空间探测小型质谱仪关键技术研究

Research on the Key Technology of Miniature Mass Spectrometer in Space Exploration

小型质谱仪的理论和应用研究对于空间探测具有非常重要的意义,针对商用质谱仪存在的缺点,采用静电双平方离子势阱和离子聚焦技术设计了空间有机分子小型质谱探测器。探测器由质谱传感器、分压控制电路及微电流检测放大电路构成。圆柱形传感器腔体内置多个不同电位的环形电极,在腔体轴向上形成双平方离子势阱,离子在势阱中可形成稳定振荡,振动频率与离子质量成一定的反比关系。通过测量法拉第杯产生的电信号,经FFT提取振动频率,从而探测有机分子质量。在理论上,其主要技术指标为：质量扫描范围m/z1~2 000,分辨率〉400,灵敏度〉100cps/ppb,总质量〈4.5kg,功耗〈5 W,码速率〉1.5kbps。初步调试结果验证了该技术具有一定的可行性,后期可通过对离子源及其与质谱传感器配合的研究来完成整机的具体性能指标测试。

Research on the theory and application of miniature mass spectrometer is very important in the field of space exploration. The commercial mass spectrometers have the disadvantages of large weight, large size, high energy consumption and complex realiza- tion principle, which are difficult to be applied in the field o.f space exploration. The small mass spectrometry detector of organic molecules in space was designed by using electrostatic double square ion trap and ion focusing technique. The detector consists of mass sensor, voltage control circuit and micro current detection amplifying circuit. The sensor has a cylindrical shape, and multiple ring electrodes with different potential are built in its cavity. Double square ion trap is formed in the axial direction of the cavity, and the ion can form stable oscillation in the potential well. Ion of different charge-mass ratio has different vibration frequency, and its vibration frequency is inversely propor- tional to the ion mass. Under the action of the extraction electrode, the signal generated by measuring the Faraday tube and vibration frequency is extracted by FFT. Thus the mass of organic molecules can be detected. In theory, the main technical indexes are as follows ： mass range of m/z 1-2 000, resolution〉400, sensitivity〉100 cps/ppb, mass〈 4.5 kg, power〈5 W, code rate〉1. 5 kbps. The feasibility of the technique is verified by the preliminary test results. In the later stage, the specific performance of the whole mass spectrometer will be tested by the study of the ion source and its combined with mass sensor.