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THPD51 |
W-Band Cherenkov Maser Based on a Periodic Surface Field Structure | |
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Funding: Work supported by EPSRC Two-dimensional Bragg structures have been useful in producing distributed feedback in an FEM driven by an oversized annular electron beam [1]. The Bragg structures in this case act as frequency selective mirrors allowing the production of narrow band microwaves [2]. This structure can be observed using a hollow, copper, cylindrical waveguide with a sinusoidal grating machined into the walls where the diameter of the waveguide is much larger than λ. Localised surface fields are excited around the perturbations if the structure is radiated by an external electron beam [3]. The resultant eigenfield can be described as a superposition of a near cut-off volume field which synchronises the localised surface partial fields. A relativistic electron beam travelling close to the structure interacts with the spatial harmonics of the surface field propagating with υp< c. In this paper we demonstrate a novel high Q cavity operating at W band (75-110GHz), where there is coupling between a near cut-off TM0,6 volume field and an evanescent HE1,20 surface field, produced within the structure. Results of the numerical modelling of this device using the PIC code MAGIC will be presented. 1. N.S. Ginzburg, N. Peskov, et al, J Appl Phys, 92, pp. 1619-1629, 2002 2. I.V. Konoplev, et al, Appl Phys Lett, 92, 211501 2008 3. I.V. Konoplev, A. Maclachlan. et al, Phys Rev A, 84, 013826 2011 |
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