Kα emission and secondary electrons in femtosecond laser target interactions

Abstract

This paper deals with the contribution of secondary electron emission, produced during the slowing down of fast electrons, on the intensity and temporal shape of the generated Kα pulse. The problem is treated in a general manner emphasizing laser–plasma interactions, where it was suggested in the literature that these electrons could play an important role on the temporal duration. Here, we make use of a hybrid model which includes secondary emission in conjunction with the continuous slowing down approximation (CSDA). The results are compared with those obtained from a simple CSDA calculation, with no detailed accounting of secondary emission and without straggling. Secondary electrons were calculated to contribute up to an additional 20% to the total Kα yield and in the case of monoenergetic electron beams in thick targets also to influence the temporal shape. The pulse duration is not affected in a significant manner by the secondary electrons.