Application of the Bead Perturbation Technique to a Study of a Tunable 5 GHz Annular Cavity

Understand

Microwave cavities for a Sikivie-type axion search are subject to several constraints.

• In the fabrication and operation of such cavities, often used at frequencies where the resonator is highly overmoded, it is important to be able to reliably identify several properties of the cavity.
• Those include identifying the symmetry of the mode of interest, confirming its form factor, and determining the frequency ranges where mode crossings with intruder levels cause unacceptable admixture, thus leading to the loss of purity of the mode of interest.
• A simple and powerful diagnostic for mapping out the electric field of a cavity is the bead perturbation technique.