Class-2 directed energy cannon

The Class-2 Energy Guns, also referred as Twin Plasma Cannons, are the Covenant's vehicle mounted weapon systems, commonly used on the Ghost and Banshee.

Design Details
The class-2 energy weapon is a Directed Energy Weapon that is mounted onto small Covenant craft and is a newer plasma-based projectile weapon system. The weapons power output is 100-250kW. It is powered by a small power source and uses Hydrogen Fluoride as a source of fuel. The design of the weapon doesn't differ much from standard Covenant plasma weapons, using a single collimator covered with a two-piece metal case. The class 2 weapon system is used for heavy combat situations and is employed for both anti-vehicle and ship-to-ship combat, but can be extremely effective in infantry support and suppressive roles. The class 2s role as a anti-vehicle weapon means that the firepower produced by this weapon is considerably high, able to punch through and melt multiple layers of armor until the target vehicles is destroyed, or inoperable. The class 2 energy weapon functions like most plasma based weapons used by the Covenant by rapidly cycling, loading, ignition, and release of plasma at high velocities. The plasma is contained and guided by a electromagnetic bottle which guides the plasma until it either travels too far away from the magnetic source and dissipates, or strikes its intended target.

Against infantry, the lethality of the class-2 energy weapon is severe as injuries inflicted to infantry with light body armor are severe fourth-degree burns, this level of injury completely burns away all flesh, leaving only bone tissue. Body fluids would be subjected to flash vaporization, and fluids trapped in organs or arteries in addition to the rapid expansion of heat would cause ruptures or small steam explosions causing additional damage to the body. Near misses can also cause injury to the target, as they produce severe burns to the area they pass, this can also cause heat trauma or heat stroke from the extreme temperatures of the bolt. Should the plasma impact an object, the impact can cause splash damage creating debris both non-heated and heated that may come into contact with a target, with a crippling or lethal effect. Damage to light armored vehicles is high as the plasma's high kinetic energy and extreme temperatures can punch through it with ease, more heavily armored vehicles can withstand a certain amount of fire before its armor can be penetrated. In the context of the Halo games, all plasma weapons' strength and lethality are compensated for both the sake of ESRB rating and gameplay.

There are several known variants of the Class-2 Energy Gun, but they all work more or less the same way. Ghosts have a pair of cannons mounted on their front, which can raise and lower to hit targets of varying altitude. Banshees have bulkier cannons that recoil with each shot. Covenant exo-atmospheric craft, such as Banshee Interceptors and Phantom Gunboats, are equipped with more powerful weapons known as heavy plasma cannons.

Advantages
The class-2 energy weapon is a medium range weapon, and can inflict very high damage against armor and infantry — the weapon however excels at destroying light armored vehicles and is the primary reason a good number of Covenant vehicles use this weapon system. Vehicles equipped with class 2 weapon systems can halt enemy infantry advance with its ability to deliver harassing suppressive fire; this tactic is also reflected in the Covenant's combat doctrine: destroy enemy morale with harassing fire from distant or hidden snipers and intimate exposure to the alien-ness of their infantry. The weapons small power source coupled with the vehicles design allows prolonged continuous fire without overheating the weapon, excess heat is vented through small vents placed on the vehicle.

Disadvantages
Although the class-2 energy weapon can strike a target at longer ranges, it is not suited for long range combat. The first is the rate of thermal expansion which is determined by the rate of the bloom of the bolt, blooming is the result of plasma breakdown in the air at energy densities of around a megajoule per cubic centimeter. This effect causes the plasma to defocus and disperse energy into the atmosphere. It can be more severe if there is fog, smoke, or dust in the air. As the bolt is accelerated away from the "barrel" of the weapon the plasma begins to decay as a result of the weakening magnetic field. Speed also factors in to this, the faster the bolt is accelerated, the farther the bolt will travel before the temperature of plasma begins to decay and the magnetic field becomes unstable and finally dissipates. As the bolt loses velocity it also loses kinetic damage as it travels longer distances. Each vehicle that uses the class-2 energy gun has their own disadvantages when equipped with this weapon system and as such can either be limited in firing angle or range.

Trivia

 * While boosting in a Ghost or Banshee, you cannot fire the Plasma Cannons because the energy used to fire them is being channeled to the boosters.
 * In Halo: Combat Evolved, the Twin Plasma Cannons fired simultaneously and has the capability of stunning the enemy temporarily, while in Halo 2 and Halo 3, they fire alternatively and lack the stun effect. It should also be noted that the cannons in Halo 2 and Halo 3 are much more accurate during sustained fire.