Spontaneous Raman Scattering Measurements in the Exhaust Plume of a Micro-Thruster Nozzle Operated in a Low-Pressure Environment
Abstract
Measurements of spontaneous Raman scattering signals made within the exhaust plume of a micro-nozzle are reported and discussed. The measurements used a novel fiber-coupled, multiple-pass cell, spontaneous Raman scattering spectroscopy system, which was designed to measureH2 rotational Raman transitions within low-pressure environments void of optical access. When signal to noise ratios permit it, theoretical spectra can be fit to the results to yield temperature measurements. At low pressures, the number densities in the exhaust of a micro-nozzle operating in a high-vacuum environment are prohibitively low, rendering such measurements extraordinarily challenging. Methods to improve the quality of the measurements are discussed and contrasted in terms of the spatial resolution they offer. This work provides insights into the limitations of these non-intrusive measurements within the exhaust plume of a micro-nozzle and establishes a roadmap for improving their quality.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 17, 2020
- Accession Number
- AD1115449
Entities
People
- A. Skiba
- Alfredo D. Tuesta
- Brian T. Fisher
- Logan T. Williams
- Michael F. Osborn
Organizations
- United States Naval Research Laboratory