HITRAP is a planned ion trap facility which is designed for capturing and cooling of highly charged ions (HCI) produced at the GSI-accelerator complex. In the HITRAP facility heavy highly charged ions will be available as bare nuclei (up to uranium U92+), hydrogen-like ions or few-electron systems at low temperatures. Highly charged ions are accelerated in the heavy-ion synchrotron SIS, stripped in a foil to the desired charge state and injected into the storage ring ESR. In the ESR the ions will be decelerated to an energy of 3 MeV/u. They are then extracted in a fast-extraction mode as short ion bunches, are decelerated and cooled to helium temperatures in Penning traps.
With this novel technique of deceleration, trapping and cooling of highly charged ions, atomic physics studies on slow HCI up to bare uranium interacting with photons, atoms, molecules, clusters, surfaces, and solids will be performed. In addition to collision studies, high-accuracy atomic physics experiments on trapped HCI are part of the atomic physics program of the HITRAP facility at the ESR. As examples, the measurement of the g-factor of a bound electron in hydrogen-like ions will provide a further stringent test of strong field QED calculations and high-accuracy mass spectrometry will allow for a precise determination of atomic binding energies in few-electron systems. The technological experience of deceleration, trapping and cooling of HCI, which will be gained at the HITRAP facility, will be employed for a similar trap facility at the future storage ring NESR.