Re: spark gap ATTN: Bart

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Tim,

I envy you!

The 1/2" copper I've never worked with. It will be interesting as 
I've heard about problems machining copper for years on the TCML. I 
used brass myself as it was relatively inexpensive through 
McMaster-Carr. With a 6 foot piece, you could certainly make a high 
number of electrodes which may be very beneficial using the largest 
number of electrodes possible with the airflow design you have in 
mind and minimal spacing between electrodes. Cooling is important in 
any gap, so first determine how you will direct air flow and the area 
you have available for electrodes. Vacuum or blowing both work if 
done right. The TCBOR/RQGAP is very helpful for either situation. I 
went with the vacuum myself in this design because all the air flow 
can be directed to the electrodes, where in a static gap say on a 
flat slab with only a fan over them waste available air and thus cooling.

The radius of curvature and total gap spacing are both considerations 
for arcing at the expected voltage (hmm, what do coilers assume that 
is? NST output voltage? no way!). For 1/2" electrodes, ideally, I 
would set the total gap spacing at 600 mils for 15kV transformer. I 
would also argue for 11 electrodes which permits 10 individual gap 
spacings at 60 mils between electrodes, which also ensures a good 
deal of mass). This may seem excessive (it's not to me). The cap will 
see about 24kV with a 15kV NST. Also, if the coil is running a 
0.025uF cap size, 860 Amps primary current is the bang! This is 
massive current and is felt in the form of heat at the gap 
electrodes. My reason for mass may see some acceptability when this 
is considered (which it probably hasn't in these discussion).

Anyway, yes, keep us informed. Sounds like a very cool gap to build! 
I'm throwing 20% of every pay check towards retirement and have about 
30 years of work time to go. So, little is left for machine tools. 
Should I ever win the lottery, stand back!

Take care,
Bart

Tesla list wrote:

> Original poster: Timjroche@xxxxxxx
> Bart,
>  Fortunately I have a CNC mill and lathe....been a machinist for 
> quite a while now....long before my TC work, at least... 1/21/06 
> 11:00am...I got a 6' piece of .5" copper round stock, headed into 
> the shop...I'll let you know how it goes..
>
> Tim