Single-shot picosecond pump coherent Rayleigh scattering thermometry.

Area of Science:

• Physics
• Spectroscopy
• Fluid Dynamics

Background:

• Coherent Rayleigh scattering (CRS) experiments traditionally face challenges with shot-to-shot variations due to unseeded nanosecond pump pulses.
• Developing faster, more repeatable diagnostic techniques is crucial for analyzing complex and dynamic environments.

Purpose of the Study:

• To present a single-shot coherent Rayleigh scattering (CRS) technique with measurement times under 10 nanoseconds.
• To improve the repeatability and accuracy of CRS measurements compared to previous methods.

Main Methods:

• Utilized a mode-locked picosecond pump laser for repeatable electrostrictive forcing.
• Employed a virtually imaged phased array to disperse the CRS signal onto an EMCCD sensor.
• Applied a least-squares fitting routine to compare experimental spectra with an existing kinetic model.

Main Results:

• Achieved measurement times less than 10 nanoseconds.
• Demonstrated quantitative measurements at ambient and low-pressure (2 Torr), low-temperature (100 K) conditions.
• Reported single-shot statistics with precision and accuracy within 4% at ambient conditions and 8% at low density/temperature.

Conclusions:

• The developed single-shot CRS technique provides rapid and repeatable measurements.
• This diagnostic tool shows significant potential for multi-parameter measurements in challenging environments like high-speed aerodynamic facilities.