Structure and dynamics of few-electron ions in an electron beam ion trap (EBIT)
Our team studies the properties of highly charged ions (HCI) produced with electron beam ion traps (EBIT). Due to the technical challenges implied, only very few laboratories in the world can produce and store such ions having charge states as high as Hg78+, a mercury ion with only two electrons left, or even "naked" U92+ which can currently be trapped in a single device (SuperEBIT at LLNL). The Heidelberg EBIT is one of the three high-energy EBITs in operation, and started working in the year 2001. Since then two more EBITs were built in our group, making a total of three traps running in our laboratory.
Highly charged ions are very common in the universe, since the heaviest bodies are usually at very high temperatures, and atoms loose most of their electrons in those environments. Such ions offer important advantages for basic research in quantum electrodynamics at extreme fields, relativistic atomic structure theory and nuclear size contributions. Fundamental effects grow in size with high powers of the ionic charge state, or Z, thus becoming increasingly dominant and easier to measure. At the same time, less electrons mean that the electronic structure becomes easier to handle for theory. But accurate knowledge of the properties of HCIs is also necessary for the diagnostics of hot astrophysical plasmas and fusion energy research, since theoretical methods currently do not reach the precision currently achieved in experiments.
Different spectroscopic techniques from the x-ray to the visible range, as well as laser spectroscopy, are applied at the Heidelberg EBIT to the study of HCIs. Ions extracted from the trap are also used to investigate collisions processes of highly charged ions with electrons, atoms and molecules. Major projects have also been started to investigate the properties of short-lived radioactive isotopes and to apply the recently developed x-ray free electron laser to ions stored in an EBIT.
Resonant electron-ion recombination
Transportable EBIT for external beam sources
Laser spectroscopy at the Heidelberg-EBIT