Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-01
Abstract： The Tianhuan One (CAT-1: China Astro-Torus 1) is the first magnetically confined plasma device design in China using a magnetically floating dipole field magnet. According to the overall objectives and parameter design requirements of the CAT-1 device, In this paper, a simplified linear current model is used to analyze and calculate the stability of the floating magnet based on methods such as vector magnetic field, mechanical balance and dynamics. The design parameters of the floating magnet, levitation coil, and TSR (Tilt-Slider-Rotation) coil of the device, such as the overall size, spatial position and layout, current, weight, characteristic stability performance and their relationship are given. The results show that for the CAT-1 device, the optimal value of the levitation coil radius is 1.7 m, and the corresponding current is 3.49 kA for the design goal with a floating magnet current of 5MA and a height of 2.0 m. In order to achieve effective resistance and control of the floating magnet offset movement, the working area near the balance point should be limited to Δ z < 100 mm、er < 50 mm、 α< π/24.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-04-15
Abstract： CAT-1 (China Astro-Torus 1) is a levitated dipole field magnetic confinement device, which mainly used for dipole plasma physics experiments, requiring a central floatin
g superconducting coil to be stably levitated for at least 5hr without cooling or power supply. In this paper, a levitation control system of coupling superconducting levitation coil and floating coil is designed. In order to ensure the stable levitation of 1200 kg, 5 MA floating magnet, Simulink model of the control system is established and simulated. Based on Routh-Hurwitz stability criterion, the influence of PID（Proportion-Integral-Derivative） control strategy on stability control is studied. The selection range of stability control parameters is determined: Under ideal conditions, delay time of the PD（Proportion-Derivative） control system is 0.0463s, rise time is 0.1545s, peak time is 0.6283s, adjustment time is 0.0848s, and overshot δ=1.6. The results show that PID can restore the levitated superconducting ring to the preset balance position in a short time, and the load of the circuit can be greatly reduced by adopting the appropriate starting mode. The results provide key technical support for the design and development of levitated superconducting dipole field devices.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-03-03
Abstract： In response to the requirements of the dipole field plasma physics experiment for（CAT-1: China Astro Torus 1）, the device requires the center floating superconducting coil to be stably suspended for at least 5 hours without cooling and power supply conditions. A suspension control system for the coupling system of the superconducting lifting coil and the center floating coil was designed. To ensure the stable suspension of 1200kg and 5MA suspension magnets, the Simulink model of the control system was established and simulated. Based on the Routh Hurwitz stability criterion, the influence of PID control strategy on stable control was studied, and the range of stable control parameters was determined: when the power response frequency of the driving lifting coil should be greater than 9 Hz, and the error of the output current is less than 0.1%, the most effective control effect of the PD control system under ideal conditions is a delay time of 0.0463 seconds Rise time is 0.1545s, peak time is 0.6283s, adjustment time is 0.0848s, overshoot =1.6. The steady-state error err is less than 0.05mm, indicating that the corresponding frequency of the power supply is greater than 9Hz and the output error is less than 0.05%. The results show that based on PID, the suspended superconducting ring can be placed in the preset position in a short period of time, and under the appropriate starting method, the load of the circuit can be greatly reduced, providing strong support for the technical feasibility of the suspended superconducting dipole field device.
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2019-03-05 Cooperative journals: 《电气工程学报》
Abstract：本文测量了在 30 ～ 90℃，1 ～ 19kV/mm 下三种接触方式的交联聚乙烯 /三元乙丙橡胶双层介质电导特性，分析了电场、界面以及温度对双层介质电导的影响机理。研究表明：随着电场升高，三种双层介质电导率的电场依赖性均随之升高；热压接触式双层介质电导率的温度敏感性强于其他两种物理接触界面的双层介质，温度对化学界面的影响比对物理界面的影响更大。双层介质电导存在类似半导体物理中 PN结的极性现象，热压式接触双层介质电导率极性效应与另外两种双层介质相反。界面状态对双层介质的电导特性有着明显的影响。
Subjects: Dynamic and Electric Engineering >> Electrical Engineering submitted time 2019-03-05 Cooperative journals: 《电气工程学报》
Abstract：为了保证高压直流电缆满足预期的使用条件和长期运行的稳定性，需要对高压直流电缆进行型式试验。对型式试验前后电缆的主绝缘由内层到外层交联副产物含量变化以及不同温度下电流密度随电场强度变化曲线进行分析。实验结果表明，型式试验抑制了低场强下的载流子迁移，促进交联副产物由内层向中层和外层迁移，且交联副产物的含量越多，温度越高，电流密度的阈值电场越低。
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