Speaker
Description
Designing a low emittance ring is generally achieved at the cost of a lower beam lifetime. To ensure a relatively constant current in the ring it is therefore compulsory to use a top-up refill scheme with frequent injections. Unfortunately injections are not completely transparent for users, the pulsed magnets (septa or kickers) induce some perturbation of the beam motion (closed orbit) and beam parameters which is then converted in an emittance increase lasting a few damping time.
In the present machine we have drastically reduced the perturbation at injection thanks to the improvement of the injection kicker system and the addition of several active disturbance cancellation systems. For the ESRF-EBS the perturbation will be reduced even further with a better design of the injection cell. The remaining perturbations to be compensated for will be smaller and it is expected that the systematic perturbation could be cancelled out with a feed-forward compensation. Non-systematic perturbation (due to kickers firing individual jitter) cannot be addressed with a feed-forward scheme and may need a dedicated feedback loop.
