The development and application of æ°¦ mass spectrometer leak detector

The development and application of æ°¦ mass spectrometer leak detector

In the era of continuous development of science and technology, helium mass spectrometry and its application technology are also constantly developing and perfecting. This is mainly determined by two factors: on the one hand, the leak detection application technology constantly puts forward new requirements for the leak detector, and forces the instrument itself to update; on the other hand, the leak detection technology also supplements the existing leak detection at any time and any place. There are some deficiencies in the application process, so the relationship between the two is complementary and mutually reinforcing.
1. Progress of helium mass spectrometer leak detector
After nearly half a century of hard work, today's helium mass spectrometer leak detectors have bid farewell to the situation in the early 1940s.
It is concentrated in the following aspects:
(1) Portable: Recently, the small portable leak detectors introduced by various countries not only have high sensitivity, but also are easy to carry, which provides relatively convenient for field work and aerial work.
(2) Leak detection under high pressure: The pressure of the leak detection port can be as high as several hundred Pa, which is very beneficial for detecting large systems and workpieces with large leaks.
(3) High degree of automation: automatic calibration of peaks, automatic adjustment of zero point, automatic range conversion, automatic data processing, external printer. The whole machine is controlled by the microcomputer, and the menu selection function can complete the full leak detection process with one button.
(4) Dry leak detection with no oil: In some countries, the leak detector can be used as a dry pump to achieve the effect of oil-free vapor, which provides favorable conditions for leak detection of semiconductor devices such as oil-free systems and chips. .
(5) Wide range of leak detection: The four-pole leak detector produced today has a wide range of masses, which can detect not only helium but also other gases.
The molecular pump exhaust system replaces the diffusion pump exhaust system, which not only solves the problem of contamination of the mass spectrometer by oil vapor, but also contributes greatly to the quick start of the instrument and rapid shutdown. In order to adapt to the pressure change of the leak detection port and the sensitivity requirements, the molecular pump generally adopts multi-stage structure and several different speeds.
This can be achieved, for example, by varying the molecular pump speed and improving the leak detection sensitivity.
In addition, the reverse diffusion leak detection method achieves high pressure and strong leak detection, and also provides good conditions for positive pressure sniffer leak detection.
2. Application of æ°¦ mass spectrometer leak detector
The application of helium mass spectrometer leak detectors has gone from academies, universities, laboratories, and a few scientific research institutions to industrial and mining enterprises, and even township enterprises and individual enterprises. It can be said that the application field is extremely broad.
(1) Aerospace high-tech industry
1) For example, the rocket engine and the attitude engine, in the past, the pressure brush soap water leak detection, and now re-improving the process with the æ°¦ mass spectrometer leak detector for leak detection, using a positive pressure sniffer combined with the hood method, so that the leak detection sensitivity is greatly improved, thereby Guaranteed engine quality. The detection of the rocket's arrow body is combined with several methods such as positive pressure sniffer, hood method and accumulation method. Due to the application of the leak detection technology, the sensitivity of the leak detection is improved, and the lack of sensitivity of the instrument during the leak detection by the inhalation method is compensated.
2) KM6 space ring die device is huge, the main vacuum chamber has a diameter of 12m and a height of 22m. In addition, there are auxiliary vacuum chambers and manned cabins. The volume is 3500m3, there are many sub-systems, the structure is complex, and the various interface welds are added several kilometers long. The helium mass spectrometer leak detector is used for negative pressure leak detection. Each weld is sealed by the leak detection box and is equipped with pumping and pumping. After the system draws a low vacuum inside the box, it is filled with a certain pressure of helium, the pre-pumping valve is closed, and the leak detecting valve is opened. Since the concentration of helium in the box is high, the relative leak detector has a certain pressure, so the sensitivity of the leak detection is effectively improved.
3) In the aerospace industry, satellites, various valves, electronic components, sensors, etc. are widely used in mass spectrometer leak detectors and their leak detection technology.
(2) Power industry
SF6 high-voltage switch and zinc oxide surge arrester are important components of power plants and power transmission and transformation in the field. They often cause large-area or partial power outages due to leakage, affecting industrial production and hinder people's normal life. The resulting economic losses are sometimes difficult to estimate.
1) The high-voltage switch is an aluminum casting in the connecting box, which is easy to have blisters, and the leaking hole structure is complicated and difficult to clean. Generally, the leak detection box or the cover method is adopted, that is, the test piece is evacuated, and then the cover is filled with helium gas, and waits for a certain time to determine the total leak rate. Because of the small amount of helium, the detection sensitivity is high.
2) Zinc oxide arrester is based on the high and low voltage requirements, using different cross-sectional areas, different thicknesses and different amounts of zinc oxide sheets, installed in porcelain sleeves, sealed with nitrogen and sealed. Its working principle is that in the high-voltage output, if lightning strikes, the resistance of the zinc oxide sheet becomes small, the large current is short-circuited to the ground, and the transmission line is protected. If the leak causes no pressure difference between the inside and the outside, external humid gas may enter, which may damage the characteristics of the zinc oxide sheet and cause an explosion.
3) In the power industry, power plant leak detection, high-voltage transformers, high-voltage capacitors, high-voltage switch tubes and other components are also correspondingly used æ°¦ mass spectrometer leak detectors, using different methods for leak detection.
(3) Electronics industry
Microwave launch tubes, tubes, transistors, integrated circuits, sealed relays, various types of sensors, cardiac pacemakers.
(4) Vacuum industry, instrument and instrument industry
Pipes, joints, valves, bellows, various vacuum pumps, various exhaust units, electron mirrors, mass spectrometers, electron beam ion velocity exposure machines, laser shaft separators, high energy accelerators, medical accelerators, irradiation accelerators, coating machines, films Vacuum gauge.
(5) Nuclear industry
Uranium separation device, storage device, nuclear power generation device.
(6) Refrigeration industry
Refrigerators, air conditioners, lithium bromide refrigeration units, automotive air conditioners, evaporators, condensers, retractors, cryogenic storage tanks.
(7) stainless steel insulation vessel
Vacuum flasks, bottles, pots, lunch boxes, etc.
(8) Other
According to Japanese article, in the Japanese automobile manufacturing industry, more than 30 parts have been leak-detected using a helium mass spectrometer leak detector to solve the sealing problem. These include hydraulic systems, brake systems, steering systems, suspension systems, and even automotive hubs.
There are still many leak detection areas to be developed, but due to the constraints of ideas and funds, and many other reasons, the old and relatively backward methods have been used in many areas to deal with leakage problems. Product qualification rate and production efficiency are low. In a sense, this way of working restricts the development of productivity. Therefore, for vacuum professional technicians, especially those engaged in the development of vacuum equipment and the production of helium mass spectrometer leak detectors, we should make further efforts in the application and promotion of helium mass spectrometer leak detectors, and strive to promote the development of vacuum technology in China. .