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

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.