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| MPPE066 | Streak Camera Studies of Vertical Synchro-Betatron-Coupled Electron Beam Motion in the APS Storage Ring | electron, synchrotron, betatron, storage-ring | 3694 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. W-31-109-ENG-38. |
We present experimental studies of synchro-betatron-coupled electron beam motion in the Advanced Photon Source storage ring. We used a vertical kicker to start the beam motion. When the vertical chromaticity is nonzero, electrons with different initial synchrotron phases have slightly different betatron frequencies from the synchronous particle, resulting in a dramatic progression of bunch-shape distortion. Depending on the chromaticity and the time following the kick, images ranging from a simple vertical tilt in the bunch to more complicated twists and bends are seen with a visible light streak camera. Turn-by-turn beam position monitor data were taken as well. We found that the experimental observations are well described by the synchro-betatron-coupled equations of motion. We are investigating the potential of using the tilted bunch to generate picosecond x-ray pulses. Also note that the fast increase in vertical beam size after the kick is dominated by the internal synchro-betatron-coupled motion of the electron bunch. Experimentally this increase could be easily confused with decoherence of vertical motion if the bunch is only imaged head-on. |
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| MPPP001 | A Vertical Multi-Bunch Feedback System for ANKA | feedback, storage-ring, synchrotron, injection | 761 | ||
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ANKA is a synchrotron light source with a top energy of 2.5 GeV. The maximum electron current at ANKA is presently limited by multi-bunch instabilities to 200 mA. In order to overcome this barrier a transverse analog multi-bunch feedback system is presently being commissioned. A BPM is used for beam detection. The vertical position signal passes a notch filter, is amplified, and subsequently fed to a vertical beam kicker. The present paper shows the layout of ANKA feedback system and discusses the first results of its operation.
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| MPPP002 | Stochastic Cooling Electrodes for a Wide Velocity Range in the CR | impedance, pick-up, coupling, antiproton | 799 | ||
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The CR storage ring is part of the FAIR project at GSI. It serves as a first stage of stochastic cooling for secondary rare isotopes at v/c=0.83 as well as for antiprotons at v/c=0.97. To avoid the installation of dedicated structures for each kind of beam, electrodes have been developed which are usable for both beams. They are based on slotline structures mounted perpendicular to the beam. They are shorted at the ends, and their signal is extracted by two striplines on the rear side, placed a quarter wavelength away from the open ends. The width of the structures can be adjusted to the initial betatron oscillation amplitudes. Their length is 24 mm, and the signal from many of these structures mounted in a row can be combined. The signal combination can be matched to the different beam velocities. The paper shows results from field calculations, prototype tests, and estimates of the signal combination efficiency. The beam impedance of the novel structures is compared with the superelectrodes applied in the former CERN AC and with the slow-wave structures currently installed in the FNAL Debuncher.
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| MPPP005 | A New Kicker for the TLS Longitudinal Feedback System | impedance, coupling, storage-ring, feedback | 949 | ||
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A new longitudinal kicker that is modified from the Swiss Light Source (SLS) design to fit into the TLS storage ring. It will be served as the actuator in the longitudinal multi-bunch feedback control loop. Beam coupling impedance has been calculated by Gdfidl with a PC cluster. Previous to the installation of this new kicker, bench measurement has been performed in the laboratory to characterize this new kicker. The experimental setups for bandwidth and coaxial wire measurement of longitudinal coupling impedance and their corresponding test results will be reported. As a cross check, bead-pull measurement has also been done to verify the beam coupling measurement by coaxial wire method at the kicker center frequency. Longitudinal field profile of the accelerating mode along the beam path has also been mapped. High order cavity modes of the kicker have also been observed and their effects on the beam are evaluated.
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| MPPP011 | Fermilab Recycler Damper Requirements and Design | impedance, betatron, damping, feedback | 1239 | ||
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The design of transverse dampers for the Fermilab Recycler storage ring is described. An observed instability and analysis of subsequent measurements are used to identify the requirements. The digital approach being mplemented is presented.
