While at MIT he helped develop and maintain a superb theory program, that has made many outstanding contributions to magnetic fusion energy research, and enhanced the visibility of the Plasma Science and Fusion Center (PSFC) and its Alcator C-Mod experimental program in the world fusion community. During his years at MIT and Oak Ridge National Laboratory, Dr. Sigmar made important contributions to the understanding of collisional transport in tokamaks and the behavior of alpha particles in fusing plasmas, and played a leadership role in the development of an edge and divertor physics program in the U. S. fusion effort.
Dr. Sigmar retired from MIT in 2001 because of ill health. Upon his retirement, the Department of Energy recognized Dr. Sigmar's efforts on behalf of magnetic fusion by presenting him with a Distinguished Associate Award. The citation read as follows. "For your contributions to our understanding of plasma confinement, the physics of burning plasmas, and the role of the plasma edge, and your untiring efforts which have enhanced the standing of the MIT Plasma Science and Fusion Center as a major intellectual center for plasma physics research. Your commitment to international fusion collaboration and stimulation of theory programs around the world has been critical to our progress in fusion science research."
Dr. Sigmar received his PhD in 1965 from the Technical University of Vienna and came to MIT as a postdoctoral fellow in the Physics Department working with Professor Bruno Coppi and stayed on as a Associate Professor in the Nuclear Engineering Department until 1976. For the next eleven years he worked at the Oak Ridge National Laboratory where he became the Associate Head of Theory. He returned to MIT in 1985 where at various times served as Head of Theory, Acting Director, and Deputy Director of the PSFC while maintaining his ties to the Nuclear Engineering Department. His distinguished service to MIT spanned twenty years altogether.During his first stay MIT Dr. Sigmar did seminal work on collisional transport in tokamaks, including a classic review article with Dr. Steven Hirshman on the role of impurities. Collisional transport remained an interest, even during retirement, and is the subject of a superb textbook he co-authored with Dr. Per Helander. While at ORNL and then as Theory Head at the PSFC he pursued his interest in the role of alpha particles in burning tokamak plasmas. He energized the national and international fusion communities to focus their attention on stability and transport issues associated with fast particles, and to develop techniques to observe alpha particle related phenomena in present experiments. While Acting Director of the PSFC he realized that the U.S. edge physics program needed strengthening because of the increasingly important role of the edge region and the need for a divertor at the edge of a tokamak reactor to handle the heat load. He responded by establishing a divertor physics program at the PSFC and was then elected as Head of the U.S. Divertor Task Force. His work and the work of other members of the Task Force provided many new insights into our present understanding of divertor operation and developed important capabilities in the numerical modeling of divertors. Both the alpha particle and divertor research efforts at the PSFC led to productive collaborations with the international fusion communities. These research endeavors are now considered crucial aspects of the current U.S. and world fusion programs as they head towards their goal of building the International Thermonuclear Experimental Reactor (ITER).
Dr. Sigmar was made a Fellow of the American Physical Society in 1979. He was also a member of the American Nuclear Society and the Austrian Physical Society. He was appointed A. O. Professor of Plasma Physics at the Technical University of Vienna in 1981 and in 1996 was elected a Corresponding Member of the Austrian Academy of Science. He established theory exchanges between MIT and Chalmers University of Technology in Sweden and the Culham Laboratory in England and fostered U.S. collaboration with Russian and Japanese scientists. As a result of his pioneering work on alpha particle theory, he served on the Tokamak Fusion Test Reactor Deuterium-Tritium Program Advisory Committee and was a co-organizer of an international alpha particle workshop. He served on many other DOE committees including the Theory Coordinating Committee and the U. S. ITER Steering Committee, was a member of the Board of Editors for the plasma physics journals Nuclear Fusion (10 years) and Physics of Fluids (4 years), and helped organize several other national and international meetings. Dieter will be greatly missed by his many friends and colleagues.
Expressions of sympathy may be sent to his wife, Lisl,at 21921 Mockingbird Street, Lago Vista, TX 78645 USA