Plasma Jet Ignitition

[Robert Harris]

Why? -  All spark ignition starts with a plasma phase.  During this breakdown
phase the "blast wave" created will exceed 10 to the 4th meters velocity at
several hundred atmospheres pressure.   This injects a cloud of hyper
temperature ~60,000k free radicals into the combustible mixture.  As the
electrodes heat up and the conductance falls, the spark transitions into an
arc, where the expanding velocity drops to below local sonic and the
temperature falls to ~6000 k.   The energy transfer heat is primarily
conduction to the combustible mixture.

Increasing the size of the Plasma phase of ANY spark ignition results in
greater quantity and penetration of free radicals into the combustible
mixture.  The larger the cloud of free radicals expelled during the Plasma
breakdown, the faster and surer the ignition.  Translation - less advance
needed, faster flame front generation.  More power, more tolerance to the
cyclic F/A variations - particularly those seen by the sparking device.

There are literally hundreds of patents which I am patiently wading thru, but
there has been a lot of thought on this.

In a conventional ignition system, most of the energy is disapated in the arc
and glow stage, yet the Plasma stage determines most of the ignition
characteristics.  ANY design that pumps more energy into the plasma portion
will increase the size of the cloud and result in better performance.  And
while the lab researchers try to reach 1 joule to virtually flood the main
chamber and cause near instantaneous combustion ***** NOT DETONATION **** , I
would be quite content to pump as much as practical into the plasma stage and
suffer with only greatly extended mixture range, elimination of misfire and
near TDC timing.  

How much is helpful?  Depending on the ignition design, only up to about 2 %
of the total sparking energy is consumed in the Plasma phase.  Simply using
another CD box triggered and rigged by a diode stack to fire into the first
and modified to quickly dump its energy could potentially increase the plasma
energy 50 fold if it could dump fast enough.

>From the reading of the patents and others, simply shielding the spark in a
pre chamber reduces the energy needed to fire an order of magnitude ( why
anti-fouler improve ignition )   Combining any small pre chamber with a pumped
up plasma ignition should result in nice increase's in power and mixture
range.  Also, the patents mention controls on when to plasma pump and when not
to - just to reduce the electrical loss's to the system.  And yes, there is
also discussion of reducing the resultant emi.




1963 Ford C-600 Prison Bus Conversion "Home"
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