some new ideas for the SSTC guys

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


Problem --- Exploding IGBTs when they are hit with a sec - pri spark (Terry 
Blake's coil terrible demise at our Teslathon).

A few years ago I did some experiments with a flat spiral coil (18 dia. 
sec.).  In the classic configuration with a .05 uF cap, RSG, and 4.5 turn 
primary the sec sprayed out 8 ft long sparks.

At the urging of a plasma physics guru from UW-Madison (Paul Nonn for those 
of you who might remember meeting him at Ed's recent Teslathon), I removed 
the sec coil and placed it on a stand 10 feet away.  I used a 7 inch corona 
ball on the bottom to prevent any corona and used a single tap which I 
attached to the "normal" primary coil.  With some re-tuning it was again 
spraying out 8 ft sparks.

What I'm getting at here, is, the SSTC experimenters, Dan M., Steve W., 
etc, might try using a larger dia sec coil and then use a 15-20 turn test 
primary coil while feeding the sec coil a few feet away.  If this works, 
then the greatest danger to SSTCing, ie, blowing the IGBTs should become a 
problem of the past.

It will take some experimenting --- perhaps the best tap is "inside" the 
normal classic tap location or perhaps it will be "outside", but either 
way, getting the sec away from the primary to act as a series fed setup 
should eliminate the IGBT explosion problem.  If it does work the primary 
can be either a flat spiral or normal solenoid coil --- perhaps enclosed in 
clear acrylic with a large "feeder" wire over to the sec coil.

If someone DRSSTC tinkering wants to experiment with this idea on their 
present or planned near future coil, please advise and I will send you a 
nice 10 ft long chunk of #6 AWG for experiments --- with 125 kV BIL 
insulation --- it's 1 inch thick and offers great HV feedwire 
performance.  We use this "big Red" on all our HV power supplies to feed 
the 14.4 kV HV over to the base of the oscillator.

Might work, might not, but worth trying.

Dr. Resonance