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| MPPP023 | Numerical Calculation of Coupling Impedances for Kicker Modules | impedance, coupling, simulation, extraction | 1820 | ||
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Funding: Work supported in part by DFG under contract GraKo 410 and GSI, Darmstadt. |
Maintaining the impedance budget is an important task in the planning of any new accelerator facility. While estimates from analytical computations and measurements play a central role in doing so, numerical calculations have become an important alternative today. On the basis of Finite Integration Theory, we have developed a simulation tool for the direct computation of coupling impedances in the frequency domain. After discussing the special features of our code as compared to commercial programs, we present our results for cases where coupling impedances have been obtained from another source, e.g. experiment. In particular, we consider the longitudinal and transverse impedances of the SNS extraction kicker and present investigations related to the injection/extraction system of the future heavy-ion synchrotron at GSI. |
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| MPPP052 | Longitudinal Impedance Measurements of the Components for the BEPCII | impedance, storage-ring, vacuum, injection | 3212 | ||
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Funding: Work supported by the National Natural Science Foundation of China (NSFC) under contract No.10375076. |
A longitudinal impedance measurement system was established for the BEPCII. The measurements, done in the frequency domain, are based on the coaxial wire method using HP/Agilent 8720ES network analyzer. The applications of the TRL calibration technique and absorbers were investigated to find a good approach for impedance measurements. The impedance, larger than 20 Ohm and below 6 GHz, can be measured using the TRL calibration technique in the experiment. And better measurement results were got using the reference pipes with the absorbers. So, this system satisfies the requirements of the BEPCII. This paper gives a review on this impedance measurements system for the BEPCII. The measurements results show that there are no serious impedance problems for BEPCII bellows and injection kickers, agreeing well with the numerical simulations. More improvements on this system are in progress. |
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| MPPT005 | A New Slotted-Pipe Kicker Magnet for BEPCII Storage Ring | impedance, vacuum, injection, storage-ring | 955 | ||
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The requirements of BEPCII injecting kicker magnets are so severe. In the range of ?x=±20mm, the field uniformity is required to be better than ±1% in the central plane, ±2% in the y=5mm plane and ±5% in y=10mm plane, while the effective beam impedance of each kicker magnet must be lower than 0.025O. For the large aperture of vacuum chamber and the fast risetime of kicker magnetic field, the two schemes of low impedance kicker magnets used in other accelerator labs in the world are not adaptive to the BEPCII storage ring. A new slotted-pipe kicker magnet, which uses the ceramic bars with metal coating films as the image current conducting paths, proposed in this article solves the difficult problems of BEPCII kicker magnet design. And the successful construction of a prototype has demonstrated that the new scheme of kicker magnets is viable and the structure design of the kicker magnet is reasonable.
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| MPPT006 | The Extraction Kicker System of the RCS in J-PARC | vacuum, extraction, impedance, proton | 1009 | ||
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The kicker magnet plays a role of extracting the proton beam which is accelerated up to 3GeV by the Rapid Cycling Synchrotron in J-PARC. The kicker system is required the fast rise time of the magnetic field because the interval between the beam bunches is only 349nsec. The kicker magnet is the distributed type. The findings in our measurements revealed that the delay time in the magnet is about 180nsec. The power supply has the pulse forming network system, which consists of co-axial cables whose characteristic impedance is 10 ohm. We accomplished the current rise time of 80 nsec quickness. Therefore we had a good prospect of the fast rise time of the magnetic field. The characteristic impedance of the kicker magnet was also measured. The value was close to 10 ohm. There will be no large mismatching between the power supply and the magnet. This pulse magnet is installed in the vacuum chamber to prevent the electric discharge. Outgas from the components has the adverse effects the vacuum in the accelerator. We have reduced the outgas rate from the ferrite core and aluminum plates which construct the magnet by backing them at appropriate temperature.
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| MPPT014 | Design Concept for AGS Injection Kicker Upgrade to 2 GeV | proton, injection, impedance, simulation | 1380 | ||
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Funding: Canada Foundation for Innovation, U.S. Dept of Energy. |
The present AGS injection kickers at A5 location were designed for 1.5 GeV proton injection. Recent high intensity runs have pushed the transfer kinetic energy to 1.94 GeV, but with an imperfect matching in transverse phase space. Space charge forces result in both fast and slow beam size growth and beam loss as the size exceeds the AGS aperture. A proposed increase in the AGS injection energy to 2 GeV with adequate kick strength would greatly reduce the beam losses making it possible to increase the intensity from 70 TP (70 * 1012 protons/s) to 100 TP. R&D studies are being undertaken by TRIUMF, in collaboration with BNL, to design two new kicker magnets for the AGS A10 location to provide an additional kick of 1.5 mrad to 2 GeV protons. TRIUMF has proposed a design for a 12.5 W transmission line kicker magnet with rise and fall times of 100 ns, 3% to 97% and field uniformity of ±3% over 90% of the aperture, powered by matched 12.5 W pulse-forming lines. This paper describes the present status of a prototype design including the results of detailed 2D and 3D electromagnetic modeling of a transmission line kicker magnet and PSpice time domain analysis of the magnetic kick strength. |
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| MPPT016 | Beam Injection for the PF-AR with a Single Pulsed Quadrupole Magnet | injection, quadrupole, dipole, emittance | 1517 | ||
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We develop the injection system for PF-AR (Photon Factory Advanced Ring for Pulsed X-ray) with single pulse quadrupole (PQ) magnet without pulse local bump of the stored beam with four dipole kickers. The pulse quadrupole magnet has the length of 30cm, the field gradient of 3T/m, half-sine-form pulse width of 2.4mSec, measured inductance of 1.8mH and the peak current of about 2000A. With this magnet, the amplitude of the injected beam can be reduced to about the half of that only with septum magnets and the reduced amplitude is almost the same as the case of the usual injection with the pulse bump of the stored beam. We installed PQ-magnet at the short straight section near the south symmetric point of PF-AR in this summer of 2004 and succeeded to inject beam to the storage ring during the machine study in autumn, 2004.
