Methods and systems for lattice-based divertors

Abstract

The present disclosure provides methods and divertors for plasma reactors. The divertors may comprise internal lattice structures to facilitate conductive and convective heat transfer and provide structural support to plasma facing surfaces of the divertor.

Description

METHODS AND SYSTEMS FOR LATTICE-BASED DIVERTORSBACKGROUND

[0001] A stellarator is a plasma device that relies primarily on external magnets to confine a plasma. Scientists researching magnetic confinement fusion aim to use stellarator devices as a vessel for nuclear fusion reactions.SUMMARY

[0002] Fusion reactors may include divertors to divert a portion of a plasma in the fusion reactor. A surface of the divertor may contact a portion of the plasma. The divertor must meet structural and thermal requirements to withstand the forces and thermal flux of contact and near proximity to a plasma stream.

[0003] Disclosed herein are methods and systems for divertors that meet structural, thermal transfer, and design criteria for divertors in fusion reactors.

[0004] In one aspect, the present disclosure provides a method of removing one or more particles from a plasma comprising: (a) providing a divertor unit to a location adjacent to said plasma, wherein said divertor unit comprises an internal lattice structure; and (b) using said divertor unit, diverting an amount of said one or more particles from said plasma from said plasma. In some cases, the method further comprises flowing a heat transfer fluid through said internal lattice structure. In some cases, the heat transfer fluid transfers heat from a surface of the away from the divertor. In some cases, the said lattice structure transfers heat conduction through a solid material of said lattice. In some cases, the lattice structure transfers heat to said heat transfer fluid through convection. In some cases, the heat transfer fluid is helium. In some cases, the internal lattice structure structurally supports said divertor unit. In some cases, the internal lattice structure is fluidically sealed from said plasma. In some cases, the divertor unit is a backside divertor. In some cases, a first region of said internal lattice structure has a higher volume fraction of heat transfer fluid and a higher flux of heat from a plasma facing surface of said divertor unit.

[0005] In another aspect, the present disclosure provides a divertor of a plasma reactor comprising: a plasma facing surface, and an internal lattice structure, wherein said internal lattice structure is thermally coupled to said plasma facing surface. In an embodiment, the plasma facing surface may be decoupled from the lattice structure by a plenum (open volume / gap between the surface and the lattice) in which the coolant exits one volume of the lattice, contacts the inside of the plasma facing surface before reversing direction into the other volume of the lattice. In some cases, the internal lattice structure comprises a plurality of voids. In some cases,the divertor further comprises a heat transfer fluid. In some cases, the plurality of voids are configured to direct said heat transfer fluid through said internal lattice structure. Tn some cases, the internal lattice structure comprises copper or a copper alloy. In some cases, the internal lattice structure comprises a ceramic, stainless steel, or a combination thereof. In some cases, the heat transfer fluid is helium. In some cases, the internal lattice structure is fluidically sealed off from a plasma chamber of said plasma reactor. In some cases, the divertor further comprises a tungsten coating on said plasma facing surface. In some cases, at least about 15 % of a volume of an internal region of said divertor comprising said internal lattice structure is said heat transfer fluid. In some cases, the plasma reactor is a stellarator.

[0006] Another aspect of the present disclosure provides a system comprising one or more computer processors and computer memory coupled thereto. The computer memory comprises machine executable code that, upon execution by the one or more computer processors, implements any of the methods above or elsewhere herein.

[0007] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure.Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.INCORPORATION BY REFERENCE

[0008] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and / or take precedence over any such contradictory material.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also “Figure"’ and “FIG. herein), of which:

[0010] FIG. 1 shows a flowchart of a method for removing one or more particles from a plasma, according to some embodiments.

[0011] FIG. 2 shows a plasma flow being directed towards a backside surface of a divertor, according to some embodiments.

[0012] FIG. 3 shows a computer system that is programmed or otherwise configured to implement methods provided herein.

[0013] FIG. 4 shows an example model of a heat transfer fluid circulating through an internal lattice structure of a divertor, according to some embodiments described herein.

[0014] FIG. 5 shows an example model of heat transfer fluid paths through a lattice structure of a divertor, according to some embodiments described herein.DETAILED DESCRIPTION

[0015] While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed.

[0016] Whenever the term ‘"at least,’" "‘greater than,” or “greater than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “at least,” “greater than” or “greater than or equal to” applies to each of the numerical values in that series of numerical values. For example, greater than or equal to 1, 2, or 3 is equivalent to greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3.

[0017] Whenever the term “no more than.” “less than,” or “less than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “no more than,” “less than,” or “less than or equal to” applies to each of the numerical values in that series of numerical values. For example, less than or equal to 3, 2, or 1 is equivalent to less than or equal to 3, less than or equal to 2, or less than or equal to 1.

[0018] Certain inventive embodiments herein contemplate numerical ranges. When ranges are present, the ranges include the range endpoints. Additionally, every sub range and value within the range is present as if explicitly written out. The term “about” or “approximately” may mean within an acceptable error range for the particular value, which will depend in part on how the value is measured or determined, e.g., the limitations of the measurement system. For example, “about” may mean within 1 or more than 1 standard deviation, per the practice in the art. Alternatively, “about” may mean a range of up to 20%, up to 10%, up to 5%, or up to 1% of agiven value. Where particular values are described in the application and claims, unless otherwise stated the term “about’’ meaning within an acceptable error range for the particular value may be assumed.Fusion Systems

[0019] Fusion systems of the present disclosure may be configured to generate power (e.g., electricity) through the extraction of heat from a fusion reaction occurring within the fusion system. The fusion system can be configured to promote a fusion reaction between atomic nuclei (e.g., hydrogen, deuterium, tritium, etc.), and the energy resultant from the fusion reaction can be extracted. Examples of fusions systems include, but are not limited to, stellarators, tokamaks, or the like. Tokamaks may comprise symmetrical fusion designs, while stellarators can comprise toroidal and / or poloidal variation. Fusions systems may comprise hybrid fusion systems (e.g., fusions systems integrated with one or more additional power systems). For example, the fusion system can be integrated with one or more fission systems. An example of a hybrid fusions system may be a stellarator-mirror hybrid where neutrons generated by a plasma can induce nuclear fission.

