Research output: Contribution to conference - Without ISBN/ISSN › Conference paper › peer-review
Research output: Contribution to conference - Without ISBN/ISSN › Conference paper › peer-review
}
TY - CONF
T1 - Components for the testing of a co-harmonic gyrotron cavity
AU - Constable, D. A.
AU - Ronald, Kevin
AU - He, Wenlong
AU - Fampris, Xenofon S.
AU - Phelps, Alan D. R.
AU - Cross, Adrian W.
PY - 2010/7/15
Y1 - 2010/7/15
N2 - A primary objective for the field of vacuum electronics is the development ofdevices capable of generating coherent, high power radiation within the sub-mmregime. The electron cyclotron maser instability offers an attractive method offulfilling such requirements, being a well established mechanism for obtainingcoherent, high power radiation within the mm-band. However, operation at highharmonics of the electron cyclotron frequency, ωc, proves challenging, given thesensitivity of parasitic modes to the large beam currents required.Previously, particle-in-cell simulations have been presented on thesimultaneous operation of a gyrotron cavity at the 2nd and 4th harmonics of theelectron 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 modeconversion experimentally. To that end, the design and fabrication of severaladditional components has been required. A brief overview of these components will be given, along with some initial experimental results
AB - A primary objective for the field of vacuum electronics is the development ofdevices capable of generating coherent, high power radiation within the sub-mmregime. The electron cyclotron maser instability offers an attractive method offulfilling such requirements, being a well established mechanism for obtainingcoherent, high power radiation within the mm-band. However, operation at highharmonics of the electron cyclotron frequency, ωc, proves challenging, given thesensitivity of parasitic modes to the large beam currents required.Previously, particle-in-cell simulations have been presented on thesimultaneous operation of a gyrotron cavity at the 2nd and 4th harmonics of theelectron 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 modeconversion experimentally. To that end, the design and fabrication of severaladditional components has been required. A brief overview of these components will be given, along with some initial experimental results
M3 - Conference paper
T2 - National Vacuum Electronics Conference (NVEC) 2010
Y2 - 14 July 2010 through 15 July 2010
ER -