Effect of target structure on the generation of MeV photons for short-pulse, laser-driven sources*

MeV radiography is a useful tool for imaging dense objects. Creating MeV photons using ultra-intense laser-matter interactions can potentially provide advantages over conventional accelerator methods such as shorter pulse lengths, total source footprint, and versatile pointing. While short pulse laser radiography has been demonstrated on several facilities, there have only been a limited number of target geometries that have been investigated [1,2]. We present the results of particle-in-cell simulations with a variety of targets that have several different types of structures, either solid or plasma.[3] An effective temperature for the hot-electron population for each target is obtained for simple flat targets [4] and structured target spectra are compared to this baseline. The electron spectrum is then used to calculate the X-ray Bremsstrahlung radiation spectrum for various target thicknesses. We report on the target structures that provide the greatest number of 1–5 MeV X-rays.

 

[1] C. Courtois, et al., Phys. Plasmas 16, 013105 (2009)

[2] S. Kerr, et al. Phys. of Plasmas. 30. 013101. (2023)

[3] A. J. Kemp, et al., Phys. Plasmas 28, 103102 (2021)

[4] K. Miller, et al., Phys. Rev. Research 5, L012044 (2023)