Jon Rosenstiel's Fusor: This fusor currently holds the amateur record with a fusion output of 10⁷ ( "ten to the seven" or "10 million") fusion reactions per second

People usually cringe when I mention the words "amateur" and "fusion" in the same sentence, so allow me to explain. As I mentioned in the "Fusion Methods" section, Inertial Electrostatic Confinement is a fairly simple method used to obtain fusion reactions. Invented in the late 50's by Philo T. Farnsworth (inventor of the television as we know it today), the "fusor" (as it is sometimes called) uses ordinary vacuum-tube technologies to accelerate and collide nuclei of fusible atoms. Farnsworth's original fusors were rather complex, but the concept is very simple, and can be adapted to your heart's desire. I will say it again, THIS IS NOT COLD FUSION!!! It is very hot fusion, requiring temperatures of over 200 million degrees! To see why we can do this without destroying the machine, reread this section. Fusors are currently marketed as commercial neutron sources, and used for research in university labs. The idea is not based upon fringe science or new and untested theories. It, along with every other fusion reactor on earth, currently does not break even and produce power!

Philo T. Farnsworth: Inventor of the modern Television and the tabletop fusion reactor

Imagine, if you will, a small geodesic grid, about the size of a golf ball. Now, place that grid at the center of a volleyball-sized metal sphere. Then, charge the inner grid up to a very high negative potential, say -25,000 volts. Leave the "outer grid" at ground potential. It is still positively charged with respect to the inner grid.

Introduce some fusion fuel to the system in the form of a gas, like Deuterium and allow it to become ionized. The Deuterium nuclei are positively charged, so they get attracted to the negatively charged inner grid. Since the grid is mostly hollow, the nuclei miss the geodesic wires and collide with each other at the center of the inner grid. In many of these collisions, the nuclei will get close enough to each other that they will overcome their mutual repulsion (like charges repel) and fuse together. That's all there is to it!

A more detailed description, written by Tom Ligon, can be found here 

The fusor concept: Beams of ions accelerate inward, miss the inner grid, and collide at the center of it.

"It can't be that easy! Why are we spending billions of dollars to do fusion when it can be done for only a few hundred?" I get comments like that all the time. It really is that easy to accelerate nuclei at each other to make them fuse. What's hard is making useful power from fusion reactions. Nobody has managed to do that yet. However, I can't just tell you that fusion can be done on the kitchen table and expect you to believe me. How do we prove that fusion is occurring?

For that, let us recall what the fusion reactions are. Since we are fusing Deuterium nuclei, we are concerned with the following two reactions:

1. D + D → T(1.01 MeV) + p(3.02 MeV)

2. D + D → He3(0.82 MeV) + n(2.45 MeV)

Both of these reactions occur with 50% probability.

Note what the products of each reaction are. We have Tritium, Protons, Helium-3 nuclei, and neutrons being produced. So if we can detect any of these reaction products, we can prove that fusion is taking place. Most amateurs, including myself, have successfully detected the neutrons produced in the fusion reactions using commonly available neutron detectors.

These neutrons are fast neutrons, with a kinetic energy of 2.45 MeV. Neutrons of this energy are produced only in fusion reactions. There are other reactions between Deuterium nuclei that produce neutrons, but they only occur at extremely high energies such as those found in cyclotrons or linear accelerators. The neutrons produced in these non-fusion reactions can also have a whole spectrum of energies. Since fusion only makes fast neutrons, and since we are only detecting those fast neutrons and nothing else, we are only doing fusion reactions.

Researchers at the University of Wisconsin have also detected the high energy protons released in the other reaction listed above. In fact, these protons are being used for the creation of medical radioisotopes!

The residual Helium-3 and Tritium gases can be detected using what is known as a "Residual Gas Analyzer." This is a miniature mass spectrometer that analyzes the makeup of gases in a vacuum chamber. Some amateurs using these devices have noted a significant increase in the levels of these gases after long runs with the fusor.

The evidence is there. Fusion can be, and has been done on the tabletop. It has been verified by 10 or more universities, by the original inventors, and by 15 or more amateurs around the world. Yes, it is that easy.

Click here to see how we measure fusion, and what this means in terms of "breakeven"

The Ludlum 12-4: A typical neutron detector that one would use to detect fusion reactions

Carl Willis taking neutron measurements at Richard Hull's Fusor