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(IF/P-05) Electron and Photon Production from Relativistic Laser-Plasma Interactions

E. Lefebvre¹⁾, M.M. Aléonard²⁾, J.F. Chemin²⁾, N. Cochet¹⁾, S. Darbon¹⁾, L. Disdier¹⁾, J. Faure³⁾, A. Fedotoff¹⁾, S. Fritzler⁴⁾, O. Landoas¹⁾, G. Malka²⁾, V. Malka⁴⁾, V. Méot¹⁾, P. Morel¹⁾, M. Rabec Le Gloahec¹⁾, C. Rousseaux¹⁾, A. Rouyer¹⁾, Ch. Rubbelynck¹⁾, V. Tikhonchuk⁴⁾, R. Wrobel¹⁾, P. Audebert^3)
 
1) Commissariat à l’Energie Atomique, DIF, Bruyères-le-Châtel, France
²⁾ CENBG, IN2P3-Université de Bordeaux 1, Gradignan, France
³⁾ LULI, Ecole Polytechnique, Palaiseau, France
⁴⁾ LOA, ENSTA-Ecole Polytechnique, Palaiseau, France

Abstract.  The interaction of short and intense laser pulses with plasmas is a very efficient source of relativistic electrons with tunable properties. In low density plasmas, we observed bunches of electrons up to 200 MeV, accelerated in the wake field of the laser pulse. Less energetic electrons (tens of MeV) have been obtained, albeit with a higher efficiency, during the interaction with a solid target. When these relativistic electrons slow down in a thick tungsten target, they emit very energetic Bremsstrahlung photons which have been diagnosed directly with photoconductors, and indirectly through photonuclear activation measurements. With the first method, a maximum dose of 80 mR at 1 m in air was measured, along the laser axis. Regarding the photonuclear measurement, up to 3.4 million photofission events have been diagnosed in a 238-U sample placed at the back of the target. The results are in reasonable agreement, over three orders of magnitude, with a model built on laser-plasma interaction and electron transport numerical simulations. They provide valuable insight on the electron acceleration and transport needed for fast ignition.

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