Re: 20 joules at 100 bps vs 4 joules at 500 bps - any difference?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FutureT@xxxxxxx 

In a message dated 7/15/05 3:22:11 PM Eastern Daylight Time, 
tesla@xxxxxxxxxx writes:


> now i have a new question - what maximum bps do we need for bright
> streamers and not too low efficiency at the same time? something about
> 200-300 bps? because as John Freau said before:


One thing to consider is that a larger coil will produce brighter
sparks in general.  So a large coil running at 120 bps produces
rather bright streamers.  And of course they'll brighten up a lot
when they hit a ground.  Personally I'm satisfied with the
brightness of 120 bps sparks even on small coils.  These
sparks look impressive in a dark room.  But yes, I think
200 to 300 bps is plenty high enough to give good brightness to
the streamers.   Regarding the
higher bps sparks, they can sometimes form a sort of
thick tendril that fans at the end.  This can look impressive
too.  I also don't like it much when disruptive sparks look
too much like tube coil sparks.  Bill Wysock likes to run
at 240 bps syncronous for some of this coils, and this
breakrate gives a nice penetrating sound and good streamers.
DC Cox often runs at about 180 bps non-synchronous I think.
His coil's sparks are very good too.

The 120 bps sparks have a sort of slower floating motion
to them which I like also.  I mean compared to 400 bps or
higher breakrates.

In some cases when folks saw impressive
spark length gains as they raised their bps, it may have
been because their toroid was too large to begin with
for the bang size, or something like that.  In my tests
i also tried various toroid sizes to try to account for those
possibilities.  One factor that is interesting is the concept
of coalescence of the streamer.  Some coils tend to
produce a bunch of small short streamers until a certain
bps is reached, then the sparks coalesce into a single
streamer as the bps is raised.  Greg Leyh's original large
coil behaved this way.  First the sparks coalesced at
some particular break rate.  Then the spark length increased
linearly as the breakrate was increased.  The bang size
was kept constant at all times.  He saw the longest sparks
at about 300 bps.  Maybe if he had a larger bang size,
this behaviour would have disappeared.  I never saw this linear
increase in break rate in my own (smaller) coils.

Cheers,
John