# Two-Parameter Probabilistic Model and Experimental Research on Micron Particle Deposition
## 1 Introduction  
The research on the deposition law of micron particles in gas transmission pipelines has been the focus of attention in ultra-clean ventilation technology in the modern laser fusion, precision electronics, aerospace, and biomedical fields. The space cleanliness control of ventilation technology based on the deposition law of micron particles, such as microorganisms and impurities, has become a key factor affecting the development of science and technology in these fields. In the field of laser fusion, the contamination damage of optical elements caused by the deposition of micron-level nonvolatile inorganic particle pollutants is the main factor affecting the service life of high-power laser optical systems driven by large-scale inertial confinement fusion, such as the National Ignition Facility (NIF) of the United States and the Laser Megajoule (LMJ) of France, and the Shenguang series laser devices of China have been exposed to mirror contamination problems during construction and use [1; 2; 3; 4; 5]. The air knife purging method is adopted, which is the mainstream ventilation technology method for clean control in the field of laser fusion at home in China and abroad at present. ventilation transmits high-purity inert gas to purge the mirror surface with an air knife and remove particles on the mirror surface. After blowing by the air knife, the particles can easily rebound against the wall and cause repeated deposition pollution, with the secondary pollution of mirror deposition at different places after moving along the ventilation airflow, thus seriously affecting the stable operation and service life of a high-power laser optical system [6; 7]. In the field of electronic manufacturing, micron-scaleparticle deposition pollution can greatly affect the product yield of integrated circuits [8; 9; 10]. In the manufacturing process, if micro-scale particle deposition occurs on the silicon substrate, or if micro-scale particle deposition occurs on the mask plate, it will cause a short circuit, open circuit, scratch, or pattern transfer defect in the chip circuit, which will affect the performance and reliability of the integrated circuit, and even lead to scrapping it [11]. In the aerospace field, micron particle deposition pollution may exist in the whole process of spacecraft ground production, storage and transportation, low-temperature vacuum operation, etc. Pollution will affect the performance of aerospace products and their payloads, and shorten the life of spacecraft and their payloads, which is undoubtedly a key problem to be controlled for aerospace vehicles with a high reliability and high investment capital and technology density [12]. Among them, ultra-clean ventilation technologies such as vacuum cleaning and blowing removal are widely used in the manufacture and assembly of aerospace products, the removal of particulate pollutants in the final assembly, test, storage, transportation, and launch stages of spacecraft [13; 14], and to ensure the removal efficiency of pollutants and pay attention to the problem of system cross-contamination. In the field of medical engineering, surgical infection is a problem that society, hospitals, and patients pay close attention to. For surgical operations, the incision infection rate is as high as 25.7%, and one quarter of these surgical infections are caused by bacteria floating in the air as micron-sized particles and falling into open wounds [15]. Ultra-clean ventilation technology is recognized as the best way to prevent air infection during surgery. By controlling the flow mode of clean airflow, the effective removal of contaminated particles in the air in the operating room can be realized, and the pollution transmission route of exogenous microorganisms deposited on the surgical wound with particles as carriers can be cut off, to ensure the cleanliness of the wound.