GALLIUM ION SOURCE

PROBLEM TO BE SOLVED: To prevent the separation of a needle electrode from a filament under storage or transportation and even in long use and can use without anxiety by combining W-Re, or W-Re and W as the materials of the filament and the needle electrode. SOLUTION: Metal powder 7 is put on the joining part of a needle electrode 1 and a filament 4, and sintered. The metal powder 7 is applied to the joining part so as to cover it, then sintered. As the metal powder 7, a suitable metal has the melting point with no trouble even in the heat treatment receiving in the practical use of a gallium ion source, sinters in the melting point or lower of the filament 4 and hardly generates gas under the conditions of the practical use. For example, W and Ta are preferable among the high melting point metals such as W, Ta, Mo, or the like. Regarding to the material of the metal plate 7, W, W-Re, Ta are especially preferable from the standpoint of the melting point with no trouble in the heat treatment receiving in the practical use of the gallium ion source and good wettability to gallium among W, W-Re, Ta, Mo, Re, or the like.