I've built a simple cloud chamber using a peltier cooling element and I'm able to see some tracks which is really exciting. But now I've seen in many places that you can apply a high voltage between the floor and a ring at the top of the chamber to further improve sensitivity, and also to force activity down into the sensitive layer. My question is, how much voltage would be needed? I have a 2kv ballast to hand which I'd like to try but I doubt if this would be enough for a 20cm tall chamber? Also, I'm a little concerned about the safety of combining high voltage with alcohol vapour - isn't there a significant risk of explosion in case of arcing? Any input much appreciated!