Pick air or water cooling and an injection rate, and see the power, steam, plasma and case temperature, how many industrial turbines the steam needs, and the laser shot that lights it. Every number comes from Mekanism's FusionReactorMultiblockData and TurbineMultiblockData.
Drag to rotate. Right-drag, Shift-drag or two-finger drag to pan. Scroll or pinch to zoom.
Build from the bottom up. Step through the layers with ◀ ▶ on the 3D view; it hides everything above the layer you're on. Anything shown as glass can be frame instead.
Width and depth must be odd, from 5 to 17. Height 5 to 18.
The injection rate is how much D-T fuel it burns per tick: half deuterium, half tritium. The controller only takes even numbers up to 98.
Lasers charging the amplifier. A beam stops at the first block it hits, so each laser needs its own side of the amplifier: five per amplifier at most.
Steady state after warm-up, assuming pipes keep up with fuel, water, steam and power.
Put the file in .minecraft/schematics to load it with Create's Schematic Table or Litematica, or in saves/<world>/generated/minecraft/structures to load it with a structure block. A survival Schematicannon may leave the rotors bare; if so, right-click each rotor with two turbine blades.
Laser energy heats the cold plasma by energy ÷ 10 K, and burning starts at 100 million K. The plasma also leaks 0.2% of its lead over the case every tick, so a steady beam levels off far below that. A Laser Amplifier has to release 1 GJ (400M FE) at once.
not burning: T += energy / 100 × 10 burns when: T ≥ 100,000,000 K needed ≈ 10 × (1e8 − 300) J = 1 GJFusionReactorMultiblockData.addTemperatureFromEnergyInput
All the fuel's heat leaves through the case. Water takes a k/(k+c) share as steam, worth 20% back through a turbine; the rest goes to the air, and thermocouples keep only 5% of that.
heat/t = fuelEnergy × injection passive = 0.05 × c/(k+c) × heat steam = 0.2 × k/(k+c) × heat / 10 mB/tFusionReactorMultiblockData.transferHeat
There is no damage counter. Run out of water or back up the steam and that heat goes to the air instead, so the reactor just falls back toward its air-cooled output. The only danger is the core: anything inside the 3×3×3 takes 50,000 damage while it burns.
water short → caseWaterHeat = 0 kill(): entity.hurt(FUSION, 50_000)FusionReactorMultiblockData.tick · kill
Each tick it burns the plasma's lead over 100 million K, capped by the fuel injected. If the plasma it settles at is under 100 million K plus the injection rate, burning stops. With mod defaults the lowest stable rate is 2.
burned = min(T − 1e8, fuel) plasma = case + 5 × heat/tburnFuel · getMinInjectionRate
The pack sets fuelEnergy to 100,000, a hundredth of the default. Even at 98 mB/t the plasma settles around 78 million K, under the 100 million it needs, so the reaction dies soon after ignition.
lowest stable rate: 126 (air), 152 (water) max injection: 98ATM-10-a config/Mekanism/generators.toml
The reactor's water and steam tanks are sized from the injection rate, but only when the rate changes. A reactor starts at 2 and is set back to 2 after every reload, so at 2 they hold nothing and it runs air-cooled. We saw this in-game: water piped in at 2 never entered. Use 4 or more.
maxWater = rate × waterPerInjection // only in setInjectionRate, maxSteam = rate × steamPerInjection // when the rate changesFusionReactorMultiblockData.setInjectionRate · FusionReactorCache.apply
The case holds almost no heat, but the plasma holds 100 J per K, so the reactor warms with a time constant of 100 × (5 + 1/(k+c)) ticks: 75 s air-cooled and 37.5 s water-cooled with defaults, and about three of those to reach 95%.
τ = 100 × (5 + 1/(k + c)) ticksplasmaHeatCapacity 100 · caseHeatCapacity 1