[0020] A fusion system can comprise one or more fusion regions, one or more magnetic field generating elements, one or more power sources, one or more power extraction elements, or the like. Fusions systems can comprise a fusion region configured to confine a plasma in which a fusion reaction is occurring. The fusion region may be within a fusion chamber (e.g., a chamber sized to contain the plasma). The fusion chamber may be at a pressure of less than 1 bar (e.g., reduced pressure from ambient). For example, the fusion chamber may be under high vacuum (e,g., a pressure of at most about 0.001, 0.0005, 0.0001, 0.00005, 0.00001, 0.000005. 0.000001, 0.0000005. 0.0000001, or less Pascal) or ultra-high vacuum (e.g.. a pressure of at most about 0.0000001, 0.00000005, 0.00000001, 0.000000005, 0.000000001, or less Pascal). The fusion chamber may be configured to withstand heat generated by the plasma, high energy particles generated by the plasma, magnetic fields generated to contain the plasma, or the like, or any combination thereof. The fusion chamber may comprise materials such as, for example, steels (e.g., austenitic steels, martensitic steels, etc.), zirconium, molybdenum, tungsten, vanadium, alloys thereof, ceramics graphite, or the like, or any combination thereof. A plasma in the fusion chamber may be at a temperature of at least about 15,000,000, 20,000,000, 25,000,000, 50,000.000, 75,000,000 100.000,000, 125,000,000, 150,000,000, 175,000,000, 200,000,000, or more degrees Celsius. The plasma in the fusion chamber may have a temperature of at most about 200,000,000, 175,000,000, 150,000,000, 125,000,000, 100,000,000, 75,000,000,50.000.000, 25,000,000, 15,000.000, or less degrees Celsius. The plasma in the fusion chamber may have a temperature in a range as defined by any two of the proceeding values.Magnetic Field Elements

[0021] The one or more magnetic field generating elements may be configured to individually or collectively generate a magnetic field. The magnetic field may be configured to contain a plasma in a fusion region. For example, the one or more magnetic field generating elements can form a series of magnetic fields configured to collectively generate the containing field for the plasma. The one or more magnetic field generating elements may each individually be planar or non- planar. For example, a plurality of planar and a plurality of non-planar magnetic field generating elements can be used. The plurality of magnetic field generating elements may comprise at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, or more magnetic field generating elements. The one or more magnetic field generating elements may comprise at most about 100, 95, 90, 85, 80. 75. 70. 65, 60, 55, 50, 45, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or less magnetic field generating elements. The one or more magnetic field generating elements may comprise a number of magnetic field generating elements in a range defined by any two of the preceding values. The one or more magnetic field generating elements may comprise one or more magnetic coils as described elsewhere herein. For example, a plurality of high temperature superconducting coils can be used to form the magnetic field generating elements. The one or more magnetic field generating elements may comprise permanent magnets, one or more transient magnets (e.g., electromagnets, superconducting magnets, etc.), or the like, or any combination thereof.Power Systems

[0022] The one or more power sources may be configured to power the one or more magnetic field generating elements, provide initiation energy to initiate a fusion reaction in the one or more fusion regions (e.g., power one or more laser systems to provide energy to overcome an initial activation barrier for a fusion reaction, one or more gyrotrons, one or more neutral beam injectors, ion cyclotron resonance heating systems, etc.), provide power to one or more auxiliary systems (e.g., sensors (e.g., optical sensors configured to determine one or more properties of the plasma, electrostatic probes, interferometers, bolometers, magnetic sensors, etc.), computational systems, vacuum pumps, etc.), or the like, or any combination thereof. The one or more power sources may comprise one or more alternating current power sources, one or more direct current power sources, or a combination thereof. The one or more power sources may be connected tothe elements they are powering via one or more conductors (e.g., copper wires, etc.), one or more superconductors (e.g., one or more superconducting tapes or cables), or the like, or any combination thereof. For example, a power source can be connected to a vacuum pump via copper cabling while an additional power source can be connected to a magnetic coil via a superconducting connection. Each element of the fusion system may have its own power source. For example, each magnetic field generating element may be connected to a separate power source. A plurality of elements of the fusion system may be connected to a single power source. For example, a plurality of temperature and vacuum sensors can be connected to a single power source.

[0023] The fusion system may comprise one or more cooling systems. The one or more cooling systems may be configured to cool one or more other elements of the fusion system (e.g., divertors, blankets, structural supports, etc.). For example, the one or more cooling systems can cool one or more magnetic coils within the fusion system. The one or more cooling systems can provide enhanced longevity for the other portions of the fusion system. Additionally, the one or more cooling systems can be configured to cool one or more superconductors down to the critical temperature of the one or more superconductors (e.g., using liquid nitrogen, liquid helium, etc.).

[0024] The one or more power extraction elements can be configured to extract energy from the fusion system. For example, the one or more power extraction elements can extract some heat generated by a fusion reaction for use in generating electricity with the heat. The one or more heat extraction elements can comprise, for example, one or more phase change based heat extraction elements (e.g., water-steam heat extraction, phase change heat extraction, etc.). The fusion system may produce electricity by using energy (e.g., heat energy, energy from high energy particles, etc.) from a fusion reaction occurring in the fusion system to generate the electricity. The one or more power extraction elements can be used to provide heat for other processes such as, for example material processing, metallurgy, chemical manufacturing, etc. The one or more power extraction elements can be embedded in one or more other elements of the fusion system (e.g., one or more neutron blankets and / or shields, etc.) as described elsewhere herein. In this way, the one or more power extraction elements can provide cooling as well as extraction of usable power.Fusion Materials

