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Magnetic Quenching of Spark Gaps
From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: Monday, September 22, 1997 5:49 AM
To: Tesla List
Subject: Re: Magnetic Quenching of Spark Gaps
Tim Raney wrote:
> I probably missed the earliest posts on magnetic quenching. I am not aware
> of attempts to use magnetic quenching for rotory spark gaps. I would think
> the aerodynamic properties (laminar flow) of the rotor would clear the ions
> and assist in quenching. My summary only addressed static gaps.
> Additionally, the magnetic field does not have to be "moving" per se or even
> pulsed to influence charged particles, i.e.; electrons, ions, etc. A
> magnetic field influences charged particles regardless of the relative
> motions of the two. Even if the magnetic field and the electrons or ions are
> parallel, they will spiral along the field lines.
It is true that they will spiral, provided that they have even
a little movement to start them going. From a perfect standstill,
however, there could be no acceleration force due to F = qvB,
where v is the charged particle's velocity relative to the field.
In most practical cases though, a perfect standstill is almost
impossible to obtain.
In any case, a spiral trajectory is probably not the quickest way
out of the gap, if at all. An intense, rapidly moving field seems
like the most effective way to employ magnetic quenching, if it is
feasible at all for higher power levels.
> As for "lingering" electrons or ions existing after the gap fires, you have
> to consider atomic recombination. This phenomena exists regardless of what
> gap you are using. In recombination, the electrons attach themselves to
> positively charged ions almost immediately (recombination rates vary from
> microseconds to a couple of milliseconds). The resulting atoms are then
> neutral again (though ionized atoms are always around...a product of
> terrestrial background radiation and cosmic rays. Additionally, electron and
> ion velocities (accelerated by the gaps' potential) can scatter and move away
> from the gap. You would have to design an experiment to show "a relatively
> stationary ion cloud" exists around the stator and rotor electrodes of the
> rotary gap. I think the factors discussed above make this condition almost
> non-existant. Hope this helps!
Rotary gaps do have problems with quenching, even with recombination,
diffusion, and air movement working in our favor. It's just that the
beat envelopes are usually much quicker than these restoring effects.
If we could just get rid of the moving parts and those pesky, high
temperature ballistic electrons and ions, then the rotary gap would be
a far more reliable device.
-GL