The Interceptor grid and the E-Web are two mainstays of the Earth alliance defense technology since their inception, in the early 2150's, and are still today a classified technology. Their diffusion is strictly controlled, and, while after the constitution of the ISA the interceptor technology has been made available, upon request, to other Isa members, the E-Web is still an Earth Alliance proprietary technology. In this essay are presented in an organic form the basic working principles of both Interceptors and E-Web, but the detail internal technologies that allow the effectiveness of these systems, particularly the ones of the E-Web, cannot be diffused beyond a certain degree, so we apologize in advance for the unavoidable partial censorship.

In the first stages of his development, Earthforce directed his efforts assuming as correct the statement that the space fightings will imply engagement at ranges of tenth or hundreds thousands kilometers, but a small time frame and some experiences and information gathering allowed to discover that, usually, given the tactical implications of the Hyperspace jumps and of the ambush tactics, the ship - to ship engagements generally took place at very closer distances, from 15-20000 Kilometers to a few tenths kilometers. The meaning of this is that the best weapons known at the time (2150 or so) for these fighting distances were the particle beams and the plasma cannons or similar. (and eventually the railguns, but the Earth Alliance is the only known user of these effective short range weapons).

The problem was how to defend against plasma bolts and particle beams and the response were two: the Aegis multi layered armor, whose effectiveness, both in the original form and in the "Carbonat" evolution, is well known and proven, and an active defense system, that was exactly the Interceptor/E-Web barrier.

First of all, must be made clear a fact: the interceptors are made of two projective elements: one of them, the "Bolt Interceptor" works against plasma and ion bolt weapons, operats with bolt weapons as active subcomponent, and, theoretically, each plasma/ion bolt weapon can operate as interceptor in this mode, that essentially is an high rate of fire plasma/pulse weapon, with a targeting system that enables the weapon to hit the incoming plasma bolt.
The plasma bolts are maintained in their shape and density thanks to the particular conformation and internal dynamics of the bolt itself, that is structured to generate a self containment magnetic field. From the physical point of view, it is a plasma structure able to generate his own magnetic containment bottle.

The self containment field decays progressively, and this is the reason of the limited range of the plasma/ion bolt weapons respect to the beam weapons: on the other side, a plasma bolt, given the same power feeding requirements of a weapon, ensures a greater terminal effect, both in terms of penetration and explosive terminal damages. This is the main reason that pushed to merge in the OMEGA cannons and in similar systems both the pulse and beam capabilities and in other systems the laser/bolt capabilities; a plasma bolt is relatively slow respect to a particle beam (this last operates with relativistic speeds)or a laser (light speed), but has mass and energy capable to deliver both thermal/blast effects and concussive/momentum related effects, with heavy damages.

Overall, the concept of the interceptor is simple: an incoming plasma bolt is perfectly traceable with a radar, and his trajectory can be extrapolated with high precision. Another plasma bolts that hits the enemy projectile destabilizes his self containment field, and so the bolt explodes leaving the attacked unit unharmed.
The difficulties emerged from the fact that, to obtain the direct hit against the center of an object that travels at 10000 or 20000 meters/seconds and presents an useful target of a few meters, are required an awesome accuracy in a series of subsystems: for example, the tracking radars must obtain the position and the speed of an incoming bolt with an error of less than respectively 1/300000 for the position and 1/500000 for the speed, the angular overall error of the interceptor (so the sum of the angle errors of the tracker and of the weapon) must not exceed 1/150000, and the speed error of the interceptor bolt must not exceed 1/2000000.

The technology of the "bolt" interceptor is just this: an extreme accuracy and speed of the tracking systems, of the weapon turret movimentation engines, of the closed loop bolt speed control systems of the interceptor bolter, and an exasperated accuracy of the bolter itself.
Must be remarked that the development of the first interceptors required three years, but was possible in such a small time frame because large part of the subcomponents and subsystems (mostly the tracking radars and computers and the high precision, high torque electric engines required for the aiming of the turrets) were yet available, mainly because were developed years before for an experimental anti-railgun laser defense system developed by the DARPA in the early 2100's.

The other  active element of the interceptor is a "Focal Field Projector", a powerful and narrow beam electromagnetic field emitter, that, aimed against an incoming particle beam, is capable to disrupt it, with the same effects (but in a higher scale) of the E-Web.
The Focal field Projector in its original incarnation was extremely effective against the charged and neutralized particle beam weapons commonly used among the Youger races, and, while requiring the same accuracy of the bolt interceptors, with the further complexity that is related to the relative obliquity between incomping beam and focal field beam, was an extremely effective component of the Earth Alliance's defnsive grid. 

These subsystems, and the whole system engineering, has never been developed at the level of refinement of the Earth alliance by other alien powers: the Narns has always followed the weapon engineering guidelines of the Centauri, the Centauri put their bets on the gravitic shields, the long range weapons and the electronic warfare, the Minbari, after some work in the field of the interceptor technology, put the whole research and development activity out of their area of interest for a series of reasons, essentially because their superior technology and ranged firepower and the Stealth system allowed them to win a fight well before the possibility to be hit by plasma weapons*, while the Shadow beams, the other potential menace, seemed uninterceptable**.
So, actually, the Earth Alliance is the only master of the Interceptors, that, given the actual potential menaces, are back in the limelight.

