Re: Thyratron pair (was DC Drive)

To: tesla-at-pupman-dot-com
Subject: Re: Thyratron pair (was DC Drive)
From: Tesla List <mod1-at-pupman-dot-com>
Date: Mon, 13 Oct 1997 21:12:27 -0600 (MDT)
Approved: mod1-at-poodle.pupman-dot-com

---------- Forwarded message ----------
Date: Mon, 13 Oct 1997 21:14:33 -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)    

Malcolm wrote: 

snip

>> I specified in my post that the driver is not continuous wave, but 
>> fast rising pulses with information content (read harmonics) and 
>> relatively long periods of quiessence between pulses.  The vacuum 
>> tubes or IGBTs are driven electronically and not by feed back from 
>> the resonator.
>
>The pulse can only rise as fast as the LpCp surge impedance can allow 
>it to can't it?
>
>Malcolm

No, fast pulse rise time is basically related to switch turn on time.  
Spark Gaps and H2 Thyratrons turn on in a few nanoseconds, some newer 
fast tubes in the 10's of nS, IGBTs in the low 100s nS and older vacuum 
tubes much slower.  Secondarily, low surge impedance may slow rise time 
a bit, but fast switch turn on time is most important.

The faster the rise time the more the wave form resembles a square wave 
and there are multiple odd harmonics available for the resonator to 
use.  There is a danger in having too fast of a rise time with a very 
narrow pulse as the resonator is unable to use the fequency content of 
the pulse.

So, while rapid rise time is important, driver dwell time and frequency 
content during on time are also important considerations.  Frequency 
content of the driving pulse that matches frequency requirements of the 
resonator is crucial and probably represents a great deal of energy 
transfer to the resonator. 

RWW