James “Jim” Dungey, a pioneering solar terrestrial scientist, died 9 May 2015 at the age of 92. He is best known for seminal and, at times, almost apocryphal work on magnetospheric phenomena and geospace. He laid the foundation for our current understanding of solar-terrestrial coupling.
Jim was born and grew up in Stamford, Lincolnshire, where his father was a schoolteacher. He got his bachelor’s degree from Cambridge in 1947. During World War II, he worked at British Thompson Houston in Rugby, U.K., on developments for radar.
Upon graduating, Jim stayed at Cambridge to pursue a Ph.D. with Fred Hoyle, who, at the time, was writing a monograph on solar physics. Hoyle had been struck by a concept proposed by Ron Giovanelli of the University of Sydney that magnetic neutral sheets on the Sun could give rise to solar flares.
Jim was asked to look at a different context for the Giovanelli problem and investigate whether the formation of a neutral sheet in the magnetic cavity on the nightside of Earth could produce an aurora. He would work on and off on this problem for much of the rest of his career.
Hoyle and Dungey assumed from the start that there was a substantial solar field present near Earth, itself a revolutionary position to take in Britain in the 1940s. Only Hannes Alfvén had previously made such a suggestion [Alfvén, 1939]. Where the terrestrial field and solar field were opposed, neutral sheets would form on both the sunward and antisunward sides of Earth. Jim concluded that a neutral sheet in such conditions could accelerate plasma in a process now called reconnection.
Where the magnetic field lines from the neutral sheet region met the upper atmosphere of Earth, electrons accelerated by reconnection and guided by the field would generate the aurora, in Jim’s picture. Topologically, it was straightforward to see that the feet of the field lines on which the aurora could be excited would form a ring, the auroral zone, around each pole just as had been long known to exist. He went on to propose that poleward of the zone, “open” field lines would connect Sun and Earth. Equatorward of the zone, “closed” field lines would have both ends connected to Earth.
Today, few people would question Jim’s description. Nonetheless, in the 1950s, his thesis work on magnetic reconnection proved hard to publish. The journal of record for a British researcher at the time was Monthly Notices of the Royal Astronomical Society (MNRAS). He lost a battle with two much more senior referees, and the paper was rejected. On the advice of Sydney Chapman, he submitted the work to Philosophical Magazine, where it was finally accepted [Dungey, 1953].
In 1950, Jim became a postdoctoral fellow in Sydney working with Giovanelli. He loved Australia, and although he completed his Ph.D. defense remotely from there and the subsequent battle with MNRAS occupied him, he did some interesting new work.
For example, with R. E. Loughhead, he wrote a paper on twisted magnetic fields in astrophysical plasmas [Dungey and Loughhead, 1954], effectively deriving the Kruskal-Shafranov criterion for what is now known as the kink instability for fusion plasmas some years before the secret work of Vitaly Shafranov in the Soviet Union and Martin Kruskal in the United States was finally published in the open literature. Jim always delighted in recalling his astonishment at receiving preprint requests from obscure addresses around the world.
Revelations About the Magnetosphere
Jim then moved to Pennsylvania State University’s (Penn State) Ionosphere Research Laboratory in 1953. In 1954, while at Penn State, Jim wrote one of the great papers of his career, an unpublished report with the shorthand title of “Electrodynamics of the Outer Atmosphere.” In the paper, he discussed a number of basic magnetospheric phenomena—the ideas that standing Alfvén waves would form along field lines and that the outer magnetospheric boundary would be subject to Kelvin-Helmholtz instability—as well as how magnetohydrodynamic waves would interact with the ionosphere, 5 years before the magnetosphere was even formally identified!
The paper was circulated hand to hand among elite researchers during the 1960s and 1970s. Why this paper was not published at the time is not clear. It did form a National Science Foundation contract report and was for some years available from Penn State. Over the next decade, as the International Geophysical Year took place and the space age began, more and more became clear about the existence of the magnetosphere, and he published, in separate places, much of the 1954 report.
Although Jim retained a visiting position at Penn State well into the 1960s, he returned to Cambridge as an ICI Fellow in 1957. There he wrote a wonderfully dense monograph, Cosmic Electrodynamics, for Cambridge University Press [Dungey, 1958], which he once described to me as an exercise in “writing down everything I knew.” It is long out of print but well worth reading still.
