电爆炸过程中金属丝阻抗的变化

为了掌握金属丝阻抗的变化规律,通过分压器和罗氏线圈分别测量出电爆炸过程中金属丝上的电压和电流,并由此计算出金属丝阻抗等相关电参数随时间变化的规律;采用F.D.Bennett和A.Hobson模型对金属丝阻抗进行了数值模拟,得到金属丝阻抗随时间的变化规律。实验结果和模拟结果的比较表明:两个模型的模拟结果均在金属丝气化前和部分初始放电电压下有效;当放电时电容器初始电压较大时,能量沉积速度更快,金属丝液化、气化、完全气化所用的时间更短;在金属丝爆炸过程中,金属丝阻抗存在一个最大值。     

水中金属丝电爆炸动力学过程的零维模型

金属丝电爆炸包含丰富的物理内容，近年来国内的实验和理论研究取得了重要进展，理解该过程有助于完善Z箍缩及磁加载等离子体动力学过程的物理建模，校验物性参数。在自相似运动假设条件下，发展了冷启动计算的水中电爆炸丝零维动力学模型。从一维磁流体模型出发，推导了描述丝等离子体膨胀的零维动能方程和内能方程，采用实际气体状态方程和修正的李-莫尔电导率参数作为封闭条件，根据质量守恒及水中激波雨贡纽关系式获得了丝等离子体的边界条件。应用于水中铜丝电爆炸动力学过程和能量转化分析，结果表明：该零维模型的物理假设合理，在一定范围内改变丝直径等参数可产生不同的放电模式，与一维模型及实验结果符合较好，能够为同类实验的优化设计和数据分析提供参考。     

不同介质中电爆炸金属丝断路开关性能的实验研究

进行了不同绝缘介质，如空气、N2、去离子水、变压器油等对电爆炸丝断路开关性能影响的实验研究，结果表明要提高电爆炸金属丝断路开关的性能，除了选用合适的电路参数、金属丝尺寸以外,还必须选用高性能的绝缘介质。     

水中电爆炸的实验研究

利用冲击大电流通过水中的一段金属丝进行水中电爆炸实验 ,通过对水中电爆炸的放电电压、电流波形测量以及高速阴影摄影和扫描摄影 ,记录了冲击波的传播、汽泡增长和等离子体半径的时间特性 ;由不同充电参数的实验 ,得到了一些基本规律。比较了水中电爆炸和空中电爆炸的异同 ,揭示了水中电爆炸存在的放电模式。     

单金属丝电爆炸实验系统研究

概述了实验系统设计的原则，依此研制了小型脉冲功率系统，得到了金属丝电爆炸的实验结果。     

电爆炸丝断路开关性能实验研究

详细研究了初始能量、电爆炸丝截面积和丝长度等参数对含电爆炸丝断路开关的电感储能脉冲功率调节系统输出电流、电压的影响,并将实验结果与数值模拟结果进行了比较,给出了相关的结果。实验结果表明初始能量爆炸丝参数对丝电流、丝电压的影响有一定的规律。     

用金属丝爆炸模拟地下爆炸空腔环境的初步研究

把金属丝和丝周围的砂岩压制样品置于密封的爆室内,利用Mv30-19型大储能电容器组(总储能达232千焦耳)在50千焦耳左右的储能下进行爆炸。实验结果表明,爆室中的金属丝爆炸可以产生足够的温度和压力,即可以产生类似于地下爆炸空腔形成早期的物理化学环境。而且,砂岩样品在爆炸中汽化、熔化至少形成了1克左右的早期玻璃体。 改进装置线路、降低线路电感、选择最佳金属丝参数使其匹配;改进爆炸室结构,并应用磁致收缩效应来提高爆炸丝产生的温度和压力,以产生更多的玻璃体是可能的。     

X-pinch光源及其应用

介绍了X-pinch的基本原理、特点和在Z-pinch物理研究中的部分应用。X-pinch的负载及材料、驱动电流等可以根据需要进行调整，辐射点光源的时间分辨为0．7-2ns,空间分辨为1-5μm，X射线的能量范围从几百电子伏至几千电子伏。利用X-pinch作背光源对金属丝电爆炸进行诊断，可以得到等离子体柱横截面密度等。这些参数对正确理解金属丝阵内爆初级阶段的物理过程有重要意义。     

水中铝丝电爆炸反应的研究

介绍了对金属铝丝在水中电爆炸反应的研究。获得了铝-水反应率和单位质量铝的输入电能的关系曲线。触发lg铝反应所需电能阈值为2kJ,完全反应所需电能为12kJ;反应能量释放率,即反应释放的化学能同输入电能比为1.3。通过改变爆炸丝的截面积,还对放电电流脉冲波形进行了调节,使电容器储能利用率达到了70%。     

