Re:Humid atmosphere

>>From paulmil-at-ibm-dot-netSat May 18 08:10:13 1996
>Date: Sat, 18 May 1996 04:06:21 GMT
>From: paulmil-at-ibm-dot-net
>To: tesla-at-pupman-dot-com
>Subject: Re:Humid atmosphere

>Question was:-

>>like to pose another question. How much effect does atmospheric conditions
>>play on arc length? I'm looking for generalizations as to humidity, air
>>pressure. altitude won't I get a long streamer? Some of you guys must have
>>experience operating coils in different locations.
>>I hope I never stop learning.


>I am in Kuala Lumpur with a big six foot coil trying to demonstrate it to
>the locals. Inside an air conditioned building I only got 2ft sparks and
>attributed this to the high humidity. The air con greatly reduces the
>humidity but it is still very high.

>The next demonstration was outdoors in the tropical jungle in a temperature
>of 34 deg C and humidity over 60%. I got only 4inch sparks in this humidity.
>I think the answer to your question is that the humidity kills the sparks.

>I was hoping someone might be able to tell me how to make the arc travel
>through the humid atmosphere as a six ft coil with 4inch sparks is very
>embarrasing. I also have a 14" desk top coil which also makes 4 inch sparks.
>I noticed the same thing with the Van-Der-Graaf generator. In the jungle
>atmosphere my 30 inch dome machine could not manage more than 1/4 inch
>spark.Is there any way round this problem or am I going to appear as the
>foreign failure to Kuala Lumpur.

>It appears that the amount of power you put into any arc is irrelevant in
>high humidity, you only get small arcs. Is there any theory on this
>anywhere. There is also no corona.

>Paul Millott.

Paul and The Group,

My experience is that dry air like the kind you get in your house in 
a typical Canadian winter is almost the hardest to make a long 
streamer in.  Go outside where its just as dry but minus 20 degrees 
and the air becomes more dense making it even harder to ionize.
Look at those partially evacuated plasma globes that Radio Shaft and 
other stores sell, they make terrific streamers with just a dinky 
15 KV high frequency supply because of the reduced atmospheric 
pressure.  I'd love to be a coiler in Denver, Colorado on a humid 
summer nite (does it get humid in Denver?).  I think the display 
would be great.  However I would not want to be a Denver coiler , 
happy with his coil performance and travel to a coil competition 
somewhere near sea level in Canada in the winter ( like my location 
in Ontario).  Hey, is this thing plugged in?

On my small 15KV -at- 60 MA neon powered coil, inside the dry house in 
winter the streamers are only about 3 feet long.  Indoors or out on a 
same temperature very humid summer evening the streamers are about 4 
feet long.  That's a full 25% improvement!  I've seen this coil behave this way
over and over again. I'm certainly convincved!

As long as the moisture in the air IS NOT CONDENSING, i.e. that you 
are operating above the dew point, I think you shud be fine.  If 
there is actual  water condensate coating your coil and it is a high power 
machine you are probably tempting disaster from carbon based 
flashover damage.

Van de Graaff's on the other hand are affected enormously by trace 
amounts of humidity, condensing or not.  Ol' R.J. Van de Graaff 
himself reported that by completely sealing up their giant Round Hill 
electrostatic generator so that it was 100% air tight, coating the 
outside of the textolite column with ceresin wax to seal it against 
hygroscopic absorbtion, and by operating an electric heater inside 
the base, column and top terminal assembly (all one common volume), 
and by also operating a heated silica gel based dehydrator unit 
inside, that they could achieve full machine output voltage 
consistently in 100% ambient humidity!

Perhaps a home made VDG could be sealed up and a domestic freon 
refrigerator based de-humidifier unit could be 'plumbed' into the 
system with flexible plastic air duct like that used to vent a 
clothes dryer outside?

I would be interested in hearing feedback from others who have 
observed humidity based effects on their Tesla coils.

Happy coiling!, rwstephens