Nominal High-Altitude Electromagnetic Pulse (HEMP) Waveforms

Calculating the characteristics of high-altitude electromagnetic pulses created by the detonation of a nuclear device.

Defense Threat Reduction Agency, Fort Belvoir, Virginia

Even before the Trinity nuclear test in July of 1945, physicists predicted a transient electromagnetic signal would be caused by high-energy photons released from the detonation interacting with the air around the detonation. Predictions of these signals were difficult to make due to the complexity of the physics unleashed by the detonation.

Post-World War II, there was a period of active atmospheric nuclear testing until 1962, during which measurements of these signals were made in order to understand the phenomena that were previously largely viewed as an annoyance and impediment to other instrumentation. The name “electromagnetic pulse” (EMP) began to be used to refer to these signals.