PURPOSE: To discharge electrons efficiently and reliably by using a gap between two electrode plates as an electron passage, providing an electron source on one end of the electron passage and an extracting electrode on the other end respectively, and making the potential applied to the extracting electrode higher than that applied to the electron source side between the electrode units.
CONSTITUTION: An electron source 24 such as a heater is provided on one end of an electron passage 22, and an extracting electrode 25 is provided on the other end. The potential is applied to individual metal electrode units 19, and the potential is adjusted so as to be smaller for the unit 19 at a position near the extracting electrode 25 by using resisters R1WR5. Electrons emitted from the electron source 24 first hit U1, and secondary electrons are emitted fron U1, secondary electrons are emitted amplifiably from D1→U2→D2→U3→D3 in sequence, and discharged through the electron passage 22 of the extracting electrode 25 side. Accordingly, the number of emitted electrons is increased as the number of collisions with metal electrode units of electrons is increased, and a large quantity of electrons can be discharged at one time.
KUMAKIRI TADASHI
AKARI KOUICHIROU
Next Patent: SCAN TYPE TUNNEL MICROSCOPE