Paper  Title  Page 

WEAAC2  Simulation of Baseband BTFs Using a Particleincell Code  121 


A simulation model for transverse bunched beam transfer functions (BTFs) at the base harmonic is presented. It is based on a code including different machine effects, most notably transverse space charge using a twodimensional (2D) Poisson solver. A simplified model for the simulation of the strongstrong beambeam effect was implemented using either 2D field data or analytic expressions under the assumption of Gaussian beams for the beambeam interaction. The validity of the BTF model is verified based on the comparison of BTF and Schottky spectra features with analytic expectations from literature. The simulation model is then applied to the RHIC proton lattice. A linear transfer map is used between interaction points. BTFs including the beambeam effect are simulated. Measurements are compared to simulation results at machine conditions.  
Slides WEAAC2 [2.829 MB]  
WEACC2  Space Charge Effects and Focusing Methods for Laser Accelerated Ion Beams  184 


Funding: GSI Helmholtzzentrum für Schwerionenforschung Planckstr. 1 D64291 Darmstadt We employ the 3D PIC simulation code VORPAL to study the transport of laser accelerated proton beams in the framework of the LIGHT project at GSI. Initially the beam is assumed to be neutralized by comoving electrons. For different initial beam distribution models we study the effect of space charge after the electrons have been removed. The results of the simulations are compared to an envelope model. We derive conditions in terms of the beam parameters and the distance from the production target for a safe removal of the electrons. As an option for the controlled deneutralization of the beam a thin metallic foil is studied. Besides space charge, we also account for the effect of secondary electrons generated from the foil. 

Slides WEACC2 [0.993 MB]  
THP02  Beam Dynamics Simulations Using GPUs  227 


PATRIC is a particle tracking code used at GSI to study collective effects in the FAIR synchrotrons. Due to the need for calculationintense simulations, parallel programming methods are being explored to optimize calculation performance. Presently the tracking part of the code is parallelized using MPI, where each node represents one slice of the particles that travel through the accelerator. In this contribution different strategies will be presented to additionally employ GPUs in PATRIC and exploit their support for data parallelism without major code modifications to the original tracking code. Some consequences of using only singleprecision in beam dynamics simulations will be discussed.  
FRSAI3  PIC Simulations of Laser Ion Acceleration via TNSA  290 


The laser acceleration of protons via the TNSA (Target Normal Sheath Acceleration) mechanism from a thin metal foil (few micrometer) interacting with intense and short (several 100 fs) laser pulse is investigated by using 1D and 2D particleincell electromagnetic VORPAL [1] simulations. The protons originate from the very thin hydrogenrich contamination layer on the target rear surface. In the 1D view we have found that two models well describe the longitudinal acceleration in the two extreme cases: quasistatic acceleration [2] for monolayers and isothermal plasma expansion [3] for thick layers. The grid heating, which is the most important issue in 2D simulations, and its effect on the proton acceleration is discussed. The required numerical parameters and boundary conditions for stable and reliable 2D simulations are also presented.
[1] http://www.txcorp.com/products/VORPAL/ [2] M. Passoni et al., Phys Rev E 69, 026411 (2004) [3] P. Mora, Phys. Rev. Lett., 90, 185002 (2003) 

Slides FRSAI3 [4.325 MB]  
MOSCC2  Simulation of Space Effects During Multiturn Injection into the GSI SIS18 Synchrotron  37 


The optimization of the Multiturn Injection (MTI) from the UNILAC into the SIS18 is crucial in order to reach the FAIR beam intensities required for heavy ions. In order to achieve the design intensities, the efficiency of the multiturn injection from the UNILAC has to be optimized for high beam currents. We developed a simulation model for the MTI including the closed orbit bump, lattice errors, the parameters of the injected UNILAC beam, the position of the septum and other aperture limiting components, and finally the space charge force and other highintensity effects. The model is also used to estimate the required proton and heavyion beam emittances from the UNILAC and from the projected plinac. For the accurate prediction of the MTI efficiency a careful validation of the simulation model is necessary. We will present first results of the comparison between experiments and simulation for low and high uranium beam currents.  
Slides MOSCC2 [2.511 MB]  
TUAAI3 
Simulation of Transverse Coherent Effects in Intense Ion Bunches  


The transverse stability thresholds for intense ion bunches in the FAIR synchrotrons as well as in other injector rings are determined by the interplay of space charge and transverse impedances. Also below the stability threshold space charge causes a strong modification of the headtail modes, with implications for the interpretation of beam signals from Schottky probes and BTF measurements. In order to predict stability thresholds and signals from stable bunches the simulations should be able to account for the 3D selfconsistent space charge field. Furthermore the accurate matching of the longitudinal particle distribution to different rf bucket forms is important in order to correctly resolve the headtail mode spectrum. Results obtained with the code PATRIC for the FAIR synchrotron will be presented. Some analytic solutions available for code validation are pointed out.  
WESCI2  Numerical Calculation of Beam Coupling Impedances in the Frequency Domain using FIT  193 


The transverse impedance of kicker magnets is considered to be one of the main beam instability sources in the projected SIS100 at FAIR and also in the SPS at CERN. The longitudinal impedance can contribute to the heat load, which is especially a concern in the cold sections of SIS100 and LHC. In the high frequency range, commercially available time domain codes like CST Particle Studio® serve to calculate the impedance but they become inapplicable at medium and low frequencies which become more important for larger size synchrotrons. We present the ongoing work of developing a Finite Integration (FIT) solver in frequency domain which is based on the Parallel and Extensible Toolkit for Scientific computing (PETSc) framework in C++. Pre and postprocessing are done in MATLAB®. Infinite beam pipe boundary conditions are used. The code is applied to an inductive insert used to compensate the longitudinal space charge impedance in low energy machines. Another application focuses on the impedance contribution of a ferrite kicker with inductively coupled pulse forming network (PFN) and frequency dependent complex material permeability.  
Slides WESCI2 [3.468 MB]  