MOAAI3
Northern Illinois University, DeKalb, Illinois, USA
Transfer maps methods and and associated analysis tools, such as the normal form method, are well-known in the single particle beam dynamics realm. When space charge effects are not negligible, it becomes more difficult to include them in a self-consistent map picture. In this talk, we present a basis-function method that relies on particle distribution moments and differential algebraic integration techniques that allow, for the first time, the extraction of self-consistent high order Taylor maps of space charge dominated beam dynamics with almost the same ease as in the single particle case.
MOABC2
TUE, Eindhoven, The Netherlands
Pulsar Physics, Eindhoven, The Netherlands
UMAN, Manchester, United Kingdom
University of Huddersfield, Huddersfield, United Kingdom
We present large scale simulations of the LHC collimation system using the MERLIN code for calculations of loss maps, currently using up to 1.5·109 halo particles. In the dispersion suppressors following the collimation regions, protons that have undergone diffractive interactions can be lost into the cold magnets. This causes radiation damage and could possibly cause a magnet quench in the future with higher stored beam energies. In order to correctly simulate the loss rates in these regions, a high statistics physics simulation must be created that includes both accurate beam physics, and an accurate description of the scattering of a 7 TeV proton in bulk materials. The current version includes the ability to simulate new possible materials for upgraded collimators, and advances to beam-collimator interactions, including proton-nucleus interactions using the Donnachie-Landshoff Regge-Pomeron scattering model. Magnet alignment and field errors are included, in addition to collimator jaw alignment errors, and their effects on the beam losses are systematically estimated. Collimator wakefield simulations are now fully parallel via MPI, and many other speed enhancements have been made.
MOACC1
KIT, Karlsruhe, Germany
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
At the synchrotron radiation facility at DESY transversal tune spectra have been observed which are characteristic for an interaction of the positron beam with possible electron clouds in the ring. The filling patterns at which this incoherent tune shifts happen are favourable to the growth of the electron density, i.e. long bunch trains with short intra-bunch distances or filling with short trains but also short distances between the trains. Eventually the vertical emittance growth with the originally designed equidistant filling (with 8 or 16 ns bunch spacing) has been avoided by fillings with shorter trains and longer gaps between the trains by still achieving the designed beam current of 100 mA. In this paper we examine the positron bunch stability of PETRA III for certain e-cloud densities and bunch parameters. A PIC simulation of the interaction of the bunch with an e-cloud yields the wake kick on the tail particles for an offset in the transverse centroid position of the head parts. With such a pre-computed wake matrix, we investigate the stability of a single bunch by tracking it through the linear optics of the ring while at each turn applying the kick from the e-cloud.
FZJ, Jülich, Germany
St. Petersburg State University, St. Petersburg, Russia
MSU, East Lansing, Michigan, USA
TUADC2
Tech-X, Boulder, Colorado, USA
DESY, Hamburg, Germany
KEK, Ibaraki, Japan
Over the past several years, Forest has added spin motion and related capabilities to PTC [1]. The capabilities include, via FPP [2], the computation of a spin normal form. This normal form, and the associated normalising maps for orbit and spin, provide us with immediate access to important quantities, including the invariant spin field and resonance strengths. The algorithms in PTC/FPP thus represent an alternative approach to computing significant quantities for the analysis of spin dynamics in particle accelerators. We describe the PTC algorithm, note similarities with the case of the orbital normal form, and give illustrative examples. In particular, we apply PTC to the well-understood COSY lattice, and we compare the results computed by PTC with those computed by the well-tested code EpsSLICK [3].
[1] E. Forest, F. Schmidt, and E. McIntosh, KEK Report 2002-3.
[2] E. Forest, Y. Nogiwa, and F. Schmidt, ICAP2006, p. 191-193.
[3] D. Barber, DESY Report, DESY-2009-15.
KU Leuven, Kortrijk, Belgium
TEMF, TU Darmstadt, Darmstadt, Germany
Developing beam dynamics simulation tools using the moment method has advantages in terms of precision and efficiency when interests lie in average or rms dimensions of the beam, projected emittances or total energy. The moment method implemented in the V-Code solves the Vlasov equation by time integration, from an initial particle distribution represented by a discrete set of characteristic moments, accounting for all acting internal and external forces along the particle's path. The moment method delivers highly accurate beam dynamics results within a very small CPU time. This article proposes, illustrates and validates a new beam line element for a radiofrequency quadrupole (RFQ) for insertion in the V-Code. The focus will be on the RFQ cell structure, the electric field distribution and the insertion of the field distribution in the moment code.
