Vacuum cavity

The utility model relates to a vacuum cavity. A top plate is arranged above the vacuum cavity; a bottom plate is arranged below the vacuum cavity; an air exhaust interface flange is arranged on the central axis of the top plate and the bottom plate; a cavity upper door frame is arranged on one side of the vacuum cavity; the vacuum cavity is divided into a semicircle by the cavity upper door frame; a plurality of cavity side wall structures are arranged on the two sides of the air exhaust interface flange along the edges of the top plate and the bottom plate; and a cavity side wall welding flange is arranged between the cavity side wall structures. The cavity side wall welding flange and the cavity side wall structure are obtained by bending firstly, the cavity side wall welding flange and the cavity side wall structure can be prefabricated, and the whole semicircular cavity structure is divided into a plurality of blocks; and the flange is not required to be welded on the side wall of the cavity after the wel