6 06 2010

All photos.

With the vacuum pump working again, I assembled the fusor and attempted a fusion run last night. It was a day frought with challenges, but in the end the bubble meter saw 4 bubbles in 2 hours and 40 minutes:

This shows beyond a doubt that we have fused the atom. During previous attempts we only produced a single bubble… which suggests fusion, but does not rule out a cosmic ray.

Science Journalist Quinn Norton was at the lab writing a story for Gizmodo. She witnessed and documented the fusion run:

Previously we were having problems with transient voltages spikes or EMFs crashing the data acquisition (DAQ) card. Today was a big test for the new transient voltage suppression system . It FAILED big time. But I learned something in the process.

I began by intentionally creating an unstable plasma to test the transient voltage system.  This crashed the DAQ every time.

Next I disconnected all wires to the DAQ to determine if the interference is coming through the wires or the air:

Without computer control I needed some way to manually adjust  the MFC. I hacked together a quick voltage divider using a 2KΩ potentiometer and a 9V battery:

This proved to work very well.

To control the high voltage from a distance I used the emergency stop button:

This also worked very well. At this point the reactor is completely under manual control. No computer necessary. Which will turn out to be a good thing.

So now we can test the DAQ with no physical connection to the reactor.

Surprisingly, I was able to crash the DAQ every time, even with no wires connected to it!

Quinn noticed the USB hub flickering during the plasma sparks and suggested it may be the failure point. I removed it, and indeed the system seemed less vulnerable to crashing:

At this point the DAQ seems to remain running in the face of sparking plasmas. Good.

Next I tried connecting one channel to the DAQ… a digital output channel to turn the high voltage on and off. I created a duty cycle function in labview to make it easy to bake out the chamber without melting the fusor grid. This is what it looks like running:

Next I bake out the chamber for an hour using a deuterium atmosphere @ 10 mtorr. The high voltage power supply is set to it’s maximum: 30Kv @ 10mA and the duty cycle is set to 75% @ ~ 0.09 hertz.

At first the computer controlled bake out was running smoothly. About 15 minutes in I get a computer crash. Restart. It runs for about 7 minutes and crashes. Try again. 5 minutes and it crashes. The crashes in increase frequency until I am getting nowhere.

At the point I switch the system over to full manual control and begin the metered fusion run. A fresh bubble detector was unboxed and activated.

(so fresh and so clean)

For the main fusion trial the deuterium atmosphere was at 10 mtorr, high voltage set to it’s maximum: 30Kv @ 10mA. The procedure was to run the system at full power until the plamsa became unstable and started sparking. This instability seems to correspond to the grid becoming red hot, so the plasma instability may be due to thermionic emission.

The bubble detector was activated for 2 hours and 40 minutes. The plasma was running for some unknown fraction of that time. 4 bubbles were detected.

Challenges remain for controlling this wily beast with a computer.




17 responses

6 06 2010
Raymond Rogers

I glad you got some positive results!!
“At first the computer controlled bake out was running smoothly. About 15 minutes in I get a computer crash. Restart. It runs for about 7 minutes and crashes. Try again. 5 minutes and it crashes. The crashes in increase frequency until I am getting nowhere.”
This is a bad sign. I would suspect pinhole breaks in some insulation shorting out _something_. These are common for wiring subject to 1-20kv spikes and tightly wrapped. The pinholes start out small and grow with each now incident. I hope you had the TVS hooked to the DAC output.
This can also occur for semiconductor junctions but usually the don’t grow; the just crash.
Thinking about it; I would try replacing the twisted pair attached to DAC output. If that restores the time to crash then the pinhole occurred there. If that’s what’s shorted; then which end of the shield got “grounded”? I think I suggested the TVS end. If so, that was (obviously in hindsight) wrong. Try grounding both ends. This is susceptible to ground loops and magnetic pickup/looping; but offers better protection.
As far as your hub goes; I guess you should try shielding it with a cage or copper mesh. A kludgey proof of principal is aluminium foil (ground to computer frame of course). Another alternative failure is the inductance in the ground wire kicking the DAC and upsetting the hub; and maybe the computer. Getting rid of the hub helped? In any case shortening the ground wire from the TVS to the computer case should help.

High frequency/High voltage impulses just crawl around the system (:

6 06 2010
Raymond Rogers

I know that I am out of date but the bubble chambers I worked around left tracks. Can you give me a link to learn about the bubble detector you are using?

6 06 2010
6 06 2010
Raymond Rogers

bubbletech: Ahh.
I hope you don’t really succeed and blast yourself :)

6 06 2010
Raymond Rogers

One thing: the computer frame connection should be next to the power supply. It actually should be hooked to the green/ground wire in the AC power cord but that’s inconvenient.

8 06 2010
Chris Squibb

That -88708 error is consistent with computer loosing communication with the USB-6008. That will happen if the device is unplugged while the DAQmx acquisition is running, or if something else makes it look like the device is getting yanked.

9 06 2010
Don Cox

The photos are excellent.

Could we have some wide-angle shots showing the whole workshop?

9 06 2010
Neutron Club « Prometheus Fusion Perfection

[…] list of independent researchers that have achieved nuclear fusion, based on the result of our last fusion run. This list is maintained by Richard Hull, the first amateur fusioneer. Counting groups as a single […]

15 06 2010

Have you checked the quality of your building ground yet?

Multi kV spikes need to be catered for all the way down to the ground (i.e the real, true physical earth), not just to the wire coming through the meter.

Find a good earth first or you’ll chase these things forever.

15 06 2010

Good to see your efforts being fruitful.

18 06 2010

Congratulatons! Fantastic achievement!

Am I right in understanding from the account that the plasma was in effect intermittent (pulsed?) in this experiment?

good luck with sorting out that digital rack.

18 06 2010

yes intermittent.

24 06 2010

Also, I should have added a well-done. To get where you’ve got to in that amount of time is truly a remarkable achievement.

I particularly like the idea to get the DA/puter right out of the loop and running it manually when push came to shove … my kind of solution.

A word of encouragement, keep at the grounding problem, computer controls will make things a lot easier and the NI h/ware Labview s/ware should work fine for what you are doing.

(In retrospect, an off the shelf USB hub is probably not expected to be rated for high field environments.)

25 06 2010
Nuke Engineer

Very interesting. Am I correct in assuming that during all of this work, you performed/develop the physics that govern the fusion process as it applies to your particular set up? That being the case, how did the four bubble result compare to your predictions?

26 06 2010
Neutrons / Second « Prometheus Fusion Perfection

[…] / Second 26 06 2010 Our last fusion run produced results we can use to calculate the neutrons per second emanating from the […]

6 07 2010
Press « Prometheus Fusion Perfection

[…] Fusion. This article is amazing – heartfelt and accurate. Quinn was there the night of the definitive fusion run. She even helped run the reactor. It was a night on the cusp. So […]

18 07 2011
Mass Flow Controller Upgrade « Prometheus Fusion Perfection

[…] Previously I used a 9V battery + a potentiometer as a quick hack to control the MFC. […]

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