Magnetic Accelerator Cannon

The Magnetic Accelerator Cannon (MAC), also known as the Mass Accelerator Cannon, is a weapon system employed by the United Nations Space Command on its warships and orbital defense platforms. Essentially large coilguns, MACs serve as the primary armament of UNSC Navy warships and weapon platforms.

Operational design
The theory behind the operation of a Magnetic Accelerator Cannon is the same as that of a coilgun. The system is a linear motor consisting of a series of magnetic coils which accelerate a metal projectile through a barrel up to high velocity. This technology is not to be confused with that of a railgun, in which a projectile is electromagnetically accelerated between two conducting rails.

Firing operation
The firing process uses electromagnetism to fire a metal slug at high velocity. An extremely large amount of current is put through the first solenoid, (coil of conducting wire), which creates a strong magnetic field that attracts the slug. As the slug passes into the solenoid, the solenoid is quickly turned off and the second solenoid, which is closer to the muzzle, turns on, which attracts the now higher-velocity metal slug just like the first solenoid, and the process is carried on.

A shipboard MAC draws power from the ship's reactor and requires a charge of the weapon's magnetic coils in order to be fired. The time it takes to bring the MAC's systems to full charge on a UNSC vessel is the deciding factor during in-combat use. Thus, while a vessel may not run out of ammunition for a long time, (depending on the size/weight of the slugs and the capacity of the ship), a commanding officer has to carefully analyze the situation of a battle and use his shots strategically. The weapon could be fired even when not at full charge, but the velocity of the projectile will be greatly diminished.

Orbital defense platforms have the same firing process, though they launch much more massive projectiles, (3,000 tons), with greater frequency. At the moment a slug leaves an ODP-mounted MAC's muzzle, a pair of thrusters on the bottom side of the station fire for a few of seconds to counteract the acceleration imparted to the station.

Ammunition
Payloads used in the Magnetic Accelerator Cannon weapon delivery system alternates with the platform which the weapon is hosted; warship models tend to use ferric, ferrous, or depleted uranium cores whereas orbital platform models commonly use ferric tungsten rounds.

The standard frigate-based MAC fires a 600-ton slug around 30 kilometers per second. The high muzzle velocity provides the slug the kinetic energy and momentum necessary to damage a target and partially mitigates its unguided nature and its lack of maneuverability. A "Super MAC" mounted on one of the Reach orbital defense platforms was capable of firing a 3,000-ton slug at nearly .04c, or around 12,000 kilometers per second.

Aiming
The size of a Magnetic Accelerator Cannon is such that it is normally an integral component of a warship's structure. Orbital defense platforms are built around the massive weapon. A dedicated targeting computer or an AI is typically required to aim or fire the cannon, as the projectiles are unguided.

Types
There are numerous variations of the MAC technology, determined primarily by the platforms on which they are installed. MAC systems are sometimes roughly divided between "heavy coil" and "light coil" guns. All known frigate classes carry one MAC system, whereas the standard destroyer and the carry two MACs. The Navy's post-war flagship,, is armed with four Magnetic Accelerator Cannons.

Frigates and destroyers
A standard frigate-mounted MAC averages at 183 m. It can fire a 600-ton ferric-tungsten projectile with a depleted uranium core at 30,000 meters per second, and takes several minutes to recharge to full capacity between shots. The large amount of energy needed to fire the weapon is particularly onerous on a warship, and the extended recharge time is a significant factor in combat against Covenant warships. As a result, MAC rounds are often fired at significantly below their maximum potential velocity by an order of magnitude or more. This results in the impacts being much weaker, but the MACs can be fired far faster and such firepower is still sufficient to destroy the shields of most Covenant warships after a few hits. The standard Magnetic Accelerator Cannon is sufficient to destroy any human vessel or severely damage an unshielded Covenant vessel.

The is equipped with the Mark II, Light Coil – 83B6R3/MAC. The is armed with a Mark II Light Magnetic Accelerator Cannon. It is unknown if it is the same model used by the Charon class.

The is armed with the Mark IV, Heavy Coil - 94B1E6/MAC.

The is armed with the 14B11R2 MAC Battery. This battery includes spinal-mounted, twin-linked, 1170mm/647mm high-velocity coilguns.

Specialized and modified versions
The standard MAC can be enhanced with booster capacitors which allow the weapon to be fired three times per charge rather than once per charge. This improved technology was only known to be implemented with the prior to the Fall of Reach. The modified weapon, known as the Mark II, Light Coil - 56A2D4/MAC, charged faster than the standard version, though this is likely due to the Pillar of Autumn 's advanced reactors. Also exclusive to the Pillar of Autumn along with the modified MAC were newer and lighter MAC rounds that had less dense ferrous core, but a harder outer layer of tungsten carbide.

The is armed with the 22B6R3 MAC Battery, which includes three 530cm multi-payload coilguns.

"Super" Magnetic Accelerator Cannon
UNSC orbital defense platforms, s and the mount larger and more powerful versions of the standard Magnetic Accelerator Cannon, nicknamed the "Super" MAC or the "big stick". An orbital defense platform's cannon is 802.2 m long, with the platforms present in orbit of Reach, which were among the most powerful ever built, being capable of firing a 3,000-ton ferric-tungsten rounds at .04c or 4% of the speed of light, impacting with a massive amount of relativistic kinetic energy, which is the rough equivalent to 51.6 gigatons of TNT. Most UNSC and Covenant vessels are destroyed by this weapon, with shielded Covenant destroyers being shattered into "a million fragments" upon impact. . However, these guns, even with assistance from the UNSC Home Fleet, were not powerful enough to pierce the shields of the Ur-Didact's flagship, Mantle's Approach.

