Modifying Wire-Array Z-Pinch Ablation Structure and Implosion Dynamics Using Coiled Wires
Modifying Wire-Array Z-Pinch Ablation Structure and Implosion Dynamics Using Coiled Wires
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DOI：
10.1109/tps.2009.2014763
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发表时间：
2009-03
影响因子：
1.5
通讯作者：
G. Hall;S. Bland;S. Lebedev;J. Chittenden;J. Palmer;F. Suzuki-Vidal;A. Harvey-Thompson;G. Swadling-G
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文献类型：
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作者：
G. Hall;S. Bland;S. Lebedev;J. Chittenden;J. Palmer;F. Suzuki-Vidal;A. Harvey-Thompson;G. Swadling-G
盘绕阵列是一种圆柱形阵列，其中每根导线形成螺旋形，可以抑制基波长处的烧蚀调制。在线芯附近外，来自线圈阵列的烧蚀流在线圈波长处被调制，并在r， θ平面上具有两流结构。在螺旋线附近，烧蚀集中在方位角位移最大的位置，等离子体从这些位置向轴向传输，使得流与离阵列轴最远的线圈部分对齐。GORGON MHD代码精确地再现了这种观察到的烧蚀结构，可以用J乘以B的力来理解，这些力是由全球磁场与螺旋电流路径以及模拟中提出的附加电流路径相互作用产生的。有了这种控制烧蚀流线发生位置的能力，大波长线圈被构建，使得导线中形成的断裂具有足够的轴向分离，以防止内爆护套中的扰动合并。这产生了一种新的内爆模式，在这种模式下，全局不稳定性可以得到控制，阵列中所有导线之间的扰动相互关联。对于大波长的八线线圈阵列，这产生了x射线功率的显著增加，相当于32线直线阵列。这些实验是在英国伦敦帝国理工学院用于等离子体内爆实验（1 MA, 240 ns）的兆安培发电机上进行的
Coiled arrays, which are cylindrical arrays in which each wire is formed into a helix, suppress the modulation of ablation at the fundamental wavelength. Outside the vicinity of the wire cores, ablation flow from coiled arrays is modulated at the coil wavelength and has a two-stream structure in the r, thetas plane. Within the vicinity of the helical wires, ablation is concentrated at positions with the greatest azimuthal displacement, and plasma is axially transported from these positions such that the streams become aligned with the sections of the coil furthest from the array axis. The GORGON MHD code accurately reproduces this observed ablation structure, which can be understood in terms of J times B forces that result from the interaction of the global magnetic field with a helical current path as well as additional current paths suggested by the simulations. With this ability to control where the ablation streamers occur, large wavelength coils were constructed such that the breaks that form in the wires had sufficient axial separation to prevent perturbations in the implosion sheath from merging. This produced a new mode of implosion in which the global instability can be controlled, and perturbations correlated between all wires in an array. For large-wavelength eight-wire coiled arrays, this produced a dramatic increase in X-ray power, equaling that of a 32-wire straight array. These experiments were carried out on the mega ampere generator for plasma implosion experiments (1 MA, 240 ns) at Imperial College London, London, U.K.