ELECTRON-EMITTING DEVICE

PROBLEM TO BE SOLVED: To add durability to a thermoelectron generating source for emitting a lorge number of electrons by filling a recessed part formed in a surface of an electron-emitting part with an aggregate of cylindrical carbon nano-tubes, and by providing an electron extraction electrode on the electron emission side of the electron-emitting part. SOLUTION: An electron-emitting device has a movable stage 102 which can move in the XY-directions on its base table 101. A negative electrode 103 having an electron emission part 103a at its tip is placed on the movable stage 102, and an extraction electrode 104 is arranged on an extension part of the tip of the negative electrode 103 in a condition in which it is fixed to the base table 101. A plurality of recessed parts 111 are formed in the electron-emitting part 103a, and an aggregate of cylindrical carbon nano-tubes is filled into it. For example, a plurality of graphite columns with about 10 μm length are filled in the same direction in a condition in which they are bundled. An aperture 104a is formed in the extraction electrode 104, moving and by the movable stage 102 controls position and direction of the tip of the negative electrode 103 is controlled so as to have the electron extraction efficiency optimized.