PPB = Phased Polaron Beam. Widely known for being one of the two Ultimate weapons in SE4 Classic (APB is the other).
The torpedo should be something roughly similar to the SE4 classic torpedo, bullet shaped, with some way of indicating a polaron warhead. Maybe a window (like the plasma missile has), which allows emits a wierd glow.
Rather than Trek, think WW2
I'm not sure whether the polaron glow should be purple, like the beam seen in combat, or yellow, like the PPB component image... I'm leaning towards purple.