HIGH POTENTIAL GRADIENT TYPE SINGLE-GAP ACCELERATION TUBE

PROBLEM TO BE SOLVED: To provide a small-sized and high-energy high potential gradient type single-gap acceleration tube in which an extremely high reduction rate that cannot be obtained in a conventional acceleration tube can be obtained, discharge is prevented from being generated even when a high voltage is applied and an aberration coefficient that causes aberration is relatively small and which simultaneously performs acceleration and convergence, an application thereof and a gas nanobeam forming device employing the acceleration tube.SOLUTION: An anode electrode of an acceleration tube is an electrode, the cross section of which is L-shaped, formed from a vertical piece parallel with an axis of ion beams and a horizontal piece vertical to the axis, a distal end of the vertical piece extends toward a cathode electrode, and a distal end of the horizontal piece is fixed to an insulator. A plurality of intermediate electrodes include cross sections which are L-shaped similarly to the anode electrode, and are disposed while opposing the cathode electrode in such a manner that distal ends of vertical pieces form electric fields between the intermediate electrodes and the cathode electrode, and distal ends of horizontal pieces are fixed to the insulator.