电爆炸断路开关综述

叙述了金属导体电爆炸的物理过程，分析了金属导体电爆炸时电阻率的影响因素，从而确定电爆炸断路开关的一般设计原则。     

Similitude in exploding wires

Conditions for similarity have been derived for phenomena involving an exploding wire, propagation of the resulting shock through a fluid, and inelastic deformation or fracture of a structure. This analysis considers the capacitance, voltage and material properties of the exploding wire, as well as the geometry and material properties of the fluid and structure. Model experiments involving large inelastic deformation of aluminum diaphragms agree well with the theoretical predictions. Comparison of deformations due to chemical explosives and exploding wires has been made in an effort to establish an ‘equivalence’ between chemical and electrical explosions. The purpose of this is to provide a basis for using small-scale experiments with exploding wires to predict the performance of larger systems using chemical explosives. The exploding wire appears to provide a precise loading for small-scale structural-model experiments and explosion-forming experiments.     

Particle response to shock waves in solids: dynamic witness plate/PIV method for detonations

Studies using transparent, polymeric witness plates consisting of polydimethlysiloxane (PDMS) have been conducted to measure the output of exploding bridge wire (EBW) detonators and exploding foil initiators (EFI). Polymeric witness plates are utilized to alleviate particle response issues that arise in gaseous flow fields containing shock waves and to allow measurements of shock-induced material velocities to be made using particle image velocimetry (PIV). Quantitative comparisons of velocity profiles across the shock waves in air and in PDMS demonstrate the improved response achieved by the dynamic witness plate method. Schlieren photographs complement the analysis through direct visualization of detonator-induced shock waves in the witness plates.     

Study of cylindrical stress waves generated by exploding wires

An experimental technique utilizing high-pressure gas from an exploding wire is used to load long, hollow, thick-walled cylinders from the inside. Resulting plane-strain cylindrical stress waves are one-dimensional in nature. Asimultaneity of impact is studied with methods of high-speed photography and dynamic photoelasticity.     

Aluminum micro-particles combustion ignited by underwater electrical wire explosion

The results of experiments on the ignition of aluminum micro-particles’ combustion by underwater electrical wire explosion (UEWE) are reported. A compact sub-microsecond timescale duration high-current (240 kA) pulsed power generator was used to explode copper and aluminum wires electrically in different aluminum powder suspensions. The combustion of the aluminum micro-particles was characterized by a target time-of-flight method and optical measurements of the exploding wire and aluminum suspension light emission. It was shown that, by using a proper solution and type of aluminum powder, this method allows aluminum micro-particle combustion in the estimated range of 32–79 % efficiency.     

An examination of dynamic fracture under biaxial-strain conditions

An experiment to investigate the influence of biaxial strain on the dynamic fracture of metals is outlined. A hollow cylindrical specimen is loaded on the inner diameter by a polyethylene-coated exploding wire which results in a circumferential spallation pattern. Prior to fracture, the spall surface undergoes biaxial deformation with a total hoop strain of the same order of magnitude as the total radial strain. This is in contrast to earlier studies in which fracture induced by stress waves was examined in experiments which are characterized by uniaxial-strain conditions. Comparing the results of the two configurations, it can be shown that the maximum principal-stress history required to cause fracture is the same in both cases, although the stresses normal to the fracture surface are quite different. High-speed photographs of the coated exploding wires and dynamic-flash X-rays of the specimens are included to demonstrate the axisymmetry of both the loading and the spall phenomenon.     

球面激波在固壁的马赫反射

本文对金属丝电爆炸产生球面激波在固壁上的马赫反射作了研究。由高速纹影摄影系统将反射图像拍摄下来,从而测量出马赫杆在壁面的马赫数,进而得到超压以及三波点迹线,实验结果与我们的数值计算结果作了比较,二者比较吻合。     

实现材料高应变率拉伸加载的爆炸膨胀环技术

设计了新型的爆炸膨胀环实验加载装置,加载装置中采用爆炸丝线起爆方式,避免了传统装置中对碰爆轰波加载时的应力不均匀性。利用新型的爆炸膨胀环实验技术研究了无氧铜材料的动态性能,利用激光位移干涉仪测量了试样环的径向速度历史,处理数据获得了无氧铜材料的流动应力-塑性应变-应变率的关系,为进一步利用爆炸膨胀环实验技术研究材料在高应变率拉伸加载时的本构关系奠定了基础。     

Electrical conductivity of warm dense tungsten

The electrical conductivity of warm dense tungsten plasma has been investigated successfully by a linear mixture rule considering various interactions of electrons with electrons, atoms, and ions. The plasma composition is calculated by the nonideal Saha equation. The interesting regime for tungsten plasma spans from weakly coupled and nondegenerate regime to strongly coupled and partial degenerate state. The electrical conductivity calculated is in reasonable agreement with the exploding wire experiments and other theoretical models. The present result demonstrates that the theoretical model is valid for the electrical conductivity of tungsten plasma in the warm dense matter regime.