As many of my readers know, I have become obsessed with the Bussard Fusion Reactor.

There is a bit of amateur scientist in me so I've been on the look out for general directions for making a fusion reactor in a garage or basement. So far 18 amateurs have replicated this experiment.

You could be next. Total cost if everything is bought new should be under $2,000. If you are a good scrounger $500 might do.

Photo at left: Simple demonstration device, built by Worcester Polytechnic Institute sophomore Joshua Resnick as an extracurricular project, sets up a high voltage between two sets of spherical electrodes made from joined metal rings. A transparent bell jar allows the assembly to be placed under low pressure without obscuring the view of the glowing plasma when the device is energized.

The amazing thing about such a device is how amazinly simple it is. There is a fair amount of support equipment required - high voltage generators, vacuum pumps, gas supply regulators, etc. , but the reactor itself is just some grid wires and a vacuum chamber.

Now for the more technical details. Richard Hull[pdf] of Tesla Coil Builders of Richmond, 7103 Hermitage Rd., Richmond, VA 23228, has done an excellent job of explaing the how tos. Microns an torrs refer to levels of vacuum.

The "fusor" can work in several modes based on the materials used, the gas included in the device, and the pressure of the gas. Experimental possibilities are endless and the device itself is interesting to watch. At its low end of operational performance (above 1000 microns) it is working as a conventional glow discharge device but is still more interesting than a plasma globe. Near the top end of its operational performance curve it can produce neutrons through the D-D reaction. This performance curve is still not well defined! The large number of variables make for a great research opportunity.

Nothing is particularly critical in the fusor's physical construction regardless of mode of operation. A good scrounger with a modest vacuum system that can go to 10 microns should be able to assemble the entire device for under $50.00. Buying every thing new except for the vacuum system might drive the cost to $300.00. With a high vacuum system (10-6 Torr), bell jar or stainless steel chamber, and about $400.00 you can be producing neutrons.

One modification I would suggest is dividing the bleeder resistor into two strings each with an LED in series (at the ground end) as indicators of high voltage. Use the highest efficiency LEDs you can get so even relatively low voltages can be seen. In addition I would add a third divider for exact voltage measurement. That divider should be designed so that it shows 2.0 volts for a 20 KV output. Current through that divider should be on the order of 100 uA for 20 KV output. As in all high voltage work the low voltage part of the divider should consist of two parallel resistors so that a malfunction of one does not leave the low end of the divider disconnected.

All the wiring should be done with solid core spark plug wire. All connections well soldered and covered with glyptol to prevent corona discharge.

Nice resource page by Richard Hull.

A good overview with some construction details and safety precautions by Tom Ligon [pdf].

High Voltage Tips

Overall Construction Tips

If any one in the local area needs help I'd be glad to lend a hand. If you are a distance away e-mail will work. Address on my sidebar at Power and Control where this is also cross posted.