\textbf{A new tri-particle mono-energetic backlighting platform for the NIF and OMEGA}

Inertial-confinement-fusion and laboratory-astrophysical experiments involving lasers create high-energy-density plasmas that are of complex nature involving mixtures of ions, electrons, and electric/magnetic fields. Measurements play a critical role in providing quantitative information in these experiments, but several challenges with the current diagnostics remain to be addressed. Building on previous experience, a new DT$^{\mathrm{3}}$He tri-particle backlighter offers a unique capability, which has all the characteristic features of the D$^{\mathrm{3}}$He backlighter, but will substantially advance the capability for diagnosing strong fields and high density in HED plasmas on Omega and the NIF. Radiographs made with the 9.5-MeV deuterons, combined with 3-MeV DD-proton and 15-MeV D$^{\mathrm{3}}$He-proton radiographs, provide further energy constrains and a third time-of-flight delay, allowing discriminatory, high-quality radiographs of electric and magnetic fields and plasma matter to be recorded. Experiments for studying laser-driven, transit phenomena of HED plasmas, such as plasma transport and dynamics, as well as hydrodynamic/kinetic instabilities would greatly benefit from the additional time-resolved radiograph. This work was supported in part by the U.S. DOE, NLUF, LLE and LLNL.