基于高密度等离子体的束流研究

发布时间：2018-09-12 13:11

【摘要】：高密度等离子体/离子束流在等离子体材料制备和表面处理等方面有着广泛的应用。放电模式和放电条件决定了束流的特性,而束流的特性是其实现工业应用的关键。研究等离子体束流的动力学特征,对于理解等离子体上艺的机制以及优化工艺参数都有着重要意义。本论文开展了基于ECR和ICP两种放电的等离子体束/离子束的特性研究,进行了束流在材料制造方面的初步应用探索。针对ECR放电,采用多种气体放电形成等离子体束和离子束,着重研究了这些束流的离子特性,并开展了ECR等离子体/离子束与材料相互作用的研究工作。首先,利用等离子体质量能量分析仪EQP对ECR氮氩混合等离子体的离子成分和能量分布函数进行了诊断。当改变气体配比、放电功率和气压时,两种主要离子Ar+和N2+的离子能量分布会产生复杂变化：离子的峰形在单峰、双峰、三峰之间相互转变,且对于Ar+和N2+不尽相同,同时离子峰的位置将产生偏移。这种复杂变化主要由ECR特殊结构引起的分布式电离以及粒子间电荷交换作用导致,同时与单双原子的分子结构有关。比较了ECR氢等离子体束和离子束中的离子成分和能量分布情况。两种束流中均含有H+、H2+和H3+三种离子,但是相对含量不同：在氢等离子体中H2+最多而在氢离子束中H3+为主要成分。功率的增加和引出偏压的提高会分别使等离子体束和离子束中离子特性发生改变：各离子相对浓度均会发生变化,同时离子能量分布展宽变宽,并且高能部分离子数都相对增加,这和离子间的相互转化以及空间电场的加速过程有关。利用ECR氩离子束对钨材料进行了辐照实验,并研究了引出偏压、辐照时间、基底温度、离子束入射角度等参数对于辐照结果的影响。经过辐照后,在扫描电镜下可观察到钨表面出现了不同程度的凹凸,表明该离子束与钨材料相互作用方式基本为物理溅射：离子轰击能量、轰击时间的增加会加剧凹凸程度；基底温度则基本不影响辐照效果：在离子束垂直入射材料表面时溅射作用最为明显。利用ECR氮氩等离子体束进行了制备氮化铁磁性薄膜材料的可行性实验。实验中发现,纯氮气条件下和溅射靶偏压较低时都未能成功制备氮化铁薄膜。这是因为原子因溅射作用脱离靶材进入气相环境的过程与离子的轰击能量相关,离子能量不足时,较低的溅射产额不足以在基底上形成膜材料。而加入一定比例氩气进行混合放电以及提高靶偏压均能加强离子的轰击效应,从而提高了单位时间的溅射产额,成功制备出薄膜材料。XRD和磁光克尔效应表明,所获得的薄膜材料为多种相结构的铁氮化合物,具有良好的铁磁性。针对ICP放电,设计了一套大气压甚高频ICP微等离子体射流产生装置,研究了这种射流的放电特性,并初步开展了射流与材料相互作用的应用研究。利用该装置,在功率为90W的条件下得到了长度近3cm宽近3mm的温热等离子体射流。气流量的增加会使射流呈现层流到湍流的转变,长度先增后减：而功率对于射流长度的影响存在着一个上限,当馈入等离子体的能量与等离子体扩散损失的能量达到平衡时射流最长。通过二次点火分别得到了接近于室温和温度达几百度的两种不同的等离子体状态。这种状态变化同时伴随着等离子体形态、射流长度、线圈电流以及电源功率的变化,表明等离子体发生了E-H的放电模式转变,这是由于二次点火导致了等离子体瞬间阻抗的变化。阻抗的变化导致了等离子体密度的骤变,并进一步引起了功率吸收效率的改变。进行了ICP微等离子体射流在微尺寸铜金属快速成形技术中的初步应用研究,得到了球冠状和柱状铜金属件。在SEM下观察到沉积物表面颗粒尺寸远小于铜粉颗粒,表明铜粉被充分熔融。XRD结果显示沉积物表面存在较弱的Cu2+1O峰,这是由于沉积过程中周围空气的卷入导致沉积物出现微弱氧化。
[Abstract]:High density plasma/ion beam is widely used in plasma material preparation and surface treatment. The discharge mode and conditions determine the characteristics of the beam, and the characteristics of the beam are the key to its industrial application. In this paper, the characteristics of plasma beam/ion beam based on ECR and ICP discharges are studied, and the preliminary application of beam in material manufacturing is explored. First of all, the ionic composition and energy distribution function of ECR nitrogen-argon hybrid plasma are diagnosed by using plasma mass and energy analyzer EQP. When the gas ratio, discharge power and pressure are changed, the ionic energy of the two main ions Ar + and N2 + is determined. Complex variations in the distribution of quantities occur: the shape of the peaks of ions changes from one peak to two, and from one to three, and the positions of the peaks are different for Ar + and N2 +, while the positions of the peaks are offset. The ion composition and energy distribution in the ECR hydrogen plasma beam and ion beam are compared. Both beams contain H +, H2 + and H3 + ions, but the relative contents are different: H2 + is the most in the hydrogen plasma and H3 + is the main component in the hydrogen ion beam. The increase of power and the increase of the extraction bias will cause the plasma deviation, respectively. Ion properties in daughter and ion beams change: the relative concentration of ions changes, and the energy distribution of ions broadens, and the number of high energy ions increases. This is related to the mutual transformation between ions and the acceleration of space electric field. The effects of extraction bias, irradiation time, substrate temperature and incident angle of ion beam on the irradiation results were studied. After irradiation, the concave and convex surface of tungsten was observed under scanning electron microscope. The results show that the interaction mode between ion beam and tungsten material is basically physical sputtering: ion bombardment energy, bombardment time. The increase of substrate temperature has little effect on the irradiation effect: the sputtering effect is most obvious when the ion beam is perpendicular to the surface of the material. FeN thin films can be successfully prepared. This is because the atom escape from the target and enter the gas environment due to sputtering is related to the ion bombardment energy. When the ion energy is insufficient, the lower sputtering yield is insufficient to form the film material on the substrate. XRD and magneto-optic Kerr effect show that the obtained thin films are ferro-nitrogen compounds with various phase structures and have good ferromagnetism. A set of very high frequency ICP microplasma jet generator at atmospheric pressure is designed for ICP discharge. The discharge characteristics of the jet and the application of the interaction between the jet and the material were studied preliminarily. Using this device, a warm plasma jet with a length of nearly 3 cm and a width of nearly 3 mm was obtained under the condition of 90 W. The increase of the flow rate will make the jet change from laminar flow to turbulent flow. The length of the jet increases first and then decreases. There is an upper limit on the effect of the plasma on the plasma. The jet is the longest when the energy fed into the plasma is in equilibrium with the energy lost by the plasma diffusion. The change of coil current and power supply indicates that the E-H discharge mode of the plasma changes, which is caused by the change of instantaneous plasma impedance caused by the secondary ignition. The change of impedance leads to the sudden change of plasma density and further changes of power absorption efficiency. Spherical coronal and columnar copper parts were obtained by preliminary application of rapid prototyping technology for cu-in-cu metals. Particle sizes on the surface of deposits were observed to be much smaller than those of copper powders under SEM, indicating that copper powders were fully melted. XRD results showed that there was a weak Cu2+1O peak on the surface of deposits, which was caused by the entrainment of ambient air during deposition. Weak oxidation occurs in sediments.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O53

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