Diamond, Oxfordshire
JAI, Oxford
The Diamond light source started operation for users in January 2007. With the successful commissioning of the nominal optics, delivering a 2.75 nm emittance beam at 3 GeV, we now routinely provide the users with a 250 mA beam with a lifetime of >20 h, exceeding the minimum specified current-lifetime product of 3000 mAh. Driven by the necessity to guarantee a correct implementation of the nonlinear optics, a significant experimental and theoretical effort is ongoing to understand and improve the nonlinear beam dynamics in the storage ring. The necessity to control the nonlinear beam dynamics is even more urgent with the installation of a large number of small gap (5 mm) in-vacuum insertion device and the need to control the injection efficiency with Top-Up operation. We report here the present status of the analysis of the nonlinear beam dynamics and the main experimental results.
ANL, Argonne
BNL, Upton, Long Island, New York
ELEGANT is an open-source accelerator code that has been under development for approximately two decades. In that time, it has evolved from a graduate student project with a narrow purpose to a general code for the design and modeling of linacs and storage rings. ELEGANT continues to evolve, thanks in no small part to suggestions from users. ELEGANT has seen extensive application to modeling of linacs, particularly for applications related to free-electron lasers and energy recovery linacs. Recent developments have emphasized both linac and storage-ring-related enhancements, along with parallelization. In this paper, we briefly review the features of ELEGANT and its program suite. We then describe some of the recent progress made in the ongoing development of ELEGANT. We also discuss several noteworthy applications and directions for future work.
HU/AdSM, Higashi-Hiroshima
JAEA/Kansai, Kyoto
TUB, Beijing
JAEA/TARRI, Gunma-ken
An ultimate goal in accelerator physics is to produce a "zero-emittance" beam, which is equivalent to making the beam temperature the absolute zero in the center-of-mass frame. At this limit, if somehow reached, the beam is Coulomb crystallized. Schiffer and co-workers first applied the molecular dynamics (MD) technique to study the fundamental features of various Coulomb crystals. Their pioneering work was later generalized by Wei et al. who explicitly incorporated discrete alternating-gradient lattice structures into MD simulations. This talk summarizes recent numerical efforts made to clarify the dynamic behavior of ultra-cold and crystalline ion beams. The MD modeling of beam crystallization in a storage ring is outlined, including how one can approach the ultra-low emittance limit. Several possible methods are described of cooling an ion beam three-dimensionally with radiation pressure (the Doppler laser cooling).
ANL, Argonne
BNL, Upton, Long Island, New York
Optimization of dynamic and momentum apertures is one of the most challenging problems in storage ring design. For storage-ring-based x-ray sources, large dynamic aperture is important in obtaining high injection efficiency, which leads to efficient operation and protects components from radiation damage. X-ray sources require large momentum aperture to obtain sufficiently long Touschek lifetimes with low-emittance beams. We have developed effective methods of optimizing dynamic and momentum apertures that rely directly on tracking using a moderately sized Linux cluster. After reviewing the method, we present examples of its application to APS operations, upgrades, and next-generation storage rings.
KIT, Karlsruhe
FZK, Karlsruhe
ANKA is a synchrotron radiation source located in Karlsruhe, Germany. While the control system has always provided access to technical parameters, like power supply currents or RF frequency, direct access to physical parameters like tune or chromaticity has been missing. Thus the operator has to change and monitor the technical parameters manually and to calculate the physical parameters using separate tools. Therefore effort has been made to integrate the monitoring of physical parameters and simulation tools into the control system. At ANKA the MATLAB-based Accelerator Toolbox is used for simulation purposes, however the control system framework ("ACS") does not support MATLAB natively. For this reason, a software bridge has been created, which provides direct access to control system components from MATLAB. Thus operators can write their own MATLAB code simultaneously using simulation code and components from the control system. This system has already been used to automate measurements, thus allowing unattended long-term measurements, which have not been possible before. Future plans include creating a graphical user interface and various monitoring and stabilization loops.
ANL, Argonne
The electron accelerator simulation software elegant is being parallelized in a multi-year effort. Recent developments include parallelization of input/output (I/O), frequency map analysis, and position-dependent momentum aperture determination. Parallel frequency map and momentum aperture analysis provide rapid turnaround for two important determinants of storage ring performance. Recent development of parallel Self-Describing Data Sets file (SDDS) I/O based on MPI-IO made it possible for parallel elegant (Pelegant) to take advantage of parallel I/O. Compared with previous versions of Pelegant with serial I/O, the new version not only enhances the I/O throughput with a good scalability, but also provides a feasible way to run simulations with a very large number of particles (e.g., 1 billion particles) by eliminating the memory bottleneck on the master with serial I/O. Another benefit of using parallel I/O is reducing the communication overhead significantly for the tracking of diagnostic optical elements, where the particle information has to be gathered to the master for serial I/O.
SLAC, Menlo Park, California
In a multi-bunch high current storage ring, beam generated fields couple strongly into the RF cavity coupler structure when beam arrival times are in resonance with cavity fields. In this study the integrated effect of beam fields over a several thousand RF periods is simulated for the complete cavity, coupler, window and waveguide system of the PEP-II B-factory storage ring collider. We show that the beam generated fields at frequencies corresponding to several bunch spacings for this case gives rise to high field strength near the ceramic window and could limit the performance of future high current storage rings such as PEP-X or Super B-factories.
SLAC, Menlo Park, California
High current B-Factory BPM designs incorporate a button type electrode which introduces a small gap between the button and the beam chamber. For achievable currents and bunch lengths, simulations indicate that potentials can be induced in this gap which are comparable to the breakdown voltage. This study characterizes beam induced voltages in the existing PEP-II storage ring collider BPM as a function of bunch length and beam current.