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Re: Spark Gap Gasses Experiment



To all spark gappers,

<snip>
> > >    At work we have a hydrogen spark gap with operates at up to
> > >30atm pressure, it is not used with tesla coils, but it is in a
> > >capacitor discharge circuit, and the quenching is INCREDABLE, we can
> > >operate it with primary energies of 10's of joules per discharge with
> > >rep rates over 5KHz, and even then it is not the gap which is the
> > >limiting factor, but the system it is driving.
<snip some more> 


The above is not a new idea.  In the early 1900s, experimenters learned
that they could create RF in the 20-100 KHz range using a carbon arc
driving a resonant circuit.  The carbon arc exhibited negative resistance
effects and so could function as an oscillator.  Getting the arc to quench
at radio frequencies was done by running it in a hydrogen atmosphere and by
using very strong electromagnets.  The arc voltage was around 500 volts DC
at many amps.  The largest arc transmitters were in the million watt range,
using many-ton magnets, water cooled arc chambers, etc.  There is some
fascinating reading about these devices on the web.  I will list a few of
the sites to whet your appetites:

http://home.luna.nl/~arjan-muil/radio/poulsen.html
http://metronet-dot-com/~nmcewen/Federal_Telegraph_Relay.html
http://www.asb-dot-com/usr/w2g3zfj/about.htm   

So, what does this have to do with TCs?  Two thoughts:

For one thing, we can certainly benefit from these spark gap pioneers to
improve spark gap quench.  Apparently, if one is careful, one can use
alcohol dripping on the hot spark gap electrode to generate a hydrogen
atmosphere.  The heat decomposes the alcohol (or kerosene) into hydrogen. 
Of course, the spark chamber must be free of oxygen to avoid an explosion. 
The old timers also used "illuminating gas" which would also break down
into hydrogen.  Would natural gas do the same thing?  Running natural gas
in a spark chamber for a minute or so would drive out the air and should
then be safe to turn on the juice.  See the above web sites for interesting
details of these arc systems.  

And what about winding a few turns of conductor going to and from the spark
gap to generate strong magnetic fields to help "blow out" the spark?  The
hundreds to thousands of peak amps through a few turns of copper tubing on
either side of a spark gap should generate a very strong magnetic field.

Secondly, these arc transmitter ideas obviously can be applied to driving a
tesla coil without the need for high voltages.  I suppose this has actually
been done, but I am not aware of any references describing an actual setup
and results.  I would be interested in what the DC input power to RF power
conversion efficiency would be for   a 500 volt 20 amp (10 KW) Poulsen
oscillator/tesla coil, for example.  I am guessing efficiency would be
lousy, much worse than a more traditional high voltage powered TC.

I would enjoy your comments and further ideas on this subject.

--Steve Young