DESIGN AND CALCULATION OF THE STRIPLINE BEAM POSITION MONITOR FOR HLS II STORAGE RING

According to the requirements of HLS II upgraded, in order to acquire the non-intercepting measurement of beam position and quadrupole component, a new stripline beam position monitor (BPM) was designed for storage ring. The BPM parameters were optimized to acquire impedence matching with characteristic impedance of the external transmission lines and the coupling coefficients between the electrodes were calculated. According to the difference/sum and log-ratio methods, the horizontal and vertical sensitivities, mapping figures and fitting polynomials wered acquired. The results showed that sensitivities using log-ratio method were bigger than those using difference/sum method. The sum signal was also simulated when beam displacement varied from (0 mm, 0 mm) to (5 mm, 5 mm), the result showed that the variation of normalized sum signal was no more than f 6%. The gaussian weighted method of a two-dimensional grid structure was used to simulate the gaussian bunch and simulate the beam transverse quadrupole component changing with position (x, y), the result showed that the beam transverse quadrupole component changed linearly with position combination (x 2 -y 2 ).