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TY - CONF AU - Mirza, S.H. AU - Forck, P. AU - Klingbeil, H. AU - Singh, R. ED - Koscielniak, Shane ED - Satogata, Todd ED - Schaa, Volker RW ED - Thomson, Jana TI - Effect of Model Errors on the Closed Orbit Correction at the SIS18 Synchrotron of GSI J2 - Proc. of IPAC2018, Vancouver, BC, Canada, April 29-May 4, 2018 C1 - Vancouver, BC, Canada T2 - International Particle Accelerator Conference T3 - 9 LA - english AB - A fast closed orbit feedback system (bandwidth in the order of 1 kHz) is under development at the GSI SIS18 synchrotron for the orbit correction from injection to extraction including the acceleration ramp. The static process model, represented as the orbit response matrix (ORM), is subjected to the systematic optics changes during ramp e.g. beta function and phase advance variations at the locations of BPMs and steerers. In addition to these systematic variations, model mismatches may arise from dipole and quadrupole magnet errors, space charge dependent tune shift as well as BPM and steerer calibration errors. In this contribution, the effects of these model errors on the closed orbit correction are investigated which is necessary for the robust stability analysis of the feedback controller. For the robustness tests, the traditional SVD-based matrix pseudo-inversion is compared to a Fourier-based analysis. The results are achieved by detailed simulations in MADX. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2080 EP - 2083 KW - quadrupole KW - synchrotron KW - closed-orbit KW - controls KW - focusing DA - 2018/06 PY - 2018 SN - 978-3-95450-184-7 DO - 10.18429/JACoW-IPAC2018-WEPAK003 UR - http://jacow.org/ipac2018/papers/wepak003.pdf ER -