Electromagnetism presents the Defense industry with a wide array of threats ranging from low frequency Electromagnetic Interference (EMI) to High Power Electromagnetism (HPEM), which includes Electromagnetic Pulse (EMP) as well as externally and internally induced transients. While all of these threats are also present in the civilian sector, the integrity of the national defense system requires heightened attention to the importance of shielding against any of these events.
Electromagnetic Pulse (EMP) is an intense electromagnetic field that can instantly overload electrical circuits. Produced in the atmosphere by the power and radiation of a nuclear explosion it is referred to as High-Altitude Electromagnetic Pulse (HEMP) or Nuclear Electromagnetic Pulse (NEMP), which can damage electronic equipment over a wide area. Other sources of EMP include nuclear explosions on the ground, man-made weapons like High Power Microwave (HPM) or Directed Energy Weapons (DEW) as well as natural causes like solar storms. In fact, a solar event producing an E3 pulse could potentially be even more dangerous to the power grid than a nuclear EMP due to the longer duration of the event. According to a report of the National Academy of Sciences, a severe geomagnetic storm could cause economic damage of $1 to $2 trillion in the first year, with 4 to 10 years until full recovery. In a recently published NASA study on severe space weather, scientists concluded that such Carrington-class solar flares occur about once per century. The report warns that a severe flare could occur any time, causing long duration, catastrophic failure of our vital electric infrastructures.
In 2001, Congress established a commission to assess the threat from a large-scale HEMP attack. Several additional studies have since been conducted by the Defense Support Agency (DSA), the Defense Special Weapons Agency (DSWA) as well as the Defense Threat Reduction Agency (DTRA) – all recognizing the realistic existence of an EMP/HEMP threat and the potential long-term disruptive effects.
In the past, the threat of mutually assured destruction provided a lasting deterrent against the exchange of multiple high-yield nuclear warheads. However, worldwide access to newer technologies and the proliferation of nuclear weapons increase concerns about possible EMP/HEMP attacks again. Now even a single, low-yield nuclear explosion high above the United States, or over a battlefield, can produce a large-scale EMP effect without any direct fatalities.
To protect the nation's defense system, the Department of Defense now strictly enforces MIL-STD 188-125, which describes methods for protecting against High-Altitude Electromagnetic Pulse for ground-based mobile and fixed applications.
However, the environmental effects of an EMP/HEMP attack would also expand to the civilian infrastructure. A widespread collapse of the electric power grid could lead to cascading effects on our interdependent infrastructures, possibly lasting weeks or months. Fuel distribution, transportation systems, food and water supplies, communications and other equipment for hospitals and first responders would be affected, thus making any recovery efforts very difficult. As modern electronics shrink in size, circuitry is becoming increasingly smaller and more vulnerable to electromagnetic interference. This further makes repair or recovery of our infrastructure next to impossible.
While the MIL-STD 188-125 class of standards offers guidelines for the protection of critical infrastructure within the defense system, the civilian world has also started to adopt protective measures. The electric power grid is one example of such a civilian application benefiting from EMP hardening. The continuing business need to improve and expand the electric power grid provides an excellent opportunity to simultaneously improve the security and reliability of the system in an economically acceptable manner.
Electromagnetic interference (EMI, also called radio frequency interference or RFI) is a generic term for unwanted interference energies conducted as currents or radiated as electromagnetic fields. When these induced voltages and currents reach levels that disrupt the operation of electronic equipment, it can manifest itself as outright equipment lock-up, software errors, erratic equipment responses, parametric errors, and component damage or sensor misreadings among others.
EMI can also intentionally be used for radio jamming, as in some forms of electronic warfare or lead to Tempest threats, which are unintentional intelligence-bearing signals that can be intercepted and thus compromise defense missions and national security.
Internally and externally generated transients, more commonly known as lightning and surges need not be forgotten in the grand scheme of electromagnetic threats. Not properly protected equipment can easily be damaged leading to downtime or failures that can compromise missions and thus threaten safety and security.