ANL, Argonne
We are developing highly scalable solvers for space charge dominated beams based on both Particle-In-Cell (PIC) and direct Vlasov models. For the PIC model, particles are distributed evenly on different processors and space charge effect has been counted by solving Poisson's equation on a finite mesh. Several Poisson solvers have been developed using Fourier, Spectral Element (SEM) and Wavelet methods. Domain decomposition (DD) has been used to parallelize these solvers and all these solvers have been implemented into the PTRACK code. PTRACK is now widely used for large scale beam dynamics simulations in linear accelerators. For the Vlasov model, Semi-Lagrangian method and time splitting scheme have been employed to solve Vlasov equation directly in 1P1V and 2P2V phase spaces. 1D and 2D Poisson solvers have been developed with SEM. Similarly, DD has been used for parallelization of Poisson and Vlasov solvers. New efforts on developing Vlasov and Poisson solvers on unstructured mesh will also be reported.
BNL, Upton, Long Island, New York
KVI, Groningen
CLASSE, Ithaca, New York
In the proposed electric dipole moment (EDM) experiment, with an estimated spin coherence time of 1000 s, the spin precession due to an EDM of 10-29 e.cm will produce a change in the vertical spin component of approximately 10 μrad during the storage time. Such high sensitivity needs an extremely high accurate and reliable simulation environment of the beam and spin behavior during the storage time. Therefore, several spin-related accelerator programs have been considered and investigated. The paper surveys the computational algorithms of these approaches and provides their comprehensive analysis from multiple perspectives: accuracy, performance, extensibility, and scope of potential applications.
IHEP Beijing, Beijing
Electron Cloud Instability (ECI) may take place in any positively charged particle circular accelerator especially in positron and proton storage ring. This instability has been confirmed to be a serious restriction to the beam stabilities. The physical model on the formation of electron cloud in various kinds of magnetic fields was introduced in the first section of the paper. The transverse and longitudinal wake field model to present the interaction between electron cloud and beam were introduced in another section of the paper. As an example, in positron storage of BEPCII and RCS of CSNS, the densities of electron cloud and beam instabilities caused by the accumulated electrons were simulated.
TRIUMF, Vancouver
The simulation toolkit GEANT4 has been used to create high-level tools for specific user groups, such as SPENVIS in space physics and GATE in medical imaging. In Accelerator Physics, comparable efforts are being devoted to develop general-purpose programs for simulating beamlines and accelerators, allowing access to Geant4's facilities for 3D geometry, tracking, and interactions in matter without the need for specialised programming techniques. In this study we investigate the use of two high-level tools based on Geant4, G4BEAMLINE and BDSIM, to model a 65-meter beam line supplying protons from the TRIUMF cyclotron to the ISAC RIB facility. We outline the rather different approaches to defining the beamline geometry (including cyclotron extraction foil and exit region) in each code. Their diagnostic and visualisation features are also compared. Due to its ability to model some important aspects such as rectangular dipoles and magnetic fringe fields, G4beamline was utilized for a series of simulations presented here, investigating the distribution of losses in the beamline, the role of scattering in the cyclotron extraction foil, and the sensitivity of losses to tuning parameters.
GSI, Darmstadt
ITEP, Moscow
IAP, Frankfurt am Main
During the last year several numerical investigations have been started at GSI in order to improve the performance of the linear accelerator facility. The main activities regard the upgrade of the high current UNILAC accelerator including the severe upgrade of the HSI injector, the HITRAP decelerator and, in the frame of the future FAIR project, the development of the new dedicated proton linac. End to end beam dynamics simulations are a powerful tool concerning the machine design, commissioning and optimization. Particle distributions, generated from beam emittance measurements, are transferred through the whole chain of the accelerating structures and beam transport lines. Detailed calculations of the space charge effects as well as external and measured mapping of the structures electromagnetic fields are used to provide the most reliable results. The paper presents a general overview of all activities including a comparison with experimental results.
BNL, Upton, Long Island, New York
In order to preserve polarization during polarized proton operation for RHIC, two partial Siberian Snakes are employed in the AGS, where a number of strong spin depolarization resonances must be crossed. These Snakes cause a significant distortion to the injection lattice of the AGS and must be included in the on-line model. In this report we discuss the problem of modeling Snakes as optical elements, particularly as madx elements, and present results comparing measurements to the AGS on-line model.
Fermilab, Batavia
The beam-beam simulation code (BBSIMC) is a incoherent multiparticle tracking code for modeling the nonlinear effects arising from beam-beam interactions and the compensation of them using an electromagnetic lens. It implements short range transverse and longitudinal wakefield, dipole noise to mimic emittance growth from gas scattering, beam transfer function, and wire compensation models. In this paper, we report on recent improvements of the BBSIMC including a beam-beam compensation model using a low energy electron beam and an interpolation scheme of beam-beam forces. Some applications are presented for the Relativistic Heavy Ion Collider (RHIC) electron lens.
Fermilab, Batavia
The Recycler is a fixed 8 GeV kinetic energy storage ring using permanent gradient magnets. A phase trombone straight section is used to control the tunes. For ProjectX , the H-particle extracted from the Linac will be striped and painted in the Recycler Ring and then the protons will be extracted into the Main injector. A long drifting space is needed to accommodate the injection chicane with stripping foils. In this paper, the existing FODO lattice in rr10 straight section being converted into doublet will be described. Due to this change, the phase trombone straight section has to be modified to bring the tunes to the nominal working point. On the other hand, a toy lattice of recycler ring is designed to simulate the end-shim effects of each permanent gradient magnet to add the flexibility to handle the tune shift to the lattice during the operation of 1.6·1014 with KV distribution of the proton beam to give ~0.05 of space charge tune shift . The comparison or the combinations of the two modification ways for the Recycler ring lattice will be presented also in this paper.