A plasma haloscope has recently been proposed as a feasible approach to
extend the search for dark matter axions above 10 GHz (∼ 40 μeV),
whereby the microwave cavity in a conventional axion haloscope is supplanted by
a wire array metamaterial. As the plasma frequency of a metamaterial is
determined by its unit cell, and is thus a bulk property, a metamaterial
resonator of any frequency can be made arbitrarily large, in contrast to a
microwave cavity which incurs a steep penalty in volume with increasing
frequency. We have investigated the basic properties of wire array
metamaterials through S21​ measurements in the 10 GHz range. Excellent
agreement with theoretical models is found, by which we project achievable
quality factors to be of order 104 in an actual axion search. Furthermore,
schemes for tuning the array over a usable dynamic range (30% in frequency)
appear practical from an engineering perspective.Comment: to be submitted to Physical Review Letters; typos correcte