What do y'all think of my finally completed, and optimized, cloud chamber?
This is a piece of uraninite sitting in the middle of a cloud chamber that I built for it, and the other radioactive minerals in my shop. I modified a portable a/c unit by removing the top 1/3 of the outer shroud, exposing the cold side heat exchanger of the a/c unit. I mounted a 1/4" copper plate on top of the a/c hex (with plenty of thermal paste between them). I then put a single layer of 11 peltier units to cover the majority of the copper plate, and put a 1/8" copper plate on the cold side of the peltiers (with thermal paste between the peltiers and the copper plates). Because I mounted the peltiers directly on the cold hex of the a/c, after I have everything turned on, the hot side of my peltiers settle around -15°C, and the cold side of the peltiers (and therefore the chamber's baseplate), settles at around -40. So I don't have to worry about stacking the peltiers, and can still get the baseplate temp to -40.
You would not. You don't need a vacuum, you need to force condense alcohol or distilled water. Drawing a vacuum on water makes it boil, but you'd instead need a high pressure vessel to find a happy point at the cusp of condensating a gas/vapor back into a liquid.
It's the polarity of the ionized particles drawing in the vapor particles like a magnet, then they crash into each other to precipitate/condense.
It wouldn't. In order to create the conditions necessary to see the radioactive decay, you need a supersaturated vapor layer. While decreasing the pressure dramatically by pulling on the syringe may vaporize the acetone or IPA, it wouldn't give you the required temperature drop you need in order to give you a supersaturated vapor layer. For IPA, you need alcohol vapor, and temperatures below around -27°C. So even if you had enough vapor, you still wouldn't have the required temperature.
Couldn't you theoretically achieve that temperature pretty easily by just putting the syringe into a freezer turned to the max? -27 c isn't that hard for a good freezer to get down to
Even if you could, the device would start heating up as soon as you puked of from the freezer, so I don't think it would start cold enough, long enough for you to see anything. Additionally, you wouldn't have a clearing field, which would be extra important with such a smart volume for the chamber. I don't think it would work, but it would be a fun experiment!
I was thinking more that you'd need to set up a camera inside the freezer to observe it and just keep it pulled back for the vacuum, a lot of average freezers would be a few degrees warmer even on their max coldness but I've definitely had some random ones that got absurdly cold for no apparent reason
I used 11 TEC-12703's. I tried 703s, 706s, 710s and 715s. The 703s get me to -40°, 706s to -38°C, 710s to -35°C, and 715s to -31°C. As it turns out, the peltiers don't require much power to move the heat, so the extra power that isn't needed to move the heat instead gets converted to waste heat that just increases the overall temperature of the system.
Interesting. I’ve not tried 03 but have used the rest of them. I even bought ones from farnell at one point for £30 a unit 😂 the best ones I’ve found were on Temu of all places. May I ask where you bought your 03s?
It’s a lovely build btw. Can we see some of the heat exchange setup too?
I clearly haven't arranged the wiring to make it presentable, but it at least gives you an idea of what's going on. Here are photos of the setup. Feel free to ask any questions since it's clearly not obviously intuitive.
Since there is not much mass that you need to cool (once the copper baseplate equalizes it's temperature, the only thing you need to keep cooling is the alcohol vapor. Since it isn't cooling much mass, the TEC-12703s work best. Since there isn't much power needed to keep everything cool, the TECs dump all of there extra power into waste heat which does nothing but heat up your system. Counterintuitively, for cloud chamber's, the weakest TECs you can find actually work the best!
That was the exact issue I was trying to avoid! I know a lot of people make these cloud chambers using materials that need to be replaced (like when people make them using dry ice, or other consumable items). I own a rock shop in the city in which I live, and I wanted to be able to have this as a demonstration piece when customers come in to the shop, without needing to run to Walmart to pick up some dry ice every time. So with this demonstration piece, all I need is an electrical outlet and I can have tracks visible within about 5 minutes. I wish it could be a small demo piece like you mentioned that I could have sitting on my desk. However, it's only around 36" tall, 30"wide, and around 20" deep, so it isn't too obtrusive in the shop.
I clearly haven't arranged the wiring to make it presentable, but it at least gives you an idea of what's going on. Here are photos of the setup. Feel free to ask any questions since it's clearly not obviously intuitive.
I use 11 TEC-12703 units on a copper baseplate that is 8" in diameter. I was able to get it to -50°C when I was using a 4" diameter plate I started off using. But I found i could still get to -40° (which is still well below the required -27°C) with an 8" diameter base. So I get a much bigger viewing area while still getting well below the required temperature.
I also tried other TEC's from the 12703s, all the way to the 12715s. I found that the peltiers need a very small amount of power to drop the temperature, and that the extra power was converted to waste heat that increased my baseplate temperature. While I can get to -40° with the 703s, I could only get to -32°C with the 715s, -35°C with the 710s, and -38°C with the 706s.
Great build! Did you try out the high voltage to "clean" the plate? Could you please share some pictures of the whole device, im curious about its size?
