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SciDAC advances in beam dynamics simulation: from light sources to colliders

Description: In this paper, we report on progress that has been made in beam dynamics simulation, from light sources to colliders, during the first year of SciDAC-II accelerator project,"Community Petascale Project for Accelerator Science and Simulation (ComPASS)." Several parallel computational tools for beam dynamics simulation will be described. A number of applications in current and future accelerator facilities, e.g., LCLS, RHIC, Tevatron, LHC, ELIC, are presented.
Date: June 16, 2008
Creator: Qiang, Ji; Qiang, J.; Borland, M.; Kabel, A.; Li, R.; Ryne, R. et al.
Partner: UNT Libraries Government Documents Department

Solution of K-V envelope equations

Description: The envelope equations for a KV beam with space charge have been analyzed systematically by an e expansion followed by integrations. The focusing profile as a function of axial length is assumed to be symmetric but otherwise arbitrary. Given the bean current, emittance, and peak focusing field, we find the envelopes a(s) and b(s) and obtain <a>, a{sub max}, {sigma}, and {sigma}{sub 0}. Explicit results are presented for various truncations of the expansion. The zeroth order results correspond to those from the well-known smooth approximation; the same convenient format is retained for the higher order cases. The first order results, involving single correction terms, give 3--10 times better accuracy and are good to {approximately}1% at {sigma}{sub 0} = 70{degree}. Third order gives a factor of 10--30 improvement over the smooth approximation and derived quantities accurate to {approximately}1% at {sigma}{sub 0} = 112 {degree}. The first order expressions are convenient design tools. They lend themselves to variable energy problems and have been applied to the design, construction, and testing of ESQ accelerators at LBL.
Date: April 1, 1995
Creator: Anderson, O.A.
Partner: UNT Libraries Government Documents Department

Advanced Computing Tools and Models for Accelerator Physics

Description: This paper is based on a transcript of my EPAC'08 presentation on advanced computing tools for accelerator physics. Following an introduction I present several examples, provide a history of the development of beam dynamics capabilities, and conclude with thoughts on the future of large scale computing in accelerator physics.
Date: June 11, 2008
Creator: Ryne, Robert & Ryne, Robert D.
Partner: UNT Libraries Government Documents Department

Electron-Cloud Build-Up: Theory and Data

Description: We present a broad-brush survey of the phenomenology, history and importance of the electron-cloud effect (ECE). We briefly discuss the simulation techniques used to quantify the electron-cloud (EC) dynamics. Finally, we present in more detail an effective theory to describe the EC density build-up in terms of a few effective parameters. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC.
Date: October 8, 2010
Creator: Furman, M. A.
Partner: UNT Libraries Government Documents Department


Description: The SNS Ring off-line parallel simulation environment based on the Unified Accelerator Libraries (UAL) has en implemented and used for extensive full-scale beam dynamics studies arising in high-intensity ring. The paper describes the structure of this environment and its application to various high-intensity topics and diagnostics modeling.
Date: April 8, 2002
Partner: UNT Libraries Government Documents Department

Brickwall effect

Description: A quantitative account of the brickwall effect is given. By combining the theory of the resistive wall instability- with the theory of a nonuniform incoherent tune shift, it is shown how the brickwall effect manifests itself as a limit on the current tune density (current/tune spread) at some critical stack width. A description of the effect in the CERN ISR is given. It is also shown, by an example, how the limiting current condition can be used in a certain class of storage ring design. (auth)
Date: September 18, 1973
Creator: Month, M.
Partner: UNT Libraries Government Documents Department

Advanced beam-dynamics simulation tools for the RIA driver linac,Part I: Low energy beam transport and radiofrequency quadrupole

Description: Advanced Beam-Dynamics Simulation Tools for the RIA Driver Linac; Low Energy Beam Transport and Radiofrequency Quadrupole.
Date: August 26, 2003
Creator: Wangler, Thomas P.; Crandall, Kenneth R.; Garnett, Robert W.; Gorelov, Dmitry; Ostroumov, Petr; Qiang, Ji et al.
Partner: UNT Libraries Government Documents Department

