Top-up

Top-up at the ESRF

Top up was implemented in November 2017 at the ESRF to refill the storage ring more frequently (20 min). Previously, the refill took place every 12 hours. This results in a much higher integrated current over 24-hour period, providing users with better beam stability, low vertical emittance in all filling modes (with correspondingly higher brilliance and resolution) and a nearly constant beam current.

Since the restart of EBS, top-up took place every 1 hour due to the strong perturbations at injection time which are detrimental to the nanofocus beamlines.

New injection techniques are under investigation to reduce it allowing more frequent injections.

With the current configuration the beam still needs to be vertically blown-up in order to get reasonable lifetime during the beam decay between two injections.
When time structure mode needs high purity level, the cleaning is done in the booster before being injected in the storage ring.
Optionally, an additional cleaning can be done in the storage ring on request. Today, top-up mode can be performed in all modes, even those including several switches of the timing file during the top-up!