Observation of the Langmuir decay instability driven by stimulated Raman scattering

Thomson scattering was used to measure the Langmuir wave spectrum driven by stimulated Raman scattering. The Thomson scattering signals measured in the experiment showed Langmuir waves with components both parallel and antiparallel to the incident laser's wave vector, k₀. The parallel component was attributed to stimulated Raman scattering. However, the Langmuir waves with components antiparallel to k₀, which cannot be explained by stimulated Raman scattering, were attributed to the Langmuir decay instability (LDI). The relative amplitude of the two Langmuir wave features and their angular width supported the conclusion that the Langmuir waves traveling antiparallel to the incident laser's wave vector were driven by the Langmuir decay instability.