Analyzing Proton Radiographs for Magnetized HED Plasma Experiments with an In-Situ X-ray Reference

Developing precise methods for the measurement of magnetic fields is an important tool for understanding the interactions of magnetic fields and magnetized high energy density (HED) plasmas relevant to laboratory astrophysics and magnetized fusion schemes. We report a novel technique of proton radiography that was developed and implemented to precisely measure non-uniform magnetic fields in HED plasma at the Omega laser facility. A DHe3 capsule is used to produce both protons and intense x-rays. By placing a mesh grid between the capsule and plasma, the proton beam is split into smaller beamlets, which are deflected by the plasma's electromagnetic fields to a detector stack. The detector stack consists of two CR39 plates for measuring deflections of 3 and 15 MeV protons and an X-ray image plate for an absolute reference of undeflected beamlets. In this work, automated algorithms for calculating beamlet deflections are developed to construct a 2D map of magnetic fields. This analysis is applied to HEDP experiments for plasmas expanding into a background magnetic field and magnetic reconnection experiments of two colliding plasmas.