JensenBreck created the topic: Fusor chamber and electrode cooling
I was surprised by this since I really just keep it under a simple vacuum and rarely pump it out. Since I was running it today I noticed that after 30 minutes of very steady, predicable operation, my pressure started to tend upward - this caused by current to also slowly increase. This quickly created an unstable situation. That is, more current created more heat and that increased heat caused a pressure rise which increased the current. Very soon, a runaway situation quickly ensued.
Due to heat build up in my first series of fusion runs about a year ago, I decided to upgrade my chamber with water cooling. My electrode is forced air cooled by necessity (since it is isolated in a large glass plate so thermal contact alone will not effectively cool it.) These cooling systems do an excellent job on both the chamber main body and the isolated electrode.