Global Orbit Correction and SOFB

Global closed orbit correction in the SLS storage ring is based on the Singular Value Decomposition (SVD) technique which makes ``Most Effective Corrector'' and ``MICADO'' like long range correction schemes obsolete. For the horizontal orbit correction it is crucial to take into account path-length effects by correcting off-energy orbits with the RF frequency. The difference of the original orbit and the SVD fitted off-energy part, with a deviation of dP/P corresponding to a frequency change df, is submitted to the orbit correction.
Since the beginning of the commissioning, this scheme has been successfully applied to perform operator induced corrections. Due to the modularity of the beam dynamics software environment [4], thoroughly tested software components could be reused to implement a Slow Orbit Feedback (SOFB). In this case the operator is ``replaced'' by a client program ``Feedback Client'' which initiates an orbit correction at a given frequency (see Fig. 1).

Figure: Schematic View of the SOFB: the ``Feedback Client'' on the `` Model Server'' level replaces the operator driven GUI ``oco Client'' on the `` Console'' level. The client gets BPM data from the ``BPM Server'', asks the ``TRACY Server'' for the corresponding model predicted corrector settings and applies the correction through the ``CDEV Server''