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| MPPT020 | Magnetic Field Measurement on a Refined Kicker | injection, radiation, storage-ring, synchrotron | 1682 | ||
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To prepare for the operation of top-up mode and increase the efficiency of injection at storage ring, National Synchrotron Radiation Research Center (NSRRC) has upgraded the kicker magnets and power supply. We have built up a new magnetic field measurement system to test the kicker. This system, including a search coil and a coil loop, can map the field and take the first integral of field automatically. We also simulate the trajectory of electron beam by pulsed wire method of field measurement. We analyze the performance of the kicker system in this paper.
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| MPPT055 | The LANSCE Switchyard Kicker Project | diagnostics, vacuum, injection, power-supply | 3310 | ||
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Until 2003, the existing configuration of the LANSCE switchyard did not allow simultaneous delivery of the H- beam to Lines D and X. In the late 1990’s, with increased activities in Areas B and C, which serve the ultracold neutron experiments (UCN) and proton radiography (PRad), respectively, planning began to increase beam availability to all areas by installing a kicker system, dubbed the "Switchyard Kicker." The Switchyard Kicker is a system of two pulsed and two direct current magnets that enables simultaneous, uninterrupted beam delivery to Line D for the Lujan Center and the Weapons Neutron Research (WNR) Facility and, on request, a tailored H- beam pulse to Line X for the pRad and UCN research areas. The project received funding in July 2001 for design and implementation. During the 2003 Extended Maintenance Period this upgrade was installed in the Switchyard and commissioned during the Accelerator Turn-On period in the summer of 2003. With the commissioning successful, LANSCE now routinely operates in "Kick" mode, delivering simultaneous beam to Line X and Line D, increasing beam availability to all areas and simplifying production scheduling.
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| MPPT070 | Construction and Power Test of the Extraction Kicker Magnet for the Spallation Neutron Source Accumulator Ring | extraction, vacuum, SNS, power-supply | 3831 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
Two extraction kicker magnet assemblies that contain seven individual pulsed magnet modules each will kick the proton beam vertically out of the SNS accumulator ring into the aperture of the extraction lambertson septum magnet. The proton beam then travels to the 1.4 MW SNS target assembly. The 14 kicker magnets and major components of the kicker assembly have been fabricated in BNL. The inner surfaces of the kicker magnets were coated with TiN to reduce the secondary electron yield. All 14 PFN power supplies have been built, tested and delivered to ORNL. Before final installation, a partial assembly of the kicker system with three kicker magnets was assembled to test the functions of each critical component in the system. In this paper we report the progress of the construction of the kicker components, the TiN coating of the magnets, the installation procedure of the magnets and the full power test of the kicker with the PFN power supply. |
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| MPPT085 | Fast Magnets for the NSLS-II Injection | injection, septum, electron, storage-ring | 4165 | ||
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Funding: Under Contract with the U.S. Department of Energy Contract Number DE-AC02-98CH10886. |
Third generation light sources require top-off operation in order to provide proper stability of the photon beam. In this paper we present the conceptual design of the fast pulsed magnets used for injection into the 3 GeV storage ring. |
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| TOAC003 | Stochastic Cooling for Bunched Beams | ion, synchrotron, pick-up, heavy-ion | 310 | ||
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Funding: Work performed under the auspices of the U.S. DOE. |
A longitudinal stochastic cooling system for RHIC is under construction and partial commissioning is planned for the upcoming run. The state of the system and future plans are discussed. |
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| TOAA007 | SNS Injection and Extraction Devices | injection, septum, proton, extraction | 553 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The Spallation Neutron Source (SNS) is a second generation pulsed neutron source (1.5 MW) and is presently in the sixth year of a seven-year construction cycle at Oak Ridge National Laboratory. The operation of the facility will begin in 2006. The most stringent requirement for the SNS accelerator complex is to allow hands-on maintenance. Operational experiences show that the most losses occur in the injection and extraction. SNS accumulator ring injection and extraction has been design with grate care to reduce uncontrolled losses. Injection systems consist of fast programmable kicker magnets and DC dump magnets to paint the beam in transverse phase space. Extraction systems consist of fast kicker magnets and a Lamberton magnet to extract beam in single turn. Paper will discuss design, construction and testing of these devices. |
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| TPAP010 | Reliability Analysis of the LHC Beam Dumping System | diagnostics, dumping, extraction, collider | 1201 | ||
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The design of the LHC Beam Dumping System is aimed at ensuring a safe beam extraction and deposition under all circumstances. The system adopts redundancy and continuous surveillance for most of its parts. Extensive diagnostics after each beam dumping action will be performed to reduce the risk of a faulty operation at the subsequent dump trigger. Calculations of the system’s safety and availability are presented, considering the detailed design of the trigger generation system and the power converters of the beam dumping kickers and septa magnets.
