Experimental tests of QED in strong central fields

Quantum-electrodynamic (QED) influences of strong atomic fields on the structure of highly-charged, heavy ions are investigated. A survey on the present experimental status and the recent achievements in this field is given concentrating on the heaviest few-electron systems. The experimental techniques, from the different X-ray spectroscopy techniques (nondispersive, dispersive, and absorber edge methods) via VUV spectroscopy to collision methods (like dielectronic recombination or Q-value measurements) are discussed and possible future developments and prospects are outlined