• V. Popov, S.M. Hartman, S. Mikhailov, O. Oakeley, P.W. Wallace, Y.K. Wu
  DU/FEL, Durham, North Carolina

The next generation electromagnetic OK-5/Duke storage ring FEL wigglers require three 3kA/70V power supplies with current stability about 20 ppm and current ripples less than 20ppm in their full operating range. Duke FEL Laboratory acquired three out-of-service thyristor controllable power supplies (Transrex, 5kA/100V) which was built almost 30 years ago. The existing archaic firing circuit, lack of any output voltage filtering and outdated DCCT, would not be able to meet the above requirements.To deliver the desirable high performance with very limited funds, all three T-Rex power supplies have been completely rebuilt in house at DFELL. Modern high stability electronic components and a Danfysik DCCT with a high current stability have been used. New symmetrical firing circuit, efficient passive LC filter and reliable transformer-coupled active filter are used to reduce output current ripples to an appropriate level. At the present time, the first refurbished power supply in operation since August, 2004 with good overall performance. The power supply testing results of this unit will also be presented in this paper.

• V. Popov, S.M. Hartman, S. Mikhailov, O. Oakeley, P.W. Wallace, Y.K. Wu
  DU/FEL, Durham, North Carolina

The on-going Duke storage ring upgrades and the development of a new booster synchrotron injection require more than 100 units of high performance unipolar and bipolar trim power supplies in the current range of -15A to +15A. However, most of the trim power supplies on the market do not deliver two critical performance features simultaneously: a high current stability and a low current noise.An in-house trim power supply development program is then put in force to design, fabricate, and test low cost linear power supplies with current stability about 100 ppm and current ripples less than 100 ppm in a broad band. A set of unipolar power supplies (0-12A) have been designed, fabricated and successfully tested. Since August, 2004 they have been used in storage ring operation with excellent performance. The prototype of bipolar power supplies (± 15 A) has been designed and tested as well. The main design principles and their performance results of both unipolar and bipolar supplies will be presented in this paper.

• Y.K. Wu, M.D. Busch, M. Emamian, J.F. Faircloth, J. Gustavsson, S.M. Hartman, C. Howell, M. Johnson, J. Li, S. Mikhailov, O. Oakeley, J. Patterson, M. Pentico, V. Popov, V. Rathbone, G. Swift, P.W. Wallace, P. Wang
  DU/FEL, Durham, North Carolina

The Duke FEL lab operates a unique UV/VUV storage ring FEL and an FEL driven, nearly monochromatic, highly polarized, high intensity Compton gamma-ray source. The Duke storage ring light source is undergoing several phases of upgrade in order to significantly improve light source capabilities and performance. The 2004 phase included an upgrade of the RF system with a high-order mode damped RF cavity and a new 34 meter long straight section lattice to host new FEL wigglers in the next phase. This upgrade was completed in August 2004 and storage ring and light source commissioning were completed in November 2004. This paper will provide an overview of this upgrade project and report our commissioning experience of the storage ring and light sources.

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

This paper presents the current status of the booster synchrotron for the Duke FEL storage ring. The booster will provide full energy injection into the storage ring in a wide energy range from 0.27 to 1.2 GeV. When operating the Duke FEL storage ring as the High Intensity Gamma Source (HIGS) to produce gamma photons above 20 MeV with Compton scattering, continuous electron loss occurs. The top-off mode operation of the booster injector will enable the continuous operation of the HIGS facility by replenishing the lost electrons. The design requirement for a compact booster with the single bunch extraction capability remains a challenge for the machine development. Presently, the booster project is in the installation phase. The magnetic elements, vacuum chambers, injection and extraction kickers have been fabricated in the Budker Institute of Nuclear Physics, Russia. The diagnostic and control system is being developed in the FEL lab, Duke University. The commissioning of the booster synchrotron is planned for fall 2005.

• G.Y. Kurkin
  BINP SB RAS, Novosibirsk
• S.M. Hartman, S. Mikhailov, Y.K. Wu
  DU/FEL, Durham, North Carolina
• I.P. Pinayev
  BNL, Upton, Long Island, New York

A dedicated booster synchrotron is being constructed at the Duke FEL Laboratory to provide full energy injection into the main electron storage ring. A new timing system has been developed to coordinate the injection of electron bunches from the linac to the booster, the ramping of energy in the booster, and extraction of bunches into the main ring. The timing system will allow the extraction of any bunch in the booster into any selected bucket in the main ring to provide top-off injection for any of the various operational bunch patterns of the main ring. A new master oscillator has also been developed for the RF system of the booster. The oscillator may be tuned independently or phase-locked to the master oscillator of the main ring. The issues of the soft phase locking process of the new master oscillator are discussed. The timing system and new oscillator have been fabricated and tested and are ready for operation.

• S.M. Hartman, S. Mikhailov, Y.K. Wu
  DU/FEL, Durham, North Carolina

The Duke FEL is developing a booster synchrotron to provide full energy injection into the Duke electron storage ring. In this paper, we describe the development of the control system for the booster. Requirements include the competing needs of simple and reliable turn-key operation for the machine as a booster; and the sophistication and flexibility of operation of the machine as a storage ring for commissioning, machine studies and as a light source. To simplify operations and machine studies, the high level controls will present the system in terms of the physics quantities of the accelerator, allowing a tight integration between the physics model and the low level hardware control, as we have previously implemented for Duke storage ring.

• S.M. Hartman
  DU/FEL, Durham, North Carolina

We analyze some recent experiences with commercial off the shelf (COTS) I/O hardware modules, comparing manufacturer specifications with our in-house measurements. Discrepancies between quoted specifications and measured performance under accelerator laboratory conditions have been observed. In some cases, design or manufacturing faults have been found which could have impact on the overall performance of the accelerator.