RE: PSPICE model for Static Spark Gap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

I made a first order model of a static gap with Pspice.  This model has 
fixed (but adjustable) static breakdown voltage, ON resistance, and quench 
time.  See http://www.laushaus-dot-com/tesla/gapsim.htm.  Now if you really 
want to get into it, the on-resistance of a gap is dynamic, varying with 
current.  Marco Denicolai made a Pspice model that accurately shows the 
linear decrement, but the functions he used are not included with the demo 
version of Pspice.  The URL that I have for his web site doesn't seem to be 
working, but his simulation page was at 
http://www.saunalahti.fi/dncmrc/th_sim.htm.

Simulating the quench time will certainly be challenging!  I'm not sure the 
fundamentals are presently understood well enough to predict exactly when a 
gap will quench.  I think for now, we'll just have to make assumptions 
about first, second or third notch quenching and set the gap conduction 
time to these time intervals.

You may also wish to look at 
http://www.spectrum-soft-dot-com/down/winter99.pdf, which shows how to model a 
spark gap (but not with Pspice).

Lastly, if you're serious about generating a very accurate model, I think 
the present models we have for NST's are deficient in accounting for 
non-linearities in the current limiting shunts.  I think this has a larger 
impact on the final outcome than the error introduced by gap non-linearities.

Regards, Gary


  -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com]
Sent:	Tuesday, December 10, 2002 10:29 AM
To:	tesla-at-pupman-dot-com
Subject:	PSPICE model for Static Spark Gap

Original poster: "Mccauley, Daniel H by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>



I'm interested creating a simple static spark gap using PSPICE.  Anyone have
a model they are already
using.  Right now I'm thinking its just going to be a voltage-controlled
switch.  Basically, when the
voltage exceeds some voltage X, it will close the switch.

However, the tough part of the model would be the following:

A.  Impedance of the arc
B.  Quenching of the arc
C.  The duration of the arc (at which voltage / current limit) will it
extinguish (B. probably also part of this)


Any help appreciated.  I'm planning on creating a simulation for my minicoil
running on a 4kV, 20mA NST and want an
accurate enough model so I can explore the use of PSPICE design to create a
tesla coil with longer streamers etc...


Dan