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Re: Thyratron pair (was DC Drive)





---------- Forwarded message ----------
Date: Sun, 12 Oct 1997 09:02:46 -0500 (CDT)
From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Thyratron pair (was DC Drive)

10/12/97

Bert wrote: 

snip

>After studying this circuit a bit more, it appears that a this may 
>alsobe a very good way to use a pair of thyratrons for performing 
>quenching experiments or for building an electronic disruptive coil. 
>With this circuit, a conducting thyratron should never see potentially 
>damaging voltage reversals because of the DC offsets. If we design the 
>circuit so that Vpeak of the thyratron is greater than 2xVin, and 
>design it in such a fashion that we ONLY alternately trigger T1 and 
>T2, the approach should work. By varying the trigger pulse width, 
>triggering on any notch could be controlled. It may even be possible 
>to "quench" at any primary current zero crossing. A pair of 4C35's 
>should be able to handle Vin of up to 4 KV, and a pair of 5C22's, up 
>to 8 KV.

snip

>                       
>                      T1
>                Anode   |
>     -----------------| | <------------  
>             |          |             |
>        +    |                        | 
>           -----                      | 
>       Vin -----                      |
>        -    |       Cp               |
>             |      | |      Lp       | 
>     ---------------| |----OOOOOOO----- 
>             |      | |               | 
>        +    |                        |
>           -----                      |
>       Vin -----                      |
>        -    |                        |
>             |          |             |
>     -----------------> | |------------
>                        |  Anode
>                      T2
>                 
>-- Bert H --
>
>

Excellent post.  This push-pull configuration has some of the aspects 
of Dave Sharp's new push-pull TC.  As we move away from the confinment 
of 60 Hz drivers our technology is elevated to a new plane. 

Since a thyratron is only on full blast after it is triggered, perhaps 
big, low impedance vacumm tubes (or IGBTs) might give better control 
than thyratrons.  As such, the primary driving waveform can be better 
tailored to the requirements of the resonator.  I do not refer to a 
continous wave vacuum tube driver, but disruptive vacuum tube pulses 
that have superimposed information content that the secondary resonator 
requires.  Fast pulse rise time and information content of the pulse 
are both crucial. 
 
The vacuum tube or IGBT is pulsed rapidly with superimposed information 
content required by the resonator, but for the most part is quiessent. 
Similar to a spark gap a in on-off time.  There is no coil feed back 
driving of the vacuum tube, it's totally electronically driven.  BTW, 
SGs contain these two requirements of fast rise time and much, much 
more irrelevant information content and energy that is wasted.  If the 
resonator cannot use parts of the wave content, then it simply ignors 
them.  The resonator simply chooses what it needs to resonate.

So, why not determine the requirements of a particular resonator and 
design our drivers to provide only these requirements?  We may be able 
to exprimentally provide even better waveform content than that which 
occurs naturally. 

Think about Dr. R's version of the extra coil where he has eliminated 
the driver secondary altogether and drives the extra coil from the 
primary alone.  The reason this works is that there is fast rise time 
and the the required extra coil wave content is available.

As we become more familiar with these driving techniques, we will 
eventually be able to elminate the primary/secondary driver altogether 
and directly drive the resonator electronically.  


RWW