"Ian White, G3SEK" wrote in message
...
Jack Painter wrote:

"Richard Clark" wrote

So much of this breathless science of rounded tips alludes to the
legitimacy of rare publications equal in scope and stature to those
that announced the proofs of cold fusion.

Did Pons and Fleishman turn their hands to designing Lightning
protection systems to redeem their credentials?

Interested in your comments *after* you have read the study.
http://lightning-protection-institut...-terminals.pdf

Yes, let's have more technical discussion and less name-calling, please.

There seem to be three observations that need to be understood.

1. The electric field gradient near a sharp point is greater than the
field gradient near a blunt point. This is basic physics and should be
completely beyond dispute. But that is the field gradient IMMEDIATELY
LOCAL to the point... and that's not what lightning protection is about.


I would think that lightning protection should begin with the safe
equalization of charges. If one could prevent localization of charge, there
wouldn't be anything to discharge. Failing that, if one could provide a
controlled discharge mechanism, that drains charge without a massive
discharge channel, that would also be good. Failing that, you fall back to a
point g defense; first dissuading the creation of a conductive channel to
the protected area, or, failing at that, providing a specific, perhaps
sacrificial path for the massive discharge.

The first methods, involving charge management, might be effected by
controlling the conductivity of the air. Chemical and mechanical methods
seem difficult to deploy and might not be able to affect sufficient volume.
I wonder if conductive air volumes, or specific channels, might be created
by RF stimulation? Might it be possible to map the atmospheric charge, and
through an array of steerable microwave exciters, create specific conductive
paths for the relatively safe dissipation of localized charge? I wonder if
the HAARP has investigated lightning control possibilities?

Ed
wb6wsn

Ed Price wrote:

I would think that lightning protection should begin with the safe
equalization of charges.

Oh, how we all wish! But think what that implies...

If one could prevent localization of charge, there wouldn't be anything
to discharge.

That would require control over the weather - and again, oh how we all
wish!

Failing that, if one could provide a controlled discharge mechanism,
that drains charge without a massive discharge channel, that would also
be good.

But again, we don't know how to do that. Starting from a weakly ionized
probe leader, lightning has a huge positive feedback mechanism. Once it
has started to go, it'll go all the way!

Failing that, you fall back to a point g defense; first dissuading
the creation of a conductive channel to the protected area,

If an ionized leader has made it all the way down from the cloud into
the region of the protected area, we don't know any way to tell it
"Wrong Way. Not In My Back Yard".

If the leader has come so close, you absolutely cannot stop what's
probably going to happen next. All you can do is do is to design the
protection system to make the best of it.

or, failing at that, providing a specific, perhaps sacrificial path for
the massive discharge.

At last, we've come down to earth. All that lightning protection can
realistically aim to do is providing a specific path. The whole aim of
lightning protection is to provide a safe discharge path *past* the
structure that's being protected, as opposed to a damaging path
*through* the structure.

A "sacrificial" path is not an option to design for. The lightning
conductor *must* hang in there for the whole duration of the stroke(s),
or else protection will be lost before it's all over.

To keep the original discussion in perspective, all this stuff about
terminals at the top end of the conductor is about trying to achieve
some kind of "come here" effect in literally the final few feet of the
entire lightning path (or tens of feet, if we're really lucky) to make
sure the leader attaches to the terminal and not somewhere else on the
structure.

The well known and most reliable way to do that is to make the terminal
higher than everything else, so it dominates the local electric field.
But that's still no guarantee that a leader won't come wandering down at
some distance off to the side, and then strike downward or even sideways
from there.


Bottom line: it's absolutely vital to be realistic about what lightning
protection can do - and also what it cannot do. A system designed out of
hopes and dreams will be the wrong system.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian White, G3SEK wrote:
The well known and most reliable way to do that is to make the terminal
higher than everything else, so it dominates the local electric field.
But that's still no guarantee that a leader won't come wandering down at
some distance off to the side, and then strike downward or even sideways
from there.

I have antennas, towers, tall trees, and power poles on my
property. Lightning chose to strike a five foot tall Live
Oak tree, killing half of it. The other half is still alive.
--
73, Cecil http://www.qsl.net/w5dxp


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

"Ian White, G3SEK" wrote in message
...
Ed Price wrote:

I would think that lightning protection should begin with the safe
equalization of charges.

Oh, how we all wish! But think what that implies...

If one could prevent localization of charge, there wouldn't be anything to
discharge.

That would require control over the weather - and again, oh how we all
wish!

