On 4/23/12 7:18 PM, James Hutton wrote:
I have a 5.5inch secondary. could someone suggest a minimum inner primary diameter?I am running low on copper tubing, but at the same time i dont want sparks from the primary to secondary.thanks :) _______________________________________________
I've used somewhere between 1/2 inch and 1 inch. You can always get more clearance by raising the secondary a bit..
The voltage between the bottom of the secondary and the inner turn of the primary is on the order of half the NST voltage (you're using an NST, right), so call it 10kV. If your secondary is 1000 turns and you've got 300kV on it, that's about 30kV/100 turns, which is a couple inches up on the secondary.
breakdown in air is 70kV/inch, and you want to stay, say, 1/3 of that if you can. figure out the distance and see how it looks.
Doesn't one of the tesla coil modeling codes also tell you want the field is? keep the field less than 10-15 kV/cm and you're probably ok.
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