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Re: Salt water caps & corona


> I was wondering if anyone could help me out.  I
> recently made some salt water caps.  I have 7 wine
> bottle caps(~1nf a piece), and one bucket cap
> consisting of 4 20oz plastic coke bottles filled w/
> slat water and in a bath of salt water(~14nf total)
> each bottle has ~ 1/4 in of vegie oil and the bath has
> 1/4 in floating on it.  I cant stop the corona on the
> bucket cap.  What should i do.

some tries:

1 - try taking out the plastic bottles and wrapping them in alu foil up to
some inches away from the bottle neck, then wrap in insulating tape.

2 - make three more such caps, then make a 2x2 array, i.e.
	----+--||--||--+----
            |          |
            +--||--||--+
this gives you the same capacitance, but there's only half the voltage
over each cap, which could help to reduce corona. The drawback of
course is that this all gets quite big... But if it is only for
quick&dirty testing it could do the job.
How much kV do you have by the way?

3 - dump the plastic bottle cap, and use wine bottles

4 - make a used transparency sheet MMC (I personally love these, they are
highly compact,they don't in my short experience have too high losses, and
they cost nothing). Or do something similar, a self-rolled cap with some
plastic sheet (was that HDLC, PP, or other plastic?).

5 - use a better cap, go for MMC. Maybe with an assortment of old caps, or
with new bought ones. Search for MMC at www.pupman-dot-com.

> After adding the bucket cap to the winebottle caps
> there was no noticable change in spark length.  Why?

I've had exactly the same experience - firstly the corona causes huge
energy loss, secondly tha glass has additional higher RF losses, and
thirdly with all those losses you have a hard life trying to tune the TC
and it's a bit close to impossible to find the primary tap for better
output as with that corona and occasionally shorting out bottles the
capacitance, thus resonant frequency, changes too...

> I curently have no topload so i assume you can only go
> so far without one.

Oh. Yup, you definitely should try some form of topload, cookie boxes or
whatever. A larger topload let's the voltage rise higher before breakout,
i.e. it will store more energy. Better streamers.

--
*************************************************
 Jan Florian Wagner
 http://www.hut.fi/~jwagner