Alexey's fusor progress

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Richard Hull
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Re: Alexey's fusor progress

Post by Richard Hull »

Another warning about oil seals against a direct vacuum.... "oil finds a way"....

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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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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

Dennis, I would not want the epoxy in direct contact with the plasma in the chamber. This could cause it to break down and off-gas. Fluorosilicone is much more plasma resistant, even better than Viton.

Dennis and Richard, the oil will not get into the chamber because the fluorosilicone seal is additionally filled with one layer of JB-Weld and a layer of epoxy. I am sure that the oil container is absolutely hermetically sealed.

Joe, the triple junction is only at the point where the KF25 flange meets the fluorosilicone gasket. There will be an increased electric field strength at that location, but since that location is inside the hole in the glass I would hope that the discharge would not be able to travel to the chamber wall, since to do so the electrons would have to travel at a 90 degree angle, first down the glass surface and then sideways towards the chamber wall. I think this is very unlikely. In my previous cathodes, the electrode came straight out of the hole in the glass and at that point the current burned a Lichtenberg figure on the glass. Therefore, I decided to increase the length of the electrons traveling along the glass surface and to give the trajectory a curvilinear shape.
It is not very clear to me about the current flow on the polymer surface. I tried to avoid this possibility in the design. Could you please draw this on my schematic?
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Dennis P Brown
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Re: Alexey's fusor progress

Post by Dennis P Brown »

JD weld is epoxy and what I use. It does wear down some but both gets a hard outer resistant coating and offers little significant surface area if done correctly. However, your choice. I think the risk is high with that design vs. the down side of a trace bit of epoxy but it is solely your call. Hope it works well.
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Rich Gorski
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Re: Alexey's fusor progress

Post by Rich Gorski »

This discussion about the problems using oil remind me of a bad experience during my university days in the physics department. Myself along with a couple of other physics students designed and built a 125kV positive ion accelerator. The 125kV supply essentially was a 30kHz high voltage flyback transformer as input to a 20 stage multiplier. Being mostly unsupervised students, on a very limited budget and with very little practical experience decided to use a standard fish type aquarium as a tank to immerse the multiplier in transformer oil. All worked well for more than a year then one day upon returning to the lab we found oil all over the floor. Yep, the seals in the aquarium eventually failed. I guess the oil degraded the silicone sealing material enough to start leaking. What a mess it was to clean up 30 gallons of oil ☹ ☹. I think we went through a few cases of paper towels. However the concrete floor was nice and shiny after that.

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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

I can put vacuum oil in. I have cheap diff pump oil. It is more viscous and has low vapor pressure in case of that magic leak. I think the insulation properties will be similar.
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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

Hello everyone!

Finished a deep upgrade to my fusor yesterday and did a test run. I completely redid the high voltage part, now all the resistors and diode are mod oiled. I also installed new silicone high voltage wires. My oil filled feedthrough isolator is working well, so far nothing horrible has happened and no oil has gotten into the chamber. Voltage adjustment is much more convenient now, all the wire connections are under oil and no corona discharges.
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There was a problem with the chamber wall cooling system, I had to stop the water circulation and as a result the plastic cover melted epically. I'll have to remove it somehow and come up with something else.
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After startup, the inner chamber walls released adsorbed water for a long time, I even thought there was a leak somewhere. The presence of water vapor reduces the fraction of deuterium in the chamber and reduces the reaction yield. To compensate for this I had to supply a rather large deuterium flow - 3-5 ml/min. I observed the process of chamber purification by the const( U*I) dependence on pressure. This is what I mean. I chose -30kV and 6mA as the operating parameters and tried to maintain them by adjusting the pressure via remote control. At the first startup, when there was still a lot of water, the operating parameters were reached at 5 microns, but as I cleaned the chamber I had to increase the pressure and after 1 hour the pressure was already 25 microns according to my thermocouple pressure gauge (thermal conductivity of deuterium is higher than that of water).

After some cleaning of the chamber I decided to try a silver activation experiment. As a detector I used a homemade device of two mica counters under arduino control. This device allows me to start the measurement in 2sec after turning off the voltage on the cathode. These measurements are transmitted to the computer every 2sec. The retarder I made of high molecular weight polyethylene.
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Activation of the silver plate was carried out for 5min at -30kV and 6-7mA. This is quite low power for activation, according to this forum for sure fixation of silver activation (4x above background) you need at least 400W at cathode (at -45kV). So far I am wary of operating at that power due to overheating of the chamber. Nevertheless, I think I have reliably recorded silver activation, at 2x above background in the initial time period. I did 3 activations (waiting 10-15min for complete isotope decay) with the same settings and got the same data everywhere. Of course, it is difficult to construct a qualitative curve from such data, but I tried. I averaged the data from 2 measurements, approximated the points with a step function, and then drew a tangent for the initial time period, and at the inflection point of the curve. The points where the tangents intersect the time axis should give the half-life for the two silver isotopes. For 110-Ag, a close value of 21sec instead of 24sec was obtained, and for 108-Ag the period was 25% longer. It would be more correct to carry out calculations in semi-logarithmic coordinate system, I hope to carry out this work next time on a smoother graph.
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Cinar Kagan
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Re: Alexey's fusor progress

Post by Cinar Kagan »

While this might not be seen enough for the elite fusioneer club, I believe that you have done silver activation.

