冷等离子改性KDP晶体液膜接触潮解抛光基础研究

High-quality and high-efficient processing of KDP crystal is urgently required for inertial confinement fusion and other major projects. Aiming at the droplet residence in the current deliquescence polishing process that causes the uneven deliquescence and thereby results in the problem of low surface quality, a new method to realize uniform deliquescent polishing of liquid film by cold plasma modification is proposed. Cold plasma will be used for real-time hydrophilic modification. A uniform liquid membrane between polishing pad and plasma-modified KDP surface with micro-mist can be formed to overcome the problem of non-uniform point-like droplet residence in the traditional deliquescent polishing. By controlling the hydrophilicity of KDP crystal and the water content of micro-mist, the contact area and thickness of the liquid membrane were controlled to realize the prediction of the deliquescent area and the deliquescent rate. Some key issues will be studied, including generation, characteristics and effective delivery technology of atmospheric cold plasma and micro-mist that are appropriate for deliquescent polishing. The rule of real-time hydrophilic modification by cold plasma at the polishing interface will be revealed. The deliquescence mechanism of KDP crystal and the movement law of deliquescence region will also be studied. The deliquescence mechanism of two-phase flow (cold plasma and micro-mist) will be explored to establish the prediction model among each processing parameter, processing efficiency and surface quality, and to analyze the influence of different processing parameters on the sub-surface damage of KDP crystal. New technical foundation for deliquescent polishing contacting with water film is expected to be built to realize high-efficient and low-damage processing of KDP crystal.

KDP晶体高质高效加工是惯性约束核聚变装置等重大工程的迫切需求。针对现有潮解抛光工艺存在的液滴驻留引起非均匀潮解，进而导致表面质量偏低的难题，提出通过冷等离子体改性实现液膜接触均匀潮解抛光的新方法。利用冷等离子体实时亲水改性，借助微汽雾在改性表面形成均匀面域液膜接触潮解，克服传统潮解抛光非均匀点状液滴驻留的不足。通过控制KDP晶体的亲水性、微汽雾的含水量调控液膜接触面积和厚度，进而实现潮解区域和潮解速率的预测。研究适于潮解抛光的冷等离子体和微汽雾的获取、特性检测、有效送达的方法及关键技术。揭示冷等离子体在抛光界面的实时亲水改性规律、KDP晶体微汽雾潮解的机理和潮解区域移动规律。探明冷等离子体-微汽雾两相流潮解去除作用机理，建立各工艺参数与加工效率和表面质量之间的预测模型，分析不同工艺参数对亚表面损伤的影响规律。形成新的液膜接触潮解抛光技术基础，为实现KDP晶体的高效低损伤加工提供新方法。

本项目针对现有潮解抛光工艺存在的液滴驻留引起表面非均匀潮解，进而导致表面质量难提高的问题，提出通过冷等离子体改性实现液膜接触均匀潮解抛光的新方法。依托该项目，共发表相关学术论文15篇（SCI/EI收录14篇），授权发明专利1项，获湖南省科技进步一等奖1项，支撑7名研究生进行相关研究工作。主要的研究进展包括：（1）获得了大气压冷等离子体和微汽雾产生、特征诊断及有效送达的方法，设计并搭建了冷等离子体改性KDP晶体液膜接触潮解抛光系统。（2）揭示了大气压冷等离子体对KDP晶体表面亲水性改性的调控机理和规律，利用冷等离子体实时超亲水改性实现了材料去除层与改性层的对应，微汽雾在超亲水改性的表面形成均匀液膜实现了材料可控均匀潮解。（3）揭示了冷等离子体改性液膜接触潮解抛光工艺及超光滑表面形成机理。液体在KDP晶体表面由液滴驻留向液膜接触转化，促使KDP表面均匀潮解去除，通过“潮解→去除→再潮解→再去除”的模式获得了超光滑表面。（4）研究了冷等离子改性对KDP元件性能的影响。冷等离子体亲水改性KDP表面后，润湿性会逐步恢复至原状，且未对表面形貌造成损伤，因此不会影响使役性能。本项目的顺利实施形成了新的液膜接触潮解抛光技术基础，为实现KDP晶体的高效低损伤加工提供了新工艺。