What is Ultra-High Vacuum?

According to molecular energy, vacuum space can be divided into four types: near-field vacuum, thermal vacuum, low-temperature plasma vacuum, and high-energy particle vacuum. The average energy of particles flying in each vacuum is 5 eV, O.3 eV, 100 eV, and 40 TeV. The nuclear fusion plasma prepared in a vacuum chamber is not a low-temperature plasma (10 keV).

Ultra-high vacuum

(Vacuum type)

Right!

Divided by molecular energy, vacuum space can be divided into four types, near field

According to the pressure level, the vacuum type is divided into low vacuum, medium vacuum, high vacuum and ultra high vacuum (UHV). Often the pressure is considered

The following vacuum is called ultra-high vacuum. This means that the number of molecules in a unit volume is only 1 / 1,000,000,000,000 of normal atmospheric pressure.

Ultra-high vacuum is commonly used in surface science because molecules in the air adhere to solid surfaces exposed to the air and alter the surface characteristics of the solid. Even though

In the high vacuum, a layer of molecules will adhere to the bare solid surface within 3 seconds. However, in ultra-high vacuum, the same process will take several hours to complete, which can ensure the normal development of surface characteristics research ^[1-2] . Under such ultra-low pressure, the average free path of a single molecule can reach 40Km. In other words, almost all molecules in the vacuum cavity will collide with the cavity wall.

According to molecular energy, vacuum space can be divided into four types: near-field vacuum, thermal vacuum, low-temperature plasma vacuum, and high-energy particle vacuum.

The average energy of particles flying in each vacuum is 5 eV, O.3 eV, 100 eV, and 40 TeV. The nuclear fusion plasma prepared in a vacuum chamber is not a low-temperature plasma (10 keV).

Surface scientists and surface analysis instrument engineers have been studying the near-field area. In the processing of substrate materials, including global environmental technology, people mainly study thermal vacuum.

Materials surfacers use knowledge of near-field regions, thermal vacuum, and low-temperature conventional plasma vacuum (excluding ion implantation).

The history and current status of ultra-high vacuum, ultra-high vacuum, and their R & D technology are well discussed in the special issue of JVSTA V01.21, Supplement No. 5 published by PARadhead, JPHobson, and HFDylla.

The ultra-high vacuum technology in the surface treatment system is based on research and development technology, and it is diverse in industrial applications. Considering economic factors, a large number of special materials are used in practical applications.

In industry, ultra-high vacuum technology is a branch of ultra-clean technology (UCL), and any materials and processes should be kept clean. The first step in ultra-high vacuum processing is surface degassing and measurement. We first discuss the molecular dynamics basis of ultra-high vacuum systems.