In large tokamaks, disruption of high current plasma would damage plasma facing component surfaces （PFCs） or other inner components due to high heat load, electromagnetic force load and runaway electrons. It would a...In large tokamaks, disruption of high current plasma would damage plasma facing component surfaces （PFCs） or other inner components due to high heat load, electromagnetic force load and runaway electrons. It would also influence the subsequent plasma discharge due to production of impurities during disruptions. So the avoidance and mitigation of disruptions is essential for the next generation of tokamaks, such as ITER. Massive gas injection （MGI） is a promising method of disruption mitigation. A new fast valve has been developed successfully on EAST. The valve can be opened in 0.5 ms, and the duration of open state is largely dependent on the gas pressure and capacitor voltage. The throughput of the valve can be adjusted from 0 mbar·L to 700 mbar·L by changing the capacitor voltage and gas pressure. The response time and throughput of the fast valve can meet the requirement of disruption mitigation on EAST. In the last round campaign of EAST and HT-7 in 2010, the fast valve has operated successfully. He and Ar was used for the disruption mitigation on HT-7. By injecting the proper amount of gas, the current quench rate could be slowed down, and the impurities radiation would be greatly improved. In elongated plasmas of EAST discharges, the experimental data is opposite to that which is expected.展开更多
A gas injector was designed for the 400 J/pulse prototype of the planar inductive pulsed plasma thruster（IPPT） developed by the National University of Defense Technology（NUDT_IPPTx）.As the gas puff distribution ov...A gas injector was designed for the 400 J/pulse prototype of the planar inductive pulsed plasma thruster（IPPT） developed by the National University of Defense Technology（NUDT_IPPTx）.As the gas puff distribution over the coil surface is critical to the NUDT_IPPTx functioning efficiently, a fast ionization gauge was developed to investigate the neutral gas pressure profiles to seek the critical time when the thruster is ignited. The gauge was calibrated for argon by using a capacitance manometer. Time-resolved pressure profiles have been acquired in the condition of the gas puff mass matching with the discharge energy and the drive coil parameters of the NUDT_IPPTx. It is demonstrated that the gas injector can supply a gas puff with a sufficiently steep（dp/dt？≈？770 kPa s-1） leading and trailing edge, and the gas puff can be compressed against the drive coil as expected. The critical ignition moment is considered to appear at some instant between 525 μs and 650 μs after the valve trigger.展开更多
The surface electric field analysis of the converter valve shield system is a large-scale electrostatic field problem, which is difficult to analyse. The fast multipole boundary element method(FMBEM), which is suitabl...The surface electric field analysis of the converter valve shield system is a large-scale electrostatic field problem, which is difficult to analyse. The fast multipole boundary element method(FMBEM), which is suitable for solving large-scale problems,can accelerate the computation speed and conserve memory. However, the coefficient matrix implicitly formed by using the FMBEM is sometimes ill-conditioned, especially for large-scale problems; thus, the convergence of iteration is poor. In this paper, a fast solver is proposed to improve efficiency. First, an adaptive GMRES(m) with variant restart parameter is adjusted for the Galerkin FMBEM. In addition, the sparse approximate inverse preconditioner is improved, and a new sparsity pattern is proposed for the multiscale problem derived from the converter valve shield system. The numerical results show that the accuracy can meet the engineering requirements compared with the finite element method. Compared with other solvers and preconditioners, the algorithm can achieve a satisfactory convergence rate and reduce the computation time. In addition, a single bridge shield system of ±160 kV converter valve is successfully analysed using the proposed method.展开更多
