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Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 9:15 pm
by Dennis P Brown
I too used a bubble detector to first determine that a smaller chamber does, in fact, lead to greater fusion. I did this about a year or so ago. I am glad to see this work taken further and with better accuracy. I agree with Richard, and why this also caught my attention for confirmation - smaller chambers (i.e. distance from cathode to ground and higher deuterium operating pressure) does result in significantly higher fusion rates. Your results are very good and effort outstanding.

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 9:43 pm
by Dan Knapp
Joe

Can you explain your magnetic field plot? This appears to be a half image of the cross section of two ring magnets (that would also be cathodes?). Is this correct?

If so, it is not clear how you would get magnetic shielding with the field lines terminating on the cathodes.

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 9:55 pm
by Joe Gayo
The cathode is in the center along the axis of the magnetic field (the plot is oriented vertically but the actual layout is horizontal)

(P.S. I'm working on a paper that I planing on submitting to a journal to discuss this system.)

Re: Joe Gayo's lab tour

Posted: Wed Jun 19, 2019 12:09 am
by Robert Dwyer
Neutron counts into the 1e7 range with a smaller chamber! Wow! I never though I would see it. This is a great system. It is cool to see that you are using software like FEMM to investigate your fields. It would be interesting to see plots of the E-field in your setup as well.

After going back through my data and reading some articles, I had gotten the mindset that the high operating pressures were in fact hurting as the ions would collide with too many neutrals not allowing them to reach higher energies. It appears I was wrong. Perhaps these systems want more power (voltage and current) in the high pressure regime, or perhaps my old system was not clean enough to see the big numbers... Either way, great job.
Of course you also have that background field, who knows how much of these improved numbers come from each of things, or any combination of these things.

Re: Joe Gayo's lab tour

Posted: Wed Jun 19, 2019 12:21 am
by Joe Gayo
How about a PIC simulation that shows the time evolved potential field:
https://youtu.be/wEO5Ewo_H_w (Note: The cathode is at 0V and the chamber walls at 50kV)

Re: Joe Gayo's lab tour

Posted: Wed Jun 19, 2019 3:30 am
by Scott Moroch
I was interested in your 7-hole grid design. The models support the observations.

Simulation Video: https://www.youtube.com/watch?v=P5lp3Wu ... e=youtu.be

Initial distribution is circular, launched from the left with 0 KE. Grid at -60kV with respect to the chamber.

Re: Joe Gayo's lab tour

Posted: Wed Jun 19, 2019 12:16 pm
by Rex Allers
So PIC simulation is new to me. From a little searching I assume this is
particle-in-cell computation, a method for simulating plasma.

This wiki covers the basics -- https://en.wikipedia.org/wiki/Particle-in-cell

Looking at your plot in the youtube link, it seems the simulation only represents a quarter of a slice through the whole device. Symmetry means the fields in the other three quadrants are just mirrors of the one calculated.

Not needed, but I captured one frame from your video and did the mirroring of the main plot window, so the field in the whole device would look like this.
PIC sim full.png
I assume the elapsing time as the video plays reflects actual time for the plasma to evolve in the chamber. Does the simulation give the actual time represented across the video?

I have one small question about the voltages. You said the chamber was at 60 kV. Looking at the sim plots, the two edges that seem to represent the chamber edges appear to always be at 50 kV. As the fields evolve some areas get up to 60 kV but those outside edges are still at 50 kV. Does this mean the external excitation voltage applied is 50 kV?

What software did you use to run this?

Thanks for sharing.

Re: Joe Gayo's lab tour

Posted: Wed Jun 19, 2019 4:00 pm
by Carl Willis
Joe, this is a top-flight effort, and I am thrilled to see what appears to be a novel paradigm in fusor efficiency developing in your work.

The regime of high pressure, small electrodes, high potential, and high neutron yield is undoubtedly a new domain worthy of further attention.

Have you provided a detailed discussion of your electrode geometry on this board? I apologize if I missed it; I have mostly been away from the forums the last few years. But it's progress like this that will make me come back!

Thanks for sharing your impressive project here.

-Carl

Re: Joe Gayo's lab tour

Posted: Wed Jun 19, 2019 6:02 pm
by Joe Gayo
@Rex Yes, in this simulation the applied potential difference is 50kV. You are correct about the symmetry of the simulation as well. The animation represents microseconds. The software is Starfish (https://www.particleincell.com/starfish/ - Free!)

@Carl Thanks! The electrode geometry is discussed in my lab tour video on YouTube. I'm constantly refining the electrode geometry based on simulation and testing. The next "knob" to turn will be material selection.

Re: Joe Gayo's lab tour

Posted: Thu Jun 20, 2019 9:08 pm
by Jon Rosenstiel
Joe,

Awesome work, and congrats on the ultra-mega neutron numbers, you are the man! After many, many years the baton has finally found a new home... about time! And you didn't just up the ante a little bit, you blew it to smithereens!

In your video you mention that your device's neutron output on axis with the plasma beam is about 2 times that of the neutron output measured at right angles to the beam. As your device is not truly isotropic in neutron output it may be more accurate to quantify neutron flux in neutrons/sq-cm/second.

Jon Rosenstiel

PS: Anyone have a foot or so of 4" x 4" 6061-T6 bar stock they wanna part with?