Collective Thomson scattering (CTS) is crucial for inertial confinement fusion (ICF) hohlraum diagnostics, but measurement of the electron plasma wave (EPW) feature remains challenging. The conventional collisionless model suffers from two critical defects: under low-temperature, high-density conditions it predicts an extremely narrow EPW peak that causes numerical sampling distortion, and it predicts a monotonic increase of peak intensity with decreasing scattering angle, which would mislead experimental design. To overcome these issues, the Bhatnagar–Gross–Krook (BGK) collisional model is introduced. The BGK model predicts a nonmonotonic peak intensity with an optimal angle between 30° and 60°, and yields a finite, resolvable peak width that eliminates sampling artifacts. It also enables reliable assessment of drive-beam backgrounds. Guided by the predicted optimal angle, CTS experiments at 42° were performed on the Shenguang-100 kJ facility. For the first time, both ion and electron features were simultaneously measured in the hohlraum corona, with the electron signal clearly distinguishable from the background. Joint fitting provides the temporal evolution of electron density and temperature. This work establishes a unified, collision-corrected diagnostic framework that overcomes a long-standing obstacle to measuring electron density and temperature in ICF hohlraum plasmas.
Zhao et al. (Mon,) studied this question.