Hardened plasma

Hardened plasma is a interesting substance. For one, the name is a complete misnomer; it is not plasma, nor does it have anything to do with it. The two states it does take are solid and gas, and the way it changes state is quite different. For plasma stuff, check out Plasma weapons or Fusion power.

History

Hardened plasma is a suprisingly stagnant invention, in a way. From its discovery in the late 2100s, it has not improved or been replaced very meaningfully in all the time since then. It serves its role in its niche very well, and innovation on that has largely been for efficiency and potency, not any groundbreaking new changes.
Originally, hardened plasma was intended as a way to compress hydrogen to a point where it would be more efficient to store as such instead of in water. That did not work out, as the structures formed were very short-lived. Still, it did have another notable quality; sheer durability. Soon enough, it was adapted into what it is today, with a weak magnetic field shaping it while it hardens.

Function

Hardened Plasma Schematic by MadToxin

There are three components to a hardened plasma projection system. There is the projectors themselves, the reaction trigger, and the magnetic controller.
The material used for hardened plasma is essentially a fairly complex powder mixed with some small Nanomachines. When the hardened plasma is activated, be it for a blade or a protective field, the projectors draw in air, and mix it with the powder via a chemical process, which creates a magnetically charged gas.
It then propells it out of the projector, and the electromagnetic field is activated, which guides the magnetic gas into the desired shape, usually a very rough one, and then the trigger activates. It sends a message to the nanomachines to emit an electric charge along with a small amount of a chemical, which starts a chain reaction, rapidly crystallizing and slightly heating up in the process, creating a solid material with incredible durability.
This material is very unstable, however, and doesn't remain crystallized for long. Five or six seconds after forming, it rapidly breaks down and evaporates, depending on specifics like thickness and quality of the powder. This also cools the air down, occasionally resulting in condensation and a light mist near the hardened plasma. Hardened plasma also has a constant mist near it when active, as the blade is still partly breaking down while active.

Uses

There are two main uses for hardened plasma. Protective shielding and compact weaponry. Both are fairly common in their respective use cases.

Shields

Hardened plasma shielding is one of the three main protective measures for military vehicles, from tanks to spaceships. Shielding, armour, and point-defense. Generally, the way this works is different for in-atmosphere and -gravity vehicles. For those, the gas is hardened nearly instantly after being pushed out, since the reaction times tend to be very fast. Complex scanner and radar systems, and often also Predictive Analysis Interfaces scan the area for incoming weapons fire, and the shields are deployed if the attack is dangerous enough. Small arms can't pierce the armour plating, and missiles and such can be intercepted by point-defense. The shield tends to hug the vehicle's form, as gravity does weigh the gas down. Due to wind and other weather factors, the shield is also often inconsistent in thickness and shape, as the gas is pushed around and moved while it hardens.
In space gravity and weather are no concern, and reaction times for shields to deploy are plentiful; a barrage of railgun shots from an opposing ship are likely to come from thousands of kilometers away, and take minutes to arrive. Here, the gas can be allowed to conform to the magnetic fields' shape, and harden uniformly. Shields are also far from a ship's hull, often tens of meters or so, and deployed locally in a small section. Most larger ships also use layers of shields, so that if a shell breaks through all of them, it will still lose momentum and power from each one and likely fail to penetrate the armour proper. The main issue with shields in space is that they require air, which is limited in space. Of course, the amount requires by a shield is miniscule compared to a ship's volume alone, but it is something for a crew to note. In particularily extended battles, some smaller ships can run low on air and need to draw from more important parts of the ship.

Weapons

Hardened plasma-based weapons are relatively few and far between outside the Core Worlds and such regions. Often paired with Layered Chain Blade, a hardened plasma weapon allows one to keep a very compact, yet still highly lethal weapon on hand. Most are fairly small, as the gas takes time to harden, but some specialized systems allow for longer projected blades. Jon's claws, for example, are hardened plasma blades, and can be projected in the blink of an eye, but last barely longer than that as well.
The main style of combat with these weapons is comparatively somewhat difficult. The weilder has to get familiar with repeatedly turning their weapon on and off, only activating it when striking or blocking. This has its ups and downs, as while it takes time to learn and activating a blade takes a moment, it can also be disorientating for one's opponent, as gauging the range is difficult and with an entirely different type of balance of mass, movements can be far more erratic compared to a proper weapon.

Issues

The evident concern with hardened plasma is that it takes time to form. While it's a mere second or two, that time can be vitally important. When railgun rounds fly at supersonic speeds and a blade can reach its target within a second, it's a downside to consider. The other is the issue of fuel. While the powder that allows the crystallization is very efficient, it can still run out. This is usually not a factor in combat, but still exists. Hardened plasma-related stuff tends to also be rather expensive and relegated to more high-tech regions; in the rim-regions, you usually only find it in major clusters.