Electron Beam Visualization in Hypersonic Airflows

The electron beam fluorescence technique has been employed for visualizing hypersonic airflow fields. A high current electron beam generator was used to provide electron beams with currents up to 50 ma at voltages up to 20 kv. Applications of the technique at low densities illustrate that many details of the flowfield can be obtained in density regions where conventional optical systems fail to yield useful results. Techniques for obtaining quantitative density measurements with photographic techniques are discussed. The value and versatility of the method is demonstrated by results obtained with a sharp cone model and an advanced ramjet aircraft configuration in a Mach 10 airflow field.