JASRI/SPring-8, Hyogo-ken
KEK, Ibaraki
MHI, Tokyo
Mitsubishi Heavy Industries Ltd. (MHI), Takasago
We have been developing a system to generate a short pulse X-ray using crab cavities at SPring-8 Storage Ring. The ring holds 30-m long straight sections and the vertical beam size at the center of the straight sections is 6.5 micrometers in standard deviation. If we install four superconducting crab cavities and a mini-pole undulator in one of the straight sections, we can convert the time distribution of the electron bunch into the spatial distribution. After slicing the emitted photons with vertical slits, we can obtain a sub-picosecond X-ray pulse. In this scheme, the maximum repetition rate of the short pulse X-ray is the same as the acceleration frequency of the ring (508MHz) and user experiments at other beam-lines are not disturbed by this short pulse generation. We are planning to install KEKB type crab cavities as vertical deflectors. Phase fluctuation among crab cavities must be reduced less than 14 mdeg in order to avoid residual deflection in the vertical direction. In this paper, we report an overview of the short pulse generation scheme and topics of hardware development for stabilization of the RF phase fluctuation.
NIRS, Chiba-shi
Construction of new treatment facility as an extension of the existing HIMAC facility, in which all treatment room will be equipped with a 3D pencil beam scanning system, is in progress at NIRS. The challenge of this project is to realize treatment of a moving target by scanning irradiation, because pencil beam scanning is more sensitive to organ motions compared with the conventional broad-beam irradiation. To accomplish practical moving target irradiation, a prototype of the scanning irradiation system was constructed and installed into existing HIMAC physics experiment course. One of the most important features of the system to be tested is fast scanning toward moving target irradiation with a relatively large number of rescannings within an acceptable irradiation time. Commissioning of the prototype is successfully in progress cooperating with highly stabilized beam provided by the HIMAC accelerator complex. We will report the design of the system and the status of the beam study.
CLS, Saskatoon, Saskatchewan
Storage rings require corrector magnets for a variety of tasks. Foremost are small dipole magnets for both horizontal and vertical correction. In light sources, for example, other corrector magnets are needed to compensate for the effect of changing insertion device operation points. These can include quadrupole, skew quadrupole, sextupole and skew sextupole corrections. As well octupole magnets may be desirable to improve dynamic aperture in small emittance lattices. One magnet can perform all these tasks. This is achieved by having separate windings with separate power supplies on an octopole yoke. The simultaneous excitation of any combination of modes can be achieved through superposition. Corrections are necessarily limited to avoid saturation effects that will degrade the superposition.
KEK, Ibaraki
The KEKB is a high luminosity accelerator which achieved the highest luminosity record of 2.1x1034. It requires the precise and stable beam control to keep its high luminosity continually. Slight change of the magnetic field may easily deteriorate the performance of the collisions of the very small and thin beams. The field measurement accuracy better than 10-4 has been already achieved. The resolution of the measurement has reached to a few 10-5. But it is known by the beam studies that the field change less than 10-4 may cause deterioration of the luminosity. The requirement on the stability of magnetic field will be stricter for future nano beam colliders. We have studied the effects of the following conditions on the magnetic field by using some KEKB magnets: changes of the magnetic field due to air or cooling water temperature, changes due to initialization conditions, field coupling between the adjacent magnets, effect of excitation of the adjacent magnet and behavior of the magnetic field under polarity change have been measured. These studies are not only useful for the existing KEKB but also important for future nano beam accelerators.
KEK, Ibaraki
MELCO SC, Tsukuba
J-PARC, KEK & JAEA, Ibaraki-ken
Efforts have been made to reduce the magnetic field ripple of the bending, quadrupole and sextupole magnets of the J-PARC main ring using the trim coils of the magnets. The quadrupole magnet has 24 turn main coil and 11 turn trim coil per pole those can be considered as a primary winding and a secondary winding of a transformer. When the trim coil is shorted, the induced trim coil current cancels the field ripple. The field ripple of the quadrupole magnet was reduced by a factor of 6 by shorting trim coil. The trim coil current, however, deforms the acceleration field pattern if the coil is shorted all the time of the current pattern of flat bottom, acceleration, flat top and recovery. The MOSFET relay was used to short the coil and to reduce the field ripple during the flat bottom and flat top. The circuits were built for the quadrupole and sextupole magnets. The plan has been made to wind optimized trim coils for the bending magnets.
Muons, Inc, Batavia
North Carolina State University, Raleigh, North Carolina
Magnet applications for high energy physics has long been an important driver for the development of superconducting technology. New high temperature superconductors (HTS), which have very high values of the upper critical field Hc2, show promise for magnets generating fields greater than 25 T, such as those required for muon cooling [1]. (Rare Earth)Ba2Cu3Oy (REBCO) coated conductor is an HTS material which is well suited to these needs; however it requires characterization in the low temperature (4.2 K), high magnetic field regime. We are proposing to measure electro-mechanical and magnetic properties, including angular field dependence of commercially available REBCO conductor. Here we present results of initial testing to characterize commercially available REBCO coated conductors at 77 K, including critical current and quench testing to calculate minimum the quench energy (MQE) and normal zone propagation velocity (NZPV).
Danfysik A/S, Jyllinge
Danfysik A/S has developed a novel approach in constructing a low voltage, very high current and highly stable magnet power supply using parallel SCR converter stages. The design is well suited for driving superconducting magnets in a two quadrant operation. A ±10V 18kA power supply has been built to EPFL Lausanne with four parallel converters showing excellent performances and a very low installation time. One of the major difficulties in paralleling SCR converters is the current sharing between the individual converters, which becomes even harder at low voltages. The novel design, which will be presented here, assures current sharing within a few percent in the whole working area. The power supply has been developed having the following highlights in mind: High accuracy and stability (50ppm.), Good current sharing between parallel coupled converters without band width degradation, Very high current, One or two quadrant operation and Computer controlled. This paper describes the power converter topology ensuring the excellent current sharing.
HUST, Wuhan
High voltage electron accelerators are currently utilized in various industrial applications for Crosslinking Compounds, Sterilization, Polymerization, and vulcanization etc. The conceptual design of a high voltage electron accelerator for radiation technologies is considered in the paper. The key components of the electron accelerator are introduced and analyzed. Relevant physical parameters of the accelerator are then obtained. In order to verify the rationality of the design, beam optical paths are calculated by TRANSPORT program. The beam envelopes show that the physical design of this system can meet the requirement of engineering.
