Abstract: Four refrigerator cooled cryopumps (DN1250 LN₂) were designed and manufactured by BISEE. The pumps were used in space environment simulation system to meet the demand of the high vacuum in thermal vacuum test. The design and test method for pumping speed, cool down time and crossover were introduced in this paper. A test system was built to test the main performance of the cryopumps. The experimental results show that the pumping speed for N₂ of the pump is up to 57000 L/s, the cool down time is about 330min, and the crossover is over than 3.0 ×10⁵Pa·L.

Key words: cryopump, pumping speed, cool down time, crossover, test method