Optimizing electron-positron pair production on kilojoule-class high-intensity lasers for the purpose of pair-plasma creation

Expressions for the yield of electron-positron pairs, their energy spectra, and production rates have been obtained in the interaction of multi-kJ pulses of high-intensity laser light interacting with solid targets. The Bethe-Heitler conversion of hard x-ray bremsstrahlung [ D. A. Gryaznykh, Y. Z. Kandiev and V. A. Lykov JETP Lett. 67 257 (1998); K. Nakashima and H. Takabe Phys. Plasmas 9 1505 (2002)] is shown to dominate over direct production (trident process) [ E. P. Liang, S. C. Wilks and M. Tabak Phys. Rev. Lett. 81 4887 (1998)]. The yields and production rates have been optimized as a function of incident laser intensity by the choice of target material and dimensions, indicating that up to 5×10¹¹ pairs can be produced on the OMEGA EP laser system [ L. J. Waxer et al. Opt. Photonics News 16 30 (2005)]. The corresponding production rates are high enough to make possible the creation of a pair plasma.