Electron Density Measurement of Surface Dielectric Barrier Discharges Using Photonic Crystals

This project, which is a collaboration between groups at Stanford and at CNRS (France) investigates the use of one-dimensional plasma photonic crystals (which are periodic arrays of ionized gases that have a tunable refractive index in the microwave range of the electromagnetic spectrum) for the measurement of the electron density – the principal constituent of the ionized gas that affects the refractive index. The incident EM waves scatters off of the periodic structure much like x-rays scatter off of crystals. We exploit this interaction to make accurate measurements of the ionized gas properties. This understanding will also contribute to the use of these photonic crystal devices to control and manipulate EM waves in ways that are previously unattainable by other means. The periodic array produces a region of the spectrum that forbids EM wave propagation (a “bandgap”), very similar to that which is seen in some atomic crystals. This bandgap can be tuned in its frequency by varying the electron density in a controlled way. Our project will explore methods of establishing this control.