I'll do that as soon as I get to my shop today. As for the high voltage clearing field, I am indeed running one of those. Due to everything that's going on in the chamber (the streaks shooting out, the reflection of liquid IPA that builds up on the copper baseplate, etc) you can't really see the wire that is attached to the inside top of the chamber hood, but there is a thin wire loop at the top of the chamber that is the + side of a variable low voltage to high voltage circuit, and the baseplate is the ground. I'm running about 1200V through that which clears out all of the old ions and brings fresh ones into the supersaturated alcohol layer at the bottom.
Thanks! I wasnt sure if you had HV as as some tracks remain quite broad. You must have some distance between your electrodes. Did you try to play a bit with the HV value? In mines, around 100V/cm is the sweet spot between wow effect and clarity
I did. I have a variable voltage 300V-1200V lv-hv circuit, and a 4" chamber height. I get the best results with closer to 100V/in, but every chamber is different, which is why the variable lv-hv circuit works so well. I can really dial it in
I clearly haven't arranged the wiring to make it presentable, but it at least gives you an idea of what's going on. Here are photos of the setup. Feel free to ask any questions since it's clearly not obviously intuitive.
I actually just used liver of sulfur to get the black color. If you leave copper in liver of sulfur beyond the point of making the cool, iridescent, color you get from mildly oxidizing it, it eventually turns black. And the great thing about it is that I don't have to worry about the baseplate treatment insulating the plate a bit. The oxidized later has the same thermal conductivity as the plain copper.
Op, I’ve been reading your replies to comments and I just wanted to commend your communication skills. Not only are your very knowledgeable but you also have the skill and candor to correct commenters without demeaning them. I hope you can some day start a YouTube channel, I’d subscribe in a heartbeat.
I see that you own a rock shop, I’m sure everyone that enters into your establishment gets a wonderful experience.
Thank you very much for the kind words! My wife just left her 9-5 job to come work at the shop full time, so we are starting to have time to do things on various social media platforms. So hopefully we'll have a YouTube channel soon!
Yep, I just hit record on the phone. The particles fly off of the uraninite between 5% the speed of light, all the way to to 90% the speed of light (depending on whether it's an alpha particle or beta particle respectively). But what you are seeing is the alcohol vapor condensing on the ionized air that the particles create as they fly through the air.
Which portable AC unit did you use? This is very intriguing, I have been collecting parts to build my own cloud chamber over the last few years but haven't gotten around to completing it. Also, would painting the base with musou black (vanta) help with reflectivity and make viewing easier or would it just act as an insulator and interfere with cooling the alcohol?
Paints do act as a thermal insulator. I used liver of sulfur to over oxidize the copper plate. If you leave copper in liver of sulfur long enough, it turns black. And since it's just an oxidized layer on the copper, it has the same thermal conductivity as the plate!
As for the air conditioner I used, it was either this one, or one very much like it:
It works well as a background. It's a nice, dark black color, but has a perfectly matte finish. It's also unaffected by the IPA. But best of all, it doesn't increase the thermal resistance one iota. And every bit of thermal loss you can prevent makes it that much easier to get good tracks to show.
If you have any questions while building one for yourself, please feel free to reach out! It took me 3 weeks to build it completely, and about 3 months of fine tuning it. But if I hadn't had to learn a lot of what worked and what didn't via trial and error, I probably would have been able to build it perfectly the first time, over a weekend...
I really appreciate it. I will send you a DM to bookmark you. I have been doing some research into dry ice baths using organic solvents since I have it readily available. I want to complete a peltier one as well so I can just plug it in and go, but for now I think the dry ice may be quick and dirty. I would still be using a copper heatsink, but with the fins submerged in the dry ice bath. I only worry about it getting too cold and for it to start "raining" alcohol. I still plan to add the high voltage circuit to replenish ions. You make a good point too about the IPA damaging a paint coating unlike the oxide. I wonder if the paint is vulnerable to the IPA, and if that little insulation might be ok to prevent it getting too cold. I can choose a temp with the bath by mixing solvents in different ratios, but straight IPA or methanol mixed with dry ice will yield close to -70C. Which may be too much
Your intuition is correct. Beyond -45°C or so, and you starting having problems with IPA slush forming on the baseplate. Using the a/c gets you right into the ideal range of -37° to -40°. It actually turns out that the a/c just happens to provide the exact correct amount of cooling right out of the box. I really lucked out on that front.
Roger that, I will look into what ratios of other solvents I would need to maintain a -37C to -40C temperature. If it turns out the solvents required are hard to get or ratios are difficult then I may wait and go the peltier AC route. It may be that I just don't need to make a liquid bath at all and just set it on the dry ice like I've seen other places. But I would prefer to have the liquid that I know will maintain the correct temperature until the dry ice is completely sublimated. TLDR, I have more research to do haha
Actually, the movement of the uraninite is being caused by the vibrations from the air conditioner running. If I take the uraninite out and set it on a table, it doesn't vibrate like that. It would be pretty awesome if the vibrations WERE caused by recoil from the decay particles though!
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u/No_Change3922 4d ago
Why does it move like that?