AC Plasma Sensor For High Enthalpy Hypersonic Test Facilities

Spectral Energies and the University of Notre Dame is developing a new class of point-wise sensors for high-enthalpy conditions that rely on the use of a weakly ionized AC discharge between two electrodes as the main sensing element. The advantages of this approach include a native high bandwidth with a theoretical maximum in excess of 15 MHz and a simple mechanical design that is inherently robust to mechanical and thermal stress. The sensor volume can be as small as a 1 mm3. Variations of this sensor have reached TRL-5 through demonstrations in full-scale gas-turbines, hypersonic facilities, high pressures and temperature facilities. These tests include a measurement in the augmentor of a General Electric J85-5H afterburning turbojet at the University of Tennessee Space Institute (UTSI), a rotating detonation engine at the University of Cincinnati, and hypersonic conditions at the Wright Patterson AFB. Calibrations for velocity have been published in journal article, while sensitivity to pressure has also been demonstrated. Additional flow parameters including temperature and gas species have been demonstrated through the analysis of the optical emission of the discharge which provides spectral content of the gas under test. These capabilities will be further refined for the requested conditions.