[0025] The fusion system can utilize a variety of different fusion fuels for the fusion reaction. Examples of fusion fuels include, but are not limited to. hydrogenic species (e.g.. hydrogen, deuterium, tritium), helium, higher weight elements (e.g., lithium, beryllium, etc.), ions thereof, or the like, or any combination thereof. In an example, the fusion system can fuse two deuteriumfuel atoms into a helium atom to produce energy. In another example, the fusion system can fuse a deuterium ion and a tritium ion to form a helium ion and a beta particle. The fuels may be provided to the fusion system as gases. For example, gaseous deuterium and tritium can be flowed into a fusion region. The fuels can be provided to the fusion system as liquids. For example, liquid hydrogen can be flowed into the fusion region. A blend (e.g.. ratio) of different fuels can be utilized to optimize the fusion reaction and increase the efficiency of the system.Fusion Blankets

[0026] Surrounding the one or more fusion regions can be one or more neutron blankets. The one or more neutron blankets can be configured to reduce a neutron flux from the plasma region (e.g., to reduce outer exposure to high energy neutrons, breed neutron enriched materials (e.g.. breed tritium or other neutron enriched elements, for example, for use as fuel materials), extract energy from the neutrons generated by the plasma (e.g., for use in generating electrical energy), or the like, or any combination thereof. Using a neutron blanket to generate, for example, tritium, can provide an alternative fuel source for the plasma in the fusion reactor, increasing system efficiency and reducing reliance on external sources of tritium. The one or more neutron blankets can also protect other portions of the fusion system from neutron damage. For example, a neutron blanket disposed between the plasma and a magnetic coil can reduce neutron damage to the magnetic coil by absorbing neutron flux from the plasma. In some cases, one or more shielding materials can be disposed instead of or in combination with the one or more neutron blankets. The one or more shielding materials can absorb and / or deflect incoming neutrons to protect other components from neutron damage. Low-activation materials (e.g., materials that have a low susceptibility to conversion to radioactive species under neutron bombardment (e.g., silicon carbide, ferritic or martensitic steels, vanadium alloys, etc.)) can be used to harden the fusion system against degradation under neutron bombardment.Divertor Systems

[0027] The fusion system may comprise one or more divertors disposed adjacent to the one or more fusion regions. A divertor can be configured to divert a portion of a plasma in the fusion region out of the fusion region. For example, the divertor can be configured to divert a portion of the edge of the plasma out of the fusion region. The use of the divertor can produce a net outflow from the plasma region, which can aid in the removal of non-reactive species (e.g., fusion products that do not contribute to a further fusion reaction, impurities introduced to the fusion region in a fuels, impurities derived from the fusion chamber, etc.) from the plasma. In this way. the concentration of active fuel species can be maintained in the plasma, and the overall rate ofthe fusion reaction can be increased as compared to a fusion reaction without the non-reactive species removed.

[0028] The one or more divertors can be configured to impact plasma species onto the divertor to eject the plasma species from the plasma region. For example, a helium impurity ion can impact the divertor, deionize, and be directed out of the plasma chamber. The one or more divertors may be configured to be impacted on a front side surface of the divertor (e.g., a surface of the divertor facing the plasma), a backside surface of the divertor (e.g., a surface of the divertor facing away from the plasma), or a combination thereof. Examples of divertor materials include, but are not limited to, steel, tungsten, iron, tantalum, alloys thereof, ceramics, composite materials, or the like, or any combination thereof. The one or more divertors may enable gradual removal of a portion of the plasma, including waste products, during the operation of the fusion system. For example, the one or more divertors can enable a continuous operation of the fusion system with reduced downtime for waste product elimination.

[0029] In some examples, the present disclosure provides methods and systems for diverting and exhausting particles from a plasma. The plasma may comprise a hot core plasma (e.g., a core plasma at a temperature of about 100 million degrees Celsius or 10,000 electron-volts (eV)) and a cooler edge plasma (e.g., an edge plasma at a temperature of about 100,000 degrees Celsius or less than 10 eV). The edge plasma region may be the region where the exhaust of the particles predominantly occurs. The core plasma region may be where fusion processes predominantly occur. The plasma may be a part of a fusion power producing plasma (e.g., a stellarator, etc.). The fusion in the fusion power-producing plasma may involve the fusion of a plurality of fusile materials (e.g., deuterium and tritium) into a higher atomic-number nucleus. In the example of deuterium-tritium fusion, the fusion can produce a helium nucleus (e.g., alpha particle), a neutron, and 17.6 megaelectron volts of energy. In a fusion reaction, the fusion materials can be in a fully ionized plasma state. As such, the fusion materials can be controlled via use of magnetic fields. The use of magnetic field can cause the

[0030] ionized products of a fusion reaction (e.g., alpha particles) to be contained for extended periods of time in the core plasma, while a neutron produced by the fusion reaction can escape due to the lack of charge of the neutron. The fusion produced alpha particle can thermalize with the plasma, thus imparting a portion of the energy of the fusion event into the plasma, which can maintain the temperature of the plasma, maintain the fusion process, and provide harvestable energy.

[0031] Once thermalized, the alpha particle can reduce the fusion rate of the plasma, as fusion processes involving alpha particles can have lower reaction rates than those of a deuterium and tritium mix. This can reduce the efficiency of the power-producing plasma by diluting the concentration of the fusion reactants, for example deuterium-tritium. As such, the exhaust of the fusion products, along with exhaust of the other non-reactive contaminates (e.g., ions originating from the containment vessel of the power-producing plasma, impurities in the reactant gasses, etc.), can improve the operation of the power-producing plasma and increase the efficiency of the power- producing plasma.

