Experimental Study on Vacuum Control Method for Paschen Tests of the Superconducting Magnet Mockup

In order to verify the integrity of the insulation of a superconducting magnet, the Paschen test is needed to perform on the insulation after its manufacture. The vacuum vessel for the Paschen test is required to keep for an adequately long time under the pressure values of different degrees. To achieve the low pressure in the vacuum vessel, isolating the pumping unit from the vessel is not applicable as degassing inside the vessel will eventually ruin the pressure. Therefore, one dynamic balance control system for low pressure control is designed. The feature of the system is adjusting the opening of intake valve by proportional-integral-differential control system automatically, while the vacuum pump is working constantly. The results show the dynamic balance control system can keep the pressure values of 1 ± 0.05, 10 ± 0.15, 100 ± 0.2, and 1000 ± 0.5 Pa, respectively, and the holding time of each vacuum degree is more than 2 h, which satisfies the basic vacuum requirement for the Paschen test of the tested magnet mockup sample, and can also be extended to the Paschen test on the insulation of future actual superconducting magnet.