Dust charging in dynamic ion wakes
Dust charging in dynamic ion wakes
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DOI：
10.1063/1.5124246
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发表时间：
2020-02-01
影响因子：
2.2
通讯作者：
Hyde, Truell W.
中科院分区：
文献类型：
--
作者：
Matthews, Lorin Swint;Sanford, Dustin L.;Hyde, Truell W.
利用分子动力学方法模拟了离子流在尘埃颗粒表面的流动过程，研究了尘埃颗粒与离子流之间的相互作用。的颗粒的充电和动力学耦合，并从离子尘埃相互作用，允许详细分析的离子韦克菲尔德结构和尾场介导的相互作用的尘埃粒子的位置变化。当下游颗粒在尾流内垂直振荡时，当它接近上游颗粒时，它会放电高达30%，然后当它后退时再充电。在充电过程中存在明显的滞后现象，这取决于颗粒是接近还是远离离子密度较高的区域。离子介导的尘埃-尘埃相互作用力的地图显示，尾流区域的径向范围，它提供了一个有吸引力的恢复力的下游颗粒，增加离子流速降低，虽然恢复效果变得较弱。正如最近的数值结果所示，两个颗粒之间没有净垂直吸引力。相反，下游粒子上减小的离子阻力允许其在上游粒子的韦克菲尔德场中“牵引”。
A molecular dynamics simulation of ion flow past dust grains is used to investigate the interaction between a pair of charged dust particles and streaming ions. The charging and dynamics of the grains are coupled and derived from the ion-dust interactions, allowing for detailed analysis of the ion wakefield structure and wakefield-mediated interaction as the dust particles change position. When a downstream grain oscillates vertically within the wake, it decharges by up to 30% as it approaches the upstream grain and then recharges as it recedes. There is an apparent hysteresis in charging depending on whether the grain is approaching or receding from a region of higher ion density. Maps of the ion-mediated dust-dust interaction force show that the radial extent of the wake region, which provides an attractive restoring force on the downstream particle, increases as the ion flow velocity decreases, though the restoring effect becomes weaker. As also shown in recent numerical results, there is no net attractive vertical force between the two grains. Instead, the reduced ion drag on the downstream particle allows it to "draft" in the wakefield of the upstream particle.