STORING METHOD FOR FIELD EMISSION TYPE GALLIUM CHARGED PARTICLE SOURCE

PURPOSE:To make a field emission type gallium charged particle source easily storable and transportable by cooling said particle source to be at a freezing point temperature of this gallium or below this temperature and freezing the source and next keeping the temperature of the source less than a melting point temperature. CONSTITUTION:After a field emission type gallium charged particle source shown in a figure is used, it is first located statically for about three hours in a freezer of -13 deg.C so as to freeze gallium 3 in a storage part 2. According to the result that a tip of a needle electrode 1 has been observed by a scanning type electronic microscope after the gallium was freezed, a shape of a gallium cone 10 is kept ideal as shown in the figure. The particle source with such freezed gallium 3 is supported inside a hard plastic container. The container is surrounded with a cushion material and packed together with Dry Ice lump in a corrugated cardboard box and next transported to a remote place by a truck. As to the particle source whose transportation is finished, the gallium 3 is maintained on a solid state, and the shape of the gallium cone 10 is normal, and damage such as protrusion of the gallium 3 does not appear at all.