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Re: Magnetic Spark Gap...

I used the existing frame of my old single air-blast gap (minus
air) with two poly insulatated rare-earth permanent magnets
mounted in between. The magnets were strong enough to remain
suspended across the gap when carefully positioned on synthetic
line (plastic string, cord, etc.). This gap demonstrated the
ability of a mag field to quench, but also illuminated a number
of design difficulties.

Quoting "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>:

> Would you be able to describe the gap more exactly please 
> (perhaps with the aid of a diagram (yeah I know ASCII art's a 
> dog but better than nix)? 

I can do even better. The scale diagram for this particular gap
is archived at the  nic.funet.fi  ftp-site in the file
sparkgap.zip. I will upload the GIF image (very small file) to
the group so you can get an idea of where I started from. This 
basic gap is very versatile; it has served admirably as a simple
static gap (no air, no mag field), an air-blast gap (super
performance with neons), a test platform working with simple
magnetic quenching by mounting permanent magnets on either side
of the gap, and as a nice looking adjustable safety gap when a
ground plate is mounted between the hot electrodes. With a
properly designed base, this gap will serve interchangeably in
any one of the above applications and will only require a few
minutes of time in the conversion.

> Also, an elaboration of the difficulties you encountered
> would be highly valuable. 

The two major difficulties included heat and the presence 
of a conductor in the gap. To prevent the arc from shorting 
the gap by jumping to the conductive magnets, I wrapped the
magnets in softened polyethylene to act as an insulator. This
worked pretty well for a short period of time, but then the hot
plasma began to carbonize the plastic, and a conductor (carbon)
was again present in the gap. Of course after the arc had played
on the magnets for a second or two the heat build-up in the
magnet causes the field strength to fall off. 


Richard Quick


... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12