Higher-order particle representation for particle-in-cell simulations

In this paper we present an alternative approach to the representation of simulation particles for unstructured electrostatic and electromagnetic PIC simulations. In our modified PIC algorithm we represent particles as having a smooth shape function limited by some specified finite radius, . A unique feature of our approach is the representation of this shape by surrounding simulation particles with a set of virtual particles with delta shape, with fixed offsets and weights derived from Gaussian quadrature rules and the value of . As the virtual particles are purely computational, they provide the additional benefit of increasing the arithmetic intensity of traditionally memory bound particle kernels. The modified algorithm is implemented within Sandia National Laboratories' unstructured EMPIRE-PIC code, for electrostatic and electromagnetic simulations, using periodic boundary conditions. We show results for a representative set of benchmark problems, including electron orbit, a transverse electromagnetic wave propagating through a plasma, numerical heating, and a plasma slab expansion. Good error reduction across all of the chosen problems is achieved as the particles are made progressively smoother, with the optimal particle radius appearing to be problem-dependent

Extreme Scale Plasma Turbulence Simulations on Top Supercomputers Worldwide

The goal of the extreme scale plasma turbulence studies described in this paper is to expedite the delivery of reliable predictions on confinement physics in large magnetic fusion systems by using world-class supercomputers to carry out simulations with unprecedented resolution and temporal duration. This has involved architecture-dependent optimizations of performance scaling and addressing code portability and energy issues, with the metrics for multi-platform comparisons being 'time-to-solution' and 'energy-to-solution'. Realistic results addressing how confinement losses caused by plasma turbulence scale from present-day devices to the much larger $25 billion international ITER fusion facility have been enabled by innovative advances in the GTC-P code including (i) implementation of one-sided communication from MPI 3.0 standard; (ii) creative optimization techniques on Xeon Phi processors; and (iii) development of a novel performance model for the key kernels of the PIC code. Results show that modeling data movement is sufficient to predict performance on modern supercomputer platforms

Paralelizacion del modelo PCell para la simulacion de celdas de plasma convectivo

Las simulaciones de plasma son inherentemente complejas debido a la cantidad de procesos que ocurren naturalmente a la materia en este estado. Las simulaciones computacionales y las visualizaciones de plasma ayudan a investigadores y científicos a entender y estudiar sus propiedades y comportamiento. En esta investigación se desarrolló una implementación paralela de una aplicación utilizada para simular y visualizar el proceso de convección en celdas de plasma. Esta aplicación implementa un enfoque de magnetohidrodinámica (MHD) a la hora de simular los procesos del plasma. Los resultados de las evaluaciones experimentales con la aplicación paralelizada se presentan y analizan. Se alcanzó una aceleración del programa secuencial por un factor de alrededor de 42× después de optimizar algunas funciones y paralelizarlas con OpenMP utilizando 128 núcleos de un servidor Intel Xeon Phi KNL. También se logró obtener una escalabilidad lineal del tiempo de ejecución con respecto al tamaño de la matriz espacial utilizada y también con respecto a la cantidad de iteraciones temporales de la simulación.UCR::Vicerrectoría de Investigación::Sistema de Estudios de Posgrado::Ingeniería::Maestría Académica en Computación e Informátic