Beam Dynamics and Electromagnetic Fields




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НазваниеBeam Dynamics and Electromagnetic Fields
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Дата конвертации20.04.2013
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Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


622 - A Method for Numerical Solution 2-D Poisson's Equation with Image Fields
V. Kapin, NIRS, Chiba City

Simulation of high intensity accelerators leads to the calculation of space charge forces between macroparticles in the presence of acceleration chamber walls. To calculate space-charge forces, one solves the Poisson's equation in 3-D. For an accelerator with long bunches, the 3-D problem is usually reduced to 2-D, because the transverse motion can be decoupled from the longitudinal due to very different characteristic times. The simulation of large macroparticle ensembles requires rapid evaluations of space-charge forces. Fast field solvers are usually based on Fourier-transform methods, but they are not applicable for arbitrary geometries of walls. For arbitrary walls, the solution for Poisson's equation can be derived using a Green function, which is numerically calculated on discrete mesh points. For simple wall geometries, e.g., circle and ellipse, it can be expressed analytically. Usually, such technique results in slow solvers. We discuss here a method, which combines a Green function technique and Fast-Fourier transformation solver. In the first step, the Green function technique is used for arbitrary walls to calculate potentials on an intermediate rectangular boundary, which includes all macroparticles. In the second step, Fast-Fourier transformation solver calculates potentials inside this rectangular boundary with given potentials. Preliminary numerical results will be reported.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


210 - Impact of the RF-Gun Power Coupler on Beam Dynamics
M. Krassilnikov, R. Cee, T. Weiland, TU-Darmstadt, Darmstadt

A production of high brightness electron beams is necessary for FEL operation. Since the beam quality degrades as the beam propagates along the beam line, every perturbation factor has to be studied. The electron beam dynamics in the TESLA Test Facility (TTF DESY) rf-gun has been investigated with the on-line simulation tool V-Code. While some of the rf-gun misalignments can be corrected by an earlier developed alignment procedure, the aside power coupler causes a field asymmetry resulting in unavoidable steering forces. The dependence of the accelerating mode offset on the longitudinal coordinate, calculated with CST Microwave Studio, has been implemented in the V-Code. Assuming a possible laser beam offset on the cathode additionally to the given rf field asymmetry one can explain the dependence of the electron beam offset measured by the first beam position monitor (BPM1) on rf phase. The measured data as well as simulation results are presented.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


1217 - Single-Bunch Instability of Positron Beams in a Rare Electron Plasma
K. Lotov, BINP, Novosibirsk; G. Stupakov, SLAC, Stanford

Single-bunch instability of a short and dense positron beam in a photo-electron plasma is studied numerically with code LCODE. The code was originally developed for studies of plasma wakefield acceleration. It is two-dimensional and fully relativistic, with both the beam and electrons modelled by macro-particles. The instability is shown to affect the rear part of the beam, right after the arrival of nearby electrons to the axis. As the result, the emittans of the whole beam grows exponentially. The instability can be stabilized by an external longitudinal magnetic field. The field does not itself stabilize the instability, but prevents the electrons from going to axis once they were thrown to the wall by the previous bunch.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


1459 - Application of UAL-Based Correction Schemes to the SNS Accumulator Ring*
N. Malitsky, A.V. Fedotov, I. Papaphilippou, J. Wei, BNL, Upton, Long Island, New York

The SNS ring correction schemes were tested using the Unified Accelerator Libraries (UAL). The capabilities of some already existing algorithms, such as tune and chromaticity fitting , orbit and coupling correction [1], were applied to beam dynamics studies. In addition, the option of beam-based correction schemes was investigated and compared with the purely analytic approach.

* SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

[1] R.Talman. A Universal Algorithm for Accelerator Correction. AIP 255, 1992.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


746 - Simulations of Transient Phenomena in Thermionic RF Guns
V. Mytrochenko, V. Kushnir, A. Opanasenko, KIPT, Kharkov

The report is dedicated to simulation of transient phenomena in resonant systems of thermionic RF guns caused by beam loading effect. The technique of the PARMELA code using for evaluation of a resonant system excitation by electron bunches is described. The results of transient phenomena simulation in some RF guns are given as examples.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


844 - Bunching of Weakly Relativistic Intense Electron Beam
V. Mytrochenko, M. Ayzatsky, V. Kushnir, A. Opanasenko, KIPT, Kharkov

Problems connected with strong influence of space charge forces on bunch formation arise under development of microwave sources and linac injectors with comparatively low energy of electron beam (when energy of particles is several tens of keV). Results of intense electron beam dynamics simulation in bunching systems are presented in this report. The main attention was given to the bunching process in resonant systems based on a coupled cavity chain.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


1458 - Simulations of Flip-Flop Behavior of Colliding Beams
I. Nesterenko, P. Ivanov, D. Shatilov, E. Simonov, BINP, Novosibirsk

In this paper computer simulations of flip-flop behavior of transverse sizes in framework of strong-strong model for e+e- colliding beams are presented. Features of this type instability for both flat and round beam concepts are discussed.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


460 - Twisted Radial Sinusoidal Modulated Wiggler
V. Niculescu, INFLPR, Bucharest, sect. VI; V. Babin, INOE2000, Bucharest-com. Magurele; M.R. Leonovici, Univ.Buc., Bucharest-com. Magurele

For free electron laser wigglers a new theoretical model was presented. The wiggler is a stack of radial sinusoidal modulated rings of wires which in xy plane are described by the following type of equations : x=(R+pRsin(k*teta))*cos(teta),y=(R+pRsin(k*teta))*sin(teta),z=cst.; k=2,3,4,...;p=m/n,m

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


1582 - Beam Dynamics Optimization in RFQ Structures
A. Ovsyannikov, I. Antropov, D. Ovsyannikov, SPbSU, St.Petersburg; B. Bondarev, A. Durkin, MRI, Moscow

In this paper mathematical methods of optimization of beam dynamics in RFQ structures are developed. Different mathematical optimization models of charged particles dynamics are suggested. BDO-RFQ code that is created on the base of these methods and models allows modeling and optimization of beam dynamics at various stages of investigation. In particular, longitudinal and transverse motions can be considered separately. For the estimations of beam dynamics the system of functionals is introduced. It allows conducting multi-goals optimization with taking into account various limitations for RFQ structure.

Type of presentation requested : Poster

Speaker :
Dr. A. Ovsyannikov

Classification : [D05] Code Developments and Simulation Techniques


355 - Beam Loading the Standing Wave Injector on the Base of Evanescent Wave
S. Perezhogin, M. Ayzatsky, K. Kramarenko, KIPT, Kharkov

Standing wave injectors on the base of evanescent waves are considered. Injectors consist of the fragments of the cylindrical discloaded waveguide and biperiodic cylindrical discloaded waveguide. The parameters of the systems are selected in such a way, that at the working frequency the resonant oscillation in the injector corresponds to the evanescent wave of the boundless periodic structure. It gives possibility to create in the injector the increasing amplitude distribution, which improves the bunching process at the initial stage of acceleration. The simulation of the beam dynamics is carried out with taking into account the beam loading.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


632 - Symplectic Integrator for Particle Tracking in Complex Magnetic Field
P. Piminov, E. Levichev, BINP, Novosibirsk

High field wigglers for synchrotron radiation production have usually rather complex distribution of magnetic field, and particle motion through it can hardly be treated analytically. This paper concerns a simple and reliable receipt for a symplectic algorithm to track a particle through such fields. Input data for numeric integration are taken directly from results of magnetic mapping or simulation of 2D field values array. A 3-pole 7 T superconducting wiggler is considered as an example.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


1173 - A Fast 3D Multigrid Based Space-Charge Routine in the GPT Code*
G. Pöplau, U. van Rienen, Universität Rostock, Rostock; M. de Loos, B. van der Geer, Pulsar Physics, Soest

