I am still attempting to build a Farnsworth-Hirsch Fusor however due to the nature of the device (low pressures, high voltages, radiation, etc) I am postponing the project until I can have a clean dedicated space to work on it. I am currently working on getting a workshop to build larger and more precarious projects. My notes on the project will still remain online.
For this project, I am attempting to build a Farnsworth-Hirsch Fusor to demonstrate the concept of fusion. This page details my experiments and research. Here is a very short introduction to fusors.
The uses of such a device are numbered, Farnsworth-Hirsch Fusors can be used to demonstrate fusion principles and as a neutrino source. However, the neutrinos are not produced in a confined beam and so it further limits its uses.
Fusor Research and Resources
Information
A lot of information can be found at fusor.net, a community of citizen scientists with the common goal of building fusion reactors. I found a lot of useful information on their forums as well as in their Fusion Primer.
Materials
Fusor build materials can be hard to find primarily due to the fact that they need to be vacuum rated.
Vacuum Vessels
I have recently discovered that propane tanks are vacuum rated, in fact in order to refill a propane tank it has to be evacuated of air. Propane tanks have to be recertified every few years to continue to be refilled. You probably can find brand new unfilled propane tanks at your local hardware store that with a few fittings properly welded to them can become a sturdy and useful vacuum vessel. An empty Bernzomatic propane tank currently runs $45 at my local Lowe’s as of Oct 2021. You will likely have to purchase high vacuum fittings and either weld them yourself or pay to get them welded on. I am unsure at the moment what type of welding is best for maintaining a vacuum or what is best for attaching the two pieces of metal.
Vacuum Pumps
The vacuum pump is one of the most expensive pieces of equipment that you have to get to build a fusor. I found this thread helpful in finding a quality and relatively cheap vacuum pump. From what I found the best pumps are rotary vane HVAC pumps, on the cheapest they can go for $350 and get down to ~25 microns or lower. If you don’t need something as powerful you can easily get a cheaper pump from Home Depot for half the price or lower. This Stark pump from Home Depot can go down to 5Pa or about 40 Microns. One of the most recommended pumps was the Yellowjacket Bullet which can get down to ~25 Microns or lower. A local HVAC store will probably have this or other brands, when using HVAC pumps remember that you will have to put a vacuum connector on it yourself. Here is a great forum post about proper micron levels.
Some other useful resources: Vacuum pressure converter, Microns of Mercury to Pascals, Used Mechanical Pumps Thread, Cheap Harbor Freight Vacuum Pump, Erik Burrows Farnsworth Fusor Project, Stark Vacuum Pump Data