| 摘要 |
PURPOSE:To generate a stable ion beam for long hours by forming at least a surface part of a needle-shaped member with a metal comprising an alloy able to be ionized. CONSTITUTION:A heatig current is fed between stems 11 and 12 from a heating electric power supply and along with heating of a filament, an alloy 2 inside of a reservoir 1 is heated to be liquidized when heated up above the melting point of said alloy Pt-B and passes through a thin hole 5 on the bottom of the reservoir 1 due to a strong electric field at the tip part of a needle-shaped member 6 to be pulled out up to the tip part of the needle-shaped member. However, as platinum is used for the needle-shaped member 6, the platinum on the surface of said member does not dissolve in the liquid alloy even when the eutectic alloy Pt-B based on said platinum is liquidized. Accordingly, the constitution ratio of the liquid alloy does not change inspite of use for long hours so that the alloy is stably fed to the tip of the needle shaped member 6 without being solidified so far as the heating temperature is above a fixed temperature. |
