# Re: HV Arc Resistance

Hi Nick, all,

> Original Poster: NickandSim-at-aol-dot-com
> just an idea....
> > My "just use 3 ohms" rule is far over
> > simplified but I don't know of any better way for the normal person
> >(hey, I'm normal toooo :-o) to find the real number here...

> I may be over simplifying, being naive or generally showing my age
>(14) but I thought there was a perfectly good equation for the
>impeadance of an inductor with negligible DC resistance at different
>frequencies:
>
>   Z = wL
>
> w=(used here as 'omega') 2 * pi * F
> L=inductance in henries

Actually you are niether naive nor showing your age. I always enjoy
inquistive "youngsters" It reminds my early days ;o) (Okay, I´m
exaggerating a little here, as I am only 30). No, really, it isn´t all
that clear or easy to understand. We are not looking at the
impedance value (AC resistance), but rather the "apparent" DC
resistance of the primary. This is very difficult to find, because a
lot of factors (like Terry just answered to my mail, if the
secondary is removed, we actually change (lower in this case)
this "apparent" resistance). It is (to me) not fully clear what all
the factors are, that go into this equation. Ideally we would want
to have zero ohms. In the real world we will NEVER reach this.
This resistance is the *real* factor on how much energy we can
pass through the primary, caps and all.  The higher Rpri is, the
higher the losses will be and the worse the output will be. There
are other things, too. If you remember the last posts, you will
recall the post about changing the tank wiring (I mean the post
about TVI, etc). This, too, affects the output spark length. This
is one of those things, where you need to simulate and
backcheck against (a lot of) empirical results. If we could fully
understand this and what the gap really does, at the same
rate that the MMC is evolving, we might be able to produce
mega-sparks from mega-small VA´s. On the other hand, once
you know everything, life becomes uninteresting ;o)). This
is another subject, which is of great interest to me, as I am
using a low (high) voltage source and will be pumping kA, so
I want my RLosses to be as small as practiclly possible.

Coiler greets from germany,
Reinhard