Simulation results for the electron-cloud at the PSR

Description: We present a first set of computer simulations for the main features of the electron cloud at the Proton Storage Ring (PSR), particularly its energy spectrum. We compare our results with recent measurements, which have been obtained by means of dedicated probes.
Date: June 26, 2001
Creator: Furman, M.A. & Pivi, M.
Partner: UNT Libraries Government Documents Department

Some results of the advanced photon source beam lifetime studies

Description: Total beam lifetime consists of two components: the residual-gas-scattering lifetime and Touschek lifetime. The residual-gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. Touschek scattering involves scattering of particles within the bunch. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual-gas-scattering lifetime component. Experience gained from computing the beam lifetime in the Advanced Photon Source (APS) storage ring shows that the electron scattering should not be neglected, particularly the inelastic contribution. Given the measured quantities from the APS storage ring, one can compare theoretical predictions with experimental results. Uncertainties in calculating the various contributions to lifetime will be discussed.
Date: June 1, 1997
Creator: Bizek, H.M.
Partner: UNT Libraries Government Documents Department

Transmission line analysis of beam deflection in a BPM stripline kicker

Description: In the usual treatment of impedances of beamline structures the electromagnetic response is computed under the assumption that the source charge trajectory is parallel to the propagation axis and is unaffected by the wake of the structure. For high energy beams of relatively low current this is generally a valid assumption. Under certain conditions the assumption of a parallel source charge trajectory is no longer valid and the effects of the changing trajectory must be included in the analysis. Here the usual transmission line analysis that has been applied to BPM type transverse kickers is extended to include the self-consistent motion of the beam in the structure.
Date: May 1, 1997
Creator: Caporaso, G.J.; Chen, Yu Ju & Poole, B.
Partner: UNT Libraries Government Documents Department

Summary of the session on other effects

Description: The theme of this workshop is to discuss the effects of foreign particles on the native beam in a storage ring. This paper summarizes the session on effects not covered in sessions on fast ion instability, electron cloud instability, and cures. The topics discussed are the beam, the foreign particle, how are foreign particles trapped, and how do foreign particles and beam couple.
Date: July 1, 1997
Creator: Chao, A.
Partner: UNT Libraries Government Documents Department

Swamp plots for dynamic aperture studies of PEP-II lattices

Description: With a newly developed algorithm using resonance basis Lie generators and their evaluation with action-angle Poisson bracket maps (nPB tracking) the authors have been able to perform fast tracking for dynamic aperture studies of PEP-II lattices as well as incorporate lattice nonlinearities in beam-beam studies. They have been able to better understand the relationship between dynamic apertures and the tune shift and resonance coefficients in the generators of the one-turn maps. To obtain swamp plots (dynamic aperture vs. working point) of the PEP-II lattices, they first compute a one-turn resonance basis map for a nominal working point and then perform nPB tracking by switching the working point while holding fixed all other terms in the map. Results have been spot-checked by comparing with element-by-element tracking.
Date: June 1, 1995
Creator: Yan, Y.T.; Irwin, J.; Cai, Y.; Chen, T. & Ritson, D.
Partner: UNT Libraries Government Documents Department

Wake fields, potential well distortion and beam stability in the LER PEP-II

Description: Longitudinal and transverse wake fields are constructed for LER PEP-II. The effects of potential well distortion and the single bunch longitudinal stability are discussed for LER PEP-II storage ring. The coupled-bunch stability recalculated with the updated impedance.
Date: February 1, 1996
Creator: Heifets, S.A.
Partner: UNT Libraries Government Documents Department