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| TPAP033 | Tevatron Admittance Measurement | emittance, proton, antiproton, betatron | 2306 | ||
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Funding: Work supported by the Universities Research Assos., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy. |
We measured the Tevatron Beam Acceptance by the method of exciting the beam emittance growth with the beam tickling system with noise. The noise power was about 3Watt with 100Hz bandwidth and centered either in horizontal betatron frequency or vertical betatron frequency. We were able to blow the beam emittance fast while under control. From the point the beam emittance stop growing, we measured the beam acceptance of the Tevatron. |
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| TPAP035 | Energy Deposition Issues at 8 GeV H- Beam Collimation and Injection to the Fermilab Main Injector | injection, proton, collimation, quadrupole | 2372 | ||
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The energy deposition and radiation issues at 8 GeV H- beam collimation in the beam transfer line and at stripping injection to the Fermilab Main Injector are analyzed. Detailed calculations with the STRUCT and MARS15 codes are performed on heating of collimators, stripping foils and other critical components, as well as on beam line and accelerator element radioactivation both at normal operation and accidental beam loss. Extraction of the unstripped part of the beam to the external beam dump and loss of the excited-state Ho atoms in the Main Injector are also studied.
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| TPAT086 | Enhanced Optical Cooling of Particle Beams in Storage Rings | undulator, pick-up, betatron, radiation | 4179 | ||
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In this scheme undulators are installed in straight sections of a storage ring at distances determined by a phase advance 2pπ+π between first and second undulators and 2π between next undulators, where p=1,2,3.. . UR emitted in the first undulator pass through an optical system with movable screens 1,2 in the image plane of the particle beam. If screens let pass the UR then the past UR is amplified and pass through the second and next undulators together with the particle. Every particle loses its energy in the overlapped fields of the amplified UR and these undulators. Motion of screens in the optical system leads to particle energy losses in second and following undulators similar to losses in moving targets T1,2 in the schemes of enhanced ion cooling.* Energy losses are accompanied by a decrease of both energy spread and amplitudes of betatron oscillations that is enhanced cooling if, at first, the moving screen 2 will produce conditions of the energy loss for higher energy particles. When the screen 2 will open image of all particles the system must be closed and then the cooling process can be repeated*.
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*physics/0404142. |
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| TPPE048 | The Injection System of SAGA Light Source | injection, septum, storage-ring, linac | 3007 | ||
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Saga light Source is a 1.4-GeV electron storage ring with a circumference of 75.6m. The injector is a 250-MeV linac producing 1 ms macro-pulse with a peak current of 12mA and repetition rate of 1Hz. The output beam from the linac is transported though a transport line, and injected into the ring though a septum magnet with a bending angle of 20-degree. The transport line consists of two bending magnets, two quadrupole doublelets, and a quadrupole singlet. The bump orbit is formed by four kicker magnets, two of which are installed at both sides of septum magnet, and other two are positioned apart by one magnet cell of the ring. They are excited by sinusoidal electric currents with a half width of 0.5 ms. The beam optics for the injection trajectory is computed and shown at control room, the parameters for which are provided directly from the power supply control server PC. The operator is able to see real-time result of the beam trajectory calculation. This tool is quite effective to optimize the magnets parameter setting. The commissioning of the light source was started in August 2004, and 250-MeV electrons ware stored first time on November 2004.
