40k energy shield qualifications

[Feil]

I'm trying to work on a comprehensive list of the kinds of shields used in 40k, their qualities, and their capabilities. I'm not getting very far, and I suspect many of you know far more about 40k than I do. So, I turn my list to you.


Shields
--Shields can be broken down first into two groups: the Gellar Field and the Void Shield.

Gellar Field
-The Gellar Field is projected by a device mounted on warp-capable craft (universally, or just by the Imperium? If not, what do other races use?) to keep the Immaterium out and the Materium in.
-Utility in Warp Travel: aside from fulfilling its basic purpose, the Gellar Field is also impermeable* to daemons [and souls?]. A daemon outside of the protected ship cannot penetrate the field to get in; a daemon inside cannot get out.
-Utility out of Warp Travel: [can the Gellar Field interdict summonings, impede the motion of manifested daemons, block gateways to the warp, and so on? Or is it entirely useless when out of the Materium?]
*The Gellar Field is subject to ultra-short glitches and malfunctions during which a lucky daemon may successfully penetrate. It may also have finite capability to resist a sufficiently powerful and determined daemon. Ref. Last Chancers book 3, Annihilation Squad, by Gav Thorpe.

Void Shields
-Primarily used on space ships as protection against enemy fire, these also have use on the surface of a planet. Characteristics vary widely and are dealt with below.
-It is impossible to teleport someone through an active void shield.

Imperimeable Void Shields
-Instances of these are usually transluscent, discoloring and distorting light that passes through them. In Necropolis by Dan Abnett, the shield is unable to intersect with the wall, [possibly because of some variety of "ground-effect"?]. Their visibility may be a function of their interaction with atmosphere.
-Conservation of Momentum dictates that these must be as weak as their weakest supporting mechanism. Significantly, they can take sustained bombardment from very heavy ordinance [quantification?], though in Nightbringer a Nova Cannon destroys one [I think, need confirmation, and numbers would be nice.]
-Description of the effect of rainfall on the shield in Necropolis, unless I am imagining things, indicates that incident matter is vaporized on contact. Those underneath do not experience significant temperature rise, however.

Selectively Permiable Shields
-Warships can fire projectiles out. Incoming projectiles are stopped by the shields. Might be caused by a synchronization of shield deactivation with firing, but this is unlikely, because shields take a long time to put up and take down. More likely these shields are slectively permiable, either allowing matter out but not in, or possibly allowing only specified velocities of matter out and in. Like all void shields, these are selectively permeable to light, presumably depending on intensity and going opaque above a certain threshold.
-In some cases (all cases?) objects with low relative velocities can penetrate the shields of a warship. These include fighters and bombers, which can get in under the shields to deliver payloads (indicating that void shields sit far out from the ship hull, unlike the shields in Star Wars, and at a minimum spherical but small like those in Star Trek, but potentially larger and not necessarily round). Other warships can also penetrate shields, but this may simply be a conservation of momentum issue, since a gigantic spaceship crashing into your shield generator will surely pulverize it before the enemy warship can ram the ship itself. Does ramming in BFG cause shields to fall if they are up?

Conversion Fields (should these be grouped as a third kind of shield, seperate from Void Shields?)
-Conversion Fields are man-portable anti-energy fields that transfer energy from an incoming energy weapon or projectile to a storage/release device, reducing the lethality of energy weapons. I need much more information on what these guys do, for instance, can they overload; what happens if they do; do they also slow already slow-moving things; do they dim incident light; etc.

Any help would be very welcome!
-Feil

[Connor MacLeod]

refractor fields, which seem to be some sort of solid barrier defense and designed to scatter/deflect fire without absorbing it. For the most part seem to be very visible, and usually bubble-like.

Note on void shields: Void shields seem to be largely an absorption and retransmission system, akin to the "Heat sink" shield elements in SW shields. They can absorb energy up to a certain limit, whereupon they fail/collapse until the energy is radiated away.

