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Dynamic load balancing with enhanced shared-memory parallelism for particle-in-cell codes [article]

Kyle G. Miller, Roman P. Lee, Adam Tableman, Anton Helm, Ricardo A. Fonseca, Viktor K. Decyk, Warren B. Mori
2020 arXiv   pre-print
Furthering our understanding of many of today's interesting problems in plasma physics---including plasma based acceleration and magnetic reconnection with pair production due to quantum electrodynamic effects---requires large-scale kinetic simulations using particle-in-cell (PIC) codes. However, these simulations are extremely demanding, requiring that contemporary PIC codes be designed to efficiently use a new fleet of exascale computing architectures. To this end, the key issue of parallel
more » ... ad balance across computational nodes must be addressed. We discuss the implementation of dynamic load balancing by dividing the simulation space into many small, self-contained regions or "tiles," along with shared-memory (e.g., OpenMP) parallelism both over many tiles and within single tiles. The load balancing algorithm can be used with three different topologies, including two space-filling curves. We tested this implementation in the code OSIRIS and show low overhead and improved scalability with OpenMP thread number on simulations with both uniform load and severe load imbalance. Compared to other load-balancing techniques, our algorithm gives order-of-magnitude improvement in parallel scalability for simulations with severe load imbalance issues.
arXiv:2003.10406v1 fatcat:scowk2buxbh67b7onofiqrxabq

Generating high quality ultra-relativistic electron beams using an evolving electron beam driver [article]

Thamine Dalichaouch, Xinlu Xu, Fei Li, Adam Tableman, Frank Tsung, Weiming An, Warren Mori
2019 arXiv   pre-print
A new method of controllable injection to generate high quality electron bunches in the nonlinear blowout regime driven by electron beams is proposed and demonstrated using particle-in-cell simulations. Injection is facilitated by decreasing the wake phase velocity through varying the spot size of the drive beam and can be tuned through the Courant-Snyder (CS) parameters. Two regimes are examined. In the first, the spot size is focused according to the vacuum CS beta function, while in the
more » ... d, it is focused by the plasma ion column. The effects of the driver intensity and vacuum CS parameters on the wake velocity and injected beam parameters are examined via theory and simulations. For plasma densities of ∼ 10^19 cm^-3, particle-in-cell (PIC) simulations demonstrate that peak normalized brightnesses ≳ 10^20 A/m^2/rad^2 can be obtained with projected energy spreads of ≲ 1% within the middle section of the injected beam, and with normalized slice emittances as low as ∼ 10 nm.
arXiv:1909.02689v2 fatcat:5toznmpwsrcu3k4tmdcy5ppb6a

Accurately simulating nine-dimensional phase space of relativistic particles in strong fields [article]

Fei Li, Viktor K. Decyk, Kyle G. Miller, Adam Tableman, Frank S. Tsung, Marija Vranic, Ricardo A. Fonseca, Warren B. Mori
2021 arXiv   pre-print
Next-generation high-power lasers that can be focused to intensities exceeding 10^23 W/cm^2 are enabling new physics and applications. The physics of how these lasers interact with matter is highly nonlinear, relativistic, and can involve lowest-order quantum effects. The current tool of choice for modeling these interactions is the particle-in-cell (PIC) method. In strong fields, the motion of charged particles and their spin is affected by radiation reaction. Standard PIC codes usually use
more » ... is or its variants to advance the particles, which requires very small time steps in the strong-field regime to obtain accurate results. In addition, some problems require tracking the spin of particles, which creates a 9D particle phase space (x, u, s). Therefore, numerical algorithms that enable high-fidelity modeling of the 9D phase space in the strong-field regime are desired. We present a new 9D phase space particle pusher based on analytical solutions to the position, momentum and spin advance from the Lorentz force, together with the semi-classical form of RR in the Landau-Lifshitz equation and spin evolution given by the Bargmann-Michel-Telegdi equation. These analytical solutions are obtained by assuming a locally uniform and constant electromagnetic field during a time step. The solutions provide the 9D phase space advance in terms of a particle's proper time, and a mapping is used to determine the proper time step for each particle from the simulation time step. Due to the analytical integration, the constraint on the time step needed to resolve trajectories in ultra-high fields can be greatly reduced. We present single-particle simulations and full PIC simulations to show that the proposed particle pusher can greatly improve the accuracy of particle trajectories in 9D phase space for given laser fields. A discussion on the numerical efficiency of the proposed pusher is also provided.
arXiv:2007.07556v3 fatcat:j4gonhv2a5h75k56quxc3ahusq

