EMP CSC 1984 SUBJECT AREA C4 EMP Submitted To Mr. Wiggins In Partial Fulfillment of Requirements for Written Communications The Marine Corps Command and Staff College Quantico, Virginia Major R. D. Erick United States Marine Corps April 6, 1984 EMP! Outline Thesis sentence: EMP is a very misunderstood force that will have a devastating effect in a tactical nuclear war. I. How EMP was noticed II. Factors that determine EMP A. Formation of EMP wave B. Strength of EMP wave 1. Low-level blasts 2. Surface blasts 3. High-altitude blasts III. Tactical warfare (low-level or surface blasts) A. Present stock of tactical nuclear weapons B. Vulnerability of our tactical systems C. Vulnerability of the Marine Corps systems D. Vulnerability of Soviet tactical systems IV. Protecting against EMP EMP! EMP. What is it and how will it affect us in a tactical nuclear war? EMP stands for Electromagnetic Pulse. Explosions of conventional high explosive bombs produce EMP. However, the effects produced by a nuclear explosion were not fully realized until the "Johnston Is- land Test" in 1962. This nuclear blast had a yield of 1.4 megatons at an altitude of 250 miles. The explosion damaged a number of low earth orbit satellites and caused malfunctions and early failure of others. Another effect that was noted during the blast was a black- out up to 600 miles away of high frequency radio communications that lasted for hours. It was caused by disruption of the ionosphere. It also popped circuit breakers, street lights went out, burglar alarms rang, and power lines went down in Honolulu, about 800 miles away. In Nov. 1962, all above ground testing was halted and our testing and analysis was limited to underground testing, analysis of the existing atmospheric test data, nonnuclear simulation, and theoretical calcula- tions. This is in part why we know so little about the effects of EMP. The primary effects of a nuclear blast are the blast, thermal, and radiation. This is where the propensity of effort was put in the early years. Although most of the information on this subject is classified as far as what our vulnerabilities are and what we have hardened and what we are doing to solve the problems, all the information contained in this report is unclassified and can be discussed freely. Electromagnetic Pulse, or EMP as we will call it through out the rest of our discussion is not a unique phenomenon. There are a variety of factors that determine EMP. However, the first phase is always the same, a form of energy released by means of a nuclear detonation. This causes gamma rays to collide with air molecules. Electrons are given off by the air molecules and the motion is transfered from the gamma rays to the free electrons. The result is a scattering of these neg- atively charged electrons and the positive air molecules are left be- hind. See figure 1. Click here to view image Reaching its maximum strength the electric field strength falls off and becomes quite small in a few tenths of a microsecond. Despite the relatively short duration of this pulse it has a considerable amount of energy and it travels away from the blast point at the speed of light. The next phase of generation is dependent on whether the blast is a low-altitude air blast, a near-surface or ground blast, or a high- altitude blast. The low-altitude air blast is usually described as from three to 19 miles above the earth's surface. See figure 3. Click here to view image This type of blast is probably the least destructive as far as EMP is concerned. It's effects will generally range from three to nine miles depending on the height of the blast point. Even though our modern day systems can survive the blast, thermal and overpressure effects at these distances, EMP could induce operational problems such as burn out of circuits, erasure of memory and recorded data. The EMP of a low-altitude blast, even though covering more area is less intense than in a surface blast. The surface blast is the most devastating as far as the tactical Click here to view image Since the ground is a relatively good conductor of electricity it provides an alternative path for the electrons. The electric currents thus flow in the ground and generate strong magnetic fields in the re- gion of the surface blast point. The electric field produced in this surface blast is very strong but the radiated field falls off with in- creasing distance much the same as the low-altitude blast. The poten- tial hazard to electrical and electronic equipment from the EMP will be greatest within the disposition region which may extend over a radius around ground zero out to 10 miles. This is dependent on explosion yield. High-altitude blasts, above about 19 miles, have two kinds of ef- fects. First is the gamma rays that move upward from the blast point because of the low air density at the heights. These gamma rays travel great distances before they are absorbed. This affect can cause great damage to satellites since the range of travel of these gamma rays can be hundreds of miles. See figure 5. Click here to view image The other effect of high altitude explosions is that the gamma rays emitted are generally downward so as to encounter a region where the atmospheric density is increased. These gamma rays collide with the air molecules as previously mentioned to create a source region for the EMP. This region can be up to 50 miles thick and several hundred miles in diameter. This causes an EMP that generally moves down toward the earth's surface. The EMP strength of a high-altitude explosion is from 1/10 to 1/100 of that of the surface blast. However, the surface blast's strength drops off rapidly with distance. The effects of the high al- titude blast at 200 miles above the center of the United States could cover all of the United States and parts of Mexico and Canada. On the tactical battlefield we will probably not see the high altitude nuclear blast. This will be used by the Soviet Union as the first step in the escalation from tactical nuclear weapons to a stra- tegic nuclear war. The effects of this, while being able to knock out some of our communication satellites and thus disrupting communications from the battlefield back to the President or Joint Chiefs of Staff, sould have none of the tactical effect or influence in that it would knock out all