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GNAT's meeting and spark gap ideas

Subject: 
        GNAT's meeting and spark gap ideas
  Date: 
        Fri, 21 Mar 1997 07:58:06 -0800
  From: 
        "David E. Sharpe" <sccr4us-at-erols-dot-com>
    To: 
        tesla-at-pupman-dot-com


Chip

Alex Tajnsek and I tried the no secondary test on a spark gap about
a week ago.  The basic circuit consisted of (1) 60:1 potential
transformer feeding a pair of 0.25 uF capacitors in series (0.125 uF
total capacitance) in parallel with the 1st HV xfmr, and a single
gap in parallel across the parallel combo of the xfmr and caps.
A secondary 60:1 potential xfmr was placed across the gap and the
LV sec. was loaded with a 1500 W lamp.  

We were attempting to determine losses across the gap.  The gap
was a pair of 2" OD X 3.5" long brass caps made for a oil filled
120/34.5 KV PT (4.5kVA) Alex acquired.  The input voltage was taken
up to 60VAC (Vo ==> 3.6kV).  The gap was firing disruptively, and
about 30V was seen across the 1500W load.

The brass gap was quenching nicely (even at 3000W input, NO BALLAST
USED).  This crude experiment line is extremely early, but the "heads-
up" suggests about 50% of the energy is swallowed by the gap!!!
Alex is going to build an extremely large (20-30KW) coil system
using the 34.5kV xfmrs.  The experimental design I am suggesting
to him is:
(1) Rebuild above system for MAX CURRENT THROUGH GAP.  The testing
    would determine active areas, materials and shapes necessary to
    quench currents up to ~ 2kA.  This would be done at relatively
    modest input voltages (<<15kV), and can be built quickly.
(2) Build a small Tesla Coil (2 coil classic), however slight twist.
    Will be rotary, and will have up to 70kV powering the system.
    Lots of primary turns and small capacitance.  Determination of
    wheel size, electrode shapes, series gaps per kV and general 
    construction techniques necessary to survive at 60-100kV.
(3) Build a new high power gap using what was learned in (1),(2) to
    build a radical new design (outside the envelope? what?-at-~#$^^!
    envelope), capable of up to 30kV, and power levels to 30kW.

Based on our quickie experiment, testing gaps under that mode would
have an enormous value to the community.  We intend to use the new
SSwattmeter for monitoring current flow through the system. The key
to this whole experimental venue, develop a new gap of total radical
design, and control capabilities over anything built in the past by
anyone.  Comments?

DAVE SHARPE, TCBOR

"THE DIFFICULT WE DO NOW, THE IMPOSSIBLE TAKES A LITTLE TIME!! "