Hybrid photonic-bandgap accelerating cavities

TL;DR

This paper explores hybrid photonic-bandgap cavities with dielectric and metallic components, aiming to develop high-quality accelerating resonators, and demonstrates their potential through simulations and experimental validation at microwave frequencies.

Contribution

It introduces hybrid dielectric-metal photonic bandgap structures with various configurations, showing potential for high-Q resonators for particle acceleration applications.

Findings

Hybrid structures can achieve higher quality factors than purely dielectric ones.

Superconducting plates further enhance electromagnetic confinement and Q factors.

Experimental results validate the simulation predictions at microwave frequencies.

Abstract

In a recent investigation, we studied two-dimensional point-defected photonic bandgap cavities composed of dielectric rods arranged according to various representative periodic and aperiodic lattices, with special emphasis on possible applications to particle acceleration (along the longitudinal axis). In this paper, we present a new study aimed at highlighting the possible advantages of using hybrid structures based on the above dielectric configurations, but featuring metallic rods in the outermost regions, for the design of extremely-high quality factor, bandgap-based, accelerating resonators. In this framework, we consider diverse configurations, with different (periodic and aperiodic) lattice geometries, sizes, and dielectric/metal fractions. Moreover, we also explore possible improvements attainable via the use of superconducting plates to confine the electromagnetic field in the longitudinal direction. Results from our comparative studies, based on numerical full-wave simulations backed by experimental validations (at room and cryogenic temperatures) in the microwave region, identify the candidate parametric configurations capable of yielding the highest quality factor.