Hi Greg,
I can answer that, no, there is not, however you can size a toroid to
the wattage of the system (and I suppose you can size a secondary
similarly, but it is not a direct relationship.) The formula John came up
with some time ago is [top load overall diameter = 0.5 through 0.9*(SQRT
power)] in inches and watts. Something to note, for a normal-ish toroid,
the overall diameter in inches is roughly equal to the capacitance in pF.
I have found this to be very accurate, going beyond 0.9 stops output, and
going below 0.5 gives to many streamers to count. I like to shoot for 0.9
personally... For sizing a secondary I just like to take the predicted
spark length and divide by 2.5, and that is the length, then size the
diameter according to 4.5 to 1 H/D, then size wire gauge for 1200 turns.
Please note, your top load will "look" too big if you do things this way,
but trust me it performs swimmingly... I've gotten used to over-sized top
loads, I'll never go back.
Scott Bogard.