"Ion Cannon" is the general term used to describe a class of weapons widely used throughout the galaxy for the purposes of disabling and capturing targets without causing significant physical damage. Through the years, the basic concept behind ion cannons has spanned many applications, ranging from Kuat Drive Yards V-150 Planet Defender ion cannons, capable of disabling most interstellar capital ships with one or two shots, to the comparatively tiny SW-4 turret ion cannons mounted atop the typical Y-Wing.

All ion cannons operate by firing highly energetic bolts of charged particles along a pre-determined trajectory toward a target. Most ion cannons operate by pushing hydrogen ions through electromagnetic particle accelerators and projecting them out into space. Other common elemental ion fuels are ionized oxygen, carbon, or nitrogen, each producing different colored blasts depending on the specific spectroscopy and purity of the ions used. Some cannons use polyatomic ions such as Ammonium, Hydronium, Hydrogen Sulfate, Nitrate, or Perchlorate. Although cheaper to use since polyatomic substances are easier to obtain than elemental ones, they generally are not as effective at disabling a target's circuitry and electronic systems.

Despite preconceptions, it is not the actual ions fired by ion cannons that disrupt and disable electronics. When charged particles change speed or direction, they emit energy in the form of electromagnetic radiation. When the packet of charged particles from an ion cannon contacts the hull of a ship, it makes a radical change in speed and direction as the velocity of its particles slow to near zero relative to the target object. This sudden change results in a strong electromagnetic pulse that knocks out and disables all electronic systems within a specific radius depending on the intensity of the ion blast. Physical damage associated with ion cannon attacks is generally quite light. However, should critical power control systems suffer a sudden surge or disruption, secondary explosions become a distinct possibility.

Imperial star destroyers often use gunnery control stations to concentrate fire from several ion emplacements against a single target to try and disable a vessel with its opening volley, allowing assault crews to target and secure the vessel. Ion cannons are also popular among privateer and pirate fleets for the same reason. The cannons allow raiders to capture ships and keep their cargo intact. Several modern Imperial fighter designs also sport ion cannons for additional flexibility in mission assignments. Ion cannons are potent starfighter weapons. In the early days of the terrorist campaign of the Rebel Alliance against the Galactic Empire, rebel Y-Wings and B-Wings were often equipped with ion cannons to disable Imperial freighters and capture their cargoes intact. As a result, the Alliance was able to steal the Empire's equipment, and the captured ships would serve in the insurrectionist forces as well. Fighter attacks using ion cannons allowed the Alliance to capture combat starships, such as Nebulon-B Frigates and Corellian Corvettes which made up the backbone of the Rebel fleet before the addition of Mon Calamari Cruisers. Prior to contact with the Alpha Quadrant and the United Federation of Planets, ray and particle shielding were often separate considerations during battle. A commander not expecting his enemy to have access to ion cannons or missiles might power down his particle shields in order to conserve more of his capacitors for ray shielding. Unfortunately, ray shielding does not effectively impede ion cannons, because they do not employ an "electromagnetic jacket," as turbolasers do, to keep the particle bolt from dissipating over large distances. Although this means that ion cannons have a comparatively limited range vs. turbolasers, they can cut through ray shields with little problem, and this fact was taken advantage of at the Battle of Hoth (below). However, since contact with the Federation at Imatia, where shields proved ineffective against exotic StarFleet weaponry, shielding configuration standards have undergone sweeping changes, and it is now standard practice to integrate ray and particle shielding levels onboard warships, making the "ion window" problem no longer a pressing issue.

Typical Imperial ion cannons are operated in a similar fashion to turbolaser emplacements, and are equipped with gunnery crew stations, independent tracking and targeting computers, a cooling grid and a turbine generator. However, because these emplacements are basically particle accelerators processing large amounts of ion fuel, their destruction can have a widespread negative effect on surrounding ship's systems, as any disruption of the electromagnetic fields will most likely cause a pulse effect and disable nearby electronics.

StarFleet engineers were initially troubled by reports of the abilities of heavy ion cannon fire to cause wide system disruption effects similar to that of a small ion storm. Although Federation starships are largely not as vulnerable as Imperial cruisers to ion cannons because of their plasma-based power transfer networks, they not entirely immune to their effects, and a concentrated enough volley of ion cannon firepower will cripple a StarFleet vessel just the same.