基于粒子模拟的一种多路并联磁绝缘传输结构过渡区域的电流损失研究

Current Loss of a Multi-Level Parallel Magnetically Insulated Transmission Structure Based on Particle-in-Cell Simulation

为减小大型脉冲功率装置中磁绝缘传输线复杂的中心汇聚结构产生过渡电流损失,设计了一种新型多路并联竖直三板磁绝缘传输线结构。该磁绝缘传输线结构是在中心汇流区域由并联竖直三板线过渡为单层圆锥结构。经过3维粒子模拟验证,该磁绝缘传输线结构汇流区域的低磁区位于大半径处,可形成良好的磁绝缘。基于空间粒子的相互作用,研究了阴极发射电子和中性气体电离时汇流区域的电流损失。仿真结果表明:中性气体的碰撞电离也是造成电流损失的重要因素之一,当H原子的原子数密度为10^(21)m^(-3)量级时,过渡区域下游阳极的最大电流损失接近2%。此外,计算了脉冲并联数目分别为12,14,16,18,20时,中心汇聚结构电参数的动态变化。计算结果表明,电流损失与并联路数成正比,并联路数增加会降低真空电感,从而增强空间电荷效应,导致阻抗失配加剧,但仍能保持良好的磁绝缘。本文的设计研究结果,有助于深入理解多路并联磁绝缘传输结构的电流损失机理,为磁绝缘的实际应用和下一代脉冲功率装置的发展提供参考。

To reduce the transient current loss caused by the complex central convolute structure of magnetically insulated transmission lines(MITLs)in large pulsed power devices,a new structure of multi-level parallel vertical three-plate MITLs is designed.The structure with the MITLs is a transition from a parallel vertical three-plate lines to a single-layer conical structure in the central convolute region.Using 3D particle-in-cell(PIC)simulation,the low magnetic region of the convolute area of the MITLs structure is located at a large radius,which can form a good magnetic insulation.Based on the interaction of space particles,the current loss in the convolute region is studied when the cathode emits electrons and the neutral gas ionizes.The simulation results show that the collision ionization of neutral gas is also one of the important factors causing current loss of MITLs.When the atomic number density of H atom is 10^(21)m^(-3),the maximum loss current percentage of downstream anode in the transition region is close to 2%.In addition,by calculating the dynamic changes of the electrical parameters of the central convergence structure when the number of parallel feed paths is 12,14,16,18,and 20,respectively,it is found that the current loss is directly proportional to the number of feed channels,and the increase of the number of MITLs parallel channels will reduce the vacuum inductance,thus enhancing the space charge effect,leading to an increase in impedance mismatch,but still maintaining good magnetic insulation.The design and research results of this paper are helpful to deeply understand the current loss mechanism of multi-level parallel magnetically insulated transmission structures,and provide reference for the practical application of magnetically insulated transmission structures and the development of the next generation of pulsed power devices.