Codex Energy Tokamak

Tokamak

The Tokamak fuses deuterium and tritium in a ring of plasma held by magnets. It is a tier IV heat source: the heat leaves through Heat Ports to boilers and other plants, or as Hot Coolant to Heat Exchangers. It needs a large energy store to ignite, breeds its own tritium from lithium, and collapses harmlessly when something goes wrong; only a very hot plasma hurts things nearby when it collapses.

How it works

1. Start: the pumps make a vacuum, then the magnets ramp up.
2. Injection: deuterium and tritium flow into the vacuum chamber until the plasma is dense enough.
3. Ignition: once the energy buffer holds the startup energy, the plasma is heated to ignition.
4. Burn: fusion heats the plasma itself (alpha heating) and sends neutrons into the breeding blanket. The blanket makes tritium from lithium; the coolant channels carry its heat into the heat buffer.
5. Heat out: the heat buffer feeds the Heat Ports and the Hot Coolant output.
6. Helium ash is pumped out by the divertors.

Building

Shown size: 11 wide, 5 high, 11 deep (adjustable: Size 11–15, Height 5–16).

One example of many: within the rules on this page, size and arrangement are up to you; the Build Projector shows the plan in every allowed size.

	Key	Block	Count
	A	Tokamak Casing	328
	H	Vacuum Chamber	144
	B	Shielded Sight Glass	26
	F	Breeding Blanket	24
	E	Toroidal Field Coil	24
	C	Coolant Channel	21
	G	Divertor	12
	D	Tokamak Viewport	9
	I	Plasma Injector	6
	M	Poloidal Field Coil (Central Solenoid)	3
	K	Energy Input Hatch (Tier 3)	1
	L	Fluid Input Port	1
	J	Fluid Output Port	1
	O	Plasma Diagnostics	1
	P	Gas Input Port	1
	Q	Gas Output Port	1
	N	Heat Port	1
	0	Tokamak Controller	1

Step by step

Each picture adds one layer, from the bottom up; the newest layer is bright. The controller wall faces you on the left.

Step 1: Layer 1

Parts in this step: Tokamak Casing (A) ×121

Step 2: Layer 2

Parts in this step: Vacuum Chamber (H) ×48, Tokamak Casing (A) ×30, Breeding Blanket (F) ×8, Shielded Sight Glass (B) ×8, Toroidal Field Coil (E) ×8, Coolant Channel (C) ×7, Divertor (G) ×6, Tokamak Viewport (D) ×3, Fluid Output Port (J) ×1, Tokamak Controller (0) ×1, Poloidal Field Coil (Central Solenoid) (M) ×1

Step 3: Layer 3

Parts in this step: Vacuum Chamber (H) ×48, Tokamak Casing (A) ×27, Shielded Sight Glass (B) ×9, Breeding Blanket (F) ×8, Toroidal Field Coil (E) ×8, Coolant Channel (C) ×7, Plasma Injector (I) ×6, Tokamak Viewport (D) ×3, Energy Input Hatch (Tier 3) (K) ×1, Fluid Input Port (L) ×1, Gas Input Port (P) ×1, Gas Output Port (Q) ×1, Poloidal Field Coil (Central Solenoid) (M) ×1

Step 4: Layer 4

Parts in this step: Vacuum Chamber (H) ×48, Tokamak Casing (A) ×30, Shielded Sight Glass (B) ×9, Breeding Blanket (F) ×8, Toroidal Field Coil (E) ×8, Coolant Channel (C) ×7, Divertor (G) ×6, Tokamak Viewport (D) ×3, Heat Port (N) ×1, Poloidal Field Coil (Central Solenoid) (M) ×1

Step 5: Layer 5

Parts in this step: Tokamak Casing (A) ×120, Plasma Diagnostics (O) ×1

Rules

• Footprint: square with odd edge length, at least 11 × 11, at most perf.maxStructureSize (default 16, allowed 5–32); height at least 5.
• Edges and corners: only Tokamak Casing.
• Walls, floor and roof: Tokamak Casing, Shielded Sight Glass, Inspection Hatches, Plasma Diagnostics, the ports and the controller.
• Inside, seen from above, square rings around the centre:
• the centre column holds Poloidal Field Coils (Central Solenoid) from floor to roof;
• the rings in between are Vacuum Chamber: here the plasma burns;
• the outermost interior ring holds the components: Toroidal Field Coils, Plasma Injectors, Divertors, Breeding Blankets, Coolant Channels and Tokamak Viewports (a viewport continues a wall glass to the plasma).
• Needed: at least 8 Toroidal Field Coils, one Plasma Injector, one Divertor, one Coolant Channel and one Plasma Diagnostics in a wall.
• Controller: in a wall face (not on an edge), front facing out, with the inside directly behind it.
• Ports (each works only on its outer face):
• Energy Input Hatch: energy for pumps, magnets, heating and ignition.
• Gas Input Port: deuterium, tritium and helium-3 in.
• Gas Output Port: helium ash and tritium out.
• Item Input Port: Lithium Carbonate for the blanket.
• Fluid Input Port water in, Fluid Output Port Hot Coolant out.
• Heat Port: heat out to a neighbouring plant.

