RE: [TCML] Spark gaps (again)

["Jim Mora" <wavetuner@xxxxxxxxx>]

Hi Deano,

I disagree with the scenario of blowing away the heated ions/air in multi
segment verses a single air blast. Take the CFPM of say an air compressor or
large leaf blower through a well designed nozzle (jet) and the resulting
concentration and pressure verses a puny muffin fan designed to cool a large
area...

Jim Mora

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of otmaskin5@xxxxxxx
Sent: Thursday, March 05, 2009 4:41 PM
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] Spark gaps (again)

Great explanation Deano - thanks.? 

Also thanks to everyone else for responding John, DC, Jim & Jim.

Dennis


-----Original Message-----
From: David Dean <deano@xxxxxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wed, 4 Mar 2009 11:42 pm
Subject: Re: [TCML] Spark gaps (again)



Hi

On Wednesday 04 March 2009 07:52:58 pm otmaskin5@xxxxxxx wrote:
> I've been following earlier discussions about higher losses associated
with
> multi-segmented spark gaps (i.e., Richard Quick type) compared to a single
> gap.  It's clear that the experience of this group has been power losses
> are significantly less with a single gap style with adequate airflow.  But
> I'm not sure I caught why that is.  What is the reason that a 0.27" single
> gap loses less power than an 9-gap / 10 pipe RQ gap that has total gap
size
> of 0.27"?  If total gap spacing is the same for both, why would one be
more
> lossy than the other?

I'll take a stab at this. Let us say for the sake of argument that we have
two 
gaps. Gap one is composed of two 1" copper pipes 0.27" apart. The other is 
composed of ten 1" copper pipes 0.03" apart. That is nine gaps of 0.03" for
a 
total spacing of 0.27", same as the first gap. 

Now let us assume for the moment that an air gap of 0.27" will behave
exactly 
the same way whether it is a single gap, as in the first case, or nine
shorter 
gaps added together, as in the second.

Note that the copper pipe heats up where the arc/spark touches it. Just a
little 

spot gets hot, but it heats up nevertheless. The heating of the spot is the 
same on both sides of the arc/spark. The heating of the spot, that is how
much 
energy is consumed by the heating of the spot, depends on the current
flowing 
in the arc/spark. It is a loss (I^2R) representing resistance.

In the first case with the single gap we have two spots. In the case with
the 
nine gaps we have 18 spots. So 9 times the resistance in the interface
between 
metal and spark. Nine times the energy wasted heating metal. More total 
resistance in the gap.

Of course in the real world air gap of 0.27" will NOT behave exactly the
same 
way whether it is a single gap, as in the first case, or nine shorter gaps 
added together, as in the second. The arc/spark heats the air too. It is
easier 
to blow away nine little spots of hot air than one big o
ne. 

later
deano


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