*Must be remarked the fact that the interceptors could have had a material effectiveness against the Minbari Anti Neutron beams, but the tracking system of the Interceptor Mk1 was exclusively radar based, and so had strong difficults in tracking a neutral particle (anti neutrons/neutralized antimatter) beam, and jammed by the powerful ECM of the Minbari.
The interceptors Mk2 (Omega and others) and Mk3 (Warlock and others) are unjammables and able to track a wider range of different types of incoming fire.  A further remark is that the Minbari ships lacks a close-in interceptor capability against the plasma bolts, and so, in the few occasions in which our most effective warships ( Nova ) survived until a very short range, until to acquire the Minbari units with the manual emergency weapon controls, the plasma cannons of the Novas were able to inflict devastating damages to their warships.
The short range firepower of the Novas was considered impressive even by an advanced and powerful race as the Minbari, that, particularly in the last period of the war suffered not negligible casualties in forced short range fightings (see Flynn colony battle). After centuries of all-beam armed warships, the Minbari resolved to design the Whitestars with neutron pulse and fusion pulse cannons, besides the main Neutron Beam cannon.

**A shadow beam, as all the Bosers, can indeed be intercepted and partially dissipated by the Focal Field Projectors of the EA interceptor Grid, as happened with the bosers used by the Drakhs in their war against us. The plasma projectiles of the Shadow fighters and Scout ships are interceptables, and were intercepted by the Mk2 systems of the Hyperion-N's and of the Nova-N's of the EFNI in the fighting that ensued between EFNI units and a Shadow patrol in the "Bright Eagle" mission of October 2259, and that allowed to gather relics and pieces of equipments from the destroyed shadow units.
This is the only known real fight between Earthforce ships and Shadow ships, even if encounters between shadow units and EA fighters or ships have been documented, and some missing explorative units of the EA have been probably captured or destroyed by the Shadows, while fighters of the Babylon 5 garrison squadrons fought bravely against the Shadows in the Shadow War (2259 - 2261).

Historical note - Effectiveness of Plasma Bolt Weapons This note is intended to present the effectiveness of the plasma bolt weapons even against a technologically advanced enemy, but lacking interceptor capabilities. All the plasma bolt weapons are less ranged respect to the beam weapons, both particle beams and lasers, (even if the Ion weapons reduce this range gap), but their effect on the target, in terms of penetrating power and, mostly, ablative/explosive effect, is impressive. The interceptor technology is a strong addiction to the survivability of a ship, particularly if in conjunction with an effective armor. Fig.1 - Plasma pulse fire against a target. Fig.1 - Plasma pulse fire against a target - II Fig.3 Fig.4 - Damages of plasma bolts on the Shargoti cruiser. Fig.5 Fig.6 An engagement sequence of the Battle of Flinn colony (2247-Earth Minbari War) - A Shargoti war cruiser was attacked by the E.A.S.Patton, E.A.S.Sunstorm, and E.A.S.Lancelot. The Lancelot was destroyed by the Minbari unit, but the Sunstorm was able to close the distance and fire some salvos against the Shargoti (fig 1, 2), heavily damaging it (see the craters of the plasma bolts on the hull, and the destroyed root of the upper fin in fig.4). An hit of the Minbari warship destroyed two reactors and three engines of the Sunstorm, and damaged the weapon energy grid (fig.3), so she was put out of combat, and was barely able to jump away before being destroyed. The Patton, with the plasma cannons inoperative due to the damages yet suffered, rammed and destroyed the Shargoti (figs. 5-6). The E.A.S.Sunstorm came back to the solar system after a nine weeks travel through the hyperspace, without communications, with the navigation ensured by the sensors of a shuttle and with only one engine operating at 7% of the nominal power. She emerged from the hyperspace two days after the Battle of the Line and the end of the War.

In this paragraph are provided only the general working principles of the E-Web. The technical details and data are still classified, as classified are the details of the Focal Field Projectors integrated in the interceptors.

The E-Web was born as a defensive electromagnetic shield against the particle beams, and quickly evolved in a two-stage system, effective against both charged particles and neutralized particles beams, (except pure neutron or anti neutron beams) and with an additional effect against plasma bolts.

Essentially, the E-Web is a grid of clusters of field projectors, that are commonly known as "anchors" or "pits", placed in a regular pattern. The field generated by these projectors can be represented as a regular mosaic, as can be seen in fig.7 (in fact, the E-Web is invisible). The whole systems is fed by an high frequency, high voltage current, and, given the nature and the position of the projectors, are generated synchronous electromagnetic fields. The combination of perpendicular fields has a dissipative effect on a particle beam, whose inner core (see fig 8) is spread on a larger area.
The overall energy released on the target is about the same of the undisturbed beam, but it is released on an area that varies between about three and seven times the original impact area; the piercing power of the beam so is proportionally reduced.

