【作者】 吴迪；

【导师】 宫野；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2006， 博士

【摘要】 强流脉冲离子束因其自身的诸多优越性，在材料领域里越来越受到重视。不同能量密度的束流因与靶作用效果不同而用来进行不同的研究目的，较低的可以直接用于改性，较高时既可以用来改性又可以用来沉积薄膜及制备纳米粉。如何针对不同的靶材控制工艺参数达到实现不同的目的，需要从理论上进行指导，不能仅凭经验确定，因而建立有效的数值方法来解决这一非线性问题是非常必要的。 紧密结合我们三束材料改性国家重点实验室从俄罗斯引进的TEMP型强流脉冲离子束（IPIB）加速器，根据拟合实测磁绝缘二极管（MID）电压波形以及采用法拉第筒检测的离子流密度建立了相应的物理模型，研究了IPIB辐照靶材过程中二次电子发射问题，提出了混合离子束发射二次电子模型，对IPIB辐照期间产生的二次电子的演化及其形成的电场的演化等问题进行了研究。发现对喷发等离子体起定向及加速作用； 研究了辐照过程中热力学效应，建立了烧蚀过程的一维、二维模型，对Ti靶的烧蚀过程进行了数值计算，给出了烧蚀斑痕的时空演化过程。烧蚀过程中，靶物质被层层剥离，剥离速度为10m／s量级，远远小于等离子体的喷发速度。并且烧蚀过程中斑痕由碗状变化到井状，影响等离子体的喷发方向。同时发现在所研究的能量密度范围内，接近脉冲结束时，烧蚀深度和宽度不再增加，即等离子体喷发是在脉冲时间内完成的。还得到了脉冲处理过程中靶材内部的温度场分布及其演化规律，计算了脉冲期间的升温速率（-10⁹K／s）。模拟研究了MID阳极采用聚乙烯涂层和采用石墨时由于束流中不同种类离子份额不同而产生的不同效应。碳离子入射靶材射程较短，而质子相对较长，因而MID采用石墨阳极时束流能量主要沉积在表层，而采用聚乙烯涂层时能量沉积相对较深。 研究了辐照过程中Al靶内激波的传播情况，建立了一维激波传播模型。计算了能量密度为5J／cm²和10J／cm²时，Al靶内的压力的空间演化。脉冲刚刚结束时压力衰减较快，随后在靶内衰减变慢。但产生的等离子体向真空中喷发时压力衰减较快，等离子体几乎同时到达空间某处。 根据能量和动量守恒原理，建立了等离子体向不同压强背景气体中喷发的二维气体动力学模型，计算了背景气体压强为真空、10^-6大气压、10^-4大气压、10^-3大气压、10^-2大气压及大气压时产生的等离子体的喷发情形。当背景气压为10^-6大气压时，可以将其视为真空，10^-4大气压时，背景气体空间存在扰动；随着背景气压升高，等离子体移动受到限制，压力越大，移动速度越小，移动距离越短。特别当背景气压为大气压强的1／1000时，背景气体中产生激波，等离子体羽形成了“雪犁”状，分为近表面的慢速移更多还原

【Abstract】 Because of being have many advantages for intense pulsed ion beam, it has been pay more attention in the field of materials. IPIB has been used for different motivation for the different effects of the interaction between target and beams with different energy densities. For lower energy density of IPIB, It can be directly used to modify materials; for higher one, it can be used to modify the target and also can be used to deposit film, and to produce nano-size powder. How to control the working references to realize the results for the different target? It needs the guidance theoretically. It is not enough to decide what the parameters of the IPIB should be used by experience. Therefore it is necessary to establish the executing method numerically to deal with the nonlinear problem.From the beginning of create the models according to the fitting results of the waves of magnetically insulated ion diode of the TEMP type accelerator imported from Russia and the ion current density detected by Faraday cup at the focus region, many problems have been discussed, such as the effects of SE emission problems during the irradiation period of target by IPIB, and established a model dealing with mixing ions in the beams; and obtained the evolution profiles of SE and electric field during the beam pulse, found that the field take the role of accelerating and orientation the ions in the beam;The thermal and dynamic effects have been discussed during the irradiation period, and established the one-dimensional and two-dimensional models to describe the ablation process; and calculated the ablation process deeply, obtained the temporal and spatial evolution process of ablation of target. During the ablation of target, target material ablated layer by layer, the ablation velocity reached about 10m/s, it is far less than the ejection speed of the plasma formed by IPIB irradiation target. During the ablation process the scar changed from bowl to well, certainly it affects the ejection direction of plasma. It has been found that among the researching energy densities, the ablation depth and width will not increase while the ablation time near the end of a pulse, it means that the ejection of plasma will finish at the end of a pulse. The temporal and spatial evolution of temperature field of target has been obtained during the IPIB irradiation, the temperature rising rate reaches -10~9 K/s during a pulse.Different effects for impacting on target of IPIB consists of different ratio of ions because of using polyethylene coating or graphite anode of MID of the accelerator have been researched; the range of carbon ion is shorter and the range of proton is longer, therefore the更多还原