[0032] A process for removing ions from the power-producing plasma may comprise neutralizing the ions, at which point they will no longer be confined in the magnetic field and can be removed from the power-producing plasma. This can be accomplished with a divertor (e.g., a member configured to neutralize the plasma, concentrate the newly neutral atoms, ensure the atoms are removed from the plasma and not re-ionized, remove heat from the power-producing plasma, etc.). By contacting the plasma with a divertor body, the constituent ions of the plasma can be neutralized and removed from the power-producing plasma. Alternatively, the divertor can facilitate a volumetric neutralization of the plasma with little or no contact between the plasma particles and the divertor plates. For example, both free electrons in the plasma and ions can be exhausted at a similar rate, resulting in substantially little change in the overall ionic balance of the plasma. In some cases, the ions and the electrons can be exhausted wi thout contacting the divertor, leaving the overall charge on the divertor neutral. In some cases, the electrons and ions can impact the divertor at a similar rate, resulting in a time averaged neutral divertor.

[0033] The benefits of removing ions from the power-producing plasma by having the edge plasma interact with a divertor body may include, but are not limited to reduced concentrations of impurities, a higher fusion energy output, the ability to maintain the plasma density at a predetermined value (e.g., a value optimized for energy production), the ability to concentrate the heat flowing out of the plasma onto components configured for heat removal (e.g.. components engineered to withstand the heat that is exiting the plasma, components configured to transfer the heat to a heat-based electrical generator), the spreading of the heat flowing out of the plasma over larger areas so as to not thermally overload the components of the power production system, the ability to prevent impurities introduced from outside of the plasma from entering the core plasma, or the like, or any combination thereof.

[0034] In some cases, a mean time between replacement of the components of the powerproducing plasma reactor can be increased by at least about a factor of at least about 1.1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or more with the use of a backside contact divertor.

[0035] FIG. 1 shows a flowchart of a method 100 for removing one or more particles from a plasma (e.g., a magnetically confined plasma), according to some embodiments. In an operation 110, the method 100 can comprise directing a flow of edge plasma to a backside surface of a divertor.

[0036] The backside surface of the divertor may be a portion of a stellarator. For example, the backside divertor can be a portion of a fusion stellarator.

[0037] In an operation 120, the method 100 can comprise using the divertor to divert an amount of the one or more particles from the plasma to one or more pump channels.

[0038] The one or more particles may be charged particles. The charged particles may become neutral, for example, by interaction with the divertor surface (e.g., surface recombination). The charged particles may become neutral, for example, by interactions between electrons and ions away from a surface of the divertor (e.g., a volumetric recombination). The one or more particles may be neutral particles. The neutral particles may become charged particles, for example, by interactions betw een electrons and the neutral particles (e.g., electron-impact ionization). For example, electrons can impact the housing and generate charged particles ejected from the wall of the housing. The neutral particles may become charged particles, for example, by interaction between the neutral atoms and photons (e.g., photoionization). Examples of charged particles include, but are not limited to, alpha particles, other fusion products, hydrogen ions, particles originated from the walls of the power-producing plasma apparatus (e.g., tungsten particles, iron particles, water particles, oxygen particles, etc.), impurities from a material of the plasma stream, or the like, or any combination thereof. The neutral particles may have an increased likelihood, rate, or efficiency of being exhausted by the pumping system in a system comprising a backside divertor as compared to a system comprising a front side divertor of at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, or more percent.

[0039] The backside surface of the divertor can be oriented away from a central plasma region. For example, the central plasma region can be positioned above a divertor, and an edge region of the plasma stream can contact the backside of the divertor. The edge region may be streaming through one or more channels to the backside of the divertor. The plasmastream may be directed through at least about 1.2, 3. 4. 5, 6. 7, 8, 9. 10. or more channels to reach the backsi de of the divertor.

[0040] The backside divertor described herein may enable a fusion power-producing plasma to operate at one or more improved parameters. For example, a stellarator comprising a backside divertor may operate with a lower level of impurities, which may enable lower losses and a higher fusion power output than a stellarator that does not comprise a backside divertor. The backside divertor may be more effective than other exhaust systems at removing impurities or fusion waste from a plasma, which can also improve fusion power output. Alternatively, or in addition, a backside divertor as described herein may be more effective at removing impurities or fusion waste from one or more surfaces of the reactor before those impurities or waste particles enter the plasma region of the power-producing plasma, which may increase fusion power output and enable the possibility of using a w ider range of materials for the construction of in-vessel components (e.g., components used to contain the power-producing plasma).

[0041] In particular, a backside divertor may improve the efficiency of a power-producing plasma by causing the neutralization of waste particles (e.g., alpha particles) on a surface that directs those waste particles away from a plasma region of the power-producing plasma. The structural separation between the incident site of the neutralization of the waste particles and the fusion region of the plasma stream may improve waste removal efficiency and thereby the efficiency of the plasma region and plasma reactor.

[0042] In some cases, the one or more particles may be removed from the one or more pump channels using one or more pumps. Examples of pumps include, but are not limited to. diffusion pumps, turbomolecular pumps, ion pumps, cryopumps, getter pumps, or the like, or any combination thereof. The one or more pumps can remove the one or more particles from a plasma chamber, thereby improving the purity of the atmosphere of the chamber. The backside surface of the divertor may be oriented facing the one or more pumps. The orienting the backside surface of the divertor towards the one or more pumps can reduce a rate of reabsorption of the neutralized particles into the plasma core. For example, after being neutralized on the backside surface of the divertor, a helium atom can be directed away from the plasma from the contacting and ricochet off of the backside of the divertor. In this example, the helium atom can be directed away from the plasma by merit of the angle of impact on the backside of the divertor and the fact that the main part of the plasma is on the other side of the divertor.

[0043] Particles that are diverted out of the edge flow may be more efficiently removed from the plasma reactor through use of a backside divertor. Particles that do re-enter the plasma and are re-ionized can be redirected back towards the backside surface of the divertor instead of back into the main body of the plasma. This can, in turn, reduce a reintroduction rate of impurities into the plasma, improving the performance of the plasma system. Neutral particles can be reintroduced into the edge plasma flow and may be re-ionized one or more times, thereby cooling the plasma (e.g., due to the energy used to ionize the neutral particle). The cooler edge plasma flow can result in lower impurity concentrations in the core plasma, as a cooler edge plasma may produce fewer impurities when contacting the divertor and other plasma facing components.

