Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585, Japan.
Laboratoire de Physique des Gaz et des Plasmas (LPGP), Université Paris-Saclay, 91405 Orsay, France.
Phys Rev E. 2019 Jan;99(1-1):011201. doi: 10.1103/PhysRevE.99.011201.
Peculiar behavior is found in a Si cluster ion, moving with a speed of ∼0.22c (c: speed of light) in a solid Al plasma in the context of cluster-ion beam driven inertial confinement fusion: The Si ion, moving closely behind the forward-moving Si ion for a distance of several Å in the cluster, feels the wake field generated by the forward Si. The acceleration interaction force on the rear Si ion by the forward-moving ion may balance with the deceleration backward force in the longitudinal-moving direction. The forward-moving Si ion would be decelerated, as an isolated ion is decelerated without correlation. However, the deceleration of the rear Si ion, moving behind closely, would be reduced significantly. The rear Si ion may catch up and overtake the forward-moving Si ion in the cluster during the Si cluster-ion interaction with the high-density Al plasma. This peculiar behavior appears when the ions are aligned well longitudinally. The wake field is confined around the Si ion in the forward and transverse directions for a distance smaller than the Si cluster interionic distance l_{c}. However, the tail of the wake field extends beyond l_{c} due to the Si ion high speed of ∼0.22c. Therefore, the peculiar behavior shown above appears only for the ions in one cluster aligned well longitudinally.
在团簇离子束驱动惯性约束聚变的背景下，在固体 Al 等离子体中，以约 0.22c（c：光速）的速度移动的 Si 团簇离子中发现了一种特殊行为：紧跟在前进的 Si 离子后面的 Si 离子在团簇中以几个 Å 的距离移动，感受到由前 Si 产生的尾流场。后 Si 离子受到前向 Si 离子的加速相互作用力可能与纵向运动方向的减速向后力平衡。前向 Si 离子将减速，就像孤立离子没有关联时减速一样。然而，紧密跟随的后 Si 离子的减速将显著降低。在后 Si 离子追上并在 Si 团簇离子与高密度 Al 等离子体相互作用期间超过前向 Si 离子。当离子在纵向方向上很好地对齐时，会出现这种特殊行为。尾流场在 Si 离子的前向和横向方向上被限制在小于 Si 团簇离子间距离 l_{c} 的距离内。然而，由于 Si 离子的速度约为 0.22c，尾流场的尾部延伸超过了 l_{c}。因此，只有在一个纵向对齐良好的团簇中的离子才会出现上述特殊行为。
