Possibly Fusion

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MatthewL
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Possibly Fusion

Post by MatthewL » Fri Dec 22, 2017 6:46 pm

I have now gotten to a point in my fusor project that I should be able to achieve fusion. I had one problem with my D2 source (electrolysis) in that it seemed to not work very well in terms of gas produced and purity. I then took it apart and built a new one which seems to work better.
IMG_1066.JPG
IMG_1067.JPG
I will mainly let the pictures explain how this new one works, but I will include some further explanation. So in the second photo you can see where the electrolysis takes place. It uses two 1/8 in graphite electrodes at 6 volts to split D2O with a dried sodium carbonate electrolyte. The chamber was machined from delrin and acrylic and has a 1/4 inch glass tube over the cathode to collect the D2. Instead of using something like drierite to dry my D2, I instead use LN2 (which goes into the copper pipe), to hopefully freeze the water and any CO2. I have done some tests and it seems to produce D2, but I am afraid that it is not pure enough. I had done some runs with my fusor in hopes of achieving nuclear fusion, but I did not detect any neutrons with my bubble detector. I have narrowed down some possible reasons for this, and I would appreciate help in deciding what I should do to achieve fusion.
Here is a photo of my current setup:
IMG_9034.jpg
I have made a couple of changes from what is seen in the photos, but nothing substantial.
When I made my runs to achieve fusion these are some photos of the plasma:
Screen Shot 2017-12-21 at 12.15.47 PM.png
Screen Shot 2017-12-21 at 12.19.46 PM.png
Both of these photos are at around 18 microns of (hopefully) pure D2 and about 22Kv.
One problem I seemed to notice when doing these runs is the pressure rising rapidly as my plasma is lit, thus causing my voltage to also drop rapidly. I believe this is due to impurities being vaporized in the chamber, but I have done so many runs at higher pressures and currents that I would have thought that I burned away most impurities. Ultimately this limits a total run time to only around 10-15 seconds before my voltage becomes to low to achieve fusion. This is one possible reason for why I can't detect neutrons. I am also considering the possibility that my deuterium is not pure enough. Does my electrolysis setup look acceptable? Does my plasma look like what a deuterium plasma would look like? I am also afraid that my bubble detectors are becoming too old. I have had them for about 6 months, but in that time I only opened the storage tube once, and they have just been sitting at room temperature in their box. I hope that they still work. If not I do have a PMT and a couple neutron scintillators (Stilbene, LiI(Eu)) that I am planning on turning into a detector.
Any help with these problems or any insight is appreciated.

Thanks,
-Matthew

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Richard Hull
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Re: Possibly Fusion

Post by Richard Hull » Fri Dec 22, 2017 10:38 pm

A pure deuterium plasma is red to red-pink. This assumes a clean view port window. once deposition starts, color fades.

I thick you are getting some moisture in there. It doesn't take but a whisper of it to foul things up.

Richard 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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Dennis P Brown
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Re: Possibly Fusion

Post by Dennis P Brown » Sat Dec 23, 2017 12:23 am

Even if your deuterium had some water vapor, there is no reason your plasma should cause your power supply to steadily drop in voltage like that -generally, trace water vapor in a gas feed is not a contaminate in the fashion that causes steady rises in pressure (as long as it is pumping) unless one already has a significant source of water that is out gassing from the chamber walls. By the way, I ignite a plasma without deuterium but with the residue air in the system as it pumps down (no DP yet, just the two stage mech pump running: I raise my supply voltage starting at around 50 microns - the plasma ignites quickly and strong.) Then I start my DP and get to the mid 10^-5 microns. That way I save deuterium and clean my chamber with a powerful plasma - at a few kV but 30 - 40 ma.

The oxygen you generate in the device from the D2O liquid breaks down, how is that removed or does it just over pressure the cell? In classical electrolysis devices, there are two separate collector feed offs - one for the hydrogen gas and the other for the oxygen. A high pressure cell allows more water vapor into the gas - not a serious issue but consider it.

If unsure of the water content in the deuterium, add a drying agent; you have LN2 so that shouldn't be an issue, I'd think.

