Periodic structures manufactured by 3D printing for electron beam excitation of high power microwave sources

A. R. Phipps, A. J. Maclachlan, L. Zhang, C. R. Robertson, I. V. Konoplev, K. Ronald, A. D. R. Phelps, A. W. Cross

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

2 Citations (Scopus)
17 Downloads (Pure)

Abstract

A Two-dimensional (2D) Periodic Surface Lattice (PSL) can produce distributed feedback in high power microwave sources driven by an oversized electron beam of annular geometry. Such 2D periodic structures can be formed in cylindrical waveguide with a grating machined on the walls, where the diameter of the waveguide is larger than the wavelength λ (D >> λ). In this case localised surface fields can be excited around the perturbations if the structure is radiated by an external source (for example an electron beam). Experiments were conducted using a velvet cathode electron gun with the electron accelerating voltage produced by a cable Blumlein generator. 'Additive Manufacturing' or '3D printing' was used to construct a silver 2D PSL quickly, efficiently and relatively inexpensively. The electron beam formed within an 18 mm bore 1.8 T solenoid was transported through the 7.2 mm inner diameter silver 2D PSL beam-wave interaction region. An 80 kV, 100 A electron beam with an outer diameter of 4 mm and inner diameter of 2mm which was approximately 1.8 mm away from the inner surface of the 2D PSL corrugation was measured. Millimetre wave radiation at a frequency of 80GHz at an output power of 130 ± 30 kW corresponding to an operating efficiency of 1.7 % was measured.

Original languageEnglish
Title of host publication2017 IEEE 21st International Conference on Pulsed Power
Place of PublicationPiscataway, NJ
PublisherIEEE
Number of pages4
ISBN (Print)9781509057481
DOIs
Publication statusPublished - 15 Feb 2018
Event21st IEEE International Conference on Pulsed Power - the Hilton Metropole Hotel, Brighton, United Kingdom
Duration: 18 Jun 201722 Jun 2017
Conference number: 21

Conference

Conference21st IEEE International Conference on Pulsed Power
Abbreviated titlePPC 2017
Country/TerritoryUnited Kingdom
CityBrighton
Period18/06/1722/06/17

Funding

3D printing developed in the mid 1980’s [10] and the number of its applications is continuing to expand. The tolerances achievable with 3D printing are projected to improve over time as the technology develops, resulting in higher degrees of accuracy [11]. 3D printing is used in the initial creative process that results in structures such as the example shown in Figure 1. It involves an additive process by which consecutive layers in the x-z plane are deposited sequentially in the +ve y direction. The printing process follows the pattern in a given CAD input file, usually in the STL (Stereolithograph) file format where every face is built from a series of interconnected triangles represented by 3 separate 32-bit floating-point Cartesian coordinates. The physical parameters of the W- ? Work supported in part by the EPSRC who sponsored the research studentships of A.R. Phipps and A.J. MacLachlan. The authors acknowledge the support of the Leverhulme Trust Network “Advanced Research on Generation of THz and X-ray Radiation” (IN-2015-012). This material is based upon work supported by the Air Force Office of Scientific Research under award numbers FA8555-13-1-2132 and FA9550-17-1-0095.

Keywords

  • Periodic Surface Lattice (PSL)
  • distributed feedback
  • 3D printing
  • electron beam

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