A5044559226- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Particle Detector Development and Performance
- Distributed and Parallel Computing Systems
- Gyrotron and Vacuum Electronics Research
- Laser-Plasma Interactions and Diagnostics
- Scientific Computing and Data Management
- Quantum chaos and dynamical systems
- Advanced Data Storage Technologies
- Nonlinear Dynamics and Pattern Formation
- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Electromagnetic Simulation and Numerical Methods
- Chaos control and synchronization
- Parallel Computing and Optimization Techniques
- Radiative Heat Transfer Studies
- Laser-Matter Interactions and Applications
- Protein Structure and Dynamics
- Muon and positron interactions and applications
- solar cell performance optimization
- Advanced Thermodynamics and Statistical Mechanics
- Advanced Statistical Process Monitoring
Michigan State University
2023
Lawrence Berkeley National Laboratory
2012-2022
Los Alamos National Laboratory
1992-2013
Lawrence Livermore National Laboratory
2002
University of Maryland, College Park
1983-1999
Los Alamos National Security (United States)
1999
Indian Institute of Science Bangalore
1999
We develop a statistical approach for characterizing uncertainty in predictions that are made with the aid of computer simulation model. Typically, code models physical system and requires set inputs---some known specified, others unknown. A limited amount field data from true is available to inform us about unknown inputs also associated simulation-based prediction. The given here allows following:uncertainty regarding model (i.e., calibration); accounting due limitations on number...
Turning the current experimental plasma accelerator state-of-the-art from a promising technology into mainstream scientific tools depends critically on high-performance, high-fidelity modeling of complex processes that develop over wide range space and time scales. As part U.S. Department Energy's Exascale Computing Project, team Lawrence Berkeley National Laboratory, in collaboration with teams SLAC Accelerator Laboratory Livermore is developing new simulation tool will harness power future...
In this paper, we present a three-dimensional quasistatic model for high brightness beam dynamics simulation in rf/dc photoinjectors, rf linacs, and similar devices on parallel computers. model, electrostatic space-charge forces within charged particle are calculated self-consistently at each time step by solving the Poisson equation frame then transforming back to laboratory frame. When has large energy spread, it is divided into number of bins or slices so that from contribution bin summed...
The transverse motion of beam halo particles is described by a particle-core model which uses the space-charge field continuous cylindrical oscillating core in uniform linear focusing channel to provide force that drives large amplitudes. predicts maximum amplitude for resonantly-driven as function initial mismatch. We have calculated these limits and estimated growth times extended-halo formation both tune-depression ratio mismatch parameter. also present formulas scaling amplitudes...
We present a new method for the computation of Lyapunov exponents utilizing representations orthogonal matrices applied to decompositions $M$ or $M\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{M}$ where is tangent map. This uses minimal set variables, does not require renormalization reorthogonalization, can be used efficiently compute partial spectra, and break down when spectrum degenerate.
In this paper we report on large-scale high resolution simulations of beam dynamics in electron linacs for the next-generation x-ray free lasers (FELs). We describe key features a parallel macroparticle simulation code including three-dimensional (3D) space-charge effects, short-range structure wakefields, coherent synchrotron radiation (CSR) and treatment radio-frequency (rf) accelerating cavities using maps obtained from axial field profiles. present study microbunching instability causing...
A staged approach towards muon based facilities for Intensity and Energy Frontier science, building upon existing proposed at Fermilab, is presented. At each stage, a facility exploring new physics also provides an R&D platform to validate the technology needed subsequent stages. The envisioned program begins with nuSTORM, sensitive sterile neutrino search which precision cross-section measurements while developing of using cooling muons. Neutrino Factory Project X, sending beams Sanford...
The theory and simulation of coherent resonant coupling due to space charge in coasting or bunched anisotropic equilibrium beams is presented. Our work confirms that analytical results on oscillations instabilities KV (Kapchinskij-Vladimirskij) distributions are a valid tool interpret the findings from 2D 3D self-consistent particle-in-cell simulations for both waterbag distributions. With reference rings we discuss tune shifts up fourth order introduce coupled mode coefficient, which...
