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"vacuum" gaps

Hello Matt,

> ..... going to a vacuum gap in series,
> ..... I recommend them highly.
> Scott Myers

> When you say vacuum gap, what exactly do you mean.  Is this a gap in an
> air tight container with all the air sucked out or is this some type of
> cooling technique.  I was under the impression that sparks create
> x-rays when created in the presence of a vacuum.  If this is what it
> is, what type of shielding do you use?  At one time I was thinking
> about implimenting a gap surrounded by a vacuum, but abandoned it as
> too dangerous.  Thanks alot.

It is a cooling/quenching technique.  My "vacuum" gaps could be more properly
called "vacuum cleaner motor" gaps.  I build several gaps into one side of a
plastic box.  I install a vacuum cleaner motor in another side.  The results
are that when the motor is turned on air rushes into the box between the gaps.
It is a fairly simple system that gives excellent quenching.  It is small,
cheap to build and self contained, except for the power cord.  My units are
under 12" cubed in total size.  If a good vacuum cleaner motor is used,
quenching can be acheived that rivals an air blast gap.  I have successfully
used one alone with a pole transformer, without a rotary for decent performance.
(A rotary should still be used to achieve optimum performance with a pole
transformer or other externally ballasted transformer.)

I have oversimplified the "gaps in the side of the box" description here.  There
is a little more to it to keep the ends of the gaps from carborizing and ruining
the quenching.  Where the ends of the gaps (short sections of hard copper pipe)
meet, they must not touch any surface.  If it does, the gaps will immediately
carborize that surface and ruin the quenching.  Either stand the electodes off of
their mounting surface a bit or slot the mounting surface where the electrodes
meet.  This will keep the carborizing from occurring and keep air rushing past the
ends.

If you want to build one, get the hardest pulling vacuum motor you can get.  A
motor from a Tri-Star or Rainbow sweeper work well.  A standard canister vacuum
cleaner motor will well also, it just pulls a little less air.  Shop-vac motors can
be used, but they turn at twice the RPM's and scream quite loudly.  They pull
about the same amount of air as a standard canister vacuum cleaner.  I get mine
from a local Rainbow dealer who takes "trade-ins".  I select a vacuum cleaner
from the pile that still works and gut it when I get home.  The motors tend to be
in poor shape, but if I get a couple of months from it, I've done well and it cost
me nothing but a little time.  One nice thing about these canister vacuum cleaner
motors is that most of them use a standard bolt circle and pilot diameter for
mounting.  I have been told that just a couple of companies build practically all
the vacuum cleaner motors for everyone.  That is why the mounting pattern is a
common one.

Scott Myers