ESS, Lund, Sweden
ORNL, Oak Ridge, Tennessee, USA
Linac dynamics simulation capabilities of the PyORBIT code are discussed. The PyORBIT is an open source and a further development of the original ORBIT code that was developed and used for design, studies, and commissioning of the SNS ring. The PyORBIT code like the original one has a two layers structure. The C++ is used to perform time consuming computations, and a program flow is controlled from the Python language shell. The flexible structure allowed using the PyORBIT also for linac dynamics simulations. The benchmark of the PyORBIT with Parmila and the XAL Online model is presented.
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
Multi-objective genetic algorithms (MOGA) have demonstrated their usefulness for the global optimization of accelerator design using Elegant and Astra. A MOGA platform developed at TRIUMF seeks to expand the capabilities of such tools by allowing multiple simulation engines to be used. The TRIUMF optimization software platform was applied to the transport design of an injection line leading from a cryomodule to the beam dump. The optimization involves two simulation engines, Astra and MAD-X, and demonstrates the ability for the platform to handle multi-engine optimization for a realistic problem. Results of the optimization are shown.
Diamond, Oxfordshire, United Kingdom
BNL, Upton, Long Island, New York, USA
TU Darmstadt, Darmstadt, Germany
In order to test RF control systems for accelerator cavities without being dependent on available prototypes, a resonator-simulator has been developed. The Simulator is based on a Xilinx-VIRTEX-4 FPGA-module and has been configured using MATLAB-Simulink with a special Xilinx-Blockset. The underlying model for this configuration is a parallel RLC-circuit that has been parameterised with common RF-quantities like the resonance frequency, driving frequency, bandwidth and quality factor. This approach allows to simulate the behaviour of normal conducting cavities with quality factors up to 104 as well as superconducting cavities with quality factors up to 109. Besides, it can as well be operated in a continuous-wave as in a pulsed mode. We report on the mathematical model, its digital representation and on the benchmarking against real cavity behaviour.
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
HZB, Berlin, Germany
Energy Recovery Linacs (ERLs) being the most promising candidates for next-generation light sources put very high demands on preservation of beam brightness and reduction of beam losses. Thus, it is mandatory to avoid the impact of ionized residual gas considered as a source for instabilities in accelerators. Recently, we have presented simulations for the clearing of ionized residual gas with electrodes performed with an upgraded version of software package MOEVE PIC Tracking [1] which is being currently further developed to model the interaction of the ions with the electron beam in presence of external electromagnetic potentials such as the field of clearing electrodes. The tracking code allows for studies on clearing times for electrodes with different voltage as well as detailed studies of the behavior of the ions in the environment of the electrodes. In this paper we take further steps to study possible designs of clearing electrodes. Especially, we will consider the influence of different gas mixtures on clearing times and possible configurations for the clearing electrodes. We use parameters planned for BERLinPro as an example for our studies.
[1] G. Pöplau, A. Meseck, U. van Rienen, Simulation of the Behavior of Ionized Residual Gas in the Field of Electrodes, IPAC 2012, New Orleans.
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
HZB, Berlin, Germany
DELTA, Dortmund, Germany
The main scope of this work is the automation of the extraction procedure of the external quality factors Qext of Higher Order Modes (HOMs) in Superconducting (SC) radio frequency cavities [*]. The HOMs are generated by charged particle beams traveling at the speed of light through SC cavity. The HOMs decay very slowly, depending on localization inside the structure and cell-to-cell coupling, and may influence succeeding charged particle bunches. Thus it is important, at the SC cavity design optimization stage, to calculate the Qext of HOMs. The Traveling Poles Elimination (TPE) scheme has been used on scattering parameters spectra to obtain external quality factors. The combination of Coupled S-Parameter Calculations (CSC) method and vector fitting procedure allows us to study very complicated structures in much better details and almost automated extraction of HOMs' Qext factors. The results are also reasserted by careful eigenmode analysis of the SC cavity. The S-Parameter and eigenmode simulations were performed using CST Microwave Studio.
*Axel Neumann et al., "Status of the HOM Calculations for the BERLinPro Main Linac Cavity", FRAAC3 (this conference)
DELTA, Dortmund, Germany
HZB, Berlin, Germany
Elliptical cavities have been a standard in SRF linac technology for 30 years. In this work, we present a novel approach [1] using Bezier spline profile curves. By using different degrees of spline curves, the number of free parameters can be varied to suit a given problem (endcell tuning, basecell figures of merit), thus leading to a high flexibility of the spline approach. As a realistic example, a cubic spline SRF multicell cavity geometry is calculated and the figures of merit are optimized for the operational mode. We also present an outline for HOM endcell optimization that can be realized using available 2D solvers.
[1] B. Riemann et al., "SRF multicell cavity design using cubic and higher order spline cavity profiles", T 80.9, Verhandlungen DPG Göttingen 2012
GSI, Darmstadt, Germany
Fermilab, Batavia, USA
The computational approaches assure essential guidance and order for the design of a superconducting cavities and cryomodules. The nature of superconductivity requires precise surface electromagnetic fields computation in order to design the cavity shape with a maximum accelerating gradient. At the same time the thickness of the cavity shell is limited by the ability to cool it down the temperature of liquid He, which makes the mechanical stability of the cavity and liquid He vessel assembly extremely important. Hence, it demands a self consistent electro-mechanical optimization in order to minimize microphonics and/or Lorentz force detuning phenomena. Specific challenges are an estimation of RF losses caused by the interaction of the passing beam with SC cavity and a multipactor analysis in the SC cavity and RF coupler. Finally the irregular time structure of a beam train with its own dense spectra may stochastically induce HOM fields in a cavity which results the beam emittance dilution. The study of these effects leads to specifications of SC cavity and cryomodule and can significantly impact on the efficiency and reliability of the superconducting linac operation.
HZB, Berlin, Germany
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
DELTA, Dortmund, Germany
The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology and expertise required to drive next-generation Energy Recovery Linacs (ERLs). Strongly higher order mode (HOM) damped multicell 1.3 GHz cavities are required for the main linac. The cavity under study is an integrated design of the Cornell base cell with JLab HOM waveguide couplers. Modifications to the end group design have also been pursued, including the substitution of one waveguide by a HZB-modified TTF-III power coupler. In this talk the progress in HOM calculations to avoid beam-breakup instabilities for the favored cavity structure will be presented.
HZB, Berlin, Germany
LANL, Los Alamos, New Mexico, USA
LBNL, Berkeley, California, USA
While there is wisdom in the old adage "the two constants in life are death and taxes," there are unavoidable truths facing modern experimental and computational science. First is the growing "impedence mismatch" between our ability to collect and generate data, and our ability to store, manage, and gain understanding from it. The second is the fact that we cannot continue to rely on the same software technologies that have worked well for the past couple of decades for data management, analysis, and visualization. A third is that these complementary activities must be considered in a holistic, rather than balkanized way. The inseperable interplay between data management, analysis, visualization, and high performance computational infrastructure, are best viewed through the lens of case studies from multiple scientific domains, where teams of computer and accelerator scientists combine forces to tackle challenging data understanding problems.