LBNL, Berkeley, California
ICST, Harbin
UMiss, University, Mississippi
Funding: This work is supported by funds under the “985-2” plan of HIT. This work is also supported by the Office of Science, US-DOE under DOE contract DE-AC02-05CH11231 and by NSF through NSF-MRI-0722656.
The superconducting coupling solenoid for MuCOOL and MICE will have an inside radius of 750 mm, and a coil length of 285 mm. The MuCOOL coupling coil is identical to the MICE coupling coils. The MICE coupling magnet will have a self inductance of 592 H. When operated at it maximum design current of 210 A (the highest momentum operation of MICE), the magnet stored energy will be about 13 MJ. These magnets will be kept cold using a pair of pulse tube cryocoolers that deliver 1.5 W at 4.2 K and 55 W at 60 K. This report describes the progress on the MuCOOL and MICE coupling magnet design and engineering. The progress on the construction of the first coupling coil will also be presented.
IHEP Beijing, Beijing
China Spallation Neutron Source is a high intensity beam facility planed to build in future in China. It is composed of Linac, RCS and target station. The beam extraction from the RCS will be realized by ten vertical kicker magnet and one Lambertson magnet. One prototype kicker magnet has been successfully designed and developed in Institute of High Energy Physics. In this paper, the physical and structural design of the prototype kicker magnet are presented, and issues of the magnet development, construction and test are discussed.
IHEP Beijing, Beijing
China Spallation Neutron Source is a high intensity beam facility planed to build in future in China. It is composed of Linac, RCS and target station. Two sets of pulsed painting bump magnets, 4 magnets in each set , will be used in CSNS RCS to create a dynamic orbit bump for injection process. The design of these 8 bump magnets has been completed. One prototype bump magnet has been assembled and tested. In this paper, the magnetic field analysis, the eddy current and thermal consideration in the end plates of the prototype bump magnet are presented, and issues of the magnet development, construction and test are discussed.
LLNL, Livermore, California
TomoTherapy, Madison
CPAC, Madison
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We are developing a compact proton accelerator for cancer treatment by using the dielectric high-gradient insulator wall technology. The goal is to fit the compact dielectric wall proton therapy machine inside a conventional treatment room. To make the proton dielectric wall accelerator (DWA) compact requires a compact proton source capable of delivering protons in a sub-ns bunch. We are testing all the essential DWA components, including the compact proton source, on the First Accelerator System Test (FAST), which is designed to be taken apart and rebuilt many times to increase system performance by using improved components. The proton source being investigated currently is a surface flashover source. Five induction cells with HGI in the acceleration gaps are used to provide the 300-keV, 20-ns injector voltage for the proton injector. The physics design and the configuration of the injector and FAST will be presented.
LLNL, Livermore, California
TomoTherapy, Madison
TPL, Albuquerque, NM
CPAC, Madison
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livvermore National Laboratory under Contract DE-AC52-07NA27344.
The dielectric wall accelerator* (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.
*Patents pending.
LBNL, Berkeley, California
LLNL, Livermore, California
SLAC, Menlo Park, California
Funding: This work was supported by the Office of Science, U. S. Department of Energy, under Contract No. DE-AC02-05CH11231.
A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb << 2*π/ωc, (lb = bunch duration, ωc = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor of approximately 3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined density "stripes" of multipactoring found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations, the reason for the bunch-length dependence, and details of the dynamics will be discussed.
C.M. Celata is presently also a visitor in Physics, Mathematics, and Astronomy at California Institute of Technology.
SLAC, Menlo Park, California
Stanford University, Stanford, California
UCLA, Los Angeles, California
Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
SSRL and SLAC groups are developing a long-range plan to transfer its evolving scientific programs from the SPEAR3 light source to a much higher performing photon source that would be housed in the 2.2-km PEP-II tunnel. While various concepts for the PEP-X light source are under consideration, including ultimate storage ring and ERL configurations, the present baseline design is a very low-emittance storage ring. A hybrid lattice has DBA or QBA cells in two of the six arcs that provide a total ~30 straight sections for ID beam lines extending into two new experimental halls. The remaining arcs contain TME cells. Using ~100 m of damping wigglers the horizontal emittance at 4.5 GeV would be ~0.1 nm-rad with >1 A stored beam. PEP-X will produce photon beams having brightnesses near 1022 at 10 keV. Studies indicate that a ~100-m undulator could have FEL gain and brightness enhancement at soft x-ray wavelengths with the stored beam. Crab cavities or other beam manipulation systems could be used to reduce bunch length or otherwise enhance photon emission properties. The present status of the PEP-X lattice and beam line designs are presented and other implementation options are discussed.