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| WPAE058 | High Voltage Measurements on Nine PFNs for the LHC Injection Kicker Systems | injection, simulation, collider, power-supply | 3402 | ||
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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. |
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| WPAE079 | Dual Power Supplies for PEP-II Injection Kickers | injection, power-supply, luminosity, background | 4045 | ||
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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. |
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| WOAB009 | Design, Development, Construction and Installation of a Ceramic Chamber for a Pulsed Kicker at the LNLS Storage Ring | vacuum, synchrotron, booster, storage-ring | 689 | ||
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Funding: MCT - ABTLuS/LNLS. |
Following the upgrade of the LNLS injector system with the addition of a 500 MeV booster synchrotron,the storage ring in-vacuum ferrite injection kicker magnets started to show overheating due the interaction with high frequency electromagnetic fields induced by the electron beam. In this paper, we describe the design of a new ceramic chamber for the kickers which minimize this effect by decreasing the coupling impedance of the kickers and their interaction with the electron beam. |
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| WOAC010 | Measurement of Linear Lattice Functions in the ESRF Storage Ring Using Turn-by-Turn Data | optics, storage-ring, synchrotron, damping | 698 | ||
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A model-independent method to measure linear optics functions has been tested in turn-by-turn data from the ESRF storage ring. This method does not necessitate neither the knowledge of the model nor magnetic element manipulation. It uses only the positions measured in consecutive BPMs of betatron oscillations issued by small transverse kicks. The phase advances and tunes necessary to construct the transfer matrices are issued by refined Fourier analysis. The method's precision is compared with classical methods such as response matrix analysis and beam matrix construction.
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| RPAE042 | Optimization of Kicker Pulse Bump by Using a SR Monitor at the Photon Factory | injection, sextupole, photon, factory | 2717 | ||
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We plan to operate the Photon Factory storage ring by top-up injection mode from 2006. To realize this operation mode, remaining coherent oscillation of the stored beam due to error in the injection pulse bump is one of most serious problem. To reducing the error in the injection pulse bump, we calibrated kicking angles of the injection kicker magnets by means of the term by term instantaneous observation of beam profile. We have a SR monitor inside of injection pulse bump. By measureing the tern by tern beam position after the excitation of kicker magnet, we can calibrate the kick angle of the kicker magnet. By using this calibration, we optimized injection pulse bump. As a result, we reduced amplitude of remaining coherent oscillation less than 1/4 of the 1??of the beam size.
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| RPAE049 | Revision of Booster to Storage Ring Transport Line Design and Injection Scheme for Top-Up Operation at NSRRC | injection, booster, quadrupole, extraction | 3085 | ||
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In order to help the operation of constant current, the optics of booster to storage ring transport line (BTS) design is reinvestigated. The initial twiss parameters are derived by measurement. The optics of the transport line is readjusted according to the measured initial beam parameters. The design of pulse width of the injection kicker is also changed from 1.2μsecond to 2.0μsecond. The injection scheme is reviewed and the effects of the kicker error on both injected beam and stored beam are investigated and shown in this report.
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| RPAE080 | Diagnostic Systems Plan for the Advanced Light Source Top-Off Upgrade | injection, betatron, diagnostics, monitoring | 4066 | ||
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Funding: This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Materials Science Division, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
The Advanced Light Source (ALS) will soon be upgraded to enable top-off operation,* in which electrons are quasi-continuously injected to produce constant stored beam current. We will upgrade our injector from 1.5GeV to full-energy 1.9GeV, and top-off operation will also require more precise injector beam characterization and control than we are capable of using our current diagnostics system. Therefore, a diagnostics upgrade will be crucial for the success of top-off, and our plan for it is described in this paper. Among the improvements will be the integration of all existing beam current monitors along the accelerator chain into an injection efficiency monitoring application. New booster ring diagnostics will include a tune kick and monitoring system, updated beam position monitor electronics, and a new scraper. Two new synchrotron light monitors and a beam stop will be added to the booster-to-storage ring transfer line, and a dedicated bunch purity monitoring system will be installed in the storage ring. Together, these important diagnostic upgrades will enable smooth commissioning of the full energy injector and a quick transition to high quality top-off operation at the ALS. *Please see the ALS Top-off Upgrade presentation at this conference. |
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| RPAT064 | Beam-Based Calibration of the Electron Energy in the Fermilab Electron Cooler | electron, antiproton, dipole, vacuum | 3638 | ||
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Electron cooling of 8.9 GeV antiprotons in the Fermilab’s Recycler ring requires precise matching of electron and antiproton velocities. While the final match can be done by optimization of the cooling process, for the very first cooling one should rely on the knowledge of absolute values of electron and antiproton energies. The upper limit for the energy uncertainty of both beams is determined by the Recycler’s momentum aperture and is equal to 0.3%. The paper discusses a method of the electron energy calibration that is based on the measurement of the electron’s Larmor wavelength in the field of the cooling section solenoid. The method was tested in an 18 m long cooling section prototype with 3.5 MeV electrons. An accuracy of 0.3% was demonstrated.
