Radioactive decays of stored highly charged ions

Decay properties known in neutral atoms can be altered significantly if all or most bound electrons are removed. Straightforwardly, in fully-ionised nuclei, the decay channels involving electrons are simply disabled. Also decay modes, that are hindered or completely blocked in neutral atoms, may, respectively, become dominant or open up in highly charged ions. Few-electron ions are by themselves clean systems with well-defined quantum numbers, in which the interactions within the remaining electrons can either be excluded or treated precisely, thereby allowing for investigations of the influence of atomic shell on nuclear decay properties. Violent stellar environments characterised by high temperatures and densities lead to high ionisation degrees of nuclides involved in nucleosynthesis processes. In spite of the rich motivation for studying radioactive decays of highly charged ions, intensive measurements became possible only after heavy-ion storage rings coupled to radioactive-ion beam facilities became available. Presented here is a compact review of the relevant experimental techniques and experiments.