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Description
We demonstrate a broadband frequency tuning mechanism applied to a superconducting Nb₃Sn-coated microwave cavity for wave-like dark matter (DM) searches. The cavity consists of two halves: one fixed and one mounted on a sliding cart, enabling a controllable axial gap of up to 6 mm. This "tuning-by-opening" approach changes the effective radius of the cavity and shifts the resonance from 9 GHz down to 7.8 GHz, a much broader range than typical systems. Finite-element simulations indicate that radiative losses remain negligible, with intrinsic quality factors on the order of 10⁷ preserved for apertures up to several millimeters. Experimental measurements using both discrete spacers and the continuous translation confirm Q₀ values exceeding the DM quality factor of 10⁶ across the full tuning range. The combination of high Q and wide, continuous tuning makes this technique a promising tool for next-generation haloscope searches, including implementations compatible with high magnetic fields required for axion searches.