Quantitative one-dimensional imaging using picosecond dual-broadband pure-rotational coherent anti-Stokes Raman...

Area of Science:

• * Spectroscopic diagnostics
• * Laser-based measurement techniques
• * Combustion and plasma science

Background:

• * Accurate in-situ measurements of temperature and species concentrations are crucial for understanding combustion processes.
• * Traditional methods like thermocouples have limitations in spatial resolution and temporal response.
• * Coherent anti-Stokes Raman spectroscopy (CARS) offers non-intrusive measurement capabilities.

Purpose of the Study:

• * To demonstrate and validate a picosecond dual-broadband pure-rotational CARS (RCARS) technique for 1D imaging.
• * To measure temperature and O(2):N(2) concentration ratios along a 1D line.
• * To assess the accuracy and precision of the developed 1D imaging RCARS method.

Main Methods:

• * Employed picosecond dual-broadband pure-rotational CARS in a 1D imaging configuration.
• * Acquired up to 330 spatially resolved RCARS spectra along a 1D line (up to 12 mm).
• * Conducted measurements in heated N(2) flow (410 K-1200 K) and demonstrated flame temperature measurements (2100 K).

Main Results:

• * Achieved single-laser-pulse imaging at temperatures up to ~1200 K.
• * Demonstrated shot-averaged imaging at flame temperatures (~2100 K).
• * Obtained temperature measurements with deviations <30 K compared to thermocouple readings up to 1205 K.

Conclusions:

• * Picosecond 1D imaging RCARS provides accurate and precise temperature and concentration measurements.
• * The technique is suitable for single-shot measurements at high temperatures.
• * Offers a valuable tool for combustion diagnostics, complementing existing methods.