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Re: [TCML] Tesla coil simple questions?



On 3/1/14 5:04 PM, jhowson4@xxxxxxxxxxx wrote:
Comments below



Thanks,
John "Jay" Howson IV


"Why thank you, I will be happy to take those electrons off your hands."

----- Original Message -----
From: "matty mcqueeney" <matty_queeney@xxxxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Monday, February 17, 2014 3:40:11 PM
Subject: [TCML] Tesla coil simple questions?



Hi, I am in
the middle off my dissertation (University project), I was wanting to get the
correct answers for the questions below:



The spark
gap equation..... L = 1.7 x /Power of Nst.

Why do we use 1.7?? I have tried looking for this but
could not find a reasonable answer.


Its essentially a curve fit parameter someone calculated some years ago. If i remember correctly the 1.7 parameter needs to be adjusted for the (smaller?) and larger coils. It has been pretty spot on for my medium sized coils.





Also



When
the voltage/ current has been supplied from the transformer.... the Capacitor
is charging, when it reached maximum the Spark gap ionized air and strikes
which makes it a closed circuit.



what
is happening to the Spark gap when the capacitor is charging? why does it
strike? how is the spark created?

The spark gap is an "Open" circuit. which breaks down and becomes essentially a "short" (not really but you can look up the electrical properties of an arc yourself) when a voltage threshold is surpassed.
The spark itself is initiated when the electric field in the gap (because of an increased voltage) becomes so great that the electrons in the air are ripped from the atoms, thus ionizing the air in that region or the electrons are leaking from the voltage source into the air. In either case, once the air is ionized and these electrons are free the region becomes significantly more conductive than it was previously, allowing for the charge stored in the capacitor to flow freely across the gap. which is basically now a "wire" of plasma.

There
are lots of simple ways of saying it, but id like to know what is actually
happening.



Bazelyan and Raizer, "Spark Discharge", CRC Press
http://www.amazon.com/Spark-Discharge-Eduard-M-Bazelyan/dp/0849328683

If you *really* want to know what's happening in a spark, this is the book to get. The Amazon reviews are unfairly low, in my opinion. Sure, the exposition isn't as good as Martin Uman's books on lightning, but this is probably the only book out there on the topic, and you'd be hard pressed to find the information in other places. (Besides, there's a >100 meter long spark picture in it!)

I note that the amazon price is higher than other sellers..
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