Happy fusing!

Cinar Kagan
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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

Cinar, thank you for your kind words! I enjoy working with fusor. It's a long-term project, I plan to keep improving my setup.

Funny how the cathode of the two rings created a five-pointed star) usually there are twice as many rays as rings.
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Rich Gorski
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Re: Alexey's fusor progress

Post by Rich Gorski »

Alexey,

Nice attempt at silver activation however in IMO theres not enough evidence yet. Theres nothing to show the 107 to 108 activation and the 109 to 110 might be related to the voltage decay of your power supply. I noticed that you have a large HV capacitor to filter your power supply. My question is, how long before the voltage decays to a level where no X-rays are created? If your start of measuring X-rays from activation is only 2 seconds after supply shut down could enough voltage still be there to create X-rays?

You can handle this is two ways. 1. Wait enough time for the voltage to decay to 3kV or less. What is RC time constant with resistor to discharge the cap? 2. Use lead sheet between silver and fusor so X-rays can’t reach detector. Neutrons won’t be affected.

Also what neutron count are you getting at 30kV and 6 mA?

Good try!

Rich G.
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Re: Alexey's fusor progress

Post by Matt_Gibson »

If you have a Geiger counter, you should be able to pull the silver out of the “oven” and check for activity.

-Matt
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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

Thanks for the comments!

I have been thinking about this issue. The capacitance of the capacitor is 25 nF, but after the voltage is turned off, after 2 sec the voltage drops below 10kV and the detector does not capture the x-ray. The capacitor could be discharged through a voltage control resistor (1.2 Gohm), but that would take forever. This is what happens if a deep vacuum is created in the chamber. Therefore, I believe that the rapid discharge of the capacitor is due to the conductivity of the plasma, its resistance, according to literature data, is on the order of 100 megohms.

However, now I would like to disconnect the capacitor and carry out the silver activation without it. This will establish how useful the capacitor is. To check for residual X-rays, it is easiest to do the experiment without silver)

Due to lack of space on the table, I have removed the neutron counter for now. I still need to optimize the working space.
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Re: Alexey's fusor progress

Post by Matt_Gibson »

I probably missed it, but why do you have the output capacitor installed? I don’t think that regulation is really all the useful for fusors, is it? Seems like an unnecessary liability.

-Matt
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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

The capacitor is needed to increase the number of deuterons with energy 30keV
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Richard Hull
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Re: Alexey's fusor progress

Post by Richard Hull »

I agree with Rich. The sigma in your data is not good. However I do believe you've done it in my heart. However since you said you were in it over the long haul, get some better data as you improve your effort. I am sure you will make elite.

Note that it wrapped my silver and later Rhodium around a Russian STS-5 GM tube (CTC-5) and put it all in the moderator. I ran the tube wires to my Arduino GM setup and read every 5 seconds. I was able to start counting 1 second after shut down of my fusor. check images below

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ActComposite2.jpg
Activation system annotated.jpg
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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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Richard Hull
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Re: Alexey's fusor progress

Post by Richard Hull »

I forgot to put an image of my graph of a Rhodium activation generated from the data pointed read out of the Arduino's EEPROM.

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Bill Kolbs best fit 11-29-20  #2 Rhodium activation.JPG
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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Alexey Khrushchev
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Re: Alexey's fusor progress

Post by Alexey Khrushchev »

I'd really like to get my hands on some rhodium foil to experiment with, but the price of it is extremely high. It is a metal with a history, the great scientists of the past started their work on neutron activation with rhodium. I have a piece of gadolinium, which is a black hole for neutrons, but its short half-life makes it of little use for amateur experiments. I have ideas about it, but not enough time to do them all. By the way, I like to show this experiment - gadolinium is well attracted to a magnet, but if heated a little with a hair dryer, it falls off. The Curie point for this metal is only 292K.

For a long time I wanted to ask - Richard, have you thought about writing a book about your way in fusion and about this forum and community? I'm sure it would be an interesting project to popularize science.
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Re: Alexey's fusor progress

Post by David Kunkle »

And just like that, Paul has his next book project.......
If your experiment needs statistics, you ought to have done a better experiment.

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