Development of a bright MeV photon source with compound parabolic concentrator targets on the National Ignition Facility Advanced Radiographic Capability (NIF-ARC) laser
S. Kerr, D. Rusby, G. J. Williams, K. D. Meaney, D. J. Schlossberg, A. Aghedo, D. Alessi, J. Ayers, S.M. Azhar, Maurice B. Aufderheide, M. W. Bowers, J. Bude, Hui Chen, Ginevra Cochran, John K. Crane, J. M. Di Nicola, D. N. Fittinghoff, P. Fitzsimmons, Hermann Geppert-Kleinrath, B. Golick, G. P. Grim, A. Haid, M. Hamamoto, R. Heredia, M. R. Hermann, S. Herriot, M. P. Hill, W. Hoke, D. H. Kalantar, A. Kemp, Y. Kim, K. N. LaFortune, N. Lemos, A. Link, R. Lowe-Webb, A. G. MacPhee, M. J.-E. Manuel, D. Martinez, M. Mauldin, S. Patankar, L. Pelz, M. Prantil, M. Quinn, C. W. Siders, S. Vonhof, Paul J. Wegner, S. C. Wilks, Wade H. Williams, K. P. Youngblood, A. J. Mackinnon
Abstract
Compound parabolic concentrator (CPC) targets are utilized at the National Ignition Facility Advanced Radiographic Capability (NIF-ARC) laser to enhance the acceleration of electrons and production of high energy photons, for laser durations of 10 ps and energies up to 2.4 kJ. A large enhancement of mean electron energy (>2 ×) and photon brightness (>10×) is found with CPC targets compared to flat targets. Using multiple diagnostic techniques at different spatial locations and scaling by gold activation spatial data, photon spectra are characterized for Ephoton=0.5–30 MeV. Beam width and pointing variations are given. The efficient production of MeV photons at Ilaser≈2×1018 W/cm2 with CPCs is observed, with doses of >10 rad in air at 1 m for Ephoton>0.5 MeV; these exceed those previously reported with laser-driven sources. Using this source, sub-mm resolution radiographs are generated through large areal density radiograph objects. These results are promising for the development of bright MeV x-ray and particle sources on Petawatt class laser systems.