Contribution to the theory of longitudinal instability of an electron beam in a waveguide with a magnetoactive dielectric

Conclusions

Thus, our investigation shows that the character of the instability of an electron beam in a waveguide depends significantly on the state of the magnetization of the ferrite. Thus, in the case of an unsaturated ferrite the spectrum of the excited oscillations is unbounded, in contrast to the case of a longitudinally magnetized ferrite, when the spectrum of the waveguide harmonics is bounded by the frequency$\omega _p = (1.76 \cdot 10^7 )\sqrt {B_0 H_0 .}$

In the case of gyrotropic ferrite waveguide, the frequencies of the excited oscillations increase with increasing longitudinal magnetic field$\sim \sqrt {H_0 }$ [see formula (21)], as is well confirmed by measurement results [8].

The development of instability leads to a redistribution of the energy over the length of the beam (this effect was observed in experiment [8]), so that ferrite waveguides can be used for self-acceleration of intense electron beams.