HEMP Protection and Verification

High‐altitude nuclear electromagnetic pulse (HEMP) has been recognized as a threat to electrical and electronic equipment since the early 1960s. This chapter describes the phenomenon of HEMP, the effect it has on aircraft, and the methods used for hardening and testing hardened aircraft. An external coupling (EM) wave will induce currents and charges onto the external surface of the aircraft. An aircraft can be in several different EM coupling configurations during its mission: in‐flight, ground alert, in‐flight refueling, or with a trailing wire antenna extended. In a HEMP‐hardened aircraft, the system specification is written in terms of a design margin, which is the ratio of the maximum HEMP‐induced cable currents to the minimum equipment immunity at each cable connector interface. HEMP simulator hardness verification testing is conducted in 3 phases including an active system test, a passive system test, and a direct drive test.