A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction.The molecular structure and optical properties wer...A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction.The molecular structure and optical properties were highly investigated through ~1H-NMR,UV and PL spectroscopy.The quenching behavior was also investigated,and the results demonstrate that incomplete quenching exists,which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents,prob...展开更多
No-insulation(NI)high-temperature superconducting(HTS)coil wound with parallel-stacked tapes emerges as a prospective choice for high-field fusion magnets owing to lower inductance and faster ramping rate.The parallel...No-insulation(NI)high-temperature superconducting(HTS)coil wound with parallel-stacked tapes emerges as a prospective choice for high-field fusion magnets owing to lower inductance and faster ramping rate.The parallel stacked-tape structure leads to new current redistribution among stacked tapes in each turn during local quenches,which also considerably changes the current redistribution behavior through inter-turn contacts.Therefore,quench behaviors of parallel-wound no-insulation(PWNI)coil should differ from its counterpart wound with single tape,which are still unknown.This study is to illustrate quench behaviors of PWNI HTS coils induced by local hot spot.A multi-physics model integrating an equivalent circuit network,a FEM heat transfer module,and a FEM T-A model is developed to analyze the electromagnetic and thermal characteristics of PWNI HTS coils during quench.Results show that the transport currents are mainly redistributed among parallel-stacked tapes through terminal resistances when a local hot spot happens on one tape,while being less dependent on turn-to-turn electrical contacts.It leads to a coupling current within PWNI coils that is not present in NI coils wound with single tape(single-wound no-insulation(SWNI)coil),resulting in a highly non-uniform transport current distribution among parallel-wound tapes.The reduced terminal joint resistances further enhance the coupling current,potentially leading to an extra overcurrent quench risk in PWNI coils.Moreover,the current redistribution between parallel-stacked tapes inhibits the turn-to-turn current redistribution in the PWNI coil,thus significantly reducing its magnetic field degradation under a high heat disturbance,which can be almost less than half of the SWNI counterpart in this study.These results offer important theoretical guidance to safety operation and robustness improvement of high-field HTS magnets wound by PWNI technique.展开更多
基金supported by the National Natural Science Foundation of China(Nos.20774043,20874048)the Fok Ying-Tong Education Foundation(No.111051)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK2008453)the Scientific Research Foundation of Nanjing University of Posts and Telecommunications (NUPT)(Nos.NY207035 and NY207011)
文摘A cationic poly(p-phenylene vinylene) related copolymer without bulky phenylene substitutents attached to the conjugated backbone was prepared through Wittig reaction.The molecular structure and optical properties were highly investigated through ~1H-NMR,UV and PL spectroscopy.The quenching behavior was also investigated,and the results demonstrate that incomplete quenching exists,which is consistent with the cationic poly(p-phenylene vinylene) related copolymer containing bulky phenylene substitutents,prob...
基金sponsored by National Key R&D Program of China(No.2023YFE0118100)The work is also sponsored by National Natural Science Foundation of China(No.52207028)+1 种基金The work is also spon-sored by Shanghai Science&Technology Innovation Action Program(No.23511101800)The work is also sponsored by Natural Science Foundation of Chongqing(No.2022NSCQ-MSX1512).
文摘No-insulation(NI)high-temperature superconducting(HTS)coil wound with parallel-stacked tapes emerges as a prospective choice for high-field fusion magnets owing to lower inductance and faster ramping rate.The parallel stacked-tape structure leads to new current redistribution among stacked tapes in each turn during local quenches,which also considerably changes the current redistribution behavior through inter-turn contacts.Therefore,quench behaviors of parallel-wound no-insulation(PWNI)coil should differ from its counterpart wound with single tape,which are still unknown.This study is to illustrate quench behaviors of PWNI HTS coils induced by local hot spot.A multi-physics model integrating an equivalent circuit network,a FEM heat transfer module,and a FEM T-A model is developed to analyze the electromagnetic and thermal characteristics of PWNI HTS coils during quench.Results show that the transport currents are mainly redistributed among parallel-stacked tapes through terminal resistances when a local hot spot happens on one tape,while being less dependent on turn-to-turn electrical contacts.It leads to a coupling current within PWNI coils that is not present in NI coils wound with single tape(single-wound no-insulation(SWNI)coil),resulting in a highly non-uniform transport current distribution among parallel-wound tapes.The reduced terminal joint resistances further enhance the coupling current,potentially leading to an extra overcurrent quench risk in PWNI coils.Moreover,the current redistribution between parallel-stacked tapes inhibits the turn-to-turn current redistribution in the PWNI coil,thus significantly reducing its magnetic field degradation under a high heat disturbance,which can be almost less than half of the SWNI counterpart in this study.These results offer important theoretical guidance to safety operation and robustness improvement of high-field HTS magnets wound by PWNI technique.
