• P. Towalski, P. Hartmann, S. Khan, D. Schirmer, G. Schmidt, G. Schünemann, T. Weis
  DELTA, Dortmund

The beam orbit of the 1.5GeV electron storage ring DELTA showed a variety of beam distortions with a pronounced frequency spectrum mostly caused by girder movements and ripples of the magnet power supplies. In order to enhance the orbit stability at least up to 300 Hz bandwidth a global fast orbit feedback is under consideration. As a prototype an FPGA based local fast orbit feedback at a 10 kHz data acquisition rate has been developed. The digitized orbit data are distributed from I-Tech Libera and Bergoz MX-BPMs to an FPGA board via a fibre interconnected network based on the Diamond Communication Controller [*]. The correction algorithm is written in VHDL and the corrections are applied with digital power supplies connected to the FPGA board through RS485 links. The first operational tests of the system achieved an effective damping of orbit distortions up to 350 Hz. The paper will give an overview on the layout of the FPGA based local orbit feedback system, will report on the results of the measured uncorrected orbit distortions at DELTA and the stability enhancements that could be achieved by the local feedback system.

* I. S. Uzun et al., "Initial Design of the Fast Orbit Feedback System for
Diamond Light Source", Proc. 10th ICALEPCS

• C. Böhme
  UniDo/IBS, Dortmund
• J.L. Conradie
  iThemba LABS, Somerset West
• J. Dietrich, V. Kamerdzhiev
  FZJ, Jülich
• T. Weis
  DELTA, Dortmund

Scintillation is one of the outcomes of beam interaction with residual gas. This process is utilized for non-destructive beam profile monitoring. Test bench measurements at various gas compositions and pressures as well as ones with the circulating proton beam at COSY-Juelich were performed. This was done using a single large photocathode PMT to estimate the photon yield. A multichannel photomultiplier was used along with a lens system to monitor the ion beam profile. Experimental results are presented and the challenges of the approach are discussed.

• G. Schünemann, P. Hartmann, D. Schirmer, P. Towalski, T. Weis, K. Wille
  DELTA, Dortmund
• P. Marwedel
  TU Dortmund University, Dortmund

Orbit stability at the 1.5 GeV electron storage ring DELTA is currently achieved via a global slow orbit feedback system at a data acquisition rate of 10 Hz. The system is based on analog Bergoz MX-BPMs and I-Tech Libera digital BPMs. In order to enhance the precision of the slow position measurement and in preparation for a global fast orbit feedback at a 10 kHz data acquisition rate we developed an FPGA based digital frontend for the MX-BPMs. The prototype module is taking orbit data from 4 Bergoz MX-BPMs, clocked to 40 kHz, at a rate of 10 kHz while averaging over 4 samples per clock cycle. The digitized data is distributed via the Diamond Communication Controller [*] formerly only available for Libera BPMs. Precision, fault tolerance and easy maintenance are the key aspects of this system. First operational tests in the storage ring showed that the system reveals the desired capabilities. The paper will give an overview on the layout of the FPGA-based system, will report on the results with beam and will show prospects for the further use at DELTA.

*I. S. Uzun et al., "Initial Design of the Fast Orbit Feedback System for Diamond Light Source", Proc. 10th ICALEPCS