Relativistically induced transparency acceleration of light ions by an ultrashort laser pulse interacting with a heavy-ion-plasma density gradient

Aakash A. Sahai, Frank S. Tsung, Adam R. Tableman, Warren B. Mori, Thomas C. Katsouleas
2013 Physical Review E  
The relativistically induced transparency acceleration (RITA) scheme of proton and ion acceleration using laser-plasma interactions is introduced, modeled, and compared to the existing schemes. Protons are accelerated with femtosecond relativistic pulses to produce quasimonoenergetic bunches with controllable peak energy. The RITA scheme works by a relativistic laser inducing transparency to densities higher than the cold-electron critical density, while the background heavy ions are
more » ... The rising laser pulse creates a traveling acceleration structure at the relativistic critical density by ponderomotively driving a local electron density inflation, creating an electron snowplow and a co-propagating electrostatic potential. The snowplow advances with a velocity determined by the rate of the rise of the laser's intensity envelope and the heavy-ion-plasma density gradient scale length. The rising laser is incrementally rendered transparent to higher densities such that the relativistic-electron plasma frequency is resonant with the laser frequency. In the snowplow frame, trace density protons reflect off the electrostatic potential and get snowplowed, while the heavier background ions are relatively unperturbed. Quasimonoenergetic bunches of velocity equal to twice the snowplow velocity can be obtained and tuned by controlling the snowplow velocity using laser-plasma parameters. An analytical model for the proton energy as a function of laser intensity, rise time, and plasma density gradient is developed and compared to 1D and 2D PIC OSIRIS simulations. We model the acceleration of protons to GeV energies with tens-of-femtoseconds laser pulses of a few petawatts. The scaling of proton energy with laser power compares favorably to other mechanisms for ultrashort pulses.
doi:10.1103/physreve.88.043105 pmid:24229291 fatcat:ybiwgqodjjbv3dmk2hz5vwpblq

Enabling Lorentz boosted frame particle-in-cell simulations of laser wakefield acceleration in quasi-3D geometry

Peicheng Yu, Xinlu Xu, Asher Davidson, Adam Tableman, Thamine Dalichaouch, Fei Li, Michael D. Meyers, Weiming An, Frank S. Tsung, Viktor K. Decyk, Frederico Fiuza, Jorge Vieira (+4 others)
2016 Journal of Computational Physics  
When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at β_b c towards the laser, which can lead to a computational speedup of ∼γ_b^2=(1-β_b^2)^-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional problems with the
more » ... on load on the order of two dimensional r-z simulations. Here, we describe how to combine the speed ups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that can be used to effectively eliminate the Numerical Cerenkov Instability (NCI) that inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simulations. In addition, based on the space-time distribution of the LWFA data in the lab and boosted frame, we propose to use a moving window to follow the drifting plasma to further reduce the computational load. We describe the details of how the NCI is eliminated for the quasi-3D geometry, the setups for simulations which combine the Lorentz boosted frame and quasi-3D geometry, the use of a moving window, and compare the results from these simulations against their corresponding lab frame cases. Good agreement is obtained, particularly when there is no self-trapping, which demonstrates it is possible to combine the Lorentz boosted frame and the quasi-3D algorithms when modeling LWFA to achieve unprecedented speedups.
doi:10.1016/ fatcat:bgxpcev565gurgiclpfv6mn2de

Controlling the numerical Cerenkov instability in PIC simulations using a customized finite difference Maxwell solver and a local FFT based current correction

