  Nonreciprocal transport of electromagnetic waves within magnetized plasma is
a powerful building block towards understanding and exploiting the properties
of more general topological systems. Much recent attention has been paid to the
theoretical issues of wave interaction within such a medium, but there is a
lack of experimental verification that such systems can be viable in a lab or
industrial setting. This work provides an experimental proof-of-concept by
demonstrating nonreciprocity in a unit component, a microwave plasma
circulator. We design an E-plane Y junction plasma circulator operating in the
range of 4 to 6 GHz using standardized waveguide specifications. From both
simulations and experiments, we observe wide band isolation for the power
transmission through the circulator. The performance and the frequency band of
the circulator can be easily tuned by changing the plasma density and the
magnetic field strength. By linking simulations and experimental results, we
estimate the plasma density for the device.

Plasma Physics;Signal Processing