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| RPAT074 | PEP-II Transverse Feedback Electronics Upgrade | feedback, diagnostics, pick-up, coupling | 3928 | ||
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Funding: Supported by the U.S. Department of Energy under contract No. DE-AC03-76SF00098 (LBNL) and DE-AC03-76SF00515 (SLAC). |
The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx® ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design. |
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| RPAT098 | Phase-Space Dynamic Tracking by a Two Pickups Data Acquisition System | octupole, sextupole, lattice, pick-up | 4326 | ||
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A two pickups dynamic tracking data acquisition system has been developed at LNF for the DAFNE Phi-factory. Two oscilloscopes sample horizontal and vertical sum and difference signals from two pickups simultaneously; the sampling clock is locked to the DAFNE timing system. A horizontal kick excites the beam motion and initiates the acquisition. Turn-by-turn signals are converted to beam position and stored on a server in a database using timestamp labels. Oscillation amplitude versus time, phase space distribution and frequency domain analysis are shown for several lattices and different settings of sextupoles and octupoles. Results are used to check the DAFNE non-linear model.
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| ROAB002 | Advances of Transmission Line Kicker Magnets | injection, impedance, coupling, extraction | 235 | ||
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Fast pulsed magnets or kickers are widely used in circular accelerators for injection, fast extraction and beam excitation. As from the early 60’s transmission line type kicker magnets have been employed to produce rectangular field pulses with good rise time. Over some 40 years this technology has evolved with the rising requirements. Whilst the necessary kick strength has increased with the particle beam energies the strive for efficiency has pushed developments towards lower impedance systems and/or short circuited magnets. The flat top ripple is constrained by the maximally tolerable beam oscillation. The beam intensity can impose a screening of the magnet yoke. The most advanced features implemented in recent transmission line kicker magnets are reviewed and illustrated with examples from different laboratories. Ongoing and potential future developments are briefly discussed.
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| ROAB007 | Pulsed Power Applications in High Intensity Proton Rings | pulsed-power, extraction, impedance, proton | 568 | ||
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Funding: Work performed under the auspices of the U.S. Department of Energy. |
The pulsed power technology has been applied in particle accelerators and storage rings for over four decades. It is most commonly used in injection, extraction, beam manipulation, source, and focusing systems. These systems belong to the class of repetitive pulsed power. In this presentation, we review and discuss the history, present status, and future challenge of pulsed power applications in high intensity proton accelerators and storage rings. |
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| ROAB008 | Solid-State Modulators for RF and Fast Kickers | impedance, induction, power-supply, vacuum | 637 | ||
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Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. |
As the capabilities of solid-state devices increase, these devices are being incorporated into modulator designs for high voltage accelerator applications. Solid-state modulators based on inductive adder circuit topology have demonstrated great versatility with regard to pulse width and pulse repetition rate while maintaining fast pulse rise and fall times. Additionally, these modulators are capable of being scaled to higher output voltage and power levels. An explanation of the basic circuit operation will be presented as well as test data of several different hardware systems. |
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| ROAB009 | NuMI Proton Kicker Extraction System | coupling, extraction, injection, magnet-design | 692 | ||
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Funding: Fermilab is operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the U.S. Department of Energy. |
This system extracts up to 9.6 us of 120 GeV beam every 1.87 seconds for the NuMI beamline neutrino experiments. A pulse forming network consisting of two continuous wound coils and 68 capacitors was designed and built to drive three kicker magnets. The field stability requirement is better than ± 1% with a field rise time of 1.6 us. New kicker magnets were built based on the successful traveling wave magnets built for the Main Injector. Two of these magnets, which have a propagation time of 550 ns, are in series making the risetime of the pulser a serious constraint. A forced cooling system using Fluorinert® was designed for the magnet termination resistors to maintain the field flatness and amplitude stability. The system has been commissioned and early results will be presented. |
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| RPPE016 | Protection Level During Extraction, Transfer and Injection into the LHC | injection, extraction, septum, simulation | 1505 | ||
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Failures during the LHC transfer and injection process cannot be excluded and beam loss with the foreseen intensities and energies, which are an order of magnitude above the damage limit, could cause serious equipment damage. Consequences of equipment failures such as kicker erratics, power converter faults, etc. are investigated by means of a Monte Carlo based on MAD-X tracking with a full aperture model of the transfer line and the injection region. Geometrical and optical mismatch, orbit tolerances, mechanical tolerances for settings of protection elements, power converter ripples, misalignment of elements, etc. are all taken into account. The required performance of the protection system is discussed. The overall protection level for the LHC and the transfer lines during injection is presented.
