Power VS Arc length

[Factor5]

Currently i am attempting a project which involves making an arc go across two nodes. they will be approx. 8 inches apart. What i really need to know is how much power i'll need, or a formula to calculate the relationship between Power and arc length... I'm no physics major, so take it a little easy on your brainiac stuff i also would appreciate help on building a device like this, depending on if i need to use a capacitor or tesla coil or something.... any help or input would really be appreciated... thanks all

 

[DnetMHZ]

check out this paper on Paschen's Law




<< In 1889, F. Pashchen published a paper ( Wied. Ann., 37, 69) which set out what has become known as Paschen's Law. The law essentially states that the breakdown characteristics of a gap are a function (generally not linear) of the product of the gas pressure and the gap length, usually written as V= f( pd ), where p is the pressure and d is the gap distance. In actuality, the pressure should be replaced by the gas density.

>>



Hope that helps
DnetMHZ

 

[RossGr]

I do not think power is the key factor here, you will need a pretty high voltage to jump that gap. It can be and should be low power. Consider a static spark, I have seen static jump 4" -6" this was ~40KV. My understanding is that it takes about 10Kv per inch of spark, this is rule of thumb and as the above poster pointed out will vary with the air (or what ever gas) pressure.

As long as you can be sure that you have a low current the power will be low. That way mistakes on your part will be painful but non fatal!

 

[Factor5]

Thanks guys... i searched for this for a few days, and was stumped... but i think i got it figgered.... i'll try to keep the amperage low as to not melt stuff, and/or elecricute myself.... the help was greatly apprecaited...

 

[Superdoopercooper]

Yeh... its all about VOLTAGE. Air has a breakdown voltage of 30,000 volts per meter or something like that... so if you want to go 8 inches... you need about 8/40 (approx 40 inches in a meter)... which equals 1/5 * 30,000 = 6000Volts.

The 30kV/meter may not be right... but that is really the only equation I think you need.... V(needed) = distance * breakdown voltage of the medium.

 

[kylef]

Also, keep in mind that environmental factors such as humidity (and therefore temperature) play a significant role in determining the dielectric breakdown potential of air. Attempting to calculate the precise amount of potential to arc is extremely difficult due to the nonlinear nature of the dielectric. However, you can obtain a ballpark estimate by assuming a vacuum.