| Paper | Title | Page |
|---|---|---|
| THPP120 | Measurements on an A/D Interface Used in the Power Supply Control System of the Main Dipoles of CNAO | 3638 |
|
||
| The CNAO (the Italian Centre of Oncological Hadrontherapy, near Pavia) is in its final step of construction and is about to be fully operative. It is based on a synchrotron that can accelerate protons up to 250MeV and carbon ions up to 400MeV/u for the treatment of patients. In this paper we describe an A/D interface, used in the power supply control system of the synchrotron main dipoles, called B-Train. The field is measured in a dedicated dipole connected in series with the sixteen ones of the synchrotron and is then fed back to the power supply. The field is obtained integrating and digitizing the voltage induced on a pickup coil inserted in the gap of the seventeenth dipole. The A/D interface under study is based on a 64-channel current to frequency converter ASIC, in CMOS 0.35 μm technology, followed by a counter and uses a recycling integrator technique. The digital signal obtained is then used to generate a feedback signal for control system of the dipoles power supply. We present the electronic structure, the lab measurements and the behavior for various setups of the A/D interface described. | ||
| THPP121 | The SSRF Storage Ring Dipole and Sextupole Magnet Power Supplies | 3641 |
|
||
| SSRF is a third generation synchrotron radiation light source. It has a full energy injection storage ring of 3.5GeV. The storage ring dipole magnet string and sextupole magnets strings are powered by 10 large magnet power supplies. The power supply output current ranges from 250A to 800A, and the output voltage ranges from 140V to 840V. These power supplies are digital controlled, with bridge topology, and diode rectifiers with step-down transformers. In this paper, the commissioning results of these power supplies are presented, together with the circuit topology and the control schemes. | ||
| THPP122 | Fast High-Power Power Supply for Scanning Magnets of CNAO Accelerator | 3643 |
|
||
| The paper presents the design aspects and performance measurements of the CNAO Scanning Magnets’ power supply (PS) rated ±550A/±660V and developed in collaboration between OCEM SpA and INFN-CNAO. CNAO is a medical synchrotron producing carbon ions and protons for the cure of deep tumours. The Scanning Magnets are dipole magnets used to move the beam in an x-y plane at the very end of the beam extraction line. The PS current will be set in order to cover the targeted tumour area. To accomplish such a task the specifications of the PS are very stringent: current ramp speed is required to be as fast as 100 kA/s with an overall precision class of 100 ppm. Moreover the wide (20x20 cm2) area to be covered by the beam requires a wide current range. High voltage peaks are required during transients whereas low voltage is needed during steady state. The above characteristics are challenging design issues both with respect to topology and control optimization. | ||
| THPP123 | Ramping Power Supplies for the SSRF Booster | 3646 |
|
||
| The SSRF booster magnetic field ramped with a 250ms ramp, 2Hz cycle rate, and biased quasi-sinusoidal wave shape is successfully realized. Two Digital Switch-mode Power Supplies (DSPS) separately deliver currents to all dipoles, and other four DSPS deliver to the quadrupoles and sextupoles in families. Tracking precision and reducing line power fluctuation requirements are particularly challenging because of the fast ramp and high inductance load. In order to meet the requirements, the magnetic energy recycle, digital regulation and novel PID correction circuit are used. On Oct. 5th 2007, after a few days commissioning of the SSRF booster, the beam was boosted up to 3.5GeV firstly in SSRF, it proved that the design of ramping power supplies was correct and the manufacture was successful. The power supply system and its performance are described in this paper. | ||
| THPP124 | Commissioning of the 150 MeV SSRF Linac | 3649 |
|
||
| The 150 MeV SSRF linac has been integrated and commissioned from late 2006 to middle of 2007. This paper presents the design, installation, commissioning and status of this linac. | ||
| THPP125 | Performance Evaluation of the Switching Mode AC Power Supply | 3652 |
|
||
| In order to improve the injection efficiency, the output current waveform of the AC power supplies must be great. Therefore, to ensure smooth and efficient injection of the booster ring, the phase jitter of the AC power supplies current must be less than ±4ns. A new AC power supply is constructed and employ IGBT modules operating at higher switching frequency than the old GTO-based system for the dipole magnet. This new power supply will not only improve the phase jitter but also increase the operating efficiency than the old power supply. The measured dynamic range of the of the 10 Hz sine wave current output is better than 75dB and phase jitter is less than ±4ns. The improved performance evaluation is illustrated in the paper. | ||
