双电容结构对电容薄膜真空计输出特性的影响

Effect of Dual-Capacity Structure on Output Characteristics of Capacitance Diaphragm Gauge

单电容结构电容薄膜真空计输出结果常受到工作环境的不利影响,计划设置双电容结构改善这一情况。为研究双电容结构对电容薄膜真空计电容输出特性的影响,根据电容计算理论和FEA(Finite Element Analysis),基于COMSOL Multiphysics软件构建双电容结构有限元模型。通过理论计算和模拟仿真分别得到在不同载荷条件下测量电容和参考电容的理论值和模拟值,分析不同结构的电容随载荷变化情况。结果表明:双电容结构对电容薄膜真空计电容输出特性有一定优化作用。对比单电容结构,双电容结构电容薄膜真空计的优势为,在感压薄膜挠度变化小于其厚度时,线性度提高0.6%,灵敏度降低0.6 pF/Pa;在感压薄膜变形接近固定极板时,线性度提高3.6%,灵敏度降低0.001 pF/Pa。

The output result of capacitance diaphragm gauge with singular-capacity structure is often adversely affected by the working environment. A dual-capacity structure is designed to improve this situation. In order to study the influence of dual-capacity structure on the capacitance output characteristics of capacitance diaphragm gauge, a finite element model of the dual-capacity structure is constructed based on COMSOL Multiphysics software according to capacitance calculation theory and FEA(Finite Element Analysis). Through theoretical calculation and software simulation, the theoretical and simulated values of measured capacitance and reference capacitance under different load conditions are obtained, and the variation of capacitance of different structures with load is analyzed. The results show that the dual-capacity structure can optimize the capacitance output characteristics of capacitance diaphragm gauge. Compared with the singular-capacity structure, the features of the dual-capacity structure of capacitance diaphragm gauge are as follows: when the deflection of the pressure-sensitive diaphragm is less than its thickness, the linearity increases by 0.6% and the sensitivity reduces by 0.6 pF/Pa;When the deformation of the pressure-sensitive diaphragm is close to the fixed plate, the linearity increases by 3.6% and the sensitivity reduces by 0.001 pF/Pa.