COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Beam Dynamics Overview Robert D. Ryne COMPASS all-hands meeting Sept 17-18, 2007 Fermilab

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Overall Goals Develop advanced beam dynamics capability to meet the mission needs of DOE/SC HEP, NP, and BES accelerator projects Develop reusable software components to produce a comprehensive, scalable (to petascale), lasting accelerator modeling capability for present and future accelerator projects

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne COMPASS Beam Dynamics physics areas fall mainly in 7 categories 1.Space-charge 2.Beam-beam 3.Multi-species 4.Beam-environment 5.Optics, errors, feedback 6.High brightness e-beams, radiation 7.IBS

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Space Charge Maintain SciDAC1 solvers, port/optimize for SciDAC2 platforms Develop/incorporate new solvers, working math math/cs partners, to meet new requirements (boundary conditions, etc) —See math/cs talks Tuesday

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Beam-beam effects Codes used —BeamBeam3D —Lifetime,Nimzovitch

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne BeamBeam3D Developed by Ji Qiang Multiple models (strong-strong, weak-strong) Multi-slice (finite bunch length effects) New algorithm -- Shifted Green function -- efficiently treats long-range parasitic collisions Particle-based decomp (perfect load balance) Lorentz boost handles crossing angle collisions Multi-IP collisions, varying phase advance,… Arbitrary closed orbit sep (static or time-dep) Applied to Tevatron, LHC, PEP-II, KEK-B, RHIC, RHIC/LARP RHIC B-B  -growth vs x, y Strong collaboration, code development by Stern et al at FNAL —Fourier 3D solver validated with observed synchro-betatron modes —Resistive-wall impedance model growth rate matches predictions —Chromaticity with coupled-motion maps and impedance matches predictions —Arbitrary bunch collision patterns w/ measured Tevatron optics & helix incorporated

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne BeamBeam3D code validation comparing with VEPP-II data (E. Stern, A. Valisev, FNAL; J. Qiang, LBNL) Beam-beam code validation comparing with VEPP-II data

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Sequence of frames from a BeamBeam3D simulation of a collision at the 200x nominal intensity (E. Stern, FNAL)

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Lifetime, Nimzovitch Developed by Andreas Kabel LIFETIME application —Uses PLIBB to calculate lifetimes in storage rings; applied to Tevatron, RHIC current wire experiment, LHC NIMZOVITCH —Strong-strong beam-beam code optimized for large number of bunches/IP’s/parasitic crossings

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Beam-beam plans BeamBeam3D: —Implement wire compensation model —Implement rotating beam colliding w/crossing angle, test on LHC luminosity monitor —Implement full nonlinear symplectic tracking —Implement quantum effects, test and perform high- resolution simulation of ILC beam-beam interactions —Incorporate solver into multi-physics framework —Use to investigate antiproton intensity limits in the Tevatron and the growth of multi-bunch modes and electron cooling beam-beam compensation operation

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Beam-beam plans, cont. Nimzovitch: —Make Nimzovitch go away by reformulating under enhanced PLIBB: more physics (IBS, noise, imperfections) low noise PIC enforce symplectic correctness in 3D beamline parallelization for multi-bunch calculations Lifetime: —Apply PLIBB w/ IBS module to RHIC, experimental validation —Strong-strong module: apply to LHC multi-bunch effects

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Multi-species effects Main emphasis on electron-cloud 2 approaches: —Full 3D using WARP/POSINST (A. Friedman, D. Grote, J.L.-Vay, M. Furman, et al) —Quasi-static using QuickPIC (W. Mori, V. Decyk, T. Katsouleas et al) e-e- i+i+ halo e-e- i + = ion e - = electron g = gas  = photon = instability Positive Ion Beam Pipe e-e- i+i+ g g e-e- e-e- e-e- e-e- e-e-  Ionization of - background gas - desorbed gas ion induced emission from - expelled ions hitting vacuum wall - beam halo scraping photo-emission from synchrotron radiation (HEP) secondary emission from electron-wall collisions

