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Re: Flat Spiral Tesla Coils




From: 	Bert Pool[SMTP:bertpool-at-flash-dot-net]
Sent: 	Tuesday, July 01, 1997 6:06 PM
To: 	Tesla List
Subject: 	Re: Flat Spiral Tesla Coils

> 
> From: 	Richard Wayne Wall[SMTP:rwall-at-ix-dot-netcom-dot-com]
> Sent: 	Monday, June 30, 1997 5:46 PM
> To: 	Tesla List
> Subject: 	Flat Spiral Tesla Coils
> 
> 6/30/97
> 
> Nikola Tesla in the June issue of the 1919 Electrical Experimenter 
> wrote the fifth article in a series called "My Inventions".  In this 
> article he states that his laboratory was destroyed by fire in 1995.  
> 
> NT wrote, " .   .   .   .  This calamity set me back in many ways and 
> most of that year had to be devoted to planning and reconstruction.  
> However, as soon as circumstances  permitted, I returned to the task.  
> Although I knew that higher electro-motive forces were attainable with 
> apparatus of larger dimensions, I had an instinctive perception that 
> the object could be accomplished by the proper design of a 
> comparatively small and compact transformer.  In carrying on the tests 
> with a secondary in the form of a flat spiral, as illustrated in my 
> patents, the absence of streamers surprised me and it was not long 
> before I discovered  that this was due to the position of the turns and 
> their mutual action.  Profiting from this observation I resorted to the 
> use of a high tension conductor with turns of considerable diameter 
> sufficiently separate to keep down the distributed capacity, while at 
> the same time preventing undue accumulation of the charge at any point  
> The application of this principle enabled me to produce pressures of 
> 4,000,000 volts which was about the limit obtainable in  my new lab
> oratory at Houston Street as the discharges extended through a distance 
> of 16 feet.  A photograph of this transmitter was published in the 
> Electrical Review of November, 1998.  .   .   .  "   
> 
> Tesla goes on to say that he had to go out in the open and this 
> ultimately was why he went to Colorado Spring in 1999 where he remained 
> for more than one year. 
> 
> Recently, others on this list have had NT's same experience of very 
> unimpressive flat spiral discharges.  Tesla nailed the problem of high 
> interturn distributed capacitance and seems to have corrected it with 
> spaced windings and high tension conductors.  I'm not sure he could 
> accurately measure a 4,000,000 volt discharge, but he could probably 
> quite accurately measure a 16 foot discharge.  To wit, our TC 
> measurement technologies have not changed that much in a century.
> 
> None the less, Tesla was quite successful in design and function of his 
> flat spiral geometries which were far more compact than his helical 
> coils.  To that end, perhaps we should investigate the various 
> parameters of flat spiral secondaries such as distributed capacities 
> and inductances as we do in the helical varieties.  After 
> "conventional" flat spiral secondaries are re-researched, a logical 
> extension would advance to "magnifier" spiral secondaries.  And, 
> ultimately flat spirals in liquid N2.
> 
>RWW

And it is for similar future experiments that I have 
acquired a 40 liter dewar flask for storing a large quantity of 
liquid N2!  My first low temperature tests will be with a 
conventional "extra" coil, but I too am fascinated with the 
possibilities of large flat spiral secondaries.  It will be far 
easier to insulate and immerse a small extra coil like Richard Hull's 
"E" coil (approx. 4 inch by 12 inch) than a flat spiral.

Bert Pool
bertpool-at-flash-dot-net