Tomographic Reconstruction of Magnetic Field structures from Proton Radiography Data*

We present recent progress in our development of techniques and algorithms used to recover spatially-resolved magnetic field structures from measurements made using the proton radiography diagnostic. The nature of proton radiography places severe limitations on the angular resolution achievable by tomographic measurements, due to space constraints in the target chamber as well as the difficulty of simultaneously producing many suitable proton beams; we investigate the effectiveness of real-space regularisation and Fourier-domain inpainting techniques to avoid the severe artefacts usually associated with reconstruction of sparse-view tomographic data.

Finally, we demonstrate the full reconstruction process, from particle-in-cell derived magnetic fields to synthetic proton radiographs, then to line-integrated magnetic fields recovered from raw radiographs using the Monge-Ampère formalism and finally to a single spatially-resolved magnetic field component.