Thomson scattering was used to measure the spectrum of Langmuir waves, in both frequency and wave number, driven below quarter-critical density by a laser beam. These measurements were capable of detecting and identifying waves driven by stimulated Raman scattering(SRS) and also of detecting waves driven by other effects such as the bump-on-tail instability postulated by the enhanced Thomson scattering model of Raman emission. The observed Langmuir waves were consistent with SRS and not with other possible sources. The width in k-space of the measured Thomson scattering signals also has implications for the saturation amplitude of the Langmuir waves.
Physics of Plasmas6, no. 11 (21 July 1999): 4284–.