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I'm trying to build a cloud chamber using a peltier thermoelectric cooler. So far, I've managed to detect some particles, but their trails are very weak (I've used a high voltage generator, about 4kV, obtained from an electrical fly swatter. I'm planning to add a heating element on the top of the chamber to increase the temperature gradient and thus the thickness of the cloud in the active region hopefully. If you have suggestions, they are welcome). The setup is this:

enter image description here

The problem for now is that condensation is produced on the lower part of the plexiglass when the chamber is running. I've tried insulating the juncture of the bottom part using some kind styrofoam, as it is possibile to see in the photo, but the result is the same.

Is there a way to completely prevent condensation on the wall of the plexiglass?

P.S.: Thank you in advance for any answer and please excuse my English, as I'm still practicing it.

MicroservicesOnDDD
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Luke__
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3 Answers3

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Condensation on the outside lower plexi/glass is pretty much unavoidable (unless perhaps your room air is extremely dry). If you image through through the top window, however, this condensation on the sides isn't a big problem. If there is condensation on the top or you are imaging through the sides, the usual solution is to apply an anti-fogging agent to the window. Atmospheric water vapour still condenses, but in the form of a clear transparent film. Commercial cloud chambers typically come with anti-fogging compound, but there are many varieties of anti-fog sprays available for purchase or you can try making your own.

There are limits to what anti-fogging agents can do, however. In particular, if the bottom of the chamber is very cold (which you want for good tracks), atmospheric water vapour can form thick layers of frost on the lowest sides of the chamber.

David Bailey
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First, just try a small fan, a simple stream of air. If that doesn't work, you'll have to go further...

In grocery stores in summer they have a "waterfall" of cold air to walk through that prevents a larger scale loss of air conditioned air through big time convection. You can copy them.

Before you go that far, though, try something simpler first. You can use a tray of desiccant to produce some very dry air, which you would then use to make a thin stream of air. Just blowing this dry air on the surface that you want to keep dry may work.

But if that doesn't work, you can ultimately follow the grocery store "curtain of air" more closely to keep the air around your cloud chamber both cold and dry. Dry enough = no condensation.

The "anti-fogging" idea from the other answer may enhance how well this idea works.

MicroservicesOnDDD
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The temperature gradient in a cloud chamber is affected by the chamber's height; a smaller distance from the dry ice to room temperature (e.g., 1 inch) results in a steeper gradient compared to a larger distance.

Typically, the height is the shortest dimension in a cloud chamber—petri dishes, for instance, are commonly used as compact cloud chambers.

In high-humidity environments, however, preventing condensation and frost on the chamber walls can be challenging. Here are some ideas to help manage this:

Gentle Heat Source: Position a hair dryer on a low setting a few feet away to blow warm air gently over the chamber. Dry Air Injection: Use a can of compressed air (dry air) or a scuba tank with a low-pressure regulator to introduce dry air around the chamber. Double-Box Setup: Place the cloud chamber inside a larger box, leaving desiccant pads in the outer box for a few hours to reduce humidity. You can also use compressed air to displace humid air. As the outer box cools, its outer surface may condense moisture. A larger air mass in the outer box (e.g., a shoebox with a petri dish-sized chamber) will improve insulation. Position the cloud chamber bottom plate in a cut-out hole of the shoebox so that the dry ice sits outside the box while directly contacting the petri dish.

Eric
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