Richard Clark wrote:

"Basis" is not another engineering term for magnitude. What was
astonishing through nuclear detonation was corralled and managed into
an e-bomb, which is nothing more remarkable than clever engineering of
shorting a capacitor. Each of the three could be cleverly induced to
give the same RF signature - what price "basis?" It happens a
trillion times a day with all the microwaves ovens on this earth.

73's
Richard Clark, KB7QHC

Richard

To see you write that the "clever engineering of shorting a capacitor"
is remotely similar to standing in front of a microwave oven is very
disappointing to say the least. You are losing your edge.

You know very well that they aren't remotely similar in the effects
produced. For one thing the "clever engineering of shorting a
capacitor" is very misleading without at least some explanation of how
different it is from simply shorting a capacitor.

tom
K0TAR

On Tue, 06 Oct 2009 21:52:46 -0500, tom wrote:

To see you write that the "clever engineering of shorting a capacitor"
is remotely similar to standing in front of a microwave oven is very
disappointing to say the least. You are losing your edge.

You know very well that they aren't remotely similar in the effects
produced. For one thing the "clever engineering of shorting a
capacitor" is very misleading without at least some explanation of how
different it is from simply shorting a capacitor.

Hi Tom,

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

On Tue, 06 Oct 2009 23:08:33 -0700, Richard Clark
wrote:

The trigger device often employs a charge driven
shorting bar.

Charge here means explosive charge (accelerating the shorting bar into
the capacitor).

It is only a matter of capacitance and low resistance
metalurgy from there.

The capacitor is called a Marx bank (some cold-war irony there) in a
Explosively Pumped Flux Compression Generator. There are issues of
self shorting inductors wound around cylindrical explosive charges and
reams of discussion which all basically devolves to very simple and
fundamental LC with peak IR relationships.

How could it be otherwise?

73's
Richard Clark, KB7QHC

Richard Clark wrote:


The capacitor is called a Marx bank (some cold-war irony there) in a
Explosively Pumped Flux Compression Generator. There are issues of
self shorting inductors wound around cylindrical explosive charges and
reams of discussion which all basically devolves to very simple and
fundamental LC with peak IR relationships.

Erwin Marx of the eponymous Marx bank has no connection to the Marx of
political theory. Marx published his papers describing the design of
his impulse generator in the teens or twenties, as I recall.


Flux compression generators are different. I suppose one could use a
FCG to charge a Marx bank, which would self erect, but I don't know that
would buy much in a weapons context.

The discharge time of a Marx is limited by the stage
capacitance/inductance. The fact that you stack a bunch in series helps
reduce the C, but the series L and R exactly counteracts it. The big
advantage is that once you get outside the generator, higher voltage
lets you have higher di/dt on the rest of the circuit, but that presumes
the rise time of the Marx is faster than the limit imposed by the load
R/L/C.

There are better ways to make very fast high voltage pulses, if that's
your goal. Fruengel's books on "pulse discharge" provide a plethora of
ideas.

Ultimately, the limit is the propagation speed in the conductors (so
schemes using transmission lines are popular: Blumlein published one in
the 40s(?) that's used a lot)

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.

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.

On Thu, 08 Oct 2009 10:19:47 -0700, Jim Lux
wrote:

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)

Hi Jim,

Actually, a nuclear detonation propagates three forms of EMP. We both
discussed the fastest which correlates to discussions ongoing here in
the 1GHz and higher spectrum.

I will leave it to Art to wonder of the mysteries of an atom bomb
pushing aside magnetic field lines (what? no equilibrium?) for the
slowest pulse. For purposes of Focusing this EMP pulse he has his
shoebox sized 160M dipole/reflector technology to fall back on.
Perhaps he might consider a nuclear hand grenade. I would love to see
a youtube video of him pulling that pin and tossing it into the
reflector.

73's
Richard Clark, KB7QHC