What is helium mass spectrometry leak detection technology
At present, helium mass spectrometry has become the most sensitive and widely used leak detection technology.
Helium mass spectrometer leak detector principle:
Helium mass spectrometer leak detector is a mass spectrometer or mass spectrometer which is made of mass spectrum principle. Through the mass spectrometer's core component, the mass spectrometer turns gases of different mass into ions and moves in a certain field. Ions with different mass to charge ratios are separated from each other in the field, while ions with the same mass to charge ratio are gathered together in the field. If the receiver is placed at an appropriate position to receive all these ions, the mass spectrum map arranged in sequence according to the mass to charge ratio will be obtained Mass spectrometry. The mass spectrometer used for leak detection is called mass spectrometer leak detector. All mass spectrometers for measuring gas partial pressure, such as quadrupole mass spectrometer, radio frequency mass spectrometer, time of flight mass spectrometer, cyclotron mass spectrometer, etc., can be used for leak detection.
The specially designed mass spectrometer with helium as tracer gas is called helium mass spectrometer leak detector. In addition to its high sensitivity, the instrument has the advantages of wide application range, accurate positioning and quantitative, non-toxic, safe and fast reaction speed. The most commonly used helium mass spectrometer is the 90 ° and 180 ° magnetic bias transition mass spectrometer.
As we all know, when a charged particle (positive ion) enters the analyzer of uniform magnetic field at the velocity of V, if the direction of velocity V is perpendicular to the direction of magnetic field H, then its trajectory is circular. When the magnetic flux density of magnetic field is constant, ions with different mass to charge ratio (M / E) have corresponding transport radius in the magnetic field, that is to say, they all have corresponding circular trajectories The charged particles will separate from each other after moving in the magnetic field analyzer.
If a baffle is placed in the path of large motion to block other ions, and a slit is opened on the baffle plate at the corresponding motion radius of helium ion, and ion receiving electrode is placed behind the slit. Only helium ion can be received by the receiving electrode through the slit to form helium ion flow, which is indicated by the measuring instrument after being amplified by the amplifier.
During leak detection, if helium is used to blow the leak hole, the helium will enter the mass spectrometer chamber of the leak detector through the leak hole, so that the measuring instrument of the leak detector can react quickly and sensitively, so as to achieve the purpose of leak detection.