[RFI] Lightning Protection
cw_de_n5op at sbcglobal.net
Mon Jul 2 06:08:39 PDT 2012
No, not effective. Again, because *everything else* is in corona (tower legs, rivets, weld sputters, bolt threads, nut shoulders, joints of all kinds) and because lightning propagation isn't driven by small variations in the local electric field, which is all these devices can accomplish. Lightning begins well aloft in the cloud, when the e-field approaches 1 M V/m and propagates at the very high e-field at the tip of the stepped leader. The downward propagating stepped leader is typically met 100-200 m above the surface by an upward-propagating streamer, which is caused by the local e-field induced by the stepped leader. All of this happens faster (think relativistic speeds) than corona currents can diffuse away from the source.
On Jul 1, 2012, at 23:21, "KD7JYK DM09" <kd7jyk at earthlink.net> wrote:
> "I asked them about these corona brushes and was told that they are
> ineffective. Once the electric field exceeds about 50-100 kV per meter,
> everything -- grass, trees, fences, antennas -- are all in corona and the
> air is about as "saturated" with corona ionization as it can get. These
> corona brushes have no effect"
> Several of htese at a site won't lower the potential in the immediate area
> preventing charges in the 50-100 kV per meter range?
> I see the diasharge brushes on remote sites, radar, repeaters, surveillance,
> even airports surrounded by towers with brush arrays a few tens of feet
> Not effective at all? What about a row of air teminals on a house?
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