Accelerator Technology

Power Supplies and Conversion

Paper Title Page
WPAE058 High Voltage Measurements on Nine PFNs for the LHC Injection Kicker Systems 3402
  • M.J. Barnes, G.D. Wait
    TRIUMF, Vancouver
  • L. Ducimetière
    CERN, Geneva
  Funding: National Research Council of Canada

Each of the two LHC injection kicker magnet systems must produce a kick of 1.3 T.m with a flattop duration variable up to 7.86 microseconds, and rise and fall times of less than 900 ns and 3 microseconds, respectively. A kicker magnet system consists of four 5 Ohm transmission line magnets with matching terminating resistors, four 5 Ohm Pulse Forming Networks (PFN) and two Resonant Charging Power Supplies (RCPS). Nine PFNs, together with associated switch tanks, and dump switch terminating resistors have been built at TRIUMF and all have been tested at high voltage (54 kV) to ensure that the performance is within specification. This paper describes the HV measurements, compares these results with low voltage measurements and analyses the pulse performance of the PFNs. The measurements are compared with results from PSpice simulations and small discrepancies between the predictions and measurements are explained.

WPAE060 Programmable Power Supply for AC Switching Magnet of Proton Accelerator 3508
  • S.-H. Jeong, H.S. Han, Y.G. Jung, H.-S. Kang, H.-G. Lee, K.-H. Park, C. K. Ryu, H.S. Suh
    PAL, Pohang, Kyungbuk
  • H.H. Lee
    UU, Gyeongju
  Funding: Ministry of Science and Technology.

The 100-MeV PEFP proton linac has two proton beam extraction lines for user’ experiment. Each extraction line has 5 beamlines and has 5 Hz operating frequency. An AC switching magnet is used to distribute the proton beam to the 5 beamlines, An AC switching magnet is powered by PWM-controlled bipolar switching-mode converters. This converter is designed to operate at ±350A, 5 Hz programmable step output. The power supply is employed IGBT module and has controlled by a DSP (Digital Signal Process). This paper describes the design and test results of the power supply.

WPAE061 LC Filter for High Accuracy and Stability Digital MPS at PLS 3550
  • S.-C. Kim, J. Choi, K.M. Ha, J.Y. Huang
    PAL, Pohang, Kyungbuk
  Funding: Work supported by the Ministry of Science and Technology, Korea.

High accuracy and stability digital power supply for magnet is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second consists of IGBT driver and four quad IGBT switch, and the third is LC output section. AC input voltage of power supply is 3-phase 21V, output current is 0 ~ 150 A dc. Switching frequency of IGBT is 25 kHz. The output current of power supply has very high accuracy of 100 mA step resolution at full range and the stability of ± 1.5 ppm for short term and ± 5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.

WPAE062 AC Power Supply for Wobbler Magnet of the MC-50 Cyclotron 3576
  • Y.-S. Kim, J.-S. Chai
    KIRAMS, Seoul
  • C.W. Chung, H.-G. Lee, W.W. Lee, K.-H. Park
    PAL, Pohang, Kyungbuk
  • B.-K. Kang
    POSTECH, Pohang, Kyungbuk
  The MC-50 cyclotron (k=50) produces the ion beam for nuclear physics, chemistry, and applied researches in Korea. It has a small beam diameter with Gaussian beam shape, whereas many users want a beam irradiation on a large target. A wobbler magnet and an AC power supply were designed and constructed to meet the users’ requirement. The power supply has two independently operating channels for the vertical and horizontal coils of the wobbler magnet. The frequency of the AC power supply for both coils is programmable from 1 to 20 Hz in a step of 1 Hz, and the maximum rms output current is 12 A. Various properties of the power supply and experimental results are given in the paper.  
WPAE063 CERN-PS Main Power Converter Renovation: How To Provide and Control the Large Flow of Energy for a Rapid Cycling Machine? 3612
  • F. Bordry, J.-P. Burnet, F. Voelker
    CERN, Geneva
  The PS (Proton-Synchrotron) at CERN, which is part of the LHC injector chain, is composed of 101 main magnets connected in series. During a cycle (about 1 second), the active power at the magnet terminals varies from plus to minus 40 MW. Forty years ago, the solution was to insert a motor-generator (M-G) set between the AC supply network and the load. The M-G set acts as a fly-wheel with a stored kinetic energy of 233 MJ. The power converter is composed of two 12-pulse rectifiers connected in series. A renovation or replacement of the installation is planned in the near future as part of the consolidation of the LHC injectors. This paper presents a first comparison of technical solutions: - a direct connection to the 400 kV mains; - a kinetic energy storage system either by the existing or by a new “state of the art” M-G set; - a new local inductive or capacitive energy storage system. All these solutions need new power electronics equipment, which should be based on proven industrial topologies, techniques and components. The related studies will address the challenge of controlling by a modern power converter with local energy storage the positive and negative flow of energy to a rapid cycling accelerator load.  
WPAE064 "Fast-Slow" Beam Chopping for Next Generation High Power Proton Drivers 3635
  • M.A. Clarke-Gayther
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  Funding: Work supported by CCLRC/RAL/ASTeC and by the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395).

