Plasma weaponry

Plasma weapons are a category of weaponry that utilize superheated plasma to inflict damage. They are the most common form of weaponry used by the Covenant, found in virtually all niches from warships to infantry; most of these weapons are based on ancient Forerunner equivalents. The adoption of plasma weapons in the United Nations Space Command remains limited, though the Human-Covenant War and the subsequent decades have seen the UNSC developing plasma- or particle beam-based weaponry for certain applications.

Covenant
The Covenant's plasma-based weapons are broadly grouped into four categories by the UNSC, based on their functional principles:
 * Bolide-type weapons fire discrete globules of plasma contained in shaped electromagnetic fields; plasma rifles, plasma pistols and starship-borne plasma torpedoes being common examples.
 * Beam-type weapons shape the plasma into a single continuous beam. Examples include ship-borne plasma lances and infantry focus rifles.
 * Projectile-type plasma weapons use a solid munition such as a grenade or missile to contain and deliver a plasma-based explosive payload. The earliest plasma weapons were of this type. Examples include plasma grenades and naval plasma missiles. Plasma projectile weapons are the only type of plasma weapon to have been reverse-engineered by the UNSC as of the Human-Covenant War.
 * Energy blades use electromagnetically-contained plasma to produce incredibly powerful melee weapons. The most well-known example is the energy sword, but many varieties of such weapons exist.

The first plasma weapons used by the Covenant were projectile-based, and enjoyed only niche applications early on. Modern plasma weapons entered Covenant service in various stages largely ushered in by the decoding of Forerunner reliquaries, though incremental improvements were also brought on by independent innovation. The first types were short-range blades and flamethrower-like weapons or projectiles with plasma payloads. The first fully plasma-based ranged weapons to be introduced were the bolide-type ones. These were reverse-engineered from a form of Forerunner multi-tool with myriad functions and firing modes; they could fire single shot, charged shot, rapid fire, or around corners. However, the Covenant could only replicate these functions, imperfectly as they did, in discrete weapon systems, resulting in weapons such as the ubiquitous plasma rifles and plasma pistols. This breakthrough came from the discovery of a Forerunner weapons cache at the Nanakil Reliquary, circa 3rd century CE, and it would come to shape Covenant arms for millennia to come. Bolide-type plasma weapons eventually became almost trivial to mass-manufacture, leading to them becoming the most popular type of weaponry in the entire Covenant. Even so, certain types of ballistic infantry weapons (carbines, needle-based weaponry) continued to have a key role in the Covenant military, even as some weapon types that had once been standard issue faded or became much more fringe.

Another key breakthrough occurred with the discovery and reverse-engineering of plasma beam weaponry, several centuries later. However, with their much more difficult manufacture and certain other drawbacks, plasma beams never overtook bolide-type weapons in mass usage, instead occupying specific niches; for centuries, they were also restricted to starship-borne plasma lances. Most plasma beam weapons fire their beams significantly below relativistic velocities, and are limited to short to medium ranges.

UNSC scientists have noted that despite their different modes of fire, bolide-type and beam-type plasma weapons are fundamentally very similar. Some bolide plasma weapons can be modified with relative ease to fire near-instantaneous and pinpoint accurate beams, eliminating the time it takes the plasma bolide to reach its target. This was demonstrated by Cortana when she reconfigured the plasma projectors on the Ascendant Justice to fire beams instead of torpedoes, and has since been repeated in post-Covenant War experiments. Despite their similarities, however, bolide and beam-type weapons are two entirely distinct technological lineages within the Covenant. It has been suggested that, due to their restrictions on artificial intelligence, the Covenant simply never made the connection due to fixed patterns of thinking in regards to the two categories, or were unable to; on the Ascendant Justice, it took the immense processing power, abstract thinking and pattern-recognition ability of a specialized "smart" AI to do so.

The color of the plasma typically serves as a reliable indicator of its temperature, a reddish or orange hue indicating plasma on the cooler end of the spectrum and blue or white being the hottest. While a common rule of thumb, the color of plasma can also vary to some extent for other reasons, such as the mixture of gases used. However, standard-issue weapons within any particular ministry's armed forces tend to use similar gas mixes for logistical reasons, with more unique colors being restricted to specialist or novelty applications, or weapons used by extraministerial organizations such as fiefdoms. Some plasma weapons are deliberately configured to use lower-energy plasma for power saving reasons or poor battery quality.

Particle beams
High-velocity, long-range plasma beams are generally known as particle beams. However, there is a fine line between the two. Particle beams fire charged particles at significant fractions of the speed of light, making them far more devastating and allowing them to strike at long distances. As the technology is fairly recent, its use is contained to a few select examples. The first are particle beam rifles in infantry-scale applications, though more recently the technology was scaled up to warship size and installed on long-range turrets on a handful of experimental Covenant warships. Particle beams are one of the most precarious entrusted technologies after High Charity's fall; while some anointed fabricaries are able to produce them or the highly specific components required for them, most armories cannot.