It is clear that the E-Web reduces, but does not eliminate the terminal effect of the beam, and a passive material armor is needed to avoid the hull penetration.
The E-Web alone is unable to avoid the effects of an hit, but the combination of E-Web and multi layered armor allows an overall high resistance against the incoming beam weapons fire. Must be added the fact that the E-Web, while extremely effective against charged particle beams and neutralized particle beams, it is ineffective against neutral particle beams, so, the Antimatter/antineutron beams used by the Minbari ships were partially immune to the dissipative effect of the E-Web Mk-1, while the more common neutralized particle beams or heavy particles beams, used in different forms by Dilgars, EA, Centauri, Narns, LONAW, are subject to the dissipative effect of the E-Web, as the Boser Beams.

Fig.7 - General structure of the E-Web - in the picture the E-Web field is colored (blue) to show his shape, while, in fact, it is invisible.	Fig.8 - Dissipative effect of the E-Web against a particle beam.

A further step in the E-Web technology, introduced in 2185, was the integration of the capacitive layer (E-Web second stage) in the Earthforce armors: the EA armors have a multi layered structure (see Armors), and , to work properly, they need some void spaces between some particular layers. The addiction of two thin conductive plates on the internal faces of the void layers, and the charging of these plates with an high difference of electrostatic potential (billions of Volts) transformed the system in a powerful capacitor.

Effects of the second stage of the E-Web against a Plasma Bolt.

fig.9 - The plasma bolt penetrates the external layers of the armor.	fig.10 - The plasma bolt is disrupted.	fig.11 - The plasma bolt is spread on a larger area of armor, with reduced penetration.

A plasma bolt (that is intrinsically conductive), when it comes in contact with both the charged plates (after a partial penetration of the armor, fig.9) short circuits the capacitor,(fig. 10) and a powerful current, an electric discharge, travels through the plasma bolt, disrupting his structure and spreading it on a larger surface of the inner layers of the armor (fig 11). Even in this case the armor is ablated and partially destroyed, but the structural integrity of the hull and of the internal systems is protected, and the ship is still able to fight, being subject only to the phisycal (momentum) impact of the plasma/ion bolt. This, obviously, until a certain level of power, after which the armor is pierced. Anyway, the addiction of the second (capacitive) stage to the E-Web near doubles the overall resistance of the armor against the Plasma/ion weapons.

The combination of interceptors and E-Web, used on our warships from the beginning of our presence in the interstellar arena, was one of the most important factors in the overall effectiveness of our ships: even against more advanced races, like the Centauri, some worlds of the LONAW, the Narns (They were more advanced than the EA until the reconstruction after the Earth-Minbari war), and the Dilgars, our Navy was always able to easily survive fire barrages that would have left just molten slag of the vast majority of the capital ships of other races, allowing to reply to the enemy fire with deadly effectiveness.

The relative ineffectiveness of the Interceptor Mk1 and of the E-Web Mk1 and the unlucky behavior of our armors against the Minbari weapons was one of the most relevant factors, besides the blinding of our sensors because of the Minbari Stealth equipment and Electronic Warfare systems, of the terrible losses suffered and of our hard defeat in that war.

Actually, the evolution in both the passive (Carbonat Armors, Nanotechnologycal Armors) and active (interceptors Mk2 and later, E-Web Mk2 and Mk3, Ion bolt interceptors) defenses has enormously improved the situation.

At the date, the Earth alliance ships are by far the hardest and most survivable crafts of the younger races, and among the better armed, and this combination has proved again to be extremely effective during the Drakh War, compensating with a large gain the relatively low speed and lack of maneuverability of our units. Against the Drakhs we had a loss rate of 1 to 1.8 in our favor during the Earth battle of 2266 an 1 to 4.2 in the "Sudden Nemesis" battles of 2270.

The interceptor technology, as remarked, is extremely effective against bolt weapons: the mainstay of the Thirdspace Aliens weapon systems is an antimatter bolter of inusitate power (see Thirdspace Warship technical essay), but even this weapon can be intercepted; the interaction between the antimatter bolt and the interceptor plasma bolt is extremely effective, and ensure the dissipation of the incoming bolt.

The acknowledgment of this fact was at the origin of the strategical sacrifice of the Earth Alliance, that allowed access to the interceptor technology to the members of the ISA, namely the Narns, the Centauri and the Minbari. Both the Centauri and the Narns integrated some parts of the technology in their weapon systems, the Minbari were yet developing their own proprietary technology, and, BTW, refused to allow to the EA the access to some heavily needed Minbari/Vorlon technologies like Vorlon Bio Armor, Vorlon Shield, and neutron beam weapons. This is a behavior that can be explained, but must be remarked that the Thirdspace Aliens are a clear and present danger, that a war against them will be won or lost by all the members of the ISA united, and the price of a defeat will not be an unfavorable peace treaty with heavy conditions, but the total extinction of our peoples.

Maybe that the concept of racial extinction could seem something abstract to the Minbari, but the Human race have been on the verge of the extinction two times in less than thirty years, and this is a legacy that leaves an definitive brand in the memory of a people.