Basement fusion reactor

Do you ever wonder what projects your neighbors have going on in their basements? [Will Jack's] neighbors might be surprised to find he’s building a fusion reactor. The first step toward completing a Farsworth-Hirsch Fusor is up and running. The picture above shows heated plasma contained in a magnetic field. Next he just needs to up the voltage and inject some deuterium.

Yeah right! Deuterium, aka heavy water, is extremely rare and very difficult to refine. If you’re not familiar with the substance, you should get your hands on the NOVA episode: Hitler’s Sunken Secrets.

We’re glad to see that [Will Jack] is donning a lead vest for protections.  [Will O'Brien] cautioned us about the stray X-rays these things produce when he covered fusors back in 2007.


  1. k0ldBurn says:

    And I thought I was badass when I rebuilt a broken roomba and got it to run again… This is awesome

  2. Paul Potter says:

    Oh man!

  3. regulatre says:


  4. stevetronics says:

    Deuterium is actually not that uncommon: it it roughly 1:6500 for hydrogen to deuterium atom for atom. That sound like a lot, but when you consider the sheer number of hydrogen atoms on earth, there’s a lot of deuterium around.

  5. Will Jack says:

    Actually, deuterium isn’t that hard to obtain, as it is not radioactive and is sold in lecture bottles for about $150, however tritium (helium 3) is very hard to obtain by an amateur as it is radioactive.

  6. Nwyawka says:

    If this unit is Farnsworth Fusors then there is no magnetic confinement of plasma. Fusors use inertial electrostatic confinement.

  7. Aleksejs says:

    Won’t it end the same way as this:

    ??? :D

  8. Will Jack says:

    Nwyaka- you are correct, this is a farnsworth-hirch type fusor and it does use IEC confinement, tokamak fusors use magnetic confinement, however, the ions in it are accelerated due to the inner grid’s negative electromagnetic charge.

  9. Will Jack says:

    Aleksejes- David Hahn’s plan was to build a “breeder” reactor to create fissionable elements and as result, x-rays poured out of his device. In farnsworth fusors, x- rays usually do not appear until the input voltage reaches about 40 kv, which is far higher than mine, which has an input voltage of about -9500 volts DC (from a 15 kv neon sign transformer, full wave recified)

  10. Brianmanden says:

    Deuterium == Hydrogen 2
    Deuterium != Heavy Water
    Tritium == Hydrogen 3
    Tritium != Helium 3


  11. Digital says:

    Good News everybody, I’ve just invented a new way to kill all of us. now if you’d all stop complaining I’d like to get on with the experiment!

  12. Stu says:

    *checking if its April 1st*

    This is a joke, right?
    People experimenting with radioactive substances and apparatus in their homes!? In neighbourhoods?
    Its downright irresponsible. Oh yeah its great if HE wears a lead vest, how about every other poor sod in his neighborhood, and beyond? Babies and children included? Or have we all forgotten that radioactivity travels clean through 1000 house walls? That renders it more dangerous than an LSD production lab.
    Call the police on the scum, he should be locked away.

  13. Snard says:

    Good news everyone!

  14. Will Jack says:

    @ stu – No dangerous radiation (X-Ray, Neutron, ETC.) is emitted from this device.UV radiation is produced, but the levels are not harmful, plus, I have UV protected contacts.

  15. Will Jack says:

    It is practically a fancy neon light

  16. 24601 says:

    Do a little research Stu. There’s nothing radioactive about a Fusor.

  17. answr42 says:

    Sure he may have a lead vest on to protect against EM radiation, but the real danger comes from the neutrons that are released if he ever gets this reaction running… I would suggest putting the reactor vessel in a deep pool if you value your life.

  18. David says:

    I hope your wearing more than a lead vest!?,2933,299362,00.html

  19. nave.notnilc says:

    err, stop spreading nonsense, as the builder said above, the voltage isn’t high enough to generate any radiation with significant penetrating power.

  20. Will Jack says:

    Sorry for typo in previous comment, I meant hydrogen, not helium

  21. 24601 says:

    Will: Pretty much, but they’re so much prettier than a standard neon, particularly the last image on this page:

  22. nave.notnilc says:

    ugh, this post is going to become a monstrous pile of nonsense and denying nonsense :P

    /me predicts 150+ comments

  23. eDave says:

    D-D fusion reactions have a neutronicity (percent of energy released as neutrons) of 0.66.
    So once this thing is up and cooking deuterium neutron radiation could be more of a problem. But if it’s in a basement, I’d only be worried about anyone actually in the basement.

  24. MS3FGX says:

    As others have said, this is a far cry from a fusion reactor, and is little more than a novelty; though still a very interesting project.

    This device is relatively harmless (certainly, other projects featured on HaD are more likely to kill you than this), any concern about this device is from confusion and misunderstanding of the technology.

    Sadly, it is mindsets like Stu’s that have criminally held back research like this (or anything involving nuclear, for that matter).

  25. 24601 says:

    just have to watch out for the nuclearphobes who have the same reaction as Stu above, and try to have you arrested.

  26. Will Jack says:

    When I start fusing deuterium, it will be remotely controlled. It will also have adequate shielding.

  27. zengar says:

    I just love the continuing “fallout” from the cold war. Everything having to do with atomic power was shrouded with secrecy and miss-information, and as a result you now only need to say the word ‘nuclear’ to make some people’s brains turn off. Have you people ever played with a plasma globe? At this point it’s about the same level of danger.

