Testing atomic structure theories with high-accuracy mass measurements on highly charged ions

The mass of a highly charged ion is the sum of the mass of the nucleus, the mass of the electrons and the electronic binding energies. High-accuracy m ass measurements on highly charged ions in a sequence of different charge s tates yield informations on atomic binding energies, i.e., the ionisation p otentials. In our contribution we discuss the possibility of determining at omic binding energies of highly charged ions to better than 20 eV via cyclo tron frequency measurements in a Penning trap. At this level of accuracy di fferent contributions to the binding energies, like relativistic correction s, Breit corrections and QED corrections, can be measured.