New Fusor - Prototype Test

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Dennis P Brown
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Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

New Fusor - Prototype Test

Post by Dennis P Brown »

I installed the new chamber window and electrode (see image.)

I tested my new fusor and power supply this morning to really great success. The vacuum system got to the low 10^-5 torr (for trace gas removal); and I was able to use my gas 'leak' valve to set any pressure between 1 and 25 milli-torr in the fusor.

The power supply worked extremely well and I'll discus that in the fusor power section post. Don't have time for any significant testing this early morning (before work) but was able to get a stable, uniform plasma between 6 and 15 milli-torr depending on voltage settings. The system was run on air rather than deuterium because it was just a test. The deuterium system, as posted previously, is complete and ready to hook up when I want a serious test - maybe tomorrow. May also try my experimental neutron detector just to try it - not expecting any real results without a more careful setup/run.

I use the standard "star" ground system for all electronics/systems but also have a second, independent ground on the fusor and high voltage power supply for redundancy.

Did notice the high voltage input electrode got a bit warm after a few minutes of operation (and to think someone once argued with me that a small spark plug could 'easily' handle those levels on a continuous opperations even at the upper levels of power (lol) - my electrode is 10 mm in diameter and it is heating up!) I guess I'll need to add some copper cooling rings on the input electrode and install a fan system to better dissipate the heat - the fusor power supply does produce over 700 watts, even at's it mid point settings.

The entire system operates extremely well: all controls are convenient to access/operate, and as mentioned, the plasma is very stable. I can easily 'select' parameters that provide a given voltage and current. My controls are: variac for power/voltage; gate valve to the diffusion pump for total flow rate control; leak valve for pressure control (and indirectly, fusor voltage setting.)

All that is still to do is add my palladium coated steel "grid' system to the end of the electrode, and hook up the deuterium tank. Then I can do a full "fusion" type test - of course, until I have a neutron detector, that is just speculation but still, nice to get well into 'typical' fusor voltage/power/pressure levels.
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New Fusor System - Power Supply (left), Fusor (left)
New Fusor System - Power Supply (left), Fusor (left)
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Dennis P Brown
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Re: New Fusor - Prototype Test

Post by Dennis P Brown »

Further progress and learning; realized (after the fact, sigh) that the electrode for the anode is too close to the glass cover. At high voltages (15 - 20 kV, 30 - 50 ma), metal sputters onto the glass, and then, as I adjust parameters to get close to 'ideal' fusor conditions - 25+ kV, 25 - 35 ma), I get a runaway effect as the voltage drains along the metal/glass vacuum side surface and 'short's' out my plasma (the x-former doesn't seem to mind and continues to up current ...not ideal.)

So, I need to redesign my electrode and anode system and move it further from the glass view port. To do this, I removed a metal 'shield' (a cold plate system that remained in this surplus chamber- since it had external piping for coolant I was reluctant to break these lines. They are now cut off and sealed with epoxy.) My chamber's central region is no longer obstructed and I can now re-install the electrode further from the glass view port.

I did get a 'star' plasma mode (see photo; current: 35-40 ma, voltage 22-25kV) as I got close to the required fusor voltages/pressure/current but it was far from as clean as others here have posted - liklely due to being too close to the glass plate and also, my chamber needs more plasma time to etch away contaminates - but still, progress is progress. I will say the x-former has no issues even with 45 to 55 ma when the voltage is in the 25 -30 kV range. Needless to say, I back it off at those extreme's. Still, this x-former has very high current capability (It has max out my milli-amp gauge a few times; that gauge reads up to 60 ma) even in the 28-32 kV range.

I did ground the 'leak' valve, and added a powerful fan to blow air onto the x-former. These upgrades add to safety and, hopefully, reliability. I am rather pleased by my central 'electrode'. It was made from a single piece of steel welding rode, by bending this along a metal pipe. Then inter-lacing the "circular sections. No welding required! Took about 20 minutes to make including using fine tungsten wire to 'bind' together the top of the loops (not really required but helpful.).

May or may not have time to construct, install and test the new electrode assembly before I leave for Germany. Will see - hopefully; be fun to hit fusion conditions even if my neutron detector isn't able to work.

I will add a short operation note that I am sure others have already posted but new for me since I am 'feeling out' my system and its oddities. I discovered that for my system, setting a high pressure of deuterium (20 microns or so) and then adjusting the gate valve and deuterium feed (also pre-set to a 'known' value that allows the system to hold the 20 microns pressure) to allow the pressure to fall to a lower valve. This enables me to slowly up the voltage & current in a very controlled manner (that is, until I had hit the sputter flash over point, lol.) In a 15 - 20 kV area, I was able to easily control the current for a given voltage.

Aside: I held the system at 2.5 * 10^-5 torr for an hour or so before running this test. A bake out might be in order but that is definitely for next month when I get back and have some time.
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Star mode to date (first time I've got this plasma structure)
Star mode to date (first time I've got this plasma structure)
Last edited by Dennis P Brown on Fri Aug 19, 2016 5:55 am, edited 1 time in total.
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Richard Hull
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Re: New Fusor - Prototype Test

Post by Richard Hull »

Dennis, I have placed you in the plama club. Nice work!

Richrd Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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