    People have been building these in basements and garages for years. (not to take away from Will Jack’s achievement, just because people have done it before doesn’t make it any easier or less cool)

  28. anon says:

    what you use that for? toasting some epic bread?

  29. Stu says:

    @24601 @nave.notnilc – NO I will not do my research because I’m not the slightest bit interested in becoming a nuclear fusion scientist, I never claimed that it WOULD generate dangerous radiation, I’m just entitled to be concerned about nutjobs like this guy who could potentially generate dangerous radiation at some point.

    If the levels are likely to be dangerous, then he should go to jail for carrying out dangerous experiments in non-industrial areas. Its clearly non govt-authorised, totally unregulated, possibly under-shielded. Simple.

    It appears we have some closet nuclear technicians on this comments page, it seems. God knows there’s no concensus on these comments pages as to whether its dangerous or not! I can’t tell whether this shit produces radiation but its damned well irresponsible to find out in a neighbourhood!

  30. Stu says:

    @MS3GFX – you are a dick. Simple.

  31. eDave says:

    It should also be noted that though some ionizing radiation is highly penetrating, it still falls off with the square of the distance. It doesn’t have to go far before it falls down to an intensity that is indistinguishable from background radiation.

  32. Will Jack says:

    @ Stu … did you just blatantly ignore everything I just said? Also, the neutron radiation that is emitted for these devices (when fusing) is incredibly small, and is very easily shielded.

  33. jeditalian says:

    good thing its fusion not fission:)

  34. poiso says:


    Best Be trolling, seriously, reading will teach you so much!

    STFU and appreciate when people are smarter then you are…. it’s ok to be scared about what you dont understand, just like when you where amazed at the toaster!

  35. momotarosan says:

    counting down to Dec 1012, 10,9,8,7….

  36. baobrien says:

    I know someone that is trying to build a ‘fusion reactor’. These projects are all very interesting.

  37. nick says:

    @ Stu,

    you need to gtfo. take your crazy elsewhere.

  38. lee says:

    Without any heavy hydrogens (ie extra neutrons) he is only doing what is called ion multipacting of whatever charged particles remain inside the presumed vacuum chamber.
    when he back-fills the vacuum with deuterium or tritium hopefully accelerating some of them into one another fast enough for fusion, he will be producing neutrons which is a radioactive byproduct. This is a pretty difficult task as the vacuum has to be strong, but its possible. if he gets arcing between the charge grids, he can also risk making some nasty x-rays, so good call with the lead vest. For the neutrons i heard borax, which apparently contains boron, is a good collector of excess neutrons.

  39. CalcProgrammer1 says:


    Your mindset is why scientists are leaving the USA. People can’t advance science when stupid people like you can’t take any slight bit of risk. Do you think electricity was safe when people were discovering it? No way, and many people complained, but look at today, electricity is a must-have. Quit being an idiot and denying science, because science is going to move society forward, your stupid government and their pathetic regulations will only hold it back.

  40. Will Jack says:

    Yes, borax in water is great neutron shielding.

  41. Aleksejs says:

    Woah. I was just joking. :) Thought that remembering David Hahn would make everyone smile.

  42. MS3FGX says:

    I don’t know what’s worse, somebody making inaccurate comments and fear-mongering; or a person who admits to doing it and says he doesn’t have any intention on getting accurate information because learning doesn’t interest him.

  43. Erethon says:

    @MS3FGX’s last comment: Well said dude, well said.

  44. Will Jack says:

    +1 Internets to MS3FGX !

  45. M4CGYV3R says:

    There are a lot safer and more scientific ways to build a Farnsworth Fusor.

    The first thing you should do is invest in some lead glass and machine a nice metal(lead maybe) enclosure with a window in it.

    Some places, such as hospitals and dentist offices being torn apart, are FULL of materials from their X-Ray rooms which you can often have just for the asking or small fees.

    You may even be able to find the lead glass there – but bring a friend. Lead and Lead Glass are extremely heavy.

  46. Will Jack says:

    I am still debating whether or not I should make a metal chamber for when I attempt fusion. I may just add steel shielding inside the chamber, along with a borax-water shield.

  47. nnx says:

    you should put a tungsten carbide shield around it to reflect the neutrons, except for a small hole, on which you mount a neutron collimator, use some laptop batteries in a backpack as energy supply, now mount your fusor on your shoulder like a strogg-railgun from quake.
    Now you can go to town and dish out neutron-headshots left and right.

  48. Khordas says:

    What a bunch of ignorant claptrap and paranoia from a bunch of folks who most likely didn’t even bother to read anything at all about fusors first, or get past the ‘oh shit, it’s nooo cuuu laaaar, run!’.

    This is not a dangerous experiment by any stretch of the imagination, other than the obvious, and so far ignored in this thread, dangers inherent in 15 KV DC voltage at non-negligible currents. This is a project that requires a good working knowledge of high voltage, and that’s its primary danger. In terms of neutron flux, it’s really really hard to get to dangerous levels with this. Higher voltage, really good vacuum in a metal jar, and a few refinements are usually necessary before getting more than a few neutrons. Worst case scenario, assuming he gets thousands of times more neutron flux than the average amateur built fusor, you set a bucket filled with water and borax next to it, and mark the neutron shadow of the bucket with duct tape on the floor so you know where the safe area is. You’ll get some neutron activation in certain materials, but that falls off with the cube of the distance so its pretty limited to the jar and the electrodes.


  49. Khordas says:

    @ Stu:

    Apparently ‘Nutjob’ = ‘People smarter than you’

  50. Tomas says:

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