On the possibility of design of klystrons with 3D grouping of electron beam

 

D. A. Mikheev, V. L. Savvin, R. V. Egorov, K. T. C. Wu

M.V. Lomonosov Moscow State University, Faculty of Physics, Leninskie Gory, Moscow, 119991

 

 The paper is received on March 26, 2018

 

Abstract. A new principle of electron beam grouping is proposed, which can be formulated as follows. Electrons with cyclotron rotation, having equal initial longitudinal velocities and entering inhomogeneous magnetic field, having different initial input coordinates, move as a result along different trajectories, experiencing different effect of the inhomogeneous magnetic field and, therefore, different change of longitudinal velocity. As a result of periodic changes of electron’s input conditions, the continuous electron beam turns into a sequence of periodic electron concentrations. The principal difference of the considered 3D grouping of the electron beam from usual electron bunching during one-dimensional motion is that electron concentrations may not be accompanied by an increase of the spatial charge density. Due to the fact that the electron trajectories are three-dimensional and do not coincide with the axis of the grouping region, electron concentrations will be distributed over the cross-sectional area of the drift tube. As a result, the spatial charge forces may generate significantly weaker influence on the grouping process.

The dynamic behavior of beam current harmonics at the process of 3D grouping is studied. It is shown that the amplitude of the first beam current harmonic can reach values close to the maximum amplitude at the “classical” grouping. The efficiency of the three-resonator klystron with a 3D grouping of electron beam was evaluated with an output power 2.5 kW. The calculated gain reached 40 dB, which is close to the value of the gain of the similar "classic" klystron.

Key words: electron beam, grouping, space charge, klystron.

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For citation:
D. A. Mikheev, V. L. Savvin, R. V. Egorov, K. T. C. Wu. On the possibility of design of klystrons with 3D grouping of electron beam. Zhurnal Radioelektroniki - Journal of Radio Electronics. 2018. No. 4. Available at http://jre.cplire.ru/jre/apr18/1/text.pdf

DOI  10.30898/1684-1719.2018.4.1