Characterization of Plasma for Raman Amplification

As the frontier of high-intensity lasers advances, the need for more efficient and damage-resistant compression gratings has become a significant cost and size constraint for advanced laser systems. Plasma-based amplifiers, which utilize a plasma's ability to sustain intensities orders of magnitude larger than traditional gratings, offer an alternative solution to the constraints of these gratings. Such plasma amplifiers utilize Raman amplification, a process in which stimulated Raman scattering (SRS) transfers energy from a long (~ns) pump pulse to a counter-propagating short (~100-fs) seed pulse through a resonantly driven electron plasma wave. However, depending on local plasma characteristics, namely the temperature and density, many phenomena can limit this process. Thermal variation within the plasma can lead to spontaneous SRS, detuning of the resonant plasma frequency, and shifts to the wave-breaking limit, all of which can lead to early or incomplete pump depletion. As such, careful characterization of the plasma parameter space is required to optimize Raman amplification. We will present the density and temperature characterization of plasmas for Raman amplification studies via density measurements and theory comparisons.