High-Bandwidth High-Resolution Sensor for Hypersonic Flows

A working prototype of a miniature 2 MHz a.c. driven, weakly-ionized plasma anemometer for measurements at hypersonic Mach numbers was developed during a Phase I effort. This device uses a plasma discharge between two encapsulated electrodes as the primary sensing element. The discharge has a demonstrated sensitivity to mean and dynamic mass-flux variations up to Mach number = 1.4 and 200 kHz respectively. In principle, a frequency response up to the 2 MHz carrier frequency is possible. The probe has also been tested for repeatability and has shown no hysteresis in its dependence to mass-flux. This sensor has applications for measurements in gas-turbine machinery, shock tubes, shock-boundary layer experiments, high-enthalpy hypersonic flows, and in plasma tunnels. The proposed Phase II effort is based on the success of the Phase I research and is designed to further advance and expand the capabilities of the plasma sensor to the point where it becomes a viable laboratory and industrial flow diagnostic tool. To achieve this we propose to: 1. Develop a working prototype with “turn-key” electronics suitable for research laboratory use. 2. Develop surface-mount plasma sensors for velocity, shear stress and acoustic measurements. 3. Develop wireless transmission of the sensor output. 4. Develop an integrate plasma sensor and actuator package. 5. Explore micro-packaging technology for plasma sensors for use in distributed sensing arrays.