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Re: Thyratron pair (was DC Drive)





---------- Forwarded message ----------
Date: Wed, 15 Oct 1997 00:09:40 -0400 (EDT)
From: richard hull <rhull-at-richmond.infi-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Thyratron pair (was DC Drive)


>>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
>
>Richard Wall is correct in the above by my observations to date.  You can
definitely quench too fast even at k=.66!!!  Spark gaps appear way too slow
and H2 Thyratrons appear a bit fast.  Faster is better than slower if you
are building a very tightly coupled, small table top maggey system with a
natural higher frequency than the big jobs.  I don't think an H2 thyratron
could compete with series quench rotaries in k=.45 coupled maggeys of 100khz
or lower frequencies in the 10KW power class.  (they are just too quick)

Richard Hull, TCBOR
>