[0044] The divertor can be located on the side of a magnetic island within a boundary of the plasma stream. The magnetic island may be generated to provide a region of lower speed plasma movement, which can increase the amount of interaction of the plasma with the backside surface of the divertor. The magnetic field configured to contain the plasma stream may have one or more x-points. The x- points may be configured to direct ions from the plasma stream to the divertor. X-points of a magnetic field used to contain the plasma stream may be helical in nature. In some cases, the x- points have a poloidal magnetic field component, a toroidal magnetic field component, or the like, or any combination thereof.

[0045] The divertor components may be placed inside a magnetic-island chain or in a stochastic region of the magnetic field of the power-generating plasma. The divertor components can cool off in the backside region of the divertor. The divertor components may be configured such that the primary interaction region between the plasma and the divertor is the backside region of the divertor. For example, the divertor components can have any shape such that the primaiy interaction region is the backside of the divertor. The divertor components may be configured to permit the outflowing plasma from the edge plasma to stream towards the backside of the divertor. The divertor may comprise narrow slits configured to isolate the plasma flow along the magnetic field lines on a backside of the divertor.

[0046] The divertor may be configured as described elsewhere herein. For example, the divertor can be configured to be impacted with ions on a backside of the divertor, thereby neutralizing the ions and removing them from the plasma stream. The divertor can comprise slits configured to permit movement of ions from the plasma to the backside of the divertor, isolate magnetic field lines on the backside of the divertor, or the like, or any combination thereof. The divertor and / or the stellarator coil housing can comprise materials such as, butnot limited to. tungsten, steel, iron, tantalum, lithium metallic alloys, ceramics, composite materials, or the like, or any combination thereof. In some cases, the divertor is electronically grounded. In some cases, the divertor is biased to one or more voltages. In some cases, the divertor is insulated (e.g., electronically floating).

[0047] The use of the backside of the divertor for impacting particles can introduce new materials into the design space for stellarator coil housings. For example, the stellarator housing may not have to be as resilient to the effects of the plasma due to the more efficient exhausting of impurities from the plasma through use of the backside divertor. In this example, a material that produces additional impurities can be used as the material for the stellarator coil housing since the additional impurities can be more effectively removed. In this way, the use of a backside divertor can open up the design space of stellarator coil housings. Similarly, the use of a backside divertor can permit use of new materials for the construction of the divertor components, plasma-facing components, or the like, or any combination thereof. The new materials may be used due to the generation of a cool plasma edge by use of the backside divertor.

[0048] In another aspect, the present disclosure may provide a method of exhausting alpha particles from a plasma stream in a stellarator. A content of the alpha particles within the plasma stream may be maintained below' at most about 50, 45, 40. 35. 30. 25. 20. 15. 10, 9, 8, 7, 6, 5, 4. 3, 2, 1, or less mol percent during operation of the plasma. The content of the alpha particles may be reduced through use of a backside divertor.

[0049] FIG. 2 shows a plasma flow' being directed tow ards a backside surface of a divertor, according to some embodiments. The plasma flow shown can be a two-dimensional slice of a three- dimensional field that is extending out of the plane of the image. The plasma field 201 can further extend off of the top of the image. As such, the portion of the plasma flow pattern 201 can be an edge of the plasma field. The divertor 202 can be positioned such that the plasma flow does not impact the divertor on the front face of the divertor (e.g., the portion of the divertor facing the plasma field 201). Instead, the plasma flow can be directed through channels 203, with the direction of plasma flow being along the indicated arrows. The plasma can impact the diverted at sites 204, become neutral particles 205, and be diverted towards the pumps along the pump channels 206.

[0050] In some cases, the pumping efficiency of the pumping systems in high vacuum systems can be improved by the introduction of an additional ballast gas (e.g., an additional gas added to increase the pressure the pumps are removing). For example, pumping systems can have improved capture rates (e.g., rates of capture of exhaust species), reducedreintroduction rates (e.g.. reduced rates of exhaust being reintroduced upstream of the pumping system), enhanced lifetimes, and the like, when operating under higher exhaust fluxes (e.g., pressures, amounts of exhaust material, etc.). In an example, an added flow of gas directed towards the pumps in a high vacuum system can provide enhanced gas density at the pumping system as well as direct other exhaust particles towards the pumping system. For example, the addition of a ballast gas can help trap a low-density gas in the higher density ballast gas stream, which can, in turn, improve exhaust of the low-density gas.

[0051] The ballast gas stream can be introduced into the sy stem on the backside of a divertor as described elsewhere herein. For example, the ballast gas stream can be introduced through at least about 1, 2. 3, 4. 5. 6, 7. 8, 9, 10, 20, 30, 40, 50, or more nozzles located on the backside of the divertor. The ballast gas may be introduced in a subsonic stream. The ballast gas may be introduced in a supersonic stream. Examples of ballast gasses include, but are not limited to, noble gasses (e.g., argon, helium, neon, etc.), gaseous forms of other elements (e.g.. lithium, mercury, etc.), plasma gas components (e.g.. hydrogen), or the like, or any combination thereof. The placement of the inlet(s) for the ballast gas stream may be at any point along the backside of the divertor. The ballast gas may' be configured to aid in a cooling of the plasma or the portions thereof that are exhausted from the sy stem. For example, the ballast gas can be introduced at a lower temperature than the exhaust from the plasma, and the ballast gas can be configured to cool the exhaust gases. The ballast gas may aid in preserving high wear parts of the stellarator by reducing the temperature or improving the removal of the exhaust gasses. The ballast gas may reduce a heat flux at an impact point on the backside of the divertor by at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, or more times. The ballast gas and the exhaust from the stellarator may be filtered and portions of the mixture (e.g., unreacted plasma gas) can be reused in the stellarator. For example, the ballast gas. unreacted hy drogen, helium, and other impurities can be exhausted from the stellarator, the hy drogen gas can be separated from the other gases, and the hy drogen can be recycled into the stellarator. In some cases, the filtering can comprise use of thin metal foils to permit flow of hydrogen gas while trapping other species in the filtering foils.Lattice Based Divertors

[0052] In some cases, the divertor (e.g., divertor unit) may comprise a lattice structure. The term “lattice” or “lattice structure” as used herein may refer generally to a non-homogenous composition. The lattice may comprise a first material that mechanically extends to all sides of the divertor. The lattice first material may be configured with voids. The voids may form passageways through the lattice first material.

