Hydrogen thermometry in aluminized propellant burns by hybrid fs/ps coherent anti-Stokes Raman scattering

摘要

A hybrid femtosecond/picosecond CARS instrument probed the Q-branch of molecular hydrogen in the multiphase plume of an aluminized solid propellant burn. A single 50 fs regenerative amplifier pumped an OPA and etalon, providing the Stokes and probe pulses respectively. The spectra were recorded at 1 kHz and fit to synthetic spectra to infer the gas rotational temperature. Recorded spectra required dynamic background corrections due to the intense emission of the propellant plume. Two different days of propellant burns were studied, with the lessons learned from nonresonant background issues with the first test applied to the second. For the second attempt, three burns were examined, with mean temperatures differing only by 30 K with a combined mean of 2574 K.