KEK, Ibaraki
The J-PARC accelerator complex consists of a linear accelerator (330 m long, 181 MeV), a rapid cycling synchrotron (3 GeV RCS, 350 m circumference, 25 Hz) and a slow cycling synchrotron (MR, 30 GeV as a first step energy, 1600 m circumference, typically with 3.5 sec cycle). The RCS provides high intensity proton beam to the materials and life science facility and the MR. The MR has two beam extraction lines. One is a slow extraction system for the hadron physics, and other a fast extraction system for neutrino science. We have to challenge many issues to complete construction of the J-PARC accelerator facility on-schedule in 2008 despite all the hardships, such as the problems included in the original design, technology choices and fabrication procedure of the machine components, and construction of conventional facilities. As a first step of operation, we could commission all accelerator facilities and provide beam to all experimental facilities in 2009 successfully. We will report about analysis of these issues and how to solve them, which is a necessary step to realize the design beam power as a next step, and to challenge the future upgrade beyond the original design.
CERN, Geneva
Fermilab, Batavia
Two events, occurring in 2008 during commissioning of the LHC circuits, lead to fundamental changes to the scope of circuit protection. The discovery of aperture-symmetric quenches and the accidental rupture at 9kA of an interconnecting busbar resulted in an emergency program for development and implementation of new protection facilities. The new scheme comprises a distributed busbar supervision system with early warning capabilities based on high-precision splice resistance measurements and system interlocks for rapid de-excitation of the circuit in case of a sudden splice resistance increase. The developed symmetric quench detectors are digital systems with radiation-resistant FPGA logic controllers, having magnet heater firing capabilities. This program successfully allowed a safe re-powering of the collider. The concept of the new electronics boards and the powering modules will be described. More than 14'600 extra cables and 6'000 new detector and control cards were added to the existing QPS system. A first evaluation of the system performance as well as a number of interesting discoveries made during the commissioning will be presented.
ORNL, Oak Ridge, Tennessee
The chopper system for the Spallation Neutron Source (SNS) provides a gap in the beam for clean extraction from the accumulator ring. It consists of a pre-chopper in the low energy beam transport and a faster chopper in the medium energy beam transport (MEBT). It took several iterations to develop a working design with the required parameters. In this paper we describe the latest design of the MEBT chopper deflector and give results of the experimental verification of the chopper effectiveness, the gap cleanness and the rise time measured with high resolution using the SNS laser wire. The effect on the losses will be discussed as well.
IHEP Beijing, Beijing
To monitor the beam profile at the end of linac non-destructively, Wire scanner as a new diagnostic instrument was designed, manufactured and installed in 2007. After that, we had done beam test for several times using this device. This paper describes the whole system of wire scanner and beam test result.
NSRRC, Hsinchu
To keep and achieve desired performance of a modern synchrotron light source, it requires continuous efforts including good design of the accelerator, good performed subsystems and sophisticated feedback system. While some wonders happen unexpectedly and could deteriorate performance of the light source. For examples, some strong source occasionally occurred especially after long shut down or malfunction of some corrector power supply and it would result in increased noise level. Non ideal injection element will cause large perturbation as well. This report presents algorithms to spatially locate source and summarize some of our practical experience to identify the source.
KEK, Ibaraki
Hitachi Haramachi Electronics Co. Ltd., Hitachishi, Ibaraki
KFG, NEUSS
Kikusui Chemical Industries Co. Ltd, Kagamihara Shiga
KYOCERA Corporation, Higashiomi-city, Shiga
Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga
New beam abort system designed for KEKB upgrade, consists of horizontal and vertical kicker magnets, pulsed quadrupole magnets, a Lambertoson septum magnet and a beam dump. Water-cooling ceramic chambers are used for the kicker and pulsed quadrupole magnets. At the KEKB upgrade project, the beam abort gap is required to be less than 200 nsec. The beam currents are increased and their emittance is supposed to be much smaller than KEKB. In order to avoid melting the extraction Ti window, the pulsed quadrupole magnets will be installed. They enlarge the beam cross section at the extract window. The components for the SuperKEKB abort system are developed. The compact water-cooling ceramic chambers are developed to reduce the gap of kicker magnets and bore radius of the pulsed quadrupole magnets. The power supply for the kicker magnet is also developed to satisfy the 200 nsec rise time requirement.
NIRS, Chiba-shi
AEC, Chiba
Toshiba Medical Systems Corporation, Tochigi
In the routine operation of HIMAC synchrotron, a pulse system of field change with 0.2 Gauss in the monitor dipole magnet (B-clock) is used to generate pattern data in the acceleration system. To eliminate error pulse due to noise in analogue field signal, a clock system locked to a 1.2kHz clock for a power supplies was developed, which can be used to generate pattern data of an acceleration system with maximum frequency of 192kHz. This 1.2kHz clock is synchronized to a power line frequency of 50Hz that will fluctuate about 0.1%, so the clock of 192kHz must also follow this frequency fluctuation. To demonstrate the performance of new clock system, we have tested beam acceleration, and compared with the conventional B-clock system. Acceleration efficiencies were checked with changing these clock rates in the both systems. With these tests, we have found that the relatively low clock rate in the newly developed system is enough to get good acceleration performance. In this paper the clock system, and their beam tests will be presented.
INFN-Pisa, Pisa
University of Pisa and INFN, Pisa
Superconductive cavities for future linear accelerators, such as ILC, have extremely large quality factors requiring an effective stabilization with both slow and fast tuners. Piezoelectric actuators are the most common choice for fast tuners, but one drawback for a large scale application is the limited bandwidth and the large cost of commercially available drivers. In this paper we present a low cost driver which is ideally suited for fast tuner application, large system packaging and has an excellent flexibility in its implementation. Driving piezoelectric actuators having capacitive loads up to a few microfarads in the kHz range requires amplifiers with good current output capabilities at a few hundred volts. The Piezo Control Unit we developed for the ILC Test Area at Fermilab is composed by a 6U Eurocard crate hosting 5 Piezo Driver modules capable of driving up to 10 piezoelectric actuators. Main specifications include large voltage rails (-175 V to +175V), wide signal bandwidth (DC to10 kHz) and low output noise ( <10 mVrms). The driver is equipped with both output voltage and output current monitor.
