Proton radiography of electromagnetic fields in laser-driven plasmas using Imaging Plates.

A new detector design has been fielded on the Omega-60 laser facility using a DHe-3 backlighter capsule to radiograph a magnetized experiment. DHe-3 capsules produce a low flux (~10⁸ yield in 4π) of protons requiring detectors with close-to single-particle sensitivity to be employed [1]. The new detector stack consisted of both imaging plate (IP) and CR-39 to detect 14.7 MeV protons where, historically, only CR-39 has been used [2,3]. IP is sensitive to significant contributions in signal from both x-rays and protons so additional filtering has to be added to attenuate the x-rays. The signals and features observed from a single shot are detected by both IP and CR-39, giving confirmation that it is protons creating the signatures on the IP. A large benefit to this new stack design is that IP can be scanned and processed on much faster timescales than CR-39 allowing for prompt shot feedback. Results from recent experiments investigating magnetised, collisionless shocks as well as plasmas being driven out into hohlraum-like gas fills have utilized this detector and results from these platforms will be presented.

[1] E. R. Tubman et al., NIM 1060 (2024)

[2] C. K. Li et al., PRL 97 (2006)

[3] C. K. Li et al., PRL 99 (2007)