Lawrenceville Plasma Physics has been developing an extremely low-cost approach to fusion power based on a device called the dense plasma focus (DPF). In contrast to the giant tokamak machines that have been the recipients of most fusion funding, a DPF can fit in a small room. LPP’s final feasibility experiments and planned commercial generators will use hydrogen-boron fuel, which produces no radioactive waste and promises extremely economical clean energy.
The committee of researchers was led by Dr. Robert Hirsch, a former director of fusion research for the US Atomic Energy Commission and the Energy Research and Development Agency. Other members of the committee were Dr. Stephen O. Dean, President of Fusion Power Associates and former director of fusion Magnetic Confinement Systems for the Department of Energy; Professor Gerald L. Kulcinski, Associate Dean for Research, College of Engineering, University of Wisconsin-Madison; and Professor Dennis Papadopoulos, Professor of Physics, University of Maryland. The committee was organized by Dr. Hirsch at the request of Mr. Alvin Samuels, an investor in LPP’s effort, to give an objective assessment of the program. Neither Mr. Samuels nor LPP had any control over the committee’s conclusions.
If the physics issues outlined herein can be satisfactorily resolved, it is conceivable that the DPF concept could be developed into a viable, economic, and environmentally attractive electric power source for not only civilian power but also for military purposes. LPP’s projection of very small (about 5MW) units would be an advantage relative to most other fusion concepts. To date, LPP personnel have not given extensive consideration to the engineering of a DPF power reactor. This is appropriate in the committee’s opinion, because without the successful resolution of existing issues, a DPF reactor will not be possible. Having said that, the committee does not see any fundamental roadblock to power system viability.
The committee’s report pointed to the “innovative thinking and experimental results achieved thus far by Mr. (Eric J.) Lerner and his team at LPP.” At the same time, the scientists did not minimize the remaining work that still needs to be done to experimentally validate the predictions of LPP’s theory of DPF functioning and lay the foundation for commercial fusion generators. Commenting on the report, LPP’s President and Chief Scientist Lerner said, “We agree with the review committee that several of our predictions still need to be proved in the laboratory, which is what we intend to do in the near future.”
The LPP team has stated that, given adequate funding, they can demonstrate in a year or two the scientific feasibility of fusion energy with the DPF and hydrogen-boron fuel, a combination the team calls “Focus Fusion.” They expect that a working prototype generator can then be developed in a few years more.
The review committee broadly supported that short-term timeframe, concluding: “While a number of near-term physics issues remain to be resolved, it is likely that with adequate financial support these matters could be addressed in a relatively short period of time, e.g. a few years.” If these issues are addressed, “the committee does not see any fundamental roadblock to power system viability.” In other words, a functioning, economical and clean new source of energy may soon become reality.
Highlights of the LPP”s program, based on a theoretical model developed by Mr. Lerner are as follows:
1. The concept should operate more effectively with heavier elements, such as boron.
2. Scaling to effective operation is towards smaller sizes. 3. The so-called Quantum Magnetic Field effect, postulated in astrophysical plasmas but not verified in laboratory experiments, will reduce energy transfer from hot ions to electrons thereby preventing catastrophic energy loss due to bremsstrahlung emission by hot electrons.
4. Lerner’s theoretical model predicts that reduction of bremsstrahlung loss and reabsorption of synchrotron radiation by the dense and opaque plasma focus could allow the pB11 DPF pinch to reach ignition.
5. After the pinch disassembles, Lerner believes that plasma ions will be exhausted along the axis of the device, carrying roughly two-thirds of the plasma energy, allowing efficient direct energy conversion to electric power.
6. Based on his theoretical model, a weak axial magnetic field might enhance the beneficial formation of the pinch plasma.
The committee’s views on these points are as follows:
1. DPF operates more effectively with heavier elements. This prediction from the model remains to be verified. In the near future LPP has a credible plan to test this theory using Nitrogen as a stand-in for Boron. This appears possible, and, if proven, would be a distinctive characteristic of the DPF.
2. DPF wants to scale to smaller sizes. This prediction of the model also needs experimental validation. This appears possible, and, if demonstrated, is a positive, distinctive characteristic of the DPF. Smaller size scaling would be unique among fusion concepts and would mean that program development might proceed rapidly. On the other hand, in a power producing device, small size might lead to difficult device cooling, an issue that cannot be evaluated at this time.
3. The Quantum Magnetic Field Effect will keep electron temperatures lower than the ion temperatures. This effect has never been seen in laboratory experiments. Its demonstration represents a major challenge since it requires much higher densities and much higher self-generated magnetic fields. Lower electron temperatures are essential for this or any pB11 concept, because electron temperatures near ion temperatures would result in radiation losses that would prohibit net power production.
4. Ignition with pB11 may be possible. While conceivable, ignition in pB11 has to our knowledge not been previously considered possible in other pB11 fusion concepts. If achievable, it would provide a distinct advantage for the DPF pB11 approach to fusion power.
5. Plasma ions will be exhausted along the axis of the device. If true, beam ion exhaust holds considerable potential for direct energy conversion, a distinct advantage, assuming relative engineering simplicity is viable.
6. A weak axial magnetic field may help pinch formation. LPP presented plausible arguments and data to the committee on this proposition. If true, it could represent a means of enhancing operation of a DPF system.
1. Plasma densities in the current experiment: LPP personnel and the committee believe that the plasma densities in the existing DPF experiment are too low by over a factor of 10,000 to be practical for a pB11 fusion power system. Since observed densities at LPP are currently lower by about a factor of 10-100 than in many other DPF experiments, there does not appear to be a fundamental barrier to achieving higher densities than currently observed in the LPP device. LPP personnel believe that the reason for current low plasma densities is the high impurity content of current plasmas and that a change in device electrode material is a potential solution. LPP proposes to fabricate their anode out of tungsten to dramatically reduce impurities and increase plasma densities. This approach seems reasonable to the committee. Densities must be increased even further by demonstrating the effect of using a heavier element (like the Nitrogen proposed) and eventually reaching the higher densities required for the quantum magnetic field effect.
2. Impurities in the current experiment: Both LPP and the committee recognize that impurity concentrations must be dramatically reduced.
3. The LPP program: The current LPP program is grossly underfunded and appears to be living hand-to-mouth. In spite of the issues and uncertainties outlined in this report, the committee feels that the promise of the LPP DPF approach to fusion power has considerable merit and that a much higher level of investment is warranted, based on their considerable progress to date. Enhanced support should largely be used for additional experimental and theoretical efforts as well as for additional diagnostics and a larger experimental facility to accommodate additional diagnostics.
4. Developing the DPF to a viable, economic, environmentally attractive fusion power reactor: If the physics issues outlined herein can be satisfactorily resolved, it is conceivable that the DPF concept could be developed into a viable, economic, and environmentally attractive electric power source for not only civilian power but also for military purposes. LPP’s projection of very small (about 5MW) units would be an advantage relative to most other fusion concepts. To date, LPP personnel have not given extensive consideration to the engineering of a DPF power reactor. This is appropriate in the committee’s opinion, because without the successful resolution of existing issues, a DPF reactor will not be possible. Having said that, the committee does not see any fundamental roadblock to power system viability.