Fusion Reactor (Mekanism)

The Fusion Reactor is a late-game multiblock structure added by Mekanism. It consumes Deuterium and Tritium to generate large amounts of power.
== Construction ==
The exact list of materials varies depending on how many Reactor Glass blocks and Reactor Ports are used, as these blocks replace Reactor Frames:
* 40 to 63 Reactor Frame
* At least 2 Reactor Ports (3-4 are common)
* 1 Laser Focus Matrix (optional in Mekanism v10)
* 1 Reactor Controller
* up to 22 Reactor Glass (optional)
* up to 1 Reactor Logic Adapter (optional)
=== Structure ===
The Fusion Reactor is a 5x5x5 spherical multiblock structure. It is primarily built out of Reactor Frames. The five central blocks on each of the four sides may be replaced by Reactor Glass or Reactor Ports. The bottom cannot include Reactor Glass, but does allow Ports. The top center block must be a Reactor Controller, and may have Reactor Glass or Ports placed next to it. Before Mekanism v10, a Laser Focus Matrix is required; it must be the center block in one of the sides.
Like with other Mekanism multiblocks, a correctly built Fusion Reactor will emit red particles when the structure is completed.
The following example structure has Reactor Glass or Ports placed wherever possible (except for the bottom), and includes a Laser Focus Matrix. This is a functional air-cooled Fusion Reactor.
== Using the Fusion Reactor ==
=== Fuels ===
The reactor runs on D-T Fuel, a mixture of Deuterium and Tritium. Deuterium is made in an Electrolytic Separator from heavy water, which is created by Electric Pumps using a Filter Upgrade. To make tritium, Lithium must be processed in a Solar Neutron Activator. 
Typically, deuterium and tritium are inserted separately into the reactor, which will automatically combine them into D-T Fuel and inject them into the reactor chamber at a customizable rate. In the Fuel tab of the Reactor Controller's GUI, players may set an injection rate which determines how fast D-T Fuel is mixed and inserted into the reactor chamber, and thus how much energy is produced. The minimum injection rate is 2. At this rate, the reactor uses 1 mB of Deuterium and 1 mB of Tritium per tick. Injection rates can only be even numbers. The highest possible injection rate is 98, at which 49 mB/t of each fuel component will be used.
Players may also pre-mix D-T Fuel in a Chemical Infuser and have it transported into the reactor. Any D-T Fuel that is inserted into the reactor directly is used up immediately, ignoring the set injection rate. This method does allow the reactor's power generation to be pushed far beyond what internal mixing of the two fuels permits, but it is not commonly attempted due to the large amount of work and materials required to enable it. Nevertheless, with sufficiently oversized fuel production it is a viable method of generating extreme amounts of power for endgame uses (or posterity). The maximum amount of D-T Fuel a Fusion Reactor can process is 1 000 mB/t.
=== Extracting Energy ===
There are three different ways in which the heat created by the Fusion Reactor can be turned into usable power: air-cooling, water-cooling, and external cooling. These methods are not exclusive, and are best used alongside each other. Indeed, they can be seen as "stages" of power extraction which build on top of each other.
The Reactor Port(s) from which energy, steam, or heat should be extracted must be switched to Output mode. To do this, the player needs to right-click it while sneaking, with a Configurator set to any "Configurate" mode in hand.
==== Air-cooling ====
The first and most simple method, air-cooling, does not require any additional setup: the reactor can turn heat directly into Forge Energy (FE) or Mekanism's own Joule, which the player may simply extract from the structure from a Reactor Port using Universal Cables, a Quantum Entangloporter, or other mods' energy transport options. (For simplicity's sake, this article will further only refer to FE as this is what most players will be familiar with.) 
With default settings, an air-cooled Fusion Reactor at its minimum injection rate of 2 will produce 400k FE/t, and up to 19.6 million FE/t at an injection rate of 98. It requires 3 Reactor Ports: one each for deuterium and tritium, and one to extract energy.
==== Water-cooling ====
The second and most commonly used method is water-cooling. Instead of only extracting FE directly, water may be piped into the structure. It will then be converted into Steam which can be used in an Industrial Turbine to create FE. This will result in significantly more power being generated in comparison to an air-cooled reactor, provided that the turbine is large enough to use all of the steam throughput. It is normally required that Saturating Condensers be included in the turbine structure so that used steam may be turned back into water and sent to the reactor, forming a closed loop (this can be skipped if the player can generate enough fresh water to keep the reactor filled).
Although most of the Fusion Reactor's heat will be used for steam production, it still produces a significant amount of FE directly, which may also be extracted in addition to steam. Therefore, a typical water-cooled reactor requires 5 Reactor Ports: two for fuel, one each for water and steam, and one for energy.
To transport steam and water, Ultimate Pressurized Tubes and Ultimate Mechanical Pipes are ideal due to their special throughput properties. These pipes form multiblock structures which act like one single tank, and their throughput is equal to the total volume of that tank per game tick. This means that the more blocks are used in an single pipe system, the higher their maximum throughput becomes. Each block adds 64 buckets per tick. As long as enough tubes/pipes are used, they will be able to handle any amount of gas/fluid, even if there are loops or dead-ends. The actual distance between input and output does not matter. Alternatively, Quantum Entangloporters may be used.
A water-cooled reactor requires a minimum injection rate of 4. Should it be set to 2, the reactor will act like a regular air-cooled reactor, and any water inside the structure will not be converted to steam.
