Tunable axion plasma haloscopes

Understand

We propose a new strategy to search for dark matter axions using tunable cryogenic plasmas.

• Unlike current experiments, which repair the mismatch between axion and photon masses by breaking translational invariance (cavity and dielectric haloscopes), a plasma haloscope enables resonant conversion by matching the axion mass to a plasma frequency.
• A key advantage is that the plasma frequency is unrelated to the physical size of the device, allowing large conversion volumes.
• We identify wire metamaterials as a promising candidate plasma, wherein the plasma frequency can be tuned by varying the interwire spacing.