Atomic Structure of HCI

An EBIT is well suited as a source for high resolution spectroscopy of highly charged ions. The ions are at rest to a good approximation, having no centre-of-mass velocity so a Doppler correction does not need to be applied.
In the atomic structure of HCIs, the relativistic and quantum electro-dynamics (QED) contributions are very important compared with that of neutral atoms and low charged ions. For instance, the Lamb shift in hydrogenlike ions increases in proportion to Z4 while the elctronic binding energies increase only as Z2, so that the relative contribution of the Lamb shift increases as Z. Precise measurement of the energy levels of HCIs, then, gives a test of
QED theory in the strong field regime.