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Calculating the e-cloud effects in the ILC DR wiggler is an immense numerical challenge 3D - fields and dynamics Self-consistent (beam  electrons) Large range of spatial scales (sets resolution,  memory req’t) transverse: longitudinal: Must resolve beam, but 3000 x 3000 x 6000 ~ cell mesh! Huge number of timesteps required  t = (e - traverse <1 cell in 1 timestep)

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne E-cloud modeling using WARP-POSINST 3D field dynamics and dynamics Fully self-consistent Realistic boundary conditions Detailed electron generation models (POSINST, including energy spectrum) Drift Lorentz electron “mover” (correct space charge w/out resolving cyclic orbit) Mesh refinement (spatial resolution only where needed -- essential!) Velocity sub-cycling (small  t only for particles that need it) Parallelized

QuickPIC uses a quasi-static model; under certain circumstances, agrees well with self-consistent but is orders of magnitude faster A 2-D slab of electrons (macroparticles) is stepped backward (with small time steps) through the beam field and 2-D electron fields are stacked in a 3-D array, that is used to push the 3-D beam ions (with large time steps) using maps (as in HEADTAIL-CERN) or Leap-Frog (as in QUICKPIC-UCLA/USC). 2-D slab of electrons 3-D beam benddrift quad s s0s0 lattice 100x improvement with “no” loss in accuracy

QuickPIC: Pipelining

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Calculation in boosted frame provides x10 n speedup* - proton bunch through a given e – cloud- hose instability of a proton bunch Proton energy:  = 500 in Lab L= 5 km, continuous focusing Code: WARP (Particle-In-Cell) electron streamlines beam proton bunch radius vs. z CPU time: lab frame: >2 weeks frame with  2 =512: <30 min CPU time: lab frame: >2 weeks frame with  2 =512: <30 min Speedup x1000 *J.-L. Vay, PRL 98, (2007)

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne WARP-POSINST plans Code needs development to perform run in boosted frame and complete set of e-cloud related physics —Implementation of magnetoinductive (“Darwin”) model, or reduce version of it if sufficient, —implement an interface linking zones of 3-D PIC simulations to zones of MAPS transport in beween, —upgrade diagnostics to allow for results given in frame different from the one of calculation, —implement self-consistent generation and tracking of photo-electrons, based on Monte-Carlo methods, —implement adaptive macro-particle management (reduction/coalescence), —upgrade parallel decomposition from 1-D to 2-D/3-D.

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Beam-environment interactions Maintain SciDAC1 wakefield modules, port/optimize for SciDAC2 platforms Implement circuit model for time-dep beam loading effects Fully self-consistent calculation using VORPAL

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Optics, errors, feedback Maintain existing optics libraries that are used in the BD framework, port/optimize for SciDAC2 platforms Extend multi-bunch capabilities Implement models for dynamically changing quantities (e.g. jitter), machine errors, and feedback systems

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne High brightness electron beam dynamics Codes used: —Elegant —IMPACT (collaboration with synergistic high brightness e-beam activities at LBNL funded by other sources) Essential goal of this work is to support LCLS commissioning, operation, and optimization with fast, high-fidelity modeling tools Large scale computing essential for detailed study of the microbunching instability

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Elegant: status and limitations CSR and longitudinal space charge parallelized in elegant Limited to ~60 million particles presently With ~1.5 billion particles we could look at modulations on the 1 mm level relevant to proposed laser/undulator beam heaters Addressing I/O and memory management issues related to this Present fast CSR algorithms are 1-d simplifications Existing 3-d algorithms are coarse-grained, time-consuming No standardized, accepted tools exist for transferring information between various accelerator codes (elegant, IMPACT) and radiation modeling codes (GINGER, GENESIS, SPUR) No way to take a snapshot of an existing FEL, simulate it, then compare simulated and real diagnostics LCLS is already reporting [Frisch, PAC07] unexplained effects with very short bunches in the first compressor Must be able to optimize to match a selection of diagnostics, then extrapolate to other diagnostics

FERMI FEL Microbunching Instability Simulated with elegant BLSBC1BC2 Tiny initial density modulations build up in bunch compression systems due to CSR and space charge. Gain increases to ~2000-fold down to 25  m modulation. Can't presently go shorter than this! Tiny initial density modulations build up in bunch compression systems due to CSR and space charge. Gain increases to ~2000-fold down to 25  m modulation. Can't presently go shorter than this!

