重复频率磁延迟伪火花开关放电特性及机理研究

High repetitive frequency is one of the development trends of pulsed power technology. The repetitive frequency pulsed power devices presents the urgent demand for the switch technology. Semiconductor switch, magnetic switch, thyratron and pseudospark switch have their own advantages respectively, but they could not satisfy all the requirements of repetitive operation mode at the same time. By serially connecting pseudospark and magnetic switch, the current rising time of magnetically delayed pseudospark is delayed which results in a substantially reduced switching loss and it is especially suitable for the repetitive application. The research on this new type switch is still in the conceptual and preliminary experimental stage at home and abroad. The conduction and quenching mechanism, triggering characteristics, dielectric recovery, electrode erosion characteristics and insulation structure design methods of magnetically delayed pseudospark have not been studied. In view of this situation, this project establishes single-pulse, double-pulse and repetitive frequency experimental platforms and the joint simulation of particle and circuit method is proposed. With the experimental and simulation method, the influence of the type and parameters of magnetic switch, trigger and pseudospark switch on the switching and quenching process, delay and jitter, insulation recovery, electrode erosion and insulation structure design methods will be studied. The aims of this project are to grasp the discharge characteristics, clarify discharge mechanism and propose the insulation performance control method and design technique. This project will lay the foundation for the magnetically delayed pseudospark switch technology.

高重复频率是脉冲功率技术发展趋势之一，重复频率脉冲功率装置对开关技术提出了迫切需求。半导体开关、磁开关、闸流管和伪火花开关各有优点，但难以同时满足重复频率运行对开关各方面的要求。磁延迟伪火花开关通过在伪火花开关上串联磁开关，延迟开关电流的上升时刻，大幅降低开关导通损耗，尤为适用于重复频率应用。国内外对其研究尚处于概念和初步实验阶段，串联磁开关后开关的导通和淬灭机理、触发特性、绝缘恢复和电极烧蚀特性、绝缘结构设计方法还未深入研究。针对该现状，本项目建立磁延迟伪火花开关单次、双脉冲和重频实验平台，提出粒子模拟和外电路联合仿真方法，研究磁开关、触发器和伪火花开关的型式和参数对开关导通和淬灭过程、时延和抖动、绝缘恢复、电极烧蚀的影响，以及开关绝缘结构设计方法，以期掌握开关的放电特性，阐明其放电机理，提出绝缘设计、参数配合和性能调控方法，为磁延迟伪火花开关技术奠定基础。

重复频率脉冲功率技术对开关提出了较高的要求。伪火花开关作为一种特殊的低气压放电开关，在重复频率脉冲功率装置中有很好的应用前景。本项目提出将磁开关与伪火花开关串联来降低开关在导通阶段的损耗，这种开关也被称作磁延迟伪火花开关。项目建立了磁延迟伪火花开关电学、光学诊断实验平台，并搭建粒子仿真模型，研究了磁延迟伪火花开关的工作特性。此外，本项目研制了一种小型化伪火花开关。本项目得到的结论如下。首先，磁开关的加入显著延长了伪火花放电中空心阴极阶段的持续时间，使得回路电流的快速上升滞后于开关两端电压的快速下降，从而有效减小了伪火花开关的导通损耗。当磁芯数量增加时，伪火花开关的导通损耗逐渐降低。本项目也研究了伪火花开关的电流淬灭现象，发现磁开关可以有效抑制电流淬灭。第二，在研究磁延迟伪火花开关的触发工作特性时，本项目研制了基于雪崩三极管的改进型辅助触发多管串联Marx电路，以及基于BaTiO3的触发单元，发现高电压、快前沿、低抖动的触发脉冲可以显著减小伪火花开关的触发时延和抖动；磁开关对伪火花开关的触发特性几乎没有影响。第三，项目研制了成品化小型低抖动封闭式双间隙多通道伪火花开关，具有45 kV的耐压，20 kA的通流，42 ns的触发时延和小于1 ns的触发抖动。利用双脉冲实验平台测试了该伪火花开关的绝缘恢复特性，发现该开关可以在最高充电电压40 kV下，以4 kHz的等效重复频率进行工作。最后观察发现将伪火花开关与磁开关串联可以显著减小伪火花开关电极的表面烧蚀。综上所述，项目阐明了磁延迟伪火花开关的导通机理，获得了磁开关对伪火花开关放电特性、电流淬灭、电极烧蚀的影响规律，研制了小型化封闭式伪火花开关，并将其用于国家大科学设施CZ-15装置的触发系统，表现出优异的性能。