Components for the testing of a co-harmonic gyrotron cavity

Constable, D. A. and Ronald, Kevin and He, Wenlong and Fampris, Xenofon S. and Phelps, Alan D. R. and Cross, Adrian W. (2010) Components for the testing of a co-harmonic gyrotron cavity. In: National Vacuum Electronics Conference (NVEC) 2010, 2010-07-142010-07-15, Cockcroft Institute.

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A primary objective for the field of vacuum electronics is the development of devices capable of generating coherent, high power radiation within the sub-mm regime. The electron cyclotron maser instability offers an attractive method of fulfilling such requirements, being a well established mechanism for obtaining coherent, high power radiation within the mm-band. However, operation at high harmonics of the electron cyclotron frequency, ωc, proves challenging, given the sensitivity of parasitic modes to the large beam currents required. Previously, particle-in-cell simulations have been presented on the simultaneous operation of a gyrotron cavity at the 2nd and 4th harmonics of the electron cyclotron frequency[1]. Such a co-harmonic scheme is used to obtain high frequency radiation through the direct excitation of a low harmonic signal. By then trapping the low harmonic within the interaction region, through the use of a cut-off aperture, pure output of the high harmonic signal can be realised. However, the intended output radiation is dominated by a mode converted 2nd harmonic signal. Analysis of the setup suggests that such mode conversion occurs due to the cut-off aperture, and while the magnitude of the converted signal can be reduced, it cannot be eliminated entirely. As a result, the current focus is to confirm the presence of this mode conversion experimentally. To that end, the design and fabrication of several additional components has been required. A brief overview of these components will be given, along with some initial experimental results

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Contribution to Conference (Paper)
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National Vacuum Electronics Conference (NVEC) 2010
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29 Jul 2016 08:20
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22 Nov 2022 14:18