[R-390] EMP

Fri Sep 25 23:16:21 EDT 2009

Just to reiterate a bit on my experiments. My " fireball" is a best a few mm in diameter- compared to a km for a real one. The energy of the EMP pulse scales with the volume of the fireball- so a real EMP pulse would be 10 ^ 27 times more energetic than my lab experiments. The energy of the EMP is dependent solely on the number of electrons in the fireball volume. Also the duration of the EMP pulse scales with the diameter of the fireball- so my nanosecond laboratory pulse becomes a millisecond pulse for a real one.  Probably 10's of % of the total yield of a nuke appears as an EMP pulse.

I was privileged to work for Prof. Hans Bethe ( he was the head of the theory division at Los Alamos during the Manhattan Project) back in the 60's when he risked ( and lost) his security clearance for revealing the nature of EMP effects from nuclear weapons. He gave a seminar at Cornell University in the late 60's declassifying EMP effects and then published an article in Scientific American about EMP effects- very good reading.

Shielding from EMP is possible- you just have to shield both the E field and the H field- and keep the H field shield from saturating- multi-layer mu-metal foils work interleaved with copper sheeting and dielectric insulation. I have designed shields that work for 1-5 Tesla RF fields and kept sensitive electronics alive! 

Usually for an EMP event you will be in the far field of the event ( if you were in the near-field the blast and radiation would get you before the EMP). In the far-field- the predominate field will be the E-field- much easier to shield against since there are no saturation effects to consider ( mu is a function of H for all real material- wheras sigma ( conductivity) is a constant for most fields of interest).

Sam  KE5IRZ

> From: dsmaples at comcast.net
> To: chacuff at cableone.net; mikea at mikea.ath.cx; r-390 at mailman.qth.net
> Date: Fri, 25 Sep 2009 20:32:56 -0400
> Subject: Re: [R-390] EMP
> 
> All: Side note: Another book you might want to look for is Alas Babylon.
> Pretty decent portrayal of the events following a late 50s nuke exchange.
> More in the human side of things.
> 
> As far as loss of electric power is concerned, if you want to curl your
> hair, find the report from the EMP Commission on critical infrasctructures
> and read it through. This isn't fiction, but I wish it was.  Page 27 (if I
> remember correctly) contains some very, very sobering information about the
> manufacture of large power transformers used in the grid...as you read it
> think not only EMP but truck bomb or RPG.
> 
> Dave WB4FUR
> 
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of Cecil Acuff
> Sent: Friday, September 25, 2009 8:13 PM
> To: mikea; r-390 at mailman.qth.net
> Subject: Re: [R-390] EMP
> 
> 
> Restore some old but reliable tube transceivers for use after an EMP event.
> Sounds crazy but it's easy to put in a stock of spare tubes and other
> spares.
> 
> After such a life changing event as a nuclear attack even basic
> communications will be a welcome commodity.
> 
> Powering the stuff is the other problem.  Many portable generators use
> solidstate controllers for engine speed regulation and excitation.  Not sure
> those will survive.  Something more vintage will be necessary there as
> well...and that's if the insulation in the windings survive...
> 
> Interesting problem...one I hope we or our kids and kids, kids never have to
> face...
> 
> Cecil...
> ----- Original Message -----
> From: "mikea" <mikea at mikea.ath.cx>
> To: <r-390 at mailman.qth.net>
> Sent: Friday, September 25, 2009 6:38 PM
> Subject: Re: [R-390] EMP
> 
> 
> > On Fri, Sep 25, 2009 at 09:41:12AM -0700, Steve Toth wrote:
> >> So, theorectically, what would be involved in "hardening" a hamshack??
> >> (understanding that the power grid, etc., would be taken out)
> >>
> >> Not being an engineer and having no background in this area, my guess
> >> would be some sort of shielding on all sides of the room, roof and
> >> floor (what would be considered adequate?); thorough grounding of the
> >> shielding and associated equipment (would the lightning strike damage
> >> prevention techniques discussed a little while ago be applicable?);
> >> and filtering of all wiring coming into and out of the room for
> >> excessive voltage pulses??? Or would even those techniques have their
> >> own issues? Just curious.
> >
> > You might get through it with fully-shielded underground vault,
> > containing:
> >
> > A complete set of spare electronics -- as in a complete set of spare
> > transceivers/receivers/transmitters.
> >
> > A complete set of spare cables, connectors, etc., as well, as the
> > voltages induced by all those Compton-effect e- will be big enough to
> > punch through insulation and do other nasties.
> >
> > Filtering just isn't going to do any good against voltage spikes with
> > those magnitudes and such fast risetimes.
> >
> > No, I'm not kidding.
> >
> > --
> > Mike Andrews, W5EGO
> > mikea at mikea.ath.cx
> > Tired old sysadmin
> >
> 
> 
> ----------------------------------------------------------------------------
> ----
> 
> 
> > ______________________________________________________________
> > R-390 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/r-390
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:R-390 at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> 
> 
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> 
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html