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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


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

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


Description: An advantage of a proton Super-conducting Linac (SCL) is that RF cavities can be operated independently, allowing easier beam transport: and acceleration. But cavities are to be separated by drifts long enough to avoid they couple to each other. Moreover, cavities are placed in cryostats that include inactive insertions for cold-warm transitions; and interspersed are warm insertions for magnets and other devices. The SCL is then an alternating sequence of accelerating elements and drifts. No periodicity is present, and the longitudinal motion is not adiabatic. This has the consequence that the beam bunch ellipse will tumble, dilute and create a halo in the momentum plane because of inherent nonlinearities. When this is coupled to longitudinal space-charge forces, it may cause beam loss with latent activation of the accelerator components.
Date: June 19, 2003
Creator: RUGGIERO,A. G.
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

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

Nonlinear beam dynamics experimental program at SPEAR

Description: Since nonlinear effects can impose strict performance limitations on modern colliders and storage rings, future performance improvements depend on further understanding of nonlinear beam dynamics. Experimental studies of nonlinear beam motion in three-dimensional space have begun in SPEAR using turn-by-turn transverse and longitudinal phase-space monitors. This paper presents preliminary results from an on-going experiment in SPEAR.
Date: March 1, 1995
Creator: Tran, P.; Pellegrini, C.; Cornacchia, M.; Lee, M. & Corbett, W.
Partner: UNT Libraries Government Documents Department

Self-consistent beam halo studies & halo diagnostic development in a continuous linear focusing channel

Description: Beam halos are formed via self-consistent motion of the beam particles. Interactions of single particles with time-varying density distributions of other particles are a major source of halo. Aspects of these interactions are studied for an initially equilibrium distribution in a radial, linear, continuous focusing system. When there is a mismatch, it is shown that in the self-consistent system, there is a threshold in space-charge and mismatch, above which a halo is formed that extends to {approximately}1.5 times the initial maximum mismatch radius. Tools are sought for characterizing the halo dynamics. Testing the particles against the width of the mismatch driving resonance is useful for finding a conservative estimate of the threshold. The exit, entering and transition times, and the time evolution of the halo, are also explored using this technique. Extension to higher dimensions is briefly discussed.
Date: December 1, 1994
Creator: Jameson, R. A.
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

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

Final Report, IUT - B291527, January 1996 - March 1997

Description: The following note investigates scaling the 11.4-GHz TBNLC design of a relativistic klystron two-beam accelerator for a 30-GHz, 50-bunch accelerator design. We will refer to this point design as the RK-CLIC. We do not expect that the design will be optimal, but offer it as a starting point for discussions. In this memo, we begin with a general description of the RK-CLIC and drive beam dynamics, discuss required changes to major components, estimate the efficiency of wall plug to microwave power, and estimate costs. To be of interest the design must be such that it: (1) Can be installed at modest cost, (2) Operate with high wall plug to reconversion efficiency, and (3) Have acceptable drive beam dynamics.
Date: April 23, 1996
Creator: Henestroza, E.
Partner: UNT Libraries Government Documents Department

Normal mode tunes for linear coupled motion in six dimensional phase space. Informal report

Description: The motion of a particle in 6-dimensional phase space in the presence of linear coupling can be written as the sum of 3 normal mode. A cubic equation is found for the tune of the normal modes, which allows the normal mode tune to be computed from the 6 x 6 one turn transfer matrix. This result is similar to the quadratic equation found for the normal mode tune for the motion of a particle in 4-dimensional phase space. These results are useful in tracking programs where the one turn transfer matrix can be computed by multiplying the transfer matrices of each element of the lattice. The tune of the 3 normal modes for motion in 6-dimensional phase space can then be found by solving the cubic equation. Explicit solutions of the cubic equation for the tune are given in terms of the elements of the 6 x 6 one turn transfer matrix.
Date: January 1, 1995
Creator: Parzen, G.
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

Tevatron magnets and orbit vibrations

Description: We report results of recent measurements of vibrations of the Tevatron collider elements and orbit movements over large diapason of frequencies.
Date: October 25, 2002
Creator: Vladimir Shiltsev, Todd Johnson and Xiao-Long Zhang
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

Understanding the nonlinear beam dynamics of the Advanced Light Source

Description: Frequency map analysis is used to study the single particle transverse beam dynamics in ALS. The maps, which provide details about the diffusion of orbits and limits on long term stability, are generated by a postprocessor attached to a tracking code. This paper describes the method and shows how the map is changed when the 12- fold symmetry of the linear lattice is perturbed by including measured magnetic field imperfections. Also the long term stability of orbits that reside in regions of large diffusion is studied.
Date: September 18, 1996
Creator: Robin, D. & Laskar, J.
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