A description is given of two "state of the art" high voltage pulse generator systems, designed to address the requirements of a fast beam chopping scheme for next generation high power proton drivers.[1] Measurements of output waveform and timing stability, for fast transition short duration, and slower transition long duration pulse generators, are presented.

[1]M. A. Clarke-Gayther, "A Fast Beam Chopper for Next Generation High Power Proton Drivers," Proc. of the ninth European Particle Accelerator Conference (EPAC), Lucerne, Switzerland, 5-9 July, 2004, p. 1449-145.

WPAE065 Jefferson Lab's Trim Card II 3670
  • T.L. Allison, H. Higgins, E. Martin, W. Merz, S. Philip
    Jefferson Lab, Newport News, Virginia
  Funding: This work was supported by DOE contract DE-AC05-84ER40150 Modification No. M175, under which the Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility.

Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) uses Trim Card I power supplies to drive approximately 1900 correction magnets. These trim cards have had a long and illustrious service record. However, some of the employed technology is now obsolete, making it difficult to maintain the system and retain adequate spares. The Trim Card II is being developed to act as a transparent replacement for its aging predecessor. A modular approach has been taken in its development to facilitate the substitution of sections for future improvements and maintenance. The resulting design has been divided into a motherboard and 7 daughter cards which has also allowed for parallel development. The Trim Card II utilizes modern technologies such as a Field Programmable Gate Array (FPGA) and a microprocessor to embed trim card controls and diagnostics. These reprogrammable devices also provide the versatility to incorporate future requirements.

WPAE066 PEP-II Large Power Supplies Rebuild Program at SLAC 3685
  • A.C. de Lira, P. Bellomo, J.J. Lipari, F.S. Rafael
    SLAC, Menlo Park, California
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.

At PEP-II, seven large power supplies (LGPS) are used to power quad magnets in the electron-positron collider region. The LGPS ratings range from 72kW to 270kW, and were installed in 1997. They are unipolar off-line switch mode supplies, with a 6 pulse bridge rectifying 480VAC, 3-phase input power to yield 650VDC unregulated. This unregulated 650VDC is then input into one (or two) IGBT H-bridges, which convert the DC into PWM 16 kHz square wave AC. This high frequency AC drives the primary side of a step-down transformer followed by rectifiers and low pass filters. Over the years, these LGPS have presented many problems mainly in their control circuits, making it difficult to troubleshoot and affecting the overall accelerator availability. A redesign/rebuilding program for these power supplies was established under the coordination of the Power Conversion Department at SLAC. During the 2004 accelerator summer shutdown all the control circuits in these supplies were redesigned and replaced. A new PWM control board, programmable logic controller, and touch panel were all installed to improve LGPS reliability, and to make troubleshooting easier. In this paper we present the details of this rebuilding program and results.

WPAE069 The APS Septum Magnet Power Supplies Upgrade 3795
  • B. Deriy, A.L. Hillman, G.S. Sprau, J. Wang
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The higher requirements for beam injection stability at the APS storage ring demand improvement of pulsed power supplies for the septum magnets. The upgrade will be performed in two stages. In the first stage we will implement a new power supply circuit with a new regulation timing sequence that will provide better voltage regulation performance. A common design was made for all of the septum magnet power supplies at the APS. The new regulation module has already been tested on both thin and thick septum magnet power supplies. This test showed that the new target for the current regulation stability, 1/2000 with less than 10-ns jitter, is achievable with this approach. In the second stage we will implement an embedded microprocessor system that will provide digitally controlled shot-to-shot current regulation of the power supply. The system comprises modules for communication with EPICS, data acquisition, and precise timing. A prototype has already been built and will also be discussed.

WPAE070 Injector Power Supplies Reliability Improvements at the Advanced Photon Source 3804
  • A.L. Hillman, S.J. Pasky, N. Sereno, R. Soliday, J. Wang
    ANL, Argonne, Illinois
  Funding: *Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

Operational goals for the APS facility include 97% availability and a mean time between unscheduled beam losses (faults) of 70 hours, with more than 5000 user hours of scheduled beam per year. To meet this objective, our focus has changed to maximizing the mean time between faults (MTBF). We have made various hardware and software improvements to better operate and monitor the injector power supply systems. These improvements have been challenging to design and implement in light of the facility operating requirements but are critical to maintaining maximum reliability and availability of beam for user operations. This paper presents actions taken as well as future plans to continue improving injector power supply hardware and software to meet APS user operation goals.

WPAE071 Power Supply for Magnet of Compact Proton and/or Heavy Ion Synchrotron for Radiotherapy 3859
  • S. Yamanaka
    NIRS, Chiba-shi
  • K. Egawa, K. Endo, Z. Fang
    KEK, Ibaraki
  A resonant type pulse power supply, for an application to a compact proton and/or heavy ion synchrotron with a several Hz repetition rate, is attractive from the view point of attaining an average beam current that is enough for the radiation therapy. Maximum ampere-turn of the dipole magnet is as large as 200 kAT to make the bending radius as small as possible. Pulse current is generated by discharging the stored energy in a capacitor bank through a pulse transformer. Moreover, the auxiliary power supply for the dipole magnets which adds the flat magnetic field (10-20μs) for the multi-turn beam-injection is being developed. The power supply for the quadrupole magnets is the high switching frequency (20 kHz × 5) switching-mode Power Supply for the adjusting tune and the tracking between the quadrupole and the dipole fields.Detailed analyses on these pulse power supplies will be presented.  
WPAE072 Installation and Testing of SNS Magnet Power Supplies 3889
  • K.R. Rust, W.E. Barnett, R.I. Cutler, J. T. Weaver
    ORNL, Oak Ridge, Tennessee
  • S. Dewan, R. Holmes, S. Wong
    IE Power Inc., Mississauga, Ontario
  • R.F. Lambiase, J. Sandberg
    BNL, Upton, Long Island, New York
  • J. Zeng
    Digital Predictive Systems Inc., Toronto
  Funding: This work was supported by SNS through UT-Batelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

This paper describes the types and quantities of magnet power supplies required for the SNS Linear Accelerator, High-Energy Beam Transport (HEBT), Ring and the Ring-Target Beam Transport (RTBT). There are over 600 magnets and more than 550 magnet power supplies. These magnet power supplies range in size from the bipolar-corrector supplies rated at 35 volts, 20 amps to the main-ring dipole supply that is rated at 440 volts, 6000 amps. The Linac power supplies have a ripple/stability specification of 1000 parts per million while the ring supplies have a specification of 100 parts per million. There are also pulsed power supplies for beam injection and beam extraction. The paper will show acceptance test results from the manufacturers as well as test results performed by the SNS magnet power supply group.

WPAE073 3 kA Power Supplies for the Duke OK-5 FEL Wigglers 3901
  • V. Popov, S.M. Hartman, S. Mikhailov, O. Oakeley, P.W. Wallace, Y.K. Wu
    DU/FEL, Durham, North Carolina
  Funding: U.S. AFOSR MFEL grant F49620-001-0370.

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.

WPAE074 Trim Power Supplies for the Duke Booster and Storage Ring 3919
  • V. Popov, S.M. Hartman, S. Mikhailov, O. Oakeley, P.W. Wallace, Y.K. Wu
    DU/FEL, Durham, North Carolina
  Funding: U.S. AFOSR MFEL grant F49620-001-0370 and HIGS Upgrade DOE grant number is DE-FG02-01ER41175.

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.

WPAE075 Compact Digital High Voltage Charger 3964
  • G. Li, Y.G. Zhou
    USTC/NSRL, Hefei, Anhui
  The operation of classical resonant circuit developed for the pulse energizing is investigated. The HV pulse or generator is very compact by a soft switching circuit made up of IGBT working at over 30 kHZ. The frequencies of macro pulses andμpulses can be arbitrarily tuned below resonant frequency to digitalize the HV pulse power. Theμpulses can also be connected by filter circuit to get the HVDC power. The circuit topology is given and its novel control logic is analyzed by flowchart. The circuit is part of a system consisting of a AC or DC LV power supply, a pulse transformer, the pulse generator implemented by LV capacitor and leakage inductance of the transformer, a HV DC or pulse power supply and the charged HV capacitor of the modulators.  
WPAE079 Dual Power Supplies for PEP-II Injection Kickers 4045
  • J. Olszewski, F.-J. Decker, R.H. Iverson, A. Kulikov, G.C. Pappas
    SLAC, Menlo Park, California
  Funding: Work supported by Department of Energy contract DE-AC03-76SF00515.

Originally the PEP-II injection kickers where powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independant power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of five since there are no long cables that have to be charged. The kickers are now independantly adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed.