Non-nuclear Electromagnetic Pulse Generation

My Dark Angel Science Page and the main Futurescience EMP Page have both prompted some questions about non-nuclear means of generating EMP over a very limited area.  I am certainly not an expert in this subject, and I won't be telling any potential vandals or terrorists anything that they can't very easily find out elsewhere.  I am an electronics engineer, though, who has spent most of my career working with high-power transmitters, so I do know that generating a very-limited-area EMP is much easier than most people realize.  Plans and devices are available on the internet.  There are good Wikipedia articles about some of the basic devices.

No one should try experimenting with any of this stuff without the appropriate knowledge of the safety issues involved.  Working close to the equipment described here can be quite dangerous for humans who are not knowledgeable about working with high voltages and high power circuitry, and (as should be quite obvious) this equipment can be damaging to electronics equipment in the areas surrounding the device.

Governments have long been interested in small EMP weapons.  In April, 2008, the English language online version of Pravda, briefly described some of what Russia is doing in this article with a photo of one of the devices.

It is difficult to categorize many of these devices because there is often a lot of similarity among these categories.   Basically, though, these devices include:

Flux Compression Generators.  These devices have been around for a long time (at least since 1951), and they can be made in many different ways.  A lot of formerly classified information about them has been declassified.   For example, see this technical introduction to flux compression generators from Los Alamos.  Flux compression generators are the most commonly discussed type of non-nuclear EMP weapon.  They can range in size from large and powerful military weapons to much smaller devices that can be carried in a small truck or van.  Most of them are detonated with explosives, but very small ones could use compressed air, especially for preliminary testing.

The Electromagnetic Pinch Device is most often used to demonstrate the electromagnetically induced crushing of common objects such as cans and coins, as shown on the Captured Lightning site  (which also has a lot of other information related to this general topic).  A pinch device can direct a large amount of electromagnetic energy at an object in the distance if, for example, the electromagnetic discharge of the device is placed at the focus of a parabolic dish.

The Marx Generator has been around since 1924.  It has much in common with voltage multiplier circuits that were common in power supplies in the old vacuum tube days.  Marx Generators are often used in EMP simulators for testing how resistant equipment is to EMP.

One of the simplest EMP generators is simply a pulsed high-power radio transmitter.  This is the principle behind the HERF gun, a High Energy Radio Frequency weapon that has been proposed for uses such as stopping vehicles by disabling their electronic ignitions.  Some companies have tried to sell small hand-held microwave HERF guns to police departments for disabling the vehicles of criminals.  Police departments seem to be wisely resisting the use of HERF guns in the belief that as soon as these things go into mass production, they can be illicitly obtained by other individuals for doing all kinds of electronic vandalism and mischief.

An example of a non-nuclear EMP device is the one being marketed by Eureka Aerospace, which is described, with a video, at the Physorg site.  These devices are designed to destroy the vital electronics in automobiles.  Although these devices can be beneficial in many cases, in the wrong hands they could cause enormous destruction at the rate of millions of dollars in damage per hour.

The problem is that these pulsed high-power transmitters are rather easy for anyone with any degree of electronics expertise to make.  All that is required is to make a high-powered radio transmitter, without having to be concerned with the problems of getting rid of excess heat or of producing sustained amounts of high DC power levels.  If a person only wants to obtain an extremely large amount of radio frequency energy for less than a millisecond, then the problem is rather trivial compared to the problem of creating a sustained high-power signal.

For generating single high-power pulses, you don't need a high-wattage power supply at all.  One can simply charge a large capacitor to a high voltage, and discharge the capacitor through the DC input of the high-power transmitter in order to obtain the pulse.  Conventional highly-directional antennas can be used to direct the energy to the desired location.  In most cases, the voltage, current, and power ratings of the equipment can be exceeded -- sometimes by a very large amount -- for a millisecond or so, in order to obtain a radio-frequency pulse of incredibly high power.

After full-power analog television broadcasting came to an end in the United States on June 12, 2009, a large number of high-power transmitters went out of service.   All of these transmitters have high-power transmitting cavities that can easily be turned into an extremely high-energy EMP generator.

Many hobbyists have used this high-energy RF principle to turn a microwave oven into a small directed energy weapon.  A microwave oven is basically just a high-power microwave transmitter that dumps its energy into a faraday cage (used for the cooking chamber) instead of into an antenna.  I am amazed that no one has been seriously burned when trying this, since it can be quite dangerous if extreme safety measures are not used.  All electromagnetic weapons are weapons, and are capable of causing electrocution and severe burns near the equipment, although the electromagnetic pulses themselves are usually harmless to humans.

Examples of some small high-energy radio frequency pulse generators can be found at this site that sells devices and plans, and that also rents some of the more sophisticated devices to researchers.   (I have no affiliation with that site -- or any other sites mentioned on this page -- except for the Dark Angel Science page and the other pages.)

Another site that sells electromagnetic pulse generators that will cover a small area with an extremely strong pulse is Applied Physical Electronics, L.C.

All of the non-nuclear means of EMP generation have an extremely limited range compared with any form of nuclear EMP, especially high-altitude nuclear EMP.  A terrible cover story in the September 2001 issue of Popular Mechanics magazine seems to have confused many people about this fact.  That article mixed in statements about nuclear EMP and non-nuclear EMP within the same paragraph, making the overall article into a horrible amount of nonsense.  Most of the individual sentences in that 2001 article were correct, but the odd juxaposition of statements about nuclear and non-nuclear EMP made it into one of the worst science articles published in recent years.

There are undoubtedly classified non-nuclear EMP weapons that are derivatives of the 60-year-old flux compression generator that are possessed by governments for use in warfare.  Although these weapons probably have great usefulness in certain types of combat, they are unlikely to possess any great threat to civilian infrastructure beyond the threat posed by other conventional weapons.

Video games and fanciful Hollywood weapons have added to the confusion about non-nuclear EMP.  Those who make their living disparaging EMP have further added to the confusion with claims that non-nuclear EMP devices must obey the inverse-square law.  As I have pointed out elsewhere, this misunderstanding of the inverse-square law could be used to prove that radio and television broadcasting is only effective very close to the transmitting site, when we all know that this is not the case.

The inverse-square law applies to total energy levels, and not to electric field strength.  The electric field strength generally falls off linearly with distance from any electromagnetic source.  This is what makes radio and television broadcasting possible.

Most of the damage from any electromagnetic pulse weapon will be proportional to the electrical field strength, and not the total energy level.

Nevertheless, non-nuclear EMP weapons are mostly a threat from terrorists and vandals.  They could do a terrible amount of electronic damage if detonated just outside of a facility with important electronic equipment inside.  They do not have anything close to the widespread damage that could be caused by high-altitude nuclear EMP, which is a very unique kind of phenomenon.

This page is written by Jerry Emanuelson.

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