In many cases, we need to seal a certain amount of space to prevent gases or liquids from flowing into or out of this space under pressure, such as vacuum equipment (vacuum coater, liquid crystal implanter, PVD, semiconductor epitaxy, etc.). Working under vacuum conditions requires that air cannot be leaked into the working chamber during work. Otherwise, production can not be carried out, or defective products can be wasted and human and material resources can be wasted. In addition, liquid or gas containers (hydraulic cylinders, oxygen cylinders, air-conditioner refrigerators, etc.) are required to have no gas or liquid leakage in the presence of a pressure difference between inside and outside of the container. If there are leaks, the consequences are serious, which will generally result in the waste of effective materials, such as the leakage of toxic materials and corrosive gases, and even cause accidents.
Before these products or equipment with requirements for tightness are put into use, they must be leak checked first, and in the course of use, they must also be regularly checked for leak detection using a helium-mass spectrometer leak detector.
2, the degree of leakage of quantitative
The degree of leakage of the container is quantified by the leak rate. Definition of leak rate
Where: ΔP is the change in pressure
V is the volume of the container Δt is the amount of time change
3. Principle of Helium Mass Spectrometer Leak Detector
Helium mass spectrometry leak detection technology is an indispensable technology in the field of vacuum leak detection. Due to its high leak detection efficiency, easy operation, sensitive instrumentation, high precision, and low interference with other gases, it has been found in the resistance furnace leak detection. widely used.
The helium mass spectrometer leak detector is an air tightness tester made from helium gas as a leak gas according to the principle of mass spectrometry. It consists of a mass spectrometer room, an air extraction system, and an electrical part that consists of an ion source, an analyzer, a collector, and a cold cathode ionization gauge. The electrons emitted from the filaments in the mass spectrometer oscillate back and forth inside the room and collide with the indoor gas and the helium gas that enters the chamber through the leak hole to ionize into positive ions. These helium ions enter the human magnetic field under the action of an accelerating electric field. Due to the Lorenz force acting to deflect, forming an arc-shaped track
Road, changing the accelerating voltage allows ions of different masses to be detected by the magnetic field and the receiving slot to the receiver. Sneeze and suction methods are the two most commonly used methods for the leak detection of helium mass spectrometer leak detectors.