Extensions of the longitudinal envelope equation

Description: Recently, longitudinal space charge effects have become of increased importance in a variety of dynamical situations. The CEBAF FEL injector beam dynamics shows large space-charge effects, even at 10 MeV ({gamma} {approx} 20). Space-charge dominated longitudinal motion has also been studied in the IUCF ion storage ring. Previously a longitudinal envelope equation with a self-consistent phase-space distribution has been developed, and has been of considerable use in analyzing the motion of these cases. Longitudinal motion in detailed agreement with this envelope equation has been observed at the U. of Maryland Laboratory for Plasma Research, and at the GSI electron cooling storage ring ESR, as well as at the IUCF. However, the initial presentation in ref. 4 used non-relativistic linear- accelerator bunching motion as a simplifying approximation in order to avoid inadvertent errors and minimize misprints, and must be adapted to include relativistic and/or synchrotron effects. In the present note we extend the envelope equation formulae to include relativistic, synchrotron, and acceleration effects, and define the various factors in the equations in explicit detail. The object is to obtain a set of debugged formulae for these extended cases, with all of the various factors defined explicitly, so that the formulae can be used as a reference without repetitive rederivations. The usual ambiguities over emittance definitions and units and {beta}, {gamma}, g factors should be resolved. The reader (or readers) is invited to discover any remaining errors, ambiguities or misprints for removal in the next edition. 12 refs.
Date: December 1, 1996
Creator: Neuffer, D.
Partner: UNT Libraries Government Documents Department

Coherent beam-beam effects, theory & observations

Description: Current theoretical understanding of the coherent beam-beam effect as well as its experimental observations are discussed: conditions under which the coherent beambeam modes may appear, possibility of their resonant interaction (coherent resonances), stability of beam-beam oscillations in the presence of external impedances. A special attention is given to the coherent beam-beam modes of finite length bunches: the synchro-betatron coupling is shown to provide reduction in the coherent tuneshift and--at the synchrotron tune values smaller than the beam-beam parameter--Landau damping by overlapping synchrotron satellites.
Date: July 16, 2003
Creator: Alexahin, Yuri I
Partner: UNT Libraries Government Documents Department

Coherent synchrotron radiation: Theory and experiments

Description: Our understanding of the generation of coherent synchrotron radiation in magnetic bending systems and its impact on beam dynamics has grown considerably over the past few years. The search for understanding has brought a number of surprises, all related to the complexity of the fully self-consistent problem. Herein I survey the associated phenomenology, theory, and experiments while emphasizing important subtleties that have recently been uncovered. I conclude by speculating on courses of future investigations that may prove fruitful.
Date: July 19, 2002
Creator: Bohn, Courtland L.
Partner: UNT Libraries Government Documents Department

Theory and suppression of multibunch beam breakup in linear colliders

Description: The authors recently developed an analytic theory of cumulative multibunch beam breakup that includes a linear variation of transverse focusing across the bunch train. The focusing variation saturates the exponential growth of the beam breakup and establishes an algebraic decay of the transverse bunch displacement versus bunch number. In this paper they illustrate how the focusing variation works to suppress multibunch beam breakup, as well as how the mechanism scales with accelerator and beam parameters.
Date: August 8, 2000
Creator: Ng, Courtlandt L. Bohn and King-Yuen
Partner: UNT Libraries Government Documents Department

Enhancements to the longitudinal dynamics code ESME

Description: ESME is a program developed at Fermilab for simulating both single particle and multi-particle dynamics in proton synchrotrons. The code has evolved incrementally for more than fifteen years, accumulating many useful features and some internal inconsistency in the process. In the latest revision (8.2), a significant effort has been made to eliminate inconsistency and ambiguity in the determination of phases for multiple RF systems. The use of frequency and phase curves is now more transparent. Other additions or improvements include additional features for time domain calculation, low noise distributions to extend multi-particle capability, run-time memory allocation and portable graphics. A Web page has been established to facilitate the distribution of the source code and documentation. Further information, bug reports and fixes will be made available through this resource.
Date: May 1, 1997
Creator: MacLachlan, J. & Ostiguy, J.F.
Partner: UNT Libraries Government Documents Department