(b)
Fig 2 The complete tube with periodic dielectric-loaded
structure and its output power. (a)the complete tube, (b) simulation and
test.
The analysis of mode competition is an important part of the study of
the performance of high-frequency interaction structures. Figure 3 shows
the dispersion curves of
different waveguide modes and electron cyclotron resonant curves, the
dispersion curve of the working mode TE21 and the
electron cyclotron resonant curve when s=2 are tangent to point C, where
the tangent magnetic field Bg=5190 Gauss; At the same
time, there are intersections between the dispersion curves of the
TE31 and TE41 modes and the electron
cyclotron resonant curves in the region of negative axis
(kz<0), that are the two points A and B in the
figure, which may cause return oscillation, and the corresponding
starting frequency points are 36.56 GHz and 46.56 GHz, respectively.
Therefore, the suppression of the main competitive mode
TE31 and TE41 mode is the key to
designing second harmonic TE21 gyro-TWTs.