FLTD气体火花开关自放电诱发机理和概率模型

Fast Linear Transformer Driver (FLTD) is an economic and effective technical routine for constructing high-current high-voltage pulsed power drivers, but the pre-fire problem of gas switches is a bottleneck restricting the stability and reliability of FLTD. Firstly, electrode erosion properties, including the surface morphology such as surface protrusion and etch pit and erosion products such as particles and powder, will be investigated under the typical working condition of FLTD (10-40kA current with a 50-300ns rising time, at ±100kV), and the influence of current parameters and electrode materials on the statistic properties including surface roughness and erosion particle size, will be studied. The ultrasonic probe, high speed camera and electrostatic probe will be employed to diagnose the charging, movement and micro-discharge of eroded micro-particle as well as its time sequence with switch pre-firing. The mechanism of eroded morphology and erosion micro-particles inducing switch pre-fire will be investigated and the influence on pre-fire probability will be also studied. The mathematic relation between the group behavior of a system including multiple gas switches in series and parallel and the individual behavior of a single gas switch will be studied by the Monte Carl simulation method, and then the enhancement of the effect in multi-switches system from random factors and switch difference is investigated. Afterwards, the influence of charge speed and the switch arrangement, including being in series and parallel, on the pre-fire probability of a system is studied. At last, a model for pre-fire probability calculation of a large scale system with multiple gas witches will be established. The result of this project can provide an overall understanding of pre-fire mechanisms in FLTD switches. Therefore, the project has significant scientific importance and application value.

开关自放电是制约快直线变压器驱动源（FLTD）等多模块叠加型脉冲功率装置稳定、可靠性的瓶颈之一。项目拟研究FLTD快脉冲大电流放电条件下电极熔蚀产生的晶须、蚀坑等微形貌和产物颗粒的尺寸、形态，掌握放电电流、电极材料对熔蚀形貌和产物颗粒统计特性的影响规律；拟通过声光电联合诊断的方法研究熔蚀颗粒的荷电、运动、微放电行为及其与开关自放电的时序关系，阐明电极形貌、熔蚀颗粒诱发开关自放电的机制及对自放电概率统计特性的影响规律；拟采用蒙特卡罗模拟方法获得多开关系统自放电“群体行为”与单开关“个体行为”的概率关系，并研究开关差异性、随机诱因等在系统中的“放大效应”，然后实验研究开关排布方式（级联、并联）和电压作用时间对系统自放电概率的影响规律，最终建立大规模开关串/并联系统自放电的概率模型。项目研究结果可较全面地认识FLTD气体开关自放电产生机理及概率统计规律，具有重要科学意义和应用价值。

开关自放电是制约快直线变压器驱动源等多模块叠加型脉冲功率装置稳定、可靠性的瓶颈之一。项目首先研究了FLTD快脉冲大电流放电条件下电极熔蚀产生的晶须、蚀坑等微形貌和产物颗粒的尺寸、形态，掌握了放电电流、电极材料对熔蚀形貌和产物颗粒的影响，发现FLTD典型放电条件下，开关烧蚀导致电极表面粗糙度增加值几十微米，并会产生液滴溅射、固体颗粒等，并获得了电极表面粗糙度、蚀坑直径、蚀坑深度等参数和电流脉冲参数、电极参数的量化关系模型。阐明了气体火花开关自放电诱发机制，发现开关自放电是由于电极熔蚀产物颗粒运动、悬浮电极电位漂移、熔蚀产物导致沿面提前非预期闪络等方面共同诱发产生的，研究并掌握了开关工作系数、电极形状、气压、电极尺寸等因素对开关自放电概率、放电延时和抖动等的影响规律。研究并掌握了三电极场畸变气体开关和六间隙多通道气体开关的不同放电条件下的自放电特性，发现其在65%~80%工作系数下的放电延时在几十ns量级、抖动在3ns左右、自放电概率在0.2%~1.2%范围。发现开关自放电概率直接决定于其放电条件、开关结构、中间电极悬浮状态等因素。多开关串并联时，其自放电事件相互独立，多开关自放电概率随开关数量呈显著的增大趋势，最后建立了多开关自放电概率的计算模型。研究结果可较全面地认识FLTD气体开关自放电产生机理及概率统计规律，具有重要科学意义和应用价值。