ANTHONY EMERSON (Bertie) ROBSON was born to Arnold Emerson and Mary Primrose Gillingham Robson in London, England, March 29, 1932. Their only son, he was evacuated from London in September 1940 at the height of the London Blitz and spent the rest of the war in rural Cornwall. He attended Exeter School, Exeter, Devon from 1945 to 1949 when he entered Exeter College, Oxford as an Open Scholar and earned a B. A. in Physics (First Class) in 1952. In 1953, he enrolled in Oxford’s new graduate college, St. Antony’s (founded 1950) from which he completed his D. Phil in Physics in 1956 under the supervision of the celebrated physicist, A. H. von Engel. Von Engel’s textbook Ionized Gases (Clarendon Press, 1955) was essential reading for early experimental plasma physicists and Robson attributes his knowledge of the subject to having been required to proofread the text. Robson’s dissertation was entitled, A Study of Some Phenomena of Arc Discharges and contained a new theory of the cathode mechanism and an experimental study of the “retrograde motion” (in which an arc at low pressure goes backwards in a transverse magnetic field).
In 1956, following completion of his degree, Bertie joined the Atomic Energy Research Establishment at Harwell, Berkshire, as part of the British fusion program which was centered at that time on the large toroidal pinch machine, ZETA. He was given the problem of plasma-solid interactions and, in the course of this work he discovered the unipolar arc, an arc between a metal surface and a plasma in contact with it. Such an arc requires only one electrode and is maintained by the thermal energy of the electrons and; he and P. C. Thonemann provided the explanation. Unipolar arcs were a serious and unexpected source of contamination in ZETA.
Inspired by the patterns of arc tracks on the walls of ZETA, Bertie extended his thesis work and studied the motion of arc spots in fields with a component normal to the surface. This gives rise to a lateral component of the motion which has since become known as ‘Robson Drift.’
It was at Harwell that Bertie became interested in alternative approaches to fusion, in particular, the mirror machine. This approach depends on the adiabatic invariance of ion orbits to reflect ions from regions of increasing magnetic field (the “mirrors”) and Bertie designed and built a large mirror machine in which the adiabatic condition was deliberately violated, allowing molecular ions to be injected through the mirrors and trapped long enough for them to be converted into atomic ions, which were then adiabatically trapped. This experiment produced initial results demonstrating the principle in 1965, but by then, the emphasis in mirror research had changed to the ‘minimum-B’ concept and at the same time it was decided to move the British fusion work to the new laboratory at Culham, Oxfordshire.
In early 1966, Bertie moved to the Culham Laboratory, where he did theoretical studies of alternate fusion concepts, none of which was developed into a program, and in September 1966, he took a year’s leave of absence to join Roy Bickerton at the invitation of Bill Drummond to initiate an experimental fusion program in the University of Texas Department of Physics. At the end of his year’s leave, Roy Bickerton went home, but Bertie decided to stay. In collaboration with John Sheffield, also from Culham, he carried out experiments on oblique collisionless shocks and anomalously fast penetration of magnetic fields into plasma. Then, following his inclination to ‘do things differently’ he designed and built a novel turbulently heated tokamak which established UT as a serious player in experimental fusion research. (Robson and Texas Tokamak at right.)
In 1972, now a naturalized citizen, Bertie joined the Naval Research Laboratory in Washington, D. C., where he was Controlled Fusion Research Co-ordinator and Head of the Experimental Plasma Physics Branch. There his work was devoted to theory and experiments on alternate fusion concepts with particular emphasis on naval propulsion. His first interest was the LINUS imploding liner concept, proposed by Boris and Shanny, in which plasma was to be compressed to fusion conditions by imploding liners, and sections of his branch performed experiments which produced megagauss magnetic fields with imploding liquid metals and also studied ways of creating initial plasma suitable for compression. These included rotating relativistic electron beams and free-falling frozen deuterium pellets ionized and heated by lasers. At the same time Bertie pursued pulsed power development, especially inductive storage, and designed and built a novel high-speed homopolar generator.
As with so many alternate fusion concepts, the extrapolation of the original LINUS concept to the design of a working reactor revealed serious practical problems, and Bertie moved on to another concept, the Dense Z-Pinch. In collaboration with John Sethian he investigated the creation of pinches from hair-like fibers of frozen deuterium and found that they showed remarkable stability if the current was rising sufficiently rapidly (at kA/ns). He conceived a very compact fusion reactor based on this principle but, again, found that the combination of physics and engineering problems made it unlikely that it could be successfully developed.
As a diversion from fusion research, and as a contribution to the festschrift (J. Phys. D. 1978) honoring von Engel's 80th birthday, Bertie used the NRL High Field Magnet Facility to drive low-pressure arcs in fields of up to 5T. He showed for the first time that in high fields, the arc motion went from the retrograde to the Amperian direction, as predicted by the theory put forward in his thesis, but which he could not test at the time because such high fields were not available to him.
In 1989, Bertie was made an NRL Senior Scientist, continuing to examine alternate fusion concepts as well as working on various plasma physics problems of interest to the Navy. One of these was the so-called ‘agile mirror’ in which microwaves were reflected from a pulsed plasma sheet as a possible director for a radar system. He retired from NRL in 1994.
Bertie then joined Berkeley Scholars Incorporated of Springfield, Virginia, working on problems of plasma physics of interest to the Navy. He was involved with a consortium of NRL, RTI (Research Triangle Institute) and 3M to develop diamond synthesis by plasma vapor deposition and applied his experience with ZETA at Harwell to design reaction chambers for r.f. discharges operating continuously at 300 kW.
In 2004, Bertie became an independent consultant working mainly with the NRL High Average Power Laser (HAPL) Program, a multi-disciplinary effort to develop a fusion concept based on direct-drive implosion of DT targets by KrF lasers. Bertie’s principal contribution was to show how the inner walls of the reaction chamber might be shielded from the reaction products by the use of magnetic fields, applying ideas developed in magnetic fusion research to the problems of inertial fusion. In the course of this work, he became convinced that direct-drive inertial fusion offered a better chance of achieving practical fusion than the mainstream tokamak approach.
As of 2011, Bertie continues to work on inertial fusion problems, in particular the development of Electra, the large, repetitively pulsed KrF laser at NRL.
Bertie and Elizabeth Robson (sic) were married in 1961. They had four children, Mark, Caitlin, Ian and James, two of whom (Caitlin and Ian) graduated from the University of Texas at Austin. After his divorce, Bertie married Patricia Anne Scott on May 1, 1976, in Fairfax, Virginia. Patricia was the daughter of Norman Leroy and Blanche Emma Cote Scott. Betie and Patricia lived in Troy, Virginia until her death. He is a Fellow of the American Physical Society and has served on the editorial board of the journal Plasma Physics and Controlled Fusion.
Photo above was taken during a visit by Lev Artsimovich, "Soviet scientist and "father of the tokamak". Bertie Robson is to his right and Alan Ware is on his left. The photo was taken in the Tokamak bay.)
Collisionles Shock Experiment Photo Album