the communications in the United States and would cause massive failures in systems not hardened against EMP. The system of greatest interest for the Soviet Union would be the Command and Control Network which would disrupt communications and launch commands to our strategic nuclear missiles. It also could disrupt the computer systems that control these nuclear missiles. Other effects would be to disrupt the life of the average American citizen by causing massive black outs, disrupting all radio and television communications and the Civil De- fense network. If we go from peacetime directly into an all out nuclear war we will never use a tactical nuclear weapon. However, the United States and the Soviet Union were until several months ago engaged in two sets of nuclear arms talks, one dealing with the intercontinental range stra- tegic weapons, and the other dealing with intermediate range strategic weapons. Both of these talks have since been suspended. However, there is a very large armory of nuclear weapons which the U.S. and the U.S.S.R. have not begun to talk about. These are the approximately 8,000, 20 to 1,000 Kiloton range tactical nuclear weapons held by both super powers not to mention those held by third world countries which may not even have a strategic capability. Because of the lack of limitations on these tactical weapons I will be looking at the tactical effects of EMP on our equipment and the way we fight wars. Both the low-altitude and the surface blast will probably be used on the modern tactical battlefield. The low-altitude nuclear blast has a very small zone of effect and in almost all cases when talking about nuclear weapons in the kiloton range, the other effects such as blast, radiation, overpressure and thermal far outweigh the damage caused by EMP. I will concentrate on the surface blast for the rest of the paper since it has the greatest potential for causing us problems with EMP at a tactical level. As stated previously the EMP is an actual pulse form in the time domain with peak value and pulse slope characteristics as see in figure 2. One of the biggest problems of EMP is that it creates a pulse, which may be up to 40 kilovolts per meter and is 50 times faster than lightn- ing. This means that normal lightning protection is ineffective. The nature of the problem is that the voltage pulse arising from the EMP rises to kilovolts in one billionth of a second and currents in the kilo- amp range.A typical surge arrestor such as used to protect electronic equipment from lightning can not react this fast to the rise in voltage nor can it handle the current demands. The EMP is induced into the elec- tronic equipment the same as lightning or electromagnetic waves but with greater intensity and over a broader spectrum. In other words, instead of a very narrow band such as a radio signal which is a specific fre- quency or lightning which affects a fairly narrow frequency range, EMP affects a very broad band. Any conducting objects such as metal ob- jects exposed to the EMP act as collectors or as an antenna even though it is not intended to be one. Generally, the larger the metal object the greater the amount of energy that is induced into the system. This is the difference between radiation and EMP. For other nuclear radia- tions, such as blast, thermal, and overpressure the energy is only on the exterior of the structures. The EMP effects are collected and can be conducted into a metal structure by wires which focus a large amount of energy to the interior of the system. The equipment reacts by treat- ing the EMP as noise. The collectors would be not only those items specifically designed to be antennas but also items such as cables, gun tubes, missiles, structural members, guy wires, conduction loops, and even railroad tracks, fences and metal sheets. There are two kinds of damage EMP can cause to electrical or elect- ronic systems. First is the actual physical damage caused by electrical components shorting out or burning out such as capacitors, resistors, and transistors, thus causing the repair or replacement of the component. The second is of lesser concern because it causes only temporary oper- ational upsets such as instabilities, causing the system to shut itself down, upset computers so they must be started again. Both these effects increase in direct proportion to the amount of digital technology and the large scale integrated circuitry designed into our systems. Items such as motors, power switches, and components that are subject to large power levels in normal use are relatively uneffected by EMP. Both sides in a nuclear war are vulnerable to EMP. However, the U.S. will probably be more vulnerable because of our greater sophistication in transistors and miniature and micro circuits. We have made everything smaller by the use of solid state circuits. Yet, this technoloty is particularly vulnerable to EMP because of its small size and micro geometry. The Marine Corps in particular will have problems with the EMP. The battlefield will be extremely difficult to operate in and if tac- tical nuclear weapons are employed by the opposing forces the situation will be even more complicated by the effects of EMP. The command and control systems will be knocked out. The generals and their staff will not be able to talk to their front line troops and they will not be able to receive instructions from higher headquarters in the United States. Not only will the communications be disrupted but any equipment which has integrated circuits or transistors will be affected. This will include such equipment as generators, aircraft electronics systems and ground electronics systems. Because of our increasing technology, we have made ourselves even more vulnerable in this area. For example, all our new family of vehicles which have electronic ignition and com- puter controlled ignition advance and computer controlled fuel-air mixture will cease to operate. Not only will we not be able to talk on the tactical nuclear battlefield we might not even be able to move. The Soviets, however, have not yet replaced many of their vacuum tubes with solid state devices. Vacuum tubes are far more resistant to EMP that the microelectronic devices. This was emphasised when one of the Soviet's most modern jet fighter, a MIG -25, was flown to Japan by