SASE in plasmas: Analysis and simulation of Raman backscatter from noise

Abstract

Theoretical techniques from free-electron laser research are modified for analytical and numerical investigations of Raman Backscatter (RBS) in plasmas. The physical system consists of an intense short laser pulse propagating through an underdense plasma. The analogy with the free-electron laser is essentially a correspondence of the plasma electrons with the electron beam, the incident laser pulse with the wiggler and the backscatter pulse with the radiation. This approach has significant advantages over previous theoretical treatments, which were mostly linear fluid theories, and particle-in-cell simulations which are computationally expensive. The problem of backscatter from noise, which is the RBS equivalent of SASE, is analyzed and compared to experimental observations.