Mitigation Of Self-Focusing In Thomson Scattering Experiments

A fundamental challenge associated with measuring Thomson scattering comes from the small scattering cross section associated with the interaction. To improve photon statistics, a powerful Thomson-scattering probe laser is required. Ponderomotive self-focusing limits the maximum power in the Thomson-scattering probe and was shown to limit the maximum achievable Thomson-scattering signal-to-noise ratio. Operating the laser at powers above the self-focusing critical power was shown to cause beam degradation, which reduced the amount of collected Thomson-scattered light. Using a phase plate was shown to improve laser beam propagation and consequently improve the signal-to-noise ratio in the measured spectrum.