• J.M. Weber, M.J. Chin, C. Steier, E.C. Williams
  LBNL, Berkeley, California

Funding: This work was supported by the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.

The Advanced Light Source (ALS) is a third generation synchrotron light source that has been operating since 1993 at Berkeley Lab. Recently, the ALS was upgraded to achieve Top-Off Mode, which allows injection of 1.9GeV electron beam into the Storage Ring approximately every 30 seconds. Modifications required for Top-Off operation included replacing the booster dipole and quadrupole magnet power supplies to increase the peak booster beam energy from 1.5GeV to 1.9GeV. Each new power supply was originally controlled by an analog controller that performs the current feedback loop and, in concert with other modules in the control chassis, determines the output of the ramped power supply. The new digital power supply controller performs the current feedback loop digitally to provide greater output stability and resolution. In addition, it provides remote monitoring of feedback loop signals, interlocks, and status signals, as well as remote control of the power supply operation via Ethernet. This paper will present the ALS Digital Power Supply Controller module requirements and design.

• C. Steier, B.J. Bailey, K.M. Baptiste, W. Barry, A. Biocca, W.E. Byrne, P.W. Casey, M.J. Chin, R.J. Donahue, R.M. Duarte, M.P. Fahmie, J. Gath, S.R. Jacobson, J. Julian, J.-Y. Jung, A.M. Kritscher, S. Kwiatkowski, S. Marks, J.P. McKean, R.S. Müller, H. Nishimura, J.W. ONeill, G.J. Portmann, S. Prestemon, D. Robin, S.L. Rossi, F. Sannibale, T. Scarvie, D. Schlueter, B. Shuman, A.Z. Smith-Baumann, G.D. Stover, CA. Timossi, W. Wan, T. Warwick, J.M. Weber, R.P. Wells, E.C. Williams
  LBNL, Berkeley, California

Funding: This work was supported by the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC02-05CH11231.

The upgrade of the Advanced Light Source to enable top-off operation has been ongoing for the last four years. Activities over the last year have centered around radiation safety aspects, culminating in a systematic proof that top-off operation is equally safe as decaying beam operation, followed by commissioning and full user operations. Top-off operation at the ALS provides a very large increase in time-averaged brightness to ALS users (by about a factor of 10) as well as improvements in beam stability. The presentation will provide an overview of the radiation safety rationale, commissioning results, as well as experience in user operations.