History of Focus Fusion

1964—The Plasma Focus is invented simultaneously in the US and the USSR by Mather and Fillipov.

Late 60’s to early 70’s—Winston Bostick and Victorio Nardi at Stevens Institute of Technology, Hoboken, NJ, develop the basic theory of the plasma focus, showing that energy is concentrated into tiny hot-spots or plasmoids, contained by enormous magnetic fields. Their discoveries become highly controversial, as other researchers insist that the energy is far more diffuse and ignore mounting experimental evidence from Stevens and other groups. During this same period US fusion efforts become concentrated almost exclusively on the tokamak. However, the number of groups around the world doing focus work grows to a few dozen. Funding for each group remains very limited. Work is also hampered by lack of quantitative version of Bostick-Nardi theory.

1986—Eric Lerner of Lawrenceville Plasma Physics publishes first quantitative theory of dense plasma focus (DPF) and plasmoid, using theory to successfully model quasars. The theory is based on Bostick-Nardi model, and was developed with advice from Nardi. In the next few years this theory is extended to predict plasma focus performance for various fuels, showing that improved performance is expected with hydrogen-boron fuels.

Late 80’s to early 90’s—End of Cold war and decrease in general funding of physical science leads to drastic cuts in focus fusion, with about half of the groups ceasing to function and many others redirecting research to x-ray lithographic applications. Fusion funding is cut and concentrated ever more narrowly on Tokamaks.

1994—Experiments performed at University of Illinois on small plasma focus confirm predictions of Lerner’s theory, including five-fold enhancement of output with smaller electrodes.

2001—Experiments at Texas A &M university confirm predictions from Lerner theory that energies above 100 keV (equivalent to 1.1 billion degrees) can be achieved with plasma focus.

2002—New theoretical calculations indicate that strong magnetic field in DPF can suppress heating of electrons and thus x-ray cooling of plasma. This makes achieving net energy easier and implies that very compact electrodes are desirable.

Progress with the DPF has been impeded mainly by a lack of good quantitative theoretical models. There are too many parameters in the DPF to allow progress on a purely empirical basis—there are the anode and cathode radii, electrode length, shape of the anode and especially anode tip, length of insulator, charging voltage, fill pressure, fill gas, and so on. Without a good theory, DPF research is like wandering in a six-dimensional desert looking for small oases. But many groups researching the DPF do not have a clear idea of the importance of the plasmoids, attributing much of the DPF’s radiation to a broader pinch region. Of those groups that do understood the plasmoids’ importance, only one, other than our own, use the basic theoretical model of plasmoid formation and decay developed by Bostick and Nardi[4].

However, even that model, without LPP’s own additional work, does not yield quantified predictions for different gases. This means that there has been, apart from our own work, no way of predicting in advance the size, density, magnetic field and ion and electron energies of the plasmoids in the DPF, given initial conditions.

Equally important, most groups, handicapped in part by funding limitations, have not had available the diagnostic equipment needed to provide simultaneously the high spatial and time resolution needed to study the plasmoids. This situation has been complicated by the lack of ability of almost all groups to distinguish instrumentally between x-ray emissions from the plasmoids and from the collision of the electron beams with the anode, which has led to a great deal of confusion in the field.

The result of these barriers has been to prevent any group, other than LPP and those working with us, from demonstrating the achievement of high electron temperatures, and has prevented any group at all from combining high temperatures and efficiencies. Our own work thus far has been hindered by our lack of funding for the development of a facility that allow free adjustment of the experimental parameters. At Texas A&M, the experimental facility did not allow for the modification of the anode radius, which in turn precluded achieving high efficiency. As well, we have not yet had funding to develop the simulation we need to help guide future work.

In 1986, Lerner outlined a new theory of quasars that did not require black holes, describing quasars as a magnetic self-compression process similar to that occurring in the plasma focus. In effect, the plasmoid in the plasma focus is a tiny scale model of a quasar. In the course of this work, Lerner developed a quantitative theoretical model of the plasma focus which was consistent with all then-available data. The next year, he showed, in proposals to the Department of Energy, how this new theory indicated that the plasma focus could burn advanced fuels, especially hydrogen-boron, and developed the theoretical framework for describing the effect of differing filling gases on the plasma focus.

While the Department of Energy declined to fund this work, Lawrenceville Plasma Physics obtained small grants from NASA’s Jet Propulsion Laboratory for space applications. In 1994, Lerner and colleagues at the University of Illinois successfully tested some of the predictions of his theory using a small plasma focus device there.

In 2001, Lerner and colleagues at Texas A&M University successfully achieved ion and electron energies equivalent to two billion degrees K, sufficient to fuse hydrogen-boron fuel. [Click here for details].

Two years later Lerner demonstrated that the high magnetic fields that can be produced in the plasma focus will greatly reduce the cooling of the plasma by x-rays from the electrons, and thus make achieving net energy production easier.