Building a fusor is not a simple little thing you can do over the weekend. It can take months, or even years of your time. It is unlikely that you will have all the skills you need to do it at first. Fortunately, it is very easy to learn as you go, as I did. After all, "Research is what I'm doing when I don't know what I'm doing!"

Some of the things you will learn and skills you will master include:

• Metalworking
• TIG welding
• High Power electronics
• Radiation and health physics
• Radiation metrology
• Handling of high pressure gases
• Engineering and use of high vacuum systems
• Nuclear Physics
• Plasma Physics
• Electrical engineering
• History of fusion
• Properties of the chemical elements
• Buying and selling on the internet

A beautiful amateur fusor made by Joe Zambelli

Gerardo Meiro's novel inner grid design

Richard Hull with his "Fusor IV"

These are some of the most frequently asked questions by newbies to the field of IEC fusion. Quite frankly, there is no definitive answer to either of them. What you need depends upon several factors, and the cost depends upon what you can get on the surplus market, what you already have, and how much you are willing to spend.

An experienced amateur scientist, with good scrounging skills, can probably spend under $200, depending on what equipment he or she already has. An inexperienced newbie, who wants fusion RIGHT NOW, can spend $8000 or more, and then realize that he could have saved a lot of money in retrospect. Most people fall somewhere in between these two extremes.

To make a fusor, you really only need a few things:

• A vacuum chamber; preferably made of stainless steel for Fusion models, Pyrex is OK for non-fusion devices.
• A vacuum pump capable of reaching pressures of 10^-3 Torr (1 micron Hg) or deeper. A 2-stage mechanical pump is usually good enough. Lower pressures require oil diffusion or turbomolecular pumps in addition to a mechanical pump.
• A high voltage power supply; this must be a direct current, negatively biased (i.e. positive grounded) power supply. For fusion models, this supply should be rated at 20,000 volts (minimum) and 20 milliamps. A surplus x-ray transformer, with the proper DC rectification, is typically the best option. For non-fusion demo models, you can use a neon sign transformer. If you have the cash, Glassman High Voltage sells amazing power supplies that are perfect for fusor work. I found one on ebay for a tenth of the normal price.
• Deuterium gas; This gas is fairly easy to get in small 50 liter lecture bottles for about $250. It has no special regulations and is non-radioactive. You will need a regulator to go with the bottle in order to lower the pressure from 1500psi to about 2psi. *Tritium* is not obtainable by the amateur. Tritium requires a site license from the U.S. Nuclear Regulatory Commission, with facilities more secure than most private homes. The Farnsworth team had to submit to weekly medical exams because of its radioactivity. Don't even think about trying to get Tritium. It is dangerous and illegal for the amateur.
• A neutron counter; this is how you quantify your fusion results. A brand new, el cheapo neutron counter costs about $2000. Until recently, fusioneers had to wait around on ebay until a neutron counter rolled by. Now, there is a new technology out there know as a "Bubble Neutron Dosimeter." These are small tubes filled with a certain liquid, sensitive only to fast neutrons from fusion. They cost about $100 and have a shelf life of about a year.  

Here is an abbreviated parts list of my Fusor, with approximate prices (For a full parts list, go here):

Vacuum pump........................................................................$75 on ebay
20,000 Volt, 50mA power supply...........................................$300 on ebay
Stainless Steel Chamber...........................................................$600 total
Neutron Detector.....................................................................$150 on ebay
50L of Deuterium Fuel..............................................................$245 from Advanced Specialty Gases
Various vacuum components and other peripherals.....................$????
Total.......................................................................................~$1500-1800
 

As you can see, it isn't exactly cheap. But you should realize that these parts were acquired over a period of 18 months, and only after researching as to their necessity in the project. It's the little things like valves and fittings that eat out your wallet. High vacuum equipment is also high precision equipment, making it fairly expensive.

Also note that a non-fusion demo model can be made for far less, perhaps $200 if you get lucky on ebay. Either way, both of these figures are well within the reach of dedicated amateurs and students. Remember, "If you can dream it, you can do it!"

As with any nuclear-related project, safety must be taken into consideration. Here are some of the biggest dangers associated with this project:

• High Voltage; the voltages required in ANY kind of fusor are LETHAL! If you accidentally come into contact with the live wire, you will be dead before you even knew you made a mistake! If you get shocked, it my not be your first experience of electrocution, but it will certainly be your last!
• Mechanical Hazards; Poorly made vacuum chambers can implode, sending shards of glass and metal into your face. Welding torches are hot! Machining metal produces razor-sharp metal chips. Always wear eye protection when appropriate and avoid the use of glass in a vacuum system if you plan on going above 5000 volts.
• Radiation; this should be the least of your worries until about 15,000 volts of acceleration potential. At this point, x-rays start to emanate from viewports due to electron and ion bombardment of metals in the chamber. Always use a camera or mirror to peer into the viewport. X-rays can cause burns and lead to cancer. Above 40,000 volts, x-rays will start to come through the stainless steel chamber walls. At this point, you will need to use lead shielding. Neutron radiation is the most dangerous form of radiation known to man, but the fusor does not put out enough of it to be dangerous until about 45,000 volts. It can easily be shielded with water, wax or plastic. You can also minimize your exposure by standing well away from the fusor, or by operating it for only 20 minutes per week.