RE: Gap Question

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

Original poster: "Luke" <Bluu-at-cox-dot-net> 

Thanx for the input that will come in handy after I get past this
negative resistance thing which I think I am "almost" comfortable with.
Almost!

:)

Luke Galyan
Bluu-at-cox-dot-net
http://members.cox-dot-net/bluu

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, February 25, 2004 10:24 AM
To: tesla-at-pupman-dot-com
Subject: Re: Gap Question

Original poster: robert & june heidlebaugh <rheidlebaugh-at-desertgate-dot-com>


Luke: In an arc you have several conditions to consider. 1) With a low
current arc the insulation value of the gap breaks down forming a small
current path. this small current , path MAY MOVE ALONG THE CONDUCTOR BY
THERMAL AGGITATION, but remains a small current path. 2) At high current
another conditions takes place forming a plasma. A plasma forms when the
energy of the arc strips the outer shell of electrons off the atoms of
the
conducting gas. At this point the plasma becomes a conductive path of a
large area with very low resistance. A gap 2 " in distance can freely
conduct 28 volts. At normal conditions 28 volts could never be conducted
across a 2" gap. In a TC we are not using low current pulses we are
using
current pulses over 200 amps. An example of this action is an arc welder
.
The tech moves the arc rod close to the base metal to strike the arc
then
holds the arc some distance away from the base metal plate to heat a
larger
area and form a metal puddel for welding. If the tech moves the arc to
farr
a large round hole will form , not a single small point hole. This
action is
used to scrap out sheet metal in junk yards with an arc welder set on
high
currernt a 1" wide strip can be cut in old scrap for much less cost and
time
than using an expensive cutting torch. 3) The plasma action can be
proven in
several ways,  The primary proof is the sudden drop of resistance of a
gas.
this the reason flourecent lamps have a balest coil in the circuit. The
filament heats the lamp to forn a conductive vapor then the lamp
conducts
and the resistance drops. The balest then provides reactance to limit
the
current of the gas in the tube and you get light across the entire
diameter
of the tube not just one thin line of arc.  Another example is found in
inert gasses. These gasses will not form compounds and are called NOBLE
gasses. In a plasma inert gas will react with chlorine or fluorine to
make a
stable salt compounds such as zenon chloride which you can buy from a
major
chemical supply.
     Robert   H
-- 


  > From: "Tesla list" <tesla-at-pupman-dot-com>
  > Date: Wed, 25 Feb 2004 07:24:57 -0700
  > To: tesla-at-pupman-dot-com
  > Subject: RE: Gap Question
  > Resent-From: tesla-at-pupman-dot-com
  > Resent-Date: Wed, 25 Feb 2004 07:38:12 -0700
  >
  > Original poster: "Luke" <Bluu-at-cox-dot-net>
  >
  > Sorry, when I wrote gap in this post I should have said arc.
  > So when the term negative resistance is used what is meant is that
the
  > resistance value is changing in a negative direction (getting less)?
  > Is that a correct statement?
  >
  > An actual resistance value that could be measured in the negative is
the
  > picture the words negative resistance brings to my mind (sort of).
Just
  > seems like a misleading term at lest to someone new to this concept
like
  > me.
  >
  > Luke Galyan
  > Bluu-at-cox-dot-net
  > http://members.cox-dot-net/bluu
  >
  > -----Original Message-----
  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
  > Sent: Tuesday, February 24, 2004 5:19 PM
  > To: tesla-at-pupman-dot-com
  > Subject: RE: Gap Question
  >
  > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
  >
  > On 24 Feb 2004, at 13:09, Tesla list wrote:
  >
  >> Original poster: "Luke" <Bluu-at-cox-dot-net>
  >>
  >> So if the current goes up the gap widens.
  >
  > The arc channel increases in diameter.
  >
  >> If the gap widens the resistance of the gap goes down.
  >
  > If the arc channel increases in diameter, the resistance of the gap
  > goes down (assuming the arc length remains constant).
  >
  >> If the resistance went down when the current went up
  >> That is resistance not negative resistance.
  >
  > No. With a "normal" resistance, as current through the resistance
  > goes up, the voltage across it goes up and vice-versa. In the case of
  > an arc, the voltage is almost constant regardless of the current.
  > Hence, the resistance changes with current instead of the voltage.
  > Resistance in a spark gap is parametric variable.
  >
  > As Matt said, at any point plotted on a V/I curve of the gap,
  > you will find power is being dissipated. Hence at the chosen point,
  > one can derive a resistance value. The resistance value will be
  > different at different points along the curve.
  >
  > Malcolm
  >
  >>
  >> Luke Galyan
  >> Bluu-at-cox-dot-net
  >> http://members.cox-dot-net/bluu
  >>
  >> -----Original Message-----
  >> From: Tesla list [mailto:tesla-at-pupman-dot-com]
  >> Sent: Tuesday, February 24, 2004 6:52 AM
  >> To: tesla-at-pupman-dot-com
  >> Subject: RE: Gap Question
  >>
  >> Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
  >>
  >> On 23 Feb 2004, at 20:51, Tesla list wrote:
  >>
  >>> Original poster: "Luke" <Bluu-at-cox-dot-net>
  >>>
  >>> If the current goes up and the channel widens would that give the
  >>> channel less resistance because it now has a larger cross section
  >> to > travel through? > > Like a piece of 28Awg wire having a higher
  >> resistance than a piece of > 10Awg wire.  The larger cross
  > sectional
  >> area decreases its
  >> resistance.
  >>
  >> Exactly right ;)  The point is that the resistance of the gap is a
  >msnip...