Scaling for ultrashort pulse amplification in plasma via backward Raman amplification scheme operating in the short wavelength regime

Abstract

The applicability of extreme ultraviolet (XUV) and soft x-ray radiation sources in a resonant backward Raman amplification (BRA) scheme in amplifying the weak ultrashort sub-femtosecond pulses has been examined. Utilizing the slowly-varying-envelope-approximation-based analytical expressions for the resonant three-wave interaction along with viable physics constraint, a parameter space configuring the laser/plasma features required to achieve significant pulse amplification and compression has been derived. A specific parametric configuration for resonant BRA operation in the short wavelength regime has been identified and validated using particle in cell simulation results. The outcome predicts that the resonant BRA scheme may efficiently be applied to amplify the weak pulses for the pump radiation operating within the XUV regime; the effect may be optimized via efficient tuning of the plasma density, pump pulse intensity, and wavelength of the interacting waves. As an illustration, resonant BRA scheme in reference to a DESY FLASH XUV laser source has been conceptualized, and a competent set of laser/plasma parameters in achieving significant amplification is configured. The limitations and plausible rectification for a practical execution of the resonant BRA have also been discussed.