基于阴阳极协同作用的低液滴溅射率真空弧放电技术研究

Cathodic vacuum arc discharge which can provide multicomponent ion beams has been widely used to deposit hard composite coatings. As the energy is supplied to the cathode, droplets are formed under the action of extremely high plasma pressure caused by extremely high power density injected into the cathode, which will affect the quality of composite coatings. The critical issue to reduce the droplets is modulating the energy and power density injected into the electrode. This project concerns the research on the vacuum arc discharge for low sputtering rate of droplet based on cooperating discharge of cathode and anode. Using high melting point cathode and low melting point anode, the rate of mass evaporation and particle ionization of anode is enhanced under the heating effect of incident cathodic plasma. Based on cooperating discharge of cathode and anode, the plasma pressure acting on one electrode will reduce due to the decline of energy and power density, which can provide multicomponent ion beams with low sputtering rate of droplet. The influence of modulating the energy and power density injected into the electrode will be revealed, the mechanism of spot generation and particle ionization will be discussed, the time and space evolution of vacuum arc spot and characteristic parameter of multicomponent ion plasma will be studied, and the characterization of electrode erosion and droplet sputtering will be investigated. The purpose of this project not only means to increase the understanding of vacuum arc discharge, but also provide a novel way to deposit hard composite coatings to meet the application requirement of technology and industry.

利用阴极真空弧放电产生混合成分离子束可用于制备硬质复合涂层，但放电能量全部注入阴极，极高的功率密度形成的极高等离子体压力导致阴极溅射大量液滴，影响复合涂层质量，因此调控注入电极的能量和功率密度是减少液滴溅射的关键。本项目通过开展基于阴阳极协同作用的低液滴溅射率真空弧放电技术研究，提出高熔点阴极匹配低熔点阳极的设计思路，利用阴极等离子体轰击加热阳极效应，加速阳极蒸发电离进而形成等离子体，实现阴阳极协同放电来降低注入单个电极的能量和功率密度，从而降低等离子体压力，最终既减少液滴溅射又产生混合离子束；本项目研究将揭示调控注入电极能量的影响因素，阐明阴阳极协同放电产生弧斑和粒子电离的物理机制，深化对真空弧斑时空演化特性的认识，获得混合离子等离子体的关键特征参数，掌握电极烧蚀和液滴溅射特性，不仅可增进真空弧放电理论认知，还可提供潜在的复合涂层制备方法，以满足现代科技及工业的应用需求。

本项目2019年度立项，研究周期3年，主要研究内容有：通过开展基于阴阳极协同作用的低液滴溅射率真空弧放电技术研究，通过匹配不同材料阴阳电极设计、优化放电结构、电流和背景气氛等途径，掌握调控注入电极能量的影响因素，阐明阴阳极同时产生弧斑和粒子电离的物理机制， 深化对阴阳极真空弧斑时空演化特性的认识，获得混合离子成分等离子体关键特征参数及其变化规律。.本项目主要提出了一种利用阴阳极协同放电产生混合离子束方法，并通过建立阴极场发射、蒸发电离形成初始等离子体、轰击阳极并蒸发，极间粒子碰撞电离的放电物理模型，揭示了阴阳极协同放电弧斑演化的竞争机制，获得了材料、极间距等参数对协同放电的影响规律。深化了对阴阳极真空弧斑时空演化特性的认识，讨论了影响阳极斑出现的因素，表明注入阳极表面的功率密度和阳极材料性质的匹配关系是阳极斑形成的关键因素。同时获得混合离子成分等离子体关键特征参数及其变化规律，背景气体会通过与等离子体相互作用，发生电荷交换反应，影响等离子体成分，基于静电探针获得了短间隙真空弧放电离子电流大小及其空间分布规律，表明阳极参与放电以后会影响到等离子体的扩散形态。以上结果加深了对阴阳极协同放电的理解，获得的通过阴阳极协同放电产生混合离子束的条件及影响因素对于其应用有重要的参考价值。