EMP effects on ammo
ra...@ihlpm.att.com
since the shell of the smallarm round is itself a Faraday cage, and since
the shell itself would reradiate EM radiation, one presumes like metal
chaff used against radar, can there be much radiation that would be
ansorbed and somehow converted to heat? A brass shell I'm sure has very
low electrical resistance, so I can't imagine much energy being absorbed.
Mark Smith
#I guess I'm a bit confused by the possible effects of EMP on ammunition;
#since the shell of the smallarm round is itself a Faraday cage, and since
#the shell itself would reradiate EM radiation, one presumes like metal
#chaff used against radar, can there be much radiation that would be
#ansorbed and somehow converted to heat? A brass shell I'm sure has very
#low electrical resistance, so I can't imagine much energy being absorbed.
How about a net effect of ZERO! The military did all sorts of
experiments on people and equipment back in the 40's and 50's by going
out in the desert and detonating nuclear devices with troops out there
too.
You also have a misconception about chaff and radar. Chaff does NOT
reradiate any energy detectable by radar sets. It is a REFLECTOR. It
would be the same as dropping highly polished tin foil (chaff) into the
beam of a spot light. You'd see all sorts of bright flashes out in the
night.
Mark
l...@cbvox1.att.com
#How about a net effect of ZERO! The military did all sorts of
#experiments on people and equipment back in the 40's and 50's by going
#out in the desert and detonating nuclear devices with troops out there
#too.
This bring up something I've been wondering about. Have the guns
carried by the troops in these tests ever been sold as surplus ?
"My, your M1 Garand has a nice glow" ;-) Or would it not matter ?
What about surplus guns from Russia, China, or elsewhere ?
--
Larry Cipriani -- l.v.ci...@att.com or attmail!lcipriani
The United States of America, 1776 to 1992, Rest In Peace
ra...@ihlpm.att.com
|reradiate any energy detectable by radar sets. It is a REFLECTOR. It
|would be the same as dropping highly polished tin foil (chaff) into the
|beam of a spot light. You'd see all sorts of bright flashes out in the
|night.
I don't think so; modern chaff as far as I know consists of metalised
glass fibers that are dipoles cut for the frequency of the radar that
it is intended to use against. Perhaps during WW II where they used
relatively low frequencies your statement on chaff as a reflector
might be legitimate, but, I am pretty sure it isn't with today's microwave
radar systems.
dave pierson
#|You also have a misconception about chaff and radar. Chaff does NOT
#|reradiate any energy detectable by radar sets.
Yes it does. Thats how it works.
#> It is a REFLECTOR.
Right.
#It would be the same as dropping highly polished tin foil (chaff) into the
#|beam of a spot light. You'd see all sorts of bright flashes out in the
#|night.
Right.
And the energy leaves the chaff by _radiation_. Its excited by the
incoming field and _radiates_ a portion of that back. There is no
difference, except that the transmitter is powered by an external
source. The chaff is powered by the incoming beam.
thanks
dave pierson |the facts, as accurately as i can manage,
Digital Equipment Corporation |the opinions, my own.
200 Forest St |I am the NRA.
Marlboro, Mass 01752 USA pie...@msd26.enet.dec.com
"He has read everything, and, to his credit, written nothing." A J Raffles
Ad absurdum per aspera
#carried by the troops in these tests ever been sold as surplus ?
#"My, your M1 Garand has a nice glow" ;-) Or would it not matter ?
#What about surplus guns from Russia, China, or elsewhere ?
So THAT'S where all the gummy stuff on my old Chinese SKS came from!
I should throw my badge in with the guns for a few weeks and see if
it turns up anything besides its customary 0.00.
Seriously, I can't imagine that a neutron flux sufficient to activate
steel to any significant degree in such a brief pulse would have been
very good for the troops carrying the weapons.
Decontamination of hard, smooth, non-absorbent items contaminated
by fallout is a relatively simple matter. One would hope they'd
have done it for their own protection, so as not to have radio-nasties
in the arsenal, but you never know. There *have* been incidents of
"troops are cheap and radiation is mysterious" even here in the US.
At any rate, although these tests were a big deal to the soldiers
and sailors involved, few were involved. The odds of getting an
activated or contaminated surplus weapon are pretty small. I'd
say that headspace, hidden corrosion, crappy rewelds, deformed
barrels, etc. would be much bigger risks than radiation, so if
your gunsmith doesn't have a Geiger counter, don't worry.
--Joe
"Just another personal opinion from the People's Republic of Berkeley"
Disclaimer: Even if my employer had a position on the subject,
I probably wouldn't be the one stating it on their behalf.
Thorick Chow
#I guess I'm a bit confused by the possible effects of EMP on ammunition;
I don't have any real experience in this, but seems to me that the
'insulating' property of the Faraday Cage would only be perfect
in the electrostatic case and becomes less perfect as the
electrostatic case is departed from (?)
If this is true, then an immensely (sp) strong and wild pulse
would probably excite things enough to transfer enough
energy to cause ignition...
????
-t.c.
Gary Coffman
#
##I guess I'm a bit confused by the possible effects of EMP on ammunition;
#since the shell of the smallarm round is itself a Faraday cage, and since
#the shell itself would reradiate EM radiation, one presumes like metal
#chaff used against radar, can there be much radiation that would be
#ansorbed and somehow converted to heat?
#
#I don't have any real experience in this, but seems to me that the
#'insulating' property of the Faraday Cage would only be perfect
#in the electrostatic case and becomes less perfect as the
#electrostatic case is departed from (?)
#
#If this is true, then an immensely (sp) strong and wild pulse
#would probably excite things enough to transfer enough
#energy to cause ignition...
#????
Ok, let's look at this in a bit more detail. What we're concerned about
is a current flow through the primer strong enough to cause the primer
to fire. To do this we have to generate a strong enough potential field
across the length of the case to cause a strong current to flow in the
case material. EMP would do this by H field induction. Now here's the rub,
and why we can forget EMP firing ammo, the H field has to be significantly
different across the dimension of the case in order to induce that strong
current flow. That implies an EM field with a wavelength no more than
4 times the length of the cartridge, or a wavelength of about 1 foot.
That's a frequency of about 980 MHz. Since EMP energy is determined by
the area under the discharge curve for a given frequency, and most of
that area falls in the region under 2 MHz, this isn't a realistic problem.
EMP is primarily a consideration for conductors of lengths around 37.5
meters or longer. Incidentally, that's why VHF/UHF radios survive EMP
while HF radios do not. The antennas are too short to pick up sufficient
energy from the pulse.
Gary
--
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