共查询到19条相似文献,搜索用时 375 毫秒
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微小空间碎片超高速撞击航天器表面, 能够抛射出高密度的等离子体云团, 如果撞击发生在航天器的高充电表面或带电部件等敏感区域, 撞击等离子体将会诱发放电, 该机制已经引起了广泛的关注, 但是相关研究还十分欠缺. 本文利用等离子体驱动微小碎片加速器加速200 μm的微粒, 通过模拟实验开展微小空间碎片撞击诱发放电的研究, 获得了典型的实验结果, 对撞击诱发放电信号的特征进行了分析.
关键词:
微小空间碎片
撞击诱发放电 相似文献
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超高速撞击实验中,通过对撞击发光信号的监测,利用光谱分析法测量超高速微粒撞击形成等离子体的温度和密度是最有效的方法,也是深入研究微小空间碎片撞击诱发放电效应的基础.国内外相关机构已利用该方法对毫米以上微粒撞击等离子体的参数进行了监测,但是毫米以下微粒撞击发光信号的监测难度更大,相关研究还未见报道.本文在等离子体驱动微小碎片加速器上对百微米级微粒超高速撞击的发光信号进行了监测,对该撞击发光信号以及撞击诱发放电过程中发光的基本特征进行了分析,并提出了利用撞击发光信号对微粒速度进行测量的方法. 相似文献
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等离子体电磁加速器可产生高速度、高密度等离子体射流而广泛应用于核物理、天体物理等领域.本文通过光电二极管、磁探头研究了不同放电电流和初始气压条件下等离子体在平行轨道加速器内的轴向运动特性.通过电流截断的方法,采用冲击摆测量了首次等离子体射流的动量.平行轨道加速器驱动电源由14级脉冲形成网络组成,每级电容为1.5μF,每级电感约为300 nH,得到振荡衰减型方波的电流波形.实验发现,电流过零时,轨道起始处一般会发生二次击穿,并形成二次轴向运动的等离子体.放电电流为10—55 kA、初始气压为200—1000 Pa时,等离子体的轴向速度为8—25 km/s.实验获得的等离子体的运动速度为雪犁模型理论结果的60%—80%,这主要是理论模型忽略了电极表面对电弧的黏滞阻力以及电极烧蚀引起的质量增加.等离子体动量与电流的平方随时间的积分成正比.放电电流为21-51.6 kA时,首次等离子体射流的动量为1.49—9.88 g·m/s.等离子体运动过程中除了受到洛伦兹力外,还会受到电极表面的黏滞阻力,造成等离子体动量约为理论结果的75%. 相似文献
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对圆柱形阳极层霍尔加速器内的放电等离子体运用二维质点网格方法(particle in cell)进行数值模拟,用蒙特卡罗碰撞方法处理带电粒子与中性粒子之间的碰撞. 得到了放电通道内离子与电子的分布以及离子流的运动,并且对出口外侧的能量分布进行了统计. 结果发现圆柱形阳极层等离子体加速器的磁场对电子有明显的约束作用,电子集中于阳极附近很小的区域内. 由于电磁场的特殊分布,离子流呈现出双峰式的分布. 离子能量范围从放电电压的20%到接近放电电压,平均能量在放电电压的40%—50%之间.
