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Re: [Phys-l] EMP hardening




On 2011, Mar 28, , at 13:48, John Denker wrote:

On 2011, Mar 28, , at 11:00, trappe@physics.utexas.edu wrote:

The helicopters may be leaving to protect their navigation
electronics from radiation damage. Some bombers maintain a
redundancy using old ferrite core memory from the 60's.
Supposedly this was a lesson learned in WWII electronics.

On 03/28/2011 12:24 PM, Bernard Cleyet wrote:

There's a movie based on the discovery of tube based electronics in
a soviet fighter "collected". It took a while for the CIA, whoever,
to realize the Soviets were not backwards!

I heard that story decades ago. I didn't believe it then, and
I don't believe it now. Sometimes things that look backward
really are backward. The disadvantage of tubes far outweigh
the advantages, and have for a very long time (except for a few
niche applications such as klystrons and ignitrons).


The capabilities of the MiG-25 were better understood in 1976 when Soviet pilot Viktor Belenko defected in a MiG-25 to the United States via Japan. Production of the MiG-25 series ended in 1984 after completion of 1,190 aircraft. The MiG-25 flew with a number of Soviet allies and former Soviet republics and it remains in limited service in Russia and several other nations. It remains the fastest combat aircraft ever produced.


http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25



This is 1976.

Note the arguments for using an aging technology:


• The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Although they represented aging technology, vacuum tubes were more tolerant of temperature extremes, thereby removing the need for providing complex environmental controls inside the avionics bays. In addition, the vacuum tubes were easy to replace in remote northern airfields where sophisticated transistor parts might not have been readily available. Thanks to the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name "Foxfire") radar had enormous power – about 600 kilowatts. As with most Soviet aircraft, the MiG-25 was designed to be as rugged as possible. The use of vacuum tubes also makes the aircraft's systems more resistant to an electromagnetic pulse, for example after a nuclear blast.[16]
[edit]Later versions
As the result of Belenko's defection and the compromise of the MiG-25P's radar and missile systems, beginning in 1976, the Soviets started to develop an advanced version, the MiG-25PD ("Foxbat-E").[5] This upgrade consisted of new RP-25 Sapfeer/ Saphir look-down/shoot-down radar, infrared search and track (IRST) system, other electronic improvements and more powerful R15B-300 engines. About 370 earlier MiG-25Ps were converted to this standard and redesignated MiG-25PDS.


http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25






EMP is not magic.

The sorts of things you need to do to protect against EMP are the
things you ought to be doing anyway, as standard good practice,
because they protect against interference from lightning strikes,
nearby radio transmitters, et cetera.

For long-haul data, replacing wires with optical fibers is a huge
win. That wasn't an option in the 1960s, but it is now.

To be sure, there are plenty of people who don't understand this
stuff ... but that doesn't mean it cannot be understood. It's
just physics ... if you do the physics right:
-- Maxwell equations, yes.
-- Kirchhoff's laws, no. Interference processes violate Kirchhoff's
laws in a big way.



http://en.wikipedia.org/wiki/Electromagnetic_pulse

bc remembers discussing the Hi test in an E & M class taught by a UCB prof. involved with it, and does not slavishly believe wikipedia.