Constant-pressure helium control device of vacuum system and constant-pressure control method

Abstract

The invention discloses a constant-pressure helium controller of a vacuum system. In the device, a helium pressure signal in the vacuum system is measured by using a vacuum gauge, the pressure signal is compared with a set value to generate a feedback signal, the heating power of a filter helium micro-leak valve (hereinafter referred to helium leak, see patent CN1479031A) is adjusted through the feedback signal, and finally the helium pressure of the vacuum system reaches the set value. The device and the method have the advantages that: the pressure signal is directly fed back by using the vacuum gauge, the heating power of a helium leak heating wire is controlled through the feedback signal and the permeability of the helium is adjusted so that the device realizes direct control of the helium pressure in the injection vacuum system and is not affected by environmental temperature, pumping rate of a vacuum pump and helium pressure difference change on two sides of the helium leak; and the controller realizes control of the heating power, namely helium permeability of the helium leak by using pulse width modulation, and has high control sensitivity of the helium pressure in the injection vacuum system.

Description

technical field [0001] The invention relates to the fields of electronic technology and vacuum technology, and more specifically relates to a device and method for injecting constant-pressure helium into a vacuum system, mainly used for injecting constant-pressure helium into the vacuum system. Background technique [0002] In order to study the physical properties of particles such as atoms, molecules or ions, some experiments must be carried out in a vacuum system with an ultra-high vacuum degree. The vacuum system mainly includes a vacuum sealed cavity for opening and sealing and a vacuum gauge for measuring the vacuum degree. In many physical experiments carried out in vacuum, in order to better study the physical properties of particles such as atoms, molecules or ions, it is necessary to cool the particles with higher temperature or thermal kinetic energy. A simple and reliable method is to inject high-purity inert gas-helium into the vacuum system, and reduce the ther...

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Problems solved by technology

[0003] At present, the method of injecting high-purity helium into the vacuum system is to inject the helium in the cylinder into the vacuum system by using a filter-type helium micro-leakage valve (also known as helium leak) (see patent CN1479031A). The temperature control of the leak is used to control the penetration rate of helium into the vacuum system. The disadvantage of this method is that when the external environment temperature changes or the pumping rate of the vacuum pump that maintains the vacuum system changes, the pressure of helium in the vacuum system also changes. Changes will occur, and due to the existence of the temperature control system, the helium leak still injects helium into the system at the original permeation rate, so the stability of the helium pressure in the vacuum system cannot be guaranteed

At the same time, because the helium permeability is not only related to the temperature of the helium leak, but also related to the pressure difference of helium on both sides of the helium leak (the greater the pressure difference, the greater the permeability). The difference gradually decreases, the helium permeability decreases, and the helium pressure in the vacuum system decreases accordingly, and the stability of the helium pressure in the vacuum system cannot be guaranteed.

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