Spark Gap Sustaining Current (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 27 Sep 2007 12:55:46 -0500
From: Crispy <crispy@xxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Spark Gap Sustaining Current

Hello,

I have a quick question about spark gaps.  How much current is required
to sustain an established arc in a spark gap in "dead air"?  Let's say
that there are two tungsten contacts about an inch apart, and an arc is
ignited by a voltage of a little over 20kV.  Say that the ambient
temperature is room temperature and that there is not significant
airflow through the gap other than that which is generate by the gap's
heat itself.  Is the sustainability of the arc purely a function of
current through it?  If so, in such a theoretical gap, how much
sustaining current would normally be required?

Thanks,
Chris