Vacuum ion plating machine often needs to use mass spectrometer to control its coating process, and cyclotron mass spectrometer is a kind of energy balance mass spectrometer. It is based on the cyclotron resonance phenomenon of ions in orthogonal high-frequency electric field and DC magnetic field as its working principle. Its basic principle was proposed by Hipple et al. in 1949. In 1951, Thomas et al. first developed a mass spectrometer. In 1954, Alpert et al. developed a simple cyclotron mass spectrometer that can be used to analyze residual gas under ultra-high vacuum, which greatly promoted the development of ultra-high vacuum technology. In 1960, Klopfer developed a complex cyclotron mass spectrometer that can remove the influence of non-resonance ion space charge. The sensitivity of the mass spectrometer can remain unchanged within 10%, making quantitative analysis possible. However, it has the disadvantages of difficult parameter adjustment, complex structure, and difficult to completely degas the internal electrodes.
Since the analyzer and ion source of the cyclotron mass spectrometer are coexisting in a small space, the electric field will be disturbed by non-resonant ions. Therefore, in order to overcome the electric field distortion caused by non-resonant ions, a complex tube-type cyclotron mass spectrometer was developed based on the simple cyclotron mass spectrometer, and its performance is more stable than that of the simple cyclotron mass spectrometer.
The main parameters of the mass spectrometer are: sensitivity constant, cyclotron resonance frequency, maximum radius that non-resonant ions of mass M+△M can reach, resolution, final energy of resonant ions, trajectory length of resonant ions, flight time of resonant ions, and number of cyclotrons of resonant ions.
Its advantages and disadvantages are:
1. Advantages: fewer parts, thin electrodes, small size, less outgassing and almost no "memory effect", etc., especially suitable for residual gas analysis of ultra-high vacuum small volume.
2. Disadvantages: inconvenient operation, nonlinear mass standard, magnetic field required, complex automatic recording of spectral lines, and inability to use electron multiplier for detection, which limits the minimum detectable pressure.
In 1960, a college in Chengdu, my country first successfully developed a cyclotron mass spectrometer; in 1963, the Institute of Electronics of the Chinese Academy of Sciences conducted a detailed study on the working characteristics of a simple cyclotron mass spectrometer; in 1965, the Lanzhou Institute of Physics of the Chinese Academy of Sciences developed a set of simple cyclotron mass spectrometer equipment with a quantitative accuracy of 20%, laying the foundation for the subsequent research and development of mass spectrometers for ion plating machines.
