Re: VTTC/SSTC Spark Appearance Comparison

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

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 08:23 01/04/03 -0700, you wrote:
>Original poster: "Justin Hays by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><pyrotrons2000-at-yahoo-dot-com>
>
>
>On this page, notice the VTTC arcs that are *perfectly straight*. I
>see a couple of teeny tiny branches at the ends of two of the longest
>arcs, but for all practical purposes the arcs are 100% straight w/ no
>branching. These are referred to as "sword-looking" I believe.

THat is one cool picture



>So my question is, why are VTTC arcs perfectly straight, and SSTC
>arcs not?

Mmm, tricky question! Steve Ward seems to have written a bit about the 
subject on his site. I think (this is just my opinion) the frequency is 
important. VTTCs usually end up running a higher frequency than SSTCs 
because switching losses aren't a problem. But I have seen VTTCs that 
produce very branched discharges, especially the one made by Ross 
Overstreet. There is a cool movie somewhere that shows this coil 
overheating and burning out. It would be interesting to see what frequency 
it ran at.

Since you have a feedback SSTC, when you remove the topload, it increases 
the frequency you're running at. That ties in with the theory.

Another possibility is that it might be the gradient of the electric field. 
Streamers always form where the gradient is steepest. If you have a big 
topload in place, the gradient will be more uniform, and the streamers may 
have more trouble making their minds up which way to grow... Steve Ward's 
VTTC (like most VTTCs) has a tiny topload with a great big breakout point 
on top. Ross-O's rig had a much bigger toroid. That's what I think anyway.

Steve C.