Stable Beam Propagation for Efficient MeV Photon Dose Generation in Laser–Solid Interactions
ORAL
Abstract
Analytical and numerical models indicate that x-ray dose ∝ (Iλ2)1/2 in intense lasers-solid interactions. Empirically, alignment with these predictions has been observed up to 3 x 1019 W/cm2. Leveraging the OMEGA-EP short-pulse beam, we not only extended this scaling to 3 x 1020 W/cm2 but also produced unprecedented doses-4.7 and 5.4 rad in air at 1 m-for Ephoton > 100 keV at 511 J and 972 J with a pulse duration of 0.5 ps and 5.8 ps, respectively. The efficiency of this process defies explanations based solely on operating at higher intensities. VPIC simulations, incorporating experimentally observed hotspots within the laser focus, unveiled stabilized propagation of the beam through 10s of microns pre-plasma. This stability, a balancing of self-focusing and density-induced defocusing, enhances the penetration of the overdense region through relativistic-induced-transparency (RIT), culminating in the acceleration of a larger volume of electrons.
*The experiment was conducted at the OMEGA Laser Facility at the University of Rochester's Laboratory for Laser Energetics and was performed under the auspices of the U.S. Department of Energy by Triad National Security, LLC, Los Alamos National Laboratory, under Contract No. 89233218CNA000001 and was supported by the Laboratory Directed Research and Development program. Computing resources were provided by the ATCC and LANL Institutional Computing programs. The work was further supported by the Department of Energy, National Nuclear Security Administration, under Award No. DE-NA0004147, as well as a UCOP LFRP fellowship under Award No. L23GF6264.
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Publication:Phys. Rev. Research 7, 023169 – Published 19 May, 2025