The Lyapunov exponents of a chaotic system quantify the exponential divergence initially nearby trajectories. For Hamiltonian systems are related to eigenvalues symplectic matrix. We make use this fact develop new method for calculation such systems. Our approach avoids renormalization and reorthogonalization usual techniques. It is also easily extendible damped apply our two examples physical interest: model that describes beam halo in charged particle beams driven van der Pol oscillator.
We have constructed, analytically and numerically, a class of self-consistent six-dimensional (6D) phase space stationary distributions. Stationary distributions allow us to study the halo development mechanism without it being obscured by beam redistribution its effect on formation. The is then mismatched longitudinally and/or transversely, we explore formation longitudinal transverse halos in 3D axisymmetric bunches. find that forms first for comparable mismatches because tune depression...
Viewed as approximations to quantum mechanics, classical evolutions can violate the positive semidefiniteness of density matrix. The nature violation suggests a classification dynamical systems based on classical-quantum correspondence; we show that this be used identify when environmental interaction (decoherence) will unsuccessful in inducing quantum-classical transition. In particular, late-time Wigner function become without any corresponding approach dynamics. light these results,...
MARYLIE 3.0 is a Fortran-language beam transport and tracking code developed at the University of Maryland. It employs algorithms based on Lie algebraic formalism for charged particle trajectory calculations/sup 1/, designed to compute transfer maps trace rays through single or multiple beam-line elements. This done without use numerical integration traditional matrix methods; all nonlinearities (including chromatic effects) third (octupole) order are included. Thus includes effects one...
In this paper we present a new approach, based on shifted Green function, to evaluate the electromagnetic field in simulation of colliding beams. Unlike conventional particle-mesh code, use method which computational mesh covers only largest two This allows us study long-range parasitic collisions accurately and efficiently. We have implemented algorithm parallel strong-strong beam-beam code. As an application, beam sweeping scheme for LBNL luminosity monitor Large Hadron Collider.
This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling next-generation accelerator designs. The first technique, based on a hybrid approach, makes possible exploration large-scale particle beam dynamics modeling. second compact texture-enhanced representation, exploits advanced features commodity graphics cards to achieve perceptually effective very dense and complex electromagnetic...
In this paper, we describe in detail a method of computing Lyapunov exponents for continuous-time dynamical system and extend the to discrete maps. Using method, partial spectrum can be computed using fewer equations as compared computation full spectrum, there is no difficulty evaluating degenerate spectra, are straightforward generalize higher dimensions, minimal set variables used. Explicit proofs other details not given previous work included here.
Energy exchange between the longitudinal and transverse degrees of freedom nonequipartitioned bunched beams (non-neutral plasmas) is investigated by means 3D simulation. It found that collective instability may lead to energy transfer in direction equipartition, without full progression it, certain bounded regions parameter space where internal resonance conditions are satisfied, good agreement with stability charts from an earlier derived 2D Vlasov analysis. Nonequipartitioned stable...
A realistic treatment of halo formation must take into account 3D beam bunches and 6D phase space distributions. We recently constructed, analytically numerically, a new class self-consistent stationary distributions, which allowed us to study the development mechanism without being obscured by effect redistribution. In this paper we consider nonstationary distributions how characteristics compare with those obtained using distribution. then discuss redistribution on mechanism. contrast...
A new method is presented for solving Poisson's equation inside an open-ended rectangular pipe. The uses Fast Fourier Transforms (FFTs) to perform mixed convolutions and correlations of the charge density with Green function. Descriptions are provided algorithms based on ordinary function integrated (IGF). Due its similarity widely used Hockney algorithm in free space, this capability can be easily implemented many existing particle-in-cell beam dynamics codes.