By receiving power from ground-based power plants, orbital defense platforms could achieve recharge and reload times as short as five seconds.

The first in her own class, is equipped with four Super MACs, the CR-03, Series-8 Magnetic Accelerator Cannons. In addition to standard MAC rounds, the CR-03S8 is capable of firing various subcaliber rounds, cargo packages, and autonomous kill vehicles with specialized payloads. These nearly 27m-bore coilguns were powerful enough to breach the Mantle's Approach's hull, allowing the Master Chief to enter the ship.

Mini-MAC
A UNSC "Mammoth" terrestrial siegework platform mounts a Mark 2457/35cm HRG; a miniature, mobile version of the standard Magnetic Accelerator Cannon, colloquially referred to as a "Mini-MAC". It is designed to destroy terrestrial and suborbital fortifications and warships.

"Onager"


The Mark 2488 Magnetic Accelerator Cannon, informally known as the Onager, is a relatively small Magnetic Accelerator Cannon used for static defense. A manned version was used to defend the Pillar of Autumn on Reach. The Mark 2448 fires a 15 cm round with up to 1.1 gigajoules (0.25 tons) of kinetic energy. It is 32.6 meters long, making a standard frigate-mounted MAC 5.6 times larger by length and roughly 177 times larger by volume, assuming similar dimensions. After the war, a new automated variant, the Mark 2551, was used by the UNSC Infinity on Requiem. Ivanoff Station was also equipped with several automated Mark 2551 Onagers.

M68 Gauss Cannon
The M68 Gauss Cannon is a weapon mounted on the M12G1 Light Anti-Armor Vehicle as well as on stationary turrets. It utilizes the same coilgun technology used in MAC, but on a smaller scale.

M92 Principle Gauss Cannon
The M92 Principle Gauss Cannon is a weapon system of similar MAC mechanics that runs along the length of the Open Frame 92/Extra-Vehicular Activity.

M99 Stanchion Gauss Rifle
The M99 is a man portable anti-matériel and anti-personnel special application weapon using 5.4mm/.21 caliber rounds. Like the M68 Gauss Cannon, it utilizes the same coilgun technology as a MAC, only on an even smaller scale. Though smaller than conventional ammunition, these rounds are accelerated to speeds fast enough to travel long distances with almost no change in trajectory, punch through any obstructing materials, hit their target, and still retain significant kinetic energy.

Mass drivers
The mass driver is an orbital launch assembly designed to propel low-weight payloads into orbit, otherwise known as orbital lifting, or to deliver them across a planetary system. The operating principle of the mass driver is essentially the same as that of the Magnetic Accelerator Cannon: it is a large coilgun that magnetically accelerates a package consisting of a magnetizable holder containing a payload. While not a purpose-built weapon like the Magnetic Accelerator Cannon, these platforms are still potent weapons of opportunity. While never formally incorporated as a weapon, mass drivers have been used at as defensive magnetic accelerator weapons at Harvest, the Rubble, and Reach.

Halo Wars
"Use the Spirit of Fire's awesome Mass Accelerator Cannon to incinerate enemy troops."

- In-game description.

In Halo Wars, the MAC Blast ability allows the player to use the 's point-defense MACs for pinpoint orbital bombardment. It is mainly used as a support weapon to help the UNSC penetrate heavy Covenant defenses and Covenant bases, and is a potent weapon against Scarabs.

In Skirmish and multiplayer, the MAC Blast can only be used if Captain James Cutter is selected as the player's leader character. In the campaign, the MAC Blast is available in several missions, most notably Dome of Light, during which the player is granted access to forty rapid-fire MAC rounds to destroy a Covenant base.

Halo Wars 2
In Halo Wars 2, the MAC Blast has been upgraded by Ellen Anders and Isabel into MAC Blast EMP', which is very effective against all mechanical units. The EMP MAC is only available during the campaign mission "The Cartographer", where it is used to fire on a swarm of Aggressor Sentinels defending a Forerunner conduit. In Multiplayer and Blitz Mode, its use is limited to Isabel only.

List of appearances

 * Halo: The Fall of Reach
 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: First Strike
 * Halo 2
 * Halo: Ghosts of Onyx
 * Halo: Uprising
 * Halo 3
 * Halo: Contact Harvest
 * Halo: The Cole Protocol
 * Halo Legends
 * Origins
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Dirt
 * The Impossible Life and the Possible Death of Preston J. Cole
 * Halo: Reach
 * Halo: Combat Evolved Anniversary
 * Halo: The Thursday War
 * Halo 4
 * Spartan Ops
 * Halo: Escalation
 * Halo 2: Anniversary
 * Halo: Fleet Battles
 * Halo: The Fall of Reach - The Animated Series
 * Halo 5: Guardians
 * Halo: Shadow of Intent
 * Halo Mythos
 * Halo: Smoke and Shadow
 * Halo Wars 2