【作者】 张宇；

【导师】 王晓钢； 刘金远；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2005， 硕士

【摘要】 尘埃等离子体是一种包含带电尘埃颗粒的电离气体,一般由电子、离子和带电尘埃颗粒组成,它广泛存在于星际空间、电离层以及等离子体辅助加工设备中.本文针对实验室中尘埃等离子体的研究集中的两个方面:在等离子体材料加工工业中尘埃污染的清除以及尘埃等离子体在基本物理理论中的应用,分别通过数值模拟的方法对尘埃等离子体作了理论研究。本文首先提出了除尘的方法。针对柱状等离子体发生器系统,在理论上提出了一种利用E×B力清除尘埃的方法,并采用三流体模型,模拟了电子、离子及尘埃在电磁场的作用下的运动模式,数值模拟的印证了所提出的除尘方法。接下来,研究了一维及两维鞘层的性质。在实验室中尘埃晶格实验中尘埃粒子一般被束缚在柱槽状电极鞘层中,鞘层的性质影响并决定尘埃的运动。针对一维鞘层,用流体的方法模型并研究了其性质,并且把模型推广到二维情形,即柱槽状电极情况,得到了束缚尘埃的鞘层的性质,为后来的研究作了铺垫。在此基础上,对尘埃粒子建立了分子动力学模型研究了尘埃晶格。由于得到了束缚电极鞘层的情况,考虑了尘埃粒子数相对较少的时候,尘埃粒子对电极鞘层影响较小,故假设尘埃粒子不影响鞘层性质。通过考虑每个尘埃粒子的重力、充电过程、所受离子拖拽力及尾流作用,建立了描述尘埃运动的分子动力学方程,模拟了尘埃晶格,并对影响尘埃晶格的性质作了一定的讨论。最后对尘埃空洞实验[R.P.Dahiya et al.,Phys.Rev.Lett.89,125001(2002) ]作了模拟,并且讨论了实验室中尘埃空洞的形成原因,得到结论为由于圆柱形柱槽状电极在底部中心部分会形成一个微弱的势阱,此势阱排斥尘埃粒子形成空洞。更多还原

【Abstract】 Dust plasma is the ionized gas containing colloid nano/microscopic particles (dust). Generally, the dust plasma, composing of electrons, ions and charged dust particles exist in both the space and the laboratory. In the present paper, two main aspects: the dust elimination in plasma application and dust crystals in basic colloid physics have been discussed with simulation method.Firstly, a new method to eliminate dust particles wa"s designed. For a cylindrical plasma discharge chamber, a devise to eliminate the dust with the aid of the E×B drag force was schemed out and validated with a three fluid model.Then, the one dimensional and two dimensional sheath characteristics have been studied. In the dust crystal experiments, the dust particles are normally confined in a two dimensional sheath of a concave electrode. The sheath characteristics affect and determine the dust particles’ characteristics and there motions, which makes it necessary to obtain the sheath characteristics to study the dust particles. So a two fluid model has been preformed" to study the one dimensional and two dimensional sheaths, which provides the basal information for the later works.A molecular dynamics equation of dust particles has been presented to study the dust crystals. Considering that there are few dust particles so that the dust particles do not influence the sheath formation, a bold dust molecular dynamics model has been established, in which the gravities of dust particles, dust charging, ion drag force and wake wield have been included. Through the model, different crystalline structures of dust particles have been simulated and discussed.At last, formation of dust void has been simulated and discussed. A numerical dust void experiment has been preformed comparing to the experiment of [R. P. Dahiya et al., Phys. Rev. Lett. 89, 125001 (2002)]. The results of the two experiments agree extremely well. Then from the simulation, It is found that the formation of the dust void in the axisymmetric three dimensional sheath is due to a gentle potential bump in the central region of the electrode caused by the cylindrical geometry.更多还原