低真空管路中颗粒传输特性研究

Particle Transport Characteristics in Low Vacuum Pipeline

半导体光刻技术、电真空器件等领域对真空环境的要求已不仅局限于真空度,对洁净度也有了更高的要求。研究表明真空系统中某些运动部件在一定条件下会产生细小的颗粒,污染真空环境。因此需要对固体颗粒污染在真空管道中的传输规律和落点分布进行研究,从而为真空环境颗粒污染防护提供理论依据。文章通过模拟软件COMSOL,对固体颗粒在不同气体流态下的传输特性进行了研究。在仿真中颗粒的受力主要考虑自身重力、气流曳力、气流升力的作用。研究了不同压力、抽速、颗粒直径条件下气流对颗粒传输特性的影响。结果表明:在不同环境条件下,气流对颗粒的曳力作用对颗粒运动特性的影响占主导地位。管道抽气过程中,当压力与颗粒直径恒定时,抽速越大,颗粒越容易落在管道出口处甚至直接随气流穿过出口;当压力和抽速恒定时,颗粒直径越小,越容易随气流到达出口;当颗粒直径和抽速恒定时,随着压力的变化,颗粒传输轨迹也相应的变化。

The requirements of vacuum systems,such as semiconductor lithography and electric vacuum devices,are not only limited to vacuum degree,but also put forward higher requirements for cleanliness.The research shows that some components of the vacuum system will produce particle contaminations,which can pollute the vacuum environment under certain conditions.Therefore,it is necessary to study the transport law and distribution of the particulate matter in a vacuum pipeline and provide the theoretical basis for the particle contamination protection method.In this paper,the transport law of particle contamination under different gas flow patterns was simulated via the COMSOL software.In the simulation,the forces applied to the particle contaminations mainly include gravity,drag force and lift force.The effects of pressure,pumping speed and particle diameter on the gas flow and particle transport characteristics were studied.The results show that the drag force of gas flow on particles is dominant in the transport characteristics of particles under different conditions.When the pressure and particle diameter are constant,the increase in pumping speed enhances the probability of particle deposition at the pipeline outlet or even direct particle transport to the outlet through the gas flow.When the pressure and pumping rate are constant,the smaller the particle diameter is,the easier it is to reach the outlet with the gas flow.When the particle diameter and pumping speed are constant,the particle transport trajectory changes correspondingly with the variation of pressure.