喷射等离子体触发气体开关形成双流注的物理机制与参数调控

The low working coefficient, low jitter triggered gas switch is the one of the key factors restricting the electrical pulse superposition with high efficiency, the trigger breakdown time delay and its jitter is mainly decided by the breakdown process, the plasma jet triggered gas switch has the potential to meet this demand. However, the breakdown of the plasma jet triggered gas switch can form a single or head-on collision streamers. As the formation and conversion mechanism of the head-on collision streamers from a single streamer is still unclear, the understanding of gas switch breakdown mechanism is limited and the developments of the low jitter trigger technologies is restricted. To solve the problem, the project will be proceeded from a new perspective, the critical physical parameters of the head-on collision streamers formation, and focus on the core problem, the formation mechanism of the second streamer at the head of the plasma jet. From the two aspects including dynamic characteristics of the plasma jet and its physical effects, solves basic problems including: the initial effective electrons formation mechanism and its developing performance at the head of the plasma jet, building a physical model to describe the second streamer formation process and optimizing the trigger performance by adjusting the plasma jet parameters. The prospective achievements could further reveal the critical theory criterion and the formation mechanism of the head-on collision streamers induced by plasma jet, promote the development of the short gas gap streamer discharge theory, and provide supports and references for the research of the low working coefficient, low jitter triggered gas switch.

低工作系数、低抖动触发气体开关是实现电脉冲高效叠加的关键因素之一，开关击穿过程决定触发抖动，采用喷射等离子体有望实现开关低工作系数下低抖动触发。然而，喷射等离子体触发可形成单/双流注放电过程，针对单/双流注转换的临界物理参数以及第二流注形成的物理机制尚不清楚，限制了人们对开关击穿机理的认识，制约了开关触发技术的发展。针对这一问题，本项目拟从喷射等离子体触发气体开关形成双流注的临界物理条件这一新角度，抓住影响等离子体前沿面上形成第二流注的关键因素这一核心问题，从等离子体的动态特性与物理效应着手，研究等离子体前沿面上形成初始有效电子的物理机制及其对电场分布的影响，建立描述第二流注形成的物理模型，对等离子体参数进行调控，优化开关的触发特性。通过研究，可揭示等离子体作用下双流注形成的临界理论判据和物理机制，完善短间隙流注放电理论，为低工作系数、低抖动触发气体开关研制提供理论基础和科学依据。

低工作系数、低抖动触发气体开关是实现FLTD电脉冲高效叠加的关键因素之一，认识气体开关触发导通过程，探索新的触发方式和结构，对于提高FLTD气体开关工作可靠性具有重要意义。..本项目针对气体开关击穿过程展开深入研究，建立了单、双波长马赫-曾激光干涉系统对击穿过程进行诊断，并形成了等离子体参数计算方法；采用多分幅高速相机对放电动态演化过程进行分析，获得了影响气体开关击穿过程的关键因素；发现等离子体的动态过程对于流注形成和发展有重要作用，是决定流注形成的关键因素；通过调控等离子体参数，获得了单、双流注形成和发展特性，实现了对流注形成过程的调控；在此基础上完成了存在双流注作用下的流注击穿理论模型建立，分析获得了流注放电过程中等离子体对开关击穿过程的影响因素并对其进行量化，从而加深对气体开关击穿过程的理解，为降低开关工作系数和触发抖动提供理论分析基础。下一步将继续考虑空间光电离、电子崩对流注头部区域电子层的贡献，尝试采用流体方法开展双流注形成过程的理论模拟研究。