Computational study of a novel microwave excited plasma sensor for aerodynamic flows

Abstract

We present a computational study that demonstrates the concept of a microwave excited plasma flow sensor. The geometric configuration consists of an array of circularly arranged “receiver” (ground) electrodes that surround a central “transmitter” (excited) electrode that is flush mounted on a surface exposed to incident flow. Microwave excitation is used to strike a low-temperature plasma between the transmitter electrode and the receiver electrode. Depending on the flow direction, a more intense plasma kernel is formed between the transmitter electrode and the downstream electrode for sufficiently strong excitation conditions. The differential current between the receiver electrodes is used to establish the flow direction and magnitude. The computational model establishes the effectiveness of the concept as a flow sensor. Parametric studies involving excitation voltages, flow velocities, scale lengths, electrode shape, and excitation frequency are performed. It is observed that the sensitivity of the device to the imposed flow is considerably improved with increasing excitation frequency in the microwave regime.