Al丝物理状态调控及对芯晕演化特性的影响

基于快直线脉冲变压器(FLTD)平台开展了数十kA电流下Al单丝芯晕演化特性研究，实验发现丝过早发生电压击穿会减少丝芯的能量沉积，而晕等离子体的迅速发展将约束丝芯的进一步膨胀，降低丝芯膨胀速度。通过调整负载两端的初始电压、丝长及增加闪络开关等手段，抑制了Al丝的过早击穿，增加了早期能量沉积，获得了不同的丝芯物理状态（部分气化或完全气化）。Al丝的气化提高了丝芯膨胀速度，最高达11~14 km/s，晕等离子体发展缓慢，延缓了边界处不稳定性的出现，降低了后期m=0的发展速度。FLTD负极性输出时，Al丝沿轴向的极性效应更加明显，靠近阴极处丝芯膨胀慢，边界处晕等离子体密度高，不稳定性的发展速度快。     

百千安电流下的单丝Z箍缩实验研究

为更深层次理解Z箍缩基本物理过程，认识单丝早期演化对丝阵后续内爆过程产生的影响，基于百千安直线脉冲变压器（FLTD）平台开展了不同材料（钨丝、镀膜钨丝和铝丝）单丝Z箍缩实验研究，实验获得了单丝演化过程的双分幅激光阴影和干涉图像。实验发现：初始直径相同（15 μm）的条件下，铝丝核的膨胀速度比钨丝核的快，在电流开始一段时间内，铝丝核沿轴向呈均匀膨胀，而钨丝核因电极效应沿轴向膨胀不均；镀膜钨丝（15 μm W+2 μm Polyimide）核的膨胀速度远大于钨丝核的，甚至高于铝丝核的，同时镀膜还降低了消融等离子体不稳定性的发展速度。     

直线脉冲变压器技术回顾与展望

直线脉冲变压器是近年来发展最迅速的高功率脉冲驱动源.介绍了快放电直线脉冲变压器的应用前景、工作原理,回顾了直线脉冲变压器的技术发展历程,分析了不同时期的结构特点,阐述了开关、触发系统、磁芯等关键技术研究现状和今后研究重点.最后总结了直线脉冲变压器发展动向及可能涉及的相关技术.     

Study on Performance Parameters of the Plasma Source for a Short-Conduction-Time Plasma Opening Switch

Plasma source performance parameters,including plasma ejection density and velocity,greatly affect the operation of a short-conduction-time plasma opening switch(POS).In this paper,the plasma source used in the POS of Qiangguang I generator is chosen as the study object.At first the POS working process is analyzed.The result shows that the opening performance of the POS can be improved by increasing the plasma ejection velocity and decreasing the plasma density.The influence of the cable plasma gun structure and number on the plasma ejection parameters is experimentally investigated with two charge collectors.Finally a semi-empirical model is proposed to describe the experimental phenomenon.     

Dynamic Model for the Z Accelerator Vacuum Section Based on Transmission Line Code

The transmission-line-circuit model of the Z accelerator, developed originally by W. A. STYGAR, P. A. CORCORAN, et al., is revised. The revised model uses diffe...     

兆安级电流下Al丝阵的芯晕结构抑制研究

为了抑制丝阵Z箍缩中金属丝在电流早期电爆炸形成的芯晕结构，基于强光一号加速器，利用二级丝阵负载开展了Al丝阵早期物理状态的调控研究。通过陡化预脉冲和调整二级丝阵的参数，实现了负载Al丝的全部汽化，抑制了芯晕结构的产生，气态Al丝芯的平均直径约为1.80 mm，且沿轴向均匀分布，降低了丝阵消融引起的初始不稳定性。若丝长度和直径保持不变，反转型丝阵的关断时间主要取决于Al丝的丝数；反转型丝阵关断后，气态丝芯在主电流脉冲作用下迅速电离并开始内爆，磁瑞丽泰勒不稳定性迅速发展，内爆等离子体流沿轴向呈周期性调制分布，调制波长约为650 μm。Al丝阵初始状态的改变，有效抑制了丝的消融过程，消除了先驱等离子体，在内爆后期降低了拖尾质量，提高了箍缩品质。     

用于Z箍缩诊断装置的快阀研制

Z箍缩实验滞止后期负载产生的微小碎片及其他飞溅物质会污染Z箍缩诊断系统内的光学器件,本文研制了一种基于电磁感应原理的快阀,其可用于遮断微小碎片及其他飞溅物质。根据能量守恒和电路方程,计算了快阀的运动速度、遮断时间及线圈放电电流等参数,并利用实验测量获得快阀运动速度为19 m/s,遮断时刻时间抖动为85 μs,实验测量与计算结果较为吻合。     

双平行电极场畸变气体火花开关电极优化与实验研究

为适应新型低电感电容,笔者优化设计了应用于电缆绕组型直线脉冲变压器的新型双平行电极场畸变气体火花开关。对触发电极处于主放电通道和未处于主放电通道的两种电极结构进行了仿真模拟,通过模拟发现不同触发电极位置对开关电场分布无明显影响。分别对触发电极不同位置的场畸变火花开关进行实验,开展了不同电极结构的静态耐压、触发延迟实验。实验数据表明,触发电极处于主放电通道上时,开关的静态特性和触发特性较好。     

Optical Diagnostics of Multi-Gap Gas Switches for Linear Transformer Drivers

The trigger characteristics of a multi-gap gas switch with double insulating layers,a square-groove electrode supporter and a UV pre-ionizing structure are investigated aided by a high sensitivity fiber-bundle array detector, a UV fiber detector, and a framing camera, in addition to standard electrical diagnostics. The fiber-bundle-array detector is used to track the turn-on sequence of each electrode gap at a timing precision of 0.6 ns. Each fiber bundle, including five fibers with different azimuth angles, aims at the whole emitting area of each electrode gap and is fed to a photomultiplier tube. The UV fiber detector with a spectrum response of 260-320 nm,including a fused-quartz fiber of 200 μm in diameter and a solar-blinded photomultiplier tube, is adopted to study the effect of UV pre-ionizing on trigger characteristics. The framing camera,with a capacity of 4 frames per shot and an exposure time of 5 ns, is employed to capture the evolution of channel arcs. Based on the turn-on light signal of each electrode gap, the breakdown delay is divided into statistical delay and formative delay. A decrease in both of them, a smaller switch jitter and more channel arcs are observed with lower gas pressure. An increase in trigger voltage can reduce the statistical delay and its jitter, while higher trigger voltage has a relatively small influence on the formative delay and the number of channel arcs. With the UV pre-ionizing structure at 0.24 MPa gas pressure and 60 kV trigger voltage, the statistical delay and its jitter can be reduced by 1.8 ns and 0.67 ns, while the formative delay and its jitter can only be reduced by 0.5 ns and 0.25 ns.     

γ射线二极管寿命提升关键技术实验研究

本文通过分析γ射线二极管的物理过程,对二极管的阴阳极材料和结构进行了改进,并在强光一号装置上进行了实验验证。实验结果表明,通过采用深槽结构的黄铜阴极和多层阳极靶可显著降低强光一号装置二极管的阴极烧蚀、溅射沉积污染及阳极的热-力学损伤。改进后的阴极至少可重复使用3发次,阳极至少可重复使用4发次。实验结果为建设中的大面积脉冲γ射线辐射装置二极管的研制和实验效率提升提供了新技术途径。