Norman Rostoker was a nuclear fusion pioneer and “somewhat a renegade” (to quote him) advocate of research independent of the Department of Energy. He co-founded Tri Alpha Energy to advance work in magnetic field-reversed containment methods and died Dec. 25, 2014 as that company was building its third generation machine.
Rostoker was born Aug. 16, 1925, in Toronto, Canada, and earned a master’s degree at the University of Toronto in 1947. He received a D.Sc. in 1950 from the Carnegie Institute of Technology and was on the scientific staff there until 1953. His early work on electrical resistivity of the earth in 1950 had widespread impact. Modern petroleum prospecting with low frequency electromagnetic waves uses, and expands upon, the physics in John Bardeen's and Rostoker's work very productively.
In 1954 he added to the Korringa-Kohn-Rostoker method, still widely used in calculating the electronic band structure in solids. He pioneered theories of the statistical mechanics of particles with Coulomb interactions and to the treatment of inhomogeneities, fluctuations and Larmor radius effects in plasmas. He carried forward from his solid state work by translating the test particle method into plasma physics, whereby a gas of charged particles can be considered as a collection of “dressed” particles in which each individual particle is surrounded by its own shielding cloud. This simplifies basic property calculations and especially particle-in-cell simulations.
This work led him into the practical side of plasma fusion research. Through this evolution he worked at the Armour Research Foundation, the Illinois Institute of Technology and General Atomics, before joining the faculty at UC San Diego in 1962. He became the IBM Professor of Engineering at Cornell University in 1967 and in 1972 joined UC Irvine, chairing the department.
Rostoker cared deeply about using clean fusion as a source of almost unlimited, nonpolluting energy for human development. As soon as he had established the theoretical foundation for the technology, he turned his attention to its realization.
Rostoker’s forte was applying theory to physics and engineering technology at the forefront of fusion reactor development. Among the first generation of fusion pioneers, Rostoker early saw the simplicity of field-reversed magnetic confinement geometries. Magnetic “bottles” are effective if the field lines do not penetrate solid surfaces, closing on themselves into circles or toroidal surfaces. The mainline confinement concepts of like tokomaks do this in a toroidal chamber, allowing control over the magnetic configuration, but demanding very complex construction. In field-reversed configurations field lines are closed, providing good confinement, but the chamber is cylindrical, allowing easy construction and maintenance. The anomalous transport characteristic of tokamaks can be avoided and a compact reactor design becomes viable.
At UCI, Rostoker pursued using collective plasma fields to assist in ion acceleration and to build the currents that shape a field-reversed geometry; in this alone he held 27 U.S. patents. His laboratory focused on devising new approaches to the central fusion problems, translating theory into hardware.
Fusion demands extremely high-energy ions. Rostoker’s most important insight was that high-energy, large-orbit particles like those in accelerators are able to “ride over” disruptive plasma turbulence by averaging their effects to nearly zero. This can overcome various plasma instabilities that hamper other designs. Another of Rostoker’s goals was to develop a fusion reactor that does not suffer from degradation of its surrounding structure by neutron capture, by using the boron-proton fusion reaction.
In addition to his outstanding academic career in plasma and solid-state physics, he was a tenacious entrepreneur, pushing the envelope of technology frontier through private companies in the areas of high-power accelerators and clean fusion energy generation. “He excelled at the ‘never surrender’ notion,” his student Michl Binderbauer noted. Rostoker’s group at UC Irvine then spun off Tri Alpha Energy, to carry the work further. Unable to gain enough funding from the Department of Energy, Rostoker thereafter kept the company independent of such support. He instituted a Chair in this field in 2012 at UCI.
Rostoker was married for 65 years to Helen Corinne Rostoker, who died earlier in 2014, and is survived by their four children, Stephen Rostoker, Ruth Forton, Linda Rostoker and Rachel Uchizono, as well as grandchildren Lisa Servedio, Nolan Uchizono and Kellen Uchizono, and one great-grandchild, Sofia Servedio.
Gregory Benford
Physics, UC Irvine
