I am building one. Not for school but for personal reasons. Is anyone here familiar or has built one before? I have some questions such as can the collector be any size? The maxium voltage of the collector is generally .8(70000r) with r being the radius of the collector. I was wondering if I could use a 24 to 30 inch collector with a 15kv power supply, or do I need to bump it up? Scatterd post I apologize.