Topological Surface Waves on Low-Temperature Gaseous Magnetized Plasma: Theory, Computation, and Detection

In low-temperature gaseous magnetized plasma, it has recently been recognized that the non-trivial topology of bulk electromagnetic wave dispersion bands, induced by the breaking of time-reversal symmetry from the applied magnetic field, predicts robust unidirectional surface waves localized to the plasma boundary. In this thesis, we present the first two experiments to explicitly detect and measure these topological surface waves. The first experiment utilizes two small dipole antennas to excite and measure the frequency of a topological surface wave which arises from the upper Weyl point, k+, in the bulk dispersion bands of magnetized plasma. The second experiment utilizes a corrugated metasurface waveguide to excite and measure both frequency and wavevector of a topological surface wave from the lower Weyl point, k-. Both experiments are done with plasma generated in a mercury-argon gas-discharge tube, and they lay the groundwork for future extensive mapping of topological surface wave dispersion using the developed methods. Additionally, we overview the theory of topological surface waves and develop a simpler theoretical basis for correctly computing the topology of bulk magnetized plasma, which requires special treatment since plasma is a continuous medium without a compact Brillouin zone. We also develop a framework to numerically solve for plasma surface wave dispersion, which illustrates the predictions from band topology and supports the experimental results.