No abstract

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 a wide range of space and time scales. As part of the U.S. Department of Energy's Exascale Computing Project, a team from Lawrence Berkeley National Laboratory, in collaboration with teams from SLAC National Accelerator Laboratory and Lawrence Livermore National Laboratory, is developing a new plasma accelerator simulation tool that will harness the power of future exascale supercomputers for high-performance modeling of plasma accelerators. We present the various components of the codes such as the new Particle-In-Cell Scalable Application Resource (PICSAR) and the redesigned adaptive mesh refinement library AMReX, which are combined with redesigned elements of the Warp code, in the new WarpX software. The code structure, status, early examples of applications and plans are discussed.

The scattering of the H-and E-polarized plane waves by a thin flat homogeneous magneto-dielectric strip is considered. Assuming the strip to be thinner than the wavelength, we shrink its cross-section to the median line where the generalized boundary conditions are imposed. The numerical solution is built on two singular integral equations discretized using Nystrom-type numerical algorithm. The obtained results demonstrate fast convergence and good agreement with data known for the limiting values of the strip parameters. This opens a way to the accurate numerical analysis of various striplike configurations simulating natural objects and electromagnetic circuit components, both in traditional microwave applications and nanophotonics.Index Terms-Discrete mathematical model, generalized two-side boundary conditions, scattering cross-sections, singular and hyper-singular integral equations, strip scatterer.

The excitation of the surface plasmon resonances on a graphene strip and a disk in free space is studied numerically as a 2D and 3D electromagnetic wave-scattering problem, respectively. The associated mathematical model is based on the Maxwell equations with resistive boundary conditions on the surface of a zero-thickness strip or disk, where the graphene electron conductivity is included as a parameter and determined from the Kubo formalism. It is shown that plasmon resonance frequencies in the terahertz range shift with variation of the chemical potential of the graphene. Far-field and near-field patterns are plotted at several resonance frequencies.

Considered are the problems of electromagnetic wave scattering, absorption and emission by several types of twodimensional and three-dimensional dielectric and metallic objects: arbitrary dielectric cylinder, thin material strip and disk, and arbitrary perfectly electrically conducting surface of rotation. In each case, the problem is rigorously formulated and reduced to a set of boundary integral equations with smooth, singular and hyper-singular kernel functions. These equations are further discretized using Nystrom-type quadrature formulas adapted to the type of kernel singularity and the edge behavior of unknown function. Convergence of discrete models to exact solutions is guaranteed by general theorems. Practical accuracy is achieved by inverting the matrices of the size that is only slightly greater than the maximum electrical dimension of corresponding scatterer. Sample numerical results are presented.