Re: Output arc lenghts (fwd)

---------- Forwarded message ----------
Date: Tue, 21 Jul 1998 17:05:50 -0700
From: Ed Phillips <evp-at-pacbell-dot-net>
Reply-To: ed-at-alumni.caltech.edu
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Output arc lenghts (fwd)

"I thought a static gap tied the firing rate to the AC
mains cycle (100pps for 50Hz, 120pps for 60Hz)."

	The line frequency certainly influences the spark rate, but other
factors do do.  For instance, if you have a small capacitor and close
gap spacing you will get many (small) sparks per half cycle.  As you
increase the capacitance and approach series resonance (with the NST
secondary inductance, if you are using an NST) the spark rate will
increase, but go down again if you open the gap some.  Under some
conditions it is even possible to get a spark rate of a fraction
(1/2,1/3, etc. of the line frequency), or even semi-chaotic firing with
no single sparking frequency.  Of course, if you open your gap up enough
and you are near series resonance by increasing the capacitance
(so-called, somewhat in error, the "matched" capacitance), your spark
rate will go to zero as the transformer secondary shorts!