Axis coupled double-cycle electron accelerating tube, accelerator and cavity ascending frequency adjusting method

The invention discloses an axis coupled double-cycle electron accelerating tube, an accelerator and a cavity ascending frequency adjusting method. A plurality of accelerating cavities and coupling cavities are alternately arranged in the accelerating tube, axially distributed and radially symmetric about an axis, mutually communicated electron beam holes are formed in radial symmetric lines, convex cone structures radially symmetric about the axis of the accelerating tube are arranged on two end faces of each of the accelerating cavities and/or the coupling cavities and positioned at the outer edges of the electron beam holes, and the axial distance between the two convex cone structures is positively correlated to the latent frequency of the corresponding cavities. The convex cone structures capable of adjusting the latent frequency of the corresponding cavities are arranged in the cavities of the axis coupled double-cycle electron accelerating tube, a new scheme is provided for adjustment of the latent freq