Interchange, quasi-interchange, ballooning modes: What is their exact definition?



Some confusion appears to remain among those in the magnetospheric community regarding the concepts of interchange, quasi-interchange, and ballooning. By placing these different kinds of motions in the broader framework of a unified, comprehensive formalism on ideal magnetohydrodynamic (MHD) modes and by making the link with the disparate results of several famous and often-quoted studies in the field, we can clarify this situation.