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In this paper we discuss numerical methods and algorithms for the solution of NLTE stellar atmosphere problems involving expanding atmospheres, e.g., found in novae, supernovae and stellar winds. We show how a scheme of nested iterations…

Astrophysics · Physics 2011-06-02 P. H. Hauschildt , E. Baron

We propose a super-resolution quantum lithography scheme based on coherent population trapping in lambda-type atoms coupled to temporally-cascaded standing-wave driving fields. By realizing effective multiplication of optical intensity…

Quantum Physics · Physics 2008-08-19 Hee Su Park , Sun Kyung Lee

Energy resolved neutron imaging (ERNI) is an advanced neutron radiography technique capable of non-destructively extracting spatial isotopic information within a given material. Energy-dependent radiography image sequences can be created by…

Image and Video Processing · Electrical Eng. & Systems 2021-10-07 Thilo Balke , Alexander M. Long , Sven C. Vogel , Brendt Wohlberg , Charles A. Bouman

Aims. We present a new radiation hydrodynamics code, called "ARK-RT" which uses a two-moment model with the M1 closure relation for radiative transfer. This code aims at being ready for high-performance computing, on exascale architectures.…

Instrumentation and Methods for Astrophysics · Physics 2021-02-24 H. Bloch , P. Tremblin , M. González , T. Padioleau , E. Audit

We numerically study fast Newtonian radiation mediated shocks (RMS - v/c~0.2) in two simplified problems in the context of supernova shock breakout; (1) An RMS traveling in a uniform medium, and (2) an RMS escaping a powerlaw density…

High Energy Astrophysical Phenomena · Physics 2026-04-14 Jonathan Morag

In astrophysical systems, radiation-matter interactions are important in transferring energy and momentum between the radiation field and the surrounding material. This coupling often makes it necessary to consider the role of radiation…

High Energy Astrophysical Phenomena · Physics 2012-08-28 U. M. Noebauer , S. A. Sim , M. Kromer , F. K. Roepke , W. Hillebrandt

Increasing main sequence stellar luminosity with stellar mass leads to the eventual dominance of radiation pressure in stellar envelope hydrostatic balance. As the luminosity approaches the Eddington limit, additional instabilities (beyond…

Solar and Stellar Astrophysics · Physics 2022-01-12 William C. Schultz , Lars Bildsten , Yan-Fei Jiang

Atomic layer deposition (ALD), a layer-by-layer controlled method to synthesize ultrathin materials, provides various merits over other techniques such as precise thickness control, large area scalability and excellent conformality. Here we…

We present a numerical method for solving the time-independent thermal radiative transfer (TRT) equation or the neutron transport (NT) equation when the opacity or cross-section varies rapidly in energy (frequency). The approach is based on…

Numerical Analysis · Mathematics 2016-12-21 T. S. Haut , C. Ahrens , A. Jonko , R. Lowrie , A. Till

To investigate inelastic electron scattering, which is ubiquitous in various fields of study, we carry out ab initio study of the real-time dynamics of a one-dimensional electron wave packet scattered by a hydrogen atom using different…

Atomic Physics · Physics 2020-06-24 Yeonghun Lee , Xiaolong Yao , Massimo V. Fischetti , Kyeongjae Cho

We introduce the RHDLPP, a flux-limited multigroup radiation hydrodynamics numerical code designed for simulating laser-produced plasmas in diverse environments. The code bifurcates into two packages: RHDLPP-LTP for low-temperature plasmas…

The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial…

Numerical Analysis · Mathematics 2014-03-05 Bobby Philip , Zhen Wang , Mark Berrill , Manuel Rodriguez Rodriguez , Michael Pernice

We propose an efficient, robust, Lagrangian (characteristic-based) transport solver for the time-dependent thermal radiative Transfer (TRT) applications within the context of a moment-accelerated (High-Order/Low-Order, HOLO) algorithm. This…

Computational Physics · Physics 2019-05-01 H. Park , L. Chacon , A. Matsekh , G. Chen

The space-time adaptive ADER-DG finite element method with LST-DG predictor and a posteriori sub-cell ADER-WENO finite-volume limiting was used for simulation of multidimensional reacting flows with detonation waves. The presented numerical…

Fluid Dynamics · Physics 2024-09-23 I. S. Popov

A Monte Carlo code (ARTIS) for modelling time-dependent three-dimensional spectral synthesis in chemically inhomogeneous models of Type Ia supernova ejecta is presented. Following the propagation of gamma-ray photons, emitted by the…

High Energy Astrophysical Phenomena · Physics 2014-11-20 M. Kromer , S. A. Sim

We present a novel ray acceleration structure for radiative transfer outside of local thermodynamic equilibrium (non-LTE), leveraging techniques from computer graphics to improve computational efficiency. By applying mipmapping (local…

Instrumentation and Methods for Astrophysics · Physics 2025-11-12 Christopher M. J. Osborne

We construct and justify leading order weakly nonlinear geometric optics expansions for nonlinear hyperbolic initial value problems, including the compressible Euler equations. The technique of simultaneous Picard iteration is employed to…

Analysis of PDEs · Mathematics 2012-07-18 Matthew Hernandez

Radiative transfer and radiation hydrodynamics use the relativistic Boltzmann equation to describe the kinetics of photons. It is difficult to solve the six-dimensional time-dependent transfer equation unless the problem is highly symmetric…

Instrumentation and Methods for Astrophysics · Physics 2011-02-09 Chi-kwan Chan

We consider the inverse problem of fitting atmospheric dispersion parameters based on time-resolved back-scattered differential absorption Lidar (DIAL) measurements. The obvious advantage of light-based remote sensing modalities is their…

Analysis of PDEs · Mathematics 2023-08-01 Robert Lung , Nick Polydorides

We develop the generalized rotating-wave approximation (GRWA) approach (Phys. Rev. Lett. 99, 173601 (2007)) to study the single-photon scattering on a two-level system (TLS) with arbitrarily strong coupling to a local mode in a…

Quantum Physics · Physics 2012-12-03 Z. H. Wang , Yong Li , D. L. Zhou , Chang-pu Sun , Peng Zhang