NEGATIVE ION SOURCE

PROBLEM TO BE SOLVED: To provide a highly efficient and reliable negative ion source which suppresses generated quantity of accelerated electrons, generates high-energy negative ion beams, and allows the high-energy and long-distance transport by imparting favorably converged beams. SOLUTION: The negative ion source has a first electrode 15 in which a plurality of holes 16 to extract negative ions generated in a discharge plasma from a discharge vessel are bored and which contacts with the discharge plasma generated in the discharge vessel; a second electrode 18 in which the same number of holes 21 at the positions corresponding to the plurality of holes 22 of the first electrode are bored, and to which a positive potential vs. the first electrode is impressed; a third electrode 19 in which the same number of holes 22 at the positions corresponding to the plurality of holes 21 of the second electrode are bored; and a fourth electrode 24 in which a slit hole 25 corresponding to the plurality of the holes bored in the first to third electrodes is bored, and which is kept at the earth potential. COPYRIGHT: (C)2006,JPO&NCIPI