摘要
惰性元素氦具有特殊的地球化学特性.质量轻、扩散力强.在常温常压下为无色无味的气体.地球上的氦主要来自铀、钍等放射性元素α裹变产物.根据地下放射性成因、分析氦的含量或同位素组成.可用于铀矿、石油、天然气、氦气田,地热资源勘探以及地震予报等.但由于氦的含量非常低,且空气中仅为524ppm,在此微量基础上往往5%～10%的变化就认为是异常,因此要求仪器测氦灵敏度要高,高精度、高准确度.从五十年代末。
A mass spectrometer for determining helium in air, water and soil is introduced. A small quadrupole is used in the instrument. The frequency of its quadrupole electric field is 5MHz. The ion source is of twin-cathode configuration. The sensitivity for determining helium can reach ppb level with a Faraday collector to detect ions and a static vacuum system consisting of a small Zr-Al pump. A special quantitative sampling system and a photoelectric pressure measurement system are designed, making the analysis more speedy and accurate. The main performances for the applications in uranium geology, oil exploraton and earthquake forecast are described.
出处
《分析仪器》
CAS
1991年第3期40-43,共4页
Analytical Instrumentation
