• V. Popov, M. D. Busch, S. M. Hartman, S. F. Mikhailov, O. Oakeley, P. W. Wallace, Y. K. Wu
  FEL/Duke University, Durham, North Carolina

A booster synchrotron has been recently commissioned at Duke University as part of the High Intensity Gamma-ray Source (HIGS) upgrade. All dipole and quadrupole magnets are fed by the same power supply in order to facilitate synchronization. A 500kW retired thyristor controlled power supply has been completely rebuilt to provide high accuracy ramping of current in the range between 150A and 700A in a 1.3 sec repetition cycle. Reproducibility of current at extraction energy is better than 0.1% for entire operational range of energy. Conflict of a fast ramping operation and a magnet protection in the case of emergency shutdown was resolved using additional thyristor switches. All trim power supplies involved in ramp have been matched with the main power supply for the time response and voltage range. The injection and extraction schemes require rapidly ramping Y-correctors. The required peak power about 4 kW in these correctors is provided by a combining a low voltage DC power supply and a pulse boosting circuit. We present the challenges of designing and developing booster power supply system. And also we report measured performance and operational experience in this paper.

• S. F. Mikhailov, M. D. Busch, M. Emamian, S. M. Hartman, Y. Kim, J. Li, V. Popov, G. Swift, P. W. Wallace, P. Wang, Y. K. Wu
  FEL/Duke University, Durham, North Carolina
• O. Anchugov, N. Gavrilov, G. Y. Kurkin, Yu. Matveev, D. Shvedov, N. Vinokurov
  BINP SB RAS, Novosibirsk
• C. R. Howell
  TUNL, Durham, North Carolina

A booster synchrotron has been built and recently commissioned at Duke University Free Electron Laser Laboratory (DFELL) as part of the High Intensity Gamma-ray Source (HIGS) facility upgrade. HIGS is developed collaboratively by the DFELL and Triangular Universities Nuclear Laboratory (TUNL). The booster will provide top-off injection into the Duke FEL storage ring in the energy range of 0.27 - 1.2 GeV. When operating the Duke storage ring to produce high energy Compton gamma ray beams above 20 MeV, continuous electron beam loss occurs. The lost electrons will be replenished by the booster injector operating in the top-off mode. The compactness of the booster posed a challenge for its development and commissioning. The booster has been successfully commissioned in 2006. This paper reports experience of commissioning and initial operation of the booster.

• V. Popov, M. D. Busch, S. M. Hartman, J. Li, S. F. Mikhailov, P. W. Wallace, P. Wang, Y. K. Wu
  FEL/Duke University, Durham, North Carolina
• G. Y. Kurkin
  BINP SB RAS, Novosibirsk

First operational experience has been gained with the linac and booster diagnostic system during the commissioning of the booster synchrotron at Duke University. Beam charge measurements are provided by Faraday cups, Integrated Current Transformers (ICT) and Modular Parametric Current Transformer (MPCT). Beam position monitoring is based on BPM system delivered from Bergoz company. Betatron tune measurements use synchrotron radiation (SR) and are different for two modes of operation: stored beam and energy ramping. Transverse profile and temporal beam structure monitoring employ insertable screens, CCD cameras, striplines and dissector. The diagnostics provided good understanding of electron beam behavior and allowed to adjust important beam parameters within design specifications. An overview of the diagnostic instrumentation of the Duke linac and booster synchrotron is given along with measurement examples and discussion of operational experience.