Fast calculation of 3D non-linear space-charge fields is essential for the simulation of high-brightness charged particle beams. We report on our development of a new 3D space-charge model that scale nearly with the number of particles in terms of CPU time. The model is based on a multigrid Poisson solver used to solve the electrostatic fields in the rest frame of the bunch. The multigrid Poisson solver is adapted to the non-equidistant rectangular grids generated in order to get a good approximation of the particle distribution while keeping the number of grid points as small as possible. Lorentz transformations are applied for the transformation from lab- to rest-frame and vice-versa. The new algorithm is implemented as a custom element in the General Particle Tracer (GPT) code. Numerical results will be presented.

*supported by a research grant from DESY, Hamburg

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


85 - A New Technique to Compute Long-Range Wakefields in Accelerating Structures
J.-Y. Raguin, J. Prochnow, W. Wuensch, CERN, Geneva

A new technique is proposed to compute the long-range wakefields based on a scattering matrix formalism which relies heavily on post-processed data from the commercial finite-element code HFSS. To illustrate the accuracy and the speed of this technique, computations of the long-range wakefields of conventional constant-impedance structures and of structures damped with waveguides are given. The efficiency and accuracy of the technique is achieved because the characteristics of periodic structures can be computed using single-cell data. Damping and synchronism effects are determined from such a computation. The results are compared with a direct-time domain approach.

Type of presentation requested : Poster

Speaker :
Dr. J.-Y. Raguin

Classification : [D05] Code Developments and Simulation Techniques


724 - MAD-X, an Upgrade from MAD8
F. Schmidt, H. Grote, CERN, Geneva

The development of MAD8 has been suspended for many years. At the start of 2001

it was decided to revive it and put it into a more maintainable form since it is needed for the LHC during design and operation. In particular, the home grown dynamic data management in Fortran77 limits further extensions, and is not guaranteed to survive for another ten years. In fact, MAD-X has been originally planned to be a copy of MAD8 with a more modern data management. The data structures that hold the information about the accelerator, and the interfaces to the modules are written in C which provides the dynamic data structures needed. Contrary to MAD8, the MAD-X modules are designed as truly independent entities; they will be much simpler and therefore better maintainable. It was also thought important to spread the responsibility for the various MAD-X modules among several accelerator physicists. Lastly, an upgrade of MAD-X is being planned to improve the physics models and to include map related tools using Etienne Forest's PTC code.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


391 - FEL Photoinjector Simulation Studies by Combining MAFIA TS2 and ASTRA
S. Setzer, R. Cee, M. Krassilnikov, T. Weiland, TU-Darmstadt, Darmstadt

For the successful FEL operation a high brightness low emittance beam is of crucial importance. For a detailed investigation of the emittance development the simulations should not be restricted to the RF-Gun only. That is why the two simulation codes MAFIA TS2 and ASTRA have been combined in order to make use of their individual advantages. The PIC code MAFIA TS2 is used for detailed modelling of the space charge effects inside the RF-Gun. By using a data interface the beam dynamics downstreams the RF-Gun is simulated by ASTRA which is capable of simulating long accelerator structures efficiently. In this paper we discuss the advantages and limitiations of both simulation approaches. Additionally the results of combined simulations using both codes are presented.

Work supported in part by DESY Hamburg.

Type of presentation requested : Poster

Classification : [D05] Code Developments and Simulation Techniques


1224 - New 2D Real-time Radiation Field Simulator
T. Shintake, KEK, Ibaraki-ken

Real time computer simulator for 2D radiation field pattern has been developed. Graphic shows radiation from a moving charge in free space. Instead of processing time-consuming integration of the retarded potential, it simply tracks the flow of "information points" emitted from moving charge. The light aberration is correctly implemented to ensure relativistic conversion. Pre-coded models are synchrotron radiation, dipole, undulator radiations, as well as radiations from your mouse movement.
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