Investigation of Superradiant Overmoded Two-Dimensional Periodic Surface Cavities for High Power Microwaves
Abstract
In achieving the key objectives of this proposal we will demonstrate the phase locking of two superradiant, over moded 100GHz sources by combining several contemporary research advances leading to the development of novel microwave sources with world leading power capabilities. When used as the interaction region of a milimeter wave source, complex electrodynamic structures with two-dimensional sinusoidal corrugations can provide mode rarefication by enabling coupling of high-order volume and surface waves to form a cavity eigenmode. Preliminary studies have established the potential for powerful vacuum electronic sources based on cylindrical, two-dimensional periodic surface lattice (2D-PSL) structures with diameters many times the operating wavelength. We foresee the opportunity to explore and develop superradiant 2D-PSL sources by capitalizing on this uniqueability to control and manipulate electromagnetic fields. Superradiance can be instigated by launching an extended electron bunch through an optimally designed 2D-PSL structure. The resultant superradiant pulses are short in duration and extremely high in instantaneous power. Obtaining, and maintaining, a high quality annular electron beam, narrow in radial extent and driven close to the inner cavity wall, is essential for superradiant emission. In the present proposal we plan to simulate the dynamics of electrons launched through the 2D-PSL structure from a thin annular emitter comprised of a ring of carbon nanotubes (CNTs) imbedded in a cathode assembly. Individual superradiant2D-PSL sources with CNT cathodes have the potential to deliver substantial pulsed energy while world record power levels can be realized through the phase synchronous operation of N such sources via constructive interference. Combining the N individual electric fields enables one to achieve effective peak output power flux densities of N2.ThisN2upscaleis provided partly by the additional sources, and also by the narrowing of the radiation pattern, producing a focused, intense beam. In this proposal, we intend to demonstrate this proof-of-concept for a pair of 100GHzsuperradiant sources with CNT cathodes andoversized2D-PSLinteraction cavities with diameter to wavelength ratios, D/?~6to show a fourfold increase in peak output power flux density, or Equivalent Radiated Power (EPR).The performance of (i) an individual superradiant 2D-PSL source and (ii) a pair of phase synchronous superradiant 2D-PSL sources will be simulated to predict the potential output powers and prove the fundamental principle. We predict GigaWatt power levels which can be further enhanced; primarily by increasing the number of sources in the array, but also by increasing D/? of the individual PSL sources. Historically, phase-locking has been demonstrated only for lower power, one-dimensional sources and accomplishing our goal will be a “world-first”. Our proposed complex2D-PSL interaction regions are highly adaptable and scalable for different operating frequencies whilst the dispersive properties can be modified to support different regimes of operation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 20, 2023
- Source ID
- FA86552217251
Entities
People
- Adrian Cross
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Strathclyde