[0053] The latice (e.g., first latice material) may be a structural solid. The first material may support the interior structure of the divertor. The first latice material may be a material with a high thermal conductivity. The latice may be thermally and / or mechanically coupled to a plasma facing surface of the divertor. The latice may transfer heat away from a surface of the divertor (e.g., the plasma facing surface). The first material of the latice may comprise copper, chromium, zirconium, niobium, steel, iron, or alloys thereof. The latice material may comprise a ceramic. The ceramic may be one or more members selected from the group comprising carbides, nitrides, and oxides such as silicon carbide, boron carbide, aluminum nitride, and aluminum oxide. The lattice material may be fiber reinforced. The fiber may be carbon or glass based.

[0054] The divertor may comprise one or more plasma facing surfaces. The divertor (e.g., divertor unit) may comprise tungsten, tantalum, or other refractory material. The divertor may comprise tungsten on a plasma facing side of a plasma facing surface. The tungsten may be a coating around an exterior surface of the divertor. The tungsten coating may be mechanically coupled to a main structure of the divertor. The main structure of the divertor may be a latice structure. At least a portion of the main structure of the divertor may comprise a latice structure. The latice structure may be thermally coupled to the tungsten coating on the plasma facing surface. The latice structure may be thermally coupled to at least a portion of one or more exterior surfaces of the divertor.

[0055] The latice structure may create a plurality of voids within the divertor (e.g., divertor unit). The plurality of voids may be fluidically connected. The plurality of voids may form a plurality of passageways. The plurality of passageways may comprise a fluid. The fluid may be a heat transfer fluid. The heat transfer fluid may comprise helium, air, water, hydrogen, or carbon dioxide. The heat transfer fluid may flow through at least a subset of the plurality of voids (e.g., passageways) on the interior of the divertor to transport heat away from a surface of the divertor.

[0056] In some cases, the plurality of voids (e.g., passageways) may be fluidically coupled to an inlet. In some cases, the plurality of voids (e.g., passageways) may be fluidically coupled to an outlet. The inlet and / or outlet may be configured to provide the heat transfer fluid (e.g., helium). A temperature of the heat transfer fluid at the inlet may be lower than a temperature of the heat transfer fluid at the outlet. The plurality of voids (e.g., passageways) may direct the heat transfer fluid from the inlet, to a location thermally coupled to an external surface of the divertor, then to the outlet. In some cases, the latice structure may be fluidically coupled to at least two inlets.The lattice structure may be fluidically coupled to at least two outlets. The inlet(s) and / or outlets may be coupled to a fluid supply (e g., heat sink).

[0057] In some examples, the cross sections of the lattice structure is characteristic of the lattice structure. The lattice may comprise a diamond matrix lattice structure. The lattice may comprise a gyroid matrix lattice. The lattice may comprise a lidinoid matrix lattice. The lattice may comprise a primitive matric lattice. In an embodiment, the lattice may comprise a body-centered cubic truss structure or a face-centered cubic truss structure. The primitive matric lattice may comprise a plurality7of voids represented by sphered with six circular openings, one opening into each adjacent void. The lattice may comprise a split-p matrix lattice. The lattice structure may comprise a triply periodic structure.

[0058] The lattice matrix may be selected based on the required pressure drop of a heat transfer fluid flow ing through the lattice structure, the structural support of the lattice structure, the heat flux of the lattice structure, and / or the convective heat transfer coefficient of the lattice structure. The lattice matrix may define a first set of connected voids (e.g., passageways) and a second set of connected voids (e g., passageways). The first set of voids and second set of voids may not be fluidically connected. In addition, the first and second set of voids (pathways) may be connected at strategic locations, such as the internal side of the plasma facing surface to mix coolant flows or reverse the coolant flow direction.

[0059] The lattice structure may be designed so that the volume fraction of the voids of the lattice may drive higher or lower convection flux to some regions of the lattice. For example, by enlarging the voids near a region of high temperature on the divertor surface, an increased heat flux away from that region may be enabled. An additional benefit of the lattice structure for an internal divertor structure may be a lower weight per unit of structural strength.

[0060] In some cases, the volume percentage of the voids of the internal lattice structure of the divertor is greater than or equal to about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0061] In some cases, the volume percentage of the voids of the internal lattice structure of the divertor is less than or equal to about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0062] In some cases, the volume percentage of the voids of the internal lattice structure of the divertor may be between any two values described herein. For example, the volume percentage of the voids of the internal lattice structure of the divertor may be between about 20% and about 60%.

[0063] In some cases, the volume percentage of the heat transfer fluid within the internal lattice structure of the divertor is greater than or equal to about 1 %, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or greater.

[0064] In some cases, the volume percentage of the heat transfer fluid of the internal lattice structure of the divertor is less than or equal to about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0065] In some cases, the volume percentage of the heat transfer material of the internal lattice structure of the divertor may be between any two values described herein. For example, the volume percentage of the voids of the internal lattice structure of the divertor may be between about 20% and about 60%.

[0066] In some cases, the volume percentage of the solid material of the internal lattice structure of the divertor is greater than or equal to about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or greater.

[0067] In some cases, the volume percentage of the solid material of the internal lattice structure of the divertor is less than or equal to about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%.

