@article {12779,
	title = {Modal transition and reduction in a lossy dielectric-coated waveguide for gyrotron-traveling-wave tube amplifier applications},
	journal = { IEEE Transactions on Electron Devices},
	volume = {56},
	year = {2009},
	pages = {839-845},
	abstract = {A metal cylindrical waveguide coated with an inside layer of lossy dielectric which affects the propagation characteristics of a guided electromagnetic mode is investigated for gyrotron-traveling-wave tube (gyro-TWT) amplifier applications. This paper reveals a series of novel phenomena. The dispersion curve of a higher order mode has a turning point during its evolvement from the fast wave region to the slow wave region. An electromagnetic mode in the lossy dielectric-coated waveguide exhibits a transverse partial-standing-wave distribution. The dielectric loss induces modal transition which results in the dispersion curves of a pair of nearby modes crossing each other and interchanging mode structures. Modal reduction caused by strong dielectric loss merges a pair of nearby modes into one. In this one merged mode, the dielectric-coated waveguide is equivalent to a conventional cylindrical waveguide with imperfect conducting wall. This improved understanding of lossy dielectric-coated metal cylindrical waveguide is of value and usefulness for application toward gyro-TWTs capable of high-power and wide bandwidth.},
	url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4804615},
	author = {Chao-Hai Du and Qian-Zhong Xue and Pu-Kun Liu and Ming-Hong Wang}
}
