THE STATE OF THE METAL-FILM COVERING THE NEEDLE OF A LIQUID-METAL INDIUM ION-SOURCE

The macroscopic description of a needle LMIS as a free flowing film of molten metal adhering to the central needle has to be modified. ft is shown for the case of the indium LMIS that redeposition (contaminatio n) of sputtered electrode material on the LMIS surface leads to the fo rmation of a solid surface film. Liquid indium is flowing towards the needle apex in an annular gap between the contamination film and centr al needle. The apex region remains clear from contamination and leaves room for formation of a Taylor cone. This new realistic model explain s phenomena observed in short- and long-time operation of single-tip a nd multi-tip indium ion emitter modules.