Title: Real and complex valued geometrical optics inverse ray-tracing for inline field calculations

Abstract

In this work, a 3-D ray based model for computing laser fields in dissipative and amplifying media is presented. The eikonal equation is solved using inverse ray-tracing on a dedicated nonstructured 3-D mesh. Inverse ray-tracing opens the possibility of using Complex Geometrical Optics (CGO), for which we propose a propagation formalism in a finite element mesh. Divergent fields at caustics are corrected using an etalon integral method for fold-type caustics. This method is successfully applied in dissipative media by modifying the ray-ordering and root selection rules, thereby allowing one to reconstruct the field in the entire caustic region. In addition, we demonstrate how caustics in the CGO framework can disappear entirely for sufficiently dissipative media, making the complex ray approach valid in the entire medium. CGO is shown to offer a more precise modeling of laser refraction and absorption in a dissipative medium when compared to Geometrical Optics (GO). In the framework of Inertial Confinement Fusion (ICF), this occurs mostly at intermediate temperatures or at high temperatures close to the critical density. Additionally, GO is invalid at low temperatures if an approximated expression of the permittivity is used. The inverse ray-tracing algorithm for GO and CGO is implemented in themore » IFRIIT code, in the framework of a dielectric permittivity described in 3-D using a piecewise linear approximation in tetrahedrons. Fields computed using GO and CGO are compared to results from the electromagnetic wave solver LPSE. Excellent agreement is obtained in 1-D linear and nonlinear permittivity profiles. Good agreement is also obtained for ICF-like Gaussian density profiles in 2-D. Finally, we demonstrate how the model reproduces Gaussian beam diffraction using CGO. The IFRIIT code will be interfaced inline to 3-D radiative hydrodynamic codes to describe the nonlinear laser plasma interaction in ICF and high-energy-density plasmas.« less

Authors:

Colaïtis, A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-4913-1653"
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Palastro, J. P.  ^[1];

• Search DOE PAGES for author "Palastro, J. P."
• Search DOE PAGES for ORCID "0000-0002-6721-1924"
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Follett, R. K. ^[1]; Igumenschev, I. V.  ^[1];

• Search DOE PAGES for author "Igumenschev, I. V."
• Search DOE PAGES for ORCID "0000-0001-5495-8503"
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Goncharov, V. ^[1]

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+ Show Author Affiliations

1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics

Publication Date:

2019-03-01

Research Org.:

Univ. of Rochester, NY (United States). Lab. for Laser Energetics

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

Contributing Org.:

Univ. of Rochester, NY (United States). Lab. for Laser Energetics

OSTI Identifier:

1505766

Report Number(s):

2018-307; 1481
Journal ID: ISSN 1070-664X; 2018-308, 1481, 2440

Grant/Contract Number:  

NA0003856

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 26; Journal Issue: 3; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY