Correction of Closed Orbit and Dispersion Function in the Electron Storage Ring

Abstract：

In electron storage ring, the distortion of closed orbit and dispersion, due to inaccuracies of magnets manufacture and misalignment, will cause a series of negative effects, such as tune-shift, distortion of optic function, decrease of dynamic aperture, and decrease of luminance et al. Previous work mainly concentrated on the correction of closed orbit, recently a method to correct orbit and dispersion simultaneously is developed to improve the performance of storage ring, and adopted by some accelerator labs. At the same time, the beam-based-alignment is adopted to let beam pass through the center of magnets instead of vacuum chamber, so the base for correction is also the center of magnets. This paper introduces the feasibility study of realizing correction of closed orbit and dispersion, by using singular value decomposition of response matrix, at Hefei Light Source storage ring. The simulation study shows that, the rms. value of closed orbit distortion is less than 0.1 mm, and dispersions at vertical plane and dispersion-free region at horizontal plane basically disappear after correction.