Reproduction in the cattle egret (Bubulcus ibis ibis): The function of breeding plumes

A method for manufacturing an anode structure used for a magnetron from metal stock, by which the peripheral wall and the inner vanes of the anode are integrally constructed, the said method comprising three steps, that is: the step of forming a primary workpiece consisting of a thick cylindrical wall and a thick disk-like part closing the cylinder in its axially mid portion, the step of forming a secondary workpiece from the primary workpiece by a warm extruding process so that the secondary workpiece has a plurality of radial vanes integral with the cylindrical wall and extending radially inward from the wall, and a step of removing the remaining portion of the disk-like part bridging the bottom ends of the vanes.