Re: Air blast SG question

[Pyrotrons-at-xxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

<< Hi all,
 
I like to know if some of you make test on air blast SG. I want to know
if you had compare wide gap with small air flow vs narrow gap with high air 
flow. What is your conclusions ? about quenching, general performance, etc.
 
Luc Benard >>

Hi Luc and all...

With a given gap spacing, increasing the velocity of the airflow will cause 
the gap to break down at a higher voltage (as if widening the gap). The 
faster-moving air "blows away" the ions before they can create a path for the 
discharge.

I have stopped a 15kVRMS (20kV peak or so) transformer from arcing across a 
1/4" gap before. 
 
I've found that quenching is great with a single static airblast gap, IF and 
ONLY IF you have enough airflow. Aron and I built and experimented with one 
once, and found the results to be similar to a RQ style multiple static gap. 
However, I will say that it is difficult to compare an airblast gap to other 
gaps, because the airflow significantly affects the breakdown voltage. 

IMHO, I like airblast gaps. They're reliable, can handle lots of power, and 
are easily constructed. Downsides are that they're a bit hard to adjust 
(sensitive to spacing), require a source of high pressure air, and they're 
LOUD!! 

As far as setting the gap spacing: I suggest turning the air on, and placing 
your transformer (that you'll be using on your coil) across the gap. Just the 
transformer itself, completely out of the coil tank circuit. Anyhow, turn on 
the airflow and the transformer. If the gap doesn't break down, start 
decreasing the space between the electrodes until it does. You will be 
surprised how close the electrodes will be when it finally arcs over!!

If you use it on your coil and the gap doesn't quench (big "flame" look to 
the gap, sputtery sound, poor coil performance, etc.), then you probably need 
more airflow. The more power you run, the more airflow you need. Just 
remember that, increasing the air velocity will increase the breakdown 
voltage. Coil components could be overstressed if you don't watch it ; ) 

Hope this helps! Take care,

Justin Hays
KC5PNP
Email: pyrotrons-at-aol-dot-com
Webpage: www.hvguy-dot-com