What the parts do

• Toroidal Field Coils hold the plasma. Full confinement needs 8 per interior layer; the example with 3 layers has its 24.
• Poloidal Field Coils belong in the centre; together with the toroidal coils they draw the magnet power.
• Vacuum Chamber: every block holds 10 mB of plasma. A bigger chamber makes more power but also loses more heat.
• Plasma Injectors: each lets in up to 2 mB of fuel per tick and allows 5,000 E per tick of auxiliary heating.
• Divertors take the heat that leaks out of the plasma, up to 4,000 HU per tick each without overload, and pump the helium ash out.
• Breeding Blankets catch the neutrons and breed tritium. Full coverage needs 8 per interior layer; the example has its 24. Its viewports behind the glass front only take the places of channels, injectors and divertors, so coils and blankets stay complete.
• Coolant Channels move up to 3,000 HU per tick each from the blanket into the heat buffer.
• Plasma Diagnostics is required; it watches the plasma.

Startup

Phase	Status line	What happens
Vacuum	Pumping vacuum	The pumps draw 200 E per tick; the vacuum is ready after 200 powered ticks.
Magnets	Ramping magnets	The field ramps up over 200 powered ticks.
Injection	Injecting fuel / waiting for startup energy	Fuel flows in. Ignition starts when the plasma density is at least 0.5 and the buffer holds the startup energy.
Ignition	Ignition	For 100 ticks the startup energy is drawn in equal parts and the plasma is heated to 160 MK.
Heating	Heating	The plasma burns and heats itself further.
Stable burn	Stable burn	From 140 MK.

• Startup energy: volt.fusionStartupEnergy (default 800000000, allowed 1000–100000000000). The energy buffer holds up to 120,000,000,000 E and takes at most 50,000,000 E per tick.
• Magnet power every tick: (toroidal + poloidal coils) × 100 E × field, plus 20 E to hold the vacuum. Without enough energy the field drops; below 80 % a burning plasma collapses.
• If the startup energy runs out during ignition, the plasma collapses.

Important

A strong energy supply The tier 3 hatch of the example (64,000 E/t) carries the magnets and fills the start charge in about ten minutes; a tier 1 hatch would not even carry the magnets. A tier 4 hatch (512,000 E/t) or several hatches start faster. Fill the buffer before you press Start.

The burn in depth

• Fuel: half deuterium, half tritium. When tritium is short, helium-3 takes its place. The injection rate is set in steps of 0.5 mB per tick, at most injectors × 2. The server setting volt.fuelConsumptionMultiplier (default 1.0, allowed 0.01–100.0) changes how much gas the same plasma takes from the tanks.
• Reaction rates grow with the density of both fuels, the plasma temperature and the confinement:
• D-T is strongest at 150 MK and gives 30,000 HU per reaction: 0.2 of it heats the plasma, the rest goes as neutrons into the blanket.
• D-D is much slower, needs a hotter plasma (up to 400 MK) and gives 5,000 HU; it also makes tritium.
• D-He3 is strongest at 2.5 times the D-T temperature and gives 36,000 HU, 0.9 of it into the plasma and nearly no neutrons.
• Losses: the plasma leaks heat to the divertors, more with a bigger chamber and a hotter plasma, less with better confinement. Alpha heating plus auxiliary heating against these losses decides whether the plasma heats up or cools down.
• Confinement = field × coil share × (1 − half the helium share) × (0.6 + 0.4 × stability).
• Stability drops when the density is above 90 % of the field, when the divertors are overloaded, with helium in the plasma, and when the blanket gets hotter than 80 % of its limit. Below 25 % the plasma collapses.
• Auxiliary heating (steps of 1,000 E per tick) heats the plasma directly. With it a pure deuterium plasma can burn D-D and breed the first tritium.
• Helium ash leaves through the divertors into the helium tank. When the helium tank is full, the ash stays in the plasma and dilutes it.

Tritium breeding

• Put Lithium Carbonate into the lithium slot: every item becomes 2,000 units of blanket lithium (at most 200,000).
• Every neutron breeds up to 1.25 tritium (times the blanket coverage); each mB of tritium uses one unit of lithium.
• With full coverage the plasma breeds more tritium than it burns. When the tritium tank is full, the surplus is lost.
• First tritium: start with deuterium only and auxiliary heating, or bring helium-3 from the Rift.

Heat output

• The blanket collects the neutron heat; the coolant channels move it into the heat buffer (500,000 HU, or one second of the channels' heat if that is more). Without enough channels the blanket heats up; above 900 °C the tokamak shuts down safely ("blanket overheated (no heat sink)").
• The divertor heat and the heat of a collapsed plasma go into the heat buffer as well.
• From the buffer the heat leaves through the Heat Ports to the plant next to them, and as Hot Coolant: every mB of water takes 10 HU.
• The switch Heat first to: Ports / Cooling decides who comes first. "Ports" (default) leaves the coolant only what the Heat Ports cannot take this tick. The line "Heat last tick" shows both shares. See Process Heat.
• The water and Hot Coolant tanks hold 32,000 mB, or one second of the channels' heat if that is more.

Collapse and shutdown

• A plasma collapses when it cools below 60 MK (fuel starvation or instability), when its stability falls below 25 %, when the magnet power fails or when the startup energy runs out. The plasma's heat goes into the heat buffer; the gas is lost.
• After 80 ticks the tokamak goes back to injection if the magnets still hold (fuel starvation, instability, startup energy) and re-ignites by itself when Auto (automatic re-ignition) is on. That costs the startup energy again. Otherwise it shuts down.
• Disruption: a collapsing plasma that holds more than 2,000,000 HU of heat hurts living beings nearby (a flash and thunder, no explosion). See Incidents.
• Stop shuts down safely: injection stops, the plasma is cooled and pumped back into the tanks, then the magnets ramp down.
• If the structure breaks, the plasma is dumped and the tokamak switches off.

The screen

• Lines: Status (the phase), Last event (why it last collapsed or stopped) and Automatic re-ignition (on/off).
• Bars: energy / startup energy, deuterium, tritium, helium-3, helium, lithium, plasma temperature, stability.
• Values: plasma temperature, plasma density, confinement, stability, magnetic field, vacuum, fusion rate, fusion power, divertor load, blanket temperature, tritium breeding, heat output, magnet power, net output, fuel injection, auxiliary heating, plasma collapses.
• The switch Heat first to and the line Heat last tick (to the Heat Ports / to the coolant).
• A flow diagram: fuel → plasma → blanket → heat.
• Buttons: Start, Stop, Auto, -/+ for the fuel injection (±0.5 mB/t) and for the auxiliary heating (±1,000 E per tick).

Last event

Text	Meaning
none	Nothing happened yet.
stopped	Stopped with the Stop button.
fuel starvation	The plasma cooled down: too little fuel or heating.
plasma instability	The stability fell too low.
magnet power lost	The magnets lost their energy.
startup energy ran out	The buffer emptied during ignition.
blanket overheated (no heat sink)	The heat did not get out; the tokamak shut down safely.
structure broken	The structure was broken while it ran.

Fuel supply

The Isotope Separator window: 5 energy and tank bars, 6 value, status and redstone lines.

Deuterium comes from the Isotope Separator, a single machine: it takes hydrogen (from the Electrolyzer) and makes one mB of deuterium from every 10 mB of hydrogen, for 400 E, up to 2 times per tick. Hydrogen goes in and deuterium comes out on every side; energy too. Its screen shows hydrogen, deuterium, energy and the deuterium made per tick.

	Glass
			→ Isotope Separator

Tritium is bred in the blanket; helium-3 comes from the Rift.

Automation

• Pipe deuterium (and helium-3) into the Gas Input Port; take helium from the Gas Output Port.
• Lithium Carbonate goes in through the Item Input Port.
• A Sensor Module reads plasma temperature, stability, energy, fusion power, net power, fusion rate, tritium breeding, fuel level, blanket temperature, last event and phase.

Warning

The gas output gives tritium too The Gas Output Port gives helium and tritium from the same tank the plasma burns. A pipe that pulls everything from it empties the tritium. Filter it to helium, or only pull tritium when the tank is nearly full.

Error messages

Message	What to do
The tokamak needs a square footprint with odd edge length (is …)	Build the same odd width and depth: 11, 13, 15.
Wrong block at … (expected: Poloidal Field Coil (Central Solenoid))	The centre column holds poloidal coils from floor to roof.
Wrong block at … (expected: Vacuum Chamber)	Every block between the centre and the outer ring is Vacuum Chamber.
Wrong block at … (expected: …)	In the outer ring only the components listed in the rules; on edges only Tokamak Casing.
Missing parts: …	At least 8 Toroidal Field Coils, one Plasma Injector, one Divertor, one Coolant Channel and Plasma Diagnostics.
Structure too small (…)	At least 11 × 5 × 11.
Structure too large or not closed near …	Close the wall there, or make the plant smaller.
The controller must sit in a wall, front facing out	Put the controller into a wall face, front outwards.
Port not allowed here: …	Only the ports listed in the rules work.

In the world

• While the plasma burns, a glowing plasma ring circles inside the vacuum chamber; the chamber blocks are hidden while the tokamak is formed.
• Startup, ignition and collapse play their own sounds; the magnets hum while they carry current.
• A burning plasma radiates: up to 3 damage per second at its centre with D-T, less with helium-3 (at least 0.25 of it).

Tip

Net power "Net output" is the heat that leaves minus the magnet power and the auxiliary heating. Only when it is clearly positive does the tokamak pay off; a large chamber with full coil and blanket coverage burns best.