  We propose a method for quantifying charge-driven instabilities in clusters,
based on equilibrium simulations under confinement at constant external
pressure. This approach makes no assumptions about the mode of decay and allows
different clusters to be compared on an equal footing. A comprehensive survey
of stability in model clusters of 309 Lennard-Jones particles augmented with
Coulomb interactions is presented. We proceed to examine dynamic signatures of
instability, finding that rate constants for ejection of charged particles
increase smoothly as a function of total charge with no sudden changes. For
clusters where many particles carry charge, ejection of individual charges
competes with a fission process that leads to more symmetric division of the
cluster into large fragments. The rate constants for fission depend much more
sensitively on total charge than those for ejection of individual particles.