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne IMPACT: status and limitations Successfully used to perform 1B macroparticle simulations of Fermi FEL linac Limitations: 1D CSR model, difficult to use for design optimization, simple matrix description of RF elements, not fully integrated with FEL codes

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne 1B particle simulation of microbunching in FERMI FEL linac using IMPACT Final Longitudinal Phase Space Distribution Using 10M and 1B particles (init. 15 keV energy spread, 2BCs)

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Summary of ANL’s tasks/plans Finish parallelization of elegant Develop accepted, robust interfaces among suite of codes involved in FEL modeling —IMPACT (gun and linac modeling) —elegant (accelerator modeling and optimization) —GENESIS and GINGER (FEL modeling) Develop integrated graphical user interface to provide on-demand, high-fidelity modeling of data and experients —Selection of codes, algorithms, detail level —Utilizes data drawn from the control system —Utilizes high-performance computing resources Develop optimizer based on genetic algorithm to provide guidance on FEL performance improvement.

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne IMPACT development plans for high brightness e-beam (funded by LDRD and other non-SciDAC projects) Develop and implement interfaces for start- to-undulator parallel simulation Fully self-consistent CSR (difficult!) Automatic beam steering Integration with optimization tool Incorporate nonlinear model of RF beamline elements

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Frameworks Synergia/SciDAC1 IMPACT suite MaryLie/IMPACT UPIC PLIBB

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Synergia/SciDAC1 See next talk

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne IMPACT A code suite (linac design, 3D rms code, 2 parallel PIC tracking codes) developed under SciDAC1 Includes IMPACT-Z and IMPACT-T 3D parallel PIC codes Applicable to electron and ion accelerators Recent enhancements —Cathode emission model; cathode image effects —Energy binning for large  E —Multi-charge state capability (RIA) —SW and TW structures —wakefields —1D CSR IMPACT-T now widely used for photoinjector modeling —BNL e-cooling project, Cornell ERL, FNAL/A0, LBNL/APEX, ANL, JLAB, SLAC/LCLS, Emission from nano-needle tip

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne MaryLie/IMPACT (ML/I) Hybrid code combining MaryLie beam optics with IMPACT parallel PIC + new capabilities —Embeds operator splitting for all thick elements —Allows mixed MaryLie and MAD input —New software modules (wakefields, soft- edge magnet models, …) add functionality —Performance optimization (R. Gerber, NERSC staff) Multiple uses all within in the same code —Particle tracking, envelope tracking, map production, map analysis, lattice functions, fitting. User manual and example suite Contributions from many people from many disciplines (follows the SciDAC model) damping ring simulation with MLI

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne PLIBB particle dynamics framework Developed at SLAC (A. Kabel) a general-purpose C++ framework for high-speed, parallel tracking studies fast and easily extensible through compile-time polymorphism easily applied: MAD{X,8} beamline parsers & manipulators physics: magnetic elements, cavities, wakefields, beam-beam analysis: statistics, differential algebra, collective quantities

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne UPIC Framework for Parallel PIC Developed by V. Decyk Layered, Fortran based, but could be called from C/C++ Goals: —Rapid construction of new parallel PIC codes from trused components —High accuracy testbed for evaluating and verifying PIC algorithms Supports —Multiple plasma models: electrostatic, Darwin, electromagnetic —Multiple boundary conditions: periodic, dirichlet, neumann, open3. Multiple levels of accuracy: linear, quadratic, gridless4. Multiple programming paradigms: procedural, object-oriented5. Multiple parallel models: threads, message-passing. Used in QuickPIC and other applications

COMPASS all-hands meeting 9/17-18/2007 Robert Ryne Frameworks: Plans See next talk