@article {12778,
	title = {Development of a magnetic cusp gun for terahertz harmonic gyrodevices},
	journal = {IEEE Transactions on Electron Devices},
	volume = {59},
	year = {2012},
	pages = {3635-3640},
	abstract = {A magnetic cusp gun (MCG) is being developed to generate an axis-encircling electron beam, which is called the large orbit beam, which is going to drive a 0.396-THz fourth-harmonic gyrotron. Developing an MCG imposes crucial challenges on a simultaneously minimizing guiding center deviation and velocity spread of the electron beam, particularly because an ultrahigh magnetic compression ratio is unavoidable, as is the case for a terahertz (THz) gyrotron. The study of the electron dynamics in the MCG reveals that, close to the emitter, a pair of focusing electrodes are employed to construct a special focusing and accelerating electric field as a way to balance the space-charge influence and guiding center deviation. Investigation indicates that both the electron-beam generalized-angular-momentum spread and the guiding center distribution are the critical factors contributing to beam parameter spread. Intensive optimization generates a high-power MCG with a pitch factor of 1.5, the highest magnetic field of 4 T, minimum transverse velocity spread of 1.1\%, and a beam current of 2 A. The key parameters exhibit excellent stability tuning over a wide range of beam current and magnetic field. These merits enable the harmonic gyrotrons or even the frequency-tunable THz gyrotrons to be developed.},
	url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6352876},
	author = {Chao-Hai Du and T. H. Chang* and P. K. Liu* and C. P. Yuan and S. J. Yu and G. F. Liu and Vladimir L. Bratman and Mikhail Yu. Glyavin and Yu. K. Kalynov}
}
