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.
基金supported by the National Magnetic Confinement Fusion Science Program (Grant No. 2011 GB112001)the Program of International S&T Cooperation (Grant No. 2013DFA51050)+3 种基金the National Natural Science Foundation of China (Grant Nos. 11104224, 11004162, 51377138, and 51302224)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110184120029)the Fundamental Research Funds for the Central Universities (Grant Nos. 2682013ZT16, SWJTU11ZT31, 2682013CX004, and SWJTU11BR063)the Science Foundation of Sichuan Province (Grant Nos. 2011JY0031 and 2011JY0130)
文摘Adoption of powder-in-tube method to fabricatesuperconducting wire can realize a large application ofNb3Al prepared by powder metallurgy. Powder metallurgywas used to synthesize Nb3Al under various heat-treatmentconditions, annealing temperature was varied from 700 to1,000 C and heating time was varied from 10 to 50 h.X-ray diffraction patterns reveal that a reaction between Nband Al took place and formed NbAl3 phase. Under currentheat-treatment conditions （annealing temperature wasvaried from 700 to 1,000 C and heating time was variedfrom 10 to 50 h）, NbAl3 was so stable that it did not furtherreact with the unreacted Nb and was not sensitive to theheat-treatment condition. By mechanical alloying, adoptionof high-energy ball milling significantly decreases particlesize and enhances surface free energy, which promotes theformation of Nb3Al phase. X-ray diffraction patternsindicate that relatively pure Nb3Al phase was obtainedunder the same heat-treatment condition. Energy-dispersiveX-ray analysis measurement demonstrates that theobtained samples were close to the right stoichiometry ofA15 structure Nb3Al.
