A particle-beam uses a high-energy beam of atomic or subatomic particles to damage the target by disrupting its atomic and/or molecular structure. A particle-beam weapon is a type of directed-energy weapon, which directs energy in a particular and focused direction using particles with minuscule mass. I think this could be kind of a mix of the railgun and Ion laser, firing a single, long-range shot of energy.
Particle Beam
I think that would be too similar to the ion and railgun to create a whole new non-rotating weapon. Maybe a module like the prism that you can fire the ion into. Something like a capacitor, Ion fires into it until it's fully charged, then it discharges the shot in a extremely short duration beam. It would probably have to be incompatible with the prism redirection and multiplication effects though, as that would make it too easy to create a one-shot-one-kill weapon