Inferring Morphology and Strength of Magnetic Fields From Proton Radiographs
arXiv:1603.08617 · doi:10.1063/1.5013029
Abstract
Proton radiography is an important diagnostic method for laser plasma experiments, and is particularly important in the analysis of magnetized plasmas. The theory of radiographic image analysis has heretofore only permitted somewhat limited analysis of the radiographs of such plasmas. We furnish here a theory that remedies this deficiency. We show that to linear order in magnetic field gradients, proton radiographs are projection images of the MHD current along the proton trajectories. We demonstrate that in the linear approximation, the full structure of the perpedicular magnetic field can be reconstructed by solving a steady-state inhomogeneous 2-dimensional diffusion equation sourced by the radiograph fluence contrast data. We explore limitations of the inversion method due to Poisson noise, to discretization errors, to radiograph edge effects, and to obstruction by laser target structures. We also provide a separate analysis that is well-suited to the inference of isotropic-homogeneous magnetic turbulence spectra. We discuss extension of these results to the nonlinear contrast regime.
22 pages, 12 figures. Submitted to Physics of Plasmas
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Cited by in corpus (11)
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- Retrieving fields from proton radiography without source profiles
- Numerical Simulation of magnetized jet creation using a hollow ring of laser beams
- Proton deflectometry with in situ x-ray reference for absolute measurement of electromagnetic fields in high-energy-density plasmas
- Experimental observations of detached bow shock formation in the interaction of a laser-produced plasma with a magnetized obstacle
- MPRAD: A Monte Carlo and ray-tracing code for the proton radiography in high-energy-density plasma experiments
- Reconstructing magnetic deflections from sets of proton images using differential evolution
- Characterizing filamentary magnetic structures in counter-streaming plasmas by Fourier analysis of proton images
- Proton deflectometry analysis in magnetized plasmas: magnetic field reconstruction in one dimension