Excitation of extraordinarily polarized azimuthal eigen modes by modulated annular electron beam is shown to be characterized by the increase of instability growth rates compared with the case of non-modulated electron beam. Interaction between the modulated beam and azimuthal eigen modes happens in the range of electron cyclotron frequency in waveguides with metal walls, which are partially filled with cold magneto-active plasma. Non-linear set of differential equations, which describs excitation of these azimuthal modes by an annular electron beam is derived and analyzed numerically. Different scenarios of the beam-plasma interaction depending on relation between azimuthal mode number of the exited waves and periodicity of azimuthal modulation of the beam density, degree and manner of the beams' modulation are studied numerically.
2. Humphries, S., Charged Particle Beams, John Wiley and Sons Inc., New York , 1990.
3. Vlasov, A. N., A. G. Shkvarunets, and J. Rodgers, "Overmoded GW-class surface waves microwave oscillators," Special Issue of IEEE-PS on High-power Microwave Generators, Vol. 28, 550-560, 2000.
4. Barker, R. J. and E. Schamiloglu, High-power Microwave Sources and Technologies, New-York, 2001.
5. Ederra, I., J. C. Iriarte, R. Gonzalo, and P. de Maagt, "Surface waves of finite size electromagnetic band gap woodpile structures," Progress In Electromagnetics Research B, Vol. 28, 19-34, 2011.
6. Girka, V. O., I. O. Girka, A. V. Girka, and I. V. Pavlenko, "Theory of azimuthal surface waves propagating in non-uniform waveguides," Journal of Plasma Physics, Vol. 77, Part 4, 493-519, 2010.
7. Girka, I. O., V. O. Girka, and I. V. Pavlenko, "Excitation of ion azimuthal surface modes in a magnetized plasma by annular flows of light ions," Progress In Electromagnetics Research M, Vol. 21, 267-278, 2011.
8. Fujiwara, M., et al., "Experiments on NBI plasmas in LHD," Plasma Phys. Control. Fusion, Vol. 41, No. 12B, 157-166, 1999.
9. Sircombe, N. J., et al., "Plasma heating by intense electron beams in fast ignition," Plasma Phys. Control. Fusion, Vol. 50, No. 6, 065005, 2008.
10. Wu, J., C. Xiong, and S. Liu, "Excitation of microwave by an annular electron beam in a plasma-filled dielectric lined waveguide," International Journal of Infrared and Millimeter Waves, Vol. 16, No. 9, 1573-1581, 1995.
11. Legenkiy, M. N. and A. Y. Butrym, "Pulse signals in open circular dielectric waveguide," Progress In Electromagnetics Research Letters, Vol. 22, 9-17, 2011.
12. Norreys, P. A., et al., "Observation of annular electron beam transport in multi-TeraWatt laser-solid interactions," Plasma Phys. Control. Fusion, Vol. 48, No. 2, L11-L22, 2006.
13. Lau, Y. Y., "Radiation generated by rotating electron beams," Proceed. Symp. Non-Neutral Plasma Physics, 210-223, Washington, USA, 1988.
14. Kainer, S., et al., "Nonlinear wave interactions and evolutions of a ring-beam distribution of energetic electrons," Phys. Fluids, Vol. 31, No. 8, 2283-2284, 1988.
15. Kho, T. H., A. T. Lin, and L. Chen, "Gyrophase-coherent electron cyclotron maser," Phys. Fluids, Vol. 31, No. 10, 3120-3126, 1988.
16. Kapitanov, A. N., et al., "Solution of a set of Maxwell-Lorentz equations for a ring relativistic electron beam," Plasma Physics Reports, Vol. 35, No. 6, 510-517, 2009.
17. Girka, V. O., I. O. Girka, and I. V. Pavlenko, "Excitation of azimuthal surface modes by relativistic flows of electrons in high-frequency range," Plasma Physics Reports, Vol. 37, No. 5, 447-454, 2011.
18. Girka, V. O. and S. Yu. Puzyrkov, "Nonlinear interaction of an annular electron beam with azimuthal surface waves," Plasma Physics Reports, Vol. 28, No. 4, 351-358, 2002.
19. Kirichenko, Y. V., "Generation and amplification of electromagnetic waves by an annular electron beam in a radial electric field in free space," Technical Physics, Vol. 45, No. 8, 1096-1097, 2000.
20. Malek, M. F. B. A., J. Lucas, and Y. Huang, "The engineering and construction of a pre-bunched free electron maser," Progress In Electromagnetics Research, Vol. 95, 19-38, 2009.
21. Anisimov, I. O., M. J. Soloviova, "The evolution of a modulated electron beam in a dense plasma barrier," Plasma Phys. Control. Fusion, Vol. 53, No. 7, 074007, 2011.
22. Korenev, B. G., Bessel Functions and Their Applications, Chapmen & Hall/CRC Press LLC, Bora Raton, Florida , 2002.
23. Krall, N. A. and A. W. Trivelpiece, Principles of Plasma Physics, McGraw-Hill, New York, 1973.