Fw: [TowerTalk] snow static, Quad v. Yagi

[Jim Lux]

----- Original Message -----
From: "Jim Lux" <jimlux at earthlink.net>
To: "Tom Rauch" <w8ji at contesting.com>
Sent: Wednesday, September 01, 2004 7:40 AM
Subject: Re: [TowerTalk] snow static, Quad v. Yagi


> No.. sparks to the air. Tesla Coils, St. Elmo's Fire, Airplane p-static,
the
> crackle of a charged Van deGraaff generator, and corona discharge, are all
> examples of what we're talking about here.
>
> When the charge on a conductor gets to where the E-field at the surface
> exceeds the breakdown voltage of the air, it will breakdown and start a
> leader (which typically dies out real fast, unless the object is large, or
> there's a continuing charge source). The production of that leader heats
> up/ionizes the air, the energy for which comes from the charge on the
object
> flowing into the leader.
>
> The potential of a charged dust particle, in isolation, is hard to define,
> as is a conductor in free space, but usually, one can take it as being the
> same as the potential relative to "ground" (which I realize is hardly
> isopotential in the context of thunderstorms, etc., but still has some
> meaning).
>
> In any case, if I shoot charged particles at a conducting object, and they
> touch, the charge may transfer (there will be an electrostatic force
tending
> to repel the particle, so some of the kinetic energy of the particle is
used
> up in doing work against that electrical field, which is how the "energy"
> accumulates in the conductor).  As charge accumulates on a conductor, the
> voltage (measured relative to some far away reference point) increases.
> Likewise, the field increases, since it's proportional to the voltage.
>
>
>
> ----- Original Message -----
> From: "Tom Rauch" <w8ji at contesting.com>
> To: "Jim Lux" <jimlux at earthlink.net>; <jimjarvis at comcast.net>;
> <towertalk at contesting.com>
> Sent: Tuesday, August 31, 2004 6:31 PM
> Subject: Re: [TowerTalk] snow static, Quad v. Yagi
>
>
> > > The charging current should be quite low, since the
> > antenna is physically
> > > fairly small.  The cases reported in the literature of
> > continuous sparks are
> > > from things like miles of telegraph wires strung across
> > the prarie.
> > > On an antenna with no DC path to ground (say there's a
> > transformer balun)
> > > then there's no path for the charge to ground, so it will
> > just build up
> > > until it sparks into air.
> >
> > I think you mean until it sparks to ground Jim! The charge
> > is the same potential as the air at the antenna height.
> >
> > 73 Tom
> >
> >
>