ABSTRACT
This chapter provides an introduction to the liquid metal ion source (LMIS) and the physics of how it works. More generally, the behavior of a LMIS depends on a complex interplay between electrohydrodynamic effects on the liquid ionizant supply and ion emission and space-charge effects. Although the emission mechanism will presumably be some form of field desorption, rather than field evaporation, aspects of its theory will be similar to LMIS theory. The chapter deals with relevant basic science, develops the theory of the so-called metallic Gilbert-Gray cone-jet, and shows how relevant LMIS operational and ion-optical properties relate to those of the cone-jet. Formation of a liquid cone is essential to the normal LMIS but is a more general liquid phenomenon. For LMIS theory, an important question is whether the escape mechanism is the image-hump mechanism or a charge-exchange-type mechanism.
