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critical damping of spark discharge
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From: Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
Sent: Saturday, June 06, 1998 7:43 AM
To: Tesla List
Subject: Re: critical damping of spark discharge
Tesla List wrote:
>
> ----------
> From: Jim Lux [SMTP:jimlux-at-earthlink-dot-net]
> Sent: Friday, June 05, 1998 7:05 PM
> To: tesla-at-pupman-dot-com
> Subject: critical damping of spark discharge
>
> I have discovered that the EG&G application note talking about
> critically damped RLC circuits with a spark gap is now available on the
> web:
>
> http://www.egginc-dot-com/bin/webmate/Opto|111/page/egg/1300tb1
>
> Now, this talks about the stuff for flash tubes, however, by suitable
> (?!) adjustment of the Ko parameter in the Goncz equation, it should
> work for an air spark gap.
Jim and all,
The difference between the flashtube and a free-air arc is that the cool
sidewalls of the flashtube actively cool the arc plasma. This additional
boundary condition results in a positive ("resistive") VI curve once the
arc current exceeds a critical level.
An arc in free air can expand with increasing current density, resulting
in a negative VI characteristic for lower arc currents (10's of amps),
and a virtually flat, zener-like clamped voltage VI characteristic for
higher currents. At very high currents there's a very weakly positive VI
characteristic primarily due to electrode resistance effects.
The flashtube and free-air cases are unfortunately not comparable...
-- Bert --