Fei Li, Peicheng Yu, Xinlu Xu, Frederico Fiuza, Viktor K. Decyk, Thamine Dalichaouch, Asher Davidson, Adam Tableman, Weiming An, Frank S. Tsung, Ricardo A. Fonseca, Wei Lu (+1 others)
2017 Computer Physics Communications  
In this paper we present a customized finite-difference-time-domain (FDTD) Maxwell solver for the particle-in-cell (PIC) algorithm. The solver is customized to effectively eliminate the numerical Cerenkov instability (NCI) which arises when a plasma (neutral or non-neutral) relativistically drifts on a grid when using the PIC algorithm. We control the EM dispersion curve in the direction of the plasma drift of a FDTD Maxwell solver by using a customized higher order finite difference operator
more » ... r the spatial derivative along the direction of the drift (1̂ direction). We show that this eliminates the main NCI modes with moderate k_1 , while keeps additional main NCI modes well outside the range of physical interest with higher k_1 . These main NCI modes can be easily filtered out along with first spatial aliasing NCI modes which are also at the edge of the fundamental Brillouin zone. The customized solver has the possible advantage of improved parallel scalability because it can be easily partitioned along 1̂ which typically has many more cells than other directions for the problems of interest. We show that FFTs can be performed locally to current on each partition to filter out the main and first spatial aliasing NCI modes, and to correct the current so that it satisfies the continuity equation for the customized spatial derivative. This ensures that Gauss' Law is satisfied. We present simulation examples of one relativistically drifting plasmas, of two colliding relativistically drifting plasmas, and of nonlinear laser wakefield acceleration (LWFA) in a Lorentz boosted frame that show no evidence of the NCI can be observed when using this customized Maxwell solver together with its NCI elimination scheme.
doi:10.1016/j.cpc.2017.01.001 fatcat:avdpe3gb7nbanmr56sizvosmeq

Mitigation of numerical Cerenkov radiation and instability using a hybrid finite difference-FFT Maxwell solver and a local charge conserving current deposit

Peicheng Yu, Xinlu Xu, Adam Tableman, Viktor K. Decyk, Frank S. Tsung, Frederico Fiuza, Asher Davidson, Jorge Vieira, Ricardo A. Fonseca, Wei Lu, Luis O. Silva, Warren B. Mori
2015 Computer Physics Communications  
A hybrid Maxwell solver for fully relativistic and electromagnetic (EM) particle-in-cell (PIC) codes is described. In this solver, the EM fields are solved in k space by performing an FFT in one direction, while using finite difference operators in the other direction(s). This solver eliminates the numerical Cerenkov radiation for particles moving in the preferred direction. Moreover, the numerical Cerenkov instability (NCI) induced by the relativistically drifting plasma and beam can be
more » ... ted using this hybrid solver by applying strategies that are similar to those recently developed for pure FFT solvers. A current correction is applied for the charge conserving current deposit to correctly account for the EM calculation in hybrid Yee-FFT solver. A theoretical analysis of the dispersion properties in vacuum and in a drifting plasma for the hybrid solver is presented, and compared with PIC simulations with good agreement obtained. This hybrid solver is applied to both 2D and 3D Cartesian and quasi-3D (in which the fields and current are decomposed into azimuthal harmonics) geometries. Illustrative results for laser wakefield accelerator simulation in a Lorentz boosted frame using the hybrid solver in the 2D Cartesian geometry are presented, and compared against results from 2D UPIC-EMMA simulation which uses a pure spectral Maxwell solver, and from OSIRIS 2D lab frame simulation using the standard Yee solver. Very good agreement is obtained which demonstrates the feasibility of using the hybrid solver for high fidelity simulation of relativistically drifting plasma with no evidence of the numerical Cerenkov instability.
doi:10.1016/j.cpc.2015.08.026 fatcat:ubenep4j2veqhj7ojnjdyfyfky

Lorentz boosted frame simulation of Laser wakefield acceleration using hybrid Yee-fft solver in quasi-3d geometry

Peicheng Yu, Asher Davidson, Viktor Decyk, Frederico Fiuza, Ricardo Fonseca, Wei Lu, Warren Mori, Luis Silva, Adam Tableman, Frank Tsung, Jorge Vieira, Xinlu Xu (+4 others)
We present results from a preliminary study on modeling Laser wakefield acceleration (LWFA) with OSIRIS in a Lorentz boosted frame using a quasi-3D algorithm. In the quasi-3D algorithm, the fields and currents are expanded into azimuthal harmonics and only a limited number of harmonics are kept. Field equations in (r,z) space are solved for a desired number of harmonics in φ. To suppress the numerical Cerenkov instability (NCI) that inevitably arises due to the relativistic plasma drift in the
more » ... imulation, we use a hybrid Yee-FFT solver in which the field equations are solved in (k_{z}, r) space, where \hat{z} is the drifting direction. Preliminary results show that high fidelity LWFA boosted frame simulations can be carried out with no evidence of the NCI. Good agreement is found when comparing LWFA boosted frame simulations in the full 3D geometry against those in the quasi-3D geometry. In addition, we discuss how the moving window can be combined with the hybrid Yee-FFT solver to further speed up the simulation. The results indicate that unprecedented speed ups for LWFA simulations can be achieved when combining the Lorentz boosted frame technique, the quasi-3D algorithm, and a moving window.
doi:10.18429/jacow-ipac2015-mopma059 fatcat:xgedidbhrjcshfn2z4z57xuaja