KEK, Ibaraki
A new set of magnets, skew sextupole magnets, were designed, manufactured, measured and installed during the winter shutdown of 2009. Twenty magnets were installed in the HER and eight magnets were installed in the LER. It was a challenging job for the magnet group to design, manufacture, measure the magnetic field and install them in the tunnel in just three months. Much effort to finish the installation in time and reduce the production cost was made at every step of the entire process. With these newly installed skew sextupole magnets, a significant luminosity boost was achieved. The production and installation of the skew sextupole magnets are described in this report.
NSRRC, Hsinchu
National Tsing-Hua University, Hsinchu
The test results of a dual one-turn coils configuration for Taiwan Light Source (TLS) booster extraction kicker is presented in this report. The achieved capability of the test unit demonstrates that the rise-time of the kicker current pulse has been improved for beam extraction optimization. This improved performance is mainly accomplished by reducing the load inductance effectively with a dual one-turn coils configuration. The measured result of rise-time variation versus the corresponding load inductance change is briefly discussed.
ASCo, Clayton, Victoria
The Australian Synchrotron has been open to users since April 2007. Beam availability is now consistently above 98%, with a Mean Time Between Failures (MTBF) of approximately 50 hours and a Mean Down Time (MDT) of approximately 1 hour. This paper discusses the program of activities that has been undertaken to improve beam availability, and to maximize the MTBF and reduce the MDT.
JASRI/SPring-8, Hyogo-ken
SES, Hyogo-pref.
RIKEN/SPring-8, Hyogo
In top-up operation at SPring-8 the horizontal beam oscillation had been excited because the injection bump orbit is not closed perfectly. For this problem, we had made an effort to reduce the residual beam oscillation by the improvement of bump magnet design, reducing the effect due to the nonlinearity of sextupole magnet and introducing pulsed corrector magnet, etc. By these improvements the average amplitude of residual oscillation has now been suppressed to the level of less than 0.1 mm. Still remaining relatively large residual oscillation comes from a non-similarity of a temporal shape of magnetic field of four bump magnets. We then started development fast kicker magnet system to give a counter kick to this part of residual beam oscillation. A key technology in this development is how to generate a large pulsed current in a short period to meet the oscillation characteristic. A newly developed fast pulsed power supply can generate a current of about 300 A, or corresponding magnetic field of 4.61 mT, with a pulse width of 1.2 us. Recently, we succeeded in the reduction of the horizontal beam oscillation at the timing of firing bump magnets by using this kicker system.
KEK, Ibaraki
KEK manages two synchrotron radiation sources, Photon Factory storage ring (PF-ring) of 2.5 GeV and Photon Factory advanced ring (PF-AR) of 6.5 GeV. These rings share an injector linac with the two main rings of KEK B-factory, 8-GeV HER and 3.5-GeV LER. Recently, the linac has succeeded in a pulse by pulse multi-energy acceleration. A top-up operation of PF-ring has been realized as the simultaneous continuous injection to the 3 rings, PF-ring, HER and LER. Development of new injection scheme using a pulsed sextupole magnet continues aiming at practical use in the top-up operation. A rapid-polarization-switching device consisting of tandem two APPLE-II type undulators has been developed at PF-ring. The first undulator was installed in 2008, and the second one will be installed in 2010 summer. PF-AR, operated in a single-bunch mode at all times, has been suffered from sudden lifetime drop phenomena attributed to dust trapping for many years. Using the movable electrodes installed for experiment, we confirmed that the discharge created by the electrode was followed by the dust trapping, and succeeded in a visual observation of luminous dust streaking in front of CCD cameras.
KEK, Ibaraki
Most of the magnet power supplies of the KEKB rings and beam transport lines are connected to the local control computers through ARCNET. For this purpose we have developed the Power Supply Interface Controller Module (PSICM), which is designed to be plugged into the power supply. It has a 16-bit microprocessor, ARCNET interface, trigger pulse input interface, and parallel interface to the power supply. According to the upgrade plan of the KEKB accelerators, more power supplies are expected to be installed. Although the PSICMs have worked without serious problem for 11 years, it seems too hard to keep maintenance for the next decade because some of the parts have been discontinued. Thus we decided to develop the next generation of the PSICM. Its major change is the use of the Ethernet instead of the ARCNET. On the other hand the specifications of the interface to the power supply are not changed at all. The new PSICM is named ePSICM (Ethernet-based Power Supply Interface Controller Module). The design of the ePSICM and the development of the prototype modules are in progress.
SINAP, Shanghai
SSRF control system is a hierarchical standard accelerator control system based on EPICS. The VME 64X system, special embedded controller and PLCs are used for low level devices control or interlocks system. Using a uniform 1000Base-T backbone redundancy control network instead of field bus for mostly device controller with VLAN technique adopted, and integrate with EPICS using soft IOC. Digital technology such as digital power supply control system, new event timing system and digital phase control system are used and also integrated with some embedded EPICS IOC. An uniform System development and run time environment of hardware and software is adopted at the whole process. The high level physical application environment using MatLab 2007a with Accelerator Toolbox (AT) & middle layer with MatLab CA (Channel Access) connected component MCA/LabCA. The high level physical application can be integrated with the control system easily and conveniently. With the SSRF centre database, an enhanced distributed archive engine based on RDBS with native XML data type is been testing.
NSRRC, Hsinchu
Modbus-TCP is a widely used in industry for a long time and accelerator control system recently. Modbus protocol over Ethernet has advantages for non real-time applications due to its maturity. The TPS (Taiwan Photon Source) project will have many Modbus-TCP enable devices which distributed in utility system and accelerator system. The accelerator control environment of TPS project is an EPICS toolkit based system. Modbus-TCP might adopt for some subsystems. There are several possible Modbus-TCP devices including the prototype power supply for magnet field mapping application equip with Modbus-TCP interface, vacuum system local controller, front-end controller, and some monitoring devices. In this paper, we will summarise preparation efforts to accommodate the Modbus-TCP support in the TPS control system.
NSRRC, Hsinchu
Implementation of the Control system for the Taiwan Photon Source (TPS) is on going. The TPS control system will provide versatile environments for machine commissioning, operation, and to do accelerator experiments. The control system is based on EPICS toolkits. Test-bed has set up for various developments. The open architecture will facilitate machine upgrade, modification easily and minimize efforts for machine maintenance. Performance and reliability of the control system will be guaranteed from the design phase. Development status will be summary in this report.
