共查询到17条相似文献,搜索用时 46 毫秒
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分析了磁重联对晕等离子体加速和能量平衡过程的影响。分析表明晕等离子体向轴心的加速过程分为两个阶段:第一阶段晕等离子体在磁压或热压(依赖于丝数)作用下向轴心运动;第二阶段晕等离子体由于磁重联过程被加速到阿尔芬速度,并到达轴心形成先驱等离子体。估算表明重联层的厚度与离子的惯性长度具有相同的数量级,电流片内电子运动和离子的运动是解耦合的。在内爆滞止阶段电荷分离产生强的径向电场,这个电场将磁能转化为等离子体轴向(z方向)动能,内爆动能和轴向动能共同转化为X射线辐射能,以此解释了X射线能量大于内爆动能这一观测结果。分析了磁重联电磁脉冲的性质,对于1 MA驱动条件,电磁脉冲的总能量可达kJ量级。 相似文献
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讨论了Z箍缩内爆产生的低频电磁脉冲的辐射特性. Z箍缩驱动金属丝阵或固体套筒高速内爆,部分磁能通过与负载的运动耦合而向外辐射. 理论结果表明,电磁脉冲辐射功率由电流和内爆轨迹共同决定. 在中国工程物理研究院流体物理研究所的初级实验平台上开展了负载电流为7 MA,10%–90%上升时间65 ns的丝阵Z箍缩实验,根据实验测得的电流和内爆轨迹得到了电磁脉冲的辐射功率和频谱. 电磁脉冲峰值功率约为1 GW,能量约为0.5 J,能量转换效率约为10-7;峰值频率位于20–70 MHz,具有较宽的辐射频谱. 电磁脉冲辐射参数远小于软X射线辐射参数(峰值功率为50 TW,能量为0.5 MJ). 在弱相对论条件下,电磁脉冲辐射功率近似地正比于电流的6次方,随电流急剧增大. 软X射线辐射是丝阵Z箍缩过程中的主要能量转换形式,本文的研究结论表明,在更高的驱动电流下,电磁脉冲辐射将提供另一种重要的能量转换途径,势必会对诊断设备造成严重影响;此外,这类强电磁脉冲在其他领域也具有潜在的应用价值.
关键词:
Z箍缩
内爆
电磁脉冲 相似文献
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目的,快过程Z箍缩内爆等离子体可以把储存的脉冲功率加速器内155的电能转化为大能量、高功率的X射线源,美国Sandia实验室的Z装置已经产生了总能量为1.8MJ、功率为290TW和黑腔湿度超过200eV的X射线源,这些进展正在用于惯性约束聚变(ICF)实验研究,并对它的后续装置X-1正在进行概念性设计,文章概要地叙述了Sandia实验室近五年来在Z装置上进行Z箍缩实验所取得的进展。 相似文献
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在"强光一号"装置上, 利用微型磁探针系统测量了钨丝阵负载内部的消融等离子体携带的电流, 对比了有无泡沫柱两种负载条件下内部电流分布的差异, 获得了稳定可靠的实验数据. 实验中使用了由42 根4.2 μm 钨丝组成的直径12 mm 的丝阵负载, 脉冲电流峰值为1.34 MA, 上升时间约70 ns. 结果表明: 在电流放电开始约20 ns 后, 半径3.2 mm 处的磁探针有明显的信号输出, 随后的20 ns 内, 内部等离子体分流比迅速上升至约20%, 并在30—40 ns 内基本保持稳定. 丝阵加载泡沫柱后, 内部电流值在Z 箍缩前期没有明显变化. 相似文献
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利用二维辐射磁流体程序模拟了钨丝阵Z箍缩等离子体腊肠不稳定性的演化:分析了存在不稳定性与没有不稳定性条件下等离子体内爆的差异;研究了不同初始密度扰动对x射线输出 功率和能量的影响.数值结果表明,在一定初始密度扰动范围内,这种不稳定性对x射线输 出的总能量影响不显著,但对x射线功率随时间变化的曲线有明显的影响.此外,还探讨了Z 箍缩等离子体数值模拟中低密度区的数值处理对数值结果的影响.
关键词:
Z箍缩
腊肠不稳定性
数值模拟 相似文献
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A class of processes involving magnetic field reconnection, in collisionless plasmas and magnetic configurations where the field undergoes a finite change of direction, is investigated. Reconnecting modes that rely on the effects of electron Landau resonance and density gradient for their excitation are found to require the analytical or numerical treatment of four consecutive asymptotic regions. The influence of finite electron temperature gradient in the region where the effects of electron Landau resonance prevail, and the convection of energy toward the region where ion Landau resonance is dominant tend to dampen these modes. Conversely, significant distortions of the ion distribution can follow their excitation. The relevance of the obtained results to experimental observations on laboratory plasmas and in space physics is discussed. Different processes are involved with magnetic reconnection in magnetic configurations where the field does not have appreciable shear but has a neutral surface on which it vanishes. 相似文献
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Quanming Lu 《中国物理 B》2022,31(8):89401-089401
Magnetic reconnection underlies the physical mechanism of explosive phenomena in the solar atmosphere and planetary magnetospheres, where plasma is usually collisionless. In the standard model of collisionless magnetic reconnection, the diffusion region consists of two substructures: an electron diffusion region is embedded in an ion diffusion region, in which their scales are based on the electron and ion inertial lengths. In the ion diffusion region, ions are unfrozen in the magnetic fields while electrons are magnetized. The resulted Hall effect from the different motions between ions and electrons leads to the production of the in-plane currents, and then generates the quadrupolar structure of out-of-plane magnetic field. In the electron diffusion region, even electrons become unfrozen in the magnetic fields, and the reconnection electric field is contributed by the off-diagonal electron pressure terms in the generalized Ohm's law. The reconnection rate is insensitive to the specific mechanism to break the frozen-in condition, and is on the order of 0.1. In recent years, the launching of Cluster, THEMIS, MMS, and other spacecraft has provided us opportunities to study collisionless magnetic reconnection in the Earth's magnetosphere, and to verify and extend more insights on the standard model of collisionless magnetic reconnection. In this paper, we will review what we have learned beyond the standard model with the help of observations from these spacecraft as well as kinetic simulations. 相似文献
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“阳”加速器Z-Pinch实验中负载方案的分析 总被引:8,自引:6,他引:2
对“阳”加速器(1.2MV,1.5MA,120ns)上开展Z箍缩(Z-Pinch)内爆等离子体实验产生强X光源的负载设计进行了基本的物理分析,在此基础上给出负载的结构尺寸、气体种类、密度和相关的参数。这些结果对物理问题的分析是有帮助的. 相似文献
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An endogenous reconnection process involves a driving factor that lays inside the layer where a drastic change of magnetic field topology occurs. A process of this kind is shown to take place when an electron temperature gradient is present in a magnetically confined plasma and the evolving electron temperature fluctuations are anisotropic. The width of the reconnecting layer remains significant even when large macroscopic distances are considered. In view of the fact that there are plasmas in the Universe with considerable electron thermal energy contents this feature can be relied upon in order to produce generation or conversion of magnetic energy, high energy particle populations and momentum and angular momentum transport. 相似文献