Abstract. Results of theoretical
analysis of a Gyro-TWT with helically corrugated waveguide of 10-mm wavelength
range are presented. The peculiarities of the presented Gyro-TWT variety are
the use of a single barrier dielectric window (both for input and output of the
microwave radiation), “warm” magnet with a power consumption of about 15 kW, as
well as a relatively low-voltage (25 kV*2 A) DC power supply. Construction and
technology of the manufacturing of such an amplifier appear to be quite similar
to those of so-called technological gyrotron-oscillators that are reliable
devices and used for numerous applications. 3D full electromagnetic computer
modeling of the most important part of the device starting from the emitter of
an electron beam and ending by significant downturn of the axial magnetic field
bordering the beam-wave interaction space was performed for the first time. At
the input power in the range of 10-50 W, the gyro-TWT was simulated to yield
the output power of about 10 kW at the instantaneous bandwidth of 1 GHz or 3-5 kW
at the bandwidth of 2 GHz depending on the tuning of the static magnetic field.
The system was analyzed with respect to the most expected 3D imperfection in
the form of the cathode axis radial shift. It was found that the critical axis
shift amounted to about 0.5 mm at which the bandwidth was significantly reduced
and the amplifier could start to oscillate.
Key words: gyrotron-type device, gyrotron
travelling-wave tube, gyro-TWT, gyro-TWT with helically corrugated waveguide,
3D Finite-Difference Time-Domain Particle-in-Cell (FDTD PIC) simulations.
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