Set up outside again

 * Carbons Sent to: usa-tesla-at-usa-dot-net

Quoting Esondrmn-at-aol-dot-com (Ed Sonderman)

> Did you ever get this message?  

I am sorry. I have really been swamped... 

> I am still getting loud pops coming from the rotary.  My 
> controls are located about 30 feet from the coil and you can 
> easily hear these pops over the noise of the secondary 
> discharges.  I don't know how else to describe them and I sure
> would like to get rid of them.  It doesn't sound healthy.  They
> occur maybe one or two every couple of seconds. Is this maybe 
> some kind of kickback problem?

It sounds like kickback to me. Do the safety gaps fire at the
same time? I have thought about this before, but never was able
to figure out what might be happening. What about Mark Graalman's
suggestion that it might be resonance in the control and supply
circuits? I think he mentioned either changing the value of the
RF choke inductance or placing resistance in the HV feed to the
tank circuit to elminate/reduce the possibility of 60 cycle
resonance in the control/HV feed. Thoughts anyone?

> Then I took the wire off the top of the toroid and fired the 
> coil up again - still at 7 kva.  Running outside is different 
> than running in the basement. The wind actually blows the 
> discharge breakout point around on the toroid. That looks cool. 

I will mention that the wind also bumps your resonate frequency
up and down because you no longer have a steady state ion cloud.
When the wind blows the frequency rises, when the winds stops
blowing the frequency drops. Interesting huh?

> I had only been running maybe 15 to 20 seconds and all of a 
> sudden I got a massive discharge from the top of the secondary
> (under the toroid) to the primary strike rail.  I immediately 
> shut the power down.  I tried to refire it and got the same
> thing.  I inspected the top of the secondary and did not see 
> any damage.  Guessing that I now had the toroid too high, I 
> changed back to the shorter spacer that I had been running with
> in the basement.  It is 2" shorter, the toroid is now 9.0" 
> above the top of the secondary.  I fired it again and 
> everything was ok for a short while, I was still getting 
> strikes from the toroid to the primary strike shield, not
> continuous but often.  All of a sudden a massive bolt broke out
> from the center of the secondary to the primary strike shield. 
> I turned the power off and refired it.  It is difficult to get
> it to run without breakouts happening from the coil itself.  I
> even had the safety gap fire once. 

If this occured when there was a lot of wind I would not be
surprised. Still air allows an ion cloud to build around the
toroid, the wind blows the ions away. The effect is that you get
substantial frequency changes in very short periods of times. It
messes a bunch of things up.

Possible solutions:

Load a smaller toroid on top of your large toriod. This will
reduce the size of the ion cloud, and should assist breakouts
from the upper end (top) of the system rather than the lower end.

Try placing extended ridges on the outside of the toroid surface
to disrupt the field shape. I have seen Richard Hull do this with
success, and it has worked well for me. Cut a soda can into a
couple of 1-1/2 inch wide strips. Bend the strips to form a
gentle arch, then tape a couple of these strips to the outer
most edge of the toroid. The strips of AL should form a "bump" on
the outer edge of the toroid so that it promotes a spark breakout
from this point without really substantially reducing the peak
voltage required to break down the field. 

It seems that what is happening is that the radius of curvature
on the secondary coil is much smaller than the radius of
curvature on the toroid; with the voltages so high, the system
breaks down from the smaller radius (coil) rather than the larger
radius (toroid). The possible solution above introduces a point
(or two) on the toroid that has a smaller radius of curvature
than the secondary coil, thus promoting breakdown from the toroid 
rather than from the coil.

> With a smooth toroid now the discharges want to break out
> from the secondary coil itself. 

Exactly what I am talking about above. The toroid has a greater
radius of curvature and the voltages are extreme, so the charge
density that ends up on the six inch diameter coil (remember
these fields have multi-megawatts of peak power) is sufficent to
break down into spark. By using the metal strips to force a small
imperfection in the toroid shape you should be able to force the
breakout back to the toroid instead of from the smaller diameter
secondary coil.

Problems like this are typical of systems where you have pushed
the design limits right to the edges. With some fiddling you will
get it all straigtened out.

Richard Quick

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