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| RPPE048 | Physical and Electromagnetic Properties of Customized Coatings for SNS Injection Ceramic Chambers and Extraction Ferrite Kickers | SNS, cathode, vacuum, extraction | 3028 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The inner surfaces of the 248 m SNS accumulator ring vacuum chambers are coated with ~100 nm of titanium nitride (TiN) to reduce the secondary electron yield (SEY) of the chamber walls. All the ring inner surfaces are made of stainless or inconel, except those of the injection and extraction kickers. Ceramic vacuum chambers are used for the 8 injection kickers to avoid shielding of a fast-changing kicker field and to reduce eddy current heating. The internal diameter was coated with Cu to reduce the beam coupling impedance and provide passage for beam image current, and a TiN overlayer to reduce SEY. The ferrite surfaces of the 14 extraction kicker modules were coated with TiN to reduce SEY. Customized masks were used to produce coating strips of 1 cm x 5 cm with 1 to 1.5 mm separation among the strips. The masks maximized the coated area to more than 80%, while minimizing the eddy current effect to the kicker rise time. The coating method, as well as the physical and electromagnetic properties of the coatings for both types of kickers will be summarized, with emphasis on the effect to the beam and the electron cloud buildup. †Corresponding author email: hseuh@bnl.gov. |
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| RPPE049 | Summary on Titanium Nitride Coating of SNS Ring Vacuum Chambers | cathode, extraction, injection, SNS | 3088 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge. |
The inner surfaces of the 248 m Spallation Neutron Source (SNS) accumulator ring vacuum chambers are coated with ~100 nm of titanium nitride (TiN) to reduce the secondary electron yield (SEY) of the chamber walls. There are approximately 100 chambers and kicker modules, some up to 5 m in length and 36 cm in diameter, coated with TiN. The coating is deposited by means of reactive DC magnetron sputtering using a cylindrical magnetron with internal permanent magnets. This cathode configuration generates a deposition rate sufficient to meet the required production schedule and produces stoichiometric films with good adhesion, low SEY and acceptable outgassing. Moreover, the cathode magnet configuration allows for simple changes in length and has been adapted to coat the wide variety of chambers and components contained within the arc, injection, extraction, collimation and RF regions. Chamber types, quantities and the cathode configurations used to coat them are presented herein. A brief summary of the salient coating properties is given including the interdependence of SEY as a function of surface roughness and its effect on outgassing. Limitations of this coating method are also discussed. |
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| RPPP013 | Tests of the FONT3 Linear Collider Intra-Train Beam Feedback System at the ATF | feedback, linear-collider, collider, electron | 1359 | ||
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We report preliminary results of beam tests of the FONT3 Linear Collider intra-train position feedback system prototype at the Accelerator Test Facility at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with a latency below 5 nanoseconds, and a kicker driver amplifier with similar low latency. The 56 nanosecond-long bunchtrain in the ATF extraction line was used to test the prototype with delay-loop feedback operation. The achieved latency represents a demonstration of intra-train feedback on timescales relevant even for the CLIC Linear Collider design.
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| RPPP023 | A Compact Damping Ring Using RF Deflectors for the International Linear Collider | damping, dynamic-aperture, quadrupole, extraction | 1811 | ||
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Funding: NSF |
Current specifications for the International Linear Collider call for bunch trains hundreds of kilometers in length. We describe a scheme for manipulating a compressed bunch train in the damping ring using RF deflectors and multiple transfer lines. The concept is demonstrated in the design of a 4 km damping ring that circulates 2800 bunches spaced 4 ns apart, and we show that injection and extraction of individual bunches is possible with conventional kickers requiring rise/fall times of only 16 ns. The performance and stability of the 4 km damping ring is evaluated and compared with existing machines. |
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| RPPP049 | Bunching for Shorter Damping Rings for the ILC | damping, extraction, linac, positron | 3052 | ||
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A variant rearrangement of the bunch trains for the ILC that enables much shorter damping rings is presented. In a particular example the ~2280 bunches are regrouped into ~450 subtrains of five adjacent bunches. These subtrains are extracted from the damping rings at ~2.2 ms intervals, obtaining the 1ms macrobunch length of the baseline TESLA collider scenario. If the baseline damping rf frequency is 325 MHz and the kicker rise and fall times are ~20 ns, a ring circumference of ~4.5km is required. Variations of the scheme could easily reduce the circumference to ~3km, and faster kickers could reduce it even further.
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| FPAE013 | Calculation of the Orbit Length Change of the Recycler Due to Main Injector Ramp | closed-orbit, dipole, lattice, betatron | 1318 | ||
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Orbit length of beam in the Recycler changes during the Main Injector ramps. The unknown kicks from the effects generated by stray field are distributed around the ring. To estimate the changes, simulated virtual kicks are created around each lambson, C-magnet and bus cable of the Main Injector. The orbit lengths are calculated from measurements of evolution frequency and transverse beam positions. A BPM system distributed throughout the Recycler lattice in both Horizontal and vertical planes are used to take the closed orbit measurement during the ramps. The calculation method and the results of the orbit length changes and the strength of the simulated kicks are presented in this report.
