• Zahn, N.
• Kantsyrev, A.
• Bogdanov, A.
• Borisenko, N. G.
• Tavana, Parysatis
• Neumayer, P.
• Günther, M. M.
• Pukhov, A.
• Andreev, N. E.
• Gyrdymov, M.
• Consoli, Fabrizio
• Panyushkin, V.
• Popov, V. S.
• Rosmej, Olga N.
• Shen, X. F.
• Zähter, S.
• Skobliakov, A.

Abstract

e report on enhanced laser driven electron beam generation in the multi MeV energy range that promises a tremendous increase of the diagnostic potential of high energy sub-PW and PW-class laser systems. In the experiment, an intense sub-picosecond laser pulse of ∼10 19 Wcm −2 intensity propagates through a plasma of near critical electron density (NCD) and drives the direct laser acceleration (DLA) of plasma electrons. Low-density polymer foams were used for the production of hydrodynamically stable long-scale NCD-plasmas. Measurements show that relativistic electrons generated in the DLA-process propagate within a half angle of <?CDATA $1$?> 1 2 ± 1° to the laser axis. Inside this divergence cone, an effective electron temperature of 10–13 MeV and a maximum of the electron energy of 100 MeV were reached. The high laser energy conversion efficiency into electrons with energies above 2 MeV achieved 23% with a total charge approaching 1 μ C. For application purposes, we used the nuclear activation method to characterize the MeV bremsstrahlung spectrum produced in the interaction of the high-current relativistic electrons with high-Z samples and measured top yields of gamma-driven nuclear reactions. The optimization of the high-Z target geometry predicts an ultra-high MeV photon number of ∼10 12 per shot at moderate relativistic laser intensity of 10 19 Wcm −2 . A good agreement between the experimental data and the results of the 3D-PIC and GEANT4-simulations was demonstrated.

Topics

• density
• polymer
• energy density
• experiment
• simulation
• activation