Brian's Fusor Parts List and Construction Tips
This page is intended to aid those who want to build their own fusors. Note that this is not the only way to go, and there are many alternatives to the design proposed here. This design is based upon my observations of other people's Fusors, the Hirsch-Meeks patent, and my own personal preferences. It is in no way flawless, and there are several things that I would change in a future fusor.
I expect that an intelligent person will see the flaws in my design, and correct them in his or her own fusor. You are responsible for your actions if you decide to copy my design. I encourage people to think for themselves, rather than copy this parts list when building a fusor. This is just here to give you a rough idea on what needs to be done.
Granted, there is no limit to what you can do when designing a fusor, and diagrams/schematics can be quite useful to somebody new to the field who wants a proven design that works. I provide you with more information than most fusor sites out there, so my site is probably as close as you'll get to finding "plans" for a fusor. You can (I'm tempted to say must) also go to Fusor.net and look through the forums for ideas and information.
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Cost of a new Fusor?
If you choose to buy all of these parts new, the total cost for a brand new
fusor will be about $11,975! This assumes a $1900 vacuum pump, a $5300 Glassman
power supply and a $2100 Ludlum neutron counter. I also assumed a fabrication
cost of $400.
You can see why nearly everybody who has made a fusor has used surplus or
homemade items, as this can cut the cost by 80% or more! My fusor--to date--has
cost about $3500. The total cost to actually get the thing up and running was
about half of that. What you save in money, you wind up spending in time and
effort. You have to figure out where to draw the line between buying new parts
and salvaging/fabricating your own.
Vacuum System:
Vacuum parts are available from many of the suppliers listed in the Links section. Click the thumbnail to see parts labeled on the chamber and cart.
304 Stainless Steel hemisphere X2
8" (outer diameter) non-rotatable conflat flanges with 6" bore and weld lip X2
2.75" Conflat half nipple X3
1.33" Conflat Half Nipple
2.75" Conflat Viewport
0.125" Swagelock "tubing to weld systems" fitting
2-stage rotary vacuum pump, capable of pressures of 1 micron Hg or lower
Kurt J. Lesker "Micromaze" foreline trap (advanced users only)
Quick flange 25 (QF25/KF25) half nipple
QF25 right angle valve 1 or 2, depending on whether or not you have a Micromaze
Vacuum hose (if necessary)
2.75" Conflat high voltage feedthrough insulator
Any necessary Conflat blank flanges for unused ports
The whole chamber weighs roughly 20-35 lbs, fully assembled.
Electrical System:
Glassman WX series power supply, 20,000 volts and 50 mA (higher voltage is preferable)
High voltage cable, rated for 60kV
8' copper plated ground rod, driven into the earth
Appropriate electrical wall sockets, rated for 20 amps or better; I've managed to run the whole setup (pumps and other peripherals included) at full power (>1kW) using only a common 120 volt household socket. If you could run a toaster or microwave off a particular outlet, you could probably run a fusor off it as well. More advanced systems may require a 220 volt dryer-type socket.
Deuterium Gas Handling System:
Click on the thumbnail to see the placement of the parts in the system
Pressure regulator, 5000 PSI on input side, 0-60 PSI on output side
50cc gas sample cylinder for use as a reservoir
Shutoff valves to isolate reservoir
Shutoff needle valve
Fine metering needle valve
Ultra-fine metering needle valve
0.125" stainless steel tubing
Lecture bottle with 50L STP of Deuterium Gas
Compatible CGA fittings that match the gas cylinder and regulator (i.e. CGA 350 or 180)
Metrology/Safety Equipment
Simple Geiger counter for detecting x-ray leaks
Neutron detector of some sort (BF3, He3, bubble dosimeter)
Digital event counter for logging gross neutron counts
Ionization chamber detector for quantifying x-ray levels
TV monitor and camera for peering into viewport
Lead shielding for viewport area
Construction Tips
Click the first thumbnail to see a simple drawing showing a general assembly procedure. The second shows the welds made on the inside surface.
Use only TIG welding techniques! Other types of welding can crack, trap gases, or make a mess of your chamber. TIG welding with stainless steel is simple and hard to mess up.
Tack weld first! Make a small tack weld every 90 degrees around the circle to hold the part or flange in place. This will also prevent warping of the metal.
Don't make the holes too big! When machining the holes for the ports and fittings, make them slightly small at first. It should be a very tight fit, and you should have to use a firm twisting motion to get the fitting into the hole. Remember, you can widen a hole that is too small, but you can't shrink one that is too big.
Be careful not to damage the Conflat flanges. The mating surfaces of these flanges have a precision made knife-edge to them. Any nick or scratch in the Conflat knife edge will cause it to fail and your vacuum will leak!
The large Conflat flange that the hemisphere seats into has a 0.5" wide weld lip that the hemisphere will rest on. Unless you remove that much material from the bottom of the hemisphere, your chamber will be egg-shaped. This won't affect fusion results, but a perfectly spherical chamber looks a bit nicer.
Plan out your port arrangements before you assemble your chamber! Otherwise, you may have ports that are to close to each other and it may be impossible to tighten the bolts later on because you wont have space for a wrench.