Spatially resolved excitation temperature measurements in a hypersonic flow using the hook method.

Area of Science:

• Atomic spectroscopy
• Fluid dynamics
• Physical chemistry

Background:

• The hook method is a powerful spectroscopic technique for determining atomic species concentrations.
• Previous methods lacked spatial resolution, limiting analysis to uniform conditions.
• Addressing this gap requires extending the hook method to map variations within a test plane.

Purpose of the Study:

• To experimentally demonstrate the spatial resolution capabilities of an extended hook method.
• To apply this enhanced technique to analyze nonuniformities in both flame and hypersonic flow environments.
• To investigate the distribution of ground state sodium and chromium impurities in dynamic gas flows.

Main Methods:

• Experimental application of the extended hook method to measure integrated line density variations of sodium in a flame.
• Simultaneous measurement of hook separations for Cr I lines in a hypersonic CO(2) flow over a cylinder.
• Spatially resolving variations along the spectrometer slit in a shock tunnel.

Main Results:

• Successfully demonstrated spatial resolution of integrated line density for ground state sodium in a flame.
• Measured spatial variations in chromium impurity line separations within a hypersonic CO(2) flow.
• Obtained population distributions enabling temperature comparisons.

Conclusions:

• The extended hook method effectively provides spatial resolution of atomic species and their properties.
• This technique is applicable to diverse environments, including flames and hypersonic flows.
• The results allow for detailed analysis of gas properties and impurity distributions in complex flows.