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Re: Terry's DRSSTC - Experiment - A curious thing...

Original poster: Steve Ward <steve.ward@xxxxxxxxx>


Comments within:

On 4/12/05, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
> Hi All,
> I tried my experiment and found something very odd!!
> I was running small streamers (~8 inches) here in the basement off a sharp
> tip on the terminal.
> The 1, 2, 3... pulse thing did not seem too interesting.  After about 5 to
> 10 pulse the streamers seem to reach a maximum level.  After that they just
> last longer but their length does not increase....

This has been found to be true not only when running the coil in
"burst" mode (several pulses per firing with a long rest inbetween)
but also true of increasing the length of each burst in themselves.
The plasma just gets fatter, not longer.

> But one thing that certainly did get my attention was this.
> After about 400 BPS and certainly from 600 - 1000 BPS the streamer length
> "cyclically" goes from a small brushy discharge to a long single streamer
> as a function of BPS.  Sort of like this:

I used to run my DRSSTC-3 in this "burst" mode you are using now.  I
would run the BPS up to 500 or so, and then gate that signal at a few
Hz.  The streamers DID get longer, but nothing that exciting really,
maybe 10% growth.

> 500BPS = short sparks
> 550BPS = long single arc
> 600 BPS = short sparks
> 700 BPS = long single arc
> .
> .
> .
> Those are not really the exact numbers, but just increasing the BPS say
> from 660 to 690 increased the length of the streamers about 5X!!

I did notice that at very low powers, the growth was much more
exaggerated.  My coil will go from spitting corona to forming nice
streamers (probably 4X as long as the corona) when you really stomp on
the BPS!

> increasing the BPS further to 720 made the streamers fall back to the short
> discharge again!

Very strange!

  It is almost like the streamer length is going through
> nodes and anti-nodes as the BPS is increased.

Perhaps we could write 2 equations to describe this action and see how
they interact.  Maybe when you hit a given firing length of time the
streamer growth is not optimal, but on the other hand, the BPS might
over come that and optimize it again.  This probably doesnt make sense
to anyone :-).

> I don't "think" it is anything in the electronics.  There is nothing to
> really cause it on the controller side.  I just used 20 pulses all the time
> at fixed pulse width (35mS)

Do you mean 35uS?  Or is this width the time between each group of firings?

 so the total power is pretty much the
> same.

Well... the ENERGY is the same, but you are delivering it in a shorter
amount of time, so power is greater at higher bps.  Or have i got
something wrong?

  Only the BPS rate of the 20 pulse bursts was changed.


> I was wondering if the L and C of the streamer was resonating or
> something.  But I could not imagine how that could be...  It certainly did
> seem like the long streamers "go in and out of tune"....  You could adjust
> the BPS to maximize the length....

Hehe, gotta watch the IGBT heating then!  My coil made some wild
noises when running like this.  I could even tune my 2 oscillators to
play musical 5ths, 3rds, octaves etc... it really WAS singing ;-).

> If it is a real repeatable effect, it may have been easily lost in a
> conventional spark gap type coil's erratic operation.  The DRSSTC with
> computer control can easily pick out this effect.  I can change the BPS
> from like 700BPS to 701BPS without changing any things else and run like
> that for hours!  It is really strange running coils by computer!!  But the
> level of control and repeatability is astounding!!

Perhaps my next project should be to take an old junker PC and make it
into a DRSSTC controller!

> So curious if anyone has ever noticed streamer length dramatically coming
> and going buy changing BPS a little at the above 600BPS level?

I havent gone above 600bps.  Like i said, at low power the differences
were dramatic, but i didnt get too much gain in spark length when it
was maxed out on buss voltage.  This *might* change at more than
600bps so cant verify it.  My buss caps often sagged from this kind of
use and would result in shorter sparks.  This is where it really
helped to "gate" the interrupter to just send out 10 shots at a time
or something.

Writing this email i see we should really start defining terms like
"burst" "firing" "shot" etc... i think that *you* will know what i
mean, but other people probably wont.  Care to make a set of
definitions or should i?


> Cheers,
>         Terry