A run of 15 sec? That is extremely short amount of time to get a bubble detector to work even if you are having fusion of a few hundred thousand neutrons/sec assuming best case. Considering distance and 4 Pi Radians that isn't much exposure time for the detector. You need to get a stable plasma for minutes to judge the success/failure of the bubble detector I'd think (no experience with these but what I've gathered from reading here by others that they tend to use these for minutes.) Maybe someone with real knowledge can weigh in.

Some here who operate bubble detectors have done so for a year; that is, as long as they are properly stored - sounds like yours was so would be surprised if yours wasn't still working.

MatthewL
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Re: Possibly Fusion

Post by MatthewL » Sun Dec 24, 2017 10:48 pm

I have made a couple modifications to deuterium generator so that I can get a more steady supply of deuterium that is also dry. My first modification was changing the copper tube that would hold the LN2 to a thermos, because my LN2 would boil away to quickly, probably allowing moisture to pass through. I also tried to increase the voltage by putting two 6 volt batteries in series, but my batteries did die at the end of my last run and caused my chamber suck up some water. Luckily the generator's cold trap froze the water before it went in my chamber. I got a run in today that did last for two minutes, and after that run I got one bubble in my detector.
Screen Shot 2017-12-24 at 4.10.59 PM.png
Screen Shot 2017-12-24 at 4.11.16 PM.png
I don't know if this is enough for a neutron club admission. I am not familiar enough with these detectors to know if they would form a bubble that quickly from some other source that is not a fusor. I would think this is a neutron from my fusor, because I checked it before and after a run with the right conditions (pressure (6-7 microns, voltage (24kv)).

I will continue to work with my fusor for better results today and tomorrow. One big issue I have is a stable deuterium pressure. I cannot seem to get my pressure to stay at the right range. I move my butterfly valve slightly and my pressure will drop well below a micron. This is probably due to a very slow leak of deuterium in the chamber. As of right now my generator cannot produce the gas quickly enough. I still need to increase gas production so that I consume at the same rate that I produce. I will try and change the voltage and current to an optimal level. I am using batteries right now. A bench supply would be better and I may possibly have one tomorrow morning. If not, the batteries could still work.
I have one more issue that I think could be an easy fix if I have determined its cause properly. When I am at higher voltage (20kv-30kv), and I am producing a plasma, my multimeter and viewport camera will shut off or just display a very fuzzy image. Right now I am guessing it is caused by electromagnetic fields, and I could fix it with some aluminum foil. If it sounds like something else please let me know.

Dennis, I do have a small hole drilled the lid of my electrolysis cell to allow the oxygen to vent off.

Thanks,
-Matthew

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Dennis P Brown
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Re: Possibly Fusion

Post by Dennis P Brown » Mon Dec 25, 2017 12:32 am

What number of bubbles/mrem is your bubble detector calibrated for?

I, too, know little on Bubble Detectors except what is posted here so Richard can better judge. However, bubble detectors do not respond to environmental (read cosmic ray) backgrounds per posting here in the related FAQ (good to read) so your bubble is most likely from a neutron flux from your fusor.

My fusor was well qualified by my russian BF3 tube some time ago so I know what flux I have (about 80 k neutrons/sec) and as I posted today, I got all of three bubbles in fifteen minutes of operation. However, my bubble detector is designed for very high flux rates (few bubbles are produced even by a lot of neutrons/sec) so the unit isn't very responsive; possibly your's isn't as well or your fusor rate is lower than mine.

Fusors do not appear to provide a large neutron flux at lower voltages; while fusion is possible below 25-28 kV and 6-7 microns pressure and detectable using a good detector system (said russian BF3 tubes), your fusor system is very likely not going to provide you with a strong neutron flux rate - hence, you will either need to raise your voltage, or make longer runs, or do many short runs, or get a better detector (more sensitive bubble detector or build a BF3 or He-3 detector system.) These are really your only basic choices.

In any case, what you have achieved to date is very good progress - you are very likely getting a neutron signal so you should take the next step and get longer exposure times (note my time run for generating just three bubbles was fifteen minutes and I ran for a total of twenty before I had to shut down and leave.) Most critically, do build up a bigger reserve of gas using a small tank of some type so you can extend your runs without feeding off the wet cell. Running a fusor directly off the gas generated by your cell is not conductive to stable operation. That appears to be a major issue for your system.

