Richard Clark wrote:

EMP is a fast charge/discharge event. EMP products come in three
flavors, I will only discuss the fastest. The fastest is rarely
described with a risetime less than 1nS, but I have seen others bandy
about the frequency of 10GHz, so we have to assume they have links to
literature that claim a risetime on the order of 33pS. Be that as it
may, mercury switches can switch a 1000V pulse into a 50Ohm load in
500ps. This is laboratory stuff, not armament. Armament can be
engineered to perform with larger supplies as one-shot disposable
switches (you don't run lab equipment to failure, new out of the box
on the first application of power). Such switches are controlled
access and limited sale items.

To generate this 10GHz pulse would require very, very short very, very
low resistance leads; which would, of course, become part of a tuned
(to 10GHz) circuit. The trigger device often employs a charge driven
shorting bar. It is only a matter of capacitance and low resistance
metalurgy from there.

73's
Richard Clark, KB7QHC

One might want to distinguish between EMP from, e.g. a nuclear device,
which is a fast pulse (the rise time of which is fundamentally limited
by the size of the fireball.. EM energy from the far side takes longer
to get to you than the near side)

AND

EM weapons designed to create damage similar to that from EMP.

Those are usually high peak power microwave sources with moderately long
pulses, designed to put enough energy into the victim to cause the damage.


There is also, the much talked about and demonstrated broadband pulse
generator schemes... some sort of fast discharge into a broadband
antenna (often a bowtie).. You see these demonstrated as built into an
attache case. Put the briefcase EMP generator next to the victim
electronics, trigger the bang, look! dead PC.

This is typically a few hundred joules with a low inductance pulse cap
charged to a few kV or 10s of kV, discharging through a triggered spark
gap.

Ground Pulse Radar does a very similar thing (with better calibration,
lower powers, etc.)


This thing is used to encourage funding of countermeasures or funding of
"bigger and better" versions, particularly in front of folks who don't
understand things like inverse square law.