Multi-scale simulation and analysis of gas evacuation processes in a microcavity

Abstract

Based on the flow theory applicable to the whole Knudsen number range, a theoretical model for removing air from the target shot in inertial confinement fusion was established, and the reliability of the model was verified by designed experiments. The physical experiment requires the air concentration in the target shot to be lower than 10×10−6, the process of removing air in the target shot was simulated numerically, and the relationship between the air concentration in the target shot, the pressure in the target shot and time was emphatically analyzed. The time cost of three methods for removing the air in the target shot, namely the single-pipe one-time gas evacuation method, the single-pipe circulation gas evacuation method and the double-pipe flow washing method, were calculated and compared. Numerical calculation results show that: in the single-pipe one-time gas evacuation method, the existence of the micro-channel on the target shot has a non-negligible effect on the time required to remove the air in the target shot, and it takes 1961.77 h to make the air concentration in the target shot reach the standard when the micro-channel on the target shot and the gas-filling pipe is considered. In the single-pipe cycle gas evacuation method, the number of evacuation times and the degree of single gas evacuation will affect the total time required to remove the air in the target shot. When the single gas evacuation degree is at the optimal value, the plan that filling three times and evacuation four times can reduce the total time to reach the standard to about 1 h, while the single gas filling and gas evacuation times under this plan are 6 min and 10 min, respectively. However, it only takes 11 minutes to make the air concentration in the target shot reach the standard by using the double-pipe flow washing method.