I fully understand what I implied; this would be a technique well beyond our
current capabilities. OTOH, it would be a grand concept. And we wouldn't
have to "control the weather", just finesse one part of it, for a short
time, in a very local region, so it might be applicable to protecting
extremely valuable items and events, like maybe a shuttle launch or landing.


Failing that, if one could provide a controlled discharge mechanism, that
drains charge without a massive discharge channel, that would also be
good.

But again, we don't know how to do that. Starting from a weakly ionized
probe leader, lightning has a huge positive feedback mechanism. Once it
has started to go, it'll go all the way!


You don't know how and I don't know how, but that's a long way from knowing
that it's impossible. And I won't concede that there's no mechanism to
modulate a discharge.



Failing that, you fall back to a point g defense; first dissuading the
creation of a conductive channel to the protected area,

If an ionized leader has made it all the way down from the cloud into the
region of the protected area, we don't know any way to tell it "Wrong Way.
Not In My Back Yard".

If the leader has come so close, you absolutely cannot stop what's
probably going to happen next. All you can do is do is to design the
protection system to make the best of it.

or, failing at that, providing a specific, perhaps sacrificial path for
the massive discharge.

At last, we've come down to earth. All that lightning protection can
realistically aim to do is providing a specific path. The whole aim of
lightning protection is to provide a safe discharge path *past* the
structure that's being protected, as opposed to a damaging path *through*
the structure.

A "sacrificial" path is not an option to design for. The lightning
conductor *must* hang in there for the whole duration of the stroke(s), or
else protection will be lost before it's all over.


Sacrificial was a bad term; I didn't mean to imply that it wouldn't be
durable, just that it would be the path to take the hit and protect the rest
of the local area.



To keep the original discussion in perspective, all this stuff about
terminals at the top end of the conductor is about trying to achieve some
kind of "come here" effect in literally the final few feet of the entire
lightning path (or tens of feet, if we're really lucky) to make sure the
leader attaches to the terminal and not somewhere else on the structure.

The well known and most reliable way to do that is to make the terminal
higher than everything else, so it dominates the local electric field. But
that's still no guarantee that a leader won't come wandering down at some
distance off to the side, and then strike downward or even sideways from
there.


Bottom line: it's absolutely vital to be realistic about what lightning
protection can do - and also what it cannot do. A system designed out of
hopes and dreams will be the wrong system.


I HOPE I'm not there when it hits, and you're DREAMING if you think I'll
volunteer to hold the rod. That's being REALISTIC on my part. Seriously, if
all you can propose is a thick, conductive pole, then you are entering the
fight at your last line of defense. Think about the whole problem, not just
optimizing the existing solution.

And BTW, what would be so bad about having some way to create a conductive
channel from the charge to a place of YOUR choice? Even that modest goal
could vastly expand the "cone of protection" that existing masts provide.
Imagine being able to initiate safe cloud-to-cloud discharges. Imagine being
able to direct all charge for a one-mile radius to discharge (even
violently) to a designated lightning rod. One rod could protect an entire
building; several rods could protect an entire large airport. My speculation
about selection paths of ionization by RF excitation was just groping toward
one way to create those channels, and HAARP naturally came to mind.

Ed
wb6wsn

Jack Painter wrote:
"Your example of lightning was the opposite, and very rare, from the
normal occurance of lightning, which is not positively charged."

I won`t predict nor defend either polarity of charge in an overhead
cloud. In either case it will attract the opposite charge beneath.

In my example, I chose positive for the cloud because now it is popular
to characterize electrons as the mobile electrical particle. My formal
education was that regardless of what electrons do, current flows from
plus to minus. In my hypothesis, I chose to characterize what charges
were doing in the earth and other conductors. Electrons are considered
mobile due to extremely small mass, so I chose them as the moving
charge.

Effects of lightning are identical regardless of polarity or direction
of travel for practical purposes. Significant factors in lightning
protection are the maximum voltage reached across a protected device and
the current through it. We can`t do anything about the millions of volts
and the thousands of amps behind a lightning strike. We can put high
impedance between the strike and our protected people and products and
we can clamp the volts across them.

I`m sure that polarity makes no difference, one, the other, or both. For
sure you must be prepared for both because lightning is a transient. In
its start and stop, it generates powerful alternating components which
include the entire radio spectrum.

Arc gaps are effective protectors which have dependable breakdown
voltages for a given atmosphere, temperature, pressure, presence or
absence of triggering radiation, etc. Breakdown voltage is proportional
to gap width for given conditions. Electrode shape is significant in the
striking (breakdown) voltage. Blunt electrodes require significantly
more volts to arc across than do needle points. Anyone in the TV
business knows that corona discharge from the high-voltage circuit
occurs from a sharp point. Once a corona is producced from a point,
conductance extends as far as the corona reaches.