NSRRC, Hsinchu
In order to help early development of TPS control system and user interface, a virtual accelerator model is constructed. The virtual accelerator has been created by AT toolbox and simulated beam behavior; the Middle Layer providing high level accelerator application is also used. LabCA interfaces between Matlab and EPICS (Experimental Physics and Industrial Control System). Such a system could speed development of commissioning required software and examine the correction of all procedures.
NSRRC, Hsinchu
KEK, Ibaraki
The EPICS embedded programmable logic controller (PLC) has been developed based on F3RP61-2L, a CPU module of a FA-M3R series PLC running Linux OS. The EPICS IOC resided in F3RP61-2L module can access the registers of sequence CPU modules and I/O modules of the PLC. The embedded EPICS PLC was applied to control the prototype of pulse magnet power supply and support functionality testing remotely. The system comprises various input/output modules and a CPU module with built-in Ethernet interface. The control information (status of the power supply, ON, OFF, warn up, reset, read/write voltage, etc.) can be accessed remotely using EPICS client tools. The EDM is selected to develop the GUI for itself. Efforts are summarized in this report.
CLASSE, Ithaca, New York
BNL, Upton, Long Island, New York
Commissioning of the high brightness photoinjector for the Energy Recovery Linac at Cornell University continues. To aid in this process we have developed a 'Virtual Accelerator' application, which provides the beam physicist with an online high-level physics description of the machine. This application combines a linear optics model called Numerical Transfer Matrix (NTMAT), developed at Cornell, and EPICS-DDS, a middle-layer software based on the Experimental Physics and Industrial Control System (EPICS) toolkit and the Data Distribution Service (DDS) data-centric publish/subscribe model. We present the initial results of implementing this new software tool and its deployment in the Cornell ERL injector control room.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
In view of increased processing bandwidth at demanding experiments and the need for rapid compensation of noise spikes and new, yet unknown excitations a fast orbit feedback aiming at noise suppression in the 1Hz-50Hz range has become mandatory for the 3rd generation light source BESSY II. As a first step the fast setpoint transmission plus the replacement of all corrector power supplies is foreseen. Later - in combination with top-up operation - orbit stability can be further improved by replacing today's multiplexed analog beam position monitors by parallel processing fast digital units. This paper describes how the pilot installation of a small subset of fast corrector power supplies already allows to tune performance and study the benefits for today's most sensible experiments.
NSRRC, Hsinchu
As the latest generation light source, TPS (Taiwan Photon Source) has stringent requirements to perform submicron beam stability with low emittance. The slow and fast correctors of integrated orbit feedback system have been designed for TPS project, therefore some feedback system designed based on them an operation experiences from TLS. This report will present performance simulation and the initial design of system infrastructure for large scale calculation and wide bandwidth communication. To perform this requirement, FPGA-based platform will be implemented to achieve low latency and fast computation. Some studies of integrated feedback loop, communication structure, devices control such as BPM electronics and corrector power supplies are also described.
CERN, Geneva
A complex Machine Protection System has been designed to protect the LHC machine from an accidental release of the beam energy, with about 20 subsystems providing status information to the Beam Interlock System (BIS). Only if the subsystems are in the correct state for beam operation, the BIS receives a status flag and beam can be injected into LHC. The BIS also relays commands from the connected subsystems in case of failure for emergency extraction of beam to the LHC Beam Dump Block. To maintain the required level of safety of the BIS, the performance of the key components is verified before every fill of the machine and validated after every emergency beam dump before beam operation is allowed to continue. This includes all critical paths, starting from the inputs from connected system triggering a beam dump request, followed by the correct interruption and propagation sequence of the two redundant beam permit loops until the final extraction of the beam via the LHC beam dumping system. In this paper we report about the experience with the BIS that has been deployed for some years in the SPS (as LHC injector), in the transfer lines between SPS and LHC and recently in LHC.
INFN/LNF, Frascati (Roma)
CNAO Foundation, Milan
CNAO, the Italian Centre of Oncological Hadrontherapy located in Pavia, is under commissioning and will be soon fully operational. It is based on a synchrotron that can accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV for the treatment of patients. In this paper we present the subsystem, called B-Train, which has the purpose of measuring the magnetic field in a dedicated dipole connected in series with the sixteen dipoles of the synchrotron and to provide instantaneous values of the synchrotron field to the dipole power supply, to the RF, diagnostics and dump bumpers control systems, via optical lines, using a custom communication protocol. In order to measure the magnetic field with the specified precision (0.1G over 1.5T @ 3 T/s), a different approach has been taken with respect to previous versions of the system. The field is obtained by digitizing the voltage induced on a pick-up coil inserted in the gap of the dedicated dipole through a 18 bit, 1.25 Msamples/s ADC and integrating it by numerical methods. This paper describes the final design and features of the B-Train system, as well as the results obtained on the magnetic field readings precision.
Karlsruhe Institute of Technology (KIT), Karlsruhe
BNG, Würzburg
One of the advantages of superconducting insertion devices (IDs) with respect to permanent magnet IDs is the possibility to enlarge the spectral range by changing the period length by reversing the direction of the current in a part of the windings. In this contribution we report the first experimental test of this principle demonstrated on a 70mm NbTi mock-up coil with period tripling, allowing to switch between a 15mm period length undulator and a 45mm wiggler.
JASRI/SPring-8, Hyogo-ken
RIKEN/SPring-8, Hyogo
Low electro-magnetic noise interference (EMI) is required to the klystron modulator power supply for XFEL/SPring-8 project in order to realize the highly stable beam operation with aid of various feedback loops using high-performance beam monitors. The dominant noise source is the thyratron switching noise, associated with its rapid voltage swing of 50 kV maximum. To suppress the noise leakage, special care was taken to the enclosure design of klystron modulator, i.e., using thick steel plates a monocoque enclosure was fabricated, in which all of the high power circuits was installed. The rapid image current flows on the inner surface, thus EMI was minimized. A special co-axial feed-though was developed for filtering the conducted noise on power line for thyratron and klystron heaters. In this presentation, we will report the details of the devices and the results of the noise suppression.
