Re: Jacketed Coil

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

David,

I once saw a high performance minicoil at a Teslathon about 5 years ago
that used a 1" coilform surrounded by a larger diameter clear plastic
tube, with the space between completely filled with white mineral oil.
The outer diameter of the secondary was perhaps 1.5" in  diameter. The
system was driven by a small unpotted NST, and generated streamers about
24" long - a really sweet little coil! 

If you want to stop corona breakout from the top of your secondary, you
should consider adding a small toroid at the top of the winding to help
shape the e-field and shield the top of the winding. Using oil around
the winding helps "spread" the effective diameter of your secondary and
smooth out high e-field stress at the top of your winding. While it will
prevent corona for relatively small spark lengths, I suspect you'll find
that it will not be effective at higher power levels.    

Best regards,

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Coins Shrunk Electromagnetically!
http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "David Thomson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>
> 
> Has anybody here built a jacketed coil before?  I'm just finishing a 3.5"
> diameter, 48.125" tall solenoid coil wound with 21 gage wire at about 97%.
> The windings were coated with five layers of polyurethane and allowed to
> cure.  Today the outer jacket was assembled and filled with oil.  The outer
> jacket is a 4.5" OD PVC pipe sealed at the top and bottom.  The oil is
> transformer oil I purchased from a dealer on eBay last year.  I'm hoping the
> coil will be completely free of corona discharge.  Any other experiences
> with this type of coil would be of interest to me.
> 
> I plan to fire it up with the 25.25" flat spiral secondary on Thursday after
> all the glues, epoxies and polymers have a chance to cure.
> 
> Dave T.