Electromagnetic pulse

There is more information available on this subject at Electromagnetic pulse on the English Wikipedia.

A Is'belox-pattern Banshee when hit by the EMP effect of an overcharged Eos'Mak-pattern plasma pistol.

An electromagnetic pulse (EMP) is the electromagnetic radiation from an explosion (especially a nuclear explosion) or an intensely fluctuating magnetic field caused by Compton-recoil electrons and photoelectrons from photons scattered in the materials of the electronic or explosive device or in a surrounding medium. While organic tissue is unaffected, the resulting electric and magnetic fields may couple with electrical/electronic systems to produce damaging current and voltage surges. The effects are usually not noticeable beyond the blast radius unless the device is nuclear or specifically designed to produce an electromagnetic shockwave. An alternate definition is: a broadband, high-intensity, short-duration burst of electromagnetic energy.

The worst of an electromagnetic pulse generally only lasts for a second, but any unprotected electrical equipment will be affected by the pulse.

Notable examples

There have been several noteworthy instances in which an EMP has appeared.

• The detonation of a nuclear weapon, such as a Shiva-class nuclear missile, is almost always followed by a massive electromagnetic pulse.
• During the Battle of Trove, the smart-AI Serina had Sergeant John Forge use the EMP weapon of several Gremlins to attack the Forerunner pylons attempting to pull the UNSC Spirit of Fire into the shield world known as Trove. As a result, the Spirit of Fire had time to effect a rescue of Alpha, Bravo and Charlie Platoons.
• During the Battle of the Rubble, SPARTAN-II Grey Team used a small EMP device to fry the systems on an Insurrectionist freighter called the Kestrel. This was to wipe its navigation database in accordance with the Cole Protocol which they were at the Rubble enforcing.
• In the aftermath of Operation: UPPER CUT, both SPARTAN-B312 and the satellite Navigation Beacon RA-15 witnessed a purple-tinted EMP cloud emanate from the wreckage of the Covenant Sh'wada-pattern supercarrier Long Night of Solace after the improvised slipspace bomb was activated. The cloud disabled all electronics within its vicinity, including the NAV Beacon.
• During the Battle of Installation 04, Cortana diverted John-117's energy shields into an EMP to disable Halo's phase pulse generators.
• The deep-space artifact let out an enormous electromagnetic pulse that briefly canceled out all communications in the Sol system. It later let out another pulse upon deactivation.
• During the Skirmish over Threshold, John-117 used the EMP emitted by a plasma grenade to disable the electronics of a locked door on Ascendant Justice, which allowed him to open the door.
• The in-atmosphere jumping of the Solemn Penance to slipspace above New Mombasa created a massive electromagnetic pulse that damaged electrical systems in the city, and fried the navigational and safety systems of nearly five dozen SOEIV pods unfortunate enough to drop towards the carrier at that exact moment, plunging them and the Orbital Drop Shock Troopers inside free-falling to near-certain death.
• The UNSC Port Stanley was equipped with an EMP cannon, for disabling ships not hardened against it, which it used against the Hudal-class auxiliary vessel Piety.
• While trying to stop the Didact, Cortana again modified the Master Chief's shields to give off an EMP to disable a carrier wave generator. She referred to it as "taking a page out of our old playbook."
• Niko used an EMP deployed by his drone Michelle to disable an ONI commsat in orbit of Geranos-a before capturing it.
• During the Carrow Conflict, Governor Ellis Gass and her engineers created a makeshift EMP canon using the core of a HAVOK tactical nuclear weapon and an M68 Gauss cannon to use against Jiralhanae Chieftain Hekabe and the vertex, the Forerunner device that allowed him to control the Sharquoi. The EMP temporarily knocked out all of the Forerunner technology in the Sharquoi hive, although it quickly rebooted. This allowed Ellis time to remove the vertex from Hekabe and end his control over the Sharquoi.
• The Guardian Custodes are equipped with a technology similar to an EMP, called attenuation pulse emitters, which can disable every piece of technology on a planet and surrounding space to keep "troublesome worlds" in-line by instantaneously neutralizing local power networks through a series of debilitating pulses. However, with enough time, the damage can be repaired, particularly by Huragoks.
• By October 2559, the UNSC Infinity's Longsword fighters are equipped with Shield Busting ASGM-15 EMP-assisted missiles which use an initial burst of electromagnetic energy to penetrate an energy shield before delivering a hull-penetrating charge.
• During Operation: WOLFE, Fred loses his armor's shields, HUD, weapon sync targeting system and his magmounts to electrolaser EMP bursts.
• On October 14, 2559, during the Battle of Epsilon Clarion, the Spirit of Fire bombarded Epsilon Clarion with EMP MAC rounds which took down the facility's shields, fried all electronics in the area and reduced Epsilon Clarion into a pool of molten lava. The power of the EMP rounds was enough to cause damage to the facility's systems even before the shield came down and to wipe out the code of the powerful Forerunner archeon-class ancilla Intrepid Eye, finally destroying her.

Silver Timeline

• The UNSC used an EMP to disable Condor 325 after John-117 went rogue.
• The Madrigal keystone appeared to release an EMP after John activated it, disabling the power to all electronic devices around the ship while it simultaneously restored power to the Condor despite the earlier EMP knocking it out. The UNSC base quickly restored power by switching to auxiliary generators, but it allowed the Condor the chance to escape.