Publications

This is the user manual for EMPIRE, a simulation code for electromagnetics and plasma physics.

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This report describes the high-level accomplishments from the Plasma Science and Engineering Grand Challenge LDRD at Sandia National Laboratories. The Laboratory has a need to demonstrate predictive capabilities to model plasma phenomena in order to rapidly accelerate engineering development in several mission areas. The purpose of this Grand Challenge LDRD was to advance the fundamental models, methods, and algorithms along with supporting electrode science foundation to enable a revolutionary shift towards predictive plasma engineering design principles. This project integrated the SNL knowledge base in computer science, plasma physics, materials science, applied mathematics, and relevant application engineering to establish new cross-laboratory collaborations on these topics. As an initial exemplar, this project focused efforts on improving multi-scale modeling capabilities that are utilized to predict the electrical power delivery on large-scale pulsed power accelerators. Specifically, this LDRD was structured into three primary research thrusts that, when integrated, enable complex simulations of these devices: (1) the exploration of multi-scale models describing the desorption of contaminants from pulsed power electrodes, (2) the development of improved algorithms and code technologies to treat the multi-physics phenomena required to predict device performance, and (3) the creation of a rigorous verification and validation infrastructure to evaluate the codes and models across a range of challenge problems. These components were integrated into initial demonstrations of the largest simulations of multi-level vacuum power flow completed to-date, executed on the leading HPC computing machines available in the NNSA complex today. These preliminary studies indicate relevant pulsed power engineering design simulations can now be completed in (of order) several days, a significant improvement over pre-LDRD levels of performance.

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In this paper we present an adjustment to traditional ALE discretizations of resistive MHD where we do not neglect the time derivative of the electric displacement field. This system is referred to variously as a perfect electromagnetic fluid or a single fluid plasma although we refer to the system as Full Maxwell Hydrodynamics (FMHD) in order to evoke its similarities to resistive Magnetohydrodynamics (MHD). Unlike the MHD system the characteristics of this system do not become arbitrarily large in the limit of low densities. In order to take advantage of these improved characteristics of the system we must tightly couple the electromagnetics into the Lagrangian motion and do away with more traditional operator splitting. We provide a number of verification tests to demonstrate both accuracy of the method and an asymptotic preserving (AP) property. In addition we present a prototype calculation of a Z-pinch and find very good agreement between our algorithm and resistive MHD. Further, FMHD leads to a large performance gain (approximately 4.6x speed up) compared to resistive MHD. We unfortunately find our proposed algorithm does not conserve charge leaving us with an open problem.

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