CST, Darmstadt
Due to high demand in more realistic graphics rendering for computer games and professional applications, commercial, off-the-shelf graphics processing units (GPU) increased their functionality over time. Recently special application programming interfaces (API) allow programming these devices for general purpose computing. This talk will discuss the advantages of this hardware platform for time domain simulations using the Finite-Integration-Technique (FIT). Examples will demonstrate typical accelerations over conventional central processing units (CPU). Next to this hardware-based accelerations for simulations also software-based accelerations are discussed. A distributed computing scheme can be used to accelerate multiple independent simulation runs. For memory intense simulations the established Message Passing Interface (MPI) protocol enables distribution of one simulation to a compute cluster with distributed memory access. Finally, the FIT framework also allows special algorithmic improvements for the treatment of curved shapes using the perfect boundary approximation (PBA), which speeds up simulations.
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.
ANL, Argonne
Beam scattering effects, including intra-beam scattering (IBS) and Touschek scattering, may become an issue for linac-based 4th-generation light sources, such as X-ray free-electron lasers (FELs) and energy recovery linacs (ERLs), as the electron density inside the bunch is very high. In this paper, we describe simulation tools for modeling beam-scattering effects that were recently developed at the Advanced Photon Source (APS). We also demonstrate their application to a possible ERL-based APS upgrade. The beam loss issue due to the Touschek scattering effect is addressed through momentum aperture optimization. The consequences of IBS for brightness, FEL gain, and other figures of merit are also discussed. Calculations are performed using a particle distribution generated by an optimized high-brightness injector simulation.
GSI, Darmstadt
ITEP, Moscow
IAP, Frankfurt am Main
During the last year several numerical investigations have been started at GSI in order to improve the performance of the linear accelerator facility. The main activities regard the upgrade of the high current UNILAC accelerator including the severe upgrade of the HSI injector, the HITRAP decelerator and, in the frame of the future FAIR project, the development of the new dedicated proton linac. End to end beam dynamics simulations are a powerful tool concerning the machine design, commissioning and optimization. Particle distributions, generated from beam emittance measurements, are transferred through the whole chain of the accelerating structures and beam transport lines. Detailed calculations of the space charge effects as well as external and measured mapping of the structures electromagnetic fields are used to provide the most reliable results. The paper presents a general overview of all activities including a comparison with experimental results.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
BNL, Upton, Long Island, New York
The beam commissioning of J-PARC linac has been performed since November 2006, and we are now in a transitional phase from an initial commissioning stage to a stage where we seek more stable operation with higher beam power. In the beam commissioning, the modeling is important to understand the underlying physics of the experimental data obtained by beam monitors. As the J-PARC is a high-intensity proton accelerator facility, the beam is subject to strong space-charge effects. In addition, mitigation of the beam loss is critically important to avoid excess radio-activation of the accelerator components. Therefore, an accurate Particle-In-Cell simulation code plays an essential role in the beam commissioning, especially in mapping out our course in the beam commissioning planning. For this purpose, we have been using IMPACT code in J-PARC linac. In this paper, we review the simulation studies performed for J-PARC linac trying to understand the experimental results in the course of the beam commissioning efforts.
ANL, Argonne
Optimization tools are needed in every step of an accelerator project, from the design to commissioning to operations. However, different phases have different optimization needs that may require different optimization algorithms. For example, a global optimizer is more appropriate in the design phase to map the whole parameter space whereas a local optimizer with a shorter path to solution is more adequate during operations to find the next best operating point. Different optimization algorithms are being used in accelerator physics, we mention in particular standard algorithms based on least square minimization and evolutionary algorithms such as genetic optimizers. Over the years, we have developed several optimization tools for beam tracking codes to include 3D fields and SC effects. Including particle tracking in the optimization process calls for parallel computing. We will review the different algorithms and their implementation and present few highlight applications.
TRIUMF, Vancouver
DAE/VECC, Calcutta
SFU, Burnaby, BC
The TRIUMF-VECC Electron Linac is a device for gamma-ray induced fission of actinide targets, with applications in nuclear physics and material science. A phased construction and commissioning scheme will eventually lead to a 50 MeV, 10 mA CW linac based on superconducting RF technology. Using this linac to deliver high intensity electron beams for applications such as an energy-recovered light source is a possibility integrated in the design study. The multitude of design and tuning parameters, diverse objectives and constraints require a comprehensive and efficient optimization scheme. For this purpose we adopted the genetic optimization program developed at Cornell University* as a prototype. Feature extensions were developed to accommodate specifics of the Electron Linac design, provide framework for more generic and integrated design process, and perform robustness/acceptance analyses. In this report we will discuss the method and its application to the design optimization of the Electron Linac. [1]. I. Bazarov and C. Sinclair, PRST-AB 8, 034202 (2005), and references therein.
SLAC, Menlo Park, California
An x-ray Free-Electron Laser (FEL) calls for a high brightness electron beam. Generically, such a beam needs to be accelerated to high energy on the GeV level and compressed down to tens of microns, if not a few microns. The very bright electron beam required for the FEL has to be stable and the high quality of the electron beam has to be preserved during the acceleration and bunch compression. With a newly developed model independent global optimizer [*], here we report study for the control and error diagnostics of such a generic machine: magnetic elements, and RF cavities, and the electron beam parameters: the peak current, centroid energy, and trajectory. Collective effects, such as coherent synchrotron radiation, space charge, and various wakefields are incorporated in a parametric approach. Applicability and verification are detailed for the LINAC Coherent Light Source, an x-ray FEL project being commissioned at SLAC.
Fermilab, Batavia
In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the ILC acceleration structure. The RF kick was calculated by HFSS code while the wake was calculated by GdfidL. The calculation precision and convergence for both cases is discussed. The beam emittance dilution caused by the couplers is calculated for the main linac and bunch compressor of ILC.
Fermilab, Batavia
Similar to many other linear accelerators, the High Intensity Neutron Source requires an RFQ for initial acceleration and formation of the bunched beam structure. The RFQ design includes two main tasks: a) the beam dynamics design resulting in a vane tip modulation table for machining and b) the resonator electromagnetic design resulting in the final dimensions of the resonator. The focus of this paper is on the second task including simulating high power operation of RFQ. We report complete and detailed RF modeling on the HINS RFQ resonator using simulating codes CST Microwave Studio (MWS) and Ansoft High Frequency Structure Simulator (HFSS). All details of the resonator such as input and output radial matchers, the end cut-backs etc have been precisely determined. In the first time a full size RFQ model with modulated vane tips, the power couplers and all tuners installed has been built, and a complete simulation of RFQ tuning has been performed. Finally some aspects of high power operation of RFQ have been investigated. Comparison of the simulation results with experimental measurements demonstrated excellent agreement.
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.