采用激光吸收光谱法可实现气体同位素丰度的探测, 由于待测气体吸收线的吸收系数会受待测气体温度的影响, 将直接影响气体同位素检测系统的精准度和稳定度, 文中设计并研制了一种高精度的多通池温度控制系统。硬件方面, 采用高精度PT1000铂电阻温度采集电路与聚酰亚胺电热膜加热装置, 构成了一个完整的闭环温度控制结构。软件方面, 采用Ziegier-Nichols工程整定方法对比例、积分、微分三个系数完成整定。针对被控对象结构复杂响应较慢引起超调量大问题, 采用积分分离比例-积分-微分控制算法, 使温度控制快速且无超调。利用该系统进行温度控制实验, 实验表明: 温度控制范围为18～42 ℃, 温度控制精度达到±0.08 ℃, 稳定时间位15 s,该系统具有精度高、响应快速、无超调的优点, 为激光气体同位素探测提供了可靠保障。

The gas isotope abundance can be detected by laser absorption spectroscopy method. As the absorption coefficient of the absorption line of the gas to be measured can be affected by the temperature of the gas to be measured, the temperature of gas will directly affect the accuracy and stability of the gas isotope detection system. A high-precision multi-pass gas cell temperature control system was designed and developed in this paper. In hardware, a high-accuracy PT1000 platinum resistance temperature acquisition circuit and a polyimide electrothermal film heating device were used to form a complete closed-loop temperature control structure. In software, Ziegier-Nichols′ engineering setting method was used to complete the three coefficient settings of P, I, and D. Aiming at the problem that a large amount of overshoot caused by the complex structure and slow response of the controlled object, the integral separation PID control algorithm was used to make the temperature control fast and without overshoot. The system was used for temperature control experiments, experimental results show that the temperature control range was 18-42 °C, the temperature control precision is ±0.08 °C, and the stabilization time is 15 s. This multi-pass gas cell temperature control system has the advantages of high precision and fast response and no overshoot, which provides reliable guarantee for laser gas isotope detection.