RF-components embedded with photonic-band-bap (PBG) and fishnet-metamaterial structures for high frequency accelerator application

TL;DR

This paper presents innovative RF components embedded with photonic band gap and fishnet-metamaterial structures, demonstrating improved mode suppression and enhanced Q-factor for high-frequency accelerator applications.

Contribution

It introduces novel RF waveguide and cavity designs with PBG and fishnet structures, showing significant mode suppression and Q-factor improvements through simulation analysis.

Findings

Effective suppression of non-PBG modes (~ -14.3 dB/cm)

Propagation loss of PBG modes (~2 dB)

Improved Q-factor and field gradient in fishnet-embedded cavities

Abstract

In the development of high efficiency and high gradient RF-accelerators, RF waveguides and cavities have been designed with Photonic Band Gap (PBG) and fishnet- metamaterial structures. The designed structures are comprised of a periodically corrugated channel sandwiched between two photonic crystal slabs with alternating high to low dielectric constants and a multi-cell cavity-resonator designed with fishnet-metamaterial apertures. The structural designs of our interest are intended to only allow an operating-mode or -band within a narrow frequency range to propagate. The simulation analysis shows that trapped non-PBG modes are effectively suppressed down to ~ -14.3 dB/cm, while PBG modes propagated with ~2 dB of insertion loss, corresponding to ~1.14 dB/cm attenuation. The pre- liminary modeling analysis on the fishnet-embedded cavity shows noticeable improvement of Q-factor and field gradient of the operating mode (TM010) compared to those of typical pillbox- or PBG-cavities. Fabrication of the Ka-band PBG-waveguide and S-band fishnet cavity structures is currently underway and they will be tested with a microwave test bench/8510C Network Analyzer and 5.5 MW S-band klystron. These structures can be applied to stable short-bunch formation and mono chromatic radiation in high frequency accelerators.