关键词:
质点网格方法
蒙特卡罗碰撞
数值模拟
阳极层霍尔等离子体加速器 相似文献
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The pioneering investigation of the behavior of a current bridge in a coaxial accelerator with pulsed delivery of a working
gas liberated from titanium hydride by an electrical discharge is reported. A new method to trace the motion of the current
bridge using LEDs is suggested. The behavior of the current bridge in accelerators with axial and radial gas injection is
studied. The parameters of an accelerator generating a pure plasma jet with a high kinetic energy (such as the size and polarity
of electrodes, gas flow direction, and time delay between the delivery of the gas to the accelerator and its ionization) are
optimized. The applicability of an electrodynamic model to this type of accelerator is discussed. Good agreement between experimental
data and calculation results is obtained. 相似文献
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B. I. Reznikov S. V. Bobashev B. G. Zhukov R. O. Kurakin S. A. Ponyaev S. I. Rozov 《Technical Physics》2014,59(4):499-502
The concept of an effective erosion coefficient, which takes into account the capture and entrainment in motion (by accelerated plasma) of only part of the erosion mass lost by rail accelerator electrodes, is introduced to describe the plasma acceleration dynamics in the channel of an electromagnetic rail accelerator. This parameter is determined from a comparison of the experimental and calculated plasma velocities at the stage of velocity saturation. The plasma velocity is calculated using a model that takes into account the pressure force of a shock-compressed gas and the deceleration force that appears during the capture of the erosion mass by a plasma piston. The ratio of the captured mass to the mass lost by the electrodes is found to depend on the current; for copper, this ratio is 1/4–2/3. The effective erosion coefficient is 0.6–0.7 mg/C at a current of ~40 kA. 相似文献
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针对空间碎片超高速撞击充气压力容器问题,应用非线性动力学分析软件AUTODYN-2D,采用SPH方法对碎片云在高压气体中的运动特性进行了数值模拟研究。在建模过程中,分析比较了材料状态方程对数值模拟结果的影响,并通过与实验结果的比较,选取了适合该问题的状态方程,验证了数值模拟方法的有效性。结果表明:由于容器内压气体的存在,碎片云运动发生减速,并且碎片云的轴向扩展速度相对于碎片云的径向扩展速度减速较慢;高速撞击产生的碎片云与容器内的高压气体发生了强烈的相互作用,碎片云尖端产生的钉状物及高压气体中产生的冲击波是控制容器在撞击后发生进一步破坏的两个重要因素。 相似文献
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强流相对论电子束二极管阴阳极等离子体的形成和漂移,是二极管工作状态研究的重要组成部分。根据Child-Langmuir定律和二极管导流系数,结合二极管阴极电子发射面积的变化模型,给出了二极管阴阳极等离子体漂移所导致的阴阳极间隙闭合速度。 相似文献
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限流沿对撞壁射流近壁区混合过程影响的实验研究(二) 总被引:3,自引:0,他引:3
1前言本文的第一部分分析了射流气体撞击限流沿后的发展过程以及射流入射角、限流沿高度等对二次射流气体发展情况的影响。本文将详细分析射流气体撞击限流沿后所形成的二次射流的速度和浓度的分布规律,并利用标量耗散率描述了射流气体的混合情况。众所周知,混合是扩散火焰燃烧速度的控制因素。通常扩散燃烧区内的温度足以使燃烧化学反应瞬间完成,因此燃烧时间完全取决于混合时间,即燃烧反应的速率由混合速率来控制。RW.Bilger等[1]认为扩散燃烧反应只有当完全达到分子级混合时才发生,他们在研究中利用标量耗散率概念来描述分子级混… 相似文献
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Temporal evolution of the floating potential of the laser-blow-off plasma plume and its variation with experimental conditions is studied using a triple Langmuir probe. Findings indicate that oscillatory structures are formed in the trailing portion of the plume in vacuum and their amplitudes vary with axial distance, laser fluence and ambient gas pressure. Spectral analysis suggests that an acoustic wave of specific frequency and phase velocity propagates. The neutral density gradient in the laser-blow-off plasma plume and its equilibration might be responsible for the above phenomenon. 相似文献
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A theoretical analysis of the effect of velocity radial nonuniformity on nonstationary gas-solid adsorption processes in the column apparatuses is presented. The average concentration model, where the radial velocity component in the gas phase is equal to zero (in cases of a constant velocity radial nonuniformity along the column height), is used in the cases of an axial modification of the radial nonuniformity of the axial velocity components in the gas phase. The use of experimental data, for average concentrations in the gas phase at the column end, for a concrete process (physical or chemical adsorption), permits obtaining the gas phase model parameters related with the radial nonuniformity of the velocity. These parameter values allow using the average concentration model for modeling different adsorption processes. 相似文献
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During investigations carried out with hydrogen as the working gas on the coaxial accelerator, a retrograde shock wave front was observed in streak photographs, taken for velocity and trapping fraction measurements of the snowplough. The velocity of this wave front was found to be 8 × 104 m/s which falls in the category of strong ionizing shocks. In such cases the life of the pinch was found to be longer and this is because such waves ionize more gas and increase the duration of the low-β plasma in the interelectrode space. 相似文献
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Mathuthu M. Zengeni T.G. Gholap A.V. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1997,25(6):1382-1388
A simplified theory for preliminary design of plasma focus devices that starts at the breakdown phase is proposed. For best focus, it is shown that the model can be used to predict the values of the inner and outer electrode radius, inner electrode length, gas pressure, and charging voltage that give minimum possible pinch radius. The theoretical results agree with experimental observations. The model shows that of these parameters, inner electrode length, inner and outer electrode radii play a significant role. An optimum pinch radius ratio of 0.05 to 0.40 was realized. Test results show that the focus strength is dependent on the breakdown conditions via the initial and final velocities of the current sheath during the radial collapse phase and the axial rundown phase. The final axial velocity determines the initial inward radial velocity. Results for a test design are presented 相似文献