In January 1961, Physical Review Letters published his now seminal paper on the reconnection model of the magnetosphere [Dungey, 1961]. Although the basic ideas of the paper drew from Jim’s Ph.D. thesis and he refined his theories while at Penn State, it wasn’t until he was sitting in a café in Paris watching the motion his coffee made as he stirred it that he had the final insight needed to complete his research. The pattern milk made as it was stirred into the coffee reminded him of the storm time ionospheric electrical current system. It was a eureka moment. Suddenly, he realized that Earth’s polar magnetic field must be stirring the ionosphere, and it must be because the field connected directly to the solar field, as his thesis work had described. Jim’s open (or reconnection) magnetospheric model became the foundation of modern understanding of solar terrestrial coupling.
Jim’s conclusion, however, was slow to gain wide acceptance. This was despite the fact that by 1966 Don Fairfield, one of Jim’s Penn State students, had produced evidence that a southward interplanetary field (favoring magnetic reconnection between terrestrial and solar fields) controlled ionospheric magnetic disturbances [Fairfield and Cahill, 1966]. In 1970, Aubry et al.  showed the magnetopause erosion uniquely predicted by Jim’s model. Even so, it was only with the direct measurement of plasma acceleration consistent with magnetic reconnection at the magnetopause [Paschmann et al., 1979] that doubts dissolved.
Following Cambridge, Jim took a faculty position at Kings College in Newcastle (now Newcastle University), and then, because of his increasing reputation for knowledge of Earth’s radiation environment, he was appointed to the U.K. Atomic Weapons Research Establishment in Aldermaston. In 1965, he settled at Imperial College in London, where he remained for nearly 20 years until his retirement in 1984.
The 1961 paper’s massive influence can often distract attention from the results of the other seeds he sowed. He was a theorist, but following the data explosion of the 1957–1958 International Geophysical Year and as the space age developed and in situ measurements from space were obtained, Jim reveled in developing theory in the late 1950s and the 1960s inspired by the emerging new information on what is now called geospace. His fascination with the collision-free plasmas of geospace lay in nature’s departures from expectations derived from classical electromagnetism or the theory of gases. Stimulated very low frequency emission intrigued him immensely, as did auroral currents and acceleration—and, always, collision-free reconnection.
With his U.S. colleagues, he used the Liouville theorem to show that the radiation belts had an external origin. He developed theories of radiation belt stability using whistler mode waves that were the precursor of the now standard Kennel-Petschek model, but he pushed the ideas into a different frequency domain to suggest that bounce-drift resonance with magnetohydrodynamic waves could mediate radial diffusion of the ring current.
In 1966, he proposed a four-spacecraft Tetrahedral Observatory Probe System to the European Space Research Organisation (the predecessor of the European Space Agency (ESA)). His idea finally came to fruition in 2000, when ESA launched the four Cluster spacecraft. Determination of the detailed structure of large-scale currents, Kelvin-Helmholtz boundary waves, the auroral acceleration region, the dayside and nightside reconnection regions, and the bow shock became possible, just as he had envisaged.
An Eccentric Visionary
Few people’s reputations grow as much as Jim’s did after retirement. He was honored postretirement with the Fleming Medal from the American Geophysical Union; honorary membership from the European Geophysical Society, its highest honor; and a Gold Medal from the Royal Astronomical Society (RAS) of London, which recently established an annual James Dungey Lecture.
Jim was a widely respected man but definitely an eccentric. He left his mark on all those who worked closely with him, but they had to learn his way of thinking, and it could be hard. His communication could be telegraphic in the extreme, as is evidenced by the shortness of his papers and his 1958 book. Moreover, when working with him, his quick physical intuition could leave one floundering behind. It is sometimes said he did not suffer fools, and certainly, he could unintentionally offend those who could not follow his arguments. Nonetheless, he was a kind man, and I think that it is truer to say that he tended to say it as he saw it.
Recent detective work by Peter Cargill in the archives of RAS has revealed the names of the two referees who long ago rejected Jim’s Ph.D. thesis for publication in MNRAS. Ironically for me, one of them was my undergraduate tutor, who, a decade later, recommended me to Jim as a Ph.D. student. I have always been grateful for that unlikely recommendation.
Although it was hard work to keep up with him, Jim had an endless capacity to surprise. He was a great mentor and became a good friend.