Production of electron-positron pairs by intense laser pulses in an overdense plasma

We consider the production of electron-positron (e-p) pairs by circularly polarized intense laser pulses impinging onto a slightly overdense electron-ion plasma. For this purpose, we numerically solve one-dimensional system of Maxwell and relativistic two fluid equations. The production of e-p pairs is possible due to the regular motion of relativistic electrons in the field of plasma ions (trident process). The highest rate of e-p pair production is observed at the early stage of laser-plasma interactions when the ion plasma density modification is small. However, effects related to the ion motion reduces the efficiency of the pair creation. Furthermore, it is found that, in contrast to the case of a strongly overdense plasma, in a slightly over-critical plasma double-sided illumination of a thin plasma target by intense laser beams does not lead to an effective creation of e-p pairs. (c) 2006 Elsevier B.V. All rights reserved.