Abstract
In our gyro-TWT experiments, low-frequency oscillations (LFOs) had been observed. LFOs is a physical phenomenon usually caused by the electrons trapped between the magnetron injection guns (MIGs) and the interaction region. In this paper, the formation procedure and physical mechanism of LFOs are reported. Available methods including optimizing the magnetic field distribution in the beam compression region and loading bevel cuts on the second anode are involved to capture the trapped electrons, suppress the LFOs and improve the helical electron beam quality. Simulations and experimental results are in good agreement with each other and also reveal the reasonableness of this means. Finally, the influence of current capture ratio on LFOs and the beam quality are studied. With the current capture ratio increasing, the amplitude of LFOs decreases, the pitch factor maintains a constant about 1.2 and we also demonstrate a low transverse velocity spread about 3%.
Similar content being viewed by others
References
G. S. Nusinovich. Introduction to the Physics of Gyrotrons. Johns Hopkins University, Baltimore, 2004.
K. R. Chu, The electron cyclotron maser. Rev. Mod. Phys., vol. 76 (2004).
K. Sakamoto, A. Kasugai, K. Takahashi, R. Minami, N. Kobayashi, and K. Kajiwara. Achievement of robust high-efficiency 1 MW oscillation in the hard self-excitation region by a 170 GHz continuous-wave gyrotron. Nature Phys., vol. 3, no. 6, pp. 411–414, Jun. 2007
B. Piosczyk, G. Dammertz, O. Dumbrajs, M. V. Kartikeyan, M. K. Thumm, and X. Yang. 165-GHz coaxial cavity gyrotron. IEEE Trans. Plasma Sci., vol. 32, no. 3, pp. 853–860, Jun. 2004.
S.H. Kao, C. C. Chiu, K. F. Pao and K.R. Chu. Competition between harmonic cyclotron maser interaction in the Terahertz regime. PRL, 107, 135101 2011).
R. Yan, T. M. Antonsen and G. S. Nusinovich, Nonlinear analysis of low-frequency oscillations in gyrotrons. IEEE Trans. Plasma Sci. 38(6), 1178-1184 (2010).
S. E. Tsimring, Gyrotron electron beams: Velocity and energy spread and beam instabilities. Int. J. Infrared Millim. Waves, 22(10), 1433–1468 (2001).
R. Yan, T. M. Antonsen and G. S. Nusinovich. “Analytical theory of low frequency oscillations in gyrotrons.” Proc. of the IRMMW-THz Conference, Pasadena, CA, 2008, pp.1-2.
O. Louksha, B. Piosczyk, D. Samsonovl, G. Sominskil and M. Thumm. “Improvement of gyrotron beam quality by suppression of parasitic low-frequency oscillations”. Joint 31st International Conference on IRMMW-THz, China, Shanghai. 2006, pp.85.
A. J. Cerfon, E. Choi, C.D. Marchewka, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri and R. J. Temkin, Observation and study of low-frequency oscillations in a 1.5-MW 110-GHz gyrotron. IEEE Trans. Plasma Sci. 37(7), 1219-1224 (2009).
M. C. Lin and D.N. Smithe. “Study on low-frequency oscillations in a gyrotron using a 3D CFDTD PIC method”. IEEE IVEC, Bangalore, 2011, pp. 117-118.
O. I. Louksha, B. Piosczyk, G. G. Sominski, On potentials of gyrotron efficiency enhancement: measurements and simulations on a 4-mm gyrotron. IEEE Trans. Plasma Sci. 34(3), 502-512 (2006).
M. Y. Glyavin, A. L. Goldenberg, A. N. Kuftin, V. K. Lygin, A. S.Postnikova and V. E. Zapevalov, Experimental studies of gyrotron electron beam systems. IEEE Trans. Plasma Sci, 27(4), 474–483 (1999).
O. I. Louksha, G. G. Sominskii and D. V. Kasyanenko, Experimental study and numerical modeling of the electron beam formed in the electron-optical system of a gyrotron. J. Comm. Tech. Electron., 45,S71–S75(2000).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Pu, Y., Luo, Y., Yan, R. et al. Analysis of Low Frequency Oscillations in Magnetron Injection Guns. J Infrared Milli Terahz Waves 33, 141–148 (2012). https://doi.org/10.1007/s10762-011-9853-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10762-011-9853-y