| Abstract: | On the basis of a physical notions of the specific features of the slow-wave field distribution in the helix structure of
a traveling-wave tube (TWT), various methods for controlling the amount of wave slowing and the slope of the dispersion characteristic
are analyzed. The effect of the dielectric supports and correcting elements placed outside the helix is considered. In addition
to the known methods for correcting dispersion through the use of a dielectric shield and longitudinally conducting elements,
which weaken the interaction with the electron flow, new methods that provide both an efficient interaction with the electrons
and the possibility of operation without backward-wave self-excitation at voltages higher than the voltages used with conventional
helices are proposed and analyzed. With an analysis based on the equivalent-line method, it is shown that the slope of the
helix dispersion characteristic can be decreased by the appropriate use of ring-shaped supports. Design solutions using the
new methods of correction are considered. The history of development of ultrabroadband TWTs, including the work done in the
Soviet Union on tubes with centrifugal electrostatic focusing, whose actual amplification band can be as wide as three octaves,
is partially presented. |