a Soviet defector in 1976. Subsequent investigation revealed that this modern fighter used vacuum tube electronics extensively. It should be mentioned that even though this modern jet had vacuum tubes it may be that this is more directly related to the lack of Soviet Union's semi- conductor technology than to any attempt by the Soviets to harden their aircraft against the effects of EMP. As put by Daniel L. Stein, assistant professor of physics at Princeton, " a ground or low-altitude burst generates significant elec- tromagnetic pulse out to distances corresponding to an overpressure of about two pounds per square inch, the radius of blast damage to resi- dences - approximately seven - to - ten miles for a one megaton weapon. A sophisticated system hardened against blast, thermal and over-pressure effects of a low-yield weapon could well suffer operational upset, such as, erasure of memory or recorded data, from electromagnetic pulse. Disruption of communications and coordination among tactical aircraft may occure, and their links to a central authority may be temporarily broken." 1 The big problem is that the next war could be characterized by this EMP phenomenon which our armed forces have never before experienced in combat. When it first happens we need to know what we as the forces on the ground or in the air can do to protect the equipment we have. We also need to make more people aware of the problem so we can develope new equipment and weapons that will minimise the effects of EMP. It is easy to say we can protect against EMP in principle but very difficult to implement and even more difficult to maintain. There are two basic methods of providing EMP protection. The first is to provide a shield which will not allow the EMP to enter. The second is to design and build the equipment so that the circuit can resist the EMP. Often the most cost effective way is to use a combination of both methods to de- feat the EMP. We will look at a few ways to defeat the EMP which are for the most part combinations of the two basic ways. Features that need to be designed in are such things as pulse resistant fiber optics, improved power supply systems using batteries, solar power and thermo- nuclear power sources, and the use of nodule self-healing network architec- ture. In the case of computer memory we need to insure that magnetic tape or some other semipermanent storage device used to store data and programs for the computer. The operator can do little to harden his equipment to EMP but he can do some things that might help lessen the damage to the equipment. First the equipment should be operated and maintained by the technical manuals. All equipment access doors should be kept closed. Cables should be buried under steel sheets to a depth of three feet. Use the shortest possible cables and disconnect them when not in use. Keep equipment away from large collectors such as long cable/power lines, fencing or railroads. Even though some individual components or circuits may be tested it is often difficult if not impossible to predict how the entire in- tegrated system will react to an actual nuclear explosion. We have seen some movement toward hardening systems in the last few years but effective hardening of entire systems is simply impossible and not cost effective. The Joint Chief of Staff last year asked for 7 billion dollars to upgrade command and control. Only part was spent on the electromagnetic pulse protection and even less was spent on tactical systems. In general the understanding of EMP, the means to harden, and the technological capabilities are all present to make our system survivable. The problem is to make people aware of the EMP phenomena and get the funds to do the work. Not only do funds need to be made available but there are other considerations such as the problem of hardening the President's E-4B National Airborne Emergency Command Post. It costs not only dollars but close to 14,000 pounds in added weight to harden the aircraft as compared to the unhardened aircraft. Finally, it was stated by Captain Jay Willis, who has a master of science in nuclear engineering, "One question that is easy to answer is whether any given air defense system" or any tactical system, "may re- asonably expect to be subjected to an EMP in a nuclear war. A single thermonuclear detonation at an altitude of a few hundred kilometers can blanket an entire theater of war with a strong EMP. EMP could damage any of our military or critical civilian electrical systems or elec- tronic equipment. Any potential nuclear advesary probably would not hesitate to make full use of EMP against our forces."2 FOOTNOTES 1Daniel L. Stein, "Electromagnetic pulse - The uncertain certainty. The Bulletin of the Atomic Scientists, Mar 83, p. 54. 2Captain Jay C. Willis, "EMP: An Increasingly Important Nuclear Weapons Effect. Air Defense Magazine, Jan - Mar 82, p.16. Bibliography Brannon, Phil. "Short Circuiting EMP." Journal of Electronic Defense, (April 1983), 20. Cook, K. G. "Fast Gas Filled Surge Arresters for EMP Protection." Journal of Electronic Defense, (August 1982), 49 - 54. Dean, Johathan. "Battlefield Nuclear Weapons." Arms Control Today, (September 1983), 5 - 9. Dolan, Philip J. and Samuel Glasstone. The Effects of Nuclear Weapons. 3rd ed. US Department of Defense and the US Department of Energy, 1977. The Effects of Nuclear War. OTA Congress of the United States, Office of Technology Assessment, Washington, D.C. Lippert, Jorg C. "The Hidden Destroyer." NATO's Sixteen Nations, (April, May 1983). McQuade, K. F. "Improved C3I Systems Needed for Survivability." Defense Electronics, (August 1983). 60. Schemmer, Benjamin F. "Fastest Growing Part of DOD Budget: 'Electronic Defense' - Real Growth of Over 10% a year for C3 Programs Alone." Armed Forces Journal International, (February 1983) 26 - 27. Stein, Daniel L. "Electromagnetic Pulse - The Uncertain Certainty." The Bulletin of the Atomic Scientists, (March 1983) 52 - 56. Steinbruner, John. "Launch under Attack." Scientific American, (January 1984), 37 - 47. Ulsamer, Edgar. "The Mass Media Discover EMP." Air Force Magazine, (April 1983), 17 - 18. Willis, Jay C. "EMP: An increasingly Important Nuclear Weapons Effect." Air Defense Magazine, (January - March 1982), 12 - 16.
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