Character Revisited

To: tesla-at-pupman-dot-com
Subject: Character Revisited
From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
Date: Mon, 25 Nov 1996 10:31:06 -0800
11/25/96

R. Hull recently posted an excellent post comparing the character of TC 
discharge arcs with different drivers.

As a follow up, I forward a portion of a post from a nonlist member.
 
     I had ment to make clear, that if you could drive a TC with a      
     class A solid state, or vacume tube driver, and a signal with the  
     same frequancy components as a spark gap, you would see the same   
     arc lenghts per primary power levels as you would get with a gap.
     
     I think it's not the gap, but the frequancy content that makes     
     gaps appear to deliver longer secondary arcs for a given power     
     level.  Unless the frequancy components of the primary current are 
     the same for the tube or transistor driver, we cannot make diurect 
     comparisons to gap driven coils.
     
     I've used some fancy soild state drivers with the same coils that  
     have been driven with gaps, and while I cannot claim to have       
     proven this exaustivly, it seems that gap vs. tube or transistor   
     makes no differance.  A clean primary current (spectrally pure     
     that is) is less 'efficient' (as measured by secondary arc lenght) 
     than the mess from a gap.
     
     To do this, I digitized an actual gap with a HP arbitrary waveform 
     recorder/generator, and fed this through Phase Linear DC to 100    
     Khz amplifiers.  A RF wattmeter was used to adjust the gain of the 
     Phase Linear amps (two bridged together) so that the primary       
     current was as close to that measured (by the same watt meter)     
     when the coil was driven with the gap.
     
     Guess what, same arc lenght.  Alter the frequancy components of    
     the waveform, and the arc lenght appears to change at a faster     
     rate than when the power levels alone are changed.  So I agree     
     that the arc is important, but why the arc is important may have   
     more to do with the frequancy profile of the primary current than  
     it depends on what kind of driver is used.
     
     I claim that if you deliver the same primary current waveform with 
     a tube or transistor as is delivered with a gap, you get identical 
     performance with each driver.

     snip . . .

     Getting back to the gap vs. tube or transistor discussion, in my   
     mind it all boils down to what is inside the wave, it's internal   
     structure and frequancy/phase profiles.  If we extend frequancy    
     and phase to the pure potnetial waves, then scalar and EM really   
     are the same things.


Has anyone run a spectral analysis on a spark gap discharge?  It may be 
informative to alter the spectrum or perhaps delete or add spectral 
components in order to enhance TC preformance.  Take heart Alan Sharpe.

RWW