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Free-electron masers based on two-dimensional distributed feedback

Phelps, A.D.R. and Konoplev, I.V. and Cross, A.W. and Macinnes, Philip and He, W. and Ronald, K. and Whyte, C.G. and Robertson, C.W. and , IEEE (2007) Free-electron masers based on two-dimensional distributed feedback. In: Proceedings of the Eighth IEEE International Vacuum Electronics Conference. International Vacuum Electronics Conference IVEC . IEEE, pp. 423-424. ISBN 1-4244-0633-1

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Abstract

The results of experimental studies of a coaxial free-electron masers (FEM) based on two-dimensional distributed feedback are presented. In the first set of experiments the FEM's interaction region was formed by a two-mirror cavity with 2D Bragg structures as input and output mirrors. In the second set of experiments a cavity with 2D and 1D mirrors was used. In both cases the input mirror provided two-dimensional (2D) distributed feedback and ensured mode selection over the wave azimuthal index, while the output mirror was used to close the feedback loop inside the two-mirror cavity. It was demonstrated that substituting the 2D output mirror with a 1D Bragg structure increased the output power while still maintaining spectral purity and spatial and temporal coherence. The FEM has been driven by an oversized high-current (1.5 kA) thin annular electron beam of 200 ns pulse duration. An maximum output power of ~60 MW corresponding to an efficiency of 10% was measured for an FEM based on 2D/1D cavity. The directional mode pattern of the microwave radiation from the output horn was also measured and compared with theoretical prediction. Analysing the spectrum of the RF signal the location of the operating frequency was found.

Item type: Book Section
ID code: 18155
Notes: Also preseant at http://strathprints.strath.ac.uk/18126/
Keywords: Bragg gratings, electron beams, feedback, masers, mirrors, annular electron beam, coaxial free-electron masers, microwave radiation pattern, spatial coherence, spectral purity, Physics
Subjects: Science > Physics
Department: Strathclyde Business School > Strategy and Organisation
Faculty of Science > Physics
Related URLs:
    Depositing user: Strathprints Administrator
    Date Deposited: 11 May 2010 14:34
    Last modified: 04 Oct 2012 16:21
    URI: http://strathprints.strath.ac.uk/id/eprint/18155

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