Enabling the Realisation of Proton Tomography

Proton radiography is a widely-fielded diagnostic used to measure magnetic structures in plasma. The deflection of protons with multi-MeV kinetic energy by the magnetic fields is used to infer the path-integrated field strength, but extracting three-dimensional information has proven to be challenging. In this Letter, a new method for production of multiple spatially independent proton beams from a single laser-irradiated foil target is proposed. It is shown, via two-dimensional particle-in-cell simulations, that the irradiation of a 'laser' foil, connected by conductive wires to several secondary 'beam' foil targets, provides proton beams with the excellent fidelity required for proton probing. This novel target geometry allows for flexible positioning and direction of a number of 'beam' foils, thereby greatly improving the prospects of three-dimensional tomographic reconstruction of magnetic fields for high energy density physics studies which benefit from the largest possible number of view angles.