Coming back to this topic, I have been thinking on how to visualize these weapons.
For the Sub-Capital PPC, I think that peak power demand is the biggest technical problem.
More then a DropShip's powerplant can normally deliver, so I had to find an in-universe technical excuse for reduce this peak.
Currently I am thinking of having circular PPCs that slowly build up the particle load over more time to vastly reduce the peak power demand, and with some extra parts to cause the particles to exit at a specific angle, see picture: https://i.imgur.com/x4Qjmsh.png
Check out
circular particle accelerators. Essentially you have a 'gate' in part if the accelerator that is designed to keep the particles traveling in a circle, but that gate can also be deactivated to let the particles out in a stream. You rotate the circular accelerator so the exit gate is pointed where you want, and just turn that little part off to let the particle stream go in that direction.
As for power demands, that may work, but you would still have the need to keep all the particles contained in the accelerator anyway, and the more particles you have inside the more energy you would still need to keep bending their path. So you may still need the overall power demand, but you are right about it being a steadier build up. However, damage to the accelerator will not only damage the emitter, but that particle stream will escape, potentially into your ship.
The fun part is when you make one of these large enough to be the circumference of the ship. So you have a 'spinal mount' particle beam weapon, but it/they can only be mounted in the LBS/RBS arcs (changing the course of the beams is really difficult), you would have to spend one thrust point to reflect aiming the ship's waist at a target, and they can only be aimed at up to 2 targets (three points define a plane, the firing ship is one point, the emission cone of the particle emitter effectively defines a plane).
You would also have to make a rule about the size is proportional to the width of the ship, since it would be installed just under the armor, but also have the gate openings as close to the surface as possible to avoid having a 'girdle' on the 'waist' on your ship (also add Docking Collar penalties by reducing the max limit?). Since a ship 8* the mass is only 2* the L/W/H of a smaller ship, that means if a 100 kton Warship has a SpNPPC that can do a max of 400 standard damage, then an 800 kton Warship mounting a SpNPPC would be able to do 800 standard damage. Since SpNPPC requires the ship to maneuver to aim, all penalties for firing at smaller targets are doubled.
Now this gives me a 'flak' idea for NPPC weaponry. If you fire the particle stream for a longer period of time, and use the magnetic aiming system to rapidly scatter the beam, you might be able to get an anti-small craft capability out of it. It would have the NPPC's range, but the damage would be lower, and it might still have a penalty. Similar to how CIWS uses a single stream of bullets but sprays them in the path of a missile.