Dieter Gruen - Fusion Research

Fusion Research

Gruen became interested in the challenging materials problems associated with attempts to harness here on earth the fusion reactions that power the sun. Among these problems is the introduction of metal impurities into the thermonuclear plasma by sputtering processes of the metal walls surrounding the plasma. He conceived the idea of using laser fluorescence spectroscopy to determine the kind and quantity of sputtered metal atoms and to gain fundamental insights into the energetics and depth of origin of the sputtered species. The basic findings emanating from these experiments made possible the use of laser fluorescence as a powerful plasma diagnostic technique. These early laser fluorescence methods evolved under his leadership into a highly sensitive new surface science technique called SARISA: Surface Analysis by Resonance Ionization of Sputtered Atoms. Recent measurements using an advanced form of this apparatus have been made by his colleague Michael J. Pellin (B.S., Northwestern University; Ph.D., University of Illinois). These have yielded isotope ratios of heavy elements in presolar SiC grains found in meteorites, data that are important for an understanding of the origin of the presolar nebula from which the sun condensed five billion years ago.