Page 403 of American Society of Civil Engineers. Proceedings of the American Society of Civil Engineers Vol. 65, Issue 4 [page]

1939 American Society of Civil Engineers. Proceedings of the American Society of Civil Engineers  
., 225 North Adams = Green Bay, Wis.  ...  ROOSA, PAUL ROBERT (Jun. °38), Plane Tableman, Bureau of Reclamation, Phoenix, an. (Res., 2010 South Broadway, Boulder, olo.).  ... 

Page 83 of Chemical Engineering Progress Vol. 57, Issue 11 [page]

1961 Chemical Engineering Progress  
Tableman, sis. mgr.; W. L. Hamill, sis. rep. Adams, R. P., Co., Inc. Buffalo, N. Y. Aero Flow Dynamics, Inc. Linden, N. J. L. J. Wing Mfg. Co A.1.Ch.E.  ... 

Maternal History of Adverse Experiences and Posttraumatic Stress Disorder Symptoms Impact Toddlers' Early Socioemotional Wellbeing: The Benefits of Infant Mental Health-Home Visiting

Julie Ribaudo, Jamie M. Lawler, Jennifer M. Jester, Jessica Riggs, Nora L. Erickson, Ann M. Stacks, Holly Brophy-Herb, Maria Muzik, Katherine L. Rosenblum
2022 Frontiers in Psychology  
Acknowledgments The authors would like to thank Lillian Adam for her assistance in writing the manuscript.  ...  J., and Tableman, B. (2017). A collaborative process for evaluating infant mental health home visiting in Michigan.  ... 
doi:10.3389/fpsyg.2021.792989 pmid:35111107 pmcid:PMC8802330 fatcat:z2tmars3nfac5ehmrs2rahqmtq

Page 939 of Psychological Abstracts Vol. 77, Issue Author Index 1-2 [page]

Psychological Abstracts  
Behavioral Neuro- science, 1990(Feb), Vol 104(1), 217-225. 19340 Szymusik, Adam; Orwid, Maria & Piotrowski, Andrzej.  ...  Psychotherapy Patient, 1989, Vol 5(3-4), oe. . 1 Tableman, Betty. Installing prevention programming in the public mental health system.  ... 

Behavioural Development Of Early Adolescents By Dint Of Positive School Climate

Jayalekshmi N.B, B. William Dharma Raja
2011 i-manager's Journal on Educational Psychology  
Research suggests that positive school climate is associated with reduced aggression and violence (Meyer-Adams & Conner, 2008).  ...  It reflects the physical and psychological aspects of the school that are mere susceptible to change and that provide the preconditions necessary for teaching and learning to take place (Tableman, 2004  ... 
doi:10.26634/jpsy.5.2.1608 fatcat:xakvvrhfhzestkosrfitlulmyq

Turning around at-risk schools: what effective principals do

Sharifah Md Nor, Samsilah Roslan
2008 International Journal on School Disaffection  
Instead of being a dumping ground for students who could not get into other schools, he was adamant about making the school the pride of the community.  ...  School climate can be discerned based on four aspects of school environment Tableman, (2004) , namely the physical environment, the social environment, the affective environment and the academic environment  ... 
doi:10.18546/ijsd.06.2.04 fatcat:kume4jmutrccncad5djogaokcq

Personal and Miscellaneous

Frederic A. Ogg
1949 American Political Science Review  
Marvin Tableman, of the University of Michigan, and Walter 0.  ...  Adams has returned to his former post at the University of Buffalo. Professor David B. Truman, of Williams College, will teach at that institution during the coming summer. Dr. Alonzo L.  ... 
doi:10.1017/s0003055400063541 fatcat:xv5ytr3kjnetbjews6pxjp2zga
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