Abstract:
The Hefei Advanced Light Facility (HALF), which includes an injector and a Diffraction Limited Storage Ring (DLSR), needs ultrahigh vacuum environment to satisfy the lifetime of beam. The small-diameter vacuum chamber coated with NEG (Non-Evaporable Getter) not only saves space, but also has a high pumping speed, which can well meet the demand of obtaining ultra-high vacuum in diffraction-limited devices. The NEG films need to be activated at a certain temperature to get the pumping speed. Therefore, the NEG film activation method and process is important to ensure the safety of the other system components, such as the magnets. Based on the appropriate activation temperature of the coated NEG films, a temperature analysis model was applied to simulate the temperature distribution of the NEG coated vacuum chamber and the magnet during in-situ activation at the temperatures of 180 ℃ and 200 ℃, respectively. The oxygen-free silver bearing copper (OFS) vacuum tubes were baked out by polyimide (PI) heaters and the temperature of the tube and the magnet pole was measured. The maximum temperature measured at the magnet pole was about 40 ℃, which confirmed the safety of the quadrupole magnet. This work will be a solution and basis of in-situ activation of the NEG-coated vacuum chamber in the Hefei Advanced Light Facility.