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re. Next step-> Magnifier

Hi Finn:

I can't help you with your magnifier question, but I do have a question
about something you said in that post.

> With the gaps set to 20kV, that`s 16,8 mm (0,66") in my gap, I just
> managed 90 " continous spark from breakout point to grounded rod.

How did you arrive at the gap span vs breakdown voltage?  I must admit, I
haven't a clue as to what my 0.36" gap is charging up to, but I've always
feared that it's way more that what ought to be considered safe for use
with a 15KV NST.

Terry Fritz published a paper on his web site comparing single and multi
gap performance with varying values of k.  Quoting from it:
>The gap is two 1/2 inch copper pipe caps spaced ~0.040 inches apart. The
>primary firing voltage is approximately 5000 volts...

If he gets 5KV per 0.040", I shudder to think what my 0.36" or your 0.66"
gap is breaking down at.  Now I do know that Terry lives at a fairly high
altitude, not sure how much that affects things.

By the way, NICE JOB on your MMC!!!

Regards, Gary Lau
Waltham, MA USA

>Original Poster: Finn Hammer <f-hammer-at-post5.tele.dk> 
>
>I tried to provoke racing sparks by lowering the secondary to K=0.2,
>but  without succes, the sparks just got longer, that`s all. :-) With
>the gaps set to 20kV, that`s 16,8 mm (0,66") in my gap, I just managed
>90 " continous spark from breakout point to grounded rod. However, the
>coil seemed more well tempered than ever, no safetygap firings at all,
>and no self hits either. Also, breakout from the 12"prim. dia. toroid
>was now possible. Random breakouts: now _that_ makes the coil come to
>life for real! Unfortunately, I can`t lower the secondary any further
>without messing the base up, and since the national electricity museum
>has voiced interest in buying it, I don`t really want to do that.
>
>My gut feeling about racing sparks is this: As the coupling is
>increased, the coil gradually takes on the caracteristic of an ordinary
>transformer, where the turns ratio rules. With a relatively low amount
>of turns like mine (800) I can then use a higher coupling than a coil
>with say 1200 turns, without exeeding the interturn breakdown voltage.
>
>About magnifier:
>
>I feel like taking on the challenge of building a magnifier system, 10kW
>pig and suitable rotary. In contrast to the classic TC, which is easy to
>make (anything goes, as long as it is in tune) the magnifier seems to me
>like a *black art*.
>Any help in establishing a fundamental understanding of its function
>would be much appreciated.
>
>Cheers, Finn