Pulse width effects on Raman backward laser amplification

Abstract

The effects of the longitudinal pulse width were studied in Raman backward amplification (RBA) of laser pulses in plasmas. In RBA systems, which utilize Raman backscatter in plasmas, it is generally required that a long pump laser pulse, whose longitudinal pulse duration is typically tens of picoseconds, propagates more than a few millimetres of gas jet or capillary plasmas. However, from the experimental point of view, a short propagation distance of the pump pulse is more desirable to avoid various technical difficulties and physical instabilities. In this paper, the change in the characteristics of RBA systems for varying widths of the pump pulse is studied by fluid and kinetic simulations. The effects of the initial width of the seed pulse are also addressed.