I'm planning to build a small cloud chamber.
The design is the usual: alcohol evaporates at the top by gently heating it with a thin wire and small current. The vapour sinks to the bottom of the chamber, where the temperature is significantly lower than at the top, and causes the vapour to super-cool. Ion tracks caused by fast moving particles can be observed as mist tracks.
My question is about the bottom plate temperature.
The usual design uses a (near) room temperature solvent and very cold bottom plate to achieve a big temperature gradient.
Could a cloud chamber be constructed that would use just a slightly cold bottom plate, and a more aggressively heated liquid? I'm thinking about ethanol or isopropyl alcohol evaporated at 60°C, and a bottom plate temperature at maybe only 0°C
Could this work? Is it just the temperature gradient, or the temperature itself is important?
Best Answer
This is a generic phase diagram :
I looked up the construction of a demonstration for classes cloud chamber using alcohol. For the air/alcohol gas line 3, constant pressure, change in temperature is where you want to work for your cloud chamber. Cooling it without condensation. The gradient of temperature in your chamber will define the thickness over the iced bottom where supersaturation can be maintained. So your choice of alcohol should depend on how slowly the phase diagram changes with temperature as to have a larger distance from the cold plate where the vapors will be supersaturated and tracks can form.
I do not think it is the gradient in the chamber that is decisive, but the one from the triple point to the vapor phase in line 3.The hot on top is to generate the vapour phase in the chamber. It will all depend on the phase diagram of your specific choice for vapor.