FPEOS: A First-Principles Equation of State Table of Deuterium for Inertial Confinement Fusion Applications

TL;DR

This paper presents a first-principles equation of state (EOS) table for deuterium derived from path-integral Monte Carlo simulations, improving the accuracy of ICF implosion modeling under degenerate plasma conditions.

Contribution

The authors develop a new first-principles EOS table for deuterium using PIMC simulations, covering a wide range of conditions relevant to inertial confinement fusion.

Findings

FPEOS shows discrepancies with SESAME and Kerley03 tables at certain plasma conditions.

Kerley03 aligns better with FPEOS than SESAME across many conditions.

Hydrodynamics simulations with FPEOS and Kerley03 yield similar results, differing from SESAME.

Abstract

Understanding and designing inertial confinement fusion (ICF) implosions through radiation-hydrodynamics simulations rely on the accurate knowledge of the equation of state (EOS) of the deuterium and tritium fuels. To minimize the drive energy for ignition, the imploding shell of DT fuel must be kept as cold as possible. Such low-adiabat ICF implosions can access to coupled and degenerate plasma conditions, in which the analytical or chemical EOS models become inaccurate. Using the path-integral Monte Carlo (PIMC) simulations we have derived a first-principles EOS (FPEOS) table of deuterium that covers typical ICF fuel conditions at densities ranging from 0.002 to 1596 g/cm3 and temperatures of 1.35 eV to 5.5 keV. We report the internal energy and the pressure, and discuss the structure of the plasma in terms of pair-correlation functions. When compared with the widely used SESAME table and the revised Kerley03 table, discrepancies in the internal energy and in the pressure are identified for moderately coupled and degenerate plasma conditions. In contrast to the SESAME table, the revised Kerley03 table is in better agreement with our FPEOS results over a wide range of densities and temperatures. Although subtle differences still exist for lower temperatures (T < 10 eV) and moderate densities (1 to 10 g/cc), hydrodynamics simulations of cryogenic ICF implosions using the FPEOS table and the Kerley03 table have resulted in similar results for the peak density, areal density ({\rho}R), and neutron yield, which are significantly different from the SESAME simulations.