Max's Reactor: Got a Gorgeous Plasma

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MaxfieldFrancis
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Max's Reactor: Got a Gorgeous Plasma

Post by MaxfieldFrancis »

After much trial and tribulation I believe shes ready for fusion. I switched out my original mild steel inner grid for a nice stainless coil. Instant improvement.

First plasma:
IMG_20220412_132515338.jpg
Second Plasma:
IMG_20220413_172655_563.jpg
Matt_Gibson
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Matt_Gibson »

You’re getting there. You’ll need to get your pressure down much more than that though. Looks to be in the 50 micron range?
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Dennis P Brown
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Dennis P Brown »

Are you evacuating the chamber to the low 10^-4 torr range first?
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Richard Hull
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Richard Hull »

Without a proper electronic TC gauge, you have no idea where you are in vacuum. Looks like 100-200 microns to me. To do fusion you need to start admitting gas into a vacuum about 1000 time deeper than you are now! (100 times deeper at an absolute minimum)

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
MaxfieldFrancis
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by MaxfieldFrancis »

I do not have a high vacuum gauge. There is definitely a small leak in the chamber, however I do not know where exactly. Probably one of my copper gaskets. I will leave my turbomolecular pump on for longer, I believe it was only on for a few minutes before I took this picture. I do not want to spend more money unless I absolutely have to, so Ill chase the leak before buying a TC gauge.
Matt_Gibson
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Matt_Gibson »

How do you know that you have a leak without a gauge? Going by plasma appearance?

I may be wrong, but you could be really over working your turbo if it can’t get you down below 100 microns.

I’d plan on getting a TC gauge asap.

-Matt
MaxfieldFrancis
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by MaxfieldFrancis »

Thanks for the input Matt. I have left the chamber pumped down overnight and it has returned to atmospheric pressure each time. This slowed greatly when I put new viton gaskets in, however the chamber's pressure still slowly raises to atmosphere.
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Dennis P Brown
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Dennis P Brown »

A chamber rising to atmospheric pressure after just a single night is a significant leak. I get upset (and look for a leak) if mine exceeds one torr overnight (out gassing can easily do that but for a clean system, no.)

New copper gaskets, unless the knife edge is compromised via damage/scratch or one didn't tighten in a proper sequence, should hold an excellent seal. Did you examine all knife edges on the various surfaces to determine they are pristine/undamaged?

A pic of your setup would help people here get an idea of where problems might arise.

TC gauges are not expensive (good deals appear from good sellers on ebay.) Yet a TC is only partly useful - most leaks, unless very significant, aren't easy to trace with just a TC; however, it will give you direct feed back after you make arbitrary repairs. If your turbo is running and you aren't even under 100 microns certainly that leak is very significant and you might be able to here it


A high vac gauge (once you get below one micron are extremely good at locating leaks using either alcohol or the dry air "Dust Off" cans. But one must get to at least that level before 1) small leak detection is possible 2) min. vacuum needed to run a fusor
MaxfieldFrancis
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by MaxfieldFrancis »

Thank you Dennis, I mitigated the pressure increase quite a bit, the chamber now returns to atmosphere after 4 days. Not ideal, but far better.

After only a small amount of tweaks I am now able to very quickly pump the chamber down far past the necessary pressure where the bugle jet disappears. Currently I am learning how to balance the vacuum pump outflow and the gas inflow. If I don't close the butterfly valve enough, the pressure gets too low and the plasma is snuffed out. I will be fixing the leaks at the electrical feedthrough, gas inlet, and gauge valve, however my viton gaskets are functioning exceedingly well and unless absolutely necessary I will not be replacing them with copper.

My physics teacher and I will be fully testing the system, and introducing deuterium into the chamber, for the first time today, at 3:00 PM. Until then I plan to fix the stray leaks and clean the chamber internals. I will keep you all updated. Thank you for all of your help and guidance.
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Richard Hull
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Richard Hull »

You are getting there. The key thing is that all plasma disappears due to the depth of your vacuum. Still, with higher voltages it might relight. When my fusor is in perfect running order with 5-6 microns of gas, it will only relight at 22,000 volts applied. At that point it will slowly re-extinguish unless I raise the voltage even more. And so it goes. More gas, more voltage. fusion begins at about 25 kv for easy detection.

A demo is quite different as rarely will the voltages ever exceed 10kv, but more often 5-8kv. Demo fusors rarely have a secondary pump, like a turbo or diff pump.

Be it demo or real fusor the battle is always gas/pressure/voltage balancing against current draws that the system and its power supply can survive.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Dennis P Brown
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by Dennis P Brown »

From "zero" to 760 torr in four days means one has a leak rate of almost 8 torr an hour or slightly over 2 microns a second. That will represent a significant amount of gas for a fusor run - assume 10 microns provides the require plasma at your typical voltage - then that is a fifth of your partial pressure is air. That seems rather high. If you are doing a demo, not an issue. But if you want to do fusion in the future, something to think about.
MaxfieldFrancis
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Re: Max's Reactor: Got a Gorgeous Plasma

Post by MaxfieldFrancis »

I think I've sealed it. It no longer returns to atmosphere after four days,. I am aiming to do real fusion, I am hoping to test it today. I just had to hand in some measurements to my principle. There was some pretty bad outgassing after oil got pulled into the chamber, but its all cleaned up now
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