光学零件等离子体射流加工去除函数多参数建模及其调控机制研究

The optical surface figuring accuracy and convergence efficiency are decreased due to the incorrect input and low stability of removal function of the plasma jet processing. In this project, research on multi-parameters modeling and control mechanism of removal function of the plasma jet processing will be proposed to solve the problem. Based on the interdisciplinary theoretical research, and starting with analyzing the excitation and physical-chemical properties of the plasma at atomic level, a plasma jet processing model will be proposed which is formed under the comprehensive effects of multi-physical fields and chemical reactions. The surface distribution and evolution mechanism of the jet properties in microscale and macroscale, such as jet velocity, temperature, densities and fluxs of reactive species will be then revealed based on the model. The internal relations between plasma jet properties and feature characteristics of the removal function will be investigated. To assist in establishing an accurate multi-parameters mathematical model, the key characteristic parameters of the plasma jet which influence feature characteristics of the removal function will be extracted and parameters for physical-chemical reactions will be reasonably selected and calibrated. The dependency and sensitivity of the removal function on processing parameters will be studied based on the theoretical model and processing experiments. Error sources which influence the control accuracy of the removal function will be analyzed. Control method and compensation strategies in improving the long-term stability of removal function will be obtained. The high precision control mechanism of removal function will finally be grasped. The results of this projet will provide technical support for manufacturing optics with high precision and high efficiency which are urgently needed by the national key basic research projects and strategic technologies.

针对等离子体射流加工去除函数输入不准确和长时稳定性差导致的光学零件修形精度和收敛率低的问题，本项目提出等离子体射流加工去除函数多参数建模和调控机制研究。以多学科交叉的理论研究为基础，从原子层级的等离子体激发和物理化学反应分析入手，建立多物理场和化学反应综合作用下的等离子体射流加工模型，明确工件表面的等离子体射流速度、温度和活性粒子密度和通量等宏微物理化学特性的分布和演变规律；通过研究工件表面射流特性分布与去除函数结构特征的内在联系，提取影响去除函数特征的关键射流特性参数，合理选取和校准物理化学反应参数，建立准确的去除函数多参数模型；结合理论模型和工艺实验，研究去除函数对工艺参数的依赖度和敏感度，分析影响调控精度的误差来源，探索改善去除函数长时稳定性的控制方法和补偿策略，掌握去除函数的高精度调控机制。研究成果可为实现国家重大基础研究和战略技术急需光学零件的高效、高精度攻关研制提供技术支持。

随着超精密光学元件的广泛应用，传统光学加工技术已无法满足其低成本、高效率、无损伤等要求。大气等离子体光学加工作为化学式非接触加工方法，可有效避免加工表面出现机械损伤和裂纹，是一种极具发展前景的新型光学加工技术。但等离子体射流加工还存在去函数输入不准确和长时稳定性差导致的光学零件修形精度和收敛率低的问题，本项目针对这一问题，开展了等离子体射流加工去除函数多参数建模和调控机制研究。通过建立等离子体射流加工的数值仿真模型，揭示了发生器结构对压力场、温度场及流场的影响规律，优化设计了新型的分体式发生器以提升炬管的工作稳定性。建立了等离子体射流特性诊断系统，明确了等离子体射流温度和激发特性的量化诊断指标，定义出边缘温度区域和有效激发区域，并实现真实工况下射流特性的量化诊断。研究了工艺参数对射流特性作用机制，射频功率会显著影响射流的温度和激发程度，从而改变有效激发区域中的各项指标；刻蚀气体流量的提高有助于提高射流的激发程度；等离子体工作气和冷却气的流量过低或过高都会降低射流刚度。基于等离子体射流调控机制的工艺参数优选策略，可实现去除函数特征参数半高宽度和最大去除深度的波动分别在0.17mm和6.1nm内，基本掌握了去除函数的高精度调控机制。依照设定调控策略可快速优选工艺参数，其产生的等离子体射流具有较高加工稳定性。在此基础上，通过分析射流加工特性与去除函数关系，验证了基于射流特性诊断结果预测去除函数的可行性，建立了基于射流加工参数的去除函数多参数模型，该去除函数模型的预测结果与实验结果吻合度较高，其半高宽度和峰值去除率的最大偏差分别为5.82%和10.22%，实现了本项目的研究目标。研究成果可为实现国家重大基础研究和战略技术急需光学零件的高效、高精度攻关研制提供技术支持。