Compensation of the beam dynamics effects caused by the extraction lambertson septum of the higs booster
As part of the high intensity gamma-ray source (HIGS) upgrade, the booster synchrotron has been built and commissioned in 2006. It ramps the electron beam between 0.24 and 1.2 GeV for top-off injection into the Duke storage ring. The booster has vertical injection/extraction which uses symmetrical schemes with a bumped orbit. The injection/extraction kickers and corresponding septum magnets are located in the opposite straight sections of the booster ring separated by about 1/4 of the vertical betatron wave. Due to the non-ideal properties of the magnetic material, the magnetic field leaks out into the stored beam chamber, which results in orbit distortion, tune and chromaticity shifts, and change of coupling. The dynamics impacts due to the leaked septum fields have been successfully compensated to achieve good injection efficiency.