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: The Japan/US Cooperation Program
Beam instability caused by the electron cloud is expected to be a limiting factor in the performance of future advanced positron and proton storage rings. In a wiggler section of the positron ring of the KEK B-factory (KEKB), we have installed a vacuum chamber with an insertion that can be replaced and including different techniques to study the mitigation of the electron-cloud effect in a high magnetic field region. We have installed an insertion with strip-line clearing electrode, an insertion with triangular grooves and an insertion with a smooth surface, and compared them each other under the same conditions. The electrode insertion is composed of a thin tungsten layer formed on a thin alumina ceramic layer. The groove insertion is composed of TiN-coated triangular grooves running longitudinally. In this paper, we report about the tests in the KEKB and about the large reduction in the measured electron cloud density when the clearing electrode and groove sections are installed with respect to the smooth insertion. These experiments are the first ones demonstrating the principle of the clearing electrode and groove insertions in a magnetic field.
SLAC, Menlo Park, California
A proposed high-brightness synchrotron light source (PEP-X) is under design at SLAC. The 4.5-GeV PEP-X storage ring has four theoretical minimum emittance (TME) cells to achieve the very low emittance and two double-bend achromat (DBA) cells to provide spaces for IDs. Damping wigglers will be installed in zero-dispersion straights to reduce the emittance below 0.1nm. In this paper, we present a preliminary estimation of the threshold of the transverse mode coupling instability(TMCI). Three approaches have been used in the estimation and they agree well with each other.
SLAC, Menlo Park, California
A proposed high-brightness synchrotron light source (PEP-X) is under design at SLAC. The 4.5-GeV PEP-X storage ring has four theoretical minimum emittance (TME) cells to achieve the very low emittance and two double-bend achromat (DBA) cells to provide spaces for IDs. Damping wigglers will be installed in zero-dispersion straights to reduce the emittance below 0.1 nm. Ion induced beam instability is one critical issue due to its ultra small emittance. Third harmonic cavity can be used to lengthen the bunch in order to improve the beam life time. Bunch-train filling pattern is proposed to mitigate both the fast ion instability and beam loading effect. This paper investigates the fast ion instability and beam loading for different beam filling patterns.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
KEK, Ibaraki
ANL, Argonne
Fermilab, Batavia
CalPoly, San Luis Obispo, CA
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
SLAC, Menlo Park, California
Cornell University, Ithaca, New York
Cockcroft Institute, Warrington, Cheshire
Funding: Support provided by the US National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program.
In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
ANL, Argonne
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: Supported by the US National Science Foundation, the US Department of Energy under Contracts No. DE-AC02-06CH11357, DE-AC02-05CH11231, and DE-AC02-76SF00515, and by the Japan/US Cooperation Program.
CESR at Cornell has been operating as a damping ring test accelerator (CesrTA) with beam parameters approaching those anticipated for the ILC damping rings. A core component of the research program is to fully understand electron cloud effects in CesrTA. As a local probe of the electron cloud, several segmented retarding field analyzers (RFAs) have been installed in CesrTA in dipole, drift and wiggler regions. Using these RFAs, the energy spectrum of the time-average electron cloud current density striking the walls has been measured for a variety of bunch train patterns; with bunch populations up to 2x1010 per bunch, beam energies from 2 to 5 GeV, horizontal geometric emittances from roughly 10 to 133 nm, and bunch lengths of about 1 cm; and for both positron and electron beams. The effect of mitigation measures, such as coatings, has also been studied. This paper will compare these measurements with the predictions of simulation programs, and discuss the implications of these comparisons for our understanding of the physics of electron cloud generation and mitigation in ILC-like damping rings.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
ANL, Argonne
CalPoly, San Luis Obispo, CA
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: National Science Foundation award 0734867 Office of Science, U.S. Department of Energy contracts DE-AC02-05CH11231 and DE-AC02-06CH11357
The Cornell Electron Storage Ring Test Accelerator (CesrTA) has commenced operation as a linear collider damping ring test bed following its conversion from an e+e- collider in 2008. A core component of the research program is the measurement of effects of synchrotron-radiation-induced electron cloud formation on beam dynamics. We have studied the interaction of the beam with the cloud in a number of experiments, including measurements of coherent tune shifts and emittance growth in various bunch train configurations, with different bunch currents, beam energies, beam emittance, and bunch lengths, for both positron and electron beams. This paper compares these measurements to modeling results from several advanced cloud simulation algorithms and discusses the implications of these comparisons for our understanding of the physics of electron cloud formation and decay in damping rings of the type proposed for future high-energy linear colliders.
