Research On Current Carrying And Quenching Characteristics Of High Temperature Superconductors

The structure of high-temperature superconducting strip is complex,and its flow capacity is affected by physical factors such as temperature,magnetic field,and stress.Once the temperature,magnetic field,and stress exceed the critical value,the superconducting strip will quench and may even burn.Therefore,studying the critical current characteristics and quench? characteristics of superconductors is of great significance for the selection of strip material and quench protection design of superconducting devices.In this paper,the critical current characteristics of domestic high-temperature superconducting strips and foreign commercial strips in the magnetic field and bending state are compared,the quench propagation characteristics of different structural strips are tested,and the loss of double parallel superconducting strips is analyzed.Super propagation characteristics.The main work completed are as follows(1)The critical current characteristics of typical domestic and foreign commercial strips under 77 K liquid nitrogen environment were experimentally studied.Comparing the flow capacity under the magnetic field and the flow capacity under bending between the domestic and foreign tapes.The experimental results show that the gap between the two domestically produced strips and the foreign mainstream strips under the magnetic field is very small,and the material and thickness of the stabilizing layer will affect the flow capacity of the strips under bending conditions.(2)Experimental study and comparison of quench propagation characteristics of Bi-based strips and four Y-shaped strips with different structures.The results show that Bi-based strips have higher minimum quench energy,slower quench propagation speed,and better thermal stability than Y-based strips.Under the same flow-through ratio,the stainless steel stabilizing layer strip has a faster quench propagation speed and higher minimum quench energy than the copper stabilizing layer strip.(3)Tested the quench propagation characteristics of parallel parallel and stacked parallel structure,and analyzed the effect of strip shunt on quench propagation.The experimental results show that the two parallel samples have a lower quench propagation speed and higher minimum quench energy compared to a single strip sample of the same type.When the parallel samples are partially quenched,the current will be transferred from the quenched strips to the adjacent non-quenched strips.The reduction in the quenched strip transmission current will reduce the further spread of the quenched area.The shunting phenomenon of the parallel sample lags behind its local quenching,and as the quenching area expands,the shunting phenomenon gradually becomes apparent.(4)Compared two quench detection methods through experiments.The temperature detection method is not as timely as the voltage detection method due to the cooling environment,measurement delay and other factors.When the tape's voltage reaches the quench criterion,the temperature rise is not obvious.When the flow ratio is lower than 69.1%,the quench cannot be judged by the temperature.