I'm all for many prototype rolls, but I feel like spending our space gas for more top speed is less useful federation wide than sending it to the fuel tanks for range.
If we were specifically building for interceptors or something I would make the other choice.
Considering where we are in the timeline it sounds like we'd jump to the TOS-Movie-Era Nacelle Designs early, as TOS-Show-Era nacelles still have the spinny impellers.
Hmm, this is a tricky one. Sayle, do we have any idea how often the upgraded ramscoop is going to work? Like, does the advantage apply for 50% of all typical warp travel? Upon re-reading I'm assuming it mostly applies in stellar systems where the space matter is at its densest? And how much of an advantage? 0.1 of a warp factor? 0.2?
If it's ~0.2 of a warp factor in or around a star system this could actually be pretty powerful; system defense ships could move and respond faster, especially if they're all sporting warp 5+ engines. If your enemies are expecting a sprint of warp 7, having a sprint of warp 7.2 could mean the difference between loss and defeat.
Also, are we forced to use this new technology on the next generation of nacelles? If it's too weak or expensive, can we just use standard hardware?
The new injectors slowly take shape. First is the shell over the collector, made of a permeable material that atomic particles are able to pass through with an extra pull from the electromagnetic fields emitted by the new collector. Then comes the particle filter, which diverts any heavy elements away from the central collection point and channels them out the exhaust vents at the edges and away from the nacelles entirely. Here the incoming hydrogen is diverted into a collection of spherical tanks as needed to control the total energy entering the warp plasma, which can then be stored as extra fuel or pushed back up to the particle filter for disposal when at impulse speeds. Last is the particle accelerators, which use waste energy leaked from the warp plasma at high injector throughputs to recycle the energy into the incoming hydrogen for an extra punch at high warp factors.
On paper it certainly seems an elegant system, but there are multiple assemblies and control systems at work that will need real-world testing to confirm their effectiveness. Next up is the injector and control system for the main warp plasma, which presents a dilemma. The standard system used so far for United Earth and most member species is the plasma vent, which provides exhaust channels and hatches for energetic plasma to escape the system. This allows the engines to run with powered warp plasma at sub-warp energies in the nacelles at all times, as any unexpected external energy inputs can be instantly and harmlessly mitigated by regulating the overall plasma energies with venting from the nacelles.
The alternative being suggested is instead a ring of confinement coils just below the skin of the nacelle and enveloping the smaller warp coils. This would compress the warp plasma down and enable higher temperatures - and therefore higher performance from the nacelles themselves, which would be subjected to a denser particle field on the internal surface of the warp coil. The remainder of the coil would be protected in a low-density regime that would preserve long-term performance.
The disadvantage of this is that even with the warp plasma further from the external surfaces of the nacelle that the loss of energy-shock protection will prohibit a continual presence of energised warp plasma in the nacelles for safety reasons. With the existing plasma kept 'cold' risks should be minimal, but realistically speaking it means that a charge time of ten to twelve seconds will be needed to make the transition to warp speeds. It also means that any energy surges at warp speeds will induce uncontrolled speed variations or cause system failures. But in exchange for these unlikely but possible downsides, the ship's efficient cruise speeds could be enhanced by up to half a warp factor.