CERN, Geneva, Switzerland
Naples University Federico II, Science and Technology Pole, Napoli, Italy
CERN, Geneva, Switzerland
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.
HZB, Berlin, Germany
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
Energy Recovery Linacs (ERLs) are the most promising candidates for next-generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Obviously, the vacuum chamber has to be cleared out of ions but as the potential of the electron beam attracts the ions, it is not enough to install vacuum pumps. One measure for ion clearing are gaps in the bunch train long enough that the ions have time to escape the force of the bunch potential. In this paper, we present numerical studies of the behavior of an ion cloud that interacts with a bunch train. Especially, we consider different distributions for the particles in the bunch, different fill patterns and several mixtures of ions in the residual gas. The simulations are performed with the package MOEVE PIC Tracking. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPro.
WEP03
KIRAMS, Seoul, Republic of Korea
WEP04
KIRAMS, Seoul, Republic of Korea
St. Petersburg State University, St. Petersburg, Russia
GSI, Darmstadt, Germany
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 co-moving 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 de-neutralization 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.
St. Petersburg State University, St. Petersburg, Russia
CERN, Geneva, Switzerland
GSI, Darmstadt, Germany
THP03
Tech-X, Boulder, Colorado, USA
DESY, Hamburg, Germany
BNL, Upton, Long Island, New York, USA
Graphics processing units (GPUs) have now become powerful tools for scientific computation. Here we present our work on using GPUs to speed the tracking of both orbital and spin degrees of freedom in particle accelerators. This work includes the development of new spin integrators that are both fast and accurate. We have also developed an integrated set of tools for analysing the results. To demonstrate the utility of these new tools, we use them to study the spin dynamics of protons in the Relativistic Heavy Ion Collider at Brookhaven National Lab.
THSCI1
MSU, East Lansing, Michigan, USA
A common task in the design and analysis of an accelerator is the study of the transfer map of the system. Of particular interest is the estimation of the region of stability of a given system. Typically, this is done using symplectic particle tracking and visual analysis of the resulting Poincare maps for signatures of chaoticity and island structures near high-period fixed points. We describe a method to compute rigorous enclosures of all periodic points of a given order in a given map based on Taylor Model methods. We then apply this algorithm to a real world transfer map of the Tevatron accelerator to rigorously identify islands and resonances in its transfer map. This mathematically rigorous method to locate resonances in the transfer map automatically yields all regions where resonances up to a certain order appear. The island structure exhibited by the map in those regions is then studied further by computing the invariant manifolds associated with the hyperbolic periodic points of the map. This manifold structure can provide further insight into the dynamics of the map, including the emergence of chaotic motion at the appearance of crossings of the manifolds.
THADI1
DESY, Hamburg, Germany
THADC2
MSU, East Lansing, Michigan, USA
Recent interest electric dipole moments of hadrons and light nuclei necessitates the design of storage ring designs relying on electrostatic elements for deflection and focusing. Since the effects of interest are exceedingly small and difficult to extract from the dynamics, unusually high precision in the understanding of the linear and nonlinear optics is required. This leads to the need of precise treatment of a various effects that are often of subdued importance, including the detailed shape of fringe fields and their influence on steering, spin flip devices, and rf cavities out of synch with the frequency of the ring. In all studies, it is important to perform symplectic tracking for the full spin-orbit dynamics. At the same time it is necessary to preserve the particle’s energy during transversal of electric potentials, errors in which are similarly detrimental as errors in symplecticity. Unfortunately it is known that schemes to preserve symplecticity do not simultaneously preserve energy and vice versa. We present some hybrid approaches based on high-order maps that minimize the violations of either invariant while minimally impacting spin-orbit motion.
THADC3
MSU, East Lansing, Michigan, USA
Fermilab, Batavia, USA
FFAGs are being considered for various new classes of accelerators, including proton drivers for muon colliders and neutrino factories, for accelerator driven subcritical reactors, and for medical applications. Their key advantages are compactness, CW operation and large acceptance. However, due to the complicated field arrangements, beam dynamics simulations are challenging for conventional simulation codes. Among various levels of sophistication of dealing with beam elements, one of the most advanced modes of the code COSY INFINITY computes the 3D field distributions along the trajectory of the particles, not only at the point of interest but also in the neighborhood with functional dependencies, using DA PDE solvers based on Differential Algebraic techniques. The scheme allows the code developer and user to describe rather complicated field arrangements with rather limited effort. Of particular advantage is the seamless integration with map-based symplectic tracking schemes. The methods are illustrated in design studies of FFAGs for various different machine types, including both conventional strong focusing and continuously varying combined function setups.