I am confused (not an uncommon state for me) - are you allowing deuterium to flow into your chamber without a fine control valve? One does not really use a butterfly throttling valve on the DP/turbo to do fine control of the fusor chamber's pressure. Rather, I set the butterfly to hold about 1-2 mircons of gas with said butterfly nearly closed. I then use my fine needle valve on my gas inlet to slowly raise the pressure to my know operation level. Of course I am simultaneously raising my voltage and watching my current. I allow my current to reach a safe load on the x-former, wait for any contaminates to burn away, and then wait for the current to fall. I then raise my voltage to increase my current. I do this repeatably until I reach my max voltage (31/32 kV) and then carefully control my gas inlet leak rate to get the desired current my x-former can support for the time I desire to make my run.

My x-former can handle 60 ma for a few minutes, 40 ma for 30 min, and indefinite for 28 ma. Only limited by my patience. Luckily, I am not limited by my tank - through, that availability of gas may not remain much longer (a few months at best if I work every weekend once or twice. Don't think I can talk the company into selling a gas tank to me again; my tax number has lapsed and not going to do that again - far too much paperwork - lol.)

As for electro-magnetic shielding, Al foil is utterly useless and will not work. Shielded cabling is useful but real, E&M grade shielded boxes are extremely difficult to construct.
Last edited by Dennis P Brown on Tue Dec 26, 2017 11:37 am, edited 1 time in total.

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Richard Hull
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Re: Possibly Fusion

Post by Richard Hull » Mon Dec 25, 2017 6:24 pm

Matthew,

Show us a before picture of a zero bubble reset detector and another after a run with a bubble or two in it and I will add you to the Neutron Club.

I think your issues are related to the deuterium flow or lack of it coupled with a possible purity issue. I do believe you are probably barely doing fusion. Just do another run if you can.

Richard 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
Retired now...Doing only what I want and not what I should...every day is a saturday.

MatthewL
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Re: Possibly Fusion

Post by MatthewL » Wed Dec 27, 2017 9:20 pm

I have finally been able to produce another fusion run with detected neutrons. My bubble detector is rated for 26 bubbles/mrem (2.5 bubbles/uSv). It appears that there are two bubbles from this run, although one is a bit smaller that the other. I am not sure what the cause of this is. My run time was around 30 seconds, and I got my voltage up to 26kv with around 8 microns of D2. My detector was a bout 13cm from the center of my grid. My runs are still limited by an unstable pressure, but I am also limited substantially by what I suppose to be electromagnetic interference with my viewport camera, my multimeter, and now my new DC power supply for my electrolysis system, because once these these things go off I am running the whole system blind.
Here are the requested photos:
Screen Shot 2017-12-27 at 2.53.55 PM.png
Reset Detector
Screen Shot 2017-12-27 at 2.56.01 PM.png
Bubbles after new run
Screen Shot 2017-12-27 at 2.55.41 PM.png
I am going to talk to my school after Christmas break to see if they have an account at Sigma Aldrich and could buy a bottle of D2. My transformer can go to the 40-45kv range, but I am limited right now because of not great rectifier diodes and nothing to deal with corona leakage or arc overs at higher voltages. I appreciate all of the help that I have gotten to get to this point. I will continue to work towards higher neutron numbers.

-Matthew

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Re: Possibly Fusion

Post by Tom McCarthy » Wed Dec 27, 2017 9:49 pm

Can't say much about the bubble detectors, but the rest of your system looks great. Congratulations.

If your school doesn't work out, do try contacting someone (preferably family friend/is inclined to help out) who runs any sort of business and ask them can they give you the details to set up a Sigma account, if you have legitimate details, Sigma may fulfill order without much hassle.

Tom

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Richard Hull
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Re: Possibly Fusion

Post by Richard Hull » Wed Dec 27, 2017 11:08 pm

I have added your name to the Neutron club, (high school fusioneers). Buying real bottled D2 is the quick and definite way to do a lot of fusion with the good setup you have.
Good luck.

Richard 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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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