Jim Kelley wrote:
chuck wrote:

Cecil Moore wrote:

chuck wrote:

Based on that, it would seem the fairweather field can support
corona formation by itself.


Even though the fairweather current is 13 magnitudes below
the corona current?


My understanding is that a strong electric field ionizes the air and
leads to formation of a corona. I imagine with a sufficiently strong
field, the corona current could be in the pA range. At least I can't
imagine why not.

Here's an exercise that might add some realism. Calculate the amount of
charge a 14 awg 40 meter dipole antenna at 35 feet would have to
accumulate in order to generate a strong enough field to cause a corona
discharge. (Arcing at the feedpoint doesn't count.)

73, ac6xg


OK. So you understand that it is not
necessary that a conductor be charged in
order for a corona to be formed. It
needs only to be placed in a
sufficiently strong electric field.

But if there is no external field
assumed, then the required charge on the
wire would be that which will produce
the requisite field intensity at some
chosen place on the wire.

The "pointier" the place you choose, the
smaller the necessary net charge. Any
charge on the wire will be distributed
over a real wire but concentrated where
there are sharp points.

As the radius of curvature of a "point"
on the wire, such as a dust particle
stuck to it, approaches zero, the
quantity of charge necessary to cause a
corona becomes quite small. That's about
as close as I can come to realism, Jim. ;-)

73,
Chuck