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January 05, 2009

Focus fusion $1.2 million two year nuclear fusion project


Lawrenceville Plasma Physics, the group looking to develop dense plasma focus fusion (focus fusion), has provided details of $1.2 million in funding and the project plan.

This approach to nuclear fusion has been covered before on this site

Lawrenceville Plasma Physics Inc., a small research and development company based in West Orange, NJ, has announced the initiation of a two-year-long experimental project to test the scientific feasibility of Focus Fusion, controlled nuclear fusion using the dense plasma focus (DPF) device and hydrogen-boron fuel. Hydrogen-boron fuel produces almost no neutrons and allows the direct conversion of energy into electricity. The goals of the experiment are first, to confirm the achievement the high temperatures first observed in previous experiments at Texas A&M University; second, to greatly increase the efficiency of energy transfer into the tiny plasmoid where the fusion reactions take place; third, to achieve the high magnetic fields needed for the quantum magnetic field effect which will reduce cooling of the plasma by X-ray emission; and finally, to use hydrogen-boron fuel to demonstrate greater fusion energy production than energy fed into the plasma (positive net energy production).

The experiment will be carried out in an experimental facility in New Jersey using a newly-built dense plasma focus device capable of reaching peak currents of more than 2 MA. This will be the most powerful DPF in North America and the second most powerful in the world. For the millionth of the second that the DPF will be operating during each pulse, its capacitor bank will be supplying about one third as much electricity as all electric generators in the United States.







A small team of three plasma physicists will perform the experiments: Eric Lerner, President of LPP; Dr. XinPei Lu and Dr. Krupakar Murali Subramanian. Mr. Lerner has been involved in the development of Focus Fusion for over 20 years. Dr. Lu is currently Professor of Physics at HuaZhong Univ. of Sci. & Tech., Wuhan, China, where he received his PhD in 2001. He has been working in the field of pulsed plasmas for over 14 years and is the inventor of an atmospheric-pressure cold plasma jet. Dr. Subramanian is currently Senior Research Scientist, AtmoPla Dept., and BTU International Inc., in N. Billerica, Massachusetts. He worked for five years on the advanced-fuel Inertial Electrostatic Confinement device at the University of Wisconsin, Madison, where he received his PhD in 2004 and where he invented new plasma diagnostic instruments.

To help in the design of the capacitor bank, LPP has hired a leading expert in DPF design and experiment, Dr. John Thompson. Dr. Thompson has worked for over twenty years with Maxwell Laboratories and Alameda Applied Sciences Corporation to develop pulsed power devices, including DPFs and diamond switches.

The $1.2 million for the project has been provided by a $500,000 investment from The Abell Foundation, Inc, of Baltimore, Maryland, and by additional investments from a small number of individuals.

The basic technology of LPP’s approach is covered by a patent application, which was allowed in full by the US Patent Office in November. LPP expects the patent to be issued shortly.


FURTHER READING
Technical details

The dense plasma focus device consists of two cylindrical copper or beryllium electrodes nested inside each other. The outer electrode is generally no more than 6-7 inches in diameter and a foot long. The electrodes are enclosed in a vacuum chamber with a low pressure gas filling the space between them.

A pulse of electricity from a capacitor bank (an energy storage device) is discharged across the electrodes. For a few millionths of a second, an intense current flows from the outer to the inner electrode through the gas. This current starts to heat the gas and creates an intense magnetic field. Guided by its own magnetic field, the current forms itself into a thin sheath of tiny filaments; little whirlwinds of hot, electrically-conducting gas called plasma. A picture of these plasma filaments is shown below along with a schematic drawing.

This sheath travels to the end of the inner electrode where the magnetic fields produced by the currents pinch and twist the plasma into a tiny, dense ball only a few thousandths of an inch across called a plasmoid. All of this happens without being guided by external magnets.

The magnetic fields very quickly collapse, and these changing magnetic fields induce an electric field which causes a beam of electrons to flow in one direction and a beam of ions (atoms that have lost electrons) in the other. The electron beam heats the plasmoid to extremely high temperatures, the equivalent of billions of degrees C (particles energies of 100 keV or more).

The collisions of the electrons with the ions generate a short pulse of highly-intense X-rays. If the device is being used to generate X-rays for our X-ray source project, conditions such as electrode sizes and shapes and gas fill pressure can be used to maximize X-ray output.

If the device is being used to produce fusion energy, other conditions can minimize X-ray production, which cools the plasma. Instead, energy can be transferred from the electrons to the ions using the magnetic field effect. Collisions of the ions with each other cause fusion reactions, which add more energy to the plasmoid. So in the end, the ion beam contain more energy than was input by the original electric current. (The energy of the electron beam is dissipated inside the plasmoid to heat it.) This happens even though the plasmoid only lasts 10 ns (billionths of a second) or so, because of the very high density in the plasmoid, which is close to solid density, makes collisions very likely and they occur extremely rapidly.

The ion beam of charged particles is directed into a decelerator which acts like a particle accelerator in reverse. Instead of using electricity to accelerate charged particles, they decelerate charged particles and generate electricity. Some of this electricity is recycled to power the next fusion pulse while the excess (net) energy is the electricity produced by the fusion power plant. Some of the X-ray energy produced by the plasmoid can also be directly converted to electricity through the photoelectric effect (like solar panels).

The DPF has been in existence since 1964, and many experimental groups around the world have worked with it. LPP’s unique theoretical approach, however, is the only one that has been able to fully explain how the DPF works, and thus exploit its full capabilities.


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