Hey! Today, I'm going to share with you the main component of the design of my fusor. A Hirsch-Meek fusor mainly consists of two components: the Vacuum system and the Circuits. There are some additional parts that can be added -such as a regulated deuterium injecting system or temperature, light and x-ray counters-, but in order to achieve the formation of a plasma sphere, all you need is:
A stable and strong vacuum.
A significant (and by significant i mean in the order of tens of thousands) amount of volts.
Today, we are going talk about the vacuum chamber, and the best ways available to optimize vacuum at different budgets.
Before we start, just a little disclaimer: pay attention when working with vacuums, as the chambers can easily implode. always consult a professional before starting, and keep a safety distance from the chamber when under vacuum!
Vacuum chamber
If you want to build a high-quality fusor, the best option available is a vacuum chamber. I would advice to purchase a metal one, so that you can electrify the chamber itself using it as the outer grid. Another option is a transparent vacuum chamber (made of glass or similar materials) but i don't recommend to use it as it increases the risk of implosion and requires the implementation of a second internal grid.
Figure 0: Vacuum chamber. Source https://www.atlasuhv.com/products/vacuum-chambers/titanium-chambers/
A vacuum chamber is generally the best option, but it has one downside: it's extremely expensive. I couldn't find one at less than $3.000, but if you're willing to spend the money its totally worth it! It's also the safest option, as it's been tested and built for strong vacuums.
2. The "homemade" technique
Within the "fusers" -a nerdy community of people like me- its veery common to build a homemade vacuum chamber. The most popular shape is the cylinder: a metal ring closed on the sides with a transparent material. There are plenty of tutorials on the web on how to build one, and in case you decide to go for this shape, here is some useful youtube channels where the process is very well explained: Plasma channel: https://www.youtube.com/watch?v=VTBZ0VwIgs8 , Will from London: https://www.youtube.com/watch?v=EVOBk-InL00 .
Here is a picture of the beautiful design Will from London (second link above) Came up with. Even though this type of chamber doesn't guarantee the strongest vacuum, its still a reasonably good and cheap solution.
3. Sight Glass technique
This is the technique i used to build the vacuum chamber of my fusor. I think its the best option available as it has a reasonable price ($60-200) and provides a strong vacuum. We use, as a vacuum chamber, a sight glass -that component thats often used in food processing and industries. It's very well sealed and contains both a metal and a transparent component, that allows you to use it as an outer grid.
Figure 1: Sight glass. Source: https://www.steelobrien.com/products/sight-glasses/sight-glass/
Before purchasing a sight glass, note that you will also need to buy two caps and clamps to close it on the sides. The caps will need to be drilled, as we want to connect an electrical source and the vacuum port. Be careful... before purchasing one always verify with the producer what degree of vacuum and heat its designed for... we want to avoid implosions!
Conclusion
There's no "right" or "wrong" way to build your chamber, the important thing is that you carefully evaluate the expenses-to-quality ratio you want your project to be built on, and, most importantly, be safe! Always put something between you and the chamber, wear lab goggles, keep distance and be extremely careful when working with vacuums: if the chamber is damaged, don't use it!