| THPP126 | Four Quadrant 60 A, 8 V Power Converters for LHC | 3655 |
|
||
| The LHC (Large Hadron Collider) particle accelerator requires many true bipolar power converters (752), located under the accelerator dipole magnets in a radioactive environment. A special design and topology is required to obtain the necessary performance while meeting the criteria of radiation tolerance and compact size. This paper describes the ±60A ±8V power converter, designed by CERN to meet these requirements. Design aspects, performances and test results of this converter are presented. | ||
| THPP127 | ATF2 High Availability Power Supplies | 3658 |
|
||
| ATF2 is an accelerator test facility modeled after the final focus beamline envisioned for the ILC. By the end of 2008, KEK plans to commission the ATF2. SLAC and OCEM collaborated on the design of 38 power systems for beamline magnets. The systems range in output power from 1.5 kW to 6 kW. Since high availability is essential for the success of the ILC, Collaborators employed an N+1 modular approach, allowing for redundancy and the use of a single power module rating. This approach increases the availability of the power systems. Common power modules reduces inventory and eases maintenance. Current stability requirements are as tight as 10 ppm. A novel, SLAC-designed 20-bit Ethernet Power Supply Controller provides the required precision current regulation. In this paper, Collaborators present the power system design, the expected reliability, fault immunity features, and the methods for satisfying the control and monitoring challenges. Presented are test results and the status of the power systems. | ||
| THPP128 | Failure Mechanisms of Power Systems in Particle Accelerator Environments and Strategies for Prevention | 3661 |
|
||
| This paper discusses the mechanisms that cause degradation and failure in DC-DC converters destined for high radiation and magnetic field environments, particularly those encountered in accelerators. Failure mechanisms discussed include transformer saturation, loss of PWM control, and power supply turn-off. Degradation mechanisms that produce circuit performance outages include circuit parameter drift in Mosfets due to temperature and Vgsth reduction. Environmentally induced drift of current limit, voltage references, and switching performance are also presented. The author’s background in worst case analysis of Space based power supplies gives them particular insight into the radiation impact, assessment, and mitigation of such phenomenon. A variety of techniques for identifying and reducing the probability of these failures are presented. Methods include analysis based strategies, modified switching timing and control, improved gate drive circuitry, proper component selection, and appropriate shielding. Results are provided for a 3kW supply developed for the LHC at CERN using COTS in an 45kRAD TID, 7.7·1012 neutron fluence, and 300 Gauss magnetic field environment. | ||
| THPP129 | New Generation of AD-measurement Cards for High Accuracy Measurements | 3664 |
|
||
| Current transducers, together with the AD conversion of the measured current, are the key elements of high precision power supplies. The accuracy of commercially available current transducers is within the range of a few ppm. Any degradation of this precision by the succeeding stages must be kept as small as possible. Therefore, the accuracy of the AD conversion has to be at least in the same order of magnitude. The presented AD-measurement card improves the accuracy of the available, already calibrated precise ADCs by correcting the remaining errors. The necessary accuracy can only be achieved by measuring and correcting the miscellaneous errors of ADC and involved components, like voltage reference, antialiasing filter and input amplifier. From the measured deviation a correction look-up table is derived and later processed. Other implemented means for the improvement of the precision are the stabilization of the temperature, minimization of the electromagnetic influence by galvanic isolation, reduction of electrical noise and a fully differential signal path. | ||
| THPP130 | SSRF Magnet Power Supply System | 3667 |
|
||
| The Shanghai Synchrotron Radiation Facility (SSRF) is a third-generation synchrotron radiation light source. In SSRF, there are 520 sets of magnet power supplies for the storage ring and 163 sets for injector. All of the power supplies are in PWM switched mode with IGBT. A high precision stable output power supply for 40 dipoles rated at 840A/800V with the stability of ±2·10-5/8hrs is used for the storage ring. 200 sets of chopper type power supplies are used for exciting main winding of quadrupoles independently. In the booster, two sets of dynamic power supplies for dipoles and two sets for quadrupoles run at the biased 2Hz quasi-sinusoidal wave. All above power supplies work with digital power supply controllers designed by either PSI or SINAP. All power supplies are manufactured at professional power supply companies in China. | ||
