Re: Top load smoothness matters

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 5/20/03 7:39:20 PM Eastern Daylight Time, 
tesla-at-pupman-dot-com writes:

Chris,

Here's what I and others have found from doing various comparison tests.

Multiple streamers occur because the "bang-size" being
applied to the toroid results in a voltage which is much higher than
the toroid's hold-off voltage.  For example, if you use a considerably
larger toroid on your coil, then you'll get only one streamer despite
the lines in the toroid surface.  The break-rate is a big factor also.
Low break-rates require a larger toroid to obtain only one streamer
(for a given power input).

In general however, a much longer spark can be obtained from a
somewhat small spun toroid than from a corregated toroid.  For example
my old research coil gave 42" sparks using a 5" x 20" corregated toroid,
but a 2nd streamer tended to form.  With the 4.3" x 17" corregated toroid,
the 2nd streamer always formed.   When the second streamer formed,
it tended to shorten the spark output.  But using the 4" x 13" spun toroid,
I got one only streamer, 42" long.  It would be impossible to obtain 42"
sparks using a 4" x 13" corregated toroid.  My 4" x 13" spun toroid is not
polished, it has lines.  Even a corregated toroid will give long sparks and a
single streamer if the toroid is large enough.  Using a spun toroid (or any 
type
of smooth toroid), permits the coil to be more compact for a given spark
length and break-rate.

The bottom line is that the toroid size should be matched to the
break-rate and bang-size to give the desired spark effect.

The fact that you get extra streamers from a spun toroid even when
using a breakout point is a sign that the toroid may be somewhat
small for the coil.  (Depending on what type of spark effect is
desired of course.  Some folks prefer multiple shorter streamers.)

John


>Is this to say that a spun aluminium toroid would require wet and dry
>sanding to a near perfect surface?  My spun toroid has small lines
>around it and I get many simultaneous streamers, even with a break out
>point there will be several over shorter streamers.
>
>Cheers, Chris (NZ)
>