((I've been sick the past few days, and it wasn't pleasant. But I'm getting better now, so I shall mini-roll. Also, @ Happy...
Antimatter is a pretty terrible power source compared to other things that you may have on hand. It's extremely unstable, requires constant power upkeep just to not explode, puts out absurd amounts of ionizing radiation (
which itself requires a lot of mass to shield against), . On the other hand, it can be used to catalyze micro-fusion, so I'll write a quick lore entry to reflect the actual uses of antimatter for those purposes.
It's pretty much reserved for things that don't need to worry about radiation and absolutely must conserve mass. Like long-ranged rockets. Rarely weapons, although it's basically like chucking pure gold at your opponents.))
Antimatter is a form of matter with opposite charge, and a tendency to explode when it comes into contact with the corresponding anti-particle. Not, mind you, with other types of anti-particles. A positron will not react with an antiproton at rates enough to matter. Of course, it's fairly difficult to keep them separated, and so a lot of work goes into containing the blasted stuff.
Antimatter can be used for essentially 1-1 mass-to-heat conversion. The problems include the fact that the reaction products are mostly gamma rays and charged particles with complicated decay cycles. Getting a 100% efficient energy conversion is nearly impossible, and as such an antimatter reactor is generally no more efficient than a fusion reactor. Antimatter is hard to produce, the majority of the supply coming from natural sources such as circumstellar disks and planetary rings. In the case that a large concentration is needed, it can be synthesized in a laboratory at <1% efficiency, which pretty much means it will never be economical without significant innovation. Since it's so hard to synthesize, antimatter harvesting is a valued profession, and sweepers are constantly seeking out dust belts around stars to scour for new antimatter sources.
Saturn was the first commercial center of production, followed by an artificial cloud belt within the vicinity of Jupiter designed to maximize production.
J1407, or Hera, was the first step toward a sustainable long-term source of antimatter. Its brown dwarf companion not only emits some of its own antimatter due to its thin atmosphere and relatively shallow gravity well, but featured a ring system hundreds of times larger than Saturn's, producing several milligrams of antimatter every year. This level of production was enough to kickstart interstellar commerce, so its effect on history is remembered even though the dust ring has since thinned out naturally.
Antimatter, despite its rarity and value, is relatively commonplace as a catalyst for microfission. A tiny pellet of uranium is completely harmless, for the most part, until it gets hit with a couple of antiprotons. A mere pittance of antiparticles can catalyze enough reactions to sail around a star system multiple times using efficient ablative drives, which led to the development of the first torch drive by a human corporation near Hera.
Antimatter is most often stored inside metastable buckyball traps, usually dissolved in a solvent capsule. These capsules are known as AX Cells, which are used by microfusion reactors to produce a steady reaction when supplied with deuterium or helium-3. Despite the name, ground-based microfusion reactors are necessarily heavy, requiring layers of shielding to protect against the gamma rays. They can weigh several tons, and are difficult to fit onto a portable unit. In space, however, microfusion cells can be tiny and are a preferred choice for low-mass operations and missile systems.
Fire at the jetski and take cover. Preferably in reverse order.
[3] You take cover... behind the hydrogen tank! The thing is well-armored, and the assailant surely won't fire at you, risking such a big explosion! That could kill him as well as everyone nearby. Despite the threat, however, you still hear firing. The target is firing at the others on the dock, who follow behind you! The shooting soon stops.
[5] vs (5): Hitting a moving target at distance is difficult. The jetski swerves side-to-side, and you even see a shot impact the target, knocking up some black dust but ultimately doing nothing to stop the jetski.
The target arrives at the dock, and despite having a large black wound on his side, leaps out and starts running up the pier to get a shot past the hydrogen tank.
"I guess this is what people call ragdoll physics."
Eh, can't risk it, I'll just insta-kill him.
Shoot him with the rifle.
Initiative[6] Vax
[4] Guy
[1+2] vs (6): Your bullets lose so much speed travelling through water droplets that they do, well, nothing.
(5) vs [2+2]: On the other hand, the guy's laser still manages to deal some damage to you when he counterfires, popping ANOTHER COOLANT PIPE IN YOUR SUIT.