Over-mode slow wave structure and traveling wave tube

The invention relates to an over-mode slow wave structure and a traveling wave tube. The over-mode slow wave structure comprises a first periodic waveguide and a second periodic waveguide which are oppositely arranged; in the first direction, the opposite end faces of the first periodic waveguide and the second periodic waveguide are end faces with periodical change fluctuation. The trough part of the first periodic waveguide is provided with a first opening and a second opening, the crest part of the second periodic waveguide is provided with a third opening and a fourth opening, and the first opening and the third opening are oppositely arranged; each first opening and each third opening are communicated in the first direction to form a first strip-shaped electron beam channel; the second openings and the fourth openings are oppositely arranged, and the second openings and the fourth openings are communicated in the first direction to form a second strip electron beam channel. By adopting the over-mode slow