@article {12773,
	title = {Broadband continuous frequency tuning in a terahertz gyrotron with tapered cavity},
	journal = {IEEE Transactions on Electron Devices},
	volume = {62},
	year = {2015},
	pages = {4278-4284},
	abstract = {Broadband continuous frequency tuning (CFT) in a terahertz gyrotron is promising for advanced terahertz applications. However, it is challenging to realize broadband CFT in a conventional open cavity, because a long cavity is helpful to expand the bandwidth but is generally difficult to suppress the high Q -factor gyromonotron competition. In this paper, a tapered cavity with a long effective interaction length is proposed to expand the CFT bandwidth. The tapered circuit can reduce the Q-factor of the first-order axial mode and accordingly suppress the gyromonotron competition. By selecting a reasonable Q-factor cavity, a gyrotron could generate effective radiation sequentially under gyromonotron and gyrobackward-wave oscillator (BWO) states during the magnetic field tuning. In gyromonotron range, the bandwidth is expanded because of the cutoff frequency shifting. On the other hand, in gyro-BWO range, the bandwidth is expanded because of the axial mode transition. The CFT bandwidth of 4 GHz is realized in a tapered 330-GHz TE12,4 mode low-voltage gyrotron. The principle is important for developing broadband CFT terahertz gyrotrons.},
	url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=7321019},
	author = {Xiang-Bo Qi and Chao-Hai Du and Pu-Kun Liu}
}
