Re: Streamer loading effect

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

Original poster: "Wells Campbell by way of Terry Fritz <twftesla-at-qwest-dot-net>" <wellscampbell-at-onebox-dot-com>




Barton B. Anderson wrote, 

> 
> Hi Wells,
> 
> Some of the TSSP measurements a while back took a look at detuning.
> It
> seems several coils achieved their
> best spark length when the coil was detuned (more L). From memory,
> I think
> the average detuning was in the
> range of 7 to 10%. My coil ended up something like 13% for longest
> spark
> length which also happened to have
> the least number of streamers at any given time. I would bet many of
> our
> coils which are tuned for longest
> spark length are detuned an amount equal to offsetting the capacitive
> streamer loading as compared to a
> coils "sparkless" measurements (even if not realized).


Ah, this fits with my theory: even these coils which are "detuned" 10-13
percent reach a point at which further detuning on the low frequency
side prohibits any streamer formation at all (if they are tuned before
turning on), obviously because the harmonic oscillations that permit
the energy transfer can no longer occur at the outset, and no streamer
can be formed at all. However, if the coil was given an additional 10-20
percent detune  after the streamers were already established and as the
coils were running, would they grow more? would the arc channel that
had been established by the already formed fully loaded streamer serve
as existing topload permit even more "detuning"? Could this "growing"
continue to maybe double or triple the streamert length before it went
out and a new one had to be formed?

 See, I think that it is the streamers themselves that are doing the
detuning by adding effective topload as they form, and lowering the tank
frequency while running will be keeping the coil in tune, permitting
longer and longer streamers to be grown as the coil runs.

 Think of how "pulling" an arc works. Take one lead fom a NST and bring
it close to the other until an arc forms, then slowly pull it away. The
arc can't form at all until the initial condition is satisfied, that
is the leads are close enough for the air to break down. Once the arc
has been established, however, the lead can be pulled away to multiples
of the initial distance. Try turning on the NST at max distance, and
nothing. 

Now, I am not suggesting that the streamers work just like jacob's ladders
arcs, but I think that lowering tank frequency as the coil runs could
be roughly analogous to opening the gap in a jacobs ladder, lengthening
the arc once it has formed, and permitting the system to operate well
past the point at which initial conditions permit it to operate.  I realise
that streamers essentially go out and re-form every time there is a spark
gap firing, but I think that there is some very favorable conditions
set up for the next bang, probably in the form of hot and ionized air.
if there wasn't, streamers would form at random each bang, creating a
strobe effect all over the place (kinda like lower power, lower BPS systems)
. As it is, they pretty much form where the last one left off, with some
small variations, which makes them writhe and wave in that way we like
so much. 

you mentioned that at the lowest "detune" there seemed to be fewer, longer
streamers... I think this is evidence that the streamers are shaped to
match the required topload... imagine a toroid with one large streamer
projecting from it, say three feet. Now compare that with twelve small
streamers, each three inches long, from the same toroid. the first case,
it seems to me, would have a greater effective capacitance, thus a lower
resonant frequency. The streamers have evolved to fit the appropriate
conditions. 

OK, my head is about to pop, but let me just explain my "fantasy coil"
and how I plan to get there...

1) real-time adjustable primary inductance:
Easy, and fairly lo-tek. Two turns of refrig. tubing, in a cylinder,
 with three smaller turns that fit inside. The smaller turns run in opposite
direction as the larger, and cancel the inductance when inserted. This
arrangement is an off axis tuning arrangement, and will be connected
in series with the primary coil. detuning will happen as the small coil
is removed from the larger, adding L.

2) high BPS
I think that the greater the BPS, the greater the tendency of the new
streamer forming in the path of the old can happen, by nature of there
being less time for the conditions to deteriorate. Look at the solid
state systems, and their one sword-shaped streamer. So what loves high
BPS? a DC maggie with an async rotary. All I have left to do is build
a power controller and the off-axis tuning coil. 

Operation would go as follows: Turn the coil on, let the usual streamers
form, then slowly add primary L. The streamers should lengthen, snaking
outwards. This would continue until they would happen to go out, at which
 point the system would be out of tune, and no new ones would form. The
tuning would have to be reset, to start the process again. Adding power
while the streamer grew couldn't hurt. Imagine growing a streamer straight
up via breakout point, six to ten times the lenght of the secondary,
before it collapsed and had to be started anew. Artful operators with
one hand on the tuner and the other on the variac could break world's
records...
 
Alright, enough. Feel free to poke holes in theory, as it is just that
at this point. 

Cheers, 

Wells