ORBIT CONTROL AT THE SLS STORAGE RING

M. Böge, J. Chrin, P. Pollet, T. Schilcher, V. Schlott, PSI, Villigen, Switzerland

Abstract:

Precise orbit control is one of the crucial ingredients for stable operation of the SLS storage ring. The orbits are taken by the digital BPM system which allows beam position measurements to the sub-micron level at sampling rates of up to 4 kHz at 72 locations in the ring. Orbits are corrected with respect to a user defined reference by applying SVD techniques and a direct response matrix inversion. A slow global orbit feedback operating at correction rates of up to 1 Hz stabilizes the orbit to within $\sim$0.5 $\mu$m rms at the locations of the insertion devices. Energy drifts are automatically corrected using the RF frequency as an additional corrector, resulting in a long term energy stability of $\sigma$(dP/P) $\approx$ 10$^{-5}$. The status of a digital BPM system based fast orbit feedback running at 4 kHz sampling rate is presented.