All these weapons are only available as starship fittings; they are covered here for comparison, mainly against vehicles. Note that particle accelerators do not operate in atmosphere.
Beam
Laser
Beam lasers fire concentrated light energy in beams against enemy targets.
Fusion gun
Fusion guns use a laser to heat hydrogen to a plasma state, then contain it until a fusion reaction starts, inside a magnetic bottle. When the fusing plasma reaches maximum energy, an aperture is opened in the bottle, releasing the fusing plasma as a high-temperature, high-velocity bolt.
Meson gun
Meson guns make use of the properties of a subatomic particle called the pi neutral meson. Mesons, like neutrinos, do not interact significantly with other particles, and matter is therefore transparent to them. However, mesons decay in a short time into other particles which do interact, and which possess high energy. Mesons are created by the collision of an electron and a positron in the beams of two particle accelerators. In a meson gun, the beam travels to the target, where the mesons decay, causing a large energy release.
Particle
accelerator
Particle accelerators charge and accelerate electrons or hydrogen nuclei to high velocities towards a target. Hits produce both surface damage and radiation effects.
Plasma
gun
Plasma guns use a laser to heat hydrogen to a plasma state, inside a magnetic bottle. When the plasma reaches maximum energy, an aperture is opened in the bottle, releasing the plasma as a high- temperature, high-velocity bolt.
Pulse
Laser
Pulse lasers fire a concentrated light energy in pulses against enemy targets.
Sandcaster
Sandcasters project a granular agent which obstructs light; when they are fired, the agent interferes with incoming laser or energy fire. It can also detonate incoming missiles, depending upon the fuse type.