I agree that charged air arrives in advance of a thunderstorm, whatever
the polarity of charges may be. I`ve spent many years in broadcast
stations and observed the storms. Before the storm arrives, tower guy
insulators flash across from charges picked up by the guywire segments
out of thin air.

On arrival, a bolt from the sky hits a tower or towers. Maybe it`s the
reverse that occurs. It makes no difference. The station and its
equipment are protected by the tall towers. In lightning rods, more is
better. All the stations in my experience used multitower arrays. None
ever had significant lightning damage. Much of the time they were
operating 24-7 and they might be dropped from the air for an instant due
to a temporary overload caused by the lightning strike.

The medium wave stations I worked in had blunt lightning discharge
electrodes. Lowest breakdown voltage wasn`t a requirement. The final
amplifiers used vacuum tubes and were sturdy. The tower base insulators
all had ball gaps side by side across them. Precipitation fell right
through to have little effect on their striking voltage. Tower balls
never fire anyway. It`s always the Faraday screen between the primary
and secondary of the tower coupling transformer thet takes the lightning
hit. The impedance and striking voltage are higher at that circuit
point. The screen is heavy and easily withstands lightning strikes.

The shortwave stations I`ve worked in, all had arc gaps at the feedpoint
of their parallel 600-ohm transmission lines. These were adjusted so
that they just had 10 thousandths of an inch more than the minimum
spacing required to prevent breakdown on full 100 KW carrier output with
100% modulation. These gap electrodes were consstructed like the letter
V turned so one side was horizontal and the pointed ends of the V`s
pointed to each other. The upward slope of the arc gap meant that heated
air in the gap would rise increasing the arc distance so it might
self-extinguish. We never had any lightning damage in the short wave
plant with its dozens of antennas, lines and transmitters.

Sharp points lower breakdown voltage. In a situation where charge across
a capacitance, auch as between a cloud and the earth, has increased to
the breakdown value, it happens where there there is a sharp point in
the neighborhood of the charge concentration.

Blunt electrodes require higher potential to flash over than sharp
electrodes. For given electrodes in a controlled environment, the
distance between electrodes can be calibrated in volts required to jump
the gap.

Arc gaps are spaced to clamp the maximum voltage across them to a safe
value. CRC`s "Handbook of Chemistry and Physics has a table of the
voltages for blunt and sharp electrodes.

Best regards, Richard Harrison, KB5WZI

"Ed Price" writes:

...
And BTW, what would be so bad about having some way to create a
conductive channel from the charge to a place of YOUR choice? Even
that modest goal could vastly expand the "cone of protection" that
existing masts provide. Imagine being able to initiate safe
cloud-to-cloud discharges. Imagine being able to direct all charge for
a one-mile radius to discharge (even violently) to a designated
lightning rod. One rod could protect an entire building; several rods
could protect an entire large airport. My speculation about selection
paths of ionization by RF excitation was just groping toward one way
to create those channels, and HAARP naturally came to mind.

A long time ago, there was some (theoretical at least) effort to see
whether UV lasers could be used to create an ionized channel over a
long distance. Something like that might do the job. OTOH a
rainstorm is generally pretty opaque to UV.

Teh RF excitation has already been tried -- I think someone has a
patent on it. One problem with it is that where there is lightning
there tends to be wind, so that the ionized air is blown away faster
than it can be generated.

Regards,
Allen WA0OHE

On 07 Jan 2005 16:46:54 -0600, Allen Windhorn
wrote:
My speculation about selection
paths of ionization by RF excitation was just groping toward one way
to create those channels, and HAARP naturally came to mind.
A long time ago, there was some (theoretical at least) effort to see
whether UV lasers could be used to create an ionized channel over a
long distance.

Hi Guys,

One has to wonder about the consequence of double jeopardy standing
beneath that antenna (HAARP experiment) or holding the laser.

Think insurance covers this?

Supply shop foreman (perplexed):
"Another laser? What happened to the last one?"

Tech (smoke curling up from clothes):
"ummmm, burned out real quick-like. Could you hurry? They say
more rain is on the way!"

73's
Richard Clark, KB7QHC

"Richard Clark" wrote

On Fri, 7 Jan 2005 01:53:00 -0500, "Jack Painter"
wrote:
Interested in your comments *after* you have read the study.
http://lightning-protection-institut...-terminals.pdf

Hi Jack,

"It is quite obvious from these plots
that the experimentally determined electric field
strength is less than the "simple-minded" V/d value."

