动态真空校准装置的设计

Design of Dynamic Vacuum Calibration Apparatus

动态真空校准装置由供气系统、抽气系统、校准系统、烘烤系统、测控及分析系统五部分组成。利用快开超高真空插板阀与限流元件组合的方法,在20ms至1s的时间范围内实现标准压力105Pa至100Pa范围的瞬态阶跃变化。采用稀薄流下DSMC法与连续流下Navier-Stokes方程相结合的模型,确定快速膨胀过程中标准压力时间常数。动态真空校准装置预计达到的技术指标为校准范围10-1Pa～105Pa,合成标准不确定度小于15%。

A novel apparatus has been designed to calibrate vacuum gauge for its response characteristic,which consists of gas supply system,pumping system,baking system,calibration system and control system. In order to establish transient step about dynamic vacuum in the pressure range from 105 Pa to 102 Pa during 20 ms to 1 s,a very fast-opening ultra-high vacuum gate valve and flow limiting element are combined. By virtue of a hybrid model of continuum part( NavierStokes equation) and the rarefied part( DSMC),the flow states of rarefied gas along the flow limiting element and very fastopening ultra-high vacuum gate valve could be acquired by finite element software,corresponding to the time constant of standard pressure. The standard pressure ranges from 10-1 Pa to 105 Pa with a combined standard uncertainty less than 15%.