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Re: 100 meter sparks





---------- Forwarded message ----------
Date: Wed, 22 Oct 1997 10:47:16 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: 100 meter sparks 

Hello All,
           I have an observation to make on this post that *does* 
relate to Tesla Coils (note to moderator ;).

From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: 100 meter sparks

> Hi All,
>      There is a new book out from the CRC press
> by Raizer et all called the "SPARK DISCHARGE".
> There is a picture of the Russian 100+ meter spark
> in the first chapter.  It is beyond awsome!  The Marx
> generator tower must be 500 feet high!  The book is
> very hard core theoretical - the good stuff - on the
> processes involved in the initial streamer and subsequent
> spark formation only.  It contains a lot of useful constants.

> That must be the 7.2 MV marx generator referred to in Fruengel's
> book. Must be quite impressive. Was the spark in free space or was
> it along an initiating wire? What is the ISBN of the book, or where
> is it available?

I had a think about this. 7.5MV (DC essentially) = 300+ feet????  And 
according to lumped calcs our TCs are struggling to get to 1MV in the 
medium power range yet throw sparks (repetitively I hasten to add) at 
least up to 9.5 feet at this voltage (if the X-ray measurements of DR 
R are correct).  Now, we know that TCs throw sparks far longer in 
repetitive mode than single shot but the voltages as far as the 
terminal go are no higher than single shot (for very good reasons). 
We also know there are very good reasons why the sparks actively 
reach a lot further in TC repetitive operation. 
      Elsewhere we read that Tesla was generating (supposedly) 10MV+ 
yet his machine was throwing sparks a mere, perhaps, 50 feet or so
point to point *****in repetitive operation****. Does anyone else see 
a serious discrepancy between these observations and figures?
      A lot of my observation of length vs single shot voltage in 
TCs is based on the Marx banks I built and use for comparison. There 
is a very definite upper limit on the voltage a Marx bank can produce 
because it does not incorporate resonant artifacts. I may have more 
on this after a five day break as I am planning to stack the two 
banks together to up the output.

Malcolm