Re: Streamer models used with Terry's new program

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Original poster: Steve Conner <steve@xxxxxxxxxxxx>

Hi Gerry, comments in the text

> The start point would be zero voltage on the topload and a bang is 
> starting to ring up. One would integrate the RF current flowing into the 
> topload and compute the accumulated charge and voltage on the topload 
> using its capacitance (with no streamer loading present) and the time step 
> used in the program.  The voltage would increase (in a sinusoidal way) 
> until the breakout voltage was reached.  Any current flowing into the 
> topload after breakout occurs would result in excess charge going into the 
> streamer channel.

All sounds fine so far ;) Antonio's simulation code could easily do that.

>   If one could estimate the channel size needed to absorb the excess 
> charge perhaps using ambient temp and pressure, one could estimate the 
> added capacitance this presented to the topload.

Here's where it starts to get tricky. I thought of one possible simple way 
to do it. In chemistry handbooks you can find ionization energies for 
nitrogen and oxygen, ie so many kJ to ionise one mole of the stuff. Or 
maybe (since you're dealing in charge) you could use the Faraday constant, 
that says it takes 96500 (iirc) coulombs to singly ionise one mole of 
anything. Also you know one mole of any gas is about 22 litres at STP or 
whatever. So you could estimate what volume of gas gets ionized by a given 
amount of charge, and make some assumptions about how it's distributed 
(sphere, cone, fractal, whatever) to get a surface area and hence a 
capacitance.

Possible problems with the Faraday constant approach- It doesn't take 
impact ionisation into account (one loose electron- so one quantum of 
charge- can ionize several atoms) nor account for the fact that current 
might flow through previously ionized gas rather than creating fresh ions. 
I don't know enough about the physics of atmospheric pressure discharges to 
visualise how that would affect the result.


> Dont know if this is a correct way of thinking of streamers (either partly 
> or completely)

Neither do I :P I'm wondering if there is a way to digitize two waveforms 
from a coil (secondary base current and primary current?) and process them 
to graph streamer load impedance in real time as a bang progresses. I don't 
know if that is theoretically possible, maybe you need four waveforms since 
a dual resonant system has four state variables.

Steve Conner