arXiv subjects

D. D. Meyerhofer

Publications and source records attributed to D. D. Meyerhofer.

4 recordsLinked to original sources

arXiv2026

Observation of Self-Similarity in the Magnetic Fields Generated by the Ablative Nonlinear Rayleigh-Taylor Instability

Magnetic fields generated by the nonlinear Rayleigh-Taylor growth of laser-seeded three-dimensional broadband perturbations were measured in laser-accelerated planar targets using ultrafast proton radiography. The experimental data show self-similar behavior in the growing cellular magnetic field structures. These observations are consistent with a bubble competition and merger model that predicts the time evolution of the number and size of the bubbles, linking the cellular magnetic field structures with the Rayleigh-Taylor bubble and spike growth.

physics.plasm-ph↗

arXiv2025

Radiation-Hydrodynamics Effects in an Inhomogeneous Medium

Radiation flow through an inhomogeneous medium is critical in a wide range of physics and astronomy applications from transport across cloud layers on the earth to the propagation of supernova blast-waves producing UV and X-ray emission in supernovae. Radiation interacts with matter driving hydrodynamic feedback that further alters the radiation characteristics (energy and angular distribution). This paper reviews the current state of the art in the modeling of inhomogeneous radiation transport, subgrid models developed to capture this often-unresolved physics, and the experiments designed to improve our understanding of these models. This paper focuses on simulations based on upcoming experiments designed to test this physics. We present a series of detailed simulations (both single-clump and multi-clump conditions) probing the dependence on the physical properties of the radiation front (e.g. radiation energy) and material characteristics (specific heat, opacity, clump densities). We find that, unless the radiation pressure is high, the clumps will heat and then expand, effectively cutting off the radiation flow. The expanding winds can also produce shocks that generates high energy emission. We compare our detailed simulations with some of the current subgrid prescriptions, identifying some of the limitations of these current models.

astro-ph.IM↗

arXiv2015

Scaling the Yield of Laser-Driven Electron-Positron Jets to Laboratory Astrophysical Applications

We report new experimental results obtained on three different laser facilities that show directed laser-driven relativistic electron-positron jets with up to 30 times larger yields than previously obtained and a quadratic (~ E^2) dependence of the positron yield on the laser energy. This favorable scaling stems from a combination of higher energy electrons due to increased laser intensity and the recirculation of MeV electrons in the mm-thick target. Based on this scaling, first principles simulations predict the possibility of using such electron-positron jets, produced at upcoming high-energy laser facilities, to probe the physics of relativistic collisionless shocks in the laboratory.

physics.plasm-ph↗

arXiv2003

A Laboratory Investigation of Supersonic Clumpy Flows: Experimental Design and Theoretical Analysis

We present a design for high energy density laboratory experiments studying the interaction of hypersonic shocks with a large number of inhomogeneities. These ``clumpy'' flows are relevant to a wide variety of astrophysical environments including the evolution of molecular clouds, outflows from young stars, Planetary Nebulae and Active Galactic Nuclei. The experiment consists of a strong shock (driven by a pulsed power machine or a high intensity laser) impinging on a region of randomly placed plastic rods. We discuss the goals of the specific design and how they are met by specific choices of target components. An adaptive mesh refinement hydrodynamic code is used to analyze the design and establish a predictive baseline for the experiments. The simulations confirm the effectiveness of the design in terms of articulating the differences between shocks propagating through smooth and clumpy environments. In particular, we find significant differences between the shock propagation speeds in a clumpy medium compared to a smooth one with the same average density. The simulation results are of general interest for foams in both inertial confinement fusion and laboratory astrophysics studies. Our results highlight the danger of using average properties of inhomogeneous astrophysical environments when comparing timescales for critical processes such as shock crossing and gravitational collapse times.

astro-ph↗