| THPP132 | Review of the Initial Phases of the LHC Power Converter Commissioning | 3670 |
|
||
| The LHC requires more than 1700 power converter systems that supply between 60A and 12kA of precisely regulated current to the superconducting magnets. For the first time at CERN these converters have been installed underground in close proximity to many other accelerator systems. In addition to the power converters themselves, many utilities such as air and water cooling, electrical power, communication networks and magnet safety systems needed to be installed and commissioned as a single system. Due to the complexity of installing and commissioning such a large infrastructure, with inevitable interaction between the different systems, a three phase test strategy was developed. The first phase comprised the manufacture, integration and reception tests of all converter sub-systems necessary for powering. The second phase covered the commissioning of all the power converters installed in their final environment with the utilities. The third phase will add the superconducting magnets and will not be covered by this paper. The planning and execution that have led to the successful completion of these initial phases are described. Results and conclusions of the testing are presented. | ||
| THPP133 | Magnet Power Converters for the New Elettra Full Energy Injector | 3673 |
|
||
| A large number of power converters has been required to supply the coils and the magnets of the four sub-structures of the new Elettra full energy injector. The Linac, and the two transfer lines require highly stabilized DC power converters while the Booster has to be operated at 3 Hz supplying the magnets with sinusoidal current waveforms. The extraction Bumpers require slow pulse supplies. In order to keep all output voltages below 1 kV, a special connection has been adopted for the Booster dipoles. A particular type of low power four-quadrant converters with embedded Ethernet connection has been designed at Elettra for this specific project. The article will present the relevant facts about the different power converters and their performances. | ||
| THPP134 | Injection and Extraction DC Magnets Power Supplies for 3GeV Rapid Cycling Synchrotron of J-PARC | 3676 |
|
||
|
Proton beams have been successfully accelerated to the design energy of 3 GeV in the RCS at the J-PARC*. In the injection, dump and extraction sections of the RCS, septum magnets, a quadrupole magnet, dc kicker magnets and steering magnets have been installed and operated at DC. For the septum magnets, there is little space area available for the septum coil and a magnetic shield**. Therefore the power supplies are required high excitation current. Maximum currents of the injection and dump septum magnets are less than 7 kA. The extraction septum magnets need the maximum current of 12 kA***. For saving the cost and the installation space of the extraction septum magnets power supplies, a main power supply, which excites three extraction septum magnets in series, and three auxiliary power supplies for adjusting the current to the each magnet are employed. Long-term stability and the current ripples are required to be less than the order of 100 ppm for those power supplies in order to provide the required acceptance for the beams. This presentation shows design and measurements of the the injection and extraction DC power supplies.
*JAERI Technical Report 2003-044 and KEK Report 2002-13. |
||
| THPP136 | The Replacement of the Isis White-circuit Choke | 3679 |
|
||
|
ISIS, located at the Rutherford Appleton Laboratory is the world’s leading pulsed neutron source. It produces intense bursts of neutrons every 20mS when 800MeV protons are fired into a heavy metal target by an accelerating synchrotron. The ISIS synchrotron is based on a resonant “White Circuit”* allowing superimposed DC and AC currents to circulate in the ring of dipole and quadrupole magnets. The magnets themselves resonate with tuned capacitor banks at 50Hz and a large ten-winding choke allows both a path for the DC component of the current and a means to inject the AC power which maintains the 50Hz AC oscillation. This choke, which dates from the 1960’s, was a veteran of the “NINA” synchrotron in Daresbury before it began service at ISIS. Should it fail it could take at years to repair and a scheme is now well under way to replace it with ten individual chokes with in-situ spares so that the system will gain redundancy and robustness. This paper covers progress to date and the problems that have been encountered and their solutions.
*M. G. White et al. "A 3-BeV High Intensity Proton Synchrotron," The Princeton-Pennsylvania Accelerator, CERN Symp.1956 Proc., p525. |