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| FPAE072 | RF-Kicker System for Secondary Beams at NSCL/MSU | secondary-beams, ion, quadrupole, cyclotron | 3880 | ||
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The design and construction of a radio frequency (RF) kicker system at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU) has been proposed. This RF kicker system will be used to purify secondary beams of rare isotopes after the existing A1900 Fragment Separator and will open a wide range of possibilities for new experiments at the forefront of nuclear science. The proposed system is studied as an efficient alternative to the traditional approach using Wien Filter. Rare neutron deficient secondary beams are challenging to purify because of the presence of intense contaminants that cannot be removed by the traditional energy loss method. However, velocity differences resulting in time-of-flight differences can be used for the effective separation of the beams transversely using the time-varying electromagnetic fields of the RF kicker. Its technical design will be presented together with the beam dynamics analysis of a secondary beam in realistic 3D electromagnetic fields. The expected purification improvement of the exotic beams for the foreseen nuclear physics experiments will be shown in details.
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| FPAT021 | Experience with Kicker Beam Coupling Reduction Techniques | impedance, extraction, simulation, vacuum | 1742 | ||
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SPS beam impedance is still one of the worries for operation with nominal LHC beam over longer periods once the final configuration will be installed in 2006. Several CERN SPS kickers suffer from significant beam induced ferrite heating. In specific cases, for instance beam scrubbing, the temperature of certain ferrite yokes went beyond the Curie point. Several retrofit impedance reduction techniques have been investigated theoretically and with practical tests. We report on experience gained during the 2004 SPS operation with restively coated ceramic inserts in terms of kicker heating, pulse rise time, operating voltage, and vacuum behavior. For another technique using interleaved metallic strips we observed significant improvements in bench measurements. Advantages and drawbacks of both methods and potential combinations of them are discussed and simulation as well as measured data are shown. Prospects for further improvements beyond 2006 are briefly outlined.
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| FPAT022 | Performance of the CERN SPS Fast Extraction for the CNGS Facility | extraction, damping, feedback, betatron | 1757 | ||
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The SPS LSS4 fast extraction system will serve both the anti-clockwise ring of the LHC and the long baseline neutrino (CNGS) facility. For the latter two extractions spaced by 50 ms, each affecting half of the ring, are foreseen. During the shutdown 2003-2004 the performance of the fast extraction kickers was improved in order to match more closely the specifications for the kicker pulse shape required for the CNGS and LHC extractions. The rise and fall times were significantly reduced, as well as the post-pulse kick ripple. However, the latter remains outside specifications and oscillations are induced in the leading bunches of the batch remaining in the machine at the moment of the first extraction. While further improving the characteristics of the kicker pulse shape, the possibility of damping the beam oscillations using the transverse feedback system has been explored. We report on the recent pulse form improvements and results of beam tests.
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| FPAT032 | NuMI Proton Kicker Extraction Magnet Termination Resistor System | impedance, radiation, extraction, proton | 2224 | ||
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Funding: Fermilab is operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the U.S. Department of Energy. |
The temperature stability of the kicker magnet termination resistor assembly directly affects the field flatness and amplitude stability of the kick. Comprehensive thermal enhancements were made to the existing Main Injector resistor assembly design to satisfy NuMI performance specifications. Additionally, a fluid-processing system utilizing Fluorinert® FC-77 high-voltage dielectric was built to precisely control the setpoint temperature of the resistor assembly from 70 to 120F, required to maintain constant resistance during changing operational modes. The Fluorinert® must be continually processed to remove hazardous breakdown products caused by radiation exposure to prevent chemical attack of system components. Design details of the termination resistor assembly and Fluorinert® processing system are described. Early performance results will be presented. |
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| FPAT090 | ExperimentDesigner: A Tcl/Tk Interface for Creating Experiments in EPICS | synchrotron, controls, monitoring, feedback | 4245 | ||
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Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
ExperimentDesigner is a Tcl/Tk interface that allows users to easily design and run complicated experiments using a convenient graphical user interface (GUI). Features include: process variable monitoring, which pauses the experiment when values are out of range; user-defined initialization, execution, and finalization sequences; support of complex execution chains containing actions such as setting controls, reading values, running external programs, interacting with the user, etc.; collection of output data for convenient postprocessing; saving and loading of experiment configurations; convenient use of SDDS Toolkit programs; and execution of experiments from the command line without a GUI. |
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