## First-principles investigations on ionization and thermal conductivity of polystyrene for inertial confinement fusion applications

## Abstract

Using quantum molecular-dynamics (QMD) methods based on the density functional theory, we have performed first-principles investigations on the ionization and thermal conductivity of polystyrene (CH) over a wide range of plasma conditions (ρ = 0.5 to 100 g/cm ^{3} and T = 15,625 to 500,000 K). The ionization data from orbital-free molecular-dynamics calculations have been fitted with a “Saha-type” model as a function of the CH plasma density and temperature, which exhibits the correct behaviors of continuum lowering and pressure ionization. The thermal conductivities (κ _{QMD}) of CH, derived directly from the Kohn–Sham molecular-dynamics calculations, are then analytically fitted with a generalized Coulomb logarithm [(lnΛ) _{QMD}] over a wide range of plasma conditions. When compared with the traditional ionization and thermal conductivity models used in radiation–hydrodynamics codes for inertial confinement fusion simulations, the QMD results show a large difference in the low-temperature regime in which strong coupling and electron degeneracy play an essential role in determining plasma properties. Furthermore, hydrodynamic simulations of cryogenic deuterium–tritium targets with CH ablators on OMEGA and the National Ignition Facility using the QMD-derived ionization and thermal conductivity of CH have predicted –20% variation in target performance in terms of hot-spot pressure and neutron yield (gain)more »

- Authors:

- Univ. of Rochester, Rochester, NY (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Publication Date:

- Research Org.:
- Univ. of Rochester, Rochester, NY (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1255551

- Alternate Identifier(s):
- OSTI ID: 1247602; OSTI ID: 1408831

- Report Number(s):
- LA-UR-15-29300

Journal ID: ISSN 1070-664X; 2015-199; TIC-1269

- Grant/Contract Number:
- NA0001944; AC52-06NA25396

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physics of Plasmas

- Additional Journal Information:
- Journal Volume: 23; Journal Issue: 4; Journal ID: ISSN 1070-664X

- Publisher:
- American Institute of Physics (AIP)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; inertial confinement; plasma ionization; ionization; plasma temperature; thermal conductivity

### Citation Formats

```
Hu, S. X., Collins, Lee A., Goncharov, V. N., Kress, Joel David, McCrory, R. L., and Skupsky, S. First-principles investigations on ionization and thermal conductivity of polystyrene for inertial confinement fusion applications. United States: N. p., 2016.
Web. doi:10.1063/1.4945753.
```

```
Hu, S. X., Collins, Lee A., Goncharov, V. N., Kress, Joel David, McCrory, R. L., & Skupsky, S. First-principles investigations on ionization and thermal conductivity of polystyrene for inertial confinement fusion applications. United States. doi:10.1063/1.4945753.
```

```
Hu, S. X., Collins, Lee A., Goncharov, V. N., Kress, Joel David, McCrory, R. L., and Skupsky, S. Thu .
"First-principles investigations on ionization and thermal conductivity of polystyrene for inertial confinement fusion applications". United States. doi:10.1063/1.4945753. https://www.osti.gov/servlets/purl/1255551.
```

```
@article{osti_1255551,
```

title = {First-principles investigations on ionization and thermal conductivity of polystyrene for inertial confinement fusion applications},

author = {Hu, S. X. and Collins, Lee A. and Goncharov, V. N. and Kress, Joel David and McCrory, R. L. and Skupsky, S.},

abstractNote = {Using quantum molecular-dynamics (QMD) methods based on the density functional theory, we have performed first-principles investigations on the ionization and thermal conductivity of polystyrene (CH) over a wide range of plasma conditions (ρ = 0.5 to 100 g/cm3 and T = 15,625 to 500,000 K). The ionization data from orbital-free molecular-dynamics calculations have been fitted with a “Saha-type” model as a function of the CH plasma density and temperature, which exhibits the correct behaviors of continuum lowering and pressure ionization. The thermal conductivities (κQMD) of CH, derived directly from the Kohn–Sham molecular-dynamics calculations, are then analytically fitted with a generalized Coulomb logarithm [(lnΛ)QMD] over a wide range of plasma conditions. When compared with the traditional ionization and thermal conductivity models used in radiation–hydrodynamics codes for inertial confinement fusion simulations, the QMD results show a large difference in the low-temperature regime in which strong coupling and electron degeneracy play an essential role in determining plasma properties. Furthermore, hydrodynamic simulations of cryogenic deuterium–tritium targets with CH ablators on OMEGA and the National Ignition Facility using the QMD-derived ionization and thermal conductivity of CH have predicted –20% variation in target performance in terms of hot-spot pressure and neutron yield (gain) with respect to traditional model simulations.},

doi = {10.1063/1.4945753},

journal = {Physics of Plasmas},

number = 4,

volume = 23,

place = {United States},

year = {2016},

month = {4}

}

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