The development history of ultra-high vacuum equipment:
Ultra-high vacuum technology is an emerging technology developed over the past four decades. At the beginning, when the cold cathode vacuum gauge was calibrated, the vacuum chamber of the PVD ultra-high vacuum equipmentwas completely immersed in liquid helium to reach a vacuum pressure environment of 10⁻¹²Pa.
In 1963, the space simulation container was equipped with a solar simulation system, using a helium refrigerator, using circulating helium to cool the simulation space to 20K, reaching a vacuum of 5X10⁻¹¹pa. Later, the National Research Corporation of the United States established a 10⁻¹²Pa ultra-high vacuum equipment, which was cooled to 4.2K with liquid helium, and the intermediate sandwich wall was cooled with liquid helium.
In 1965, Goddard Space Flight Center used cryogenic adsorption pumps with molecular sieves on liquid ammonia plates to build a space simulation chamber. It is estimated that the vacuum pressure environment can reach 10⁻¹²Pa.
In 1966, Columbia University established an ultra-high vacuum device with a molecular weight of 254nm (10 inches) in diameter. Due to the use of molecular sedimentation design, the device can perform simulation tests in a vacuum pressure environment of 10⁻¹⁰Pa. Of the above five ultra-high vacuum systems, except for the first one that is made of glass, the rest are all made of metal, and they all use a 4.2K or 20K low temperature environment. This low-temperature environment is not achievable by ordinary laboratories. Even with such conditions, the operating cost of the equipment is very high. This may be one reason why the development and application of ultra-high vacuum technology is limited. In order to solve this contradiction, people have been seeking new and easier ways to obtain ultra-high vacuum.
In 1968, foreign countries used liquid helium to freeze titanium sublimation traps to obtain a vacuum pressure environment of less than 10⁻¹¹Pa. As a result, the temperature used to obtain ultra-high vacuum is increased from 4.2K or 20K to 77.4K, which provides favorable conditions for the promotion of ultra-high vacuum technology.
After 1970, scientists in the Soviet Union carried out technical research on the acquisition of ultra-high vacuum through the two main methods mentioned above, and reached a vacuum pressure environment level of 10⁻¹⁰Pa~10⁻¹¹pa.
In 1985, the liquid nitrogen cryogenic sublimation trap and molecular precipitation technology used by my country's Aerospace Lanzhou Physics Institute achieved an ultra-high vacuum of 410⁻¹¹Pa vacuum pressure environment in a vacuum chamber with a diameter of 400mm and 500mm.
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