Interesting brush-off so early in the paper begs for real editorial
control. As very few would experience lighting sourced from a grid of
wire 5M overhead this paper seems an example of the "laboratory
factor" it set out to examine and yields a paper confined to
laboratory arcana. All fine and well, but what is the point?

"There is an urgent need for detailed theoretical
modelling which can quantify the space charge
effects around air terminals, particularly in
relation to upleader development."

Which seems at odds with your statement:
On Fri, 7 Jan 2005 01:17:07 -0500, "Jack Painter"
wrote:
The junk-science of early-streamer-emission
but I'm not terribly interested. I wasn't particularly intrigued by
Pons and Fleishman either, beyond the hubris of their closet drama.

It would seem some have a desperate need to topple Franklin from a
pedestal of their own building. (Theirs is called the fallacy of
"present mindedness.") I'm satisfied that contemporary Europeans held
him in high esteem for many noble achievements. Reductionists are
measured against their own few of baser metal.

Hope you found that interesting, but I doubt it - rather banal stuff.

73's
Richard Clark, KB7QHC

Richard,
Thanks. I always find your comments about scientific material interesting.
There is some monumental evidence accumulating to contest ESE/CTS, and this
begs the question that if there is such a political fight over preventing
its presentation to the whole IEEE body for a vote, what are they so afraid
of? Russian scientists have now been commissioned to find (contrary to all
other studies) that the principle works. Avoiding the comments about
streamers in the referenced paper though, my point really was that they
arrived at a statistical average they may have been looking for, but
attempts to remove the laboratory principle appeared honest to me (and to
others). Your opinion there is important, at least to me.

73,
Jack Painter
Virginia Beach, VA

On Fri, 7 Jan 2005 20:23:28 -0500, "Jack Painter"
wrote:

Thanks. I always find your comments about scientific material interesting.

Hi Jack,

Well, when I look at these tempests in a teapot, I reduce things
myself.

For instance, this distinction between a sharp point on a rod and a
blunt point on a rod. Nature hardly takes the time in a lightning
strike to be so particular. This is so multivariate a problem that no
single variable is going to be a determiner at this rather fussy level
of detail.

The reduction consists of the logic in the extreme. We have a blunt
rod, we have a sharp rod. It is purported (or I have read the
controversy completely wrong) that this makes a difference, somehow.
We put those on a yet blunter rod (a tower); or with a yet blunter rod
(another tower) nearby (in the scale of miles transit, nearby by
hundreds of yards/meters/feet/inches/cm is very proximal) and yet such
neighbors are not the choice of the stroke (or they are and this
upsets the catalogue of evidence).

Hence the reductio ad absurdum is that blunt points are significant,
but not too significant.

All that aside - I do not dismiss the topic entirely. It offers
something I have found in my own work. The near field area to a
monopole:
http://home.comcast.net/~kb7qhc/ante...ical/index.htm
displays a very marked disturbance above it. The introduction of a
metal pole into space distorts it far beyond the borders of the
graphic pointed to. In a sense, it acts like (in my imagination) the
vertex of a energy well; or at greater scales, a dimple in the fabric
of the æther. Such analogies and illustrations are intriguing, but
not conclusive of anything but how to intellectually amuse while
monkeying with numbers.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On 07 Jan 2005 16:46:54 -0600, Allen Windhorn
wrote:
My speculation about selection
paths of ionization by RF excitation was just groping toward one way
to create those channels, and HAARP naturally came to mind.
A long time ago, there was some (theoretical at least) effort to see
whether UV lasers could be used to create an ionized channel over a
long distance.

Hi Guys,

One has to wonder about the consequence of double jeopardy standing
beneath that antenna (HAARP experiment) or holding the laser.

Think insurance covers this?

Supply shop foreman (perplexed):
"Another laser? What happened to the last one?"

Tech (smoke curling up from clothes):
"ummmm, burned out real quick-like. Could you hurry? They say
more rain is on the way!"

73's
Richard Clark, KB7QHC


Well, I could easily imagine a laser protected within a large conductive
lightning rod. All you need is a 1/" hole in an otherwise well-shielded
structure. Maybe a bit larger to allow for pointing, or you could put some
optics safely outside the rod.

Regarding the RF excitation, I assumed that a single-point source would be
dumb, because the best ionization path would be right back to YOU. But an
array of exciters, electronically steered to create a sufficient power
density at a focal point, is a lot smarter.

Again, I don't know if the technique would work, but an electronically
steered (more like focusing) array would be one way to do it.

One poster said that the ionized channel might blow away in the wind. Maybe
a quick system could "paint" an ionization channel fast enough. Maybe a
system could detect and take advantage of leaders, to create a shorter path.

Ed
wb6wsn