Richard Freeman Post

Richard Freeman Post, one of three founders of magnetic fusion energy research in the U.S., passed away April 7, 2015. He was 96. Dick Post also pioneered the electromechanical battery utilizing high-speed flywheel energy storage, stabilized by his magnetic bearing design later employed to stabilize magnetically levitated trains. He was among the first recipients of the American Physical Society’s Maxwell Prize, in 1978.

Post was a prolific inventor with 34 patents, 9 issued after age 90. As leader of mirror fusion research and later Deputy Associate Director for Magnetic Fusion Energy at the Lawrence Livermore National Laboratory, Dick contributed three seminal ideas that culminated in the first demonstration of a plasma at thermonuclear temperatures, in the 2XIIB experiment in 1976. These ideas were: (1) the Yin Yang magnetic mirror design providing MHD stability; (2) 20 KeV neutral beam injectors to create a plasma, with a million times more current than earlier versions; and (3) the theoretical discovery, with Marshall Rosenbluth, of the Drift-Cyclotron-Loss-Cone microinstability mechanism of plasma leakage in mirror machines and the way to stabilize it by cold plasma injection. He also invented a method for Direct Conversion of plasma energy to electricity as a way to improve the efficiency of mirror fusion reactors.

His review papers published in 1956 in Reviews of Modern Physics and in 1959 in Annual Review of Nuclear Science were among the first consistent reviews of hot plasmas for controlled fusion. These influential papers were immediately translated into Russian and published in Russia, the 1959 paper as a separate book. In 1987, he published a comprehensive review of mirror research, essentially, a book that filled the whole October issue of “Nuclear Fusion”. Despite termination of the mirror program in USA, he firmly believed that the mirror fusion approach with different physics and engineering advantages was still worth pursuing. He remained actively engaged in mirror research and in early 2000 came up with an idea of a “kinetic stabilizer” for axisymmetric tandem mirrors. At present, there are sizable groups working on mirrors in Russia and China.

Dick’s work on magnetically-levitated trains was based on the idea that both levitation and propulsion would be provided by simple electrical circuits embedded into the track, whereas the cars will have only “passive” magnetic structures made of specially arranged permanent magnets (“Halbach arrays”). Not requiring superconductors, this approach has been actively pursued and in 2004 it was recognized by a R&D 100 Award. This work continues, for possible use as a launch system.

Equally innovative were his studies of magnetic bearings where, by a creative use of magnet arrays he found geometries where the bearing would be passively stable, without any need for complicated feed-back stabilization. These magnetic bearings are an integral part of the novel, high-speed energy storage systems that have been developed by Dick.

Dick Post was born in Pomona, California, November 14, 1918, and graduated from Pomona College in 1940. After employment at the Naval Research Laboratory, he received his Ph. D. in physics from Stanford University in 1951, and joined the Livermore lab in 1952, just months after it opened. He continued working part-time at Livermore after retirement in 1994, and was able to work there until the last week before he died.

Dick was the epitome of a “gentleman.” He had many friends and followers in the international fusion community. He loved the Swiss Alps. Until recent years he and his wife Marylee would spend one summer month in Switzerland. He became proficient in German and could read originals of German novels.

T. Kenneth Fowler, University of California, Berkeley
Dmitri Ryutov, Lawrence Livermore National Laboratory

Reference:

R. F. Post. “The magnetic mirror approach to fusion.” NUCLEAR FUSION Volume: 27 Issue: 10 Pages: 1579-1731 Published: OCT 1987, doi:10.1088/0029-5515/27/10/001 .