Design and thermal analysis of the BPM-bellows assembly front-end photon block for Hefei Advanced Light Facility

The BPM-bellows front-end photon block with ellipse cross-sections has been designed for Hefei Advanced Light Facility (HALF). Such structure has lower longitudinal coupling impedances than the photon block with commonly-used circle cross-sections. In addition, two types of cooling structures have been designed, which are shared water-cooling pipe (cooling structure 1, CS1) and independent water-cooling tank (cooling structure 1, CS2), respectively. The CS1 is simple and space-saving, while the CS2 has better heat dissipation capability. In order to calculate power density on complex light-receiving surfaces, the Monte Carlo simulation tool, Synrad, was applied. By building finite element models and importing power density data from Syrand, the temperature and thermal stress distributions of photon blocks with two different cooling structures were calculated. The thermal analysis indicates that the maximum temperature (37.73 degrees C) is located at CS1, but the maximum stress (16.28 MPa) is on CS2 due to the difference in structure and heat dissipation capability. Moreover, the maximum temperature and thermal stress values are far below the material criteria of CuCrZr. Therefore, the simple and space-saving CS1 is more suitable for HALF, which can reduce manufacturing costs and better satisfy the compact layout in the storage ring.