KEK, Ibaraki
At PF-AR, a bending magnet power supply was updated in 2007. The converter works in the 3 pulsed PWM. A trouble caused by higher harmonics above 40th had occurred. We manufactured filters and installed in 6.6kV ac lines in 2008. Furthermore, a QF magnet power supply was updated in 2009. This paper reports on the update of PF-AR main magnet power supplies.
KEK, Ibaraki
Osaka University, Graduate School of Engineering, Osaka
RLNR, Tokyo
Magnets of the synchrotron accelerator which extracts the accelerated beams are excited by pulse operation power supply, and then the load fluctuation should be a severe problem. An energy storage system, such as SMES, fly-wheel generator so far, will be required for compensating the pulse electric power, and reducing the disturbances of the connected power line. The system is also expected to protect the instantaneous voltage drop and contributes the reliability of the storage ring. Present status of R & D and the features for the energy storage systems are discussed. The application of the energy storage systems to synchrotrons for the medical use is described. The compensation of the typical pulse electric power of the synchrotron for the cancer therapy is studied.
KEK, Ibaraki
J-PARC, KEK & JAEA, Ibaraki-ken
The power supply current ripple of the quadrupole magnets of the J-PARC main ring has been measured to be the order of 10-4. The magnetic field of the quadrupole magnets has been measured and the ripple frequency distribution of each magnet was observed to be depending on where the magnet is in the magnet chain. A transmission line model for the cable and magnets was able to explain the distribution. The field ripple made by the common mode current ripple was reduced by changing the magnet cabling to be symmetrical with respect to the N and S poles of the quadrupole magnets. The common mode ripple was drastically reduced. The normal mode ripple of 600, 1200 and 1800 Hz however remained. The field ripple was further reduced using resistors those are connected in parallel to the magnet coils and bypass the current ripple. It was effective to the higher frequency ripple of 1200 and 1800 Hz and the effect was in a good agreement with an electric circuit simulation program LTspice.
JAEA, Ibaraki-ken
In J-PARC RCS, horizontal closed orbit distortion (COD) which is ±2 or 3mm in amplitude was observed all over the ring. Main component of the horizontal COD is 1kHz, phase variation period about 140 seconds. This paper demonstrates phase variation of the 1kHz horizontal COD caused by switching ripple from dipole magnet power supply. To suppress the phase variation of the horizontal COD, switching timing of the dipole magnet power supply was synchronized J-PARC timing system.
RCNP, Osaka
The ordinary electric circuits produce and receive electromagnetic noise. The noise is a problem for stable operation of synchrotron accelerators. We do not know the origin of the noise generation due to the lack of electric circuit theory, which takes into account the noise sources. The proper treatment of electric circuit together with noise requires a proper knowledge of multiconductor transmission-line theory. We have developed a new multiconductor transmission-line theory in which we are able to describe the performance of multiconductor transmission-line system*. In this theory, it is essential to use the coefficients of potential instead of capacities and the introduction of the normal and common modes. After understanding the multiconductor transmission-line theory, we propose the introduction of the middle line (three lines) and symmetric arrangements of electric loads**. The use of this concept made the J-PARC MR successful in operation.
* H. Toki and K. Sato, J. Phys. Soc. Jpn 78 (2009) 094201.
** K. Sato and H. Toki, Nucl. Inst. Methods A565 (2006) 351.
PAL, Pohang, Kyungbuk
Lattice of the Storage Ring (SR) is changed from TDB to DBA, and beam energy is enhanced from 2.5 GeV to 3.0 GeV at the Pohang Light Source upgrade (PLS-II). Therefore all magnet specification and number have to change compare with exist PLS SR. At the PLS-II, Magnet Power Supplies (MPS) must be re-designed according to magnet specification of the PLS-II. Newly development MPSs are adopted switching type power conversion technology. High current unipolar MPSs are parallel operation type of unit module buck type power supply, and low current bipolar MPSs are H-bridge type. All MPSs are performed ± 10 ppm output current stability and adopted full digital controller. In this paper, we report on the development and characteristics of the MPS for PLS-II SR.
PSI, Villigen
In accelerator applications, high precision high speed power supplies (PSs) for magnets are needed to guarantee the high beam quality. These PSs are the main purpose of the presented second generation of a Digital Power Electronic Control System (DPC) which has been designed and successfully applied at the Paul Scherrer Institute PSI. The main components of the DPC are the controller board (DPC_CC) and the high precision analogue to digital converter board (DPC_AD). Compared to the first generation the properties such as precision, acquisition rate, processing power and functionality have been improved considerably. This allows faster control cycles and/or more complex control algorithms. The controller board now features 12 standard precision (16 bit) ADC channels and allows the simultaneous control of multiple power supplies. High precision requirements are met by adding the DPC_AD to the system. In conclusion, the modular and flexible design allows well-matched solutions for the typically heterogeneous accelerator power supplies.
NSRRC, Hsinchu
The purpose of this paper is to estimate the conductive Electromagnetic Interference (EMI) from magnet power supply in NSRRC. A LISN system was conducted to measure the EMI spectrum of power supply. The different frequency range of conductive EMI was measured. For the future TPS(Taiwan Photon Source) power supply design, the EMI signals must be lower than TLS kicker. Therefore reducing and eliminating the interference of electromagnetic waves will be a very important issue. A filter and shielding method were used to test the effects of reducing EMI. The EMI prevention scheme will be used in the future.
NSRRC, Hsinchu
We design and implement a power convert to supply dc power bus for the MCOR30 correction supply. The dc power supply's characteristics were variable frequency at heavy and medium/light load. These characteristics matched with the correction supply working requirement. The dc power bus has a relaxation oscillator generating a symmetrical triangular waveform, which MOSFET's switching is locked to. The frequency of this waveform is related to a current that will be modulated by feedback circuitry. As a result, the tank circuit driven by half-bridge will be stimulated at a frequency dictated by the feedback loop to keep the output voltage regulated, thus exploiting its frequency-dependent transfer characteristics. The high performance characteristics of the resonant dc power bus are illustrated in this paper.
NSRRC, Hsinchu
The Taiwan Photon Source (TPS), a third-generation synchrotron radiation light source, should be installed with 1032 sets of magnet power supplies for the storage ring and 152 sets for the injector. All of the power supplies are preferred in PWM switched mode with IGBT or MOSFET. A high precision DC power supply for 48 dipoles of the storage ring; there are 240 quadrupole magnets and 168 sextupole magnets in storage ring, the main winding of quadrupole and 168 sextupole magnets are powered by individual power supplies. In the booster ring, one set of dynamic power supply for the dipole magnets and four sets for quadrupole magnets run at the biased 3Hz quasi sinusoidal wave. There are several hundred corrector (fast and slow) magnets and skew quadrupole magnets in storage ring and injector are powered by the same bipolar power converters.
NSRRC, Hsinchu
This paper presents an implementation of a precision corrector magnet power converter using the digitally controlled pulse width modulation method. The output current precision of this ±10A/±50V corrector magnet power converter is within ±10ppm. The digital control circuit of the power converter is implemented with using a high speed ADS8382 18-bits analog-to-digital converter and a TMS320F28335 digital signal processor. The converter uses a full bridge configuration, the switching frequency of power MOSFET is 40 kHz and the control resolution is 17-bits. Using a DCCT as the current feedback component the output current ripple of this converter could be lower than 5 ppm that is beyond the requirement of TLS corrector power converter and suitable to be used in TPS.
ANL, Argonne
The DC/DC converters in the Advanced Photon Source storage ring are more than 15 years old, and an upgrade is underway to resolve the aging and obsolescence issues. In the upgrade, an 18-bit resolution for current regulation is desired. This paper describes a digital control system to achieve this goal. The system uses a serializer chip, TI TLK2541, combined with a ∑-Δ modulator to realize a 21-bit digital pulse width modulation (DPWM). Analog and digital filters are implemented to block the ripple currents and to reduce the EMI noises. Deployed with filter circuits, a digital compensator has been designed to meet the requirements of output current regulation. Furthermore, a voltage feed forward is employed to compensate for input bus voltage variations. A prototype digital controller using a field-programmable-gate-array development board has been developed. The resolution of the current regulation, and the effect of noises into the digital controlled power converter system have been tested and analyzed.
RIKEN/SPring-8, Hyogo
XFEL/SPring-8 will use 72 line type modulator pulse-power supply for 66 C-band klystrons, 4 S-band, one L-band and pulsed 500 kV electron gun. In order to make the size smaller to fit the space available in the high gradient C-band accelerator, we have developed all in one box design of modulator. Using metal monocok design, filled with oil, it becomes possible to fit all circuitry: PFN, thyratron, pulse transformer, klyston socket, and protection circuit into a metal box of W 1m x L 1.7m x H 1m, which provides strong support for massive klystron and solenoide with lead shield and functions as superior EM shiled. We developed high precission HV charger for PFN, which has stability better than 100 ppm.pp. Modulator and PFN chargers are under mass prodution.
KEK, Ibaraki
This paper describes a long-pulse 1.3 GHz klystron modulator that was recently developed for the Superconducting RF Test Facility (STF) at High Energy Accelerator Research Organization (KEK). The modulators is a direct-switched-type design with a 1:15 step-up transformer and a bouncer circuit to compensate for the output pulse droop within ±0.5%; it can drive a klystron with up to 10 MW peak power, 1.5 ms rf pulse width, and up to 5 pps repetition rate. The main features of this modulator are the use of four 50 kW switching power supplies in parallel to charge the storage capacitors to 10 kV, self-healing-type capacitor to realize a compact storage capacitor bank, and a highly reliable IGBT switch which enables elimination of a crowbar circuit. Design considerations and its performance are presented. An IEGT (Injection Enhanced Gate Transistor) switch, composed of six series devices with a rating of 4.5 kV and 2100 A-DC, has been also developed and tested for R&D to realize a compact modulator.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
J-PARC, KEK & JAEA, Ibaraki-ken
KEK, Ibaraki
At the J-PARC 3-GeV injection, the injection painting area is designed to be different for supplying the MLF (Material Life Science Facility) and MR (50GeV Main Ring) beams. Along with the injection system in the ring, pulsed switching magnets which are installed in the injection beam-line should also have a function to control the beam orbit at 25Hz. The deflection angle ranges from 3 to 38 mrad to meet the user operation as well as the beam physics run.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
3 GeV rapid cycling synchrotron (RCS) of J-PARC accelerates proton beams from the 181 MeV up to 3 GeV. The RCS injects the beam to the Main Ring and transports it to the muon production target and neutron production target in the Materials and Life Science Experimental Hall. Proton beams in the RCS are fast extracted by kicker magnets at the repetition rate of 25 Hz. The rise time of the magnetic field is approximately 260 ns due to the propagation time through the coaxial cable and the kicker magnet itself. The flat-top length of it is required to 840 ns in order to extract two beam bunches. Pulse forming lines (PFL) and thyratrons are used to make the rise time and the flat-top, at the maximum charging voltage of 80 kV. Two thyratrons, which is a CX1193C made by e2V Ltd., are used for a power supply. 16 thyratrons are used in the eight power supplies of the kicker system. Since thyratrons are gaseous discharge switching devices, they often make misfire or self-breakdown in several hours. In this paper, present status of operation and voltage adjustment method of the reservoir and cathode heater power supply of the thyratrons in the kicker system are described.
NSRRC, Hsinchu
National Tsing-Hua University, Hsinchu
A test unit of a pulse-forming-network (PFN) kicker power supply has been designed and fabricated for Taiwan Photon Source (TPS) beam injection/extraction of the booster ring. In order to fulfill the requirements, the performance of the designed unit has been bench tested and the results are examined for evaluation purpose. The pulse-to-pulse stability and the flattop specifications are specified according to the beam injection/extraction requirements. Effort has been made to enhance the rise/fall time of the delivered pulse current. The engineering evaluation and its possible application for beam diagnostics purpose are briefly discussed.
Diversified Technologies, Inc., Bedford, Massachusetts
Diversified Technologies, Inc. (DTI) recently delivered a 500 kW CW, 33 kV solid-state test stand for the evaluation and conditioning of high power tetrodes employed in accelerator and radar systems. The test system consists of DTI-manufactured and commercially-sourced power supplies, a DTI high voltage opening switch, and DTI controls. Combining an opening switch and fast responding power supplies allows the hi-potting and high power burn-in to be consolidated in one test stand. Faulty tubes, which would not operate in a crowbar-equipped modulator, and could not be processed to health on a high potter, can be revived to health with this fast opening switch circuitry. By limiting peak fault current and follow-on-current, the total energy in an arc event is greatly minimized, reducing damage inside the tube. If greater energy (or action) is required for initial tube processing, additional load capacitance downstream of the switch can be added into the circuit for 'spot knocking' purposes. This test stand is capable of operation in pulsed mode as well as CW. This paper will address the design and construction of the test stand and discuss results since its installation.
Diversified Technologies, Inc., Bedford, Massachusetts
Diversified Technologies, Inc.(DTI) has delivered a fully solid state Klystron Power Supply for the ISIS Front End Test Stand to Rutherford Appleton Laboratory in the UK. The new pulsed power supply drives a Toshiba E3740A klystron in preparation for construction of a system to demonstrate high quality intense chopped beams. DTI's system represents a significant advance in solid-state high power accelerator technology based upon a hard switch developed for the US Department of Energy (DOE) to meet similar requirements for the International Linear Collider(ILC). The system includes two 220 kW switching power supplies, a 110 kV solid state hard switch pulse modulator, mod anode and filament power supplies, klystron fault protection, and interfaces to the ISIS controls. This paper will address the design and construction of the KPS system, as well as test results from the installation at RAL in May 2009.
CERN, Geneva
In the LHC, a large number of superconducting magnets are powered remotely by 5 superconducting links at distances of 70 up to 540 m. This innovation allowed to choose more convenient locations for installing the electrical feedboxes and their related equipment. The consolidations performed after the first commissioning campaign and the operational experience with the superconducting links over a period of several months are presented. Based on the successful application of superconducting links in the LHC, such devices can be envisaged for powering future accelerator magnets. Several possible cryogenic configurations for future superconducting links are presented with their respective figures of merit from the cryogenic and practical implementation point of view.
NIRS, Chiba-shi
The betatron tune fluctuation due to the current ripple of power supplies brings the beam spill ripple through the stable area variation in resonant slow extraction. The effect becomes dominant especially in the case of the low beam rate extraction. The RF-knockout slow extraction method is insensitive to the tune ripple compared to the ordinary one because it uses the diffusion with the transverse RF field. However, the ripple effect appears even in the beam spill extracted by it. The amount of the separatrix fluctuation due to the tune ripple depends on the difference between the bare and the resonant tune, and the sextupole magnetic strength. We measured the correlation between the beam spill and the tune ripple which was the artificially generated with low and high frequency components of 67 Hz and 1167 Hz near those of the real current ripple. We confirmed the reduction of the beam spill ripple by setting the tune away from the resonance while keeping the separatrix area. The comparison between the experimental results, the analytical calculation and the simulation will be reported.
KEK, Ibaraki
J-PARC, KEK & JAEA, Ibaraki-ken
University of Fukui, Faculty of Engineering, Fukui
Tokyo City University, Tokyo
Tsukuba University, Ibaraki
JAEA/J-PARC, Tokai-mura
High power protons from the J-PARC main ring is slowly extracted using the third integer resonance and delivered to the experimental hall for various nuclear and particle physics experiments. The slow extraction device comprises two electro static septa (ESS),ten magnetic septa, four bump magnets, eight resonant sextupole magnets and their power supply. One of the critical issue of the slow extraction is radiation caused by the beam loss during the slow extraction. We have developed the electrostatic and magnetic septa with thin septum thickness. A unique scheme with large step size and small angular spread of the extracted beam enables hit rate on the ESS less than 1% level. In January 2009, first 30 GeV proton beam has been successfully delivered to the fixed target. Quadrupole magnets and a DSP feedback control system to obtain a uniform beam spill structure were implemented in 2009 summer shutdown period. We will report the extraction efficiency, extracted beam profiles and spill structure obtained by the beam commissioning so far. We will also mention a upgrade plan based on some new ideas to aim a higher performance.
LNLS, Campinas
In November 2010, LNLS plans to replace the two 50 kW UHF klystron valves which currently provides power to the RF cavities installed in the storage ring. Thanks to a close collaboration with the Syncrotron Soleil started in 1999, LNLS adapted the characteristics of the French project to 476 MHz. The choice of the transistor, the design of the combiners and details on power supplies will be reported, as well as the power tests performed with the two amplifiers using a resistive load.
DESY, Hamburg
BINP SB RAS, Novosibirsk
For the European XFEL project horizontal multi-beam klystrons will be installed in the XFEL tunnel and will be connected to the double tank pulse transformers. Both, the klystron and pulse transformer need for the normal operation to be filled with oil. To avoid the possible oil leakage during connection of the klystron and transformer tank inside tunnel, the connection module (CM) was proposed. The CM will be mounted on the support platform of the klystron and through the tube socket connected to the guns electrodes outside of the tunnel and will transported to the tunnel together with klystron. The connection to the pulse transformer tank will be done only with HV cable, because the CM has inside it the filament transformer. To reduce the weight and volume of the oil the design of filament transformer was done as high frequency coaxial one with coupling factor of 0.58 and working frequency about 1 kHz. The CM has the built-in current and voltage monitors. In this paper we give an overview about design and test result of the CM together with klystron.
KEK, Ibaraki
ERL (Energy Recovery Linac) of 5GeV energy is a future plan in KEK and in order to study the technical feasibility, construction of a compact ERL machine (cERL) is considered. Beam energy and current of cERL are 245MeV and 100mA, respectively. As 1.3 GHz frequency and super conducting cavity are chosen for the RF system, similar technology with KEK STF is employed. From 2008, KEK started the preparation of cERL and one RF unit of injector linac is introduced in this fiscal 2009. A new cw klystron of 300kW out put power, 150kW Y-type circulator and high power water load were developed in FY2009. DC power supply was under manufacturing. Preliminary test of HLRF and the high power couplers are scheduled in the Photon Factory site by making use of the old DC power supply. For main accelerator, we also introduced a 30kW IOT and a 35kW klystron and a DC power supply. At the same time, cERL is determined to be constructed in the East Counter Hall in KEK and the design layout is preceded. In this paper, the recent RF source development of cERL is described. Layout of the east counter hall, where cERL is constructed, is progressed and shown in this report.
