Open Joint Design

17 01 2010

Doing some work on the design of the open joint superconducting magrid, which looks like this:

The lids would need to have integrated covers to cover the open face joints. This is turning out to be a challenging design problem. I’ve gotten this far:

Nerd Nite

13 01 2010

I’m giving a presentation on my fusion research at nerd nite this Friday the 15th around 8pm.

Nerd Nite NYC

Galapagos Art Space DUMBO 16 Main Street in DUMBO Brooklyn (F train to York St. or A/C train to High St.)
Friday January 15, 2009 at 7pm (Quizo) and 8:15pm (regular Nerd Nite)
Fusing the Atom and Living to Tell
Description: We have built an open source nuclear fusion reactor and fused the atom. This is the story of a remarkable fusion device called the Farnsworth Fusor and its successor, the Bussard Reactor (aka. Polywell). The Bussard Reactor holds the promise of clean cheap abundant energy from fusion. This is a story of research on the edge.
Bio: Famulus is an entrepreneur, hacker, and rails developer. In 2008 he learned of the Bussard fusion reactor and left the software world to try and build a working Bussard Reactor.


12 01 2010

I recently came across todayandtomorrow, a mind blowing contemporary art blog. It made me want to paint. I painted:

Oil on masonite.

Electron Gun

12 01 2010

Yesterday I was at the lab (which is absolutely freezing, the boiler is broken). I installed the electron gun:

I fumbled the flange when I was removing it, and broke the ceramic tube. Ugg. I’ll have to make another one.

Notice the ceramic’s discoloration from the plasma of the Fusor. Why? Plasma is corrosive, but still rather surprising to see such a dramatic change.

Unfortunately, I installed this incorrectly: a centimeter of the lead wire is unprotected by ceramic. The plasma was forming around this lead.

So I’ll have to open the chamber back up and try again. I think it’s time to invest in a powered torque wrench. Doing the large conflats by hand is a real time consuming pain in the ass (and knuckles when the wrench slips).

Another useful upgrade are these plate nuts:

These are metal plates with two threaded holes, shaped to match the corresponding CF flange’s bolt hole patterns and replace the individual nuts. The plate nut’s major advantage is, once two bolts are manually started, the plate nut acts as its own backing wrench and washer—the bolts are tightened using one wrench.


12 01 2010

My friend jewelry designer Max Steiner designed this amazing necklace based on a Fusor’s grid for a Kickstarter fundraiser I hope to launch soon:

Coil Former and Electron Gun

6 01 2010

It’s looking feasible to run the Sydney experiment. The pieces I need beyond my current setup include:

  1. teflon coil formers
  2. electron gun
  3. coil drive electronics
  4. Langmuir probe

The coil formers will be turned on a lathe. I’m going to refer to these as coil formers, because unlike a magrid they do not carry a positive high voltage potential. The 2.5″ teflon rod arrived yesterday:

The electron gun is pretty straightforward. A metal cylinder placed at -10 kV in a few millitorr of hydrogen gas will produce the beam that you see in the Sydney experiment. I’m about to braise this copper tube to a lead to make the electron gun:

The coil drive electronics: Provided I can get the schematic, assembling the coil drive electrons should be straightforward.

The Langmuir probe: Still waiting to get quotes. Although the Langmuir probe looks pretty complicated, hopefully a commercial product will allow me to approach it as a black box… just a tool for taking plasma measurements. This exploration will force me to delve deeper in to plasma physics.


Joe Khachan has the following to add:

You are probably better off tapping a hole in the cylinder for the electron gun and screwing the stalk into it. This will get hot and brazing might melt. Another note, commercial langmuir probes might be a little limiting since they are made for the plasma processing market and will scan between -100 and 100 V. The polywell will be dealing with greater voltages than that. We make ours, which is a simple construction. Just a very thin wire (the width of a human hair) inside a ceramic sleeve, about 10 mm of the wire is outside that sleeve at the center of the polywell. You can find details on the web since many people make their own. For floating potential you can use a high voltage probe connected to the langmuir probe wire and the output of the high voltage probe goes to the oscilliscope, which is what we were using. These are the time varying potential that you see in our powerpoint presentation. After you’ve finished, you will find interesting behaviour in the well depth as you change the current in your coils.

Another note. The electron gun relies on the natural break-down of the gas in your chamber like gridded IEC. The breakdown voltage and/or pressure will depend on the size of your chamber (if you don’t have another ionizing source). You may have to increase the pressure until you get breakdown – then you can reduce it after that. You want as low a pressure as possible since the electrons are trapped for a long enough time to collide significantly with the background gas and therefore lose energy and therefore potential. If you have to go above 10 mTorr then so be it. You should still see interesting behaviour.

The langmuir probe should be the simplest of all that has to be done. Just ignore the wikipedia page. The maths makes it look bad. It is just a wire connected to a voltmeter (for the floating potential). You just need to shield most of the wire with a ceramic sleeve and only have 5mm to 10mm exposed in the plasma – that’s it. You will need electrical feedthroughs on your vacuum chamber so that you can connect the langmuir probe wire to the outside world.

Langmuir Probe

4 01 2010

If you wish to replicate the Sydney experiment, you must first obtain a Langmuir Probe.

I have requested quotes for these commercial Langmuir Probes:


Automated Langmuir Probe (ALP) System


BTW, how do you pronounce Langmuir? I imagine it rhymes with “pang-doer” or maybe “ma-doer”. ANSWER: it rhymes with lang-meer.

Q&A with Joe Khachan about copper coil Polywell

4 01 2010
To gather more information on the Sydney copper coil Polywell, I emailed the project leader Joe Khachan with some questions:


Q) What journal will this research be published in?
A) We haven’t decided yet.


Q) When will that journal article be published?
A) We have not written it. We need to obtain some final results before publishing.


Q) Is your ceramic magrid made from off the shelf parts?
A) The formers for the coils are made from Teflon. This is readily available and easy to machine.


Q) Are the copper coils in your magrid at positive potential or ground potential?
A) They are floating. The coils are not running at high voltage. Moveover, they are made of enamelled copper wire so biasing them will not help. By floating I mean they are electrically isolated from the whole system. The cathode that produces the beam is negative with respect to the chamber. A better way to do this is to make the Bussard polywell, where the rings are biased positively. As I say, we are doing it in this way to understand some of the physics before committing ourselves to a final design. The way we are doing it enables changes to be made very quickly.


Q) Are you only injecting electrons at this point? no deuterons?
A) Yes, electrons. There is hydrogen background gas in order to produce electrons from it.


Q) Why is the electron beam entering the magrid at an angle instead of being aimed right in the center?
A)That was one particular experiment of many. Other experiments had the beam going in normal to the faces. One reason for the angle is so that the electron beam doesn’t touch the langmuir probe at the center. Other reason is to see if the depth of the well changes with angle of beam.


Q) How are you measuring the depth of the electron well?


Q) What are you using for your electron gun?
A) A metal cylinder (as shown in the photo) placed at -10 kV in a few millitorr of hydrogen gas will produce the beam that you see.


Q)  How deep was your vacuum prior to electron injection?
A) Our base pressure is 10^-3 millitorr but we operate at a few millitorr, so we are not replicating Bussard’s polywell exactly since he operated at lower pressures, but at a few millitorr we can gain valuable insights before committing ourselves to a more involved experiments.


Q) What are the dimensions of the magrid?
A) The dimensions we have are quite arbitrary and are unlikely to produce any substantial fusion at this stage since the well may not be deep enough. However, the space between the inner faces of the spools is about 5 or 6 cm – very small.

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