TU Darmstadt, Darmstadt
TEMF, TU Darmstadt, Darmstadt
The problem of self-consistent simulations of short relativistic particle bunches in long accelerator structures exhibits a pronounced multi-scale character. The adequate resolution of the THz space charge fields excited by short ultra-relativistic bunches requires mesh spacings in the micrometer range. On the other hand, the discretization of complete accelerator sections using such fine meshes results in a vast number of degrees of freedom. Due to the spatial concentration of the particles and the excited space charge fields, the application of time-adaptive mesh refinement is an emerging idea. We reported on the implementation of time-adaptive mesh refinement for the Finite Integration Technique (FIT)*. Based on this work, we implemented an hp-adaptive discontinuous Galerkin (DG) code. The twofold refinement mechanisms of the hp-adaptive DG method offer maximum modeling freedom. We present details of the h- and p-adaptations for the DG method on Cartesian grids. Special emphasis is put on the stability and efficiency of the adaptation techniques.
Muroran Institute of Technology, Department of Electrical and Electronic Engineering, Muroran
In addition to standard high performance computing technologies such as supercomputers and grid computers, a method of dedicated computers have been attempted to construct portable high performance computing environments in the vicinity of office PC. The method of dedicated computers have also been adopted into electromagnetic field simulations, which are mainly in a linear algebra equation solver for general electromagnetic field analysis and the FDTD solver for microwave simulations. In this paper, attempts of FDTD/FIT dedicated computer (FDTD/FIT machine) are introduced*. The basic scheme of the FDTD/FIT method itself is very simple and suitable for implementation as hardware circuits. In addition, it is also essential to realize many other functions such as imposing of boundary conditions, treatment of non-uniform materials, power input, etc. Moreover, to fully bring out the advantage of the method of dedicated computer, the computer architecture should be designed to achieve efficient computing of all of FDTD/FIT scheme including the boundary condition setting, etc. Especially various efforts of minimization of memory access overhead are discussed in this paper.
JLAB, Newport News, Virginia
In this paper, we present benchmarking results for high-class 3D electromagnetic (EM) codes in designing RF cavities today. These codes include Omega3P [1], VORPAL [2], CST Microwave Studio [3], Ansoft HFSS [4], and ANSYS [5]. Two spherical cavities are selected as the benchmark models. We have compared not only the accuracy of resonant frequencies, but also that of surface EM fields, which are critical for superconducting RF cavities. By removing degenerated modes, we calculate all the resonant modes up to 10 GHz with similar mesh densities, so that the geometry approximation and field interpolation error related to the wavelength can be observed.
ORNL, Oak Ridge, Tennessee
The laser assisted hydrogen stripping becomes a widely discussed alternative for the existing stripping foil approach. The simulation tool for this new approach is presented. The created application is implemented in form of extension module to Python ORBIT parallel code that is under development at the SNS. The physical model of the application deals with quantum theory and allows calculating evolution and ionization of hydrogen atoms and ions affected by superposition of electromagnetic and laser fields. The algorithm, structure, benchmark cases, and results of simulations for several future and existing accelerators are discussed.