混合式高压直流（HVDC）断路器是电力电子结合机械开关技术领域新型的高端电力装备,迄今为止其电气试验尚没有可以参照的国际或国家标准。为此,深入分析了混合式高压直流断路器的极限工况,梳理了快速机械开关、主支路阀组以及转移支路...混合式高压直流（HVDC）断路器是电力电子结合机械开关技术领域新型的高端电力装备,迄今为止其电气试验尚没有可以参照的国际或国家标准。为此,深入分析了混合式高压直流断路器的极限工况,梳理了快速机械开关、主支路阀组以及转移支路阀组等关键构成部件的电气应力,提出了能够全面考核整机电磁、热与机械等性能的运行试验和绝缘试验项目,并完成了试验系统的搭建。研究结果表明：所研制的世界首台535 k V电压等级混合式高压直流断路器样机及其关键部件在搭建的试验系统中完成了所提出的各项试验,最大开断电流为25k A,开断时间小于3 ms;针对性提出的试验方案和实现技术能够充分在实验室内考核混合式高压直流断路器的各项指标;试验结果证明了方案的正确性和可行性。该研究为未来混合式高压直流断路器相关试验检测标准的制定奠定了基础。展开更多
基金supported by National Natural Science Foundation of China(No.085JM66502)
文摘In large tokamaks, disruption of high current plasma would damage plasma facing component surfaces （PFCs） or other inner components due to high heat load, electromagnetic force load and runaway electrons. It would also influence the subsequent plasma discharge due to production of impurities during disruptions. So the avoidance and mitigation of disruptions is essential for the next generation of tokamaks, such as ITER. Massive gas injection （MGI） is a promising method of disruption mitigation. A new fast valve has been developed successfully on EAST. The valve can be opened in 0.5 ms, and the duration of open state is largely dependent on the gas pressure and capacitor voltage. The throughput of the valve can be adjusted from 0 mbar·L to 700 mbar·L by changing the capacitor voltage and gas pressure. The response time and throughput of the fast valve can meet the requirement of disruption mitigation on EAST. In the last round campaign of EAST and HT-7 in 2010, the fast valve has operated successfully. He and Ar was used for the disruption mitigation on HT-7. By injecting the proper amount of gas, the current quench rate could be slowed down, and the impurities radiation would be greatly improved. In elongated plasmas of EAST discharges, the experimental data is opposite to that which is expected.
基金supported by National Natural Science Foundation of China(No.51306203)the Natural Science Foundation of Hunan Province(No.2018JJ3592)
文摘A gas injector was designed for the 400 J/pulse prototype of the planar inductive pulsed plasma thruster（IPPT） developed by the National University of Defense Technology（NUDT_IPPTx）.As the gas puff distribution over the coil surface is critical to the NUDT_IPPTx functioning efficiently, a fast ionization gauge was developed to investigate the neutral gas pressure profiles to seek the critical time when the thruster is ignited. The gauge was calibrated for argon by using a capacitance manometer. Time-resolved pressure profiles have been acquired in the condition of the gas puff mass matching with the discharge energy and the drive coil parameters of the NUDT_IPPTx. It is demonstrated that the gas injector can supply a gas puff with a sufficiently steep（dp/dt？≈？770 kPa s-1） leading and trailing edge, and the gas puff can be compressed against the drive coil as expected. The critical ignition moment is considered to appear at some instant between 525 μs and 650 μs after the valve trigger.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2017XS006)
文摘The surface electric field analysis of the converter valve shield system is a large-scale electrostatic field problem, which is difficult to analyse. The fast multipole boundary element method(FMBEM), which is suitable for solving large-scale problems,can accelerate the computation speed and conserve memory. However, the coefficient matrix implicitly formed by using the FMBEM is sometimes ill-conditioned, especially for large-scale problems; thus, the convergence of iteration is poor. In this paper, a fast solver is proposed to improve efficiency. First, an adaptive GMRES(m) with variant restart parameter is adjusted for the Galerkin FMBEM. In addition, the sparse approximate inverse preconditioner is improved, and a new sparsity pattern is proposed for the multiscale problem derived from the converter valve shield system. The numerical results show that the accuracy can meet the engineering requirements compared with the finite element method. Compared with other solvers and preconditioners, the algorithm can achieve a satisfactory convergence rate and reduce the computation time. In addition, a single bridge shield system of ±160 kV converter valve is successfully analysed using the proposed method.
文摘混合式高压直流（HVDC）断路器是电力电子结合机械开关技术领域新型的高端电力装备,迄今为止其电气试验尚没有可以参照的国际或国家标准。为此,深入分析了混合式高压直流断路器的极限工况,梳理了快速机械开关、主支路阀组以及转移支路阀组等关键构成部件的电气应力,提出了能够全面考核整机电磁、热与机械等性能的运行试验和绝缘试验项目,并完成了试验系统的搭建。研究结果表明：所研制的世界首台535 k V电压等级混合式高压直流断路器样机及其关键部件在搭建的试验系统中完成了所提出的各项试验,最大开断电流为25k A,开断时间小于3 ms;针对性提出的试验方案和实现技术能够充分在实验室内考核混合式高压直流断路器的各项指标;试验结果证明了方案的正确性和可行性。该研究为未来混合式高压直流断路器相关试验检测标准的制定奠定了基础。
