12 documents found, page 1 of 2
A new field solver for modeling of relativistic particle-laser interactions usi...
Li, F.; Miller, K. G.; Xu, X.; Tsung, F. S.; Decyk, V. K.; An, W.; Fonseca, R. A.; Mori, W. B.A customized finite-difference field solver for the particle-in-cell (PIC) algorithm that provides higher fidelity for wave-particle interactions in intense electromagnetic waves is presented. In many problems of interest, particles with relativistic energies interact with intense electromagnetic fields that have phase velocities near the speed of light. Numerical errors can arise due to (1) dispersion errors i...
Controlling the numerical Cerenkov instability in PIC simulations using a custo...
Li, F.; Yu, P. C.; Xu, X.; Fiuza, F.; Decyk, V. K.; Dalichaouch, T.; Davidson, A.; Tableman, A.; An, W.; Tsung, F. S.; Fonseca, R. A.; Lu, W.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 ...
Enabling Lorentz boosted frame particle-in-cell simulations of laser wakefield ...
Yu, P.; Xu, X.; Davidson, A.; Tableman, A.; Dalichaouch, T.; Li, F.; Meyers, M. D.; An, W.; Tsung, F. S.; Decyk, V. K.; Fiuza, F.; Vieira, J.When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at beta(b)c towards the laser, which can lead to a computational speedup of similar to gamma(2)(b)=(1-beta(2)(b))-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited n...
Mitigation of numerical Cerenkov radiation and instability using a hybrid finit...
Yu, P.; Xu, X.; Tableman, A.; Decyk, V. K.; Tsung, F. S.; Fiuza, F.; Vieira, J.; Davidson, A.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.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 ins...
Implementation of a hybrid particle code with a PIC description in r-z and a gr...
Davidson, A. W.; Tableman, A.; An, W.; Tsung, F. S.; Lu, W.; Vieira, J.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.For many plasma physics problems, three-dimensional and kinetic effects are very important. However, such simulations are very computationally intensive. Fortunately, there is a class of problems for which there is nearly azimuthal symmetry and the dominant three-dimensional physics is captured by the inclusion of only a few azimuthal harmonics. Recently, it was proposed [1] to model one such problem, laser wak...
Elimination of the numerical Cerenkov instability for spectral EM-PIC codes
Yu, P.; Xu, X.; Decyk, V. K.; Fiuza, F.; Vieira, J.; Tsung, F. S.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.When using an electromagnetic particle-in-cell (EM-PIC) code to simulate a relativistically drifting plasma, a violent numerical instability known as the numerical Cerenkov instability (NCI) occurs. The NCI is due to the unphysical coupling of electromagnetic waves on a grid to wave-particle resonances, including aliased resonances, i.e., omega + 2 pi mu/Delta t = (k(1) + 2 pi v(1)/Delta x(1))nu(0), where mu an...
Modeling of laser wakefield acceleration in Lorentz boosted frame using EM-PIC ...
Yu, P.; Xu, X.; Decyk, V. K.; An, W.; Vieira, J.; Tsung, F. S.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.Simulating laser wakefield acceleration (LWFA) in a Lorentz boosted frame in which the plasma drifts towards the laser with nu(b) can speed up the simulation by factors of gamma(2)(b) = (1 nu(2)(b)/c(2))(-1). In these simulations the relativistic drifting plasma inevitably induces a high frequency numerical instability that contaminates the interesting physics. Various approaches have been proposed to mitigate ...
Modeling of laser wakefield acceleration in Lorentz boosted frame using a Quasi...
Yu, P.; Davidson, A.; Xu, X.; Tableman, A.; Decyk, V. K.; Tsung, F. S.; Vieira, J.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.Recently it was proposed in [A. F. Lifschitz, et. al., J. Comp. Phys. 228, 1803 (2009)] that laser wakefield acceleration could be modeled efficiently using a particle-in-cell code in cylindrical coordinates if the fields and currents were expanded into Fourier modes in the azimuthal angle, ?. We have implemented this algorithm into OSIRIS, including a new rigorous charge conserving deposition routine applicabl...
Exploiting multi-scale parallelism for large scale numerical modelling of laser...
Fonseca, R. A.; Vieria, J.; Fiuza, F.; Davidson, A.; Tsung, F. S.; Mori, W. B.; Silva, L. O.A new generation of laser wakefield accelerators (LWFA), supported by the extreme accelerating fields generated in the interaction of PW-Class lasers and underdense targets, promises the production of high quality electron beams in short distances for multiple applications. Achieving this goal will rely heavily on numerical modelling to further understand the underlying physics and identify optimal regimes, but...
Numerical instability due to relativistic plasma drift in EM-PIC simulations
Xu, X.; Yu, P.; Martins, S. F.; Tsung, F. S.; Decyk, V. K.; Vieira, J.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.The numerical instability observed in electromagnetic particle-in-cell (EM-PIC) simulations with a plasma drifting with relativistic velocities is studied using both theory and computer simulations. We derive the numerical dispersion relation for a cold plasma drifting with a relativistic velocity, and find an instability attributed to the intersection between beam resonances and the electromagnetic modes in th...