ABSTRACT
Emitter shape is an important parameter for performance of the source, because it affects the field strength at its surface and the lens effect between the emitter and the extractor. The shape is, however, generally not in thermodynamic equilibrium, and as a consequence the source can evolve and display a performance that is not constant in time. Shape changes become particularly important when probe properties need to be constant over a long time period (lithography applications) and/or when a larger area of the end facet is of interest, such as for multibeam applications (Zhang & Kruit, 2007; Young et al., 2009). Below we will address different consequences of thermodynamic instability: collapsing of the end facet, and other geometry changes of the end facet, and changes of the emitter on a larger scale-the overall size of the tip-and how this affects source performance.