Power fields- various uses and applcations. They can range from structural reinforcement aids (power fields built into shields, as per the '93 Wargear supplement, or into solid defenses/obstacles - like the wall of an Arbites Fortress in the Nightbringer novel.) In some cases they are some sort of "barrier" style defense (behaving more like a wall or armour than an energy absorption/retransmission sytem.) In other cases they behave more like some sort of electricfied fence, where they give a discharge to someone who gets too close.

Null fields- basically a sort of cloaking shield designed to hide/mask a vessel from all forms of detection, including psychic. Exact extent/commonality is unknown, though its mainly seen used by Inquisitorial and AdMech forces.


Displaceer field - rare device. When hit by enemy fire, the device will (if it works) teleport the user away in some random direction/distance out of the path of fire. Miniature warp engine of some kind, IIRC. Does not always work (reliably.)

Perimeter containment fences - mentioned in Imperial Armour 4, its some sort of combination fo electric fence that can vaporize people that touch it, as well as some sort of defensive barrier that reduces severetiy of attacks. The nodes are targetable by enemy fire however, and

Stasis shield - mentioned in various sources, including the aforementioned Imperial ARmour 1. Stasis fields are also used for storage and containment purposes (for such things like perishible cargoes)

[Imperial Overlord]

Conversion field-it transforms part or all of the energy of an attack into photons that are radiated away from protected being. The field is invisible when active, but obviously very active when triggered.

-personal force field defences are only triggered by an attack coming in at high enough velocity, meaning they are much less effective against melee weapons and don't go off everytime the wearer takes a step or opens a door.

[andrewgpaul]

Not sure on how they work these days, but power fields originally functioned in a similar way to void shields, although the field generators simply burned out irreparably when overloaded, unlike Void shields.

Also, they're impermeable from both directions, unlike the other types mentioned (IIRC). They can be designed to 'flicker', so you can shoot out, if you synchronise your weapons with the field.

[Luzifer's right hand]

Conversion Fields can dazzle people with unprotected eyes when active.

Tyranids:
Voltage Fields are created by a biomorph which creates some kind of electric field which dissipates attacks and can damage/destroy electrical devices.
Only 2nd edition afaik so I don't know how canon it is as it.

[Bedlam]

From the Epic system I always though that void and Power fields were essentually the same thing, only void shields (used by the imperium) were designed to shut down before they overloaded and could be reactivated once they cooled down where as power shields (used by orks) didn't have the safety measures in place so just burned out. I doubt an ork would know what to do with an off button anyway.

Refractor, Conversion and displacer fields presumably have some form of scaling problem as they only ever seem to be used on personel rather than vehicles and titans. Presumably power and void shield have the reverse scaling problem as they dont seem to be used on personel only vehicles.

I do remember chaos officers in one of the Gaunts Ghosts novels Honor Guard had reflactor fields which made them appear as "shimmering Orbs" so aparrently they refract normal light as well as other energy and matter. Caffran seemed to think that a tube charge would not breach the shield although it did knock him off his feet presumably by destroying the ground below the shield. Although both Gaunts Power sword and Harks plasma pistol were capable of destroying them. Its also mentioned that the shield was created on a tainted forge world so it seems that this type of shield is not "lost Tech" at least to chaos. The fact that at least 5 individuals in the chaos horde that Gaunt could see at that point had such devices seems to indicate there not that rair to chaos anyway, it might be an example of the Admech keeping all the good stuff for themself as I dont remember many examples of Imerial forces using personal shielding.

[Ford Prefect]

Inquisitors use personal force field devices all the time, and I'm sure that there would be Rogue Traders and other rich private citizens would want to get their hands on stuff like that as well. Also, I'm fairly sure that Priests can get them, given that a Rosarius tends to incorporate a conversion field generator.

They're not exactly common, but the Imperials certainly make use of them when they can.