Re: THOR's strike rail: how to?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ottalini-at-mindspring-dot-com>

Marco:
        I've been using a combination of these two solutions for quite a
while now
and had good experimental evidence night before last that shielding the
primary
works well to prevent hits.

The disk I use to cover the primary is 1/8" (~32mm) UV protected
polycarbonate
and I wrap a thin 20mil (0.5mm) strip around the outside edge mostly to
protect
the primary from finger and damage (and vice versa!).

Both parts together have been a standard on my coils since the last year or
more, and I have yet to see any primary strikes even with extended runtimes
at power levels up to 4kw.

The last time I ran the coil though, I was doing some last testing before I
put on a new primary that uses 2" (51mm) copper flashing.

I have been using a smaller 5/8" (15.9mm)  wide flat copper primary and
had taken off the top disk and mounted it on the new primary, but wanted
to check tuning before switching.

When I started running, I immediately noticed that there was a great deal
of blue "waterfall" corona hazing the area between my secondary and
primary ... very pretty and all, but not so pretty when it arced across and
then suddenly I was getting small racing sparks only at the bottom of the
secondary where the corona was.  (the damage is permanent now ...
I need to re-coat the secondary again in that area).

The output from my topload was also tending to drive down more than
usual, but since I was only running low power (minimum to medium
breakout ... up to 50" streamers) I wouldn't expect to see strikes anyway.

As for the topload, since I started using the 24" O.W. Landgren toroids
I have seen a tremendous improvement in spark behavior ... denser,
more consolidated (longer), but very interestingly they all stream out
to the sides and straight up, never down.

This may alse be somewhat effected by the topload setup that I'm
now using (UFO style).  The smaller radius of the top "half sphere" may
initiate streamers preferentially at the top.  That top is removable and
there is a copper spike underneath.

I see a more pronounced "out to the side and downish" behavior at very
low power levels, but of course that isn't a problem.

You can see some pics of the horizontal and vertical streamers and the
coil here:
ftp://ftp.mindspring-dot-com/users/ottalini/highvoltage/halopics/

And here is a closer pic of the primary with top disk (with an earlier,
inadequate topload):
ftp://ftp.mindspring-dot-com/users/ottalini/highvoltage/SOCAL2K/

And here is the finished 2" wide primary with the top disk:
ftp://ftp.mindspring-dot-com/users/ottalini/highvoltage/Primary/

Best,
        ko

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, June 21, 2001 6:53 AM
Subject: THOR's strike rail: how to?


> Original poster: "Marco Denicolai by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <marco.denicolai-at-tellabs-dot-com>
>
> Hello all (again),
>
> As you have maybe read, I came to the conclusion that Thor's strike rail
> arrangement needs some modification. I had last week a streamer hitting
> the primary, with catastrophic effects on one of the CCPS drivers. That
> wasn't exactly a nice thing...
>
> You can see my strike rail + primary at
>
> http://www.saunalahti.fi/dncmrc/thorpict.htm
>
> Relevant dimensions are as follows (in mm):
>
> Primary Height (Inner Turn) = 0
> Primary Inner Diameter = 600
> Primary  Outer Diameter = 1100
> Strike Rail Height = 150
> Strike Rail Diameter = 1300
> Secondary Base Height = 200
> Secondary Diameter = 400
>
> I can see three solutions, or a combination of them:
>
> 1. Create a small protuberance on the toroid to originate all streamers
> from a known place. I had for a long time a copper bar sitting on the
> toroid: never got a streamer getting to the wrong place
>
> 2. Vary the strike rail dimensions, height, shape. I have a preatty wide
> area to shield and I don't like the secondary to arc to it. Seems a not
> so easy task.
>
> 3. Place a 20 mm thick PVC disk (actually, two half-moon sections bolted
> together) with some spacers to sit on the top of the primary (maybe at a
> realtive height of 100 mm). Easy to do, also because I don't need
> frequently tuning. Question: would the lost streamers then hit the
> secondary base ?
>
> What is your opinion? Please, let me know.
>
> Regards
>
>
> --
> _____________________________________________________________
>
>  Marco Denicolai           Senior Design Engineer
>  Tellabs Oy                tel: +358 9 4131 2769
>  DSL Products              mobile: +358 50 353 9468
>  Sinikalliontie 7          fax: +358 9 4131 2410
>  02630 Espoo  FINLAND      email: marco.denicolai-at-tellabs-dot-com
> _____________________________________________________________
>
>
>