helium mass spectrometer leak detector overall structure
Helium mass spectrometer leak detector is a kind of mass spectrometer analysis instrument. It is mainly used in vacuum leak detection. It has the advantages of good performance and high sensitivity. In general, helium mass spectrometer leak detector is composed of mass spectrometer chamber, vacuum system and electrical system. Sometimes auxiliary vacuum system is needed. Taking the leakage detector of 180 ° magnetic deflection transformation analyzer as an example, its main components are explained in detail as follows.
1、 Mass spectrometer room
Visually speaking, the mass spectrometer room is the heart of helium mass spectrometer leak detection. It is composed of ion source, analyzer and electrical system. The cold cathode magnetron gauge is also placed in it to share its magnetic field. In order to facilitate the amplification of tiny particle flow, a high resistance and electrometer tube for the first stage amplification is also placed in the mass spectrometer chamber. The shell of the mass spectrometer chamber is made of non-magnetic material. The inner part of the chamber is evacuated, while the external permanent magnet is set to form the magnetic field of the magnetic analyzer.
2、 Vacuum system
The vacuum system provides the normal working condition of mass spectrometer. It is necessary to set up a high vacuum system because the tungsten cathode needs a vacuum degree of 0.001-0.01 PA when it works normally, and at the same time, it is necessary to establish a high vacuum system. The energy-saving valve in the system is to meet the regulation of the working pressure of the mass spectrometer chamber. When the valve is fully open, the sensitivity of leak detection is high. Therefore, it is better to open the valve larger if conditions permit. In order to calibrate the sensitivity of leak detection, standard leak holes are set in the system.
3、 Electrical system
The core of the electrical part of the helium mass spectrometer is the power supply and measurement of the mass spectrometer. The other parts include the power supply and control part of the vacuum system, the control panel and the output instrument. It mainly includes small current amplifier and output device, low-frequency generator, high-voltage rectifier, transmitting current stabilizing device and high-voltage rectifier to supply cold cathode magnetron gauge power.
4、 Configuration of auxiliary vacuum system
In helium mass spectrometer leak detection technology, according to the structure, size requirements and specific leak detection conditions, it is necessary to set up an auxiliary vacuum system with the functions of pre pumping the tested piece, ensuring the working vacuum of the leak detector, conducting gas diversion, shortening the reaction time and clearing time, and reducing the adverse effect on sensitivity.