Re: static gap were run in series with a rotary gap

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 1/18/04 8:55:09 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

>Has any one got input on this?
>I was wondering if a short static gap were run in series with a rotary gap
>would it help timing?
>That's not exactly what I mean let me explain.
>
>As the rotary brings the electrode near each other they might let an arc go
>a little before they are in line because of the high voltage present might
>jump the arc.  Because the air in the area is moving this distance might be
>somewhat erratic and thus cause the gap to fire sooner or later.
>
>If a small static gap were ran in series the distance of the total of the
>gaps would be a little larger.  This might reduce the arcs from jumping to
>the electrodes in the rotary gap before the electrodes are in line.  And
>the electrodes in the rotary could still be kept very close to allow for a
>more precise timing.


Luke,

Generally the timing is not that important.  I'm not sure how much
a series static gap would help the timing precision, it may.  In some
cases, such as when using a small diameter rotary rotor and
slow turning motor at 120 bps, the timing *can* become critical.
In one test I used a 3" rotor with an 1800 rpm motor and obtained
somewhat erratic spark behaviour.  I had analyzed the situation
in more depth at the time, but I don't remember all the details,
but I have it in my notes, and I posted it on the Tesla list a year
or two ago.  It's probably only a concern with small NST powered
systems, where the inductive kick charging is sensitive to timing
errors.  It's important to note also that small coils often
can barely fire across the rotary gap spacing, and may have
trouble firing smoothly if a few static gaps are added.  Very
narrow static gaps should work OK.  Higher voltages will give
less trouble with this also.  Generally the easiest way to solve
timing issues is to use a faster rotary of larger diameter.

Series static gaps are often used with rotaries, but they are used
to improve the quenching (to make the spark quench faster).
Fast quenching is helpful because it traps all the energy in
the secondary without letting some of the energy making
further round trip transfers back to the primary, then back
to the secondary again, etc.  Extra gaps increase the gap
losses somewhat, so there's a tradeoff situation.  There is
a lot about this in the archives also.  Some have suggested
that the energy round-trips may actually be helpful for spark
growth.  There are still unknowns in this area.

John