[0068] In some cases, the volume percentage of the solid material of the internal lattice structure of the divertor may be between any two values described herein. For example, the volume percentage of the voids of the internal lattice structure of the divertor may be between about 20% and about 60%.

[0069] The divertor (e.g., divertor unit) may comprise a plurality of lattice subunits (e.g., cassettes). The plurality of cassettes may be manufactured individually. The plurality of cassettes may be mechanically coupled to form the interior lattice structure of the divertor. Each cassette of the plurality of cassettes may have the same lattice matrix structure. In an embodiment, each cassette is a single subunit that is then mechanically connected to the adjacent lattice subunits or to a frame that connects to the subunits. Some of the plurality of cassettes may be distinct from another of the plurality of cassettes in the lattice structure.

[0070] The lattice structure may comprise a plurality of lattice subunits (e.g., cassettes). One or more cassettes of the plurality of cassettes may be encapsulated by an armor coating. The armor coating may comprise tungsten. Two or more cassettes of the plurality7of cassettes may be mechanically fabricated in a single unit. Each cassette of the plurality7of cassettes may be a single component. For example, any joints or connections between cassettes may be integrated into a single, additively manufactured unit.

[0071] The plurality of voids of the lattice structure may not have the same size. At least one void in a first location may have a smaller size (e.g., fluid flow aperture) than a second void in a second location. The size of the void (e.g., fluid flow aperture) may control the mass flow rate (e.g., fluid flux) through that void. The lattice structure may be designed to modulate the size of the voids through the lattice structure to control the flow of the heat transfer fluid based at least in part on a heat flux of the divertor. The heat flux of the divertor may be modeled or measured.

[0072] The lattice structure may be uniform through the interior cavity of the divertor. Alternatively, the lattice structure may not be uniform. For example, in a first location, the thickness of lattice (e.g., a cross section) may be different from a thickness of the lattice at a second location. The lattice thickness may be optimized based at least in part on the conductive heat flux, convection to the heat transfer fluid, and / or structural requirements of that location of the lattice structure.

[0073] The divertor comprising an internal lattice structure may experience a thermal flux through the material of the divertor. The total thermal flux may be greater than or equal to about 1 MW / m2, 2 MW / m2, 3 MW / m2, 4 MW / m2, 5 MW / m2, 6 MW / m2, 7 MW / m2, 8 MW / m2, 9 MW / m2, 10 MW / m2, or higher.

[0074] Heat from a surface of the divertor (e.g., a plasma facing surface) may flow through a tungsten coating to the lattice structure. The heat may then transfer to a heat transfer fluid. The heat transfer fluid may flow through the lattice structure. Divertors, particularly plasma facing surfaces of divertors may experience high temperatures. In order to preserve the materials of the divertor surfaces, sufficient heat flux away from these surfaces is essential. Lattice structures may enable sufficient heat flux for plasma facing surfaces. Lattice structures may also provide sufficient structural support for divertor units. Importantly, lattice structures may provide sufficient structural support of and sufficient heat flux away from divertor surfaces facing a plasma. The lattice structure may provide the benefit of providing heat flux away from a plasma facing surface of the divertor through both convection into the heat transfer fluid and through conduction down the lattice structure.

[0075] The heat transfer fluid flowing through the lattice structure may collect impurities from the lattice structure. The heat transfer fluid may cany' the impurities out of the divertor unit. The interior of the divertor may be fluidically sealed from the exterior of the divertor (e.g., the plasma region of the fusion reactor).

[0076] The lattice structure may define a manifold configured to deliver separate fluid streams to separate locations in the lattice structure adjacent to the divertor surface. In an embodiment, theintegration of a sensor through internal passages that are separate from the coolant flow pathways may be incorporated into the design as well.

[0077] The lattice structure may be additively manufactured. The lattice structure may be 3-D printed. The lattice structure may comprise a material that is printable by a 3D printer. The lattice structure may define the plurality of voids to enable removal of 3D printing materials that are not retained to operation of the divertor unit. For example, at least one void of the plurality of voids of the lattice structure may be configured to allow a sufficient fluid flow through the lattice structure to remove a material deposited within the voids during 3D printing.Exhaust Systems

[0078] In some cases, exhaust from the fusion system can be separated and fuel species contained within the exhaust (e.g., unreacted fuel) can be recycled back into the fusion system. In this way, the amount of fuel used in the system can be reduced, and the overall system efficiency can be increased. In an example, exhaust diverted from a divertor described elsewhere herein can be exhausted from the fusion reactor, the fuel species present in the exhaust (e.g.. tritium, deuterium, etc.) can be removed from the exhaust and reinjected into a plasma region of the fusion system.

[0079] In some cases, the fusion system may comprise one or more quench detection elements, one or more quench protection elements, or the like, or any combination thereof. The one or more quench detection elements can provide computation and / or sensor based detection of a quench event in a superconducting element of the fusion system. For example, a sensor can sense a change in the current drawn through a magnetic coil, which can be related to a quench event. In another example, a software model (e.g., an inverse Biot-Savart model) can reproduce a current distribution in a superconducting magnet to detect a quench event. The one or more quench protection elements can reduce or eliminate a current flowing through a quenched superconductor, thereby reducing the damage to the quenching superconductor. Examples of quench protection elements include, but are not limited to, fuses, reverse fuses, protection heaters, dump circuits, or the like, or any combination thereof.Computer systems

[0080] The present disclosure provides computer systems that are programmed to implement methods of the disclosure. FIG. 3 shows a computer system 301 that is programmed or otherwise configured to control a plasma flow' or at least a portion of a magnetic field of a stellarator. The computer system 301 can regulate various aspects of the present disclosure, such as, for example, the movement of a plasma flow and the direction of the plasma flow to a backside surface of a divertor. In some cases, the computer system 301 can control themagnetic field itself, thereby impacting the plasma flow and its interaction with the divertor. The computer system 301 can be an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

