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Re: Streamer modeling

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Antonio,

At 08:14 PM 6/30/2005, you wrote:
....

It's simple to change the code to allow time-varying elements.

I just "tore the guts" out of scan Tesla to do it ;-)) But the resulting code is much cleaner now ;-))

http://drsstc.com/~terrell/modeling/ScanTesla740.ZIP

NOT a well tested version!!!

If one enters a positive value for Cload increment (C3_inc) it works normally. But if the value is negative, it simulates a streamer dynamic load with C3_start as a "seed" value. The code will skip the time wasting stuff when it can... It just skips redoing the A matrix stuff if the C3 variable is not changing all the time. So the program works just like before if C3 is not dynamic with the same fast speed...

I found that it is hard to get the streamer load "started"!!!! If C3 starts out as zero, the load power is zero and it never starts.... I fiddled with it and this is the best I could come up with at 12:30 am tonight ;-))

// Dynamic streamer model****************
LeaderLength = 2.4*sqrt(Eload*BPS);
if (C3_inc < 0)
{
if (LeaderLength <= 30.0) {C3 = 0.06666666667*LeaderLength*1e-12;} else {C3 = (0.15*LeaderLength-0.25)*1e-12;}
if (C3 < C3_start) C3 = C3_start;
}
// Dynamic streamer model****************

I am testing
now a version of the calculation engine where the capacitances and resistances
can change. The present model for the streamer load, C2 (part), R3, and C3,
can then be made to change to simulate breakout and streamer growth.
The problem is how they change. In a first approximation I am trying to
leave R3 constant and increasing C2 and C3 when the terminal voltage
exceeds a certain breakout voltage, by equal amounts that return the terminal
voltage to about the breakout voltage.

C2 should "really" never change... I try to mess only with C3... Maybe make an arm waving "corona capacitance" and stuff ;-))

The result is that the load capacitance
increases at the voltage peaks, and more power is dissipated in the fixed
streamer resistance R3. Detuning limits the increase at some point.
If this makes sense, streamer length can be estimated by the increase in
the streamer capacitance.


Ok :-))  I don't know at this point ;-))

Cheers,

        Terry


Antonio Carlos M. de Queiroz