TUODN —  Beam Dynamics V   (29-Mar-11   16:00—17:30)
Chair: R.O. Hettel, SLAC, Menlo Park, California, USA
Paper Title Page
TUODN1 CSR Fields From Using a Direct Numerical Solution of Maxwell's Equations 784
 
  • A. Novokhatski
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
We discuss the properties of the coherent electromagnetic fields of a very short, ultra-relativistic bunch in a rectangular vacuum chamber inside a bending magnet. The analysis is based on the results of a direct numerical solution of Maxwell’s equations together with Newton’s equations. We use a new dispersion-free time-domain algorithm which employs a more efficient use of finite element mesh techniques and hence produces self-consistent and stable solutions for very short bunches. We investigate the fine structure of the CSR fields including coherent edge radiation. This approach should be useful in the study of existing and future concepts of particle accelerators and ultrafast coherent light sources.
 
slides icon Slides TUODN1 [8.690 MB]  
 
TUODN2 Exploration of Parallel Optimization Techniques for Accelerator Design 787
 
  • Y. Wang, M. Borland, V. Sajaev
    ANL, Argonne, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Optimization through simulation is a time-consuming task in accelerator design, especially for high dimensional problems. We explored several parallel optimization techniques, including Parallel Genetic Algorithm (PGA), Hybrid Parallel Simplex (HPS), and Parallel Particle Swarm Optimization (PPSO), to solve some real world problems. The serial simplex method in elegant was used as a benchmark for newly-developed parallel optimization algorithms in Pelegant. PGA and HPS are not faster than the serial simplex method, but they more reliably find the global optimum. PPSO is well suited for parallel computing, allowing significantly faster turn-around given sufficient computing resources. Parallel optimization implementations in Pelegant thus promise to not only make optimization results more reliable, but also open the possibility of fast, "real time" optimization of complex problems for accelerator operation.
 
slides icon Slides TUODN2 [0.218 MB]  
 
TUODN3 Beam Dynamics Studies of Parallel-Bar Deflecting Cavities 790
 
  • S. Ahmed, J.R. Delayen, A.S. Hofler, G.A. Krafft, M. Spata, M.G. Tiefenback
    JLAB, Newport News, Virginia, USA
  • K.B. Beard
    Muons, Inc, Batavia, USA
  • K.A. Deitrick
    RPI, Troy, New York, USA
  • S.D. Silva
    ODU, Norfolk, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.
 
slides icon Slides TUODN3 [1.558 MB]  
 
TUODN4 Dynamic Aperture Optimization using Genetic Algorithms 793
 
  • C. Sun, H. Nishimura, D. Robin, C. Steier, W. Wan
    LBNL, Berkeley, California, USA
 
  Genetic Algorithm is successfully applied to optimize dynamic aperture of lattices for ALS future upgrades. It is demonstrated that the optimization using total diffusion rate as objective has a better performance than the one using dynamic aperture area. The linear and non-linear properties of the lattice are optimized simultaneously, and trade-offs are found among the small emittance, low-beta function and large dynamic aperture. These trade-offs can provide us a guideline to choose a candidate lattice for ALS future upgrades.  
slides icon Slides TUODN4 [1.781 MB]  
 
TUODN5
High Fidelity Calculation of Wakefields for Short Bunches  
 
  • C.-K. Ng, A.E. Candel, K. Ko, V. Rawat, G.L. Schussman, L. Xiao
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by DOE ASCR, BES & HEP Divisions under contract DE-AC02-76SF00515.
The determination of wakefields for short bunches in accelerator structures with complex geometries and large spatial dimensions requires significant computational resources. The time domain code T3P developed at SLAC employs the higher-order finite element method for high fidelity modeling and parallel computation for large-scale simulation on state-of-the-art supercomputers. To facilitate wakefield calculation for short bunches, T3P has been enhanced through the implementation of a moving window technique which reduces computing resource requirements by orders of magnitude. For local refinement in the moving window, both a finer unstructured mesh and higher-order finite element basis functions can be employed. Applications demonstrating the efficacy of the technique include wakefield calculations of shallow tapers in storage rings, complex and long vacuum chamber transitions in energy recovery linacs (ERL) and higher-order-mode (HOM) couplers in superconducting rf cavities.
 
slides icon Slides TUODN5 [144.213 MB]  
 
TUODN6 Action and Phase Jump Analysis for LHC Orbits 796
 
  • O.R. Blanco, J.F. Cardona
    UNAL, Bogota D.C, Colombia
 
  Funding: COLCIENCIAS, Programa Jovenes Investigadores e Innovadores "Virginia Gutierrez de Pineda" 2009 Direccion de Investigacion Sede Bogota, Universidad Nacional de Colombia (DIB, UNAL)
Action and phase orbit correction method is implemented to detect magnetic errors in LHC orbits of late 2009 run. The last achievements in the theory of action and phase jump analysis have been included to reduce action and phase plots noise and to increase precision on the calculation of linear errors. The validation of the implementation is performed by MAD-X simulations of the LHC lattice V6.5, where dipole and quadrupole errors are included and recovered within 0.02%. Then, the implementation is applied to experimental orbits, taken from the 2009 run during November and December, where several interaction regions are analyzed.
orblancog@bt.unal.edu.co, Universidad Nacional de Colombia
jfcardona@unal.edu.co, Professor, Universidad Nacional de Colombia
 
slides icon Slides TUODN6 [1.867 MB]