Characterizing laser-based MeV radiographic capability at NIF-ARC.
ORAL
Abstract
X-ray radiography of high-areal density objects is desirable for many applications. During high-energy laser-solid interactions (\textgreater 1 x 10$^{\mathrm{18}}$ W/cm$^{\mathrm{2}})$, a population of hot-electrons are accelerated to mega-electron volt energies. Injecting this population into a high-Z, high-density converter creates a similarly high-energy x-ray beam via bremsstrahlung. These x-rays have been shown to have a small source size (100s $\mu $m), high dose (several Rad) and high temperature (\textgreater 1 MeV)[1]. We've performed experiments on NIF-ARC to benchmark the photon spectra. Diagnosing the x-ray spectrum in this regime is difficult due to low interaction cross sections. We have used a suite of complimentary diagnostics, such as photo-nuclear activation and absorption spectrometers, to reconstruct the spectrum. These experiments at NIF ARC have shown that the temperature of these x-rays is on the order of several MeV.
*This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the LLNL LDRD program under tracking code 19-SI-002. IM:LLNL-ABS-780210
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