USTC/NSRL, Hefei, Anhui
HALS(Hefei Advanced Light Source) is the electron storage ring of ultra-low emittance in process of design. Under this design, the quadrupole magnet with sextupole component must be mounted on which the βη is much bigger, to use enough the effect of compersation chromaticity of sextupole magnet field and to use sparingly the space in the same time . So the combined quadrupole and sextupole magnet must be designed, and have more strong sextupole component and restrain the production of high harmonic field. In this paper, the chocie of design scheme is discussed, and the calculation of combined quadrupole and sextupole mangnet design is given.
USTC/NSRL, Hefei, Anhui
Hefei Light Source is a second generation VUV light source, whose performance cannot meet the requirements of synchrotron radiation users at the present time. One year ago, the concept of the Hefei Advanced Light Source, whose main features are ultra low beam emittance and high brilliance in VUV and soft X-ray range, was brought forward. In the preliminary design study, a medium scale storage ring and multi bend achromat focusing structure were adopted to achieve beam emittance lower than 0.2 nm.rad. Linear and nonlinear parameter optimizations were performed to obtain large on-momentum and off-momentum dynamic aperture. The design status will be introduced briefly in the presentation.
USTC/NSRL, Hefei, Anhui
Funding: supported by National Natural Science Foundation of China (10705027)
Hefei Advanced Light Source(HALS) is a super low emittance storage ring and has a very poor beam life time. In order to run the ring stablely, Top-up injection will be necessary. Injection system will greatly affect the quality of beam. This article first give a physics design of injecting system. Then the injecting system is tracked under different errors. The responses of storage beam and injecting beam is given in the article.
USTC/NSRL, Hefei, Anhui
A bunch-by-bunch analogue transverse feedback system at the Hefei Light Source (HLS) is to cure the resistive wall instability and the transverse coupled bunch instabilities. The kicker of the feedback system has four 21-cm-long electrodes of stripline type mounted in a skew 45°. Calculation and Simulation of the transverse kicker are shown.
USTC/NSRL, Hefei, Anhui
IHEP Beiing, Beijing
SINAP, Shanghai
IHEP Beijing, Beijing
SSRF, Shanghai
In this paper, we introduce the BxB transverse feedback systems at Hefei Light Source (HLS), which employ an analog system and a digital system. The construction and commissioning for two feedback systems, as well as the instability analysis of beam and the experiment result of the feedback system in HLS are also presented in this paper.
USTC/NSRL, Hefei, Anhui
As low injection energy and multi-turn injection at HLS, the task of diagnosing and curing coupled-bunch instabilities becomes ever harder. The transverse analog feedback system has been redeveloped to improve effect, recently. In this paper, the new improved designs are described and new system's commissioning results are discussed. The transverse coupled bunch instability at 200MeV injection status is also experimentally studied.
USTC/NSRL, Hefei, Anhui
JASRI/SPring-8, Hyogo-ken
Hefei Light Source (HLS) is an 800MeV storage ring with bunch rate of 204 MHz, the harmonics of 45, and circumference of 66 meters. HLS injection works at 200MeV, where the multi-bunch instabilities limit the maximum stored current. A digital transverse bunch-by-bunch feedback system has recently been commissioned at HLS to suppress the multi-bunch instabilities during injection. We employ the SPring-8 FPGA based feedback processor and modified it at NSRL to process horizontal and vertical oscillation signals, independently and simultaneously by one single processor. The design of the digital transverse feedback system and the experiment results are presented in this paper.
USTC/NSRL, Hefei, Anhui
In order to meet the increasing requirements of synchrotron radiation users, a new plan of VUV and soft X-ray light source, named Hefei Advanced Light Source (HALS), is brought forward by National Synchrotron Radiation Laboratory (NSRL). This 1.5GeV storage ring with ultra low emittance 0.2nmrad consists of 18 combined FBA cells and the circumference is 388m. Strong enough quadrupoles and sextupoles must be needed for getting such low emittance lattice, which will lead beam close orbit distortions’ (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. Using orbit response matrix and singular value decomposition method, the distribution of beam position monitors and the location of correctors are reported in the paper. Simulation proves that COD can be corrected down to 60 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.