[0081] The computer sy stem 301 includes a central processing unit (CPU, also "processor" and "computer processor" herein) 305, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 301 also includes memory or memory location 310 (e.g., random- access memory’, read-only memory, flash memory), electronic storage unit 315 (e.g., hard disk), communication interface 320 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 325, such as cache, other memory, data storage and / or electronic display adapters. The memory 310, storage unit 315, interface 320 and peripheral devices 325 are in communication with the CPU 305 through a communication bus (solid lines), such as a motherboard. The storage unit 315 can be a data storage unit (or data repository) for storing data. The computer system 301 can be operatively coupled to a computer network ("network") 330 with the aid of the communication interface 320. The network 330 can be the Internet, an internet and / or extranet, or an intranet and / or extranet that is in communication with the Internet. The network 330 in some cases is a telecommunication and / or data network. The network 330 can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network 330, in some cases with the aid of the computer system 301, can implement a peer-to-peer network, which may enable devices coupled to the computer system 301 to behave as a client or a server.

[0082] The CPU 305 can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 310. The instructions can be directed to the CPU 305, which can subsequently program or otherwise configure the CPU 305 to implement methods of the present disclosure. Examples of operations performed by the CPU 305 can include fetch, decode, execute, and writeback.

[0083] The CPU 305 can be part of a circuit, such as an integrated circuit. One or more other components of the system 301 can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

[0084] The storage unit 315 can store files, such as drivers, libraries and saved programs. The storage unit 315 can store user data, e.g., user preferences and user programs. The computer system 301 in some cases can include one or more additional data storage unitsthat are external to the computer system 301, such as located on a remote server that is in communication with the computer system 301 through an intranet or the Internet

[0085] The computer system 301 can communicate w ith one or more remote computer systems through the network 330. For instance, the computer system 301 can communicate with a remote computer system of a user. Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC's (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry ® ), or personal digital assistants. The user can access the computer system 301 via the network 330.

[0086] Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 301, such as, for example, on the memory 310 or electronic storage unit 315. The machine executable or machine readable code can be provided in the form of software. During use. the code can be executed by the processor 305. In some cases, the code can be retrieved from the storage unit 315 and stored on the memory 310 for ready access by the processor 305. In some situations, the electronic storage unit 315 can be precluded, and machineexecutable instructions are stored on memory 310.

[0087] The code can be pre-compiled and configured for use with a machine having a processer adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a pre-compiled or as- compiled fashion.

[0088] Aspects of the systems and methods provided herein, such as the computer system 301, can be embodied in programming. Various aspects of the technology may be thought of as "products" or "articles of manufacture" ty pically in the form of machine (or processor) executable code and / or associated data that is carried on or embodied in a type of machine readable medium. Machine- executable code can be stored on an electronic storage unit, such as memory (e.g.. read-only memory, random-access memory, flash memory) or a hard disk. "Storage" type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transi lory storage at any time for the softw are programming. All or portions of the softw are may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into thecomputer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that cany such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible "storage" media, terms such as computer or machine "readable medium" refer to any medium that participates in providing instructions to a processor for execution.

[0089] Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier- wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD- ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may read programming code and / or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[0090] The computer system 301 can include or be in communication with an electronic display 335 that comprises a user interface (UI) 340 for providing, for example, monitoring and controlling a plasma field. Examples of UI's include, w ithout limitation, a graphical user interface (GUI) and w eb-based user interface.

[0091] Methods and systems of the present disclosure can be implemented by way of one or more algorithms. An algorithm can be implemented by way of software upon execution bythe central processing unit 305. The algorithm can. for example, control the influx and outflux of plasma reagents, as well as monitor the composition of the plasma.

[0092] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations, or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A method of removing one or more particles from a plasma comprising:(a) providing a divertor unit to a location adjacent to said plasma, wherein said divertor unit comprises an internal lattice structure; and(b) using said divertor unit, diverting an amount of said one or more particles from said plasma from said plasma.

2. The method of claim 1, further comprising flowing a heat transfer fluid through said internal lattice structure.

3. The method of claim 2, wherein said heat transfer fluid transfers heat from a surface of the away from the divertor.

4. The method of claim 2, wherein said lattice structure transfers heat conduction through a solid material of said lattice.

5. The method of claim 2, wherein said lattice structure transfers heat to said heat transfer fluid through convection.

6. The method of claim 2, wherein said heat transfer fluid is helium.

7. The method of claim 1, wherein said internal lattice structure structurally supports said divertor unit.

8. The method of claim 1, wherein said internal lattice structure is fluidically sealed from said plasma.

9. The method of claim 1, wherein said divertor unit is a backside divertor.

10. The method of claim 3, wherein a first region of said internal lattice structure has a higher volume fraction of heat transfer fluid and a higher flux of heat from a plasma facing surface of said divertor unit.

11. A divertor of a plasma reactor comprising: a plasma facing surface, and an internal lattice structure, wherein said internal lattice structure is thermally coupled to said plasma facing surface.

12. The divertor of claim 11, wherein said internal lattice structure comprises a plurality of voids.

13. The divertor of claim 11. further comprising a heat transfer fluid.

14. The divertor of claim 12. wherein said plurality of voids are configured to direct said heat transfer fluid through said internal lattice structure.

15. The divertor of claim 11, wherein said internal lattice structure comprises copper or acopper alloy and wherein the plasma reactor is a stellarator.

16. The divertor of claim 11 , wherein said internal lattice structure comprises a ceramic.

17. The divertor of claim 13, wherein said heat transfer fluid is helium.

18. The divertor of claim 11, wherein said internal lattice structure is fluidically sealed off from a plasma chamber of said plasma reactor and wherein said internal lattice structure comprises two or more cassette subunits and wherein said two or more cassette subunits are integrated into a single, additively manufactured unit.

19. The divertor of claim 11 , further comprising a tungsten coating on said plasma facing surface.

20. The divertor of claim 13, wherein at least about 15 % of a volume of an internal region of said divertor comprising said internal lattice structure is said heat transfer fluid.

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