Particle Beam Weapons
Like Laser Weapons, particle beams are a popular concept in science fiction. Streams of charged or neutralized particles are accelerated to awesome velocities and projected at a remote target. Like a hail of trillions of atom-sized (or smaller) bullets, the particle beam smashes into the target, releasing thermal energy and creating radiation. The unlucky target is irradiated, cored through, or exploded into chunks!
Particle beams combine some properties of larger-projectile kinetic energy weapons and the laser directed energy weapon. Particle beams can travel at high-relativistic velocities close to the speed of light, able to reach targets nearly nearly nearly as quickly as a beam of photons. But their working medium are particles with mass, which gives them different propagation and interaction behavior. Often high-energy particles can penetrate into a target or release showers of secondary radiation that penetrate deeply. This irradiation also offers a soft, insidious means to make technology fail and kill biological beings (or anything dependent on nanometer structures and molecular systems) without having to physically melt or blow apart the target. Yet a particle beam's mass flow is generally so tiny that they are not limited by physical ammunition but the power required to drive this little mass up to high speeds and thus energy.
Depending on configuration, particle beams can be highly utilitarian systems with a wide range of not just weapon but also sensing and propulsion applications. They can deal significant radiation damage at low power or focus, or transfer enough energy for explosive vaporization at high energies. Their accuracy is exceptional and their range can be significant, providing direct-fire engagment capability out to the limits of the weapon mounts and supporting sensors.
Defending against particle beams is possible with appropiate material composition and in some cases, magnetic fields.
The limitation of bloom
There is one fundamental problem with weaponizing particle beams. To accelerate a particle beam efficiently, we want to use electromagnetic fields - gravity is way too weak and dissipates very quickly to accelerate particle beams without completely absurd assumptions (consider: the entire mass of the Earth amounts to 1G of acceleration. The forces in a particle accelerator can be in the hundreds of millions of Gs), and neither the weak nor the strong nuclear force reach sufficiently far. Electromagnetic fields are wonderful! To accelerate particles with an electromagnetic field, they must be charged positively or negatively. But a cloud of positively or negatively charged particles will experience charge repulsion, giving rise to electrostatic bloom - the tightly bunched-together group will disperse into a weak, wide-area cloud. Too unfocused, the fearsome particle beam will not do much damage. Maybe it will irradiate the target, but the beam may disperse so widely that it becomes indistinguishable from the cosmic background radiation you find everywhere in deep space.