HEMP is a well-known transient EM threat that is generated when a high-altitude nuclear burst is detonated at an altitude about 20 km or more. A nuclear burst at these altitudes will have no direct radiation impact on people on the ground; however, electronic systems within 1000 km or more may be damaged or affected in such a way that they may not operate properly.

IEMI is a term that describes the use of non-nuclear electromagnetic weapons to disable nearby electronic equipment. Due to developments in source technology, it is possible to produce severe electromagnetic fields, currents and/or voltages at distances of tens of meters from a suitcase-sized device that could disable (upset or damage) civil electronic equipment. This could be done for criminal or terrorist reasons.

DGI personnel have wide-ranging experience in HEMP and IEMI. As an example, a DGI employee is a member of the Congressionally-mandated EMP Commission that is investigating the effects of HEMP on civilian electrical/electronic infrastructure and on military systems.

DGI has also been instrumental in these additional EM activities:

• Preparation of reports, briefings and a tutorial on all aspects of HEMP and IEMI, including analysis, simulation and testing, for the US Government.
• Studies, including experiments, on the EM pulses caused by detonations of conventional munitions. This could lead to development of techniques in which EM pulses can be used to determine the location of a detonation.
• Analyses of the vulnerability of electromagnetic/electrical systems to HEMP and IEMI, as well as the hardening of facilities to these environments.