Relativistic Modeling Capabilities in Perseus Extended MHD Simulation Code for HED Plasmas
Abstract
This project is submitted in response to DEFOA0001153, and will be carried out by Dr. Charles Seyler and Dr. Nathaniel Hamlin as post doc under the direction of Professor Seyler. The objectives are to enable PERSEUS to selfconsistently model relativistic highenergydensity (HED) laboratory and astrophysical phenomena. Electrons and ions in a plasma are generally modeled either as fluids using a twofluid code, like PERSEUS, or as particles using a ParticleIn Cell (PIC) code. Nonrelativistic PERSEUS solves the twofluid equations, formulated in terms of a generalized Ohm’s law (GOL), so as to model about nine orders of magnitude in density variation using a local semiimplicit method. Relativistic PERSEUS preserves this structure and therefore retains these advantageous properties, enabling it to model a broader range of relativistic HED phenomena than previous codes. We have also overcome a major technical challenge associated with solving a relativistic system of equations relating conserved quantities (momentum, energy, etc.) to primitive variables (density, velocity, and pressure). We have thus far developed a relativistic version of PERSEUS and demonstrated that it recovers expected nonrelativistic results. We are currently using relativistic PERSEUS to model two HED phenomena, namely laserplasma interactions and Xpinches, both of which show spectroscopic evidence ofmore »
 Authors:

 Cornell Univ., Ithaca, NY (United States)
 Publication Date:
 Research Org.:
 Cornell Univ., Ithaca, NY (United States)
 Sponsoring Org.:
 USDOE National Nuclear Security Administration (NNSA)
 OSTI Identifier:
 1482335
 Report Number(s):
 DESC0014341
 DOE Contract Number:
 SC0014341
 Resource Type:
 Technical Report
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Relativistic plasma; highenergy density; numerical simulation
Citation Formats
Seyler, Charles E. Relativistic Modeling Capabilities in Perseus Extended MHD Simulation Code for HED Plasmas. United States: N. p., 2018.
Web. doi:10.2172/1482335.
Seyler, Charles E. Relativistic Modeling Capabilities in Perseus Extended MHD Simulation Code for HED Plasmas. United States. doi:10.2172/1482335.
Seyler, Charles E. Fri .
"Relativistic Modeling Capabilities in Perseus Extended MHD Simulation Code for HED Plasmas". United States. doi:10.2172/1482335. https://www.osti.gov/servlets/purl/1482335.
@article{osti_1482335,
title = {Relativistic Modeling Capabilities in Perseus Extended MHD Simulation Code for HED Plasmas},
author = {Seyler, Charles E.},
abstractNote = {This project is submitted in response to DEFOA0001153, and will be carried out by Dr. Charles Seyler and Dr. Nathaniel Hamlin as post doc under the direction of Professor Seyler. The objectives are to enable PERSEUS to selfconsistently model relativistic highenergydensity (HED) laboratory and astrophysical phenomena. Electrons and ions in a plasma are generally modeled either as fluids using a twofluid code, like PERSEUS, or as particles using a ParticleIn Cell (PIC) code. Nonrelativistic PERSEUS solves the twofluid equations, formulated in terms of a generalized Ohm’s law (GOL), so as to model about nine orders of magnitude in density variation using a local semiimplicit method. Relativistic PERSEUS preserves this structure and therefore retains these advantageous properties, enabling it to model a broader range of relativistic HED phenomena than previous codes. We have also overcome a major technical challenge associated with solving a relativistic system of equations relating conserved quantities (momentum, energy, etc.) to primitive variables (density, velocity, and pressure). We have thus far developed a relativistic version of PERSEUS and demonstrated that it recovers expected nonrelativistic results. We are currently using relativistic PERSEUS to model two HED phenomena, namely laserplasma interactions and Xpinches, both of which show spectroscopic evidence of relativistic electrons. In an Xpinch, a section of wire carrying sufficiently large current forms a plasma column that pinches down to a pointlike source, generating Xrays for use in radiographic imaging. Laserplasma interactions have been simulated using PIC codes, and we use their results as a benchmark for comparison. However, neither PIC codes nor existing twofluid schemes can simulate Xpinches, due to the broad range of densities which have thus far made such a simulation computationally prohibitive. In both laserplasma interaction and Xpinch simulations, we have observed relativistic phenomena that PERSEUS could not previously model. This includes relativistic channeling of a laser into an overdense deuterium gas (i.e. induced transparency), consistent with PIC simulation results, along with energetic electrons and ions following an Xpinch and likely accompanied by strong Xray emission, consistent with experimental observations of energetic Xrays. This proposal includes our latest simulation results. We will improve computational efficiency with techniques that allow the use of a less refined numerical grid. This will enable extensions to threedimensional geometries. We will improve modeling of laserplasma interactions and Xpinches, including radiative transport processes, in order to improve comparisons with PIC simulations and experimental diagnostics. We will also model power loss through electrode surface plasmas in magnetically insulated transmission lines (MITLs). We will model relativistic astrophysical phenomena in both astrophysical and HED regimes, which could shed light on the validity of laboratory astrophysics for certain problems. These phenomena are currently modeled using PIC codes and existing relativistic twofluid codes, neither of which can model the range of length scales of which relativistic PERSEUS is capable. There is strong potential for this project to have a broad impact on both the astrophysical and laboratory plasma communities. In the laboratory community, our work is applicable to those concerned with laserplasma interactions such as laserdriven fusion, and those in the dense Z pinch community concerned with Xpinches and electrode surface plasmas. An improved understanding of the mechanisms of hard (i.e. highenergy) Xray generation will likely make important contributions toward the use of Xpinches for radiography through the harnessing or mitigation of hard Xrays, depending on the application. The modeling of electrode surface plasmas, including vacuum electron flow, will improve our understanding of power loss to various loads.},
doi = {10.2172/1482335},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {11}
}