CERN, Geneva
SLAC, Menlo Park, California
CEA, Gif-sur-Yvette
IAP/RAS, Nizhny Novgorod
The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for CLIC accelerating structure testing. A design and fabrication contract for five klystrons at that frequency has been signed by different parties with SLAC. France (CEA Saclay) is contributing a solid state modulator purchased in industry to the CLIC study. RF pulses over 120 MW peak at 230 ns length will be obtained by using a novel SLED I type pulse compression scheme designed and fabricated in Nizhny Novgorod, Russia. The X-band power test stand has been installed in the CLIC Test Facility CTF3 for independent structure and component testing in a bunker, but allowing, in a later stage, for powering RF components in the CTF3 beam lines. The design of the facility, results from commissioning of the RF power source and the performance of the Test Facility are reported.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
The Muon Ionisation Cooling Experiment (MICE) is being constructed at Rutherford Appleton Laboratory in the UK. A muon beam will be cooled through a process of absorption using hydrogen absorbers and acceleration using 200MHz copper RF cavities. This paper describes the RF power source used to accelerate the muon beam, testing of the high voltage power supplies and amplifiers to date and progress on the RF distribution scheme to the accelerating cavities.
CPI, Beverley, Massachusetts
The VIL409 Heatwave IOT-based RF amplifier was designed to meet the requirements of the EMMA accelerator at the Daresbury Laboratory. The VIL409 was successfully commissioned in September 2009. The VIL409 provides up to 90 kW RF output power ver a 5.5 MHz bandwidth centered at 1.3 GHz. It operates at a fixed 1.6 millisecond pulse at up to 20 Hz. Within limits, the user has control of the IOT beam voltage and the IOT grid bias voltage. Normal operation is to achieve smooth control of the output via the LLRF input alone. The IOT grid may be pulsed or operated at a constant voltage; pulsing achieves greatly enhanced energy efficiency. The VIL409 has an embedded processor that controls all internal functions of the amplifier system and interfaces directly to the EPICS control system. The embedded controller provides real-time pulse data to EPICS and operates slow-moving interlocks. Safety and IOT-protective interlocks are hard-wire circuits which operate in the microsecond timeframe. The VIL409 can be operated locally or controlled remotely on the EPICS controls network. This paper describes the VIL409 high power RF amplifier system.
LANL, Los Alamos, New Mexico
Compa Industries, Inc., Los Alamos, New Mexico
An major upgrade is replacing much of the 40 year-old proton drift tube linac RF system with new components at Los Alamos Neutron Science Center (LANSCE). When installed for the LANSCE-R project, the new system will reduce the total number of electron power tubes from twenty-four to eight in the RF powerplant. A new 200 MHz high power cavity amplifier has been developed at LANSCE. This 3.2 MW final power amplifier (FPA) uses a Thales TH628 Diacrode, a state-of-the-art tetrode that eliminates the large anode modulator of the triode-based FPA that has been in use for four decades. Drive power for the FPA is provided by a new tetrode intermediate power amplifier and a solid-state driver stage. The new system has sufficient duty-factor capability to allow LANSCE to return to 1 MW beam operation. Prototype RF power amplifiers have been designed, fabricated, and assembled and are being tested. High voltage DC power became available through innovative re-engineering of an installed system. Details of the electrical and mechanical design of the FPA and ancillary systems are discussed. Power test results have validated the design and construction of this very high power amplifier system.
JLAB, Newport News, Virginia
Cockcroft Institute, Lancaster University, Lancaster
The use of an injection locked CW magnetron to drive a 2.45 GHz superconducting RF cavity has been successfully demonstrated. With a locking power less than -27 dB with respect to the output and with a phase control system acting on the locking signal, cavity phase was accurately controlled for hours at a time without loss of lock whilst suppressing microphonics. The phase control accuracy achieved was 0.8o r.m.s. The main contributing disturbance limiting ultimate phase control was power supply ripple from the low specification switch mode power supply used for the experiment.
NSRRC, Hsinchu
The electric power system of Taiwan Photon Source (TPS) will be installed during the construction of TPS. Many power electronic devices which produce large nonlinear loads will be used in the new power system and the accelerator facility. The capacitor banks will also be used for the power factor correction. Thus, the excessive harmonic waveform distortion level on the normal waveform will be presented continuously. These excessive harmonic current flows will result in transformer and cable over-heating and many types of circuit faults, and also wasting energy. A project is initiated to study these harmonic effects which will appear in the electric power system of TPS. A computer simulation approach is used to study the harmonic waveform distortion phenomena, and also to investigate an effective approach to reduce it. The harmonic effects of selected section of TLS (Taiwan Light Source) electric power system, and those appear at the mock segment of 1/24 accelerator of TPS system are measured and compared with the simulated results.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The Front End Test Stand (FETS) under construction at the Rutherford Appleton Laboratory is the UK's contribution to research into the next generation of High Power Proton Accelerators (HPPAs). Running at duty cycles of up 50 Hz with pulse lengths of 2 ms are required. This paper presents initial Hminus beam currents and emittance measurements for long pulse lengths.
IKP, Mainz
Siemens AG, Erlangen
The university of Mainz institute for nuclear physics is operating the microtron cascade MAMI (Mainzer Mikrotron) since the late 1970ies. The microtron delivers a cw electron beam to users of the hadron physics community. The recent, fourth stage MAMI-C having a design energy of 1.5 GeV is operated since 2006*. This article deals with the recent developments and operational experiences of MAMI-C, as well as with the energy upgardes to 1.56 GeV** and as final step towards 1.6 GeV. The final increase of beam energy was due to user demands, since it is expected to raise the event rate of the eta prime production by an order of magnitude.
* A.Jankowiak, et al., EPAC08, Genoa, Italy, p.51 (MOZCM01)
** A. Jankowiak, et al., PAC09, Vancouver, Canada (WE6PFP111)
BNL, Upton, Long Island, New York
In this article, based on the contributions of the chromatic sextupole families to the half-integer resonance driving terms, we discuss how to sort the chromatic sextupoles in the arcs of the Relativistic Heavy Ion Collider (RHIC) to easily and effectively correct the second order chromaticities. We propose an online method with 4 knobs or 4 pairs of chromatic sextupole families to correct second order chromaticities. Numerical simulations support this method and shows that it improves the balance of correction strengths among the sextupole families and avoids reversal of sextupole polarities, as well as yielding larger dynamic apertures for the 2009 RHIC 100 GeV polarized proton run.