Winebars

It's campaign (well, science mode), I would say it's OK in sandbox although I haven't played sandbox very thoroughly. I'm currently unlocking last of the 1500 science nodes. Although MTF isn't very powerful, it's still a very interesting alternative to the particle bed reactor for spaceplanes, eve shuttles, Kerbin SOI orbiters and landers and all that jazz, so MTF is OK. The thing is MCF is just marginally better at power generation than molten salt reactors at this level (and more expensive) AND it's useless as a thermal rocket reactor because of its huge minimal 5m radius, you also get barely any charged particles from it so it's not very useful as a magnetic nozzle reactor as well. So I just can't see any use for it until you unlock advanced fusion so you can burn D-He3, which is a totally different situation. I think it maybe should be able to fill at least some niche to sort of justify its position in the techtree (perhaps let it burn D-He3 from the spot without the tech upgrade?). Now let us compare Solid Core Engine mk.3 + Solid State Generator and Molten Salt mk4. splitting ThF4: Thermal power Mass with generator Core temperature 100% load fuel lifetime Solid core Rocket (1.25 m) 375 MJ 2.51 t 2509 K 177 days Molten ThF4 reactor (1.725 m) 388 MJ 3.47 t 2000 K 2 y 5.13 days So Solid core gives us 149 MJ per tonne, Molten salt 112 MJ per tonne. Solid core doesn't need as much radiator area for the same efficiency as molten salt because of its higher core temperature. You can also get rid of excess wasteheat by running something through the nozzle. Under full load, molten salt reactor does last significantly longer than Solid core rocket (I have yet to figure how many kerbal days does a kerbal year have ) BUT when idle, Solid core lats much longer (ca 484 year vs 33 year). So in conclusion Solid core is better in every situation except for very very long burns, running ISRU refinery for many days. Solid core is cheaper than a molten salt reactor and as a bonus you get a pretty good thermal rocket with an afterburner in the package. Solid core rocket is a better: general utility generator, outer solar system power source, electrical engine power generator, arguably uW network generator because of its price if you don't mind more frequent maintenance. Something similar is the issue of unupgraded Colliding beam. Dusty plasma is just (much) better in every respect, you just can't downscale it, you can even pump fuel around so endurance isn't much of an issue and embrittlement is still fairly low. So unupgraded 3aF reactors only use is if you can't fit (don't have yet) dusty plasma onto your craft because of size and possibly mass if your craft is very lightweight. Although this may be issue of dusty plasma being too good, not 3aF being too bad. It's a good complement to MTF for electric engines. It's only that dusty plasma is better at both thermal rockets and electric engines and both techs cost 2000. The other thing is you get D-T vista with advanced fusion, so people may incline to unlock advanced fusion first

So I played a bit of KSPI science career in recent times. Bugs: Closed cycle gas core engine (lightbulb) generates insane amounts of electrical power (well above its thermal power) when connected to a thermal generator. All warp engines throw exceptions in VAB Tokamak reactor (the original one without generator) doesn't have defaultly set up proper fuel (D-T). I was confused for some time why the reactor doesn't work, then I noticed there is no fuel. Possible/small bugs: The new colliding beam fusion reactor and magnetized target fusion reactor aren't listed in the filter extensions menus Colliding beam fusion reactor doesn't work with the thermal generator IR telescope doesn't need helium for cooling anymore (well I tried it last in 0.25 or so) and its menus are all confusing and don't seem to work properly Nuclear ramjet lacks texture, but that may have something to do with me using Ven's stock revamp. Perceived imbalances I can hardly see any reason to use the new colliding beam reactor over dusty plasma reactor at same tech tier except its slick looks. Dusty plasma reactor generates about twice as much electric power per reactor+radiator mass from charged particles alone. I guess it's because p-B fusion has excrementsty Q so maybe Lithium fusion modes alleviate that problem, but I haven't tested that. Solid core rocket (KSPI NERVA) is better at electrical power generated per mass than molten salt reactor (even thorium) at all tiers. At the 1500 sci tech tier. The only advantage of MCF reactor over magnetized targed fusion at the same tier is that it can run magnetic nozzle. MTF generates more electrical power per reactor mass and has higher core temp for thermal rockets. It gets better next tier with upgraded charged particles generator and/or D-He3 fusion I can't help myself but I feel closed cycle gas core rocket is still pretty damn overpowered: It absolutely outclasses any other engine at its tier in all respects. Even later on I would think twice before replacing it with other engines mostly because the fusion engines don't have all that much higher ISP to justify its use apart from high energy transfers to Jool and such. Lightbulb has silly TWR so you can land with it pretty much anywhere and burns any sort of liquid (or gas you liquify) you stumble upon on basically any celestial body.

I reckon it's been like this for a few versions, so working as intended AFAIK. Current power: The amount of power your generator is creating (in your case it's the energy required to sustain fusion). Max power: The absolute maximum of power your generator can make (you usually don't need to bother with that, the max power in "megajoules display" is more indicative) It's explained in the OP, but some basic info: D-T fusion: Bread and butter fusion mode. High power output. Some charged particles. Fast reactor embrittlement. Breeds tritium just about to sustain itself. D-He3 fusion: "Premium" fusion mode. A bit less powerful but most of the power in charges particles (which is good because you can run magnetic nozzle with them + they convert to electricity more efficiently). He3 is VERY expensive and hard to get. Little reactor embrittlement. Breeds a bit of tritium. T-T fusion: Basically crappier version of D-T fusion, but usable if you for some reason run out of deuterium and don't have access (fuel) to more advanced fusion modes. Also a very good tritium breeder mode. D-D fusion: Not-so-crappy alternative to D-T fusion. Less powerful but generates more charged particles and doesn't embrittle the reactor so fast. Good tritium breeding. p-B fusion: Uses boron which is easy to get with ISRU. Note that deuterium is quite tricky to get outside Kerbin. Not very powerful but okay-ish amount of charged particles + no embrittlement. D-Li6 fusion: Non-embrittling alternative to D-T. Comparable output but little charged particles. Lithium-6 can also be mined pretty much anywhere, albeit much slower than boron. Breeds a bit of tritium. p-Li fusion: Basically a cheaper (and more high-tech) alternative to D-He3: Lots of charged particles, midrange power output (a bit less than D-He3 though), no embrittlement. As for reactor types, basically Magnetised target fusion (OMEGA) is great for compact designs (can be 1.25 m) and thermal rockets (better ISP), power output is actually quite comparable to Tokamaks (the other two), but it can't make use of charged particles, which is a major hindrance in a lot of cases.

People say the Lightbulb is pretty good, I wholeheartedly agree: 8 MN Arcjet, not too shabby. While solid core engine isn't broken, its electric power generation is still pretty damn good. Mk.3 solid core is actually better than unupgraded particle bed fission reactor and magnetised target fusion reactor and hence it makes molten salt reactors kinda useless once you have access to the discrete power generator. Candle is OK, but its power / weight ratio is still very good (about the same or a little better than molten salt)