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Re: Recent s.s.t.c. work

Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>

Dmitry (& all)-
Those are fascinating images! But I don't think I can agree that adding the LDPE necessarily makes things worse: is not the voltage present on the primary relatively small--perhaps just a few thousand due to resonance? That should not introduce so much electrical stress in the LDPE as to cause problems. And it does appear that the secondary is still "pristine", as to electrical stress areas.
Try interposing a slightly-electrically-conductive sheet between primary and secondary. Someone who used to be active in Tesla coils had found that slightly-conductive strips pasted longitudinally onto the outside surface of the secondary got rid of the tendency for turn:turn sparking. Maybe there would be such an effect for the primary. 

Thanks for the links to FEMM; I'll look into that.
Yes, inside I'm not so old. But still, the gradual aging of the outside becomes a bit of a nuisance. Perhaps you know the feeling. 

Here's wishing you fair weather, in Novosibirsk.

Ken

Tesla list wrote:
Original poster: "Dmitry (father dest)" <mailto:dest@xxxxxxxxxxx><dest@xxxxxxxxxxx> 


> Original poster: "K. C. Herrick" <mailto:kchdlh@xxxxxxx><kchdlh@xxxxxxx>

> Dmitry (& all)-

> You're right about conserving the motivation; I'm going to be loafing
> for a while--and perhaps I'll even fool around with Bela while I'm
> loafing.  And thanks for the mention of that; with a bit of looking
> via Google I found & downloaded it.

read this:

"Finite Element Method Magnetics
David Meeker

Version 4.0 16Sept2003 Development Release:

Few changes in solver functionality have been implemented since v3.3 in this
development release.  The significant change is that the magnetics pre- and
post-processors and the electrostatic pre- and post-processors (previously
known as the separate program, BELA) are all incorporated into one
"interactive shell."

today i`ve downloaded the FEMM40 - there`s more materials in built-in
library, plus some new convenients appeared  - i recommend it. the
author says:
<http://femm.foster-miller.net/Archives/faq.htm#tth_sEc21>http://femm.foster-miller.net/Archives/faq.htm#tth_sEc21 

"21  Where can I find FEMM 4.0?
FEMM 4.0 is no longer available. FEMM 2.1a through FEMM 3.4 and BELA
1.0, which were released under the Aladdin Free Public License, are
still available for download from <http://femm.foster-miller.net>http://femm.foster-miller.net."; 

but you can download the program here:

<http://groups.yahoo.com/group/femm>http://groups.yahoo.com/group/femm

in the "files".

> The image at the link you give below looks rather nasty: there's
> apparently lots of field stress right at the poor old
> secondary.

frankly speaking there`re no problems with the secondary - today i
found a mistake in one conductor, the corrected picture looks like:

<http://cis.ru/~dest/1.PNG>http://cis.ru/~dest/1.PNG

note that the problems are with the primary, as its ROC is
rather smaller - the secondary is a plane in fact.
let`s add a 1cm of the LDPE sheet beetween the primary & secondary -
the immitation of the secondary former:

<http://cis.ru/~dest/2.PNG>http://cis.ru/~dest/2.PNG

everything became much worse :o)
now we`ll add more LDPE - the primary side insulation:

<http://cis.ru/~dest/3.PNG>http://cis.ru/~dest/3.PNG

it`s terrible at all %-)))
i don`t know by now how could we set the boundary conditions precisely
to obtain the quantitative answers, but at least qualitative my charts
are correct i guess, so we can try to model the different ways of
"field control".

say, it`s well seen that the attempt to cover the problem area with
the small piece of insulation caused nothing good:

<http://cis.ru/~dest/11.PNG>http://cis.ru/~dest/11.PNG
http://cis.ru/~dest/12.PNG

> I/we may well conclude that, simple & boring thought it may be, the
> flat primary is the safe & easy way to go.  At my age I'm all for
> safe & easy; so why am I still doing this??

probably "inside" you not so old, and this is the main thing ;-)

-----
Happy coiling, unlimited electricity, basic food and requisite sleep.
21-06-1996 (c) Robert W. Stephens