The Solution of Power Holes in Helix Traveling-Wave Tube

The saturated output power of a helix traveling-wave tube(TWT) can show unexpected dips in certain narrow frequency ranges.These dips,commonly called "powe holes",can have serious consequences on the performance of the system,especially for communication applications.This paper explains the reason of "power holes" and introduce a possible solution-tapering the focusing magnetic field.Computer simulation has been done by a 2D large signal helix TWT code.The results show that this method can suppress the power holes to a certain extent.The saturated output power versus drive frequency curve is smoothed over the entire operating bandwidth.