To illustrate the large difference between air-cooling and water-cooling: an air-cooled reactor at an injection rate of 4 would produce 800k FE/t (with default settings). The steam produced by a water-cooled reactor at the same injection rate results in 1.71 million FE/t in a high-efficiency Industrial Turbine, plus an additional 200k FE/t produced directly by the reactor, for a combined 1.91 million FE/t. At the highest injection rate of 98, the turbine and reactor will produce 41.9 million FE/t and 4.9 million FE/t respectively, for a combined 46.8 million FE/t.
==== External cooling ====
Lastly, it is also possible to transfer heat directly to one or more Thermoelectric Boilers, which will use it to boil water into steam. While either Thermodynamic Conductors or Quantum Entangloporters can be used for this purpose, they will not achieve satisfactory results. Thermodynamic Conductors are lossy and, even in the best conditions, will lose a significant amount of heat. Quantum Entangloporters on the other hand do not have enough throughput to handle the the massive amounts of heat generated by a Fusion Reactor. Unlike the Fission Reactor, Fusion Reactors cannot use sodium to transport heat to a boiler.
Placing the Thermoelectric Boilers directly next to the reactor, so that five reactor ports (in output mode) on one side of the reactor will touch five Boiler Valves, is by far the best method. By itself, it is slightly more efficient than regular water-cooling, though it is best used in combination with water-cooling for best results.
Due to the space constraints imposed by the boilers, such a setup usually requires that the player plans to use boilers from the very beginning; a typical water-cooled reactor setup cannot easily be converted to one that also implements boilers and would require a full rebuilding.
=== Powering up ===
The fusion reaction is started by firing a powerful energy pulse from a Laser Amplifier into the reactor's Laser Focus Matrix. A Hohlraum filled with D-T Fuel must be inserted into the single item slot inside the Fusion Controller for the reaction to begin successfully.
The Laser Amplifier should contain at least 400 million FE, which is just enough for the reactor to instantly reach its ignition temperature of 1 million °C. Because a single Laser would take a very long time to fill the Amplifier with this much energy, it is preferable to build a chain of multiple amplifiers, each getting charged by lasers on the sides. The final Laser Amplifier, which must point into the Laser Focus Matrix, should have its Redstone mode set to "PULSE" so that it can easily be triggered with any Redstone signal. The player may wish to trigger the pulse themselves using a button, but it is also possible for the Laser Amplifier to automatically trigger when it reaches sufficient energy levels. To do this, the "Redstone Output" button in the bottom left of the Amplifier's GUI must be set to "Energy Contents". With this setting, the Amplifier will trigger a redstone pulse and thereby activate itself as soon as its internal buffer reaches the limit set by the player in the lowest of the three text fields.
A working reactor is easily identifiable by a colorful animation inside the structure (which is naturally only visible if the player chose to use Reactor Glass in the structure).
In Mekanism v10, the Reactor may alternatively be ignited using a Resistive Heater set to its maximum consumption of 10 million FE/t instead of a Laser pulse. The Hohlraum with D-T Fuel is still required. However, the Laser Focus Matrix may be omitted from the structure if this method is used. Instead, an additional Reactor Port into which heat can be inserted must be built into the structure. The reactor will automatically start the reaction as soon as the required temperature is met.
This is not commonly done, as it is very inefficient and requires far more total energy than a Laser pulse. Additionally, it requires the player to have built powerful energy generation and/or accumulated a large energy buffer before the Fusion Reactor is activated. This can easily be achieved with a sufficiently large Fission Reactor setup and a small Induction Matrix. However, many players wish to avoid this, as running a Fission Reactor can be dangerous and results in radioactive waste, while a Fusion Reactor is clean, safe, and produces significantly more energy. As a result, players will often use the Fission Reactor only as an intermediate step on their quest to achieve fusion, as nuclear waste from the Fission Reactor is required to create polonium, a major crafting component of the Fusion Reactor.
== User Interface ==
 File:Mek-fusion-gui default.png|The default page of the Controller. A Hohlraum filled with D-T Fuel is inserted.The information tabs on the bottom left side can be hovered to display the reactor's current temperature and power output in a tooltip.
 File:Mek-fusion-gui heat.png|The Heat tab. The two bars on the left side display Plasma and Hull temperatures, respectively. The top-right bar displays the reactor's internal energy storage, while the two bottom-right bars display the contents of the internal water and steam tanks.
 File:Mek-fusion-gui fuel.png|The Fuel tab. The left tank contains Deuterium, the right one Tritium. The middle tank is for D-T Fuel. The reactor's injection rate can be set using the text field.
 File:Mek-fusion-gui stats.png|The Stats tab. Displays information about the reactor's theoretical performance. These are projected values calculated from the current injection rate.
== Additional Information ==
* The Reactor Logic Adapter may be used to control the reactor with computers, such as from OpenComputers or ComputerCraft.
* Since Mekanism v10, players in Creative Mode may right-click the Laser Focus Matrix with a Configurator to instantly start the reactor, with no prerequisites beyond the D-T filled Hohlraum.
* By directly inserting 1 000 mB/t of D-T fuel into a water-cooled reactor, it produces enough steam to require using six maximum-size Industrial Turbines running at 46.67 million FE/t each, and generates a further 101 million FE/t directly, resulting in a combined 381 million FE/t.
* By combining water-cooling and the aforementioned